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INDUSTRIAL CHEMISTRY
BEING A SERIES OF VOLUMES GIVING A
COMPREHENSIVE SURVEY OF
THE CHEMICAL INDUSTRIES
EDITED BY SAMUEL RIDEAL, D.Sc. LOND., F.I.C.
FELLOW OF UNIVERSITY COLLEGE, LONDON
ASSISTED BY
JAMES A. AUDLEY, B.Sc., F.I.C. ARTHUR E. PRATT, B.Sc.
W. BACON, B.Sc., F.I.C., F.C.S. Assoc. R.M.S.
E. DE BARRY BARNETT, B.Sc., A.I.C. ERIC K. RIDEAL, M.A., PH.D.,
M. BARROWCLIFF, F.I.C. F.I.C.
H. GARNER BENNETT, M.Sc. W. H. SIMMONS, B.Sc., F.I.C.
F. H. CARR, F.I.C. - R. W. SINDALL, F.C.S.
S. HOARE COLLINS, M.Sc., F.I.C. HUGH S. TAYLOR, D.Sc.
H. C. GREENWOOD, O.B.E., D.Sc., F.I.C. A. DE WAELE, B.Sc., A.I.C.
JAMES KEWLEY, M.A., F.I.C., F.C.S. C. M. WHITTAKER, B.Sc.
J. R. PARTINGTON, M.A., PH.D. &c., &c.
THE PETROLEUM AND
ALLIED INDUSTRIES
PETROLEUM, NATURAL GAS, NATURAL WAXES,
ASPHALTS AND ALLIED SUBSTANCES,
AND SHALE OILS
BY
JAMES KEWLEY, M.A. (Cantab.), F.I.C., F.C.S.
NEW YORK
D. VAN NOSTRAND COMPANY
EIGHT WARREN STREET
1922
PRINTED IN GREAT BRITAIN
PREFACE
THE important part played by many petroleum products,
notably motor spirits and liquid fuels, during the great war,
the phenomenal growth of motor transport, and the develop-
ment of aviation have directed the attention of a large
section of the community to the petroleum industry. The
development of the oilfields of the British Empire and the
question of home supplies of liquid fuel have become matters
of national importance. The possibilities of augmenting
petroleum supplies or of partially replacing them by means
of oils derived from the distillation of oil shales and even
of coals, are receiving serious attention.
This great industry employs a multitude of men a large
porportion of whom are necessarily engaged in non- technical
work. Among these men there exists a very commendable
desire to know something of the great industry with which
they are associated, a desire which is shared by many
others whose connection with the industry is indirect.
This book has been written in the hope that it will appeal
to such, and to many university graduates to whom a
knowledge of the outlines of an industry may be of
assistance in determining their choice of a career.
An effort has been made to make the book up to date
as far as possible, and to include not only crude petroleum
and its products but also some account of the closely related
subjects, such as natural gas, the naturally occurring bitu-
minous substances, the pyrobitumens and oil shales. The
author wishes to express his thanks to Dr. H. G. Colman,
Mr. J. E. Hackford and Dr. S. Rideal for valuable
suggestions and advice ; also to acknowledge his indebted-
vi PREFACE
ness to the many excellent bulletins published by the
United States Bureau of Mines and other departments, to
the standard works to which reference is made in the
text, and finally to the Oil Well Supply Co., the Power
Specialty Co., Messrs. Watts, Fincham & Co., the Sharpies
Centrifugal Co., and the Lucey Manufacturing Corporation
for their kind assistance in the preparation of diagrams.
J. K.
LONDON,
June, 1922.
CONTENTS
PAGE
PREFACE v
PART I.— INTRODUCTORY
SECTION A. — TERMINOLOGY,
Glossary of petroleum products . . . - • . . . I
SECTION B.— HISTORY.
Early history, origin of shale-oil industry, origin of petroleum refining
industry, development of coal-coking industry, scope of petroleum
industry and its possibilities . . . 6
SECTION C. — CHEMISTRY.
Difficulties of petroleum chemistry, physical methods of separating
hydrocarbons, chemical methods of separation, hydrocarbons of various
classes and their products, sulphur, nitrogen, oxygen, helium . . 14
SECTION D. — GEOLOGY.
Geological distribution, modes of occurrence, conditions of accumulation,
types of oil-bearing structure . . .. . . . • 3*
SECTION E. — THEORIES OF ORIGIN.
Inorganic theory, theories as to animal and vegetable origin, possible
relation of petroleum to coal ........ 38
PART II.— NATURAL GAS
SECTION A.— OCCURRENCE, DISTRIBUTION, AND COMPOSITION.
Incredible waste of gas, production, occurrence underground, capacity
of gas wells, composition ........ 43
SECTION B. — APPLICATIONS.
Use for heating, manufacture of carbon black, extraction of gasoline by
compression and absorption processes, helium ..... 49
vii
viii CONTENTS
PART III.— CRUDE PETROLEUM
PAGE
SECTION A. — OCCURRENCE, DISTRIBUTION, AND CHARACTER.
General considerations, chief types of crude oils, the chief oilfields of
the world and the character of their oils, output of crude oil . . 60
SECTION B. — DRILLING AND MINING OPERATIONS.
Core drill methods, percussion methods, derricks, drilling tools,
spudding, drilling, casing, shutting off water, rotary methods, fishing
operations, flowing wells, methods of raising oil, pumping, airlift,
baling, swabbing, fires, and oilfield waste ..... 69
SECTION C.— STORAGE AND TRANSPORT OF CRUDE OIL AND ITS LIQUID
PRODUCTS.
Tanks, storage losses, pipelines, tank steamers ..... 85
SECTION D. — THE DEHYDRATION OF CRUDE OILS ON THE FIELDS.
Centrifugal methods, electric methods, distillation methods . . 93
PART IV.— CRUDE OILS PRODUCED BY THE
DISTILLATION OF SHALES, COALS, LIGNITES,
AND THE LIKE
SECTION A.— CHARACTERS AND DISTRIBUTION OF OIL SHALE.
Oil shales contrasted with oil sands, kerogen, ultimate analyses, origin
of oil shales, yield of oil, geographical distribution . . 97
SECTION B. — MINING OF SHALES .106
SECTION C. — LABORATORY EXAMINATION OF OIL SHALES . . 108
SECTION D. — RETORTING OF OIL SHALES.
Chemical changes consequent on retorting, effect of steaming, design
of retorts, types of retorts ... . 1 1 1
SECTION E. — CHARACTERS OF SHALE OILS.
Presence of unsaturated hydrocarbons, comparison with petroleum oils,
relation to conditions of retorting . .120
SECTION F. — VARIOUS TARS.
Characters of various tars as compared with petroleum oils, tars as
fuel oils, lignite industry in Germany, peat . . -125
PART V.— NATURAL SOLID AND SEMI-SOLID
BITUMENS AND ALLIED SUBSTANCES
SECTION A. — OCCURRENCE, CHARACTERS, AND PRODUCTION.
Asphalts proper, Bermudez, Trinidad, asphalt rock, asphaltites,
gilsonite, grahamite, glance pitch, asphaltic pyrobitumens, elaterite,
wurtzilite, albertite, impsonite ..... .13°
SECTION B.— APPLICATIONS.
Rock asphalt paving, road making with asphalts, other applications .142
CONTENTS ix
PART VI.— THE NATURAL MINERAL WAXES
PAGE
Ozokerite and ceresin, montan wax ....... 148
PART VII.— THE WORKING UP OF CRUDE OILS
SECTION A. — DISTILLATION OF CRUDE OIL.
Periodic distillation at atmospheric pressure, types of stills, condensers,
method of distillation, use of de phlegm ators, continuous distillation,
heat exchangers and preheaters, distillate preheaters, distillation under
high vacuum, distillation in tubular stills, Trumble system, efficiency
of distillation plant . , . . . . . . .153
SECTION B. — REDISTILLATION AND FRACTIONATION OF LIGHT OILS.
Steam stills, fractionating columns .188
SECTION C.— THE CHEMICAL TREATMENT OF PETROLEUM AND SHALE
OILS.
Treatment with sulphuric acid, types of agitators, desulphurizing
methods, action of decolorizing powders, the Edeleanu process . .197
SECTION D. — THE MANUFACTURE OF PARAFFIN WAX AND LUBRI-
CATING OIL.
Chilling of Wax distillates, types of chillers, filtration, sweating pro-
cess, refining of wax, residual and distilled lubricating oils, refining
of lubricating oils, working up of shale oils, medicinal oils, petro-
latums, greases, and cutting oils . ... . . . 208
SECTION E. — THE MANUFACTURE OF FUEL OILS, RESIDUAL OILS AND
ASPHALTS FROM CRUDE PETROLEUM.
Distilled fuel oils or gas oils, residual fuel oils, asphalts, blown
asphalts, and vulcanized asphalts ....... 224
SECTION F. — CRACKING AND HYDROGENATION PROCESSES.
History of cracking, nature of reactions, methods of cracking, processes
of Burton, Hall, Rittman, etc., hydrogenation methods, various other
methods . . . 229
SECTION G. — REFINERY WASTE PRODUCTS : THEIR REGENERATION AND
UTILIZATION.
Distillation gases, alcohols, acid sludge, naphthenic acids, regeneration
of decolorizing powders . . . . . . • 237
x CONTENTS
PART VIII.— THE CHARACTERS AND APPLICA-
TIONS OF PETROLEUM PRODUCTS
SECTION A. — BENZINES. PAGE
Special benzines for extraction purposes, etc., benzines as motor fuels,
behaviour of various types of hydrocarbons, efficiency of motor engines,
interpretation of analytical tests 241
SECTION B.— KEROSENES, ILLUMINATING OILS, ETC.
Characters of various types of kerosenes, interpretation of analytical
tests, kerosene as a source of power 252
SECTION C. — GAS OILS.
Characters and specifications of gas oils : their use as fuels for internal
combustion motors, gas oils for gas enriching ..... 257
SECTION D. — FUEL OILS.
Fuels for Diesel engine use, characters of fuel oils and tars compared,
methods of burning fuel oils, advantages over coal .... 262
SECTION E.— PARAFFIN WAX.
Various uses of wax, candles, etc 268
SECTION F. — LUBRICATING OILS.
Characters desired in lubricants, types of lubricating oils, interpretation
of tests, special lubricant and transformer oils . . . . .271
SECTION G.— ASPHALTS.
Asphalt used for road making, roofing felt, weathering of asphalt,
impregnated fabrics, mineral rubber 281
PART IX.— THE TESTING OF PETROLEUM
PRODUCTS
Need for standardization, empirical tests for boiling point range,
viscosity and colour and comparative data for various types of instru -
ments 285
SUBJECT INDEX 297
NAME INDEX 299
ABBREVIATIONS USED FOR JOURNALS REFERRED
TO IN THE TEXT
J.I.P.T.— Journal of the Institution of Petroleum Technologists.
J.S.C.I. — Journal of the Society of Chemical Industry.
J.C.S. — Journal of the Chemical Society of London.
J.R.S. A.— Journal of the Royal Society of Arts.
PETROLEUM AND ALLIED
INDUSTRIES
PART L— INTRODUCTORY
SECTION A.— TERMINOLOGY
THE terminology of petroleum is, unfortunately, somewhat
confused, as there is a good deal of ambiguity and over-
lapping in the use of names. This is due, partly to the use
of words, sometimes in a popular, sometimes in a scientific
sense, partly to the meaning of many words having been
expanded to include new ideas, and partly to the careless
extension of the use of words to include meanings which
they did not originally convey. Such misuse of words is
only too common in other industries, e.g. granite is often
used to designate such different rocks as marble and basalt.
Although there is at present no standard system of termin-
ology in use, the terms as used in this book will bear each
a definite significance. A glossary of the more important
terms is therefore appended : —
Asphalts. — Solid or semi-solid native bitumens, or solid
or semi-solid artificial products made from crude petroleum.
The asphalts are relatively easily fusible. This term
includes also those native bitumens which contain a con-
siderable proportion of mineral matter as well as those
which are nearly pure, but does not include waxes.
Asphaltenes.— Those components of bitumens which
are soluble in carbon bisulphide (benzol, or chloroform),
but insoluble in alcohol, or ether-alcohol mixture.
Asphaltites. — Native bitumens, relatively difficultly
P. ' i
2 PETROLEUM AND ALLIED INDUSTRIES
fusible, largely soluble in carbon bisulphide (gilsonite, gra-
hamite and the glance pitches). They are composed mostly
of asphaltenes and diasphaltenes.
Asphaltic Pyrobitumens. — Pyrobitumens which are
infusible, largely insoluble in carbon bisulphide, and relatively
free from oxygenated compounds.
Astatki (Ostatki). — A Russian term designating a
petroleum residual fuel oil.
Benzine. — The more volatile fractions resulting from the
distillation of petroleums, shale oils, or low-temperature
tars, up to the point at which the distillates merge into
kerosene or illuminating oils. This term includes motor
spirits, petrols, gasolines, naphthas, etc., which terms are
all synonymous except when qualified. Benzine must not
be confused with the hydrocarbon benzene C6H6.
Benzol. — The volatile or low boiling-point distillates
from high-temperature coal tars, composed largely of
aromatic hydrocarbons.
Bitumen. — A generic term covering native substances
such as crude petroleums, natural asphalts, natural waxes,
the non-mineral constituents of which are largely soluble in
carbon bisulphide.
Carbenes. — Those constituents of bitumens which are
soluble in carbon bisulphide, but insoluble in carbon tetra-
chloride.
Coal Oil. — A term sometimes used in America to include
not only oil obtained by the distillation of coal and the
illuminating oils obtained therefrom, but also illuminating
oils obtained from petroleum.
Crude Oil. — Naturally occurring liquid bitumen.
Diasphaltenes. — Those portions of bitumens which
are soluble in carbon bisulphide, and in ether, but insoluble
in ether-alcohol mixture (equal parts) .
Engine Distillate. — A product intermediate in cha-
racter between benzine and kerosene.
Gasoline. — Synonymous with motor spirits, petrol,
naphtha, or benzine. This term is in general use in
America.
TERMINOLOGY 3
Goudron. — A Russian term, meaning a petroleum residue
of high flash-point. French word for coal tar.
Kerites. — Natural solid asphaltic pyrobitumens, com-
posed for the most part of kerotenes (e.g. wurtzilite and
albertite).
Keroles. — Those portions of kerotenes which are
soluble in pyridin but insoluble in chloroform.
Kerols. — Those portions of kerotenes which are soluble
in pyridin as well as in chloroform.
Kerosene. — A mixture of hydrocarbons intermediate
in character between the lighter benzine and the heavier
gas- or solar-oil fractions. Kerosene is often miscalled
" paraffin oil " in the British Isles and " coal oil " in the
United States.
Kerotenes. — Those portions of bitumens, asphaltic
pyrobitumens or pyrobitumens which are insoluble in
carbon bisulphide.
Liquid Fuel. — A term usually confined to heavy (petro-
leum) oils of flash-point over 65° C. It is not usually taken
to include motor spirits, although this certainly might
reasonably be expected.
Malthenes. — Those constituents of bitumen (or pyro-
bitumen) which are soluble in volatile aromatic-free petroleum
spirits (sp. gr. 0-645).
Mazout. — A Tartar word synonymous with liquid fuel.
Naphtha. — A word very loosely used to include volatile
fractions derived both from petroleums and coal tars. Its
use will be avoided in this work except in connection with
coal-tar products.
Neutral Oils. — A term used in America to denote dis-
tillates from wax- or mixed-base crudes, containing paraffin
wax and lubricating oils. It is also applied to the lubri-
cating oils resulting after the removal of the wax from such
distillates by chilling and filter pressing.
Ozokerite. — A naturally occurring solid, waxy bitumen,
often known as earth wax.
Paraffin. — A hydrocarbon belonging to the methane
series.
4 PETROLEUM AND ALLIED INDUSTRIES
Paraffin Oil. — A term loosely used in the United
Kingdom to designate kerosene or illuminating oils. The use
of this word paraffin in this sense should be avoided. Also
used in America to denote lubricating oils made by dry
distillation of certain mixed-base crude petroleums. The use
of the expression will be avoided in this work.
Paraffin Wax. — The solid waxes produced by the
distillation of crude petroleums, shale or other oils.
Petrol. — Popular word for benzine or motor spirits.
Petroleum. — liquid bitumen.
Pitch. — The solid or semi-solid residue obtained from
the distillation of tars derived from the carbonization of
coal, peat, lignite, resins, woods, etc. It should not be
applied to the solid residues derived from the distillation of
bitumens.
Pyrobitumens. — Solid, infusible, naturally occurring
bodies, practically insoluble in carbon bisulphide, derived
from the metamorphosis of vegetable matter (lignites, coals,
anthracites), or of asphalts (e.g. elaterite and albertite).
Road Oil. — A trade name covering types of oils, varying
from those used for spraying roads as a dust preventive
to soft asphalts.
Stove Distillate. — A product made in California, inter-
mediate in character between kerosene and gas oil.
Tar. — A liquid derived from the distillation of coal,
lignite, peat, wood, or other vegetable substance. It is not,
in this book, applied to any bitumen product.
Wax Tailings. — A heavy distillate obtained during the
final stages of distilling certain mixed base oils down to
coke. This product contains anthracene and chrysene
produced by cracking.
Practically the first attempt to place the nomenclature
of petroleum on a scientific basis has recently been made by
J. E. Hackford, in a paper read before the Institution of
Petroleum Technologists in Februaiy, 1922.
As a result of investigations with the so-called asphalt-
ites, asphaltic and non-asphaltic pyrobitumens, their con-
ditions of occurrence and their relation to the crude oils
TERMINOLOGY 5
from which they have been derived, supported by laboratory
data and the actual experimental transformation of one
type into another, he has been able to put forward a theory,
by means of which these bodies can be correlated and thus
scientifically classified. So far, only the outlines of the
scheme have been worked out and much work remains to be
done before the conception can find general application. It
is only when such work has been amplified and recognized
that any scientific nomenclature for crude petroleums and
allied products can be evolved.
SECTION B.— HISTORY
OF the industries dealt with in this book, that of petroleum
is at the present day of outstanding importance, though
really yet only in its infancy as far as technical development
is concerned. That of shale oil, at one time more important,
is now, owing to adverse conditions, in a state of arrested
development. The growing demand for oils of all kinds, and
the possibility of the petroleum industry alone being unable
in the future to meet these requirements is, however, directing
attention anew to the potentialities of oil shale, so that under
favourable conditions, its great development in the future
may be perhaps expected.
The allied industry of the low-temperature carbonization
of coal is, at present, only in embryo. It is receiving much
attention, and the day of its commercial development is
probably not far distant.
The origin of the petroleum industry dates back to
those early ages, of the history of which we know so
little. The product of which we have the earliest records
is, as would be expected from its non-volatile nature,
asphalt.
This was used about 3000 B.C. by the Sumerians, a people
skilled in sculpture, who inhabited the Euphrates valley.
Works of art of these early peoples, now reposing in museums,
show that asphalt was used as a basis or cement for inlaying
mosaics. It seems strange that the resources of Mesopotamia,
the country in which a bitumen was first used, have not yet
been to any extent developed. The early Persians, 2500 B.C.,
used asphalt for similar purposes. The earliest known
Egyptian mummies were encased in cloth treated with a
liquid bitumen. Nebuchadnezzar constructed a high-road
6
HISTORY 7
of burnt bricks laid in asphalt, the precursor of the
modern pavement of stone blocks, grouted in with pitch or
asphalt.
It is interesting to note in this connection that the name
asphalt is derived from the Greek ao-^aXrje, signifying secure
or firm.
The Bible contains many references to crude petroleum
and asphalt. The " pitch " used in connection with the
ark was undoubtedly a bitumen. The word " slime " used
in connection with the Tower of Babel and elsewhere,
undoubtedly refers to asphalt. Many of the references to
oil, e.g. " oil out of the flinty rock," probably refer to crude
petroleum.
For more than 2500 years issues of natural gas on the
shores of the Caspian Sea have been objects of religious
reverence.
Early I,atin and Greek writers make many references,
not only to asphalts, but also to crude oils and gas. Pliny,
for example, mentions that Sicilian oil was burned in lamps
in the Temple of Jupiter. Herodotus, in 450 B.C., described
the so-called "pitch spring" of Zante, a seepage which
exists to this day.
More than 1000 years ago Yenangyaung in Burmah was
a developed oil-field. The Chinese sunk hand-dug wells
before the Christian era, ventilating the shafts with large
bellows with their usual ingenuity. They also used natural
gas as a source of heat for evaporating brine. In Japan,
too, the industry is of very long standing. The use of
petroleum in that country was first recorded in 668 A.D.,
when the people of Echigo provinces brought forward
as a present to the Emperor a marvellous burning water.
In 1613, Magara found oil at Niitsu, and actually
distilled it from a vessel, condensing the distillate, which
he sold as an illuminant. This is probably the earliest
instance of an attempt to split up crude oil into its com-
ponents.
In the days of the early North American settlers numerous
oil pits, lined with roughly hewn balks of timber, were
8 PETROLEUM AND ALLIED INDUSTRIES
often found in Pennsylvania. These were certainly of great
antiquity, probably constructed by the " Mound-builders,"
the predecessors of the present race of Indians. In 1535
asphalt was discovered in Cuba and utilized for painting
ships, and in 1595 Sir Walter Raleigh first described the
famous Trinidad Asphalt I^ake, which has since afforded
such a prolific source of supply of asphalt for paving pur-
poses. In the early part of the nineteenth century oil was
often found in wells dug for brine, in the north-eastern States
of North America, its presence being, however, regarded as a
nuisance.
During the early part of the nineteenth century attempts
were made to produce illuminating oils and lubricants by the
distillation of coals and shales. As far back as 1694 Hancock
and Portlock took out an English patent for shale tar and
pitch. In 1746 Murdoch laid the foundations of the present
coal-gas industry, and in 1846 Gessner manufactured an
illuminant from the albertite of New Brunswick, calling it
kerosene. (The older name of coal oil, however, still persists
in America to the present day.)
In 1830 von Reichenbach isolated paraffin wax from
wood tar, and gave it the name which it still bears. De la
Haye and I/aurent produced crude shale oil about the same
time, and worked it up into illuminants, lubricating oils and
wax, thus founding an industry in the south of France, which
has persisted there up to the present day. Various attempts>
which however met with little success, were made about the
same period to utilize peat.
The work of James Young forms a landmark in the
history of the distillation of shales. He first built a refinery
for the treatment of the crude petroleum which was found
in a coal-mine in Alfreton, in Derbyshire, and made lamp
oils, lubricants, and a little paraffin wax therefrom. After
a year or two, however, the flow of oil ceased, and Young
was forced to look out for other sources of supply. After
examining many samples he eventually hit upon the Boghead
coal from Torbanehill, and at once set up a retorting and
distilling plant, thus laying the foundation of the Scottish
HISTORY 9
shale-oil industry. This industry enjoyed years of prosperity
before the keen competition of the more cheaply manu-
factured petroleum products imported from America caused
it to decline. In 1858 Riebeck erected the first important
distillation plant in Saxony for the working up of lignite,
thereby establishing a similar industry, which, like that of
the Scotch shale oils, still exists.
The year 1859 marks an epoch in the history of the
petroleum and allied industries. In that year, at Titusville,
Colonel E. I/. Drake, acting for the Pennsylvania Rock Oil Co.,
drilled the first well in the United States, really bored with
the intention of finding oil. Oil was struck at a depth of
only 70 feet. This find caused great excitement, and
Oil Creek, Titusville, soon developed into an important
oil centre. The methods of distillation and refining adopted
by Young in Scotland were modified and adapted to the
requirements of the new industry, and from that time onwards
development was rapid. The new industry boomed. New
oil-fields were discovered, and developed with feverish
activity. Towns sprang up almost in a night, and rapidly
disappeared when the field became exhausted or proved a
failure.
It is lamentable to think that Colonel Drake died a poor
man. Only recently indeed have his services to the industry
been appreciated. A simple monument now stands on the
site of his first well.
The developmentof the industry in the United States iswell
illustrated by the following figures, giving the approximate
quantities of petroleum products marketed in the U.S.A. : —
Tons.
1859 300
1860 70,000
1865 357,00°
1875 1,255,000
1885 2,743,000
1895 8,233,000
1905 12,023,000
1913 3
io PETROLEUM AND ALLIED INDUSTRIES
The world's production in 1920 amounted to 97,512,000
tons (metric).
In Russia the Baku fields were worked from the early
part of the nineteenth century. About 1872 the annual
production, obtained from pit wells, had reached as high a
figure as 25,000 tons. Five years later the output was nearly
ten times as large, and in 1901 it had attained a figure of
10,850,000 tons. The Apscheron district has always been
characterized by large gushers, which have, however, become
smaller and less frequent owing to the increasing exhaustion
of the fields. The industry in Galicia dates back to 1854,
and in Roumania to 1866. The Burmah oil industry began
to develop about 1891, and that of the Dutch East Indies
about the same time. The industries in Persia, Egypt,
Mexico, Venezuela, and also in many areas in the United
States are of comparatively recent growth.
While the petroleum industry of North America was
advancing with such rapid strides, the shale-oil industry
in Scotland was fighting its way against adverse conditions,
the relatively cheap imported illuminating oils proving serious
competitors to the home-produced products. From 1850
to 1862 torbanite, a variety of cannel coal, which yielded as
much as 100 to 120 gallons of oil per ton, was worked, but as
supplies of this material became exhausted, oil shales were
substituted. These shales yielded much less oil, 20 to 50
gallons per ton, but much more ammonia. In spite of the
continually diminishing yields of crude oil given by the
shales lying at greater depths, and subsequently worked,
the industry has been able to hold its own owing to the
increased value of the principal by-products, notably the
ammonium sulphate. The progress of the industry in
Scotland has been marked by great fluctuations. At various
times, during its early days, nearly 120 concerns were
operating. In 1871 this number had decreased to 51, in 1894
to 13, and in 1906 to only 6. These latter have now been
amalgamated into one concern. In spite of the reduction
in the number of the operating companies, the output,
however, has shown a steady increase.
HISTORY ii
Tons output
Year. of Scotch Shale.
1873 .. ..
1885 .. .. 1,741,700
1895 ........ 2,236,200
1917 .. .. .. 3,116,529
1920 ........ 2,763,875
Considerable development in the coal coking industry has
taken place during the last sixty years. In the early 'fifties
of the nineteenth century Knab, Hauport, and Carves
developed recovery coke ovens. These have now largely
replaced the old coke ovens of the beehive type, all by-
products from which were invariably completely lost.
Too many of these wasteful plants are, however, still in
operation both in this country and in America. It is high
time that the squandering of our country's resources in this
disgraceful fashion was brought to an end. In 1887 Brunck
introduced benzol recovery, a process which is now generally
applied to coke-oven gases, though not to domestic coal gas.
Attention has of recent years also been paid to the re-
covery of tars from blast-furnace gases and producer plants.
The low-temperature carbonization of coal and the
economic utilization of low-grade coals are questions which
have not yet been economically solved. They are, however,
receiving much attention, and the day is undoubtedly not
far distant when the scandalous waste of these low-grade
fuels, not to mention the inefficient methods of utilization
of high-grade coals, will no longer be permitted.
Concurrently with the growth of the petroleum industry
there developed a considerable expansion in the number of
derivatives and by-products and their applications. The
comparatively recent development of the various forms of
internal combustion motor has gone hand-in-hand with the
supply of suitable fuels.
Modern printing depends largely on petroleum natural gas
for supplies of the best qualities of lamp-black ; the electrical
industries absorb large quantities of paraffin wax and
asphalts ; mineral lubricating oils are now generally used to
12 PETROLEUM AND ALLIED INDUSTRIES
the almost entire exclusion of vegetable oils, which are
incidentally more valuable for edible purposes ; and modern
roads, in order to cope with the continual increase in the
number of heavier and more rapid vehicles, depend more and
more upon natural asphalts and the similar artificial petro-
leum residues.
The recent development of the mineral separation process
which depends on the fact that certain minerals adhere to
petroleum oils affords an interesting example of a modern
application of petroleum products. The extraction of helium
in large quantities from natural gas during the last few
months of the great war, is surely one of the romances of
industrial history.
Of recent years, changes in the relative values of products
have brought about corresponding changes in the methods
of working up crude oils. The volatile fractions, which are
now of such value as fuels for internal combustion motors,
were at one time regarded as waste products and were
actually sometimes got rid of by burning. Kerosenes, in
those days, were made so as to contain as much of the volatile
fractions as the minimum legal flashpoint would allow. The
position now is completely reversed, the problem being to
include as much as possible of the kerosene light fractions in
the motor spirit. liquid fuel, at one time a drug in the
market, is now in great demand. The high aromatic content
of certain crudes, which at one time much depreciated their
value, now renders them of great importance. Such
changes are naturally only to be expected as the result of
research and development.
The petroleum industry is, however, still only partially
developed. The comparative ease with which large produc-
tions have been obtained, and the fact that the bulk of
petroleum products have been, and still are, used for fuel
purposes, are factors which do not make for efficiency.
Appalling waste has until recently been a feature of oil-
field development. Inefficient refining methods are still
largely in use. The fuel consumptions of many refineries
are still far too high, and many refining processes still in use
HISTORY 13
involve large refining losses. The industry presents, there-
fore, many interesting problems ("The Problems of the
Petroleum Industry," by W. A. Hamor, Chem. and Met.
Eng., 1920, p. 425).
The extraction of crude oil from its subterranean reser-
voirs leaves much to be desired, as it is estimated that not
much more than 30 per cent, of the underground oil is ever
brought to the surface.
The ever-increasing demand for volatile liquid fuels
suitable for high-speed internal combustion motors, caused
by the great developments in motor traction must before
long bring about a shortage of the volatile petroleum
fractions at present almost exclusively used for this purpose.
Methods of converting the relatively abundant heavier
oils into more volatile products must be worked out. Many
experimenters are indeed at work on this problem and are
attacking it mainly from two directions, viz. : " cracking "
and "hydrogenation."
So far, little work has been done in the direction of
preparing from crude petroleum, products other than the
various forms of fuels, lubricating oils, waxes, and asphalts.
Such a complex, mixture of hydrocarbons as a crude
petroleum must surely some day form the starting-point
for a large number of derivatives or by-products. The
work now being done in the direction of producing fatty
acids by the oxidation of petroleum oils probably fore-
shadows such a development. The opportunities for
research in this direction are great indeed.
GENERAL REFERENCES TO PART I., SECTION B.
Abraham, " Asphalts and Allied Substances." D. van Nostrand Co.,
New York.
Ells, " The Bituminous Shales of New Brunswick and Nova Scotia."
Canada Dept. of Mines.
Gesner, " Coal Oils." Bailliere Bros., New York. 1865.
Henry, " History and Romance of the Petroleum Industry." Bradbury,
Agnew and Co., London.
Pascoe, " Memoirs of Geological Survey of India," vol. 40.
Redwood, " Treatise on Petroleum," vol. i. C. Griffin and Co.
Ross, " Evolution of the Oil Industry." Doubleday, Page and Co.,
New York.
Scheithauer, " Shale Oils and Tars." Scott, Greenwood and Son.
SECTION 0.— CHEMISTRY
IT is at first sight surprising to find that so little is really
known of the chemistry of petroleum (and shale oil) in view
of the enormous importance which the industry has now
attained. When, however, the complexity of the subject
and the difficulties of investigation are taken into considera-
tion, the lack of knowledge, although deplorable, is readily
understood. The same may be said of the chemistry of
coal, and of its distillation products under various conditions.
This subject is of even greater importance, as the supplies
of petroleum are limited, the end of many great producing
fields being already in sight. The world's supplies of shale
and coal are undoubtedly far greater than of petroleum, and
in years to come the shale oil and coal distillation industries
must play a great part.
Crude petroleums, shale oils, and tars, are composed
mainly of hydrocarbons, associated, particularly in the case
of tars, with varying proportions of oxygen, sulphur, and
nitrogen derivatives.
Owing to the enormous number of isomeric hydrocarbons
which may exist when the molecule contains more than
5 or 6 carbon atoms, and to the similarity in the properties
of members of any one series, the isolation and investigation
of individual hydrocarbons from crude oils present very
great difficulties, as a natural consequence of which the
volatile hydrocarbons of relatively low molecular weight
have received most attention. Many of these have been
isolated in a state of purity. Several of the lower members,
particularly those of the aromatic series, have actually been
extracted commercially from petroleum. For example,
many thousands of tons of trinitrotoluene were made from
14
CHEMISTRY 15
toluene derived from a Borneo petroleum during the recent
war (Kewley, J.I.P.T., 1921, p. 209).
A further difficulty in the isolation and examination
of the constituents of higher boiling points, arises from the
fact that chemical changes often take place during the dis-
tillation of crude petroleums, even at temperatures as low
as 200° C., so that it by no means follows that components
found in distillates are present as such in the crude. This
is unfortunate, as distillation is naturally the obvious means
of effecting some sort of separation.
Such decomposition or " cracking " as it is termed, finds,
however, a technical use, being applied to the increasing of
the output of light fractions (benzines) from certain crudes
(vide Part VII., Section F).
Recently, however, Krieble and Seyer (J. Am. Chem.
Soc., 1921, p. 1337) have shown that by distilling under
really high vacuum, as low as O'i mm., heavy hydrocarbon
oils can be distilled up to temperatures as high as 300° C.
without cracking.
If the various hydrocarbons or other bodies present
could only be separated from each other by physical means,
other than distillation, much more might be learned of their
chemistry. The only physical means which at present
appear to be available are : —
(1) Distillation under high vacuum.
(2) The differential action of solvents.
(3) Diffusion.
In connection with the first it may be mentioned that
paraffin wax, which readily cracks on distillation, may be
easily distilled in high vacuum without any appreciable
change. High-vacuum distillation is technically employed
in the manufacture of the best qualities of lubricating
oil, in order to avoid decomposition as far as possible.
An example of the second method is afforded by Lessing's
process for the treatment of coal tars (Eng. Pat. 130362 of
1919). When such a tar is treated with benzine containing
no aromatic hydrocarbons, it is split up into a pitch which is
precipitated out, and a tar oil which dissolves in the spirit,
16 PETROLEUM AND ALLIED INDUSTRIES
from which it is separated by distillation. The tar and oils
so obtained are somewhat different from those obtained by
distillation. The pitch contains much less insoluble free
carbon than does that resulting from ordinary distillation
treatment, as it lacks the free carbon formed by decomposi-
tion during distillation, and the tar oils also differ somewhat
from those obtained by distillation. It is evident therefore
that considerable changes take place during the distillation
of coal tar. The application of a similar method (if a suitable
solvent were found) to crude oils would doubtless lead to
interesting results.
A further application of this method is afforded by
the Edeleanu process, in which liquid sulphur dioxide at a
low temperature is used for the removal of aromatic and
unsaturated compounds from petroleum distillates (vide Pt.
VII., Sec. C). The use of dimethyl sulphate (Valenta, Chem.
Ztg., 1906, p. 266) has been advocated for the separation of
aromatic hydrocarbons, but its use has limitations, and it is,
moreover, objectionable owing to its exceedingly poisonous
nature. Various alcohol mixtures have been used as
differentiating solvents by Charitschkoff and Wolochowitsch
(Chem. Ztg., 1902, p. 224), carbon tetrachloride by Graefe
(Chem. Rev., 1906, p. 30), acetic anhydride and alcohol ether
mixtures, by Zaloziecki. A method of estimation of paraffin
wax is based on its relative insolubility in a mixture of
alcohol and ether at low temperatures (Holde, "Untersuchung
der Mineralole und Fette," 3rd edition, p. 28).
I<ittle work has as yet been done on the lines suggested
by method (3), Day (Bulletin 365, U.S. Geol. Survey),
Gilpin and Bransky (Amer. Chem. Journal, vol. 44, p. 251),
Bngler and Albrecht (Zeit. angew. Chem., 1901, p. 889) have
examined the behaviour of crude oil when subjected to slow
nitration through finely divided media, such as fuller's-
earth. Day made the following observations : " (i) when
petroleum is allowed to rise in a tube packed with fuller's-
earth, there is a decided fractionation of the oil, the fraction
at the top of the tube being of lower specific gravity than
that at the bottom. (2) When water is added to fuller's-
CHEMISTRY 17
earth which contains petroleum, the oil which is displaced
first differs in specific gravity from that which is displaced
afterwards, when more water is added. (3) When petroleum
is allowed to rise in a tube packed with fuller's-earth, the
paraffin hydrocarbons tend to collect in the lightest fraction
at the top of the tube and the unsaturated hydrocarbons
at the bottom.
This filtration process on a natural scale is undoubtedly
responsible for the occurrence of many abnormal crude oils,
the so-called white oils which have been found in Russia,
Canada, and elsewhere, usually in small quantities. Indeed,
many crude oils have undergone such a filtration to some
extent, as the occurrence of oil in the formation in which it
was formed (its mother rock) is unusual ; migration has in
most cases taken place.
Much work still remains to be done on these lines,
especially in connection with the more complex compounds
which constitute the natural asphalts, such as gilsonite,
grahamite, elaterite, and others, the natural waxes or
ozokerites, as well as on the heavy asphaltic crudes. It is
undoubtedly by the examination of these bodies, rather than
the volatile and simpler constituents, that light will be thrown
on the relations of crude oil with each other and with coals,
and incidentally on the much-discussed question as to the
origin of petroleum.
Attempts have been made to utilize other physical
characters for the determination of the class to which a
hydrocarbon belongs. Darmois (Comptes rendus, 1920, p.
952) has examined the dispersion of several classes of hydro-
carbons. He finds that the specific dispersion, i.e. the
difference between the refractive indices for two definite
wave lengths, divided by the density, is a constant for
particular series of hydrocarbons. (In his work he used the
two spectrum lines Ha and Hy.)
In the case of hexane (n) he finds density 1/4 0-6634.
-• ^\ ftf
Aw =103 and -j =
p.
i8 PETROLEUM AND ALLIED INDUSTRIES
For six hydrocarbons of the paraffin series and for nine
/\fl7
of the cycloparaffin series he finds -j-= about 155.
For hydrocarbons with one double bond, e.g. amylene,
/\*W
he finds -^ = about 193.
For hydrocarbons with two double bonds, e.g. methyl
A 47.
hexadiene, he finds -^ = about 228.
(t
And for the aromatic hydrocarbons he finds a value about
300.
Such work may prove of great value in future
researches.
Apart from these physical methods, certain chemical
methods may also be employed for the separation of the
compounds of crude oil and for their estimation. There
are, of course, objections to such chemical methods of
analysis, as the behaviour of most of the compounds under
investigation towards many reagents is by no means well
known.
For example, unsaturated hydrocarbons are usually
removed and estimated by absorption with sulphuric acid,
aromatic hydrocarbons by absorption with oleum in the
cold, after the removal of unsaturated hydrocarbons (Bowrey,
J.I.P.T., vol. 3, p. 287). These methods are by no means
simple, however, as overlapping of the action of the acid
takes place. Xylol, and higher aromatics, for example, are
partly removed by 96 per cent, sulphuric acid, which also
causes polymerization of some of the unsaturated bodies.
Further, oleum certainly reacts with certain non-aromatic
constituents too. The isolation, therefore, of even any one
class of hydrocarbons, much more so of any individual of a
class, is a matter of difficulty. This is, however, generally
only a matter of minor importance in practice, though of
greater importance from the point of view of research.
A further possible method of investigation is suggested
by the recent work of Tausz and Peter (Zentr. Bakt. und
Parasit., 1919, vol. 49, p. 495 ; and J.5.C.7., vol. 39, p. 357A)
CHEMISTRY 19
on the preferential action of certain bacteria. They found
that paraffins can be separated from naphthenes by the
action of B. aliphaticum and B. aliphaticum liquefaciens,
bacteria which they isolated from garden mould. These
species are inert towards cyclic hydrocarbons, but attack
paraffins. In this manner Tausz and Peter have isolated
1.3 djmethylcyclohexane and 1.3.4 trimethylcyclohexane
from a petroleum. This method is as yet in its infancy,
but it certainly has possibilities.
Hydrocarbons of most of the known series have been
detected in some one or other of the many varieties of crude
petroleum. Those of the paraffin (aliphatic) and naphthene
(alicylic) series, however, predominate, those of the aromatic
series occur to a less extent and in fewer crudes, while
members of the less known series are also undoubtedly of
great importance.
There is no known crude composed exclusively of the
members of any one series, but many crudes are characterized
by the presence in predominating quantities of hydro-
carbons of one of the series.
The paraffin series of hydrocarbons (CnH2n+2) are
widely distributed, occurring to some extent in most crudes,
particularly in the lighter fractions. They enter very largely
into the composition of the crude oils of the eastern states of
North America, to the almost complete exclusion of members
of other series. They occur to a less extent in those of Galicia,
Rumania, Persia, Burmah, Mexico, Sumatra, etc., and in
smaller proportions still in those of Russia, Borneo, South
America, and California. The more volatile members of
the series, methane to pentane, occur in natural gases
and the higher members constitute the paraffin waxes.
The liquid members have lower specific gravities than do
those members of other series having similar boiling points.
B.p. Sp.gr. at 15° C.
Hexane C6H14 . . . . 70 0*662
Cyclohexane C6H12 . . . . 70 0746
Hexylene C6H12 .. . . 5§ °*685
Benzene C6H6 .. ..80 0-884
20 PETROLEUM AND ALLIED INDUSTRIES
Their specific gravities rise with the boiling points,
e.g.—
w-pentane . . . . sp.gr. 0*627/15° C. b.p. 36-3° C.
»-hexane .. .. „ 0*658/20° C. „ 68-9° C.
w-heptane . . . . „ 0-683/20° C. „ 98-4° C.
w-decane .. .. „ 0730/20° C. „ 173-0° C.
This is generally the case, but the aromatic hydrocarbons
show the reverse effect.
Owing to the fact that motor spirits from Appalachian
crudes were early in the market low specific gravity came to
be regarded as a criterion of quality, a popular fallacy which
died very hard.
In the case of a motor spirit composed entirely, or nearly
so, of paraffin hydrocarbons, low specific gravity is an
index to degree of volatility, but as a means of comparison
for motor spirit of various origins it is entirely misleading,
as may easily be seen from the fact that a heavy kerosene
of paraffin hydrocarbons, utterly unsuitable as a motor
spirit, has a specific gravity lower than that of benzol, an
excellent motor fuel.
The'paraffin hydrocarbons, though stable to most reagents,
readily undergo cracking at high temperatures. Such
cracking is easily effected in the case of paraffin wax (Mabery,
Proc. Am. Phil. Soc., 1897, p. 135). The unstability of the
paraffins is also evident from the fact that they are the
hydrocarbons which most readily show the phenomena of
detonation (knocking or pinking) when used in automobile
internal combustion engines. In this respect they show up
badly in comparison with the naphthenes and worse still
in comparison with the aromatics (Ricardo, " The Influence
of various Fuels on the performance of Internal Combustion
Engines," Automobile Engineer, February, 1921).
The higher paraffins occur as waxes also in wood tar, and
in the various oils resulting from the distillation of cannel
coals and shales, and in the oil produced by the low tem-
perature distillation of coal. They occur also in ozokerit, a
natural wax often found associated with petroleum, which
CHEMISTRY 21
contains the higher members of the series from C24H50
upwards.
It is not proposed to give here a detailed list of the various
hydrocarbons and their properties. For these, reference
should be made to Engler-Hofer, " Das Erdol," vol. i, where
tabulated analyses of numerous crude oils are also given.
The hydrocarbons of the olefine series (CnH2n) are
unsaturated open chain compounds. They are isomeric
with the members of the naphthene series (CnH2n-6H6)
which, on the contrary, are saturated ring compounds.
The defines occur in crude petroleums comparatively
rarely and in small quantities. They are, however, present
in shale oils and tars and in many petroleum distillates,
as they are among the products resulting from the cracking
of paraffins and other hydrocarbons. They are readily
absorbed by sulphuric acid, are oxidized by permanganate,
and form addition compounds with bromine. They are also
soluble in liquid sulphur dioxide, and may thus be separated
from aliphatic hydrocarbons. This reaction finds technical
application in the Edeleanu process (vide Pt. VII. , Sec. C).
They react with ozone to form ozonides. The paraffins and
naphthenes do not react in this way (Harries, Lieb. Annal.,
1906, p. 343 ; 1910, p. 374). They react with mercury salts,
and these reactions have been proposed as the basis for
methods of estimation of these hydrocarbons (Engler-
Hofer, "Das Erdol," vol. i, p. 269). Small quantities of
olefines have been found in Galician, Rumanian, Caucasian,
Canadian, and South American oils.
The members of the diolefine, acetylene, and other
unsaturated series (Tausz, Zeit. angew. Chemie, 1919, vol. 32,
p. 233) are of minor importance in petroleums, but are
normal constituents of many tars and shale oils. The
diolefines, owing to their readiness to undergo oxidation and
polymerization, are undesirable constituents in petroleum
products (other than liquid fuels) ; in a motor spirit, for ex-
ample, they give rise to the formation of gummy deposits. In
removing them, unfortunately, quantities of olefines, which in
themselves are not undesirable constituents, are removed too.
22 PETROLEUM AND ALLIED INDUSTRIES
The members of the naphthene or alicylic series, on the
contrary, play a very important part in the composition
of well-known crude oils. These differ from the olefines,
which have the same empirical composition, in that they are
saturated ring compounds. As regards their behaviour
towards reagents such as sulphuric and nitric acids, halogens,
etc., they stand between the paraffin and the aromatic
hydrocarbons. They are not attacked by sulphuric acid in
the cold. They can be oxidized by vigorous oxidizing
agents, the ring being then broken up. As the individual
members of the series, however, do not all behave in the
same manner towards any reagent, there is no general method
by which members of this series can be separated from
mixtures with paraffin hydrocarbons.
The hydrocarbons of this series are of higher specific
gravity than the corresponding paraffins, e.g. —
Cyclohexane °799 at o° C.
Hexane . . . . . . . . 0*676 at o° C.
Methylcyclohexane . . . . 0778 at o° C.
Heptane . . . . . . 0701 at o° C.
Naphthenes occur in Caucasian petroleums, of which they
constitute a large proportion ; to a considerable extent also
in the petroleums of Galicia, Rumania, Egypt, Borneo, Peru,
California, and elsewhere.
From the practical standpoint naphthenic crudes yield
good motor spirits, the naphthenes being superior to the
paraffins in this respect, as they can be used in engines of
higher compression and therefore of greater thermal effi-
ciency. They yield also kerosenes of good illuminating
quality, and good lubricating oils of low cold test.
Hydrocarbons of the aromatic series are of common
occurrence in.crude petroleum, though generally to the extent
of below 10 per cent. In a few exceptional types, however,
the percentage may be much higher. The crude oils of
East Borneo are remarkable in this respect, containing as
much as 40 per cent, of aromatics (Jones and Wooton,
J.C.S., 91, pp. 114, 1146).
CHEMISTRY 23
These hydrocarbons occur also in coal tars, especially
in those resulting from high-temperature distillations. lyow-
temperature distillation tars and shale oils are relatively
poorer in aromatics and richer in paraffins. The hydro-
carbons of this series are of relatively high specific gravity,
which in this case decreases somewhat with the increase of
molecular weight, e.g. —
Benzene 0-884 at I5° C.
Toluene 0*870 „
P. xylene . . . . . . 0*866 „
Cymene 0-863
They possess greater solvent properties than do the members
of the paraffin and naphthene series, so that good extraction
spirits can be made from crudes relatively rich in these
compounds. They are readily sulphonated by sulphuric
acid and on these properties methods of estimation have
been based. They are soluble in cold liquid sulphur dioxide
and are often extracted from kerosenes by a method based
on this behaviour (vide "Edeleanu Process/' Pt. VII.,
Sec. C). They are readily nitrated by a mixture of sulphuric
and nitric acids.
Ross and feather (Analyst, vol. 31, p. 285) in this way
isolated decahydro- and tetrahydro-naphthalenes from a
Borneo gas-oil distillate.
Several of the nitro-compounds, e.g. dinitrobenzene,
trinitrotoluene, trinitroxylene, are used as explosives. The
lower members of the series may be separated from admixture
with other hydrocarbons by taking advantage of their ready
nitration, as the mononitro compounds may easily be
separated by distillation, and subsequently converted into
the trinitro derivatives.
Aromatic hydrocarbons of the higher series CnH2n-8»
CnH2n-io> and so on have been found in small quantities
in various petroleums and have been isolated from the
distillates boiling at temperatures over 200° C. But as
chemical changes begin to take place at these temperatures,
it is by no means proved that these hydrocarbons exist as
24 PETROLEUM AND ALLIED INDUSTRIES
such in crude oils. They are found also in coal-tar distillates.
Indene, for example, was isolated from coal-tar light oils by
Kraemer and Spilker (Zeit. angew. Chem., 1890, p. 734).
Naphthalene is an important constituent of coal-tar distillates,
as are also methyl- and phenyl-naphthalenes, acenaphthene
and its derivatives, diphenyl, fluorene, anthracene, phenan-
threne and their derivatives, fluoranthene, pyrene, chrysene,
retene, and others (Malatesta, " Coal Tars and their
Derivatives," Chap. III.), but many of these have also been
found in petroleums (Engler-Hofer, " Das Erdol," vol. i).
In addition to the members of these main hydrocarbon
series, members of many other less known and little investi-
gated series have been found. The presence of many
saturated hydrocarbons of unknown constitution, hydro-
carbons of the terpene series and of other more complicated
series from CwH2w_io to CwH2w_20 nave been indicated
by many workers, such as Mabery, Coates, Markownikoff,
Engler, Marcusson, and many others. Detailed references
to these are given in Kngler-Hofer, " Das Erdol," vol. i.
Hydrocarbons of the series CnH2n, CnH2n_2 and CnH2n_4
have recently been isolated from the petroleum extracted from
the bituminous sands of Alberta (Krieble and Seyer, /. Am.
Chem. Soc., 1921, p. 1337). Our knowledge of the properties
of the hydrocarbons of these series is, however, very vague ;
indeed the field may be said to be practically unexplored.
Apart from the hydrocarbons and the higher, practically
uninvestigated, asphaltic bodies, many other compounds
occur as unimportant constituents (usually regarded as
impurities) in petroleums and as normal constituents in
tar. Sulphur compounds, and to a much less extent nitrogen
and oxygen compounds, occur even in the lighter fractions
of certain petroleums, more so in shale oils and tars ; of the
composition of the higher sulphur and oxygen compounds,
which undoubtedly play an important part in the composition
of many asphalts, very little is as yet known. Research in
this difficult field should yield interesting results.
Sulphur is found to some extent in practically all crude
oils. In some cases it is an essential constituent of the crude,
CHEMISTRY 25
e.g. in the case of the thioasphaltic oils of Mexico, in other
cases it is merely an impurity ; in some cases it is found in
solution (Peckham, Proc. Am. Phil. Soc., 1897, p. 108) in
the oil. Many crude oils of Ohio, Canada, Mexico, Persia,
Egypt, California, and Texas and elsewhere are relatively
rich in sulphur compounds.
Thiophene has been found in German crudes, thiophene
and its homologues in Canadian, Caucasian, and Persian oils ;
thioethers in Ohio oils and mercaptans in Persian oils. The
sulphur compounds occurring in petroleum have, however,
as yet received comparatively little attention (Mollwo
Perkin, J.I.P.T., vol. 3, p. 227).
The presence of sulphur in relatively large quantities
is interesting to the student of the origin of petroleum, as
such large amounts as are sometimes found could not have
originated from animal or terrestrial vegetable matter. In
certain cases sulphur in combination must have resulted from
secondary changes owing to contact of the oil during migra-
tion with either sulphur or sulphates, and such sulphates, e.g.
gypsum, are indeed often found in close association with
oils relatively rich in sulphur (Hackford/./.PT., 1922, vol. 8).
Sulphur compounds are usually present in considerable
quantities in shale oils. The difficulty of eliminating the
sulphur compounds has always been one of the obstacles
to the working up of the English shales for oil.
Nitrogen compounds occur in small quantities in many
crude petroleums, e.g. in Californian, Japanese, and Algerian.
They occur usually in the form of homologues of pyridin
(some Californian crudes are unusually rich in quinolines).
The presence of nitrogen compounds is, however, of no
practical importance as they are usually eliminated in
refining. They occur to a much larger extent in shale oils
and various tars, mainly in the form of pyridin and anilin
homologues.
Oxygen compounds are found to some extent in most
crudes, and in the case of certain asphaltic oils are un-
doubtedly an essential constituent. In certain oils, e.g. some
of California, the oxygen compounds are phenols and in others,
26 PETROLEUM AND ALLIED INDUSTRIES
e.g. Russian, naphthenic acids. Practically no work has
as yet been done on the oxygenated compounds present in
petroleums. Phenol and its homologues form important
constituents of coal tar, while other oxygenated products,
e.g. ketones and acids are found in wood tars.
Although the complete examination and identification
of the constituents of a petroleum distillate is too difficult
an undertaking ever to be of much practical value, still a
ready means of determining even approximately the per-
centages of paraffins, naphthenes and aromatics in a light
petroleum product, for use as a motor spirit, is of prime
importance, owing to the very great difference in value, as
motor fuels, of the hydrocarbons of these three groups.
Chavanne and Simon (Comptes rendus, 1919, p. 285) have
done much work in this direction by applying the aniline
solubility critical temperature method. Tizard and Marshall
(J.S.C.I., 40, p. 20T) have developed and modified this
method and find it particularly applicable to the estimation
of aromatic hydrocarbons.
The temperature at which a mixture of equal volumes
of pure freshly distilled aniline and the benzine separate out
is called the aniline point. The aniline point for paraffins
is high, about 70° C., for naphthenes it is lower, about 50° C.,
and for aromatics is much lower still.
It has been found that the difference in aniline point
for a benzine, before and after the removal of the aromatics
by sulphonation, is proportional to the original aromatic
content, provided that unsaturated hydrocarbons are absent.
Thus a lowering of aniline point of 4-2° C. corresponds to
5 per cent, by weight of aromatic hydrocarbons, of i8'i° C.
to 20 per cent., of 39*8° C. to 40 per cent., and so on. The
method has so far only been worked out for the first three
members of the aromatic series. The method is capable of
further development and its use may be considerably
extended.
The chemistry of coal is a subject which has lately
been receiving much attention, but is as yet little understood.
The subject, however, lies outside the scope of this volume.
CHEMISTRY 27
The question of the origin of petroleum and its possible,
or probable, relation to coal has also been the subject of
much discussion. Hackford (Trans. Am. Inst. of Mining
and Metallurgical Engineers, September, 1920) has converted
petroleum oils by slow oxidation or thionization aided by
gentle heat into bodies termed by him " kerotenes," most of
which are quite insoluble in any of the known solvents and
are probably identical with certain constituents of coal.
He has also shown that the portions of coal soluble in pyridine
consisted partly of asphaltenes (i.e. those portions of bitumens
which are insoluble in ether or ether-alcohol, but are soluble
in carbon bisulphide). He concludes that most of the
insoluble portion of coal consists of a true bitumen which
has been transformed into an insoluble kerotene. The
kerotenes (the portions of a bitumen which are insoluble in
carbon disulphide) experimentally produced from petroleum,
yield, on distillation, the same products as are obtained by
the distillation under the same conditions of the kerotenes
derived from coal.
Fischer and Gluud (Ber.t 1919, p. 1053) claim to have
established that light paraffins exist as such in certain coals.
Tausz (Zeit. angew. Chem., 1919, p. 361) has pointed out
that all three xylenes and ethylbenzene are found, not only
in the distillates from coal, but in some petroleums too.
A high melting-point paraffin wax was actually found in
a ^Lancashire coal-seam many years ago (Sinnatt, Colliery
Guardian, November 14, 1919).
Although the products up to the present commercially
extracted from petroleum have been in the main those
obtained by the physical methods of distillation and nitra-
tion, i.e. various motor and extraction spirits, illuminating
oils, lubricants of various grades, fuel oils, waxes, and
asphalts, there are indications that in the future products
obtained by chemical means will play an important part.
Recently alcohol has been prepared from the ethylene
present in coke-oven gases by Bury and Ollander (Chem.
Age, 1920, p. 238, and Eng. Patent 147360 of July 22, 1920).
The ethylene is absorbed by concentrated sulphuric acid
28 PETROLEUM AND ALLIED INDUSTRIES
and the ethylhydrogen sulphate so formed is subsequently
hydrolysed by steam distillation, yielding ethyl alcohol
and sulphuric acid again in the well-known manner.
C2H4+H2S04=C2H5H.S04
C2H6H.S04 -f H20 =C2H5OH +H2SO4.
In a similar way the propylene evolved from the cracking
stills used to crack gas oils into motor spirits (vide P. VII.,
Sec. F) is converted into isopropyl alcohol (Carleton-Ellis,
Petroleum Mag., January, 1921, p. 40), and this alcohol is
used in admixture with benzene as a motor fuel.
By chlorination, chlor derivatives of hydrocarbons suitable
for use as non-inflammable solvents may be obtained. By
chlorination and subsequent removal of the chlorine, drying
oils may be obtained.
Much work has recently been done on the oxidation of
the higher paraffins to fatty acids. Griin, Ulbrich, and
Wirth (Ber.t 1920, p. 987) found they were able to oxidize
paraffin wax and obtain a whole range of fatty acids there-
from. lySffl (Chem. Ztg., 1920, p. 561) oxidized petroleum
hydrocarbons with the assistance of lead or mercuric catalysts,
to fatty acids which when mixed with tallow or coconut
fatty acids yielded satisfactory acids for soap making.
Schaarschmidt and Thiele (Ber., 1920, p. 2128) chlorinated
paraffin wax, and after removal of the chlorine by alcoholic
potassium hydroxide oxidized the hydrocarbons to fatty
acids. Fischer and Schneider (Ber., 1920, p. 922) oxidized
paraffin wax by means of air under pressure to fatty acids.
These researches foreshadow a possible alternative supply of
fatty acids for soap making and the consequent liberation
of certain vegetable oils for more useful purposes.
Pentane can be converted by a rather complicated process
into isoprene, the possibility of synthetic rubber from
petroleum being thus opened up.
The investigation of possible petroleum by-products is
one of the most promising fields for research. Our ignorance
of the chemistry of petroleum as well as that of shale oils
and tars of various kinds is really relatively profound.
CHEMISTRY 29
With adequate research these industries will undoubtedly
expand and considerably extend their yield of important
products.
A distinctly new line in petroleum chemistry has been
struck by Hackford, the preliminary outline of which has
been published by him in a paper read before the Institution
of Petroleum Technologists (J.I.P.T., 1922, vol. 8). He
has endeavoured to take a very broad view of the subject
and has studied and correlated data, many of which are the
result of his own investigations, with a view to arriving at
some general conception as to the interrelation of various
types of crude oil and the relation to crude oils of the
natural gases, and natural asphaltic bodies such as asphalt-
ites, elaterites, and the like, which are often found in close
association with them. On the basis of this work he
suggests a classification for bitumens, which has the merit
of being based on their chemical compositions.
As all crudes contain some paraffins, he bases his classi-
fication on the content of other types of hydrocarbons,
dividing them into four classes —
(1) aliphatic oils
(2) aromatic oils
(3) naphthenic oils
(4) naphthelynic oils.
Bach of these may be subdivided into two classes, viz. thio-
and oxy-oils, according to the presence of oxy- or thio-
hydrols and/or ethers. He classes all solid bitumens as
"Petrolites," subdividing them into those soluble in carbon
bisulphide or asphaltites, and those insoluble in that solvent
or kerites, as these solid bitumens have undoubtedly been
derived from the corresponding classes of oils.
This work indicates the probability of being able to
predict the type of oil to be found in an underground reser-
voir from a study of the composition of the natural gas and
solid bitumens, which may be found in association therewith.
Such a result would be of great technical importance, quite
apart from the fact that a very profitable line of research is
also opened up.
30 PETROLEUM AND ALLIED INDUSTRIES
A rather interesting development during the last year
of the recent war was that of the extraction of helium from
natural gas. Certain natural gases were found to contain
small quantities of this gas, previously known merely as a
chemical curiosity. Though the helium content never
exceeded i *5 per cent, in the most favourable cases, and was
usually much lower, if present at all, plant was actually
set up for extracting this on the large scale, and at the date
of signing the armistice, many thousands of cubic feet had
been prepared.
GENERAL REFERENCES TO PART I., SECTION C.
Engler-Hofer, " Das Erdol," vol. i. Hirzel, Leipzig.
Lunge, " Coal Tar." Gurney and Jackson.
Malatesta, " Coal Tar." Spon. 1920.
Tinkler and Challenger, " Chemistry of Petroleum." Crosby Lockwood
and Son,
SECTION D.— GEOLOGY
THE geology of shales and coal is comparatively simple
and well known ; that of petroleum, on the contrary, is
difficult and presents many unsolved problems, not only in
specific cases, but in general. The origin of coals is invariably,
and of shales usually, attributed to accumulations of vege-
table matter or of vegetable matter and mud. Exactly what
changes took place accompanying the transition to coal or
shale is not yet understood. Coal and shale wherever found
occupy the same relative positions to the under- and over-
lying strata as they have always done since their deposition
They are, in fact, ordinary sedimentary rocks, they have
undergone the same tectonic changes as the adjacent strata
and the applications of geology to ordinary strata hold
equally well in their case. It is assumed, therefore, that the
reader is acquainted with the principles of geology and that
nothing more need here be said about the method of
occurrence of coals and shales.
As petroleum, however, is a liquid, the factors which
determine its accumulation are- much more complicated.
Petroleum is comparatively seldom found in its mother
rock, the strata in which it was formed ; migration has
usually taken place, so that the petroleum has either been
arrested and retained when suitable conditions existed, or
has escaped to the surface and been lost. This latter must
have been the case in innumerable instances. The question
of the ultimate origin of petroleum, therefore, may be
neglected in studying the conditions of its accumulation.
Petroleum in some form or another is found in all the
geological systems down to the Cambrian. About 50 per
cent., however, of the present production comes from
31
32 PETROLEUM AND ALLIED INDUSTRIES
Tertiary rocks, 40 per cent, from Carboniferous and Devonian,
and 8 per cent, from Ordovician.
The crudes of Ohio, Indiana, and Ontario are found in
the Ordovician and Silurian ; those of Pennsylvania in the
Devonian. Those of the Illinois and Mid-continent fields
occur in the Carboniferous, as does also the oil from the
Hardstoft well, recently brought in, in England. The oil
shales of Scotland also belong to this period. Certain of the
Wyoming oils belong to the Triassic, others to the Jurassic
period. The Kimmeridge and Norfolk shales of England
belong also to this system. Much of the crude of California,
Mexico, and Texas comes from the Cretaceous. The crudes
of the East Indies are of Tertiary age, as are also those of
Galicia, Russia, Burmah, and Egypt.
Bitumen in one form or another sometimes appears at
the surface in the form of (i) springs of natural gas, (2) lakes
or flows of asphalt, (3) seepages of crude oil, and (4) outcrops
of impregnated rocks.
Examples of (i) are afforded by the natural gas springs
of the Baku district, the gas from which has burned for
centuries. (2) The largest and most valuable forms of
semi-liquid asphalt occur in South America as the famous
asphalt (wrongly called pitch) lakes of Trinidad and Ber-
mudez. The native asphaltites, gilsonite and grahamite, are
found in veins outcropping at the surface. (3) Crude oil
seepages are common, and may be due to the oil-containing
rock actually outcropping at the surface or to the existence
of a fissure or fault through which oil can escape to the
surface. Such seepages are common in Mesopotamia,
Mexico, and elsewhere. The existence of seepages naturally
depends on the depths at which the main supplies of oil
occur, and on the degree of folding and Assuring to which the
rocks have been subjected. In the case of the Appalachian
fields of the eastern United States, for example, seepages
have seldom been found owing to the fact that the oil-bearing
beds have been only slightly tilted, and not at all broken
up. In other regions, such as parts of Mexico, seepages
are common, as the oil occurs in newer rocks which have
GEOLOGY 33
been tilted and eroded. In some cases undoubtedly the
oil may have almost completely escaped through fissures
formed by faulting. Interesting cases of seepages are those
in which the oil has been naturally filtered and decolorised.
Certain such " white oils " have been found in Persia,
Russia, and elsewhere. (4) Outcrops of rock impregnated
with oil or asphalt are also well known, good examples
being afforded by the so-called " tar sands " of Athabasca,
which are now attracting much attention, and the asphalt-
impregnated limestones of Val de Travers and L,immer, so
much used for street asphalt paving.
By far the greater quantity of the world's output of
bitumen is that of the liquid form, crude petroleum, and
this is obtained from strata at various depths by means of
borings or wells.
Liquid petroleum is invariably found in some more or
less porous rock, such as a limestone, or sandstone, which
acts as a reservoir. In some cases it is found in the mother
rock, i.e. that in which it originated, more often in some
rock into which it has migrated.
The question of the porosity and capacity for holding
petroleum of various rocks has been studied by several
authors. Beeby Thompson gives cases of sands capable of
holding 20 to 30 per cent, of their volume of oil, and Hager
reckons an average figure of about 13*5 per cent. A sand
may thus contain as much as a gallon of oil to the cubic
foot.
In all probability never more than 75 per cent, of the
oil from a rock surrounding the bottom of a well can be
recovered, and that only in the case of light oils.
The storage capacity of a rock for gas is, of course,
enormously greater, as the gas is often present under a
pressure of 500 Ibs. to the square inch or more. A rock
which could contain one gallon of oil to the cubic foot
could contain nearly 5 cubic feet of gas at 30 atmospheres'
pressure (Redwood, " Treatise on Petroleum," vol. i, 1913,
P- H3).
In addition to a suitable storage rock, another condition
P. 3
34 PETROLEUM AND ALLIED INDUSTRIES
is necessary, viz. a suitable impervious covering bed. A
fine-grained shale or clay, especially if wet, best fulfils the
conditions, as it is impervious and not liable to fracture.
Should such a covering exist, but be badly fractured, the
oil will usually have escaped. The Utica shale overlying the
petroliferous Trenton limestone affords a good example of
such a cover or cap-rock.
It is comparatively rarely that petroliferous beds are
found horizontal and undisturbed. In most cases the strata,
as the result of earth movements, have been folded into
anticlines or domes, the folds being sometimes complicated
by faulting. The folding of the strata has a great influence
on the accumulation of oil and gas in consequence of their
flnh'clme
FIG. i. — Diagrammatic section through anticlinal and synclinal folds.
fluid nature, and of their usual association with water.
Owing to lateral pressure brought about by earth move-
ments, the nature of which cannot be discussed here, the
once horizontal strata have been thrown into wave-like folds
or anticlines and synclines, the limbs of the folds being
highly or very slightly inclined according to the conditions
of the folding. The result of the superimposing of a series
of folds with axes more or less crossing the axes of the
original set, is a dome and basin structure similar to that of
many of the English coalfields.
These two types of structure are very common, but
cannot be said to be characteristic of oil-bearing territory.
In a field exhibiting such structure gas will be found accumu-
lated along the crests of the anticlines, oil below this and
GEOLOGY 35
water below the oil. If no water is, however, present, oil
may be found in the synclines too. Such a distribution of
the oil affords good evidence of movement or migration, the
factors controlling which are differences in specific gravity
and capillarity (M. R. Campbell, " Petroleum and Natural
Gas Resources of Canada." Canada Department of Mines,
1914). The anticlines are, however, often asymmetrical, one
limb of the fold being much steeper than the other. In
such cases, the greater portion of the petroleum will usually
be found in the gentler slopes.
Petroleum occurring under these conditions is often
found to be under great pressure. This pressure may be
due to : (a) artesian water pressure, (b) pressure of forma-
tion, the gradually accumulating gas having had no chance
of escaping. Advocates for both theories are found and
both theories may be correct. The latter view can, however,
account for all cases of pressure, the former only for a few.
This anticline type of structure predominates in most of
the oil-fields of the world, e.g. those of the United States,
East and Mid-continent, those of Russia, Burmah, and the
Dutch East Indies. Such folds being associated with moun-
tain chains, it is noticeable that most of the large oil-fields
of the world are found on the flanks of the main axes of
mountain formation.
Other types of structure of less common occurrence are
(a) the saline dome, (b) the igneous intrusion. The saline
dome type of structure is found in the fields of Louisiana .
Texas; and Rumania. These domes contain cores of crystal-
line salt, which have even, in some cases, been thrust up
through the overlying clays and sands, the structure being
then usually complicated by faulting. This is the case in
certain of the Rumanian fields. The structure and method
of formation of these saline domes is by no means as yet well
understood.
The igneous intrusion type of dome is found in Mexico.
The intrusion of a core of igneous rock evidently caused
elevation of the strata into domes which produced suitable
conditions for accumulation of petroleum. In some cases
36 PETROLEUM AND ALLIED INDUSTRIES
the intrusion of an igneous plug has caused tilting up of the
strata near the edges of the plug, and petroleum has accumu-
lated in these upturned edges, being sealed by the actual
intrusive plug.
In many cases petroleum is found in strata nearly hori-
zontal or only slightly inclined, provided that conditions of
sealing, which prevent a possible escape of the oil, exist.
Such conditions of sealing may occur in various ways. For
example, a petroliferous sand may thin out on a slope, being
sealed off by the coming together of the over- and under-
lying clays. Faulting may bring up a porous petroliferous
FfiUt-T.
FIG. 2. — Oil-bearing layer sealed by a fault.
rock against an impervious bed, and so make an efficient
seal (Fig. 2). Conditions suitable for petroleum accumula-
tion may be, and are, brought about in many different ways
of which the above afford a few examples only.
The detailed study of underground geological conditions
is of the greatest importance, not only for the exploitation
of new territory, but also for the selection of well sites in
known fields.
The discovery of many oil-fields has been in the first
instance due to so-called " wild catting," i.e. the sinking of
wells as a speculation. In many cases, however, it is only
by the making of test wells that an area can be proved
petroliferous or not. The choice of sites for such wells
GEOLOGY 37
should, naturally, always be guided by geological data as
far as possible. Even in a proved field wells may turn out
11 dry " owing to some unexpected geological feature, such
as a fault.
A careful correlation of the evidence afforded by the logs
of all wells may enable the contours of the underlying beds
to be plotted out, and the underground geology of the district
to be eventually thoroughly well understood.
GENERAL REFERENCES TO PART I., SECTION D.
Cunningham Craig, " Oil Finding." Arnold.
Emmons, " Geology of Petroleum." McGraw-Hill, New York.
Engler-Hofer, " Das Erdol," vol. 2. Hirzel, Leipzig.
Hager, " Practical Oil Geology." McGraw-Hill, New York.
Panyity, " Prospecting for Oil and Gas." John Wiley and Sons,
New York.
SECTION E.— THEOEIES OF ORIGIN
THE problem of the origin of petroleum is one, not only
of academic interest, but also of great practical importance.
It has received much attention during the last half -century,
has given rise to much discussion and a voluminous literature,
and is still regarded by many authorities as by no means
solved.
At the outset it may be pointed out that the problem
is complicated owing to the great differences in character
of different crude oils, and to the fact that in many cases
petroleums are found accumulated in rocks which were
certainly not their birthplace, but into which they have
migrated at some subsequent period.
Theories as to the volcanic or inorganic origin of petroleum
were advanced by Virlet d'Aoust and Rozet as far back as
1834, by Daubree in 1850, by Chantourcois in 1863. This
view was also held by Humboldt. Its chief advocate was
Berthelot, who in 1866 suggested that petroleum might be
produced by the action of steam on metallic carbides. This
theory was also advocated by Mendelejeff in 1877, who
considered that as carbides have been found in meteorites
they might also be expected to occur in the earth's interior.
There are no less than six meteoric stones which contain,
though in very minute quantity, carbon compounds of such
a character that their presence in a terrestrial body would
be regarded as an indirect result of animal or vegetable
life ("Introduction to the Study of Meteorites." British
Museum) . The modern production of carbides by the electric
furnace has added interest to this theory, but present-day
opinion is on the whole decidedly against it. The absence
of petroleum from the archaic formations also militates
against this view.
38
THEORIES OF ORIGIN 39
The presence of nitrogen bases and of complex organic
compounds which exhibit optical activity may be taken as
conclusive evidence that at least those petroleums which
contain such compounds are not of inorganic origin. Un-
less, therefore, further work or evidence in support of this
view be forthcoming, the inorganic theory must, in the vast
majority of cases at any rate, be considered untenable.
Theories as to the organic origin of petroleum fall into
two groups : (i) animal origin, (2) vegetable origin, both of
which have their ardent supporters.
Any theory worthy of consideration must fit in with
facts, must agree with the evidence both chemical, geolo-
gical, and experimental, and of the evidence, the geological
probably carries most weight.
The theory of the animal origin of petroleums rests
largely upon experimental work, often carried out under
conditions of temperature which certainly could never have
existed. In many cases, however, e.g. certain fields in
California, Egypt, Borneo, and elsewhere, geological evidence
is also in favour of an animal origin.
Warren and Storer, by the distillation of Menhaden oil
under pressure, certainly made kerosene oils and actually
marketed them. Engler (Ber., vol. 21, p. 1816 ; vol. 22,
p. 592) at a later date repeated these experiments and
obtained an oil distillate of specific gravity 0*815. After
removal of the unsaturated hydrocarbons from this product,
he obtained from it, by fractional distillation pentane,
hexane, octane, and nonane, together with a kerosene and
some paraffin wax.
Sterry Hunt, Briart, Orton, and others considered that
certain of the American crude oils found in limestones
originated therein from animal remains. Jaccard, from a
study of the Jura asphalts, arrived at the same view.
Objections to the animal theory origin have been raised
by Cunningham Craig, who points out that no accumulations
containing organic animal matter in any quantity are being
laid down at the present day. He points out further that
the animal contents of marine organisms are either devoured
40 PETROLEUM AND ALLIED INDUSTRIES
or decay away before accumulation is possible. While
admitting that such accumulations of animal matter are not
now forming, it is, nevertheless, possible and even probable
that conditions of rapid accumulation have obtained in the
past. In fact, there are many cases where the geological
evidence certainly points to animal sources.
Although the chemical distillations which have yielded
petroleum-like oils postulate high temperatures which are
obviously inadmissible, as often proved, for example, by
the close proximity of unaltered coal beds, it must be allowed
little is as yet known as to the nature of the chemical changes
which may take place at such high pressures as may easily
have obtained at considerable depth in the earth's crust.
The development of the study of high-pressure reactions
will, undoubtedly, throw further light on this question.
The possible action of bacteria is also a point which must be
considered. In many cases, undoubtedly, there are chemical
facts which cannot be reconciled with the theory of an
animal origin. Animal remains are relatively rich in
phosphorus. The association of phosphorus containing com-
pounds with petroleum is very unusual.
Although the geological processes going on at the present
day do not lend much support to the animal origin view,
and although the production of petroleum-like compounds
by distillation of animal matter really lends no support (as
the distillation of vegetable remains also yields similar
bodies), it can certainly not be asserted that in no instance
is petroleum of animal origin.
The theory of vegetable origin on the contrary rests on
much surer evidence. Vast accumulations of vegetable
matter have been formed and are now in process of forming.
Of the vegetable origin of coal there is no doubt. Shales,
coals, and lignites yield on distillation under suitable con-
ditions petroleum-like bodies. The postulation of the
necessary high-temperature conditions necessary for such
distillation is, however, inadmissible, and is perhaps
unnecessary.
Whether vegetable remains have passed under certain
THEORIES OF ORIGIN 41
conditions into coal, and under other conditions into
petroleum, or whether coal is a transition stage between
vegetable matter and petroleum, are questions as yet far
from settled. Cunningham Craig claims that the remains
of terrestrial vegetation which under other conditions would
develop into coal will, under certain conditions, result in
petroleum.
The nature of coal and its relation to petroleum are a
subject which has received much attention of late. Fischer
and Gluud (Ber., 1919, p. 1053) claim to have established
that certain light petroleum hydrocarbons do exist preformed
in certain coals. Mabery (/. Am. Chem. Soc., 1917, p. 2015),
from a consideration of the properties of vacuum distillates
from Deerfoot coal, is of the opinion that this coal is an
intermediate stage of decomposition between vegetable
remains and petroleum.
Hackford (Trans. Am. Inst. of Min. and Met. Engineers,
Sept., 1920), who has done much work on the constituents of
petroleum of high molecular weights, holds that petroleum
oils such as occur in nature are clearly not derived from coal,
but that petroleum may have been produced under certain
conditions from vegetable material containing no cellulose.
In the present stage of our knowledge, therefore, no
definite general explanation of the origin of petroleum
can be given. In certain cases, however, definite theories,
well supported by facts, can be advanced. For example,
Hackford (J.I.P.T., 1922, vol. 8) makes out a good case for
the derivation of Mexican petroleum from seaweed. The
outstanding features of Mexican petroleum are : —
(1) High sulphur content.
(2) Asphaltic nature.
(3) Minute nitrogen content.
(4) Ivow content of aromatics.
(5) Multiplicity of elements present in the ash of the oil.
There is ample sulphur in the alga Macrocystis pyrifera,
which is nowadays so abundant in the Gulf of Mexico, to
supply all that is necessary. Algae contain little or no
nitrogen. The practical absence of aromatics in the oil
42 PETROLEUM AND ALLIED INDUSTRIES
may be accounted for by the absence of cellulose in the
algae. The presence of numerous elements in the ash also
bears out this view. Different oils have undoubtedly origi-
nated in different ways, but the majority of crude oils are
probably of vegetable origin, the mechanism of formation
being not yet understood.
Further investigation and research are much needed for
the complete elucidation of these interesting and important
problems, especially in view of the fact that the available
world's supply of crude oil is decreasing. Eventually the
future of the petroleum industry can only be assured if the
processes of nature can be imitated or improved upon so that
vegetation, the pre-eminent agent for utilizing solar energy,
can be converted into petroleum, so convenient a source of
power, and so valuable as the source of innumerable indis-
pensable products.
GENERAL REFERENCES TO PART I., SECTION E.
Beeby Thompson, " The Oil-fields of Russia." Crosby Lockwood
and Sons.
Cunningham Craig, " Oil Finding." Arnold.
Dalton, " Economic Geology," IV. No. 7.
Devaux, " Des origines du petroles." L'age de Fer. May 10, 1920.
Gentil, " Origine des petroles." Chimie et Industrie. December, 1920.
Mabery, /. Am. Chem. Soc., 41, p. 1690.
Pascoe, " Memoirs, Geological Survey of India," vol. 40, Part I.
Sadtler, Peckham, Day, Phillips, Proc. Am. Phil. Soc., vol. 35, p. 93.
PART II.— NATURAL GAS
SECTION A.— OCCURRENCE, DISTRIBUTION,
AND COMPOSITION
THE term " natural gas " as generally used does not apply
to those effusions of nitrogen, carbon dioxide, sulphur
dioxide, etc., which are so common in almost every country,
and which are often associated with volcanic action ; nor does
it include gases often given off during the working of coal
seams. It is applied in this work only to those effusions
which are connected indirectly or directly with underground
supplies of petroleum.
It is often found escaping at the surface, as in the historic
case of the Caspian Sea area, where the " sacred fire " was
for long an object of religious reverence.1 It is the cause
of the curious " mud volcanoes " of Burmah and elsewhere,
which usually afford good evidence of the existence of
petroleum in the vicinity. The output obtained from such
natural springs is, however, comparatively insignificant.
From wells, on the contrary, bored either with the express
purpose of yielding gas or for liquid petroleum, the output
often attains stupendous figures.
It is much to be regretted that in the past countless
millions of cubic feet of this valuable fuel have been allowed
to run to waste, owing to the indifference of oil producers
and the lack of government regulations to ensure its conserva-
tion. The history of the industry is in fact an appalling
record of incredible waste.
It is estimated that in the few years prior to 1912 not
1 In this area it has long been used by the Tartars for burning lime.
Piles of limestone were made over gas vents or fissures, and the gas ignited.
When burning was complete the fire was extinguished by smothering with
sand.
43
44 PETROLEUM AND ALLIED INDUSTRIES
less than 425,000,000,000 cubic feet of gas were allowed to
escape in the Mid-continent fields alone. This amount is
equivalent in heating value to about gj million tons of fuel
oil. In 1913 a single well in the Gushing field yielded
1,500,000,000 cubic feet of gas before being shut in.
Beeby Thompson (J.I.P.T., vol. 8, p. 31) estimates that,
leaving out of consideration the fields which yield only
gas, 883,000,000,000 cubic feet of gas at least have been
dissipated into the atmosphere up to the end of 1920.
This is equivalent to a loss of 19,000,000 tons of oil, i.e. an
amount exceeding the total production of Rumania for ten
years.
In many cases, however, the loss has been unavoidable
owing to the unexpected finding of the gas at very high
pressures and the consequent running wild of the well.
In the majority of cases gas and liquid petroleum are
closely associated, often occurring in the same beds. In
many cases, however, gas is found in very large quantities
in beds which yield little or no oil.
The North American continent yields by far the greater
proportion of the world's total output of natural gas, and it
is, therefore, in this area that the natural gas industry finds
its greatest development. The chief producing fields are
those of West Virginia, Pennsylvania, and Ohio, which alone
produce about 600,000,000,000 cubic feet per annum.
California, Iyouisiana, Kansas, and Texas, produce also in
considerable quantities. Considerable quantities of gas
have also been produced in Ontario ; also in Alberta, where
the output reaches 75,000,000 cubic feet a day. A certain
output of gas is obtained from most oil-fields, so that apart
from the gas-fields of the North American continent, the
occurrence and distribution of natural gas may be taken as
coincident with that of crude oil (vide Part III.).
As will have been gathered from the introductory section,
the gas, when confined in an anticlinal or dome structure, lies
in the crest of the fold, the oil lying on the flanks beneath.
Care must therefore be selected in choosing sites for wells.
These should be drilled on the flank of the anticline or dome
NATURAL GAS 45
into the oil zone, avoiding that portion occupied by the gas.
A well drilled at A (Fig. 3) will penetrate the gas zone and
will not yield oil until all the gas has been withdrawn. A
well drilled at B will, on the contrary, yield oil, and this
well will flow, the oil being ejected by the pressure of the
gas, which latter will not appear in the well until much of
the oil has been removed.
The gas is, in this case, not only conserved but is utilized
for the ejection of the oil, pumping being thus unnecessary.
The site of a well can, however, not be so carefully
selected until the confines of the underlying oil pool have
been well delineated, and this unfortunately cannot be done
in the early history of a field, when the gas is present in
greatest quantity.
In the Appalachian fields of the United States vast
gas-fields exist in the Palaeozoic rocks, the strata of which
are very slightly inclined, so that the fields cover a large
area. This gas is particularly " dry," containing small
quantities only of condensable constituents.
The gas is often found under great pressure, 500 Ibs.
to the square inch being quite usual. Pressures as high as
1500 Ibs. have actually been recorded. When the gas zone
is entered accidentally, or sooner than anticipated and
before adequate precautions have been taken, the heavy
boring tools and cable are often shot out of the well with
great violence.
Gas wells of 40,000,000 or 50,000,000 cubic feet per day
have often been drilled, and in a few cases an initial output
of over 100,000,000 cubic feet has been estimated.
Natural gas was utilized for illuminating purposes in
the United States as far back as 1826. In the early days of
the industry huge gas flares were used for illuminating the
fields, and usually burned day and night. It was also largely
used as fuel for the drilling boilers, but practically only a
small percentage was so utilized, the greater quantity being
allowed to run to waste. It is only during the last decade
or two that the value of this gas has been realized, and efforts
made to conserve the supplies.
'I,
XX
NATURAL GAS 47
Quantities of gas are usually given off by flowing wells
when yielding oil, the gas in such cases being often separated
from the oil by means of special " separators " or " gas
traps " and utilized. Natural gas obtained in this way is
usually rich in condensable components and is known as
" casing-head gas/'
Natural gases consist for the most part of methane and
other hydrocarbons of the paraffin series ethane, propane,
butane, etc. Carbon dioxide and nitrogen are also usual
constituents, but generally in small quantities. Oxygen,
carbon monoxide, and hydrogen are rarely, if ever, present.
There is, however, very great variation in composition.
The dry gas of the fields of Pennsylvania contain about
80 to 90 per cent, of methane, about 10 per cent, of ethane,
and 2 or 3 per cent, of propane. Nitrogen is often present
to the extent of a few per cents., but in certain cases, e.g.
that of the Dexter well in Kansas, it constitutes the bulk of
the gas. In certain Californian gases, the percentage of
carbon dioxide rises to about 30. The wet or rich gases
which escape from wells which are yielding oil naturally
contain greater percentages of the heavier, more easily
condensable hydrocarbons, such as butane, pentane, and
hexane.
Several of the natural gases of Kansas, Texas, and Canada
are remarkable in that they contain traces of helium and
other gases of that family. As much as 1*8 per cent, of
helium has been found in rare cases, and indeed this element
has actually been prepared on a large scale from natural gas
(McLennan, /.C.5., vol. 118, p. 923).
The natural gas industry has been developed mainly
in the United States and Canada, which, together, yield over
95 per cent, of the world's output. The extent of the gas-
fields in the U.S. has been put at over 9000 square miles.
Production figures for the early days of the industry are not
available, but between 1906 and 1918 it is reckoned that the
quantity produced and consumed amounted to 7^ trillion
cubic feet. The total volume actually produced, much of
which is unrecorded, must have been much larger. The
48 PETROLEUM AND ALLIED INDUSTRIES
actual production in 1918 was 720,981,141,000 cubic feet,
that in 1917 (the highest recorded) was 795,110,376,000 cubic
feet being produced by 39,370 wells. The production in
1919 showed a further slight decline. The bulk of the gas
has come from Virginia, Pennsylvania, Oklahoma, Kansas,
Ohio, California, and New York.
SECTION B.— APPLICATIONS
I/ESS than a score of years ago the natural gas industry
may be said to have been non-existent. Its recent develop-
ment is partly due to the introduction of legislative measures
for minimizing waste, partly to the rapidly growing demand
for motor spirits, and to the finding of new applications.
In many fields where gas is found under pressure, it
is used instead of steam for driving the drilling and pumping
engines, the exhaust gas being further utilized as a fuel for
steam generation, and for the domestic needs of the camp.
It is, moreover, often collected and pumped to adjoining
towns and used for illuminating, heating, and power purposes.
Many towns in America are well supplied with cheap power
in this way, the gas being often retailed at prices as low as a
few pence per 1000 cubic feet.
The heating values (gross) in B. Th. Units for one cubic
foot of various gases at o° C. and 760 mm. pressure are : —
Methane . . Sp. gr. 0-553 • • • • I0^5
Ethane . . „ 1*049 • • • • I^^1
Propane . . „ 1*520 . . . . 2654
Butane . . „ 2*004 . . . . 3447
Pentane . . . . . . 4250
i cubic metre of average natural gas may be taken as
equivalent to 1*5 Kgs. coal as regards heating value.
A very important product derived from natural gas
is carbon-black. This is an amorphous form of carbon or
soot produced by the incomplete combustion of natural
gas. It is not to be confused with lamp-black, which is an
inferior material made by the combustion of turpentine,
resin, or such bodies. Carbon-black is much superior to
p. 49 4
50 PETROLEUM AND ALLIED INDUSTRIES
lamp-black as a pigment — in fineness, miscibility with oil,
and covering power. A cubic inch of carbon-black is esti-
mated to have a surface of 1,905,000 square inches, the
same volume of lamp-black having only 1,524,000,
It is manufactured by burning natural gas with a limited
supply of air under such conditions that the carbon, which is
produced in the inner part of the flame where the temperature
is sufficiently high to decompose the gas, but where the
oxygen supply is low, is quickly cooled by being deposited
on a cooled surface.
Three types of plant, using the disc, plate, and cylinder
processes are in common operation, the principle underlying
each being the same (Roy. O. Neal, Chem. and Met. Eng.,
1920, p. 785).
In the disc or Blood process, the gas is burned and the
flames allowed to impinge on a cast-iron rotating disc of
3 to 4 feet in diameter, the carbon-black being scraped off
into a hopper as formed. In the plate or Cabot system, a
large number of plates are arranged horizontally in a circle.
The burners and scrapers revolve underneath the plates on
a central axis. In the roller system devised also by Blood,
the flames impinge on rotating rollers, from which the
carbon-black is scraped off. This system produces a black
of better quality, but the yield is smaller.
All these processes produce only about 0*8 to 1*4 Ibs. of
carbon-black per 1000 cubic feet of gas burnt. They appear
very wasteful methods, but are apparently the only practical
processes known which produce the carbon-black most sought
after by the printing trade.
The quantity of carbon-black produced in the U.S.A. in
1920 amounted to 51,321,892 Ibs. For the manufacture of
this quantity 40,600,000,000 cubic feet of gas were consumed,
the average yield per 1000 cubic feet of gas thus amounting
to 1*26 Ibs.
Thirty-nine plants in all were in operation. The
producing States and their percentage output were West
Virginia 52, Louisiana 36, Wyoming, Montana, and Kentucky
together n, and Pennsylvania i.
APPLICATIONS OF NATURAL GAS 51
Carbon-black is used primarily for the manufacture of
printing ink. One pound of carbon-black will suffice to
print 2250 copies of a sixteen-page newspaper. About
35 per cent, of the entire output is used for this purpose.
It is also largely used in the rubber tyre industry. The
addition of carbon-black renders the rubber more resilient.
It increases the tensile strength of the rubber by about
25 per cent, and the elasticity by about 10 per cent.
About 10 per cent, of the total production is used for
stove polishes, I per cent, for gramophone records, and
large quantities for paper manufacture, Chinese and Indian
inks, marking inks, boot polishes, tarpaulins, varnishes,
etc. (Perrot and Thiessen, J. Ind. and Eng. Chem., vol. 12,
P- 325).
The great value of the condensable portions of natural
gas for admixture into motor fuels has given rise to an impor-
tant industry of recent years. In 1903 motor spirits were
first collected from the condensates in natural gas pipes,
and in 1905 the first plant designed for the specific purpose
of recovery of these valuable volatile spirits from natural
gas was erected. Since that date the development has been
considerable. In 1914, in the United States alone 386
plants were in operation, treating about 17,000,000,000
cubic feet of gas and obtaining therefrom 42,650,000 gallons
of light motor spirit. In 1920 the quantity had increased
to 383,311,817 gallons, an amount which was extracted
from 495,883,700,000 cubic feet of gas, an average of 077
gallon per 1000 cubic feet. Nearly 75 per cent, of this
was extracted by the compression process. This amount
represents nearly 8 per cent, of the total output of the United
States of motor spirits for that year. The industry has been
developed in other fields in other parts of the world, but
as it is primarily an American industry, the American term
" Casing-head gasoline " will, in future, be used to desig-
nate the product, this name having come into general use in
the petroleum industry.
In addition to the natural gas obtained from gas wells,
much casing-head gas also flows together with crude oil from
52 PETROLEUM AND ALLIED INDUSTRIES
oil wells, this gas being consequently richer in benzine
(gasoline). Gases are usually designated " dry," "lean,"
or " wet " according to their gasoline content.
" Dry " gases are composed chiefly of methane and
ethane and yield no condensable portions; "lean" gases
contain also proportions of propane, butane, and pentane ;
and " wet " gases contain also proportions of the vapours
of hexane, heptane, and perhaps some of the more volatile
naphthene hydrocarbons, e.g. hexa-methylene.
Two methods of treatment for the extraction of casing-
head gasoline are in general use, the compression and
absorption methods, the former being usually applied to
rich, the latter to lean gases.
The Compression Process. — The gas is pumped from
the fields and after passing through a drip tank (i) to trap
any condensed gasoline, enters the low-stage compressors (2).
FIG. 4. — Diagram illustrating operation of compression gasoline plant.
After compression it passes through the cooling coils (4),
and then goes on to the high-stage compressors (6). After
further compression it passes through the cooling coils (7).
The gasoline which separates out is drawn off from the
separating tanks (3 and 5). The cooled compressed gas then
APPLICATIONS OF NATURAL GAS 53
goes on into the regenerative expansion coils (n) and expan-
sion motor (9) , the exhaust from which passes back through
the regenerator expansion coils (n). Compressors of any
well-known type are used, the gas being compressed up to
20 to 50 Ibs. per square inch in the low-pressure stage. The
gas, heated by compression, is then cooled, a certain amount
of condensate being formed which is separated off, depending
of course on the nature of the gas under treatment. The
gas is then further compressed in the second set of compressors
up to as much as 300 Ibs. per square inch or more. The
gas, now at a temperature of perhaps 250° C., owing to the
compression, is again cooled. In the second set of coils, a
further quantity of condensate separates out. The residual
gas is then further cooled by expanding and doing work in
an expansion motor, the cold exhaust from which further
cools the gas on its way to the motor, so that a further
condensate is obtained.
General practice shows that a gas of sp. gr. 0-9 (air=i)
is about the leanest which can be successfully handled
by a compression plant.
The gasoline obtained is too volatile (and too valuable) for
general use, and is consequently used for blending with heavier
grades of gasoline to make motor spirits. Mixtures contain-
ing a large quantity of such compressor gasoline, suffer much
evaporation loss on standing, e.g. a mixture of 50 per cent,
compressor gasoline of sp. gr. 0*630, and 50 per cent, gasoline
of sp. gr. 0739 on standing in an ordinary graduated litre
cylinder for one hour lost 4 per cent, by evaporation.
The Absorption Process. — The first absorption plants
were installed on the gas transmission lines for absorbing
as much as possible of the condensable vapours in order to
avoid the deterioration of the rubber jointings and the
formation of condensed liquid in the line pipes. The installa-
tion of such drying absorption plants is commercially
justifiable on these grounds alone.
Much natural gas contains too little gasoline for extraction
by the compression system (f gallon gasoline per 1000 cubic
feet is the practical minimum), but may be economically
54 PETROLEUM AND ALLIED INDUSTRIES
<5fts OUTLET
treated by an absorption
plant, even if the gaso-
line content is as low as one
pint per 1000 cubic feet.
The operation of an
absorption plant is similar
to that of the benzol wash-
ing plants, so largely used
during the war, for the
recovery of benzol from
coal gas.
The natural gas is
passed through a series of
absorption towers where
it meets a descending
stream of non - volatile
distilled oil, which dis-
solves out the condensable
portions of the gas. The
gasoline is then recovered
from solution in the heavy
oil by distillation, the
gasoline - free heavy oil
being used over again.
The factors which control
the design of the plant
are pressure, temperature,
gasoline content of the
gas, time of contact with
the absorbing medium
together with the nature
of the tower packings,
and other such details
which affect the efficiency.
The higher the pressure,
the §«*** the absorp-
tion, but too great an
absorption means too great a loss by evaporation when the
4O/J. OUTLET
APPLICATIONS OF NATURAL GAS 55
gasoline is subsequently distilled and blended. The lower
the temperature, the better the absorption. The intimacy
of contact is affected by the nature of the tower packing,
and the time of contact must be sufficiently long.
The absorbers in most general use are of the vertical
tower type. I^ean gases are treated at higher pressures
than are rich gases, so the construction of the tower must
be arranged for accordingly. They are usually constructed
of diameters up to 12 feet and of height 20 to 60 feet or
more (Fig. 5).
A grating, on which the filling rests, is placed a few
feet above the bottom, the gas being introduced by a pipe
entering below the grating. The absorbing oil is introduced
a few feet below the top of the tower, being distributed over
the surface of the packing by a perforated pipe. The
extracted gas outlet and solution outlet are placed at the
top and bottom of the tower respectively. Several towers
are usually arranged in series and connected by piping
so that any one can be by-passed for repairs without shutting
down the plant. The towers are designed so that the
velocity of the gas is from 30 to 75 feet per minute in the
unpacked portion of the tower.
The towers are filled with wood gratings, cobbles or
other form of packing. The modern forms of packing such
as Raschig rings or those of the types used in acid absorp-
tion towers would certainly be more efficient, as the surface
presented per cubic foot of volume is so much greater.
The oil used for absorbing is generally a heavy distillate,
such as gas oil, heavy kerosene or light lubricating oil
fractions. The initial boiling point of the absorbing oil
should be much higher than the final boiling point of the
absorbed gasoline, in order to render the subsequent separa-
tion by distillation as easy and effective as possible.
The absorbing oil should also be of low viscosity and of
a type which does not readily emulsify. It should be cooled
as far as possible before entering the tower. For this purpose
cooling coils immersed in water are usually used. About
3 or 4 square feet of cooling surface per gallon of oil per
56 PETROLEUM AND ALLIED INDUSTRIES
minute is usually allowed, but this of course depends on the
temperature of the incoming oil.
When the gasoline content in the oil rises to about
4 per cent, the absorbing power begins to fall off. The
amount of oil circulated varies enormously in practice
according to conditions and the character of the gas, from
3 or 4 gallons to as much as 70 per 1000 feet of gas, 7 to 10
being the usual figure.
After leaving the towers (i) the oil flows into the
" weathering tanks," (2) where it is allowed to stand at a
reduced pressure in order to give up some of the gas which it
FIG. 6. — Diagram illustrating operation of absorption gasoline plant.
dissolved in the tower. This gas could not be recovered as
gasoline by distillation and is usually not sufficiently rich for
retreating. It is passed on into the extracted gas mains with
the rest of the treated gas.
From the weathering tank the oil is passed through the
heat exchangers (3), to the still (4), where the dissolved
gasoline is distilled off and condensed, the gasoline-free
oil returning via the heat exchangers and the cooling coil (5),
to the top of the absorption tower (i). The same absorbing
oil is thus used over and over again, a small amount of make-
up oil being added from time to time to balance unavoidable
losses.
APPLICATIONS OF NATURAL GAS 57
The heat exchangers used are of the ordinary types,
for a description of which reference may be made to
Part VII., Section A.
Any of the ordinary types of still may be used, as the
operation of separating the volatile gasoline from the heavy
absorbing oil is very simple. The ordinary form of steam
redistillation still is often used, the oil from the absorber
being admitted into the column. A simple vertical still
fitted with steam-heated baffle plates and supplied with a
live steam coil at the bottom would also serve quite well.
For details as to still construction reference may be made to
the section on "Distillation of Crude Oil" (see Pt. VII.,
Sec. A). Fire-heated stills are however rarely used.
The gasoline produced from absorption plants has a
higher specific gravity and a lower vapour pressure than
has compression gasoline owing to its lower dissolved gas
content. It naturally also possesses none of the heavy
fractions found in gasoline distilled from crude. About
80 per cent, of the product may be expected to boil over
below 100° C. in an Engler flask, and the final boiling point
will be under 150° C.
Absorption plants are, on the whole, more efficient and
much cheaper in operation than those of the compression
type. An absorption plant can indeed be operated suc-
cessfully on the exhaust gases from a compression plant,
and several such plants have been installed. The gasoline
from absorption plants, moreover, loses relatively less by
evaporation on standing than does compressor gasoline.
A modification of the absorption plant which is sometimes
used, consists in replacing the absorbing oil by heavy
benzine, so that this benzine becomes lighter and more
volatile and is used for blending, the distillation process
being thus avoided. This type of absorbing plant is often
used in connection with the recovery of vapours given off
during the distillation of crude oil or distillates, the distilling
loss being in this way considerably reduced.
In addition to the two processes above described there is
a third which has so far not found extensive application,
58 PETROLEUM AND ALLIED INDUSTRIES
but which gives good promise of future development. It
is based on the absorptive power of charcoal (Anderson and
Hinckley, J. Ind. and Eng. Chem., vol. 12, 1920, p. 735 ;
Oberfell, Sprinkle, and Meserve, ibid. vol. n, 1919, p. 197 ;
Burrell and Oberfell, Oil and Gas Journal, July, 1920, p. 84).
Three vertical absorbers 20 to 35 feet high and 2 to 3 feet
diameter are used. They are packed with a special porous,
granulated charcoal. The gas is passed through the first
absorber until the charcoal is saturated, and is then passed
into the second, the gasoline being distilled out of the first
by means of steam. Each unit acts, therefore, both as
absorber and still. The charcoal lasts indefinitely and
indeed its action improves with use. A portable apparatus
for the examination of natural gases in the field, based on
this action of charcoal, has been designed.
In 1907 Cady and McFarland (/. Am. Chem. Soc., vol.
29, p. 1523) had already discovered the presence of
helium in Kansas natural gas, In 1916, a survey of most
of the available natural gases in the British Empire was
made, and it was found that certain gases from Ontario
and Alberta, Canada, contained this gas in quantities up to
036 per cent. Certain gases in Texas, however, contain
nearly 2 per cent. The superiority of helium over hydrogen
as a gas for filling airship envelopes, and the urgent need
for supplies at any cost, gave rise to a wonderful helium
industry, which at the date of signing of the armistice in
1918 was a technical and almost a commercial success.
The method used for the extraction of the helium was that
of producing refrigeration sufficient to liquefy all the gases
except the helium, this method being applied in the Norton
plant, similar in general to the Claude oxygen-making plant
(Mcl^ennan, J.C.S., vol. 107, p. 20, p. 923).
Helium of 97 per cent, purity was obtained at a cost of
as low as 2%d. per cubic foot, a notable achievement indeed,
considering that but a few years ago helium was merely
a chemical curiosity.
It has been estimated that the United States alone could
produce nearly a million cubic feet of helium daily.
APPLICATIONS OF NATURAL GAS 59
GENERAL REFERENCES TO PART II., SECTION B.
Burrell, Biddison and Oberfell, " Extraction of Gasoline from Natural
Gas by Absorption Methods." Bulletin 120, U.S. Bureau of Mines.
Burrell and Oberfell, " Composition of Natural Gas." Technical Paper
109, U.S. Bureau of Mines.
Burrell, Siebert, and Oberfell, " Condensation of Gasoline from Natural
Gas." Bulletin 88, U.S. Bureau of Mines.
Dykema, " Recovery of Gasoline from Natural Gas by Compression."
Bulletin 151, U.S. Bureau of Mines.
Dykema, " Recent Developments in the Absorption Process." Bulletin
176, U.S. Bureau of Mines.
Dykema and Neal, " Absorption as applied to Recovery of Gasoline
left in Residual Gas from Compression Plants." Technical Paper 232,
U.S. Bureau of Mines.
Henderson, " The Natural Gas Industry," J.I.P.T., vol. 2, p. 195.
McLennan, " Some Sources of Helium in the British Empire." Bulletin
31, Canadian Department of Mines.
Westcott, " Handbook of Casing-head Gas." Metric Metal Works,
Erie, Pa.
Westcott, " Handbook of Natural Gas." Metric Metal Works, Erie,
Pa.
PART III.— CRUDE PETROLEUM
SECTION A.— OCCURRENCE, DISTRIBUTION,
AND CHARACTER
BITUMEN in its liquid form has been found in almost every
country of the globe, in many cases, however, only in small
quantities incapable of commercial exploitation. As about
65 per cent, of the earth's land surface is made up of sedi-
mentary rocks, and as enormous areas have not yet been
examined, the possibilities of future development are great,
even when taking into consideration the limitations arising
from the need of the existence of tectonic structures suitable
for petroleum reservoirs.
The recent discovery of oil in Northern Canada (Oil News,
1920, p. 1051) undoubtedly foreshadows many such develop-
ments in the near future*
Although so widely distributed, the bulk of the world's
supplies up to the present have been drawn from a relatively
small number of important areas, many of which have already
reached their peak production. Certain fields of Russia
and the United States have produced steadily for half a
century ; fields discovered at later dates, e.g. those of Mexico
and Persia, are now important producers ; others, e.g. those of
South America, are as yet in their infancy. Crude oils from
different fields show great variation in character, as is only
to be expected from the fact that they are drawn from strata
of very varying geological ages, and have been formed in
varying ways, from varying materials.
In many cases, therefore, as might be expected, a field
yields different types of oils from strata at different depths,
e.g. those of Alsace and East Borneo, though, broadly speaking,
the crudes of any one field usually belong to one type, in
many cases quite characteristic of the particular field.
60
CHARACTERS OF CRUDE OILS 61
The main producing fields with the chief characters of
their crudes are detailed below.
Although crude oils vary enormously in character from
the remarkable white oils (which are naturally filtered oils
of comparatively rare occurrence and of no economic
importance), and the very light oils rich in volatile fractions,
such as those of Sumatra, to the heavy viscous oils found in
parts of Mexico, they may be divided roughly into three
main groups, (a) the paraffin-base oils, (b) intermediate-
or mixed-base oils, and (c) naphthene- or asphalt-base
oils. These last two groups are usually included in the
term " asphalt-base oils/'
Paraffin-base crudes are those containing relatively
high percentages of aliphatic hydrocarbons, naphthene-base
oils those containing relatively high percentages of cyclic
hydrocarbons.
Distillates of a given boiling range from paraffin-base oils
have a lower specific gravity than do those of similar boiling
range from naphthene-base oils. Also paraffin-base dis-
tillates are of lower viscosity than naphthene-base distillates
of the same boiling-point range, or, expressed in another way,
naphthene-base oils have lower flash-points than paraffin-base
oils of the same viscosity (Dean, Nat. Pet. News, 1921, p. 24A).
The term " paraffin-base crude " is often used to mean,
containing relatively large percentages of paraffin wax.
Numerous inconsistencies will be found to occur, e.g. the
distillates of certain types of Borneo crude, which are
certainly rich in paraffin wax, are of very high specific
gravity owing to the presence of relatively large quantities
of aromatic hydrocarbons.
The Appalachian field, once the most important, is
the oldest field in the United States. It includes all the
fields east of Central Ohio, i.e. those of Pennsylvania, New
York, Kentucky, South-east Ohio, North Alabama, Tennessee,
and West Virginia. The crudes from this area are of the
paraffin-base type, and are of Devonian and Carboniferous
age. They contain as a rule 2 to 3 per cent, of paraffin
wax. They are of light specific gravity, usually varying
62 PETROLEUM AND ALLIED INDUSTRIES
from 0*790 to 0*825. They consist, for the most part, of
saturated hydrocarbons of the paraffin series. They are
relatively free from sulphur, rich in benzine, and yield good
lubricating and cylinder oils.
The ratio carbon/hydrogen is the lowest, viz. 6*2.
The crudes of the Lima-Indiana field, comprising
Indiana and North-west Ohio, are of similar nature, but are
contaminated with sulphur compounds, which make the
refining of these oils more difficult. They are of somewhat
higher specific gravity as they contain hydrocarbons other
than paraffins. They are of Ordovician, Silurian, and Car-
boniferous age.
Those of the Illinois field are of naphthene-base, but
also contain some paraffin wax. They contain small per-
centages of sulphur compounds. They are mostly of
Carboniferous age.
The fields of Oklahoma, Kansas, Louisiana, and North
Texas are usually grouped as the Mid-Continent field.
Several types of crude are here found, both of asphalt-
and paraffin-base, with varying per cents, of sulphur, and
varying benzine content. They resemble on the whole the
crudes of Texas and California rather than those of the
Appalachian type. They occur in Tertiary, Cretaceous, and
Carboniferous strata.
The Gulf field includes those of South Texas and
South Louisiana. These fields yield oils of several types,
both light oils of sp, gr. 0*820 to 0*850, somewhat similar to
those of Ohio, of a mixed-base type, and heavy oils of
sp. gr. 0*920 to 0*970 containing no paraffin wax. They are
mostly of Cretaceous and Tertiary age. These oils contain
hydrocarbons of the series CnH2w— 2 an(i CwH2w_4, terpenes
and naphthenes.
The carbon/hydrogen ratio is about 6*9, and sulphur
is present in amounts up to 2 per cent.
The Rocky Mountain area includes the fields of
Colorado, Wyoming, Utah, New Mexico, and Montana.
These crudes are of naphthene-base type and of Carboniferous
and Cretaceous age.
OCCURRENCE OF CRUDE OIL 63
California is now the chief producing state. The oils
from its many fields differ very considerably. Those from
the earlier known fields were of high specific gravity and of
high asphaltic content, though latterly lighter oils have been
found. The sulphur content varies, but is usually below
i '5 per cent. California crudes are mostly of Miocene
age.
The production of the United States amounts to about
65 per cent, of the world's output.
The fields of Mexico may be divided into two main
areas : — The Gulf zone comprising the Ebano, Panuco,
Topila, lyos Naranjos, Potrero, and Alamo fields; the
southern zone comprising the Tehuantepec and Tabasco
districts. Production, however, practically all comes from
the Gulf zone.
Two types of crude are found : (a) a light crude of a
mixed-base type, containing paraffin wax and asphalt,
and a heavy asphaltic type. These crudes resemble each
other in that their volatile constituents are composed
mostly of hydrocarbons of the paraffin series. They are
very rich in sulphur, containing up to about 5 per cent.
I/ight Mexican crude (sp. gr. 0*925) yields about 15 per
cent, of benzine, 7 per cent, of kerosene, gas oil and lubricating
oils of good quality, and asphalt or coke.
(b) A heavy crude of high specific gravity (about 0-980),
which yields only a small percentage of benzine. This
yields excellent asphalts of various grades and heavy liquid
fuels.
The oils of Venezuela are also of high specific gravity
and of the asphalt-base type ; they yield only small quantities
of benzine and kerosene, and are used mainly for liquid
fuel. They contain about 2 per cent, of sulphur.
Trinidad produces a considerable quantity of crude
petroleum apart from that of asphalt from the famous lake.
The crude oils are of the naphthene-base type, those from
the deeper sands being of lower specific gravity than those
from the shallower strata. Mixed-base oils have also been
found.
64 PETROLEUM AND ALLIED INDUSTRIES
The production of crude petroleum has never reached
a high figure in Canada, though great efforts have been made
to encourage the industry. Several small fields in Ontario,
e.g. those of Oil Springs and Petrolia, have already passed
their zenith. The oils are similar to those of Ohio, containing
about i per cent, of sulphur. They consist for the most
part of saturated paraffins, but contain hydrocarbons
relatively poorer in hydrogen in the higher fractions*
Very large deposits of asphaltic sands (usually wrongly
termed tar-sands) are found in Northern Alberta, outcropping
on the banks of the Athabasca and other rivers (S. C. Klls,
" Bituminous Sands of Northern Alberta," Dept. of Mines,
Canada). These sands contain from 7 to 20 per cent, of
soft asphalt (Krieble and Seyer, /. Am. Chem. Soc., 1921,
P- 1337)-
Peru produces an oil of naphthene-base type, in consider-
able quantities.
The Argentine Republic is developing a crude oil
production from four distinct fields. The oils are similar
in character to those of Peru.
Brazil has potential areas which have not yet been
developed, and Bolivia and Colombia have so far received
little attention.
The country which has played the second most important
part in the development of the petroleum industry is Russia.
The two chief oil-producing areas are the Caucasus and
the Ural Caspian. The oils are mostly of Miocene age.
The production of the Russian fields from 1910 to 1916
was at the rate of 10,000,000 tons per annum. The present
disturbed political condition of the country (1921) has
caused a reduction in output to about one-third of this
figure.
The oils from the Balachany, £aboontje, Romany,
Surachany, and Bibi-Eibat fields contain little or no
paraffin wax, and are composed largely of hydrocarbons of
the naphthene type. They yield good lubricating oils of
low cold test, and good non- viscous liquid fuels.
The Grosny fields produce crudes of two types, the
OCCURRENCE OF CRUDE OIL 65
one almost free from paraffin, the other relatively rich (about
5 per cent.). These crudes are also rich in naphthenes and
contain aromatic hydrocarbons in small quantities.
The Maikop fields 3'ield crudes rather richer in volatile
constituents than those of the other Russian fields. The
content of paraffin wax is low (about 0-5 per cent.), and
aromatic hydrocarbons are present.
Rumania possesses several important fields which yield
several types of oil. These crudes generally consist of hydro-
carbons of the paraffin, naphthene, and aromatic series,
with small proportions of terpenes. The presence of aromatic
hydrocarbons lowers the burning quality of the kerosenes.
The crudes of Bustenari, Campina, Baicoi, and Tzintea
contain paraffin wax in quantities up to 7 per cent.
The crude oils of Galicia are intermediate in character
between those of East North America and of the Russian
Caucasus. Those of Bast Galicia contain paraffin wax up
to 12 per cent., those of the West are nearly paraffin-free.
They are usually practically free from sulphur. They are of
Cretaceous, Eocene and Oligocene age.
There are fields of relatively minor importance in Alsace
(Pechelbronn) . Oil has been found also in Italy, France,
Spain, and Greece. It is of particular interest to note that
the test well recently put down in England (Derbyshire)
has produced several hundred tons of a remarkable oil.
The Derbyshire (Hardstoft) crude is of low sp. gr. 0*823,
greenish brown in colour with marked fluorescence. It
yields 17 per cent, of motor spirits and 30 to 40 per cent,
of excellent kerosene (0785 sp. gr.). The residual oil after
removal of benzine, kerosene, and gas oil is a cylinder oil of
remarkable quality, containing no asphaltic matter, similar
in properties to a Pennsylvanian filtered cylinder oil. The
crude contains also about 3! per cent, of paraffin wax.
In Asia important oil-fields have been exploited in
Persia, Burmah, and the Dutch East Indies. Less
important fields exist in Japan and Assam. Large fields
probably exist in Mesopotamia, and various parts of Siberia,
but these have not yet been exploited.
P. 5
66 PETROLEUM AND ALLIED INDUSTRIES
The crude oils of Persia consist of hydrocarbons of
the paraffin series, with smaller quantities of naphthenes.
Aromatic hydrocarbons are also present. They contain
also sulphur compounds. They are rich in volatile fractions,
yielding 20 per cent, or more of motor spirits.
The Burmah crude oils are rich in paraffin wax. They
consist of hydrocarbons of the paraffin series, with members
of the naphthene series and aromatics also present in
considerable proportions.
The potentialities of Mesopotamia as an oil-producing
country are undoubtedly great, but have not yet been
adequately examined. Oil is produced in trifling quantities
near Mosul and at Mandali on the Persian frontiers. The
oil is similar to the crudes of Mexico in character, and is
rich in sulphur compounds.
In the Dutch East Indies many important fields are
found. North and South Sumatra produce light oils, very
rich in benzine and kerosene fractions. Those of North
Sumatra are of paraffin-base, those of the South of asphaltic-
base. Both types contain appreciable percentages of
aromatics and considerable percentages of naphthene
hydrocarbons. Oils of very varying character are found in
Java. The fields of East Borneo (Koetei) produce three
types of crude, heav}' asphalt, light asphalt, and paraffin
wax base oils. The crudes of the Koetei field are remarkably
rich in aromatic hydrocarbons, as much as 40 per cent,
being found in the volatile fractions of the crude. Those of
the Tarakan field are paraffin-free, as are also those of the
Sarawak fields. These latter are very rich in hydrocarbons
of the naphthene series.
Japan possesses several small fields which yield oils
of varying character.
Africa has up to the present only one producing field,
that of Egypt on the coast of the Red Sea. Preliminary
work is, however, being carried on in Algeria.
The Egyptian fields yield heavy oils of mixed-base
type. They contain only a small percentage of benzine, and
after topping this off the residue is an oil of high viscosity.
OCCURRENCE OF CRUDE OIL 67
The presence of paraffin wax gives the residue a high setting
point. Sulphur is contained in the crude oil to the extent
of 2 or 3 per cent.
In Australasia no oil-fields are as yet developed. Oil
has, however, been found in Taranaki, New Zealand.
In the island of Papua exploitation work is going on.
The foregoing is merely a very condensed summary of
the most important fields in active exploitation. Space
does not permit of reference to the numerous localities where
crude oil in small quantities has been obtained.
It will be seen from the foregoing that crude oils from
different sources exhibit a great diversity of character, both
as regards their physical constants and chemical constitution.
No scientific system of classification has as yet been evolved,
and this will not be possible until a great deal more is known
about the chemical constitution of their components.
The colour of crude oil ranges from practically colourless
in the case of the so-called white oils, which are naturally
filtered oils of rare occurrence, through shades of brown and
greenish brown or black of varying transparency, to the
deep black of asphaltic heavy oils such as those of Mexico.
The specific gravity varies from as low as 0760 in the case
of some of the very volatile oils of Rumania and Pennsyl-
vania, to nearly rooo in the case of some heavy Mexican oils.
The viscosity varies from that of oils as limpid as ordinary
kerosene to that of semi-solid asphalts.
The chemical properties show similar variation.
The carbon percentage ranges from 80 to 87, the hydrogen
from 9*6 to 14*5. The ratio carbon/hydrogen from 5*6 in
the case of the volatile oils of high paraffin content to 8'0 or
more in the case of heavy asphaltic oils.
The yield of commercial products also varies enormously,
lyight oils containing 50 per cent, or more of benzine are
known, and heavy oils containing no benzine or kerosene
fractions whatever. Great variation is often shown by the
crude oils from a particular field, so that without going
into very great detail no general summary, other than one
very rough, as given above, is possible.
68 PETROLEUM AND ALLIED INDUSTRIES
The world's output of crude oil for 1920, as contributed
by various countries, was as follows : —
United States. . . . 443,402,000 brls., i.e. 64-4 per cent.
Mexico . , . . 159,800,000 „ „ 23-2
Russia . . . . 30,000,000 „ „ 4-36
Dutch East Indies . . 16,000,000 ,,
Burmah . . . . 8,500,000 ,,
Rumania . . . . 7,406,318 ,,
Persia 6,604,734 „
Galicia. . . . . . 6,000,000 ,,
Peru . . . . . . 2,790,000 ,,
Japan (incl. Formosa) 2,213,083 ,,
Trinidad . . . . 1,628,637 ,,
Argentine . . . . 1,366,926
Egypt 1,089,213 „
France. . . . . . 700,000 ,,
Venezuela . . . . 500,000 ,,
Canada . . . . 220,000 „
Germany . . . . 215,340 ,,
Italy 38,000 ,,
688,474,251 „
The United States, Mexico, and Russia thus at present
produce over 90 per cent, of the world's output.
The estimated production for 1922 is 760,000,000
barrels.
GENERAL REFERENCES TO PART III., SECTION A.
Bacon and Hamor, " American Petroleum Industry," vol. i. McGraw-
Hill, New York.
Cadman, Sir John, " Oil Resources of the British Empire." J.R.S.A.,
July 30, 1920.
Emmons, " Geology of Petroleum." McGraw-Hill, New York.
Engler-Hofer, " Das Erdol," vols. I and 2. Hirzel, Leipzig.
Redwood, " Treatise on Petroleum," vol. I. Griffin.
" Monograph on Petroleum," Imperial Institute. J. Murray. 1921.
SECTION B.— DRILLING AND MINING
OPERATIONS
SEVERAL methods of drilling are employed in the petroleum
industry, the choice of the particular method in any one
case depending on various factors, such as the depth of the
well (500 feet in Ontario, 4000 or more in Galicia or Cali-
fornia), the nature of the strata to be penetrated, and the
amount of water present or available.
The methods employed may be classified into three
groups — •
(a) Abrasion or core drill methods.
(b) Percussion methods.
(c) Hydraulic rotary methods.
(a) Core drill methods, being slow and expensive,
are seldom used except for prospecting or test holes. In
hard formations a complete core of the material drilled through
can be obtained, and this may afford valuable geological
data, such as the dip of the strata, and fossils intact and
unbroken.
The tool used is a circular shoe or bit attached to the
end of a hollow tube wliich is rotated. The lower end of this
shoe may be either (i) set with diamonds, (2) cut into teeth
somewhat like a saw (calyx), or (3) plain, revolving on a
number of chilled shot, placed in the hole.
The diamond drill was first used in 1863. The calyx
method was developed in 1873, and the chilled shot method
later. By these methods cores up to 15 inches diameter
may be obtained. When using such drills a stream of
water is pumped down the hole to remove the abraded
material.
69
70 PETROLEUM AND ALLIED INDUSTRIES
(b) Percussion methods are, however, most generally
used.
Percussion methods may be classified into-1—
(1) Cable tool systems.
(2) Pole tool systems.
Various sub-divisions of these systems exist, differing from
each other in details only. For example, in the Canadian
system ash poles are used, in the Galician light rods of steel.
For any system of drilling a derrick is required, but those
used in the various systems differ considerably in detail,
being, however, similar in fundamental points. Space will
not permit of a detailed description of the various types.
For this, the reader must be referred to any of the standard
works on petroleum mining, such as that of Beeby Thompson.
The type of derrick used depends on the locality, on
the nature of the strata and the depth to which the well is
to be bored. Those used in the Ontario fields, where the
wells are only a few hundred feet in depth, often consist
merely of three poles fastened together at the top so as to
make a tripod.
For such shallow wells a portable drilling machine is often
employed. Derricks are often constructed of timber cut
locally, but where timber is scarce steel is often used.
The standard derrick which is largely employed is built
up of four legs braced together (Fig. 7). At the top is placed
the " crown block " (i), which carries the crown pulley, over
which the drilling cable passes. At the side of the derrick
far from the engine stand the " bull wheels " (2). These
consist of a drum on which the drilling cable is wound,
attached to a wrheel at either side. The wheel on one side
acts as a driving wheel, being grooved to receive the driving
belt, that on the other side is fitted with a steel band brake.
At the opposite side of the derrick is set the " samsou
post " (3), which carries the " walking beam "(4). One
end of the walking beam is connected by a rod called the
" pitman " (5) to the crank of the " jack " or " band
wheel " (6). This band wheel is driven by the engine and
DRILLING AND MINING OPERATIONS 71
transmits power to the bull wheels by means of a belt or
" bull rope." The other end of the walking beam supports
the drilling cable.
Just behind the band wheel the "sand reel" (7) is
placed. This is carried on a movable axis so that it can be
driven from the band wheel by a friction pulley. A light
FIG. 7. — A drilling rig.
cable passes from the sand reel over a light pulley at the
top of the derrick, and is used for raising and lowering
a sand pump for cleaning out the hole during drilling
operations.
Derricks used for deep- well drilling are often 140 feet
high, the great height allowing several lengths of casing
to be hauled up without disconnecting.
72 PETROLEUM AND ALLIED INDUSTRIES
The drilling engine is controlled by a " telegraph cord "
and reversing lever extending into the derrick. Steam is
supplied from a vertical boiler usually of about 20 to 40 h.p.
placed some little distance away.
The complete set of drilling tools is usually termed a
" string." It consists of the following : " rope socket,"
" sinker bar," " jars/' " auger stem," and " bit."
The rope socket is a device for attaching the drilling
cable to the tools ; the sinker bar is a long heavy steel bar,
which merely functions as a weight. It is often omitted,
but is sometimes placed
below the jars. The
jars are practically a
pair of interlocking
links. They have a
play or lost motion of
about 2 feet.
When the links of
the jars engage on the
upstroke a sudden jerk
is given to the bit
which loosens it, should
it tend to stick. When
drilling, the cable
should be adjusted so
that the upper link of
the jars does not de-
scend far enough to
strike the lower link. This can easily be adjusted by an
experienced driller by feeling the vibration transmitted
through the drilling cable.
The auger stem is a long cylindrical piece of steel. It
adds weight to the bit and helps to keep the hole straight.
Many types of bit are used according to the nature
of the rock through which the hole must be drilled. The
usual type is chisel shaped, the diameter of the cutting edge
being larger than that of the stem (Fig. 8).
Drilling tools are usually fitted with a conical screw
FIG. 8. — Types of drilling bits.
DRILLING AND MINING OPERATIONS 73
which fits into a corresponding socket on the lower end of
the auger stem. The jars, sinker bar, and drilling poles
(if used) are all so fitted. They are screwed together by
means of a very powerful wrench or jack operated on the
derrick floor.
The first stage in the actual drilling of a well is the
insertion of the " conductor." This is usually an ordinary
steel drive-pipe, 10 to 30 feet long.
This must be very carefully fixed in a
vertical position as it serves to guide
the first lengths of casing fixed into
the well.
Owing to the length ofc a complete
string of tools, drilling cannot be
started in the normal manner used
when the hole is deeper. The method
termed " spudding " is therefore
adopted. A bit and auger stem are
connected to the cable and lowered
into the hole till they touch bottom,
and the cable is fixed. A " spudding
shoe " is then fixed on to the cable
near the bull wheel and connected
by a " jerking " rope to
the crank of the band
wheel.
As the crank re-
volves, the bull wheels
being fixed, the cable is
drawn forward and then
released, an up - and -
down motion thus being transmitted to the tools (Fig. 9).
As the hole is bored detritus rapidly accumulates and
must be removed from time to time. This is effected by
raising the tools from the well and lowering the " sand pump "
or " baler." This consists merely of a length of tubing with a
valve at the bottom opening inwards, which is operated by
a projecting stem. As this stem strikes the bottom of the
FIG. Q. — Arrangement for spudding.
74 PETROLEUM AND ALLIED INDUSTRIES
hole the valve opens allowing the muddy debris to enter.
As soon as the sand pump is raised from off the bottom of
the well the valve naturally closes again, retaining the
contents, which are discharged into a drain at the top of
the well by means of lowering the sand pump on to the
ground, the valve being thereby opened. The hole is
usually drilled by spudding in this way to a depth of about
150 feet or so. The string of tools is then attached to the
" walking beam " by means of the " temper screw," an
arrangement whereby the cable can be let out a few inches
at a time as drilling proceeds.
Drilling is then carried on by means of the walking
beam, a manilla cable being often used. For great depths,
however, this is usually replaced by a steel cable.
In the case of hard strata the walls of the well require
no protection, but when the strata are soft or yielding
the well must be lined with " casing " in order to prevent
the caving in of the well. lycngths of casing or drive-pipe
are lowered or forced down into the well following the
drill, the lengths of pipe being screwed together. As an
indefinite length cannot be sunk owing to friction it is usual
to start the well with a tool of large diameter, and to
insert large diameter drive-pipe or casing, driving this to as
great a depth as the friction will allow.
The initial diameter of the well depends on the depth
to which it is to be drilled and on the nature of the strata.
Casing up to diameters of 14 inches or even more is in
general use, but in Russia pipes of larger diameter, con-
structed of plates riveted together, are often used. Casings
of several different types are used dependent on local
conditions.
The lower end of the string of casing is usually armed
with a " casing shoe," a ring with a sharp edge. The casing
can be " set " by driving this into any suitable stratum
when the casing cannot well be driven to a greater depth.
To enable the casing to sink in the well " under-reaming "
is often necessary. This is carried out by a special under-
reamer, which is a tool with an expansible bit, so that the
DRILLING AND MINING OPERATIONS 75
cutting edges of the bit can be squeezed together to allow
of its passage through the casing. When it reaches a point
below the casing the cutting edges are forced apart by
means of powerful springs, so that a hole of larger diameter
than the casing can be bored.
Casing performs a further and very important function
in the shutting off of water.
Water-bearing levels are often encountered in boring
a well. If these are not adequately sealed up or shut
off, water will descend, perhaps even behind the casing,
to lower levels and may enter the oil-producing layer, thus
spoiling not only that particular well but probably others in
the same stratum. The adequate shutting off of water
is thus of the greatest importance. In many countries
this is recognized, and regulations are in force to ensure
that this is properly carried out.
The process most generally used is that of " cementing."
The lower edge of the outside string of casing is set in
position, usually in an impervious layer. Cement is then
forced down to this point, between the outer and inner
casing ; or the inner casing may be cut off just above this
point and the space between the two filled by cement, the
well being plugged at this point temporarily to allow of
this being done. A description of the methods of shutting
off of water from oil wells is outside the scope of this work.
Detailed descriptions may be found in such works as Beeby
Thompson's " Oil Fields of Russia " and in the various
bulletins published by the U.S.A. Bureau of Mines on this
subject.
When a string of casing has been set, drilling is con-
tinued with a bit of smaller diameter, this being followed
up by a string of casing of smaller diameter, which of course
must extend to the top of the well. This second string of
casing is forced down as far as possible and eventually set,
the drilling being then continued with another bit of still
smaller diameter.
A finished well may thus have a diameter of 16 inches
or more at the top and 4 inches at the bottom, and may have
76 PETROLEUM AND ALLIED INDUSTRIES
several strings of casing extending to successively greater
depths, arranged one inside the other in telescope fashion
(Fig. 10).
It is not, however, necessary that each string of casing
should extend to the surface after the well has been com-
pleted and found to be successful. The upper or free
portions of the inner strings may be cut off by a special
tool lowered into the well, and removed, the points at which
one string of casing is set and
the next smaller size starts
being well sealed up by
cementing.
In drilling wells many diffi-
culties are usually encoun-
tered, and many ingenious
devices are adopted for over-
coming these difficulties.
Boulders are sometimes
encountered in a clay, and if
large may easily be mistaken
for a bed of hard rock. These
are usually broken to pieces
and removed sometimes by the
aid of explosives. When drill-
ing through highly inclined
strata there is often a tendency
for the drill to deflect to one
side especially when a hard
FIG. ro. — Strings of casing in
a well.
stratum is encountered, tending to follow the dip of the strata
and so causing the hole to diverge from the vertical. This can
be avoided by slow and careful drilling with a long auger stem.
Dry sands also cause trouble, as they absorb water, so
that very large quantities would need to be pumped into the
hole. If drilling were attempted without water the bits
would overheat and the sand would impede the action of
the drill. In such a case mud is pumped into the hole.
This fills up the pores of the sand by a puddling action and
allows drilling to proceed.
DRILLING AND MINING OPERATIONS 77
" Spalls " of rock or loose stones may fall from the
sides on top of the bit and jam it so that it cannot be moved.
These may then require drilling out by a smaller bit, to
render the large bit free again.
Soft muds and clays are difficult to deal with as they fill
up the hole as soon as it is formed. In such cases drilling
must be quickly carried out and the casing must closely
follow the bit. Cavities are sometimes found, particularly
in limestone strata.
Quicksand is sometimes encountered, and if the hydro-
static pressure is great this may quickly flow into the hole
so as to engulf the tools, making their withdrawal very diffi-
cult. A quicksand can, however, usually be driven through
by keeping a good head of water in the well, so as to overcome
the hydrostatic head of the sand. In some cases cement
may be introduced into the well so as to percolate into the
sand and form a solid block which may be subsequently
drilled through. An ingenious method of drilling through
quicksand was devised by Poelsch in 1883. He drove
pipes into the quicksand and circulated cold brine through
them, thus freezing the sand into a solid mass through which
boring could be conducted in the usual way. The need
for such methods, however, very rarely arises.
A variation of the percussion system of drilling as described
above is the Water flush method. The cable is replaced
by a string of pipes screwed together, through which water
can be pumped, emerging through two holes in the upper
part of the bit. The stream of water carries up the debris
to the surface, thus obviating the need for sand pumping.
(c) The Hydraulic rotary method, which was first
used in the famous Spindle Top field of Texas, has now
come into general use, especially in cases where soft
materials are to be penetrated.
The plant consists of a heavy revolving table driven
by cog gear and a chain and sprocket wheel. The drill
pipe passes through the centre of the table, being gripped by
clamps which, however, are arranged so as to allow the
piping to be gradually lowered. The drill pipe is usually
78 PETROLEUM AND ALLIED INDUSTRIES
made of heavy 4-inch piping and carries a fish-tail drill
FIG. ii. — Arrangement for drilling by rotary method.
at its lower end. Water is supplied to the upper projecting
end of the pipe by a flexible hose and swivel joint. As the
DRILLING AND MINING OPERATIONS 79
drill is rotated water is continuously pumped down the
pipes, and emerges through holes in the bit, carrying the
detritus upwards through the hole. The detritus is allowed
to settle out of the water, and this can then be used again.
In fact, muddy water is often used in order to clog up the
pores of any sand which is being penetrated so as to avoid
loss of water. In drilling through clay, however, clear water
is used. The well often requires no casing, as the mud
puddles its sides so that the material is able to stand up
alone.
In this system of drilling it is essential that the operation
be continuous. If it be stopped then the accumulation of mud
will jam up the bit and drill pipes. A recent improvement
is the Sharp-Hughes patent cone bit. This consists of two
hard steel-toothed cones which can revolve on bearings
supplied with lubricating oil by a special pipe fitted inside
the drill tube. The use of this bit enables the rotary outfit
to be used for drilling through hard rock also.
The hydraulic rotary can penetrate soft strata at a
great speed. In Texas wells have been drilled at the rate
of 30 feet an hour.
The fact that the mud puddles up the sand is a disad-
vantage in drilling in an area the underground geology of
which is not known, as it is possible to pass through an oil
sand without noticing it, if the hydraulic pressure of the
water column in the well is greater than that of the oil in
the sand.
Fishing. — In spite of all precautions tools occasionally
become detached ; a cable may break, tools may become
unscrewed, or the screw pins may break. The difficulties
of extracting such lost tools, " fishing " as this is called, are
great.
In the first case some information must be obtained
as to the position of the tools in the hole. This is often
obtained by lowering down a special tool with a bell-shaped
opening filled with wax. An impression of the top of the
lost tools may be so obtained and a special fishing tool may
then be designed to catch hold of them. Many ingenious
80 PETROLEUM AND ALLIED INDUSTRIES
tools and methods have been designed and even special photo-
graphic apparatus has sometimes been lowered into a well.
Several standard types of fishing tools such as the
" slip socket " and " cable spear " are often used. The
slip socket consists of a tube containing two movable slips,
one on either side, with teeth pointing
upward. The apparatus is lowered
over the lost tools, and on raising it
the toothed slips, falling as low as
they can in the bevelled grooves in
which they slide, bite into the tool
and hold it firmly while it is pulled up
(Fig. 12). The cable spear is simply
a "spike" with barbs pointing up-
wards so as to engage in the cable
which may have broken and slipped
down into the well.
Further trouble may be encoun-
tered by casing slipping into the well,
or becoming distorted. For details of
methods of dealing with these various
difficulties reference must be made to
one of the standard works on drilling.
They fall outside the scope of this
book.
Flowing Wells. — When the drill-
ing has been completed and the oil
sand reached, the well may gush, or
quietly flow, or need pumping, accord-
ing to the gas pressure.
In Russia, California, and Mexico " gushers " of enormous
size, yielding 10,000 tons or more per day, have often been
struck. Such large wells frequently get out of control,
a large part of the oil may be lost and much damage to
surrounding property may ensue.
The greatest oil well so far brought in was the Potrero
del L,lano No. 4 of Mexico, which produced at one period at
the rate of 25,000 tons per day.
FIG. 12. — Slip socket.
DRILLING AND MINING OPERATIONS Si
Many wells, under control, flow for years at a continually
decreasing rate owing to the gradual fall in gas pressure.
In the case of flowing wells the oil is led by pipes connected
to the casing-head, through a gas separator, if necessary,
to storage tanks.
Methods of Raising Oil. — Many wells, however, do not
flow but require pumping.
This is usually effected :
(a) by means of mechanically operated pumps,
(b) by means of an airlift system, or
(c) by baling.
(a) The pump consists of a working barrel to the lower
edge of which is attached the suction pipe, on the upper end
of which is the suction valve. The piston or plunger of the
pump is fitted with several cup-leathers, which expand
against the walls of the barrel forming a tight piston. This
is necessary, as such a long column of oil requires lifting.
The plunger is operated by means of a cable or steel rods
attached to the walking beam.
In many fields where the wells are close together a number
of wells are pumped from a central station. An oscillating
wheel or " jerker " has attached to it a number of steel rods
or cables which operate the pumping jacks at the various
wells. In this way pumping is economically carried out, as
the wells can be so connected up that half the pump rods
are descending while half are ascending. In the Petrolia
field of Canada many such wells may be operated by a
12-h.p. engine.
(b) In some fields the airlift system is used. The opera-
tion of this system depends on the aeration of the column of
oil in the well by means of a jet of compressed air emitted
from the bottom of a central tube lowered to the bottom of
the well. The pressure due to the aerated column of liquid
must of course be less than the pressure due to the previously
existing column of liquid in order to obtain a flow (Stirling,
"The Airlift System of Raising Oil," J.I.P.T., 1920, p.
379)-
The chief advantages of this system are —
P. 6
82 PETROLEUM AND ALLIED INDUSTRIES
1. Automatic action and reliability.
2. No moving parts to get out of order.
3. Applicability to oils containing sand in suspension.
4. Applicability to wells of small diameter and to
crooked boreholes.
5. lyow operating costs.
6. Concentration of machinery in one building and
transmission of compressed air with little or no loss.
In cases where the airlift system cannot be used, and where
owing to the sand content of the oil ordinary pumping
methods are inapplicable, resort must be had to baling. This
method is largely used in Russia and Rumania. The baler
consists merely of a long tube with a valve at the bottom,
a sand pump, in fact, which is alternately lowered into
and raised from the well. Such a method of operation is,
of course, the most expensive.
Another method, somewhat similar in principle, is that
known as swabbing. A string of tubes fitted with an
expanding packer is lowered into the well, the packer being
fixed some 20 feet or more from the lower end of the
tubes. The arrangement is then hauled up, a valve in the
tubing automatically closing. The tubes and packer thus
act as a piston and exert a great suction on the oil. This
process is of great use also for cleaning out a well which may
have become clogged with waxy deposit or sand.
Shooting. — In order to increase the yield of an oil well
the method of " shooting " is often employed. A charge
of many quarts of nitro-glycerine is lowered in a canister
into the well, and exploded by means of a time fuse. The
powerful explosion at the bottom of the well shatters the
rock in the vicinity, with the result that a series of cracks
radiating from the well enable the oil to flow thereto more
easily, the daily yield being thereby often considerably
increased.
A method of mining for oil by means of shafts and
galleries has been applied in the fields of Pechelbronn,
Alsace, by which it is maintained that a greater yield of oil
can be obtained than by boring methods (Paul de Chambrier,
DRILLING AND MINING OPERATIONS 83
J.I.P.T., 1921, p. 178). The method in this particular
area has proved of value, but its application would appear
to be limited, especially in the case of fields where the oil is
found at great depths and which yield oil of high volatility.
Moreover, in many fields where the anticline or dome
structure predominates and where water underlies the oil,
the upward percolation of the water consequent on the
gradual removal of the oil must remove from the oil sands
most of the oil which they would otherwise retain.
Oil Well Fires. — Oil and gas wells occasionally catch
fire, owing to lightning, frictional electric sparks, or careless-
ness. Various ingenious methods for extinguishing such
fires have been devised. In some cases they have been
choked out by steam, in others by the use of a foam caused
by the interaction of two aqueous solutions liberating
carbon dioxide An ingenious method of extinguishing a
gas- well fire was recently described in the Oil Trade Journal,
April, 1920. A package of dynamite was drawn on a
suspended cable until it was in the close vicinity of the
flame, and was then exploded, the explosion wave literally
blowing out the flame.
Oil-field Waste. — Oil-field operations are unfortunately
often associated with great waste, both of material and
labour. This subject has recently been dealt with in a
paper read by A. Beeby Thompson before the Institution
of Petroleum Technologists on November 8, 1921. Oil-field
waste may be divided into : (a) Development waste. Owing
to the mobility of petroleum a well put down on one lease
may draw supplies partly from an adjacent lease. As a
result of this an unnecessary number of wells are put down
(often too hurriedly) along the boundary line between ad-
jacent leases, especially when the leases are of small area.
(b) Extraction losses. The occasionally bringing in of
uncontrollable wells results in much loss of both valuable
oil and gas. Moreover, even with the most improved methods
of extraction, a large proportion of the oil contained in a
porous bed necessarily remains underground.
(c) Fuel Waste. Owing partly to the flexibility and
84 PETROLEUM AND ALLIED INDUSTRIES
fool-proofness of the steam engine, this is still the favourite
source of power, often in spite of the fact that enormous
supplies of gas are running to waste. Owing to fire risks
the boilers (which are usually of low efficiency) are placed
some considerable distance from the derrick, so that the
losses in transmission of steam (often through unlagged
lines) is very considerable.
(d) Evaporation losses. The importance of this is too
seldom recognized. It has been calculated that (Wiggins,
Pet. Age, 1920) the losses by evaporation in the Mid-Continent
fields of America amounted to nearly 3 per cent, of the total
gasoline output of the United States. Even in well-designed
storage tanks the loss by evaporation of a benzine may
amount to several percents. per annum. This subject is now
receiving serious attention, insulated tanks have been tried
and systems of vapour absorption are being introduced.
GENERAL REFERENCES TO PART III., SECTION B.
Arnold and Garfias, " The Cementing Process of excluding Water from
Wells." Technical Paper 32, U.S. Bureau of Mines.
C. H. Beal, " The Decline and Ultimate Production of Oil Wells."
Bulletin 177, U.S. Bureau of Mines. Petroleum Technology 51.
Beeby Thompson, " Petroleum Mining." Crosby Lockwood.
F. G. Clapp, " Petroleum and Natural Gas Resources of Canada,"
vol. 2. Canada Department of Mines.
W. H. Jeffery, "Deep Well Drilling." W. H. Jeffery Co., Toledo,
Ohio.
Ockenden and Carter, " Rotary System of Drilling Oil Wells."
J.I.P.T., vol. 6, p. 249.
Ockenden and Carter. " Plant used in the Percussion System of Drilling
Oil Wells." J.I.P.T., vol. 5, p. 161.
SECTION C.— STORAGE AND TRANSPORT OF
CRUDE OIL AND ITS LIQUID PRODUCTS
THE conditions of storage of crude oil on the fields often
leave much to be desired. Particularly in the case of
opening up of new fields, when the probable output is a
matter of conjecture only, adequate storage facilities have
often not been provided, and much oil has in consequence
been wasted. Occasionally exceptionally large gushers are
brought in and may get out of control, so that hastily
constructed earthen reservoirs are perforce used for
temporary storage, the loss by leakage and evaporation in
such cases being very great, especially in the case of light
and volatile crudes.
The practice of storing oil in open reservoirs, at one
time common, when the volatile fractions were a drug in.
the market, is happily now rare and need not, therefore, be
described.
In Canada and Galicia underground storage tanks are
extensively used. They are constructed by excavating
circular holes, lining the sides with wooden planks and
puddling behind these with clay. Wooden roofs covered
with asphalt roofing-felt are used.
Wooden cylindrical tanks made of staves, hooped to-
gether with steel bands, are still largely used in America.
Such tanks are, however, always of small capacity, and are
used merely as receiving tanks at the well mouth.
The use of steel storage tanks is, however, now almost
universal. Such tanks are constructed of various capacities
up to 55,000 barrels, i.e. 8000 tons, sometimes larger. Such
tanks may have diameters up to 100 feet or more and usually
range in height up to about 36 feet.
85
86 PETROLEUM AND ALLIED INDUSTRIES
They are constructed of steel plates riveted together,
the thickness of the plates diminishing towards the top
of the tank. The lowest course of plates is riveted to the
bottom by means of a heavy angle iron. The roofs are
usually of the self-supporting type, consisting of thin sheet
plates supported on the rafters and purlins. Wooden roofs
are sometimes used, but this is inadvisable, particularly in
areas where thunder-storms are frequent. Good metallic
contact of the roof plates with the side is of great importance,
otherwise electric disturbances may cause sparking and the
loss of the contents of the tank by fire.
Tanks designed for the storage of volatile crudes or
distillates should always be made gas-tight, and fitted with
some form of pressure and vacuum valve (7, Fig. 13).
FIG. 13. — Diagrammatic view of steel tank for storage of oil.
The tank must be fitted with : a water draw-off valve (i)
at the bottom, which can be closed by an internal valve ;
one or more inlet and outlet pipes situated near the bottom
of the tank, and provided either with internal valves (2) or
with a swing pipe arrangement (3).
These internal valves or swing pipes are a necessary
STORAGE AND TRANSPORT OF CRUDE OIL 87
-L
88 PETROLEUM AND ALLIED INDUSTRIES
precaution against the breaking of the external valves and
consequent loss of oil.
Tanks are further provided with one or more man-
holes (4, Fig. ISA), on the bottom course of the plates and
on the roof, to allow of entry for cleaning purposes, with
one or two " dipping holes " (5) in the roof fitted with plugs
for gauging purposes.
Some form of water sprinkling arrangement (6) is also
usual, for cooling the roof and sides of the tank in hot
weather, or in the event of an adjacent tank being on
fire.
The loss by evaporation of volatile fractions is a very
serious question, which has in the past received far too little
attention.
Recent tests carried out in the United States (J. H.
Wiggins, Petroleum Age, July, 1920) have shown that the
losses, owing to filling tanks in the summer by overshot
connections, may amount to i to 2\ per cent, a day.
Light crude oil containing 30 per cent, of benzine was
found to lose 3 per cent, of its volume in being stored in a
well-made steel tank for a year. As the most volatile
fractions are lost, the monetary loss amounts to much more
than 3 per cent.
With well-made tanks, fitted with gas-tight roofs, in
the tropics, the losses can be reduced to about 3 per cent,
per annum, but nevertheless usually exceed this figure even
in temperate climates.
The chief causes of loss in storage are : —
(1) Leakage through faulty seams ;
(2) Expulsion of air and benzine vapour when pumping
into a tank ;
(3) The alternate expulsion of a mixture of air and
benzine vapour during the day and the sucking in of air
during the night, the so-called " breathing " of a tank.
Leakage can be minimized by careful construction. The
use of welded tanks will doubtless become common in the
future, a few having already been constructed.
Evaporation losses due to pumping and breathing cannot
STORAGE AND TRANSPORT OF CRUDE OIL 89
be entirely avoided, but may be minimized in several
ways.
The storage tanks should always be painted white.
Some experiments conducted in Mexico showed that a loss
of 0'59 per cent, per annum for a tank painted black, could
be reduced to 0*28 per cent, by merely painting it white.
Storage losses may also be considerably reduced by
connecting tanks by means of vapour lines to a scrubbing-
tower, down which heavy distillate or gas oil is trickling.
Vapours will thus be largely absorbed and may be recovered
by distillation of the gas oil. Such installations are, how-
ever, as yet very rare.
Crude oil after collection at a central tank farm is
transported to the refineries by pipe-line, tank car, or tank
steamer.
The pipe- line system of the United States is now very
extensive, about 45,000 miles of transport pipe-lines now
being in use.
Many other pipe-lines of considerable length, e.g. those
from the fields of Rumania to Constanza, and that from
Baku to Batoum, have also been laid down.
These pipe-lines, which are usually of diameters of from
4 to 12 inches, are laid underground. Pumping stations are
set up at intervals along the line, the distances between the
pumping stations being determined by the viscosity of the
oil to be pumped. Pressures up to 800 or 900 Ibs. per
square inch are often employed. In the case of very viscous
oils, heating arrangements are usually installed at the
pumping stations.
A list of the principal pipe-lines in the United States is
given in Bulletin No. 14 of the Kansas City Testing
laboratory.
The rate of flow of liquid moving through a pipe-line
depends on various factors : the pressure at which the
liquid is fed in by the pumps, the viscosity of the oil, and
the diameter, length, nature of internal surface, and number
and nature of bends of the pipe-line.
A discussion of this subject is to be found in the J./.P.T.,
90 PETROLEUM AND ALLIED INDUSTRIES
vol. 2, p. 45, Glazebrook, Higgins, and Pannel, and tables
for calculating the flow of oil in pipes are given by Preston
in Chemical and Metallurgical Engineering, 1920, pp. 607,
685.
Railway tank cars are also largely used for the transport
of crude oil and liquid petroleum products. Tank cars
supplied with steam coils, which can be connected up to a
steam line, at the discharging stations, are used for the
transport of heavy lubricating oils and even asphalts which
are solid at ordinary temperatures.
The design of such cars depends to a large extent on the
conditions laid down by the railway companies over whose
lines the cars must run. Cars designed to carry benzines
or other inflammable products are usually not permitted to
have any connections to the bottoms of the tanks, but must
be pumped out by means of the manhole or connections on
the expansion dome on the top of the car.
Transport by sea is effected by means of specially
designed tank steamers, which are sometimes fitted with
steam-heating coils to facilitate the discharge of heavy
viscous fuel oils. In the majority of tank steamers the
engines are usually fitted aft, in order to avoid the necessity
for constructing an oil-tight shaft tunnel which must pass
through the oil tanks, if the engines were placed midships.
The engine space aft, and the stores, and crew's accommoda-
tion forward, are separated off from the oil tanks by means
of " coffer-dams." These are made of two water-tight steel
transverse bulkheads, a few feet apart, the space between
these forming tanks which are filled with water. The oil
tanks are thus isolated fore and aft from the rest of the ship
by means of two solid walls of water. The ship is usually
divided into a number of tanks by transverse bulkheads,
and each tank is divided into a port and starboard portion
by means of a longitudinal bulkhead. In order to avoid
" slack tanks," i.e. tanks partly filled, and to allow for the
expansion and contraction of the oil owing to changes of
temperature, there are fitted on to the top of the tanks
" expansion trunks " of relatively small cross section. These
STORAGE AND TRANSPORT OF CRUDE OIL 91
expansion trunks further allow of more accurate gauging of
the quantity of oil in the tanks. Further, in order that the
full carrying capacity of the ship may be utilized when
carrying oils of low specific gravity, several smaller tanks on
iwiiin
top of the main tanks, termed " summer tanks " are usually
fitted. The arrangement of the tanks will be readily under-
stood from an inspection of the diagram (Fig. 14).
The ship is fitted with one or more pump-rooms in
92 PETROLEUM AND ALLIED INDUSTRIES
which the discharge pumps are situated as low down as
possible. One or more suction lines extend through the
tanks, and are fitted with valves operated by spindles
extending to the upper deck. The discharge line is con-
nected to the line on the wharf by means of flexible hoses or
a jointed steel swing pipe. Modern tank steamers are
built up to capacities of 15,000 tons and can discharge this
oil at the rate of as much as 400 tons per hour.
The total tanker tonnage of the world now amounts to
over 3,500,000 tons. This large fleet consists of 709 steam
or motor driven vessels and 124 sailing ships, and a further
250 or thereabouts are under construction.
The evolution of the modern tank steamer has been well
described by II. Barringer in the J.I.P.T., vol. i, 1915,
p. 280.
REFERENCES TO PART III., SECTION C.
Barringer, " Oil Storage," J.I.P.T., vol. 2, 1916, p. 122.
Engler-Hofer, " Das Erdol," vol. 5. Hirzel, Leipzig.
Pogue, "Economics of Petroleum." J. Wiley & Sons, New York.
SECTION P.— THE DEHYDRATION OF CRUDE
OILS ON THE FIELDS
CRUDE oil as it issues from the well is often mixed with
water, which is often saline, the water being emulsified in
the oil. As the transport of such water-containing oil by
pipe-line or tank steamer really involves freight charges on
the contained water, steps are taken to dehydrate such oils
on the fields as far as possible before transport to the
refineries. This dehydration may often be more or less
completely effected, especially in the case of crudes of low
specific gravity, by merely standing in storage tanks. In
such cases most of the water settles out, sometimes clear,
but often in the form of a thick emulsion (known as B.S. or
" bottom settlings ") which can be drawn off. This emulsion
still contains considerable proportions of oil, and may be
separately treated by one of the methods described below.
Many heavy crudes do not, however, readily separate out
the water, some in fact retain it obstinately. Such must be
subjected to special treatment, as apart from the question
of unnecessary transport of water, the distillation of emulsified
oil presents difficulties.
Several methods for treating such heavy emulsions or
watery crude oils have been devised.
(a) Methods depending on the action of electrolytes,
e.g. dilute acids, or solutions of metallic salts, have been
suggested and occasionally employed. Such methods have,
however, met with little success.
(b) Centrifugal Methods. — The separation of emulsified
oil is usually effected in the laboratory by an ordinary hand-
driven centrifugal apparatus, the action being accelerated
by the dilution of the oil with benzine. Such a method
93
94 PETROLEUM AND ALLIED INDUSTRIES
would, however, be generally too costly in practice, as the
benzine would need to be separated off again by distillation.
The centrifugal principle has recently been employed with
success in the Sharpies super-centrifugal apparatus, which
is now in operation in many fields for the treatment of
crudes containing water in suspension.
The -centrifugal machine employed operates at a speed
of 17,000 revolutions per
minute, exerting a sepa-
rating force nearly 17,000
times that of gravity.
The machine consists of
a rotor, a cylindrical
vessel 36 inches long and
4 1 inches diameter, sus-
pended in a vertical
position from a spindle
rotating in a ball bearing.
The rotor or bowl (Fig.
15) is a plain cylindrical
tube provided with an
inlet port at the lower end
and outlet ports at the
upper end, through the
outer of which water runs
off, and through the inner,
oil. The machine thus
functions as a separating
tank acting under an enor-
FIG. 15.— Sharpies super-centrifugal mOusly increased gravita-
machme. J
tional force.
The oil to be dehydrated is fed in at the bottom and
under the influence of the centrifugal force separates into
two layers, the outer (G) being water with little or no oil,
the inner (H) being oil with little or no water. The water
flows off through the lower port (J), the oil through the
inner port (D), these being collected separately in the
receivers K and I
DEHYDRATION OF CRUDE OILS ON FIELDS 95
The rate of flow through the apparatus is controlled by
the rate of feed, this being adjusted so as to permit the oil
to remain in the apparatus sufficiently long to allow of
separation of the water taking place.
The capacity of a machine of the dimensions given above
will naturally depend on the nature of the emulsion under
treatment, but it may be taken that an emulsion containing
8 per cent, of water could be handled at the rate of about
ij tons per hour. The apparatus can also be used to effect
a separation of oil from the sludge which settles out on the
bottoms of storage tanks, a product which is otherwise
difficult to handle (U.S. Pat. No. 1232104).
(c) Electric Methods. — It has been found that crude
oil emulsions readily separate out into their constituents
when placed in a strong static electric field. This principle
has been employed in various processes which are now in
common use for treating watery crudes.
A usual type of plant consists of a tank, eight or nine
feet diameter and about double that in height, fitted with
water draw-off and heating coils. The body of the tank is
filled with a series of flat parallel plates, alternate members
of which are earthed to the tank, the others being connected
up to a transformer which supplies single phase alternating
current at 11,000 volts.
The emulsified crude oil is pumped in near the bottom
of the tank, the water separates out and is drawn off, and
the emulsion-free oil passes off from the top. In another
well-known type of plant (the Cottrell) one electrode consists
of a central revolving cage built up of a central axis carrying
metallic discs, the other electrode being the outer wall of the
cylindrical tank. The actual way in which the separation
of the emulsion in such plants takes place is not fully under-
stood.
Oil containing 85 per cent, of water has been in this way
successfully treated. The cost of operation is very low and
the plant requires very little attention. (Electrical Review,
New York, October 25, 1919.)
(d) Heating under Pressure.— Most crude oil emulsions
96 PETROLEUM AND ALLIED INDUSTRIES
may be separated effectively by heating under pressure.
Pressure is necessary as the splitting point is usually above
the boiling point of water at ordinary pressure. This
method, which works well in the laboratory, has not, however,
so far been applied in practice.
(e) Distillation Methods. — The distillation of wet crude
oil in ordinary stills presents technical difficulties owing to
the liability to boil over or " puke." This difficulty is got
over by distillation in tubular retorts, the foaming mass of
hot oil, steam, and vapours being allowed to pass into a
large vessel, a separating box, whence the steam and vapours
pass off to condensers, the dehydrated crude running out
from the bottom through heat exchangers to storage. Such
dehydrating plants are now common, and are often used to
distil off some of the volatile fractions from a crude oil as
well as the water. They are consequently often termed
" topping " or " skimming " plants. They are described in
detail under distillation plant (vide Part VII., Sect. A), to
which the reader is referred.
GENERAL REFERENCES TO PART III., SECTION D.
Sherrick, "Oil Field Emulsions." /. Ind. and En°. Chem., Feb. 1920.
Thomas, "Review of the Literature of Emulsions," /. Ind. and Eng.
Chem., Feb. 1920.
PART IV.— CRUDE OILS PRODUCED BY
THE DISTILLATION OF SHALES,
COALS, LIGNITES, AND THE LIKE
SECTION A.— CHARACTERS AND DISTRIBU-
TION OF OIL SHALE
THE shale oil and petroleum industries, though of about
the same age, have developed to very different extents,
the former being at the present tune of relatively little
importance. Shale oils have so far always been in the
unfortunate position of having to face the competition of
the more cheaply manufactured products of petroleum,
in consequence of which the shale-oil industry has had a
somewhat checkered career. It owes its continued existence
indeed largely to the fact that ammonium sulphate is
produced as a by-product.
There can be no doubt, however, that a great future
is in store for this industry, the development of which will
become of increasingly greater importance as the demand for
petroleum products increases. Immense though the
potentialities of petroleum production are, the end of
many important oil-fields is in sight. In the United States,
for example, where enormous deposits of oil shale exist,
the importance of the development of this industry is fully
realized and active efforts are being made to establish it
on a firm basis.
Oil shales as distinct from oil sands do not normally
contain oil as such, as they yield up little or no portion of
their organic content to solvents. The oil obtained from
oil shales is produced as a result of the chemical changes
brought about by the action of heat. Oil sands, on the
contrary, readily yield up their bituminous material to such
p. 97 7
g8 PETROLEUM AND ALLIED INDUSTRIES
solvents as carbon disulphide. There are, however, certain
types of shale which do yield an appreciable content of
soluble material. J. Gavin, in a report recently issued
by the U.S. Bureau of Mines, entitled " The Solubility of
Oil Shales in Solvents for Petroleum," has investigated this
subject. He finds that in the case of a Colorado shale
2*04 per cent, in carbon tetrachloride, 1*85 per cent, in
carbon bisulphide, 133 per cent, in acetone, 2*23 per cent,
in benzol, and 2*41 per cent, in chloroform, these figures
representing from 10 to 18 per cent, of the yield of oil obtain-
able by distillation. He points out, however, that the
extracted material is not oil, in the common sense of the
word, but resembles certain of the natural products which
are supposed to have resulted from oxidation of petroleum.
He also points out that the solubility of an oil shale is not
an index of its relative oil yield.
Oil shales are often termed bituminous shales, just as
types of coal are described as bituminous. The author
does not like the use of the term " bituminous " in this
connection as the shales really contain no bitumen as such.
Pyrobituminous shales is a more accurate term ; however,
to avoid any misunderstanding the term " oil shale " may be
used. A shale saturated with petroleum would be termed
a "petroliferous" shale.
Oil shales are thus composed of two classes of constituents,
the inorganic material which remains as ash after distillation,
and the organic material, the thermal decomposition of
which gives rise to the crude oil. The organic material of
shales is usually designated by the term " kerogen."
Oil shales show great variation in properties, not only
of the inorganic, but also of the organic components. In
general they are stratified rocks composed largely of
argillaceous, though sometimes of calcareous material.
They are usually dark in colour, but sometimes brownish
or even yellowish, sometimes hard and brittle, but often
tough and capable of being cut with a knife. They occur
in beds ranging from a few inches in thickness to many feet.
In many cases the total thickness of the shale beds in one
CHARACTERS OF OIL SHALES 99
shale-bearing formation amounts to many hundreds of
feet.
The inorganic portion of a shale may be considered merely
as a carrier for the organic material. The organic portion,
the so-called " kerogen," shows great differences of character
in different shales.
This great variation in character is illustrated by the
following ultimate analyses of the organic part of various
shales from different sources : —
1 .. .v. 76-9 8'8 4-4 27 7*i
2 . . . . 70-8 9-6 14-5 2*3 2*8
3 .. .. 69-6 8'i 20*3 0-2 1-8
4 . . . . 68*4 8'6 4*9 0*9 17-2
5 •• •- 66'8 9*3 J77 * '& 4*4
6 .. .. 64-1 6*8 23*6 2*i 3*4
7 .. .. 58-6 8*0 22*4 i'i 9*9
The ratio carbon/hydrogen varies from 7*2 to 9*4. The
extreme variations in oxygen and sulphur content are very
noticeable. The above analyses were made on individual
shales from various countries. Individual samples from
various seams in the same area even display considerable
variation in character.
Considerable attention has been given by Cunningham-
Craig to the microscopic study of oil shales, torbanites, and
cannel coals (J.I.P.T., vol. 2, p. 238). He points out that a
distinct substance varying in colour from a pale yellow to a
deep reddish-brown as viewed in a microscopic section, is
characteristic of all oil shales and cannel coals. This peculiar
yellow body shows no definite structure, and under the
microscope shows irregular shapes often completely
imbedding portions of the mineral matter. As a result
of a considerable amount of microscopic research, Craig
has come to the conclusion that in the case of boghead
coals, or torbanites, this " kerogen " has developed in
situ, but that in oil shales it may have been largely introduced
from some outside source.
ioo PETROLEUM AND ALLIED INDUSTRIES
Of the chemical nature of this " kerogen " little definite
is at present known, but there is evidence which points to
its being derived, at least in the case of certain oil shales,
from crude petroleum. It has not yet been isolated, as it
is practically insoluble in any of the known solvents. In
this respect it bears some resemblance to the naturally
occurring kerites (usually termed "asphaltites"), wurzilite,
and albertite. This resemblance is further borne out by
the fact that the carbon/hydrogen ratio is of the same order,
7 to i, being markedly different from that characteristic of
bituminous coal, 15 to i, but not so different from that of
cannel coal, 10*5 to i.
Some light on the probable origin of this kerogen has
been thrown by the recent researches of Hackford (Trans.
Am. Inst. of Mining and Metallurgical Engineers, 1920). He
found that by treating a Pennsylvania lubricating oil with
oxygen or sulphur at a temperature of only 100° C. practically
the whole, after a long period, gradually changed into bodies
practically insoluble in any of the known solvents. These
substances he termed kerotenes, and he found them to bear
a great resemblance to the kerogen of shales. Naturally
occurring bodies, intermediate in character between petroleum
and these kerotenes, are indeed known, the asphaltites and
glance pitches. The following table illustrates this point : —
Substance.
Per cent, sol-
uble in carbon
bisulphide.
Per cent, sol-
uble in petro-
leum spirit.
Sp.gr. 0-645.
Per cent,
fixed carbon.
Asphaltmade from Mexican petroleum
Gilsonite
99'9
about 98
60
40 to 60
12
10 to 20
Barbados Manjak
about 98
25 to 30
25 to 30
Grahamite
. .
about 99
about i
45 to 55
Albertite
slightly
trace
about 55
The work of Hackford indicates that these bodies repre-
sent steps in a process of gradual change which petroleum
may undergo, the final result of which is the kerotenes,
which are certainly very similar to, if not identical with, the
kerogen of some pyrobituminous shales.
CHARACTERS OF OIL SHALES 101
On this view, then, an oil shale would appear to be the
result of such a change having taken place in a rock which
had been saturated with crude petroleum. This gradual
transformation has been termed " inspissation." Evidences
that this is actually going on in nature are not wanting.
Oil sands more or less weathered and oil from seepages,
and intruded asphalts have been shown to contain propor-
tions of insoluble kerotenes up to as much as 30 per cent.
The well-known albertite vein of New Brunswick is
connected with a bituminous sandstone which still contains
oil. There can be little doubt that this albertite, which so
nearly resembles coal in some respects, is a highly inspissated
petroleum product. The rocks which this vein traverses
have actually been converted into true kerogen-containing
oil shales.
This process of inspissation seems further to bring about
a concentration of the sulphur and nitrogen found in the
original crude oil. For example, many crude petroleums
contain less than i per cent, of sulphur, the heavy asphaltic
oils of Mexico 5 per cent., the thiokerite wurzilite 5*8 per
cent., and a similar thiokerite from Nova Zembla as much
as 15 per cent. (Hackford. loc. cit.). Ohio crude oil contains
0'2 per cent, of nitrogen, some Calif ornian oils 175, and
albertite 175 per cent. The relatively high nitrogen and
sulphur content of shales perhaps also lends support to the
view that oil shales are merely shales (or other types of
rock) which were once impregnated with crude oil, which
has slowly undergone inspissation in the manner suggested
above. As Craig says, " an oil-shale field may be considered
as the relics of a former oil-field."
Conacher, on the other hand (Geol. Soc., Glasgow, 1916, p.
164), considers that the organic matter in the shale is of vege-
table origin, partly resinous in character. As the solubility
of resins decreases with age, the failure of solvents to extract
the organic matter from shales does not disprove this theory.
Hngler (Petroleum, vol. 7, p. 399) considers that the pyro-
bitumens of shales are of vegetable origin, formed perhaps
with such bodies as montan wax, as intermediate products.
102 PETROLEUM AND ALLIED INDUSTRIES
It is interesting to note in this connection that Jones
and Wheeler (J.C.S., 1916, p. 767) state that coal can be
resolved into cellulosic and resinic parts, the former of
which on distillation yields phenolic bodies, the latter
hydrocarbons.
Oil shales differ greatly in character. It is highly
improbable that shales so diverse in character should have
similar origins. Some would appear to be derived from
petroleum, others directly from organic matter. As in the
case of crude petroleums, the question of their origin is at
present far from being decided.
For comparative purposes a few shale analyses are
appended : —
Locality.
Sp.gr. of
shale.
Volatile
matter.
Fixed
carbon.
Ash.
Sulphur.
Scotland —
o/
/o
o/
/o
o/
/o
o/
/o
i. Torbanite
I-27
61-42
8-81
29-17
0-277
2. Cobbinshaw
1-62
37-16
8-24
53-64
1-435
3. Tarbrax
1-81
30-86
8-82
5871
3-053
4. Newliston
1-81
27-38
8-78
62-27
I'lIO
5. Hayscraigs
2-05
22-43
5-15
70-70
Q-622
6. Deans
2-23
15-28
4^3
77*7
0-528
Kimmeridge
39'i
n-8
46-6
—
tl
—
22-7
11-7
65-6
—
Norfolk
I '3
35'i
I5-3
39'8
—
,,
— .
32-9
9-0
55-o
4-0
Colorado
i '95
37'5
5'°
56-8
I '2
Locality.
Imperial gallons
per ton.
Lbs. ammonium
sulphate per ton.
Albert, N.B.
35
47
Argentina, Rio Grande
So
California, Kern Co.
52
—
Santa Maria
32
—
Esthonia
1 60
,
France, Autun
18
27
Kentucky
23
98
New South Wales, Newne
80
—
New Zealand, Waikaia
38
19
Picton, Nova Scotia
14
41
Queensland, Narrows
28
47
Scotland, Broxburn
37
12
Fells
26-40
20-35
,, Raeburn
54
7
Tasmania, Mersey
40
Transvaal
28
Utah
40
17
DISTRIBUTION OF OIL SHALES 103
As the variation in character, even of different seams in
the same group, is so great, generalizations about the cha-
racters of various shales in various localities cannot be drawn
with any degree of accuracy.
A scientific classification of shales is hardly yet possible.
They may, however, be roughly grouped into asphaltic
pyrobituminous shales, i.e. those of which the organic
matter contains little or no oxygen, such as those of New
Brunswick and Nova Scotia, and non-asphaltic pyrobitu-
minous shales, i.e. those of which the organic matter does
contain oxygen. This class includes cannel coals, torbanites,
and many oil shales (McKee and Lyder, /. Ind. and Eng.
Chem., 1921, p. 613).
Oil shales are widely distributed and found in many parts
of the world where oil has not yet been proved to exist.
In the British Isles shales are found in Scotland, in the
Lothians on the south side of the Firth of Forth, where a
thriving industry has now been established for more than
half a century. The shales here occur in the calciferous
sandstone series, the lowest division of the Carboniferous
system (Cadell and Wilson, " The Oil Shales of the Lothians,"
Memoirs Geological Survey, Scotland) .
The Torbane Hill shale, which was extensively worked
there, at one time yielded from 80 to 130 gallons of crude oil
per ton. This material has now, however, been completely
exhausted. The shales now worked yield on the average
not more than 20 to 30 gallons of crude oil per ton, but yield
also about 60 Ibs. of ammonium sulphate to the ton. The
shales from individual seams show great variation, some of
those worked yielding only 16 gallons of oil to the ton, others
as much as 50.
Extensive oil-shale deposits are now being developed in
Norfolk, England (Forbes-Leslie, J.I.P.T., 1916, p. 3).
The dip of the strata here is very gentle and the covering
surface deposits are thin, so that the shale can be quarried
from the surface. These shales are richer than those
of Scotland, and it is claimed that the crude oils resulting
from the distillation are of good quality and can be easily
104 PETROLEUM AND ALLIED INDUSTRIES
refined in spite of their high sulphur content. The industry
in Norfolk, however, is in its infancy, so developments will
be awaited with great interest. These shales are of the same
age as those which are found in Dorsetshire in the Kimmeridge
Clay. These latter shales were actually worked as far back
as 1848, and for the following twenty years or so various
companies attempted to carry on the industry but in every
case without success. The crude oil from Kimmeridge
shale is very rich in sulphur compounds (the crude oil
containing about 8 per cent, of sulphur), and as these com-
pounds are as stable as the hydrocarbons themselves, no
methods of successfully refining this oil have yet been evolved
(Mansfield, J.I.P.T., vol. 2, p. 162).
The shale-oil industry in France dates back to 1830.
The deposits at Autun and at Broxiere I^es Mines have an
annual output of about 750,000 tons of shale. These
shales yield about 50 gallons of oil to the ton. Richer
shales, yielding 80 to 120 gallons per ton, are also worked
in the Riviera (Petroleum Times, September 20, 1919).
Oil shales occur also in Wurtemburg, Spain, Sweden,
Italy, Bulgaria, Turkey, and Austria (Journal Royal
Society of Arts, December 24, 1920), but none of these
deposits have yet been commercially exploited. In Canada
vast deposits are found.
The rich shales of Esthonia have recently given rise to
an industry. They are used for (i) distilling to obtain oils,
(2) for gas making, (3) mixed with pulverized coal for
cement burning, (4) as fuel in place of coal. These shales
are very rich, yielding 29 per cent, of oil, i.e. about 75 gallons
to the ton (Shale Rev., 1921, Nos. 4, 5).
In Canada vast deposits are found in Northern Saskat-
chewan. In New Brunswick oil shales are found in three
areas. These yield from 27 to 57 gallons per ton of crude
oil, varying in specific gravity from 0-890 to 0-925, and
ammonium sulphate in quantities varying from 30 to no Ibs.
per ton. These shales are now being exploited (R. Ells,
"The Bituminous Shales of New Brunswick and Nova
Scotia," Canada Dept. of Mines, 1910). The oil shales of
DISTRIBUTION OF OIL SHALES 105
Nova Scotia are relatively poor in respect to both oil and
ammonium sulphate. Those of Newfoundland cover a
large area and yield about 50 gallons crude oil and 80 Ibs.
ammonium sulphate per ton. Deposits of similar character
are found in the province of Quebec.
In the United States, vast deposits of oil shale occur,
those of Colorado alone covering an area of 2500
square miles, being estimated to be capable of supplying
8,000,000,000 tons of crude oil. In Utah more than
40,000,000,000 tons of shale capable of yielding 35 gallons
to the ton are available. Those of Kentucky yield 22
gallons of oil and 97 Ibs. of ammonium sulphate per ton.
Wyoming, Texas, Montana, and West Virginia possess
extensive deposits, as do also California, Kansas,
Oklahoma, Nevada, and New Mexico.
Vigorous efforts are now being made in the United States
to set the oil-shale industry on a sound economic footing.
Shales in the Transvaal have yielded from 30 to 90
gallons of crude oil to the ton, but the beds are usually thin
and therefore expensive to work (T. G. Trevor, "An Oil-
Shale Industry for South Africa," South African Journal
of Industries, August, 1920).
There are indications too of extensive deposits in Brazil
and in China.
Extensive deposits of rich oil shales are found in the
Wolgan Valley area in New South Wales. These have been
worked for some years, but so far with disappointing results.
In New Zealand and Tasmania oil shales are also known.
These latter deposits have been estimated at 5,000,000
tons and are now in process of development.
GENERAL REFERENCES TO PART IV., SECTION A.
Alderson, " The Oil-Shale Industry." F. A. Stokes Co., New York.
Baskerville, " American Oil Shales." /. Ind. and Eng. Chem., vol. 5,
1913, p. 73.
Cronshaw, " Oil Shales." Imperial Institute Monograph. J. Murray,
1921.
Greene, " A Treatise on British Mineral Oil." Griffin and Co.
Quarterly Journal of the Colorado School of Mines.
Scheithauer, " Shale Oils and Tars." Scott, Greenwood and Co.
SECTION B.— THE MINING OF SHALES
THE shale-oil industry, in contrast to the petroleum industry
proper, must always be severely handicapped by the fact
that the crude shale oil, the real starting point for the manu-
facture of the oil products, must in every case be manu-
factured. The factor of the cost of mining the shale becomes,
therefore, one of supreme importance, the more particularly
so as the percentage of oil derived from the shale is often
less than twenty. The cost of mining the shale, therefore,
will often be the factor which determines the chance of
success of any shale proposition.
The method of mining to be adopted in any locality
will depend upon various factors, such as the depth at which
the shale strata are found ; their dip or inclination to the
horizontal ; the thickness of the shale seams, and the
nature of the overlying beds.
The methods employed may be divided into two groups :
(a) The open cut or quarrying method.
(b) The mining methods.
In many localities, such as Grand Valley, Colorado,
the shale forms prominent hills, so that the shale can be
quarried by ordinary methods and transported by gravity
conveyors to the shale retorting plant at lower levels, this
being the cheapest method of working. In other areas,
such as Norfolk, the shale beds lie close to the surface with a
gentle dip. Under these conditions steam shovels may be
used. In any case, however, a considerable quantity of
surface material must be removed. The cost of such
operations is low, being only three or four shillings per ton.
In some cases, the shales may be worked by horizontal
1 06
THE MINING OF SHALES 107
adits driven into the side of a hill, as is the case in Wolgan
Valley, New South Wales.
In many cases, however, the shales may be at greater
depths, the strata being either inclined or more or less
horizontal. In such cases ordinary mining methods must
be adopted. A vertical shaft may be sunk from which the
level crosscuts may be driven ; or an inclined shaft may be
sunk along one of the beds of shale, from which the crosscuts
branch off.
The oil shales of Scotland are worked in this manner.
After the mine has been driven, the shale is worked either
by (i) the Stoop and Room method, or (2) the lyong Wall
method. A detailed description of the methods used is,
however, beyond the scope of this work. For such details
reference may be made to " The Oil Shales of the I^othians,"
Part II., by W. Caldwell, Memoir of Geological Survey of
Scotland, 1906.
The work of mining shale is generally simpler than that
of coal, as gas is absent. Moreover, grading is unnecessary
as all the shale from the seam being worked goes to the
retorts after being broken up to suitable size in the crushers.
SECTION C.— LABORATORY EXAMINATION
OF OIL SHALES
As the actual yield of products obtained on retorting will
naturally depend to a considerable extent on the method of
retorting employed, it is difficult or impossible to devise a
laboratory method of testing shales which will always give
results comparable with those obtained in practice. Never-
theless, some method of testing on the laboratory scale is
necessary, and highly useful, both for exploratory work and
for the control of operations on the large scale.
Moreover, if the relation between the laboratory results
and those obtained from large-scale operations has been
worked out in one case, other laboratory results may be
interpreted in the same way with the reservation, of course,
that such interpretation is not rigid.
Elementary analyses giving the nitrogen, carbon, and
hydrogen content can be easily carried out by the well-
established methods. Determinations of ash and volatile
matter are also easily made. Great care must, however,
be exercised in deducing conclusions from such elementary
analyses. The nitrogen content alone cannot indicate the
quantity of ammonium sulphate obtainable, because the
whole of the nitrogen cannot be converted into ammonia.
Many shales contain in their mineral matter appreciable
and often considerable amounts of carbonates, and also
combined moisture, the latter and the carbon dioxide in
the carbonates being evolved on ignition. The apparent
" volatile matter " derived from the organic matter is thereby
often materially increased, and in the elementary analysis,
the percentages of carbon, hydrogen, and oxygen in the
organic substance are also exaggerated. Hence, in the
108
LABORATORY EXAMINATION OF OIL SHALES 109
majority of cases few deductions of value can be made from
either the elementary analysis or from the determination
of volatile matter, so without additional information the
results of such analyses may be very misleading.
The United States Bureau of Mines has for the present
adopted the method of laboratory testing of shales, as
worked out by Bailey, and applied to the control of shale
retorting in Scotland. Full details of the method are
published in " Notes on the Oil-Shale Industry " by Gavin,
Hill, and Perdew, Bureau of Mines, Washington, 1919,
from which the following description is abstracted :—
A malleable iron tube 6 feet long and 2 inches in diameter,
welded up at one end, is used as the retort. About 15 inches
of the tube is partly filled with shale crushed to pieces of
the size of peas. The tube is placed with about 18 inches
of its length (which contains the shale) in a furnace, the
other 4 1 feet projecting outside the furnace inclined down-
wards towards the open end, and acting as a condenser.
The tube is gradually heated by flue gases during six
hours, being finally heated to a bright red. The portion of
the tube projecting outside the furnace is then gradually
warmed so as to melt any oil which might have solidified
therein, and to enable it to run down into the collecting vessel
placed below the end of the tube. The oil must be separated
from the water which comes over with it, or the water in
the mixture must be estimated by one of the standard
methods, e.g. by distillation with xylene.
The yield of ammonium sulphate is estimated in a
similar fashion. A i-inch tube of malleable iron about
28 inches long is used. One end is connected to a steam
supply, the other to a wash bottle or tower containing dilute
sulphuric acid (2N), an empty flask to act as receiver being
placed between the end of the iron tube and the sulphuric
acid container. About 30 grams of the shale are placed
in the centre of this tube, which is heated to bright redness
in an ordinary combustion tube. After 5 or 6 minutes' gentle
heating, when vapours begin to appear in the flask, steam is
allowed to pass through the retort at such a rate that after
no PETROLEUM AND ALLIED INDUSTRIES
about ij hours' heating to bright redness about 600 c.c. of
liquid has collected in the flask. The contents of the flask
and sulphuric acid absorber are then filtered and washed
into a litre flask and made up to a litre, so that three succes-
sive portions can be removed for estimation. This may be
done by concentrating by evaporation, the nitrogen in the
concentrate being estimated by the nitrometer.
The United States Geological Survey (Bulletin No. 641,
p. 148) have standardized a simple apparatus for field
work. It consists merely of a small iron retort of about a
half-pint capacity fitted with closely fitting iron lid with
clamps, which can be heated by a kerosene burner, and which
is connected to a small metal I^iebig condenser. The
condenser is connected to a flask with a two-holed cork, one
of which takes the end of the condenser, the other a glass
tube to lead the permanent gases to an ammonia scrubber.
A well-mixed sample weighing 8J oz. is taken, ground so as
to pass through a J-in. sieve. The number of cubic centi-
metres of oil obtained is equal to the yield of oil in U.S. gallons
per ton' of shale, provided that 8J oz. of shale be taken for
the experiment.
The percentage of nitrogen given by the elementary
analysis multiplied by 94 gives the approximate yield of
ammonium sulphate in Ibs. per ton which may be expected.
It must be remembered, however, that the yield of nitrogen
as ammonia depends on the amount of steaming given.
A modified method of laboratory analysis, which allows
both oil and ammonia yield to be determined simultaneously,
is described by lyomax and Remfry (J.I.P.T. vol. 7,
1921, p. 36). These two investigators have noticed the
surprising fact that the changes which take place during
the weathering of shale affect to a considerable extent the
obtainable yield of oil. After a short period of exposure
to the weather, the oil yield is found to improve by as much
as 20 per cent, in some cases, but after longer exposure
falls again, reaching its original value in the course of a
month or two and then falling still lower. It is evidently
important to seize the right moment for retorting the shale.
SECTION D.— THE RETORTING OF OIL
SHALES
As the oil obtained from oil or pyrobituminous shales does
not exist as such in the shale, but is formed during the
process of retorting, the questions, what takes place in the
retorting process, and how far the conditions of retorting
affect the yield and quality of the product, are of the very
greatest importance.
It has long been recognized that the changes taking place
in the retort are of a twofold nature, viz. (i) the production
of certain volatile compounds by the thermal decomposition
of the pyrobituminous constituents of the shale, and (2) the
subsequent cracking or further decomposition of these
primary volatile products. It has also been regarded as
probable that considerable chemical changes take place
by the action of heat even before the above-named primary
volatile products make their appearance, and recently this
view has been experimentally verified. Messrs. McKee
and Lyder (/. Ind. and Eng. Chem., 1921, 613, 678) have
studied this point and have shown that whereas the pyro-
bituminous constituents of the original shale are scarcely
soluble in neutral organic solvents such as carbon bisulphide,
if the shale is heated for some time at a temperature just
below that at which volatile products are evolved in appreci-
able amount, the pyrobituminous portion undergoes change
into a heavy bitumen which is then for the most soluble in
carbon bisulphide. In the case of a certain Colorado shale
which they investigated, this first resolution of the original
pyrobituminous matter into simpler but still very complex
substances took place at temperatures of 400° to 410° C.,
and a slight further increase of the temperature above
in
H2 PETROLEUM AND ALLIED INDUSTRIES
410° brought about cracking and the production of light
hydrocarbons.
These results verify the above-mentioned view that two
quite distinct sets of chemical reactions take place in the
process of retorting. The retort functions not only as a
producer of a bituminous substance, but also as a cracking
still.
Two distinct reactions thus take place, the second
following closely on the heels of the first. It is, however, of
importance that the second stage, viz. the cracking, should
be under control to some extent at any rate. The question
of the control of this cracking is, therefore, one of the most
important factors which should influence retort design.
As all pyrobituminous shales leave a more or less carbon-
aceous residue on retorting, the question of the utilization
of this carbon, and also of the nitrogen contained in the
residue is also of great importance.
This may be effected by the introduction of steam alone
where the carbon content of the residue is low, or of steam
with a limited amount of air where the carbon content is
higher, into the bottom of the retort whereby the residue
is converted into water gas or producer gas and ammonia,
the latter being recovered in the well-known manner, and the
former mixing with the gas formed from the bituminous
matter. This gas after separation of the oils is used for
heating the retorts or other purpose if there is any surplus.
In addition, however, such water gas or producer gas produc-
tion has a marked effect on the oil production of the shale,
as the sensible heat of this gas assists largely in the thermal
decomposition of the shale through which it passes, thus
considerably reducing the time required for completion of
the elimination of the oil from it. When the percentage of
carbon in the residue is fairly high, the sensible heat in the
producer gas thus made is in itself sufficient to effect the
removal of all the volatile matter from the shale, and no
external heating of the retort is required.
Such production of water gas or producer gas within the
retort has the further result that the primary oil vapours are
THE RETORTING OF OIL SHALES 113
removed from the zone of heat more rapidly, and the crude
oil produced contains a larger proportion of saturated hydro-
carbons. The decomposition of the shale and the subsequent
cracking of the primary vapours also then take place in an
atmosphere containing a much larger proportion of hydrogen
and steam, and this further favours the production of satu-
rated Irydrocarbons, and consequently improved quality of
the crude oil obtained.
Certain disadvantages follow from such production of
water gas or producer gas in the retorts, although these are
far outweighed by the above-mentioned advantages. Thus
the higher production of gas involves a greater cost for con-
densing and scrubbing apparatus, and the large volume of
gas carries away from the condenser most of the lighter
hydrocarbons in the form of vapour, making their recovery
by oil-washing more expensive.
The principal points to be borne in mind when considering
the design and functions of a retorting plant are —
(a) The carrying out of the initial stages of the distillation
at as low a temperature as possible. This is necessary in
order to obtain relatively large oil and small gas yields, and
to obtain oil of paraffinous rather than of aromatic nature.
(b) Efficient arrangements for removing the vapours
from the retort as soon as possible, and for ensuring that they
come into contact with highly heated shale and retort walls
as little as possible, in order to avoid secondary reactions
and cracking or decomposition of the oils first formed.
(c) The necessity of ensuring efficient transfer of heat
through the mass of shale to be retorted. As the shale
is such a poor conductor of heat, either the layer of shale in
the retort must not be more than a few inches in thickness,
or mechanical means of keeping the shale in motion must be
adopted.
(d) Arrangements for enabling the shale to be further
distilled in contact with steam, either in the same or in a
separate retort, in order to obtain the maximum ammonia
yield.
(e) The problem common to all plants, that of efficient
p. 8
ii4 PETROLEUM AND ALLIED INDUSTRIES
utilization of heat as far as possible, i.e. minimum fuel
consumption.
(/) Simplicity of operation and control.
(g) Capacity for working continuously over long periods,
with high rate of throughput and low maintenance costs.
(h) I,ow initial capital expenditure.
In the case of plants for the low-temperature distillation
of coal, or at any rate of caking coals, the difficulties caused
by the caking into a sticky mass of the intumescing coal
and its consequent inability to pass down the retort, are so
great that, up to the present, no really good type of retort
has been handled for dealing with such coals.
McKee and lyyder have also determined some data,
which will be useful for designers of shale retorts.
The heat required to convert the kerogen into oil was
found to vary from 421 to 484 calories per gram of oil and
gas produced, in the cases of the three shales investigated
by them. The heat conductivity of the shale was found to be
0*00086 in c.g.s. units and the specific heat about 0*265.
Outside of Scotland, few shale-oil works of any large
capacity exist. It will be as well, therefore, to describe
the retorting process as used in Scotland, before considering
the very numerous types of retorts designed and patented,
but so far not found working in practice on a large scale.
The shale is first broken up into small pieces before
being fed into the retort hoppers. The type of crusher used
depends to a large extent on the nature of the shale. The
tough Scottish shales are broken up in a heavy toothed
roller machine. For more brittle shales a head motion jaw-
crusher will prove more satisfactory. In crushing shales
any rubbing or grinding movement should be avoided in
order to minimize the production of dust or fines, as the
presence of dust gives trouble owing to the clogging up of
the condensing plant.
The shale retorts employed in the " Scottish shale-oil
industry are all modified forms of the original Young and
Beilby continuous vertical retort brought out in 1882.
One of the most successful of these is the Pumpherston
THE RETORTING OF OIL SHALES 115
or Bryson type. This retort is made up of two parts
The upper is of cast iron, 15 feet long, 2 feet in diameter
at the top, tapering to 2 feet 4 inches at the lower end. The
Y///////////,
\\\\\\\\
FIG. 1 6. — Bryson shale retort.
lower portion is of firebrick, 20 feet in length, 2 feet 4 inches
diameter at the top where it joins the cast-iron upper part
tapering to 3 feet at its lower end. This retort is circular
in cross section. A few inches below the lower end of the
n6 PETROLEUM AND ALLIED INDUSTRIES
retort is a circular table on which the spent shale rests. On
this table works a revolving arm which slowly scrapes the
spent shale over the edge of the table, thus providing con-
tinuous removal of the spent shale from the retort, enabling
supplies of fresh shale to be fed in continuously through the
hopper at the top.
The upper iron portion of this retort is kept at a dull
red heat, and it is in this section that the oil distillation
takes place. The oil vapours pass out just below the hoppers,
into a large main.
In the lower firebrick portion of the retort the shale
is subjected to a higher temperature in presence of steam, the
carbon of the residue being converted into carbon monoxide,
and the nitrogen partly into ammonia, this part of the
retort thus functioning as an ammonia and gas producer.
With a retort of the above dimensions about 4 to 5 tons
per day of shale yielding say 25 gallons per ton of oil can be
handled. For each gallon of oil produced about 4 gallons
of water in the form of exhaust steam is introduced into the
bottom of the retort. This steam serves several purposes ;
it absorbs a certain amount of heat from the spent shale,
produces water gas from the fixed carbon left in the shale
after distillation, produces ammonia (about 60 per cent, of
the total nitrogen of the shale being so recovered), helps
to equalize temperatures throughout the cross section of
the retort and to carry off the vapours. A discussion of the
action of steam on yield of ammonia in this connection is
given by A. J. Franks in Chemical and Metallurgical
Engineering for December 15, 1920, p. 1149. Franks
points out that the steam has a synthetic action at high
temperatures and that it removes the ammonia so formed
before decomposition can take place to any great extent,
the rate of dissociation of ammonia at the temperatures in
question being low.
The quality of the oil obtained depends on the temper-
ature employed in retorting. The higher the temperature
the greater the proportion of unsaturated hydrocarbons in
the oil, the greater the subsequent loss in refining the crude
THE RETORTING OF OIL SHALES 117
oil, and the lower the proportion of paraffin wax (Stewart,
J.S.C.I., 1889, p. 100).
The gases evolved after passing through the scrubbers
and condensers are used for heating the retorts, no extra
fuel being necessary.
There are three other types of retort in use in Scotland,
viz. the Henderson, Young and Fyfe, and the Crichton.
These are all similar in principle, being based on the original
Young and Beilby retort.
Although such retorts have given very satisfactory
results with Scottish shales, it by no means follows that they
can be applied with equal success to all shales, as shales from
different localities exhibit very great differences in character.
Nor may it be taken for granted that these types are the
best possible even for*-Scottish shales. The throughput per
retort is very low and the capital expenditure on plant
therefore high. The chief difficulty in designing a vertical
gravity feed retort of this type arises out of the low thermal
conductivity of the shale. If the centre of the mass under-
going distillation be more than a few inches from the retort
wall, the heat transference is so poor that either the internal
mass does not attain a temperature sufficiently high, or the
portions of the shale near the retort wall are subjected to a
temperature too high, resulting in excessive cracking of the
oil and diminished yield.
Numerous other types of retorts have been devised,
few of which have passed and many of which have never
reached the large-scale experimental stage. These types
may be divided into classes —
(a) Continuous vertical with gravity feed (the Scottish
type).
(b) Continuous vertical type with some form of mechanical
feed.
Examples of this type are the Colorado continuous,
fitted with a helical conveyor, and the Simpson, fitted with
a means of keeping the charge in continuous movement
by means of two revolving rollers at the base of the
retort. An interesting retort of this class is that recently
n8 PETROLEUM AND ALLIED INDUSTRIES
designed by Freeman (Pet. Times, January 14, 1922, p. 43).
This retort is made up of a number of distinct chambers
set vertically one above the other. Each chamber is
separately heated by gas burners and the temperature is
accurately controlled by a special automatic apparatus.
The finely divided shale rests on a revolving table in each
chamber and is transferred gradually from one chamber to
the next below it by means of revolving arms, the action
being similar to that of a pyrites burning oven. Each
chamber is provided with separate vapour off-take pipes.
One advantage which this retort possesses is that of the
driving off of the water mostly in the first chamber so that
emulsified oil distillates are largely avoided.
(c) Horizontal continuous types fitted with mechanical
feed.
Examples of this are the Del Monte, a tubular externally
heated retort fitted with an internal worm, and the Thyssen,
the retort being slightly inclined and revolving like a cement
kiln, but with external heating.
(d) Horizontal continuous type fitted with mechanical
feed and internal heating, e.g. the Burney retort. This is of
several feet diameter, and is fitted with a large internal screw,
through the vanes of which the heating gases pass, the
difficulty of heat transmission thus being to some extent
avoided.
(e) Types in which the heating is effected internally and
directly by means of the sensible heat of gases.
Examples of this are the Maclaurin type which has had
some success even when applied to the low-temperature
distillation of coal, and the Nielsen, which consists of an
inclined rotating cylinder, in which the shale is heated by
direct contact with the heated gases from a producer in
which a part of the carbonaceous residue is treated.
A summary of the forms of plant used or under trial in
America for shale retorting is given in the Chemical Age,
New York, Januan^, 1921, vol. 29, p. 30.
As practically all oil -shale retorts, with the exception of
those used in Scotland, are as yet in the experimental stage,
THE RETORTING OF OIL SHALES 119
the writer feels that no opinion of value as to their relative
merits can as yet be formed.
It would appear, however, that retorts constructed on
the principle of heating by direct contact with heated gases,
products of combustion, or better, heated combustible gases
from a producer, could be constructed of large dimensions
with great potentialities as to throughput, the difficulties
dependent on the low. thermal conductivity of the shale
being in such cases overcome. One objection to this type
is the dilution of the oil vapours with large volumes of
gases, which renders condensers of greater capacity
necessary (Simpson, " Plant Design for Hot Gas Pyrolytic
Distillation of Shale," Chem. and Met. Eng., 1921, p. 341).
The issuing gases and vapours from the retorts are often
passed through some form of centrifugal separator, their
temperature being kept above 100° C. The heavier portions
of the distillate are thus collected free from water. The
remainder of the vapours are then condensed in water-cooled
condensers, then passed through scrubbers in contact with
sulphuric acid for the purpose of removing ammonia, then
through scrubbers in contact with heavy oil, to which the
vapours give up the last traces of volatile fractions. The
residual gas leaving the scrubbers is used for heating the
retorts or for other purposes in the works.
GENERAL REFERENCES TO PART IV., SECTION D.
Ells, " Bituminous Oil Shales of New Brunswick and Nova Scotia."
Canada Department of Mines.
Greene, " Treatise on British Mineral Oils." Griffin and Co.
Scheithauer, " Shale Oil and Tars." Scott, Greenwood and Co.
Stewart, " Oil Shales of the Lothians." Memoir of Geological Survey.
SECTION E.— THE CHARACTERS OF SHALE
OILS
THE crude oils derived from the retorting of shales exhibit
great differences in character, dependent on (a) the nature of
the pyrobituminous organic matter of the shale, and on
(b) the conditions under which retorting is effected.
Although resembling to some extent crude petroleums,
shale oils usually exhibit special characters in consequence
of their relatively high content of unsaturated hydrocarbons.
The method of determining the unsaturated hydro-
carbons present is somewhat rough and ready, but serves
the purpose sufficiently well. The crude oil is treated with
two volumes of sulphuric acid (sp. gr. 1-84) and allowed to
settle out. The volume of the oil remaining, expressed in
percentage of the volume of oil taken, gives the percentage
of saturated hydrocarbons. The difference is not strictly
due to the absorption of unsaturated hydrocarbons only,
as basic nitrogen compounds may be present, certain
aromatic hydrocarbons may be absorbed, and certain com-
pounds may be polymerized and subsequently dissolved by
the sulphuric acid.
A number of shale oils examined in the laboratory of
the Colorado School of Mines (C. W. Botkin, Chem. and Met.
Efig., 1921, p. 876) gave the following results : —
Shale Per cent, of saturated
retorted. hydrocarbons in the oil.
Colorado . . . . . . 13-6 to 28 '0
Utah 15-8 to 26-5
Nevada . . . . . . 41 '2
Kngland . . . . . . 16*0
vScotland . . . . . . 38-0
The high content of unsaturated hydrocarbons as
compared with petroleums is due to the low content of
120
THE CHARACTERS OF SHALE OILS 121
hydrogen of the kerogen, there being insufficient to combine
with the carbon. Even although so large a proportion of
unsaturated hydrocarbons are produced, there is always
free carbon left in the shale residue.
The ratio of carbon to hydrogen for the kerogens of
shales varies approximately from 7 to 8 or more, whereas
the ratio for paraffins, such as are usual in petroleum, varies
from 5 to 6. Moreover, it is probable that some of the
saturated hydrocarbons formed during the distillation
undergo secondary cracking, with the further production of
unsaturated hydrocarbons.
The probability of this cracking indicates the necessity
for designing the plant and carrying out the retorting so
as to remove the products of distillation as soon as
formed.
A series of experiments to investigate the influence of
temperature in retorting and the influence of steam or
hydrogen gas were carried out on Colorado shale oil in the
laboratory of the Colorado School of Mines (Quarterly of the
Colorado School of Mines, vol. 16, No. 2, April, 1921).
Retorting was carried out under four different conditions :
(a) at low temperature without use of steam, (b) at low
temperature with use of steam, (c) at low temperature with
hydrogen in place of steam, (d) at higher temperatures, the
oil being partly returned to the retort by means of a reflux
condenser so as to obtain good cracking conditions.
It was found that under none of these conditions was
(i) oil obtained from that particular shale containing less
than 70 per cent, of unsaturated hydrocarbons. This is, of
course, primarily due to the low hydrogen content of this
shale. (2) That the presence of free hydrogen had no effect
other than that of diluting and assisting in the removal of
the vapours, a function performed equally well by steam.
(3) That when the cracking is minimized by the use of steam,
the unsaturated hydrocarbons are actually about 15 per
cent, higher than when the cracking is at its maximum.
This latter result is, at first, rather surprising, but it is
explained by the fact that the yield of oil is 10 per cent.
122 PETROLEUM AND ALLIED INDUSTRIES
less, owing to the cracking of unstable, unsaturated hydro-
carbons with the formation of coke and some lighter
saturated oils. This is an extremely interesting result as it
indicates that it may be more economical to retort at higher
temperatures, the loss in yield of crude oil being, perhaps,
counterbalanced by the lower loss in the subsequent refining
operations. ,
These conclusions were further borne out by the be-
haviour of the resulting oils on distillation. The oil obtained
by the low-temperature steam distillation containing 85*4
per cent, of unsaturated, cracked to the greatest extent,
yielding 10 per cent, of coke, 2*95 per cent, of gas, and 86*6
per cent, of oil containing only 65 per cent, of unsaturated
hydrocarbons.
This work was followed up by an examination of the
effect of distillation on various shale oils, from which the
following conclusions were drawn : (i) There is a large
amount of decomposition during the subsequent distillation
of the crude oil, this being least for parairmous, and most
for asphaltic oils. (2) The cracking is most rapid when the
still temperature exceeds 320° C. (3) That the once run
oils are more stable and suffer relatively little cracking on
further distillation. (4) That the decomposition is appar-
ently one of heavy unsaturated compounds, which are
unstable at the still temperatures necessary for distillation
at atmospheric pressure, without the introduction of steam.
Stewart, " Oil Shales of the lyOthians," Memoir of
Geological Survey, Scotland, pp. 155-157, gives data re the
character of several crude oils from Scottish shales —
Specific gravity . . . . . . from 0*864 to 0*909
Setting point ,,67° F. to 93° F.
Benzine fraction 0730/0740 . . up to 4*65%
Burning oil 0*807/0-812 . . . . 15*92% to 40-59%
Medium oil 0*840. . . . . . up to 9*18%
Imbricating oil 0*865/0 '885 . . ,, 34-02%
Solid paraffin 114/116° F. . . about 10% to 15%
Loss in refining . . . . 24-55% to 35*94%
It will be noted that the loss in refining is many
THE CHARACTERS OF SHALE OILS 123
times greater than that incurred in working up a crude
petroleum.
A sample of Kimmeridge shale oil was found to have the
following properties : —
Specific gravity . . . . . . 1*009
Sulphur 5 -8 per cent.
Viscosity Redwood I. at 70° F. 62 seconds
Engler at 20° C. . . 2 '2
Paraffin wax . . . . . . 1/2 per cent.
Fraction to 150° C. . . . . Sp. gr. 0-867. Sulphur
7 '2 per cent. Saturated
hydrocarbons 10 per
cent.
Fraction 150° C. to 270° C. . . Sp. gr. 0-936. Sulphur
4 'i per cent.
Residue 54 per cent Sp. gr. ro6o. Sulphur
4-1 per cent. Viscosity
Eng. at 20° C. over
200°.
A sample of fuel oil from Scottish shale oil was found to
possess the following characters : —
Specific gravity at 15° C. . . 1*009
Sulphur . . . . . . . . 0*46 per cent.
Calorific value ' 8347, i.e. 15,025 B.Th.Us.
Flash-point 140° F.
Viscosity Redwood I. at 70° F. 37 seconds
Tar acids . . . . . . . . 30 per cent, by volume.
The low calorific value is to be attributed to the high
percentage of tar acids.
It will thus be seen that shale oils differ materially in
character from crude petroleums. The presence of large
proportions of unsaturated hydrocarbons, renders their
refining into commercial products a difficult proposition, as
chemical reagents, which might be employed to remove
undesirable sulphur compounds, will also -attack the un-
saturated compounds. Moreover, unsaturated hydrocarbons
124 PETROLEUM AND ALLIED INDUSTRIES
are unstable, and water-white sweet products made from
them are very liable to change on standing. The quality of
a shale oil is thus in the present state of our knowledge
determined chiefly by its content of unsaturated hydro-
carbons. If some process of commercially converting un-
saturated into saturated hydrocarbons were only known,
the problem of the satisfactory utilization of many shale
oils would be much nearer solution. The methods of
working up Scottish shale oil are in the main those usually
employed in petroleum refining, for which reference may
be made to Part VII.
SECTION R— VARIOUS TARS
UNDER the term " tars " may be grouped a number of products
resulting from the distillation of coal, lignite, peat, wood, or
other organic material. Such products are described as
tars because, in addition to hydrocarbons, they contain
large proportions of other bodies such as phenols and
nitrogen bases. Moreover, their hydrocarbon constituents
are often very different from those normally occurring in
petroleum. The chief examples of this class are the tars
derived from the carbonization of coal under various con-
ditions, e.g. horizontal coal tar, vertical coal tar, low- tempera-
ture coal tar, and coke-oven tar, together with tars such as
Mond-gas tar and blast-furnace tar. Tars resulting from
the distillation of peat, lignite, wood, etc., are of less common
occurrence.
As the subjects of the production of tars or liquid fuels
from coal, lignite, peat, and wood, have been dealt with in
the book of this series of H. S. Taylor on " Fuel Production
and Utilization," little need be said here. A description of
the methods adopted for the distillation of coal in coke
ovens or low-temperature carbonization retorts is quite
beyond the scope of this work. The reader may be referred
to such works as V. B. I^ewes, " The Carbonization of Coal,"
Benn Brothers. The subject of low- temperature carboniza-
tion of coal has received much attention during the last few
years, but its successful commercial development has not
yet been assured. Apart from the questions of marketing
of the solid carbonaceous residues, and the low-temperature
tars, the engineering difficulties of designing suitable retorting
plant, especially in the case of caking coals, are much greater
than those met with in the designing of plant for the
distillation of pyrobituminous shales. In character the various
125
126 PETROLEUM AND ALLIED INDUSTRIES
tars resulting from the distillation of coals of different types
under various conditions are intermediate between ordinary
horizontal coal tar on the one hand, and crude petroleum on
the other. The character of these tars can best be explained
by comparison with these two extreme types.
In general, the character of a coal tar depends on the
temperature at which carbonization takes place. The tars
derived from horizontal gas-works retorts, which are
operated at high temperatures, are rich in aromatic hydro-
carbons and practically paraffin free; those from low-
temperature carbonization are rich in paraffin, and poor in
aromatics. Coke-oven tars, and tars from vertical gas-works
retorts are intermediate in character between these two
extreme types.
This difference in character is largely due to the secondary
reactions which take place in the highly heated horizontal
retorts, the paraffin hydrocarbons first formed being cracked
into aromatic hydrocarbons, hydrogen, and coke. In
consequence of this, high-temperature tars are relatively
rich in so-called " free carbon," insoluble in carbon bisulphide,
low-temperature tars containing sometimes as little as
one per cent.
I,ow-temperature tars are richer in tar acids, the cresols
and higher homologues predominating over phenol.
High-temperature tars contain much naphthalene, low-
temperature tars little or none.
The nitrogen of high-temperature tars is largely in the
form of pyridin homologues, of low-temperature tars largely
in the form of aniline.
The following table indicates the chief points of difference
between these tars : —
Sp.gr.
Per
cent, tar
acids.
Per
cent,
free
carbon.
Per
cent,
naph-
thalin.
Aroma-
tic con-
tent.
Per
cent,
pitch.
Horizontal
I'22
3
2O
10-15
rich
65
Coke oven
ri8
5
12
10
60-65
Vertical
Low-temp, carbonization
I'lO
7
12
4
2
5-10
o
\
r
40-50
Peat
o-99
10
I
0
poor
3°
VARIOUS TARS 127
The above figures are approximations only, and may
serve merely to indicate the general relations of the various
tars. The characters of individual tars of any one class
show great variation.
The fundamental difference between such tars as a whole
and crude petroleum is indicated also by their elementary
analysis. The ratio of the content of carbon to that of
hydrogen ranges from 8 to n for the tars, whereas, even
for heavy petroleum it is not more than 8, and for the lighter
as low as 5*5. This, relative shortage of hydrogen, together
with the presence of oxygen, is the chief cause of the great
difference between tars and petroleum oils. Tars of the low-
temperature type may yield small percentages of light
hydrocarbons suitable for motor use. After these have
been removed the residue is only fit for use as liquid fuel, at
the present day at any rate.
Such tars serve as reasonable fuels for furnace use.
Their calorific powers are, however, relatively low compared
to those of petroleum fuels, say 16,000 as compared with
18,000 B.Th.U. Owing to their content of pitch they cannot
be blended with a fuel of petroleum origin, owing to the
precipitation of the pitch. Such low-temperature tars may
also be successfully used as diesel engine fuel. In addition to
low-temperature tars made by the direct distillation of coal,
other types such as producer-gas tar, which is condensed out
of producer gas, blast-furnace tar, condensed out of blast-
furnace gases, and Mond-gas tar from Mond-gas producers,
are also produced in relatively small quantities. These tars
are similar in their general character to low-temperature
tars and need not be further described.
In Saxony there exists quite a considerable industry,
dependent on rather peculiar types of lignite. These
lignites contain a bituminous material which is soluble in
solvents, such as benzene, carbon tetrachloride, ether, or
acetone. The material so extracted is utilized for the
preparation of montan wax, which is described in Part VI.
These lignites on distillation yield tars rich in paraffin
wax. When raised from the mine these bituminous
128 PETROLEUM AND ALLIED INDUSTRIES
lignites present a greasy brownish appearance, and dry to a
lighter colour, the richest of them, viz. the peculiar material
termed " p}aopissite " being yellow in colour. This has
a specific gravity of about ro, whereas ordinary or pyro-
bituminous lignites have specific gravities ranging from
i '2 to 1-4.
Various types of retort have been used, the most successful
being that devised by Rolle, which works continuously.
This retort consists of a cylindrical firebrick structure
about 20 feet high and 5 to 6 feet internal diameter. Inside
this cylindrical retort is built up a series of bevelled iron
rings superimposed one on the other, forming an internal
core or cylindrical chamber, the surface of which presents
the appearance of louvre boards. The lignite is fed by
means of a hopper into the annular space between the
central cast-iron chamber and the outer firebrick cylinder.
Distillation is effected in this annular space by the heat
transmitted through the walls of the outer cylinder, which
is heated by flues as in the case of the Scottish type of retort
described previously. The vapours liberated pass between
the cast-iron rings into the centre of the chamber, whence
they pass off by the vapour delivery pipe.
The tars obtained from the distillation of such lignites
and from pyropissite in particular (which may yield up
to 20 per cent, of tar) are light (the specific gravity
varying from 0*8406 to 0*910), and are rich in paraffin
wax.
The vast quantities of peat found in various parts of
the globe will doubtless one day also serve as a basic material
for the manufacture of fuel and other oils.
Up to the present, however, little has been done in this
direction except in Germany, the removal of the large
percentage of water found in all peats presenting an economic
difficulty. The nature of the oil obtained depends on the
nature of the peat and on the method of distillation. Peat
oils mainly composed of saturated hydrocarbons have been
described, also others composed largely of unsaturated.
Peat tars contain tar acids in large quantities, usually
VARIOUS TARS 129
also paraffin wax, and yield a useful soft pitch as distillation
residue (Technical Paper, No. 4, Fuel Research Board).
GENERAL REFERENCES TO PART IV., SECTION F.
Berthelot, " La technique moderne de 1'industrie des goudrons de
houille," Revue de Metallurgie, 1920, p. 64.
Gluud, " Die Tieftemperaturverkokung der Steinkohle, 1921." Knapp,
HaUe.
Gregorius, " Mineral Waxes." Scott, Greenwood and Co.
Greene, " Treatise on British Mineral Oils." C. Griffin and Co.
Lewes, " Carbonization of Coal." Benn Bros.
Scheithauer, " Shale Oils and Tars." Scott, Greenwood and Co.
P.
PART V.— NATURAL SOLID AND SEMI-
SOLID BITUMENS AND ALLIED
SUBSTANCES
SECTION A.— OCCUREENCE, CHARACTERS,
AND PRODUCTION
NATIVE solid or semi-solid bitumens, pure or associated
with varying quantities of mineral matter, are very widely
distributed, being found in some form or other in most
countries.
The materials included under this head show great
variation in character, not only in respect to their admixture
with mineral matter, but also in the chemical composition
of the bituminous matter.
Asphaltic substances, practically free from mineral matter
are found, and also asphaltic rock, which may be a lime-
stone impregnated with quite small quantities of bituminous
material. They are found also in strata of all geological
ages from the Silurian to the Pleistocene.
lyittle is yet known of the chemistry of these bodies ;
they have really only been studied from the point of view
of solubility in various solvents, and of physical properties
and behaviour when subjected to distillation.
There is little doubt that they are derivatives of
petroleum, formed by the removal of the more volatile
constituents and by gradual transformation of the non-
volatile fractions. There is in many cases definite geological
evidence that such transformation has taken place. Their
frequent occurrence in veins bears out this view.
In consequence of their mode of formation, types
illustrating various stages in the transformation exist ; in
fact, a definite series ranging from ordinary petroleum
residual asphalts such as are made by the concentration of
130
NATURAL ASPHALTS, ETC. 131
certain crude oils, to bodies like albertite which are so
similar in appearance to coal as to have been mistaken for
such, may be distinctly traced.
The differentiation of these bodies into definite classes
is therefore difficult. However, a rough subdivision into
asphalts proper, asphaltites, and asphaltic pyrobitumens
may be adopted.
(a) Asphalts Proper. — These melt below or not far
above 100° C. They are more or less equally soluble, and
almost entirely so in carbon tetrachloride and carbon
bisulphide, and to a large extent also in petroleum spirit of
sp. gr. 0*645. Under this heading are included also the
artificial residual asphalts resulting from the distillation of
asphaltic base crude oils.
(b) Asphaltites. — These have high melting points, a
higher fixed carbon content, are less soluble in carbon
tetrachloride, and still less so in petroleum spirit of
sp. gr. 0-645.
(c) Asphaltic Pyrobitumens.— These are infusible and
are only slightly soluble in carbon tetrachloride, carbon
bisulphide, or petroleum spirit of sp. gr. 0*645.
The asphalts proper are by far the most common.
They are found often in a relatively pure condition, often in
association with mineral matter, and often merely as an
impregnating material.
Relatively pure native asphalts have been found in Cuba,
France, Greece, Mexico, the Philippine Islands, Siberia,
Syria, Venezuela, and in California, Kentucky, and Utah.
Of these deposits one of the largest in the world is that
found in Venezuela, known as the Eermudez asphalt lake.
This covers an area of over 900 acres, and has an average
depth of about 4 feet. It is supplied from various springs
from which the asphalt exudes in a semi-liquid condition,
gradually hardening as it is exposed to the air. Similar
deposits are found on several of the islands in the delta of
the Orinoco, and at Maracaibo. The asphalt is practically
free from mineral matter, but contains much water. The
water, which may amount to as much as 30 per cent., is not
132 PETROLEUM AND ALLIED INDUSTRIES
emulsified, and is easily separated off by heating. Refined
Bermudez asphalt has the following characteristics : —
Fracture . . . . . . . . conchoidal
I^ustre . . . . . . . . very bright
vStreak . . black
Specific gravity at 25° C. . . . . 1*06 to ro8
Penetration at 25° C. . . . . 20 to 30
Ductility . . . . . . . . about n
Melting point (K. and S.) . . . . „ 58° C.
Fixed carbon . . . . . . 13 to 14 per cent.
Solubility in carbon bisulphide . . about 95 ,,
Solubility in 0*645 petroleum ether ,, 65
Volatile matter 7 hours at 163° C. ,, 5
7 hours at 204° C. „ 9
Elementary Analysis —
C . . . . . . 82*9 per cent.
H 10-8
S 5'9 »
N 07
This asphalt contains a considerable percentage of hydro-
carbons volatile below 200° C., differing in this respect
markedly from the other noted natural asphalt supply,
viz. that of Trinidad.
Its soft character is due to the high percentage of
malthenes (soluble in 0*645 petroleum spirit).
The Maracaibo asphalt is similar on the whole to the
Bermudez product possessing the following characteristics : —
Specific gravity at 25*5° C. . . . . 1*062 lo 1*078
Penetration at 25° C. . . . . about 25
Soluble in carbon bisulphide . . 92 to 97 per cent.
Soluble in 0*645 petroleum spirit . . 46 to 54 „
Fixed carbon . . . . 15 to 19 ,
Volatile at 163° C., 7 hours . . . . 1*5 to 5*3 „
Melting point . . . . . . . . about 100° C.
Some samples, however, contain considerable quantities
CHARACTERS OF NATURAL ASPHALTS 133
of vegetable matter. It differs from Bermudez (and
Trinidad) asphalt in having a higher softening point and a
lower percentage of malthenes (soluble in 0-645 petroleum
spirit).
A similar asphalt lake is known on the east coast of the
island of Sakhalin, in Siberia, but this has not yet been
exploited.
The pure asphalt deposits of France, Greece, Syria, and
the Philippine Islands have not yet received much attention.
Native asphalts associated with varying amounts of
mineral matter are also common, many of the deposits being
worked commercially. Occurrences have been noted in
Algeria, Arabia, Argentine, Austria, Canada, Cuba, France,
Germany, Greece, Italy, Japan, Mesopotamia, Mexico,
Portugal, Russia, Sicily, Spain, Switzerland, Syria, Trinidad,
and in the United States, in California, Indiana, Kentucky,
Louisiana, Missouri, Oklahoma, Texas, and Utah.
Of these the Trinidad deposit is the most important.
The main deposit occurs in the form of a lake of about
115 acres in extent, estimated to contain over 9,000,000
tons of asphalt. The asphalt is softer in the centre, where
it seems to be replenished from underground sources. The
consistency is such that it will easily bear the weight of a
man, and it may be easily excavated by means of pickaxes
in the cool of the day. It consists of an emulsion of asphalt,
water, and finely-divided mineral matter. This latter is in
such a fine state of subdivision that it does not separate out
even after the melted asphalt has been kept standing for
many months. The crude asphalt is refined by heating to
1 60° C. for some time to drive off the water. The dry (so-
called refined) product analyses : —
Fracture . . . . . . . , conchoidal
lustre . . . . . . . . . . dull
Streak . . . . . . . . . . black
Specific gravity 1*40 to 1-45
Penetration at 25° C about 7
Ductility at 25° C. about 2
134 PETROLEUM AND ALLIED INDUSTRIES
Melting point (K. and S.) . . . . about 87° C.
Mineral matter „ 40 per cent.
Solubility in carbon bisulphide . . „ 55 „
Solubility in 0*645 petroleum ether . . „ 34 „
The pure bituminous matter freed from mineral matter
analyses : —
Melting point (K. and S.) . . . . about 55° C.
Fixed carbon .. .. . .. .. ,,12
Soluble in carbon bisulphide . . . . 100 per cent.
Soluble in 0*645 petroleum ether . . about 60 per cent.
Elementary Analysis —
C 82*3 per cent.
H 107 „
S 6*2 „
N 0-8 „
As far back as 1883, 35,000 tons of Trinidad asphalt were
imported into the United States, and in 1892 the Bermudez
product appeared on the scene.
The production of asphalt in Trinidad amounted to over
74,000 tons in 1918, but in 1913 the amount was over
230,000 tons. Of recent years, however, the production of
asphalt from Mexican and other petroleums has advanced
with great strides, so that at the present day the actual
amount of asphalt from the Trinidad lake, imported into
the United States, constitutes less than 5 per cent, of the
total consumption of that country (Hubbard, Chemical Age,
New York, 1921, p. 331).
Many native asphalts are found in Cuba; the deposits
are small, but considerable quantities have been exported.
With the exception of the above-mentioned cases,
practically all the important natural asphalt deposits take
the form of a rock impregnated with varying quantities of
asphalt, often not more than 5 to 10 per cent.
The chief deposits worked are found in Ragusa, in
Sicily, Seyssel in France, Jammer in Hanover, and Val de
Travers in Switzerland.
CHARACTERS OF NATURAL ASPHALTS 135
The Ragusa deposits, which yielded about 100,000 tons per
annum, vary in quality, some specimens containing as much
as 30 per cent, of asphalt, the usual percentage being, how-
ever, about 9. The Seyssel deposits contain about 8 per cent.,
Val de Travers about 10, and the I/immer about 14 per cent.
These asphalt rocks find application particularly for
compressed asphalt pavements. For such work, the mineral
constituents should consist, as far as possible, of carbonates
of calcium and magnesium. Asphalt rocks containing
appreciable quantities of silica do not prove so suitable.
Enormous deposits of an asphalt-impregnated sand, the
(wrongly) so-called tar-sands of Athabasca exist in Alberta.
The bituminous material from these sands has recently been
examined by Krieble and Seyer (J.A.C.S., 1921, p. 1337).
They find the asphalt to make up from 7 to 20 per cent, of
the sand.
It is soluble in carbon bisulphide . . 100 per cent.
„ „ petroleum ether . . 86*9 „
These deposits have, however, not yet been exploited.
The natural asphalt rocks of the United States, though
often used locally, have not found favour in comparison with
artificial mastics made from petroleum residual asphalts.
The asphaltites fall into three groups : The gilsonites,
the glance pitches, and the grahamites, which differ from
each other somewhat in fusibility and fixed carbon content,
but the line of demarcation is not distinct, intermediate
products being found.
Gilsonite or uintaite is found only in the United States,
in a belt in the Uinta basin, mostly in Utah, occurring in
vertical veins. The largest of these veins is about 18 feet
in diameter and several miles in length.
About 30,000 tons of gilsonite per year are produced
from this one region. It has the following properties : —
Fracture . . . . . . . . . . conchoidal
Lustre very bright
Streak ' . . . . . . . . . . brown
Specific gravity at 25° C. . . . . ro to n
136 PETROLEUM AND ALLIED INDUSTRIES
Penetration 25° C nil
Ductility 25° C. nil
Melting point (K. and S.) . . . . 120 to 180° C.
Fixed carbon . . . . . . . . 10 to 20 per cent.
Soluble in carbon bisulphide . . over 98 „
Soluble in 0-645 petroleum ether . . 40 to 60 „
Sulphur . . . . . . . . 2
A sample from Syria had the following properties : —
Specific gravity at 15° C. . . . . i'ioi
Fixed carbon . . . . . . -.15 per cent.
Soluble in carbon bisulphide . . . . completely
,, tetrachloride . . . . . . ,,
,, 0*645 petroleum ether . . 28*7 per cent.
Melting point (K. and S.) . . . . 132° C.
The Glance pitches have been found in various localities,
e.g. Mexico, Barbados, Columbia, Egypt, and Palestine.
They resemble gilsonite in many respects, but have a
higher specific gravity 1*10 to 1*15, a black streak instead
of brown, and a higher fixed carbon content ranging from
20 to 30 per cent.
The deposits in Barbados are worked and the product
sold under the name of Barbados manjak. This has the
following properties : —
Colour . . . . . . . . . . black
Fracture . . . . . . . . conchoidal
lustre . . . . . . . . . . bright
Streak black
Specific gravity . . . . . . 1*10
Melting point .. .. .. .. 110° C.
Penetration at 25° C. . . . . . . o
Soluble in carbon bisulphide . . . . over 99 per cent.
,, 0*645 petroleum spirit . . about 27 ,,
Fixed carbon 25 to 30 „
The occurrence of glance pitch has recently been noted
in Australia (North-east Kimberley) Times, October 13, 1921.
CHARACTERS OF ASPHALTITES 137
The grahamites occur in many localities, usually in
small quantities, often associated with mineral matter.
The chief deposits occur in Jackfork Valley, Oklahoma, in
a vein 20 feet thick and i mile in length.
Deposits in Colorado, Cuba, and Trinidad are also worked.
They are lustrous or semi-lustrous, black, with a fracture
sometimes conchoidal, sometimes hackly, and black streak.
Specific gravity at 25° C., .. .. 1*15 to 1*50.
Fusing point ranges from 180° to 130°
C., but melting does not take place as
intumescing occurs on further heating
Fixed carbon high . . ... . . up to 55 per cent.
Solubility in carbon bisulphide over 99 „
„ 0*645 petroleum spirit . . less than i per
cent.
Sulphur . . . . . . . . . . variable up to 8
per cent.
A soft variety, known as Trinidad manjak, is also mined
extensively. Its properties are somewhat similar to those
of Barbados manjak, but its specific gravity is about 1*170,
melting point 180° to 230° C., and fixed carbon 31 to 35 per
cent.
The asphaltic pyrobitumens comprise the elaterites,
albertites, wurtzilites, impsonites, and the asphaltic pyro-
bituminous shales.
These first four classes are sometimes found practically
free from mineral impurity. There is little doubt that these
substances are derived from crude petroleum and represent
the last stages in its transformation. They differ markedly
from the previously described asphaltites in their relative
insolubility in carbon bisulphide.
Elaterite has been found only at Castleton (Derbyshire),
in South Australia, and Siberia (Lake Balkash). It is of
scientific interest only.
It has a brown streak, is of indianibber-like nature, of
specific gravity 0*90 to 1*05. It is insoluble in carbon
disulphide.
138 PETROLEUM AND ALLIED INDUSTRIES
The word elaterite is loosely used in America in place of
wurtzilite.
Wurtzilite is found only in Uinta County, Utah, where it
occurs in veins, as does gilsonite. These veins are generally
less than 3 feet in thickness, but may be a mile or two in
length. About 820 tons were produced in 1917.
It is a hard, lustrous substance, with light-brown
streak, and conchoidal fracture. It can be cut into thin
flakes which are somewhat elastic, rather like mica in this
respect.
Specific gravity . . . . . . . . 1*05 to 1*07
Decomposes before fusing
Fixed carbon . . . . . . . . about 10 per cent.
Soluble in carbon bisulphide . . . . „ „
Practically insoluble in carbon tetra-
chloride and 0-645 petroleum spirits.
Sulphur . . . . . . . . . . about 5 per cent.
It is an example of a thio-kerite, composed chiefly of
kerotenes.
Albertite. — This occurs typically in Albert County, New
Brunswick, where it was mined for many years, being
falsely regarded as a coal. Its mode of occurrence, how-
ever, clearly proves that it is not a coal, as it is found in a
fissure or vein cutting across a series of asphaltic pyro-
bituminous shales. In this particular case there is no
doubt that the asphaltic pyrobituminous shales were formed
by the impregnation of the shales by the same petroleum
which formed the albertite. Both substances, as a matter
of fact, yield the same distillation products.
Albertite has the following properties (Abraham) : —
Specific gravity at 25° C 1*07 to no
Penetration at 25° C. . . . . nil
Ductility . . . . . . . . nil
Melting point . . . . . . intumesces and decom-
poses
Fixed carbon 25 to 50 per cent.
ASPHALTIC PYROBITUMENS 139
Solubility in carbon disulphide . . slight, 2 to 10 per cent.
„ 0-645 petroleum ether „ up to 2 per cent.
„ hot pyridin . . . . about 30 per cent.
Elementary Analysis —
C 83-4 to 87-2
H ...--.• .. . . 9 "2 to 13*2
S .,;•'• .. .. up to i '2
N .. »» „. „ 3-0
O . . , . . . about 2 per cent.
A variety called Tasmanite is found in Tasmania.
Other deposits have been noted in Cuba, Oklahoma, Utah,
and Mexico.
Impsonite, which is found in Arkansas and Oklahoma,
is black and has a semi-dull lustre. Specific gravity at
25° C., 1*125. ^ is infusible and insoluble in carbon bisul-
phide, has a high fixed carbon content (up to 80 per cent.).
A variety from Mesopotamia analysed as follows : —
Specific gravity * . . . . . . . 1*231
Melting point infusible
Fixed carbon . . . . . . . . 44*8 per cent.
Solubility in carbon disulphide. . 10*6 „
,, carbon tetrachloride . . nil
„ 0*645 petroleum ether . . nil
pyridin .. .. ..97
This, apparently the most advanced stage in the trans-
formation of petroleum, differs from the non-asphaltic
pyrobitumins (the coals, etc.) chiefly in its low oxygen
content.
The asphaltic pyrobituminous shales are distinct from
the pyrobituminous shales, in that they are really shales
impregnated with asphaltic pyrobitumens. It is naturally
difficult to differentiate the two types, as the asphaltic
pyrobitumens are so slightly soluble in solvents. The
percentage of oxygen in the asphaltic pyrobituminous shales
is low, being below 2 for wurtzilite shales and less than 3
for albertite shales. For non-asphaltic shales it varies from
140 PETROLEUM AND ALLIED INDUSTRIES
3 to 28 (Abrahams, " Asphalts and Allied Substances,"
p. 159). Moreover, on treating in a closed retort to 300°
to 400° C. the asphaltic pyrobituminous shales will depoly-
merize and become more soluble in carbon bisulphide ; the
non-asphaltic shales do not do so.
The non-asphaltic pyrobituminous shales have apparently
been derived from the decomposition of vegetable matter
in a manner similar to that by which coal was formed.
These two types of substances, moreover, differ in respect
to the products yielded by destructive distillation. The
asphalts, asphaltites, and asphaltic pyrobitumens yield
usually open chain hydrocarbons, the non-asphaltic pyro-
bitumens, chiefly cyclic hydrocarbons. The properties of
the asphalts, asphaltites, and asphaltic pyrobitumens may
be most readily compared by means of the following table : —
Fixed
Sol. in
Soluble
Sul-
Sp. gr.
M. pt.
carbon
%.
0-645 pet.
ether %.
inCSp
%.2
phur.
Asphalt manufactured from j
Mexican petroleums . . J
I -06
57°C.
*4
60
100
5
Trinidad lake asphalt, free}
from mineral matter /
I 065
55
12
63
100
7
Gilsonite . .
I'll
120/180
10/20
40/60
IOO
2
Glance pitch
I-I5
I2O
25/30
25
IOO
8
Grahamite . .
Wurtzilite . .
I'3 }
I -06
Intumesce
with
55
10
traces
nil
IOO
10
8
5
Albertite . .
I-I
decompo-
4°
nil
5
i
Impsonite . .
I'2 J
sition.
80
nil
nil
—
The above figures are approximate only, being given merely for
purposes of comparison.
It will be realized from a consideration of the above
that the chemical nature of the asphaltites and asphaltic
pyrobitumens is very far from being understood. The
means of discrimination between the various classes of the
series are inadequate and empirical, many intermediate
varieties being known. There are however, undoubtedly,
grounds for the presumption that these substances are
petroleum derivatives and that they form a series repre-
senting stages in its transformation.
ASPHALTIC PYROBITUMENS
141
Richardson (J. Ind. and Eng. Chem., vol. 8, p. 493) gives
data from the analyses of a number of gilsonites and
grahamites which bear out this view, and demonstrate that
the changes which particular types of petroleum undergo in
nature depend on the environment.
Flow-point °F.
Sp. gr.
Per cent,
soluble in 0*64 5
petroleum
spirit.
Per cent,
fixed
carbon.
GILSONITES—
Utah softest
285
I -01 1
55'5
lO'O
» »»
1-037
46-9
I2'3
*
260
—
47-2
12-8
it
345
1-037
46-I
I3'9
,, hardest
intumesces
i '05 7
24-5
16-7
G RAHAMITES
Cuba Bahia
intumesces
I-I57
38-8
40-0
Trinidad
tt
1-156
14-8
40-0
W. Virginia
tt
1-130
9*4
36-8
Colorado
1-160
0-8
47H
Oklahoma
••
1-184
0-4
5IH
The occurrence of a material intermediate in character
between asphalt and gilsonite in the central valley of
California at Asphalto further confirms this idea.
The development of this extremely interesting question
will entail much patient research.
A considerable industry connected with the native
asphalts has developed in the United States. In 1919 the
production reached 88,281 short tons (Cottrel, "Asphalt
and Related Bitumens," "Mineral Resources of the United
States/' 1919, p. 279). Of this amount 53,589 was rock
asphalt, the balance being made up of gilsonite, grahamite,
wurtzilite, and impsonite (Hubbard, Chemical Age, New
York, 1921, p. 331).
GENERAL REFERENCES TO PART V., SECTION A.
Abraham, " Asphalts and Allied Substances." D. van Nostrand Co.
Danby, " Natural Rock Asphalts and Bitumens." Constable and Co.
Ladoo, " The Natural Hydrocarbons," Reports on Investigations,
U.S. Bureau of Mines, 1920.
Peckham, " Solid Bitumens." Myrom Clark Pub. Co.
Richardson, " The Modern Asphalt Pavement." Wiley and Sons.
SECTION B.— APPLICATIONS
THK applications of the natural solid and semi-solid bitumens
are many and varied. Enormous quantities of the rock
asphalts and asphalts proper are used for road-making or
paving purposes, smaller quantities of the asphaltites are
used for many special purposes, while some of the natural
pyrobitumens are little used. Of the mining of these
materials little need be said.
The rock asphalts are quarried according to usual
methods. They are largely used for surfacing roads which
are required to stand very heavy traffic. The broken pieces
of rock asphalt as received from the mine, are passed
through disintegrators and reduced to a fine powder, which
forms the basis of the made-up products. The rock from
the quarries may contain various percentages of asphalt
and so usually requires blending with either mineral matter
or asphalt to obtain a mixture containing the requisite
proportion of asphalt. In many cases a powdered rock
asphalt rich in asphalt, is blended with one poor in asphalt
to obtain the desired result. In other cases the powder is
incorporated with petroleum asphalt, heated, cooled, and
again disintegrated. The asphalt is first melted in a special
mixer and the powdered rock is added and thoroughly
incorporated at a temperature of 200° C. It is then run off
into moulds arranged on a concrete floor and allowed to cool.
The floor and sides of the moulds are previously coated with
whiting or other material to prevent the adhering of the
asphalt. In some cases coal-tar products, or shale-oil
products are used in place of asphalt, but the resulting
product is unsatisfactory. This rock asphalt is applied to
road surfaces by the compressed powder method. A good
142
APPLICATIONS OF NATURAL ASPHALTS, ETC. 143
concrete foundation is essential. The powder must be laid
down on a dry surface in dry weather. The powder is
heated to a temperature varying from 100° to 150° C.,
spread out on the surface of the concrete, raked to the
necessary thickness, and then compressed by tamping with
heated rammers, the surface being finally smoothed off by
heated irons. As a decrease of volume of the heated powder,
to the extent of 40 per cent, takes place on compression, allow-
ance for this must be made when laying down the powder.
This method of road-making is to some extent being
superseded by rock asphalt tiling. Tiles of about a square
foot in area are made in the factory, being subjected to
compression in hydraulic presses. A more uniform and
denser material is thus assured. The tiles are easily laid,
the edges being sealed by dipping in melted asphalt.
A rock asphalt surface stands up very well to heavy
vehicular traffic, the constant heavy pressure keeping the
material in good condition. The natural asphalts of Trinidad
and Berrnudez are also largely used for road work. In the
case of the Trinidad lake the crude asphalt is obtained by a
quarrying process, as the asphalt is sufficiently hard to
allow of its being broken up by pickaxes, except in the
hottest part of the day. A movable decauville track is laid
down on sleepers on the surface of the lake, the surface
being sufficiently hard to allow of this temporarily.
The asphalt as mined from the Trinidad lake contains
about 50 per cent, of its bulk of water, decaj^ed wood, and
vegetable matter. The impure product is heated for some
hours in large cauldrons, the temperature being finally
raised to 160° C. The vegetable refuse which floats to the
top is skimmed off, and the molten asphalt is then drawn
off leaving the excess of solid mineral matter at the bottom
of the cauldron. The so made " Trinidad epure " is then,
however, far from pure. vSuch a crude method of refining
undoubtedly harms the product, as the portions of the
asphalt near the sides of the cauldron must often be over-
heated. The material is more satisfactorily treated by
superheated steam, avoiding the use of direct fires. Trinidad
144 PETROLEUM AND ALLIED INDUSTRIES
asphalt cannot, however, be purified completely in this way.
About 35 per cent, of exceedingly finely divided mineral
matter is obstinately retained emulsified in the asphalt.
The marketed product always contains this mineral matter.
The pure bituminous material could only be obtained by
means of extraction by solvents. This is, however, un-
necessary as the bulk of the Trinidad asphalt is used for
road-making, for which purpose it must in any case be
mixed with mineral " fillers." The water and mineral
matter associated with Bermudez asphalt separates out
much more easily.
By far the most important application of the Trinidad
and Bermudez asphalts is that of road-making. For the
same purpose, too, the asphalts made from certain crude
petroleums, notably those of Mexico, are used to a very
great extent, and the application for road-making purposes
of both types may well be considered together.
The asphalts made from crude oil possess one great
advantage in that they can be made of any desired con-
sistency simply by varying the extent to which the crude
oil is concentrated down in the process of manufacture.
The naturally occurring asphalts are more or less of
constant composition, too hard for certain classes of work.
They therefore require to be " cut-back " or ' 'fluxed " with
less viscous oils in order to give products of the required
consistency.
The consistency of an asphalt for road-making purposes
may be judged by the " penetrometer." This is an instru-
ment which records in tenths of a millimetre the distance to
which a standard No. 2 sewing needle, loaded with a weight
of 100 grams, will sink into the asphalt at a temperature of
77° F. (25° C.) in five seconds. This is known as the
" penetration."
The types of asphalts used for road work have penetra-
tions varying from 40 to 200, according to the class of work.
The penetration of Trinidad lake asphalt is only about 7
owing to the high content of mineral matter, that of the
Bermudez product being about 25.
APPLICATIONS OF NATURAL ASPHALTS, ETC. 145
Apart from " compressed asphalt paving " as described
above, there are, broadly speaking, three systems of road
construction involving the use of asphalt.
They are : (i) Asphalt carpet ; (2) Asphalt macadam ;
(3) Grouting or penetration work.
For asphalt carpeting work the asphalt is mixed with
definite proportions of sand, stone (or clinkers, etc.) and
filler, all carefully graded to specification. The mixture is
spread hot on the road and carefully rolled. Such carpets
may be laid down on cement or on a previously existing
macadam surface.
In many cases two-coat work may be carried out, a
sub-coat of 3 inches or more of a coarse asphaltic concrete
being laid down and consolidated, a i-J-inch carpet, made
of more finely graded material being laid down on top. The
material used should be graded so that a voidless matrix
may be obtained.
For asphalt macadam work the macadam is heated in a
mixer with sufficient asphalt to coat the aggregate completely.
The mixture is then carted into position while still warm,
laid down and rolled.
For grouting or penetration work an asphalt of softer
quality may be used. The aggregate suitably graded is
laid down and rolled and the hot asphalt is poured over, or
sprayed on by a special machine, at the rate of about
ij gallons to the square yard. The surface is then lightly
covered with dry chippings and the road is then well rolled.
A sealing coat of asphalt is then applied and a final dressing
of chippings. Dryness is essential to the making of a good
asphalt road.
As a road binder petroleum asphalt is superior to coal
tar in many respects. For example, coal tar contains
water soluble constituents, also volatile constituents such as
naphthalene. Moreover, it is difficult to obtain coal tar of
uniform composition, and the gradual introduction of vertical
retorts and of carbonization at lower temperatures is bring-
ing about the production of tars less suitable for road work
than those produced by carbonization in horizontal retorts,
p. 10
146 PETROLEUM AND ALLIED INDUSTRIES
The subject of road-making is, however, beyond the
scope of this work, so for further details the reader must be
referred to any of the many books now published dealing
with this subject.
The other uses of natural asphalts will be described in
the section dealing with petroleum asphalts.
The natural asphaltites which occur in veins are generally
mined by crude methods. The largest known vein of
grahamite, namely that at Jackford Creek, in Oklahoma,
where the asphaltite fills a fault in sandstone, is mined by
means of inclined shafts, in a manner similar to that used
in Scotland for shales.
The natural asphaltites are often employed just as
mined. Should, however, they be mixed with adhering
mineral matter, they may be refined by merely melting off.
Gilsonite is used principally in the manufacture of
paints, japans, and varnishes. Its value in this respect is
enhanced by the fact that it is easily miscible with fatty
acid pitches (grahamite is not) .
Such bituminous paints are made from a variety of
substances such as natural asphaltites, petroleum asphalts,
blown asphalts, various tars and pitches, montan wax,
fatty oils and acids, and various resins, together with
various mineral fillers, incorporated with various solvents
such as benzine, kerosene, turpentine, resin oils, coal-tar
products, carbon tetrachloride, alcohols, acetones, etc.
Gilsonite is also largely used in the rubber industry for
incorporation into motor-car tyres, as a vulcanized mixture
of rubber and gilsonite is much more resistant to oxidation
and changes of temperature than is rubber alone.
Grahamite is also used in the manufacture of varnishes,
rubber substitutes, insulating material, as is also manjak.
Wurtzilite is used for the manufacture of the so-called
wurtzilite asphalt or pitch, commercially known as " kapak."
This is made by heating wurtzilite to about 300° C. under
pressure. Decomposition sets in and oils are evolved which
are condensed and returned to the vessel. The mass is thus
converted into a fusible substance differing from the original
APPLICATIONS OF NATURAL ASPHALTS, ETC. 147
wurtzilite in being soluble in carbon bisulphide and 0-645
petroleum spirit. This kapak is used for manufacture of
varnishes, insulating material, and for weatherproof coatings,
etc.
GENERAL REFERENCES TO PART V., SECTION B.
Baker, " Roads and Pavements." J. Wiley and Son.
Blanchard, " American Highway Engineers Handbook." J. Wiley and
Son.
Boulnois, " Modern Roads." Arnold.
Hubbard, " Dust Preventives and Road Binders." J. Wiley and Son.
Kohler und Graefe, " Natiirliche und Kiinstliche Asphalte." Vieweg
und Sohn.
Tillson, " Street Pavements and Paving Materials." J. Wiley and Son.
PART VI.— THE NATURAL MINERAL
WAXES
UNDER this heading may be described the two substances
ozokerite and montan wax, the former of which is found
native, the latter extracted from certain lignites by a solvent.
These two substances differ fundamentally in character,
both from each other and from the asphaltic substances
dealt with in the last part.
Ozokerite is a naturally occurring hydrocarbon sub-
stance. It is known also as mineral wax, rock tallow,
mineral adipocere, citricite (in Moldavia), nestegil (Caspian
area), and baikerite (Siberia).
It is composed of hydrocarbons of higher melting point
than those constituting the paraffin waxes. It is usually
found associated with petroleum and often contains an
admixture of paraffin wax, in which cases the melting point
is lower. Such mixtures, intermediate in character between
pure ozokerite and paraffin wax, are known as " kindebal."
It is usually found in fissures or veins, irregular in
character. It has in all probability entered these veins
from below, and is a derivative of paraffinaceous petroleum.
A product known as rod-wax, often found clogging up the
pumps in paraffin wax-base oil wells, is similar to ozokerite
in nature.
It is found chiefly in Galicia, the largest deposits being
in the Boryslaw area ; also in Moldavia (Rumania), and in
Cheleken in the Caspian Sea (Petroleum World, 1917,
p. 136).
In the United States it has been found in Utah (Higgins,
Salt Lake Min. Rev., 1916, p. 17). It is a waxy substance
varying in colour from yellow through brown to black,
according to the impurities present. It varies in con-
148
THE NATURAL MINERAL WAXES 149
sistency, sometimes having a conchoidal fracture, sometimes
being quite soft. Its specific gravity varies from 0*85 to
i -oo, melting point from 60 to 90° C. Its fixed carbon
value ranges up to 10 per cent. If pure it is completely
soluble in carbon bisulphide and in 0*645 petroleum ether.
The elementary analysis of the purified hydrocarbon product
is C. 85 per cent., H. 15 per cent. It can be distilled in high
vacuum without decomposition, but at ordinary pressures
it decomposes yielding oils, paraffin wax, and an asphaltic
residue. The total output does not amount to more than a
few hundred tons per year.
Ozokerit is mined by the normal methods applicable to
any such substance, a mixture of ozokerit and gangue or
associated mineral contamination being raised to the surface.
The mixture is then separated by hand picking. Those
portions which consist of lumps of rock with small quantities
of ozokerit adhering or enclosed are boiled up with water,
and the wax which rises to the surface is separated off.
The wax so obtained, together with the picked wax, is
then melted, care being taken to keep the temperature as
low as possible, the molten wax free from mineral impurities
being drawn off from the surface and cast into moulds.
Ozokerit is usually refined, the resulting product being
termed Ceresin.
The dried and melted ozokerit is heated with a few
per cent, of fuming sulphuric acid, with adequate mixing,
at a temperature of about 120° C., the process being repeated
as often as necessary in order to obtain a colourless
product, a considerable quantity of acid tar being formed.
Alternately, instead of allowing the acid tar to settle, the
whole mass is heated up to from 160° to 200° C. An
energetic oxidation sets in, with copious evolution of sulphur
dioxide. The temperature is maintained at 200° C. until
all the free acid has been expelled. If a little free acid still
remain this may be neutralized by an alkaline fuller's-earth
added in the air-dry condition to the ceresin at a temperature
of about 150° C. After settling the wax is drawn off and
treated with a decolorizing powder, the carbonaceous residue
150 PETROLEUM AND ALLIED INDUSTRIES
from the manufacture of ferrocyanides being usually used.
Separation of the wax from the decolorizing powder is
effected by filter pressing.
The refined ozokerit or ceresin is amorphous in character,
resembling beeswax in character. Its specific gravity is
about 0*920. Melting point 60 to 90° C. Owing to its high
melting point and its miscibility with vegetable and animal
fats and oils it is a valuable product, commanding a much
higher price than does paraffin wax, with which it is conse-
quently often adulterated. The question of the identification
of paraffin wax in ceresin is therefore of importance.
As mixtures of ceresin and paraffin have no well-defined
melting point, a series of fractions may be obtained by
carefully cooling the mixture. The examination of the
melting points of these fractions will disclose the presence
of paraffin (Berlinerblau, " Das Erdwachs," 1897, p. 195).
The other adulterants, e.g. saponifiable fats, resins, etc., are
more easily detected, as the determination of the saponifi-
cation value will at once indicate their presence. For details
of these methods reference should be made to one of the
standard works such as Holde, " Examination of Hydro-
carbon Oils, etc."
Ceresin is largely used for making candles, its hardness
and high melting point rendering it superior to paraffin in
this respect. It is largely used in the manufacture of
polishes, waterproofing, and insulating materials, of sealing
waxes, leather- treating greases, and so forth ; also as a basis
for pomades and ointments, and for modelling waxes,
gramophone records, and many such kindred uses.
Montan Wax. — A product of an entirely different
nature which may be described here is that known as
" Montan wax." This interesting substance is obtained from
certain Thuringian and Bohemian lignites, and the peculiar
lignite known as pyropissite. These lignites by extraction
with solvents such as benzol yield montan wax ; on distilla-
tion in the usual manner they yield oils rich in paraffin
wax (p. 127). Pyropissite as brought to the surface is a
lightish yellow, earthy-looking substance, containing much
THE NATURAL MINERAL WAXES 151
water, which, however, readily dries off on exposure to the
air. Supplies of this mineral are now however rapidly
nearing exhaustion.
If pyropissite be extracted with various solvents a
bituminous product similar to ozokerite in appearance is
obtained, the nature dependent to some extent on the
solvent used. This bituminous product, however, is very
difficult to refine to a white product, except by using more
than an equal weight of oleum, followed by decolorizing
powder and subsequent extraction of the mass by benzine.
Boy en found that this bituminous product could be distilled
with steam, yielding a pale yellowish, crystalline body with
a high melting point (over 70° C.). This method forms the
basis of the manufacturing process now adopted. The raw
bituminous material which is the starting point for the
manufacture of montan wax, is obtained from the lignite
either by extraction or by distillation in presence of much
superheated steam in cylindrical retorts. The distillate so
obtained differs from the distillate obtained by distilling at
higher temperatures with less steam, the latter containing
much paraffin wax.
This bituminous product, or the product obtained by
extraction of the liquid with benzol, is then subjected to
several distillations in vacuo with the aid of superheated
steam. The mineral wax so obtained is subsequently
refined in a normal way, by treating it in benzol solution
with decolorizing powders, the benzol being subsequently
distilled off. The montan wax so obtained is a faintly
yellow-tinted, hard crystalline substance, somewhat like
stearin in appearance, possessing a faint, pleasant, aromatic
odour. The specific gravity varies from 0*9 to 1*0 ; the
melting point from 80° to 90° C. It contains 82 to 83-5 per
cent, carbon, 14 to 14-5 per cent, hydrogen, 3 to 6 per cent,
oxygen, and traces of sulphur and nitrogen (Marcusson,
Chem. Rev. Fett-Harz. Ind.t 1908, p. 143).
Montan wax differs fundamentally from paraffin wax in
that it is composed of a mixture of an acid (montanic) of
high molecular weight, with esters of an alcohol of high
152 PETROLEUM AND ALLIED INDUSTRIES
molecular weight. This montanic acid has a melting point
of 83° to 84° C. Tetracosanol, ceryl alcohol, and myricyl
alcohol have been identified in montan wax by Pschorr and
Pfaff (Ber., 1920, p. 2147) . Montan wax is used in admixture
with paraffin wax for candle-making, in making substitutes
for the valuable carnauba wax, for insulating materials,
polishes, and many other such purposes. Owing to its high
melting point as compared with paraffin wax, it commands
a higher price.
GENERAL REFERENCES TO PART VI.
Berlinerblau, " Das Erdwachs." Vieweg tmd Sohn.
Graeie, " Braunkohlenteer Industrie." Halle.
Gregorius, " Mineral Waxes." Scott, Greenwood and Co.
PART VIL— THE WORKING UP OF
CRUDE OILS
SECTION A.— DISTILLATION OF CRUDE OIL
IN few cases only does crude petroleum issue from the
wells in a condition ready for marketing, the content of
volatile fractions, which may be low, being usually sufficient
to cause the flash-point of the crude to be below 150° F., the
value usually accepted as the low limit for commercial fuel.
Certain heavy crudes have, however, flash-points higher than
this figure, and such crudes may be marketed directly as
liquid fuels, provided that they are free from admixed water
and have not too high setting points or viscosities.
In the majority of cases, however, crude oils require
treatment in order to remove volatile constituents, valuable
lubricating oil or wax fractions, or asphalt, as the case
may be.
The actual detailed treatment necessary for any particular
crude will depend on (a) the nature of the crude, (b) the
market value and cost of extraction of the various products
it contains.
The method of general application for the working up
of crude oils is that of distillation under various conditions,
refrigeration, filtration, and chemical treatment being also
applied for certain purposes. As crude oils are com-
posed of a complex mixture of substances of varying
boiling points, a rough separation only into fractions of
narrower boiling point ranges may be effected by simple
distillation.
Distillation may be carried out in various ways, in
many different types of plant and with very varying
results.
153
154 PETROLEUM AND ALLIED INDUSTRIES
The methods usually adopted may be divided into —
(1) Distillation at atmospheric pressure.
(2) ,, under vacuum.
% (3) „ underpressure.
It is superfluous "to explain here that the boiling point
of a liquid depends on the pressure. As the constituents
of petroleum of relatively high boiling points are unstable
at high temperatures, i.e. begin to " crack " or split up into
hydrocarbons of lower molecular weight, usually with
separation of carbon and sometimes hydrogen, the method
of distillation employed will be that which enables the
boiling points to be lowered or raised according as cracking
is to be avoided or effected. For example, the distillation
of lubricating oils, in which case the presence of cracked
products is undesirable, may be conducted under vacuum,
whereas when the production of cracked products, as motor
spirits, is desired, distillation under pressure may be employed.
On account of its relative simplicity, distillation under
atmospheric pressure is, as far as possible, the usual practice.
This is usually, however, modified by the introduction of
live steam into the oil during distillation, a method which
to some extent gives the advantages of distillation under
reduced pressure, owing to the lowering of the partial
pressure of the oil by the admixture with steam.
Distillation with steam consequently yields distillates of
higher flash-point, of better colour, and of higher viscosity
than does the so-called dry distillation of the same oil.
Further, in the case of distilling a paraffin wax crude
oil, fractions of higher melting point, but less easily crystalliz-
able, are obtained than when distilling without steam.
The subject of fractional distillation is fully treated in
Young's book, " Fractional Distillation," Macmillan and Co.
Methods of distillation may be further classified under
two main headings : (a) periodic, and (b) continuous.
Periodic methods were naturally those first employed.
They are still largely employed for certain purposes, particu-
larly where the residue requires to be brought carefully to
a certain specification, and, of course, in those cases where
DISTILLATION OF CRUDE OIL
155
the residue is a solid coke. Continuous methods offer many
advantages which will be discussed later and are now in
general use.
Periodic Distillation of Crude Oil at Atmospheric
Pressure. — Periodic distillation at ordinary pressures is
usually carried out in steel stills of cylindrical shape.
These stills may be of large capacity, usually of from
30 to 50 tons, but often much larger. They are constructed
of steel plates riveted together, the bottoms, when possible,
being made of one piece.
5
FIG. 17. — Diagrammatic view of crude oil still.
Each still is provided with the following fittings : —
1. One or more domes, to which are connected
2. The vapour line.
3. A trap in the vapour line to return to the still any
spray of oil mechanically carried over.
4. One or more manholes,
5. A filling pipe.
6. A draw-off pipe, with
7. Internal valve.
8. A perforated steam pipe.
9. Gauge glasses.
10. Thermometer.
11. Vacuum and pressure gauge.
156 PETROLEUM AND ALLIED INDUSTRIES
I/arge stills, particularly those used for lubricating oil
and asphalt manufacture, are fitted with two or three domes.
The vapour line is usually 6 or 8 inches diameter for small
stills, but of 12 or 15 inches, or larger for the larger sizes.
The trap in the vapour line, an important item too often
omitted, may be fitted with perforated baffle plates. The
effect of this in retaining and returning to the still particles
of black oil mechanically carried over is very marked.
Without it distillates of poorer colour are obtained.
The draw-off pipe should always be made of cast steel.
One or more perforated pipes for the introduction of live
steam are distributed over the bottom of the still, placed
an inch or so above the bottom, with the perforations pointing
downwards and outwards. One or more gauge glasses
should be fitted, which should preferably be placed a little
distance from the still. Sample cocks may also be fitted
and are sometimes used instead of gauge glasses. Floats
of various designs are also often employed to indicate the
level of the oil in the still. Some form of thermometer is a
very necessary adjunct.
Stills are often fitted with internal fire tubes, just as are
Cornish boilers, the heating surface being thus considerably
increased. Such fire tubes are usually placed a little to
one side of the vertical diameter of the still, in order to
assist in the circulation of the oil, but such fire-tube stills
cannot be used for periodic work, as the reduction in volume
of the crude would cause the level to fall below the top
of the fire tube. Stills of elliptical cross section are also
sometimes employed. The type and dimensions of the still
to be employed depends to a large extent on the nature of
the work which it is called upon to do. Obviously a still
constructed to stand the conditions necessary for the distilling
off of volatile fractions, will not stand up to the heavy work
of distilling down to a solid residual coke. Stills for work
of this type must be specially constructed with heavy
riveting, with bottoms made of as few plates as possible,
preferably a single plate if the size of the still allows it.
The still is mounted in a brickwork setting with a slight
DISTILLATION OF CRUDE OIL 157
fall (an inch or two) towards the draw-off end. The setting
is usually arranged so that the furnace gases after passing
along the bottom of the still return along the sides. Dampers
are arranged so that, as the volume of the oil in the still
diminishes, the side flues can be cut out and the furnace
gases passed directly to the chimney. One square metre
of heating surface is usually allowed for one ton of distillate
per 24 hours.
The vapour pipe leads, in the simplest types of plant,
direct to the coolers, but as a general rule some form of
FIG. 1 8. — Cast-iron box condenser.
fractional condensing plant is interposed. The coolers or
condensers consist essentially of a system of pipes cooled
by water in which the vapours are condensed and cooled.
The question of design of condensers depend upon various
factors, such as the availability of water supply, and whether
this is fresh or salt, the presence or otherwise of corrosive
vapours in the oil distillates, and the question of economy
and conservation of heat. The obvious method of effecting
this is the use of crude oil as a condensing agent instead of
water. This modification is often employed in continuous
plant, but as its application to periodic plant is not so simple,
water condensing is usually adopted.
158 PETROLEUM AND ALLIED INDUSTRIES
The simplest form of condenser consists of a series of
cast-iron pipes of diminishing diameter, placed in a cast-iron
box (Fig. 18). The vapours enter at the top and descend,
issuing at the bottom as condensed distillate.
It is usual to attach a gas vent to the outflow pipe in
order to allow any uncondensed gases to escape.
The condensing surface necessary depends on many
conditions, the thickness of the tubes, temperature of the
distillate to be condensed, condensing water, and so forth.
As the efficiency of the condenser depends largely on the
degree of cleanliness of the surfaces of the pipes, it is well
to allow ample margin. For light distillates a cooling
surface of 70 square metres per ton of distillate per hour
is usually considered ample.
It must, however, be borne in mind that relatively large
quantities of steam are employed, and must be condensed
during the distilling over of the higher boiling-point fractions,
so allowance must be made for the condenser to deal with
this, although in the case of fractions which are not volatile,
cooling of the distillates to atmospheric temperature is not
necessary.
Many other forms of condenser are employed in the
petroleum industry, the steel tubular type, similar to the
boiler of a locomotive engine being very common. A recent
innovation of very high efficiency is the multiwhorl cooler.
In this form the vapours are condensed in a nest of parallel
tubes placed vertically, round which the ascending stream
of water (or crude oil) is made to ascend spirally by suitable
baffle plates. The heat exchange is consequently very good
and the efficiency high. The description of the many forms
of condenser in use is, however, beyond the scope of this
book.
When crude oil is distilled on the periodic system, the
following method of working is adopted. The crude oil is
filled into the still (to about two-thirds full), which is then
gradually heated. A volatile crude will even begin to distil
before its temperature rises to 100° C. In the case of crude
oils which are thick and heavy and contain water, much care
DISTILLATION OF CRUDE OIL 159
must be exercised to avoid the contents of the still foaming
over when 100° C. is passed. Such crudes are, however, best
distilled by one of the continuous methods described later.
The temperature of the crude oil is gradually raised
up to about 125° C., and then small quantities of steam
(preferably superheated) are admitted by means of the
perforated steam coil. The rate of distillation will be at
once increased, and will continue at temperatures as much as
50 degrees lower than if no steam were admitted. When
the specific gravity of the distillate reaches a certain figure,
which depends on the nature of the crude, and which has
been determined by laboratory tests, a cut is made, i.e. the
distillate is run into another receiving tank.
The first fraction taken may in some cases yield a product
of boiling-point range (when examined in an Engler flask)
suitable for benzine or motor spirit, a product boiling up to
say 220° C. The next distillates will be a mixture of benzine
and kerosene, the point at which the cut is made depending
again on laboratory tests. A point will then be reached
when the boiling-point range and flash-point of the fraction
allows this to go into the kerosene fraction, and the distilla-
tion will be continued until the colour or boiling points of
the fractions indicate the necessity of a change.
The next fraction will, in most cases, be a gas oil, but
the higher fractions will depend on the nature of the crude.
At this point the distillation is often stopped, as the residue
in the still is considerably reduced in bulk. This residue is
run off through a cooler into a separate tank or, better, filled
direct hot into another still for further distillation.
In the case of a paraffin-wax-containing crude, the
further distillation carried out with ample supply of steam
will yield wax distillates. When the wax distillates (which
contain lubricating oil) have been distilled off, the residue
may be, in the case of certain crudes, e.g. those of Pennsyl-
vania, a steam-refined cylinder oil. In other cases a wax-free
residue is not obtained, so that the distillation may be
carried on further, yielding wax tailings and eventually
petroleum coke.
i6o PETROLEUM AND ALLIED INDUSTRIES
In the case of asphaltic oils the distillation may be
carried on so as to give lubricating oil distillates and a
residual asphalt of varying properties according to require-
ments. Such a periodic distillation of crude oil may also
be carried out without the introduction of steam. In this
case the distilling temperatures are higher and a certain
amount of decomposition or cracking takes place, resulting
in a higher }deld of benzine and kerosene fractions. When
crude oils are distilled down to asphalt of a particular
specification, ample steam is used to avoid cracking as far
as possible, but when they are distilled down to coke, steam
is not employed, so that the distillates obtained may be thin
and relatively volatile oils.
A distillation carried out in a simple plant, as above
described, is naturally far from complete. Well-defined
fractions cannot be obtained ; for example, no clear cut
between benzine and kerosene can be made, a large inter-
mediate fraction being obtained. The larger these inter-
mediate fractions, the more redistillation is necessary.
In order to diminish the yield of such intermediate
fractions, fractional condensers, towers, or dephlegmators as
they are often incorrectly termed, are introduced into the
vapour line before the condensers. These fractional con-
densers behave to some extent as fractionating columns.
It would be difficult to fit an efficient form of fractionating
column to a periodic crude oil still, owing to the large range
of distillates to be handled in one run. These towers
or dephlegmators are of more simple construction, but do
considerably improve the separation of the fractions and
obviate the necessity for much redistillation.
In some cases a series of vertical pipes, the bottom bends
of which are connected to run off pipes passing through a
cooler are used. As the vapours pass through these pipes,
the higher boiling portions condense first, so a series of
condensates of increasing volatility are drawn off from the
successive vertical pipes. A similar series of large diameter
pipes laid horizontally is also used in lubricating-oil distilling
plants.
DISTILLATION OF CRUDE OIL
161
Other types, consisting of vertical cylindrical vessels
fitted with various forms of baffle plates and sometimes with
water-cooling coils, are often employed.
An example from actual practice will illustrate the
effectiveness of such an arrangement. A still fitted with two
cylindrical dephlegmators, each containing a series of baffle
plates arranged alternately and fitted with a small water
coil, yielded three separate condensates, one running from
the bottom of each dephlegmator, the third running from
the end of the main condenser. Samples of these three
condensates taken simultaneously gave the following results
on distillation in a standard Bngler flask : —
Percentage boiling up to
Fraction from
Sp. gr.
@i5°C.
200° C.
225°C.
250° C.
275° C.
300° C.
Dephlegmator I
0-836
_
_
5
21
52
II ..
0-830
—
5
18
47
80
Main condenser
0-816
7
24
57
80
94
These three condensates show considerable difference
in properties ; that from the main condenser could just go
into kerosene distillate direct, the other two could not ;
that from dephlegmator II would be worth redistilling for
kerosene ; that from dephlegmator I might not. If all three
had been collected together, the whole fraction would have
required redistillation.
A type of tower largely used in the United States (Fig.
19) is made up of three or more sections, each consisting of
a series of tubes A expanded into tube plates, exposed to
atmospheric cooling ; between each nest of tubes is a closed
chamber which contains a trough B which collects the
condensates from the tubes and delivers them to coolers
outside the tower. The vapours rise through the tower and
partially condense, yielding several condensates of necessarily
increasing volatility as the vapours pass through the system,
which often consists of several such towers in series. The
uncondensed vapours from the top of the last tower pass on
to a water-cooled condenser.
P, ii
162 PETROLEUM AND ALLIED INDUSTRIES
The condensates from the towers may, if necessary, be led
back to the still. This is usual when distilling certain types
of oil, when cracking is necessary.
The actual method of distilling
a crude oil depends to such an
extent on the nature of the crude
and of the products desired, that
any detailed description for a par-
ticular crude would be of little
value. The method of distillation
settled upon must be decided by
careful laboratory analyses of the
fractions obtained. Consideration
of the boiling-point ranges, specific
FIG. I9.-Fractionating tower. S^itieS, flash-points, cold tests,
viscosities and colours of the dis-
tillates will determine their distribution into various frac-
tions. The distillates after cooling are led by separate
pipes to the " tail- or separating-house," where they are
collected in separate compartments of a special tail-box,
or run by means of adjusting valves in a manifold to
separate tanks.
The actual control in the tail-house is usually effected
by the determination of the specific gravity of the dis-
tillate, laboratory determinations having previously indicated
the properties of the fractions of particular specific gravities.
It will be readily understood that the process of periodic
distillation as above described cannot be the most economic
possible. The plant is not fully occupied, as time is lost in
filling and emptying the still. Much heat is also lost in
alternately heating and cooling the brickwork setting, a pro-
cess which does not tend to increase its life. The waste heat
of the hot residue cannot be easily utilized owing to its
intermittent production ; moreover, one single plant cannot
be well designed to handle such different distillates as light
benzine and heavy gas oil or wax distillate. These and other
considerations have brought about the development of —
Continuous Systems for Distillation. — Continuous
DISTILLATION OF CRUDE OIL
163
plants can, in the majority of cases, do the work of periodic
plants in a more efficient manner.
In addition to the considerations mentioned above, the
following advantages are derived. The general wear and
tear on the plant is much less as each section works at a
uniform, instead of a varying, temperature. The capital
expenditure for a given throughput is much less as fewer
stills are required ; the fuel consumption is less and operating
wages are lower. Moreover, a continuous system lends
itself much more easily to economical utilization of the
latent heat of condensation of the vapours and the specific
heat of the residues.
A simple continuous distillation plant consists of a
number of stills, usually from five to twelve, arranged
cascade faslu'on in a bench or battery, with a difference of
level of from six inches to a foot between successive stills,
each still being fitted with condensing arrangements. The
crude oil is admitted to the first still, whence it flows into the
second, thence to the third and so on through the whole
series, losing a certain percentage of distillate at each still,
and eventually issuing as residue from the last.
The arrangement of piping is simple, as will be seen
from the diagram (Fig. 20).
FIG. 20. — Arrangement of continuous stills.
164 PETROLEUM AND ALLIED INDUSTRIES
The crude oil enters the bench at A, flows into the
first still by the inlet pipe C, extending to the far end of
the still, flows out by the outlet pipe D into the next still,
and so on. The residue finally flows out at B. Each still is
provided with a by-pass valve E, so that any one still can
be cut out of the bench for cleaning or repairs. Each still
is fitted with its separate condenser, and in the better plants,
one or more "dephlegmators" or fractional condensers are
fitted in the vapour lines, so that from each still several
separate distillates may be obtained.
The system is regulated so that each still is kept at
a constant temperature and yields a vapour of constant
composition, giving a distillate (or series of distillates) of
constant composition.
The working temperature for each still depends upon the
number of stills in the bench, and on the nature of the
crude, as it must be arranged that each still does approxi-
mately the same amount of work.
The table on next page shows the Engler distillation
tests of a series of distillates from a continuous bench and
illustrates how these distillates vary in composition, and how
they may be grouped together. In this case each still was
fitted with two dephlegmators or air condensers, each of
which yielded a distillate, while a third distillate, which
passed through the dephlegmators without condensation,
was condensed in a separate condenser. These three
distillates are designated Di, D2, D3 respectively.
Distillate iD2, iD3, 2D2, 2D3 could be collected
together as " straight-run benzine distillate " ; 2Di, 3Di,
3D2, 3D3, 4^2, 403, 503 together as " benzine-kerosene
distillate for redistillation " ; 6Di, 702, and perhaps 8D3,
might be collected for redistillation into kerosene and
gas oil.
In continuous systems of distillation use may be made of
the heat of the outflowing residue, the temperature of which
may be over 300 ° C. This residue must in any case be cooled,
so its available heat can be economically used for preheating
the ingoing crude oil before entering the first still of the
DISTILLATION OF CRUDE OIL
165
bench. This is effected by means of "heat exchangers/'
many types of which are in use. The most efficient
type is the tubular. This is constructed like a tubular
condenser, but is usually placed in a horizontal position
(Fig. 21, p. 166).
Still no.
Distillate.
Sp. gr.
@i5°C.
Percentage of distillate boiling up to
ioo°C.
i5o°C.
200° C.
25o°C.
300° C.
Flash pt.
I
2
Di
D2
E>3
0732
0726
30
48
no
90
93
conde
all
all
nsatio
n
ord. temp.
a a
Di
D2
D3
0770
0765
0-750
I
12
2O
54
65
75
93
97
all
all
all
—
•
3
Di
D2
D3
0-785
0-777
0-765
5
<t
58
80
88
95
all
all
all
—
'
4
Di
D2
D3
0-815
0-807
0-785
I
3
10
30
50
65
75
79
92
all
all
all
40° C.
30° c.
ord. temp.
S
Di
D2
D3
0-825
0-816
0-800
—
3
15
32
5°
70
70
80
90
97
all
all
42° C.
££
6
Di
D2
Da
0-840
0-831
0-818
— •
i
8
20
42
38
50
75
85
93
98
46° C.
43° C.
37° C.
7
DI
D2
r>3
0-854
0-844
0-829
—
—
I
20
10
3°
48
60
82
90
—
8
DI
D2
I>3
0-866
0-855
0-847
—
con
tains
wax
12
65
—
The cold crude oil enters at C, and after being heated by
the hot residue flowing counter-current from A to B, emerges
hot at D. In the case of cnide oils which contain a large
percentage of residue, the quantity of heat disengaged may be
so great as to allow even of a little distillation taking place
in the heat exchanger, which may then be fitted with a
166 PETROLEUM AND ALLIED INDUSTRIES
dome vapour pipe and condenser, and thus function as a
still.
Although such a continuous bench is an undoubted
improvement on a battery of periodic stills, it is, however,
£
FIG. 21. — Tubular heat exchanger.
far ' from efficient, the efficiency indeed rarely exceeding
35 or 40 per cent. This efficiency can, however, be improved
in various ways, e.g. by utilizing the latent heat of the vapours
for heating and even partly distilling the incoming crude,
FIG. 22. — Distillate-crude oil preheater.
and by inserting heat exchangers or economizers in the flue
gases. Many modern continuous benches are fitted with a
series of distillate preheaters (Fig. 22). These preheaters are
practically stills heated by internally placed coils through
DISTILLATION OF CRUDE OIL
167
which the vapours from the main stills are passed, these
vapours being therein completely or partially condensed.
The vapours from the main stills enter the distillate
preheater at A and are partially condensed in passing
through the nests of tubes B, thereby heating the contents
of the preheater. The condensed vapours pass off by the
lower pipe D to their coolers, the vapours which have
escaped condensation passing on by the pipe C to further
water-cooled condensers. Each preheater is connected up
with inlet and outlet pipes just as is a continuous still.
Figure 23 illustrates the principle of such an arrangement.
FIG. 23. — Arrangement of still fitted with distillate preheater.
i is the main still ; 2, the main vapour pipe ; 3, the distillate
preheater in which the crude is heated and to some extent
distilled by the latent heat of the condensing vapours ;
4, the condenser for the distillates given off from this distillate
preheater ; 5, the cooler for the condensed vapours which
issue from the heating coil of the distillate preheater ; and
6, the condenser for the vapours which escape condensation
in that heating coil.
From every set of main stills and distillate preheaters,
therefore, three distinct distillates may be obtained.
The following table will give some idea of the manner in
which the distillate preheaters function : —
168 PETROLEUM AND ALLIED INDUSTRIES
Per cent, distilling in Engler
Sp. gr.
flask up to
@i5°C.
100° C.
i50°C.
200° C.
250° C.
Portion of the distillate from a main
still condensing the distillate pre-
heater
0-804
—
—
57
92
Portion of same distillate escaping
condensation in the distillate pre-
heater, but condensed in water-
cooled condenser
0783
—
51
95
all
Vapour distilled off from the dis-
tillate preheater . .
0-698
76
97
all
— ,
In a complete plant arranged on this system (Fig. 24)
the crude oil enters the residue heat exchanger D, where
it is heated up by the outgoing residue to such a temperature
FIG. 24. — Arrangement of continuous bench with preheaters.
that it may even begin to distil the vapours condensing in
condenser C n. The temperature to which the crude oil
will be heated depends naturally on the percentage of
residue from the crude, and this may vary between very wide
DISTILLATION OF CRUDE OIL 169
limits for various crudes. The crude oil then passes through
the distillate preheaters B i , B 2 in succession, and then through
the main stills, A i — 4, finally issuing as residue from the last
still. The preheaters and also the stills are arranged in
cascade fashion, the former naturally at a higher level so
as to allow the crude oil to flow by gravity through the
series.
In the above diagram,
A 1—4 represent the main stills.
B i — 2 two double distillate preheaters, each containing
two separate sets of coils.
C i, C 4, C 7, C 10 coolers for the portions of main still
vapours condensed in the preheaters.
C 2, 03, C8, C 9 condensers for the portions of main still
vapours which escape condensation in the preheaters.
C 5, C 6 condensers for the vapours from the preheaters.
C ii condenser for vapour from residue heat exchanger.
D residue crude oil heat exchanger.
With such an arrangement very great fuel economy is
effected.
As a general rule the complete distillation of a crude
oil is effected in two stages. In the first stage the lighter
fractions, benzine and kerosene distillates, and perhaps a
little gas oil are distilled off. In certain cases no further
distillation of the crude is necessary, the residue, after the
removal of the benzine and kerosene being marketed as a
liquid fuel.
In many cases, however, it is desirable to work up this
residue further as (i) it may be too asphaltic and thick for
use as fuel oil directly as is the case with many Mexican
and Venezuelan fuels ; or, (2) it may contain so much
paraffin wax as to make the extraction of this worth while,
as is the case with Pennsylvanian, Mid-continent, and
Burmah crudes, for example ; or, it may contain valuable
lubricating oil fractions, which can be removed, e.g. Russian
crudes.
As much higher temperatures are required for completing
this distillation, somewhat different arrangements are
170 PETROLEUM AND ALLIED INDUSTRIES
necessary, consequently the second stage of the distillation
is usually carried out in a separate bench of stills.
The dephlegmators for lubricating oil stills are often
replaced by a series of horizontal pipes of large diameter,
through which the vapours pass on their way to the main
condenser. From each of these large pipes a condensate
fraction may be drawn off. These condensates will usually
be dry, as the steam should condense only in the condenser.
During distillation for lubricating oil fractions and for paraffin
wax relatively large volumes of steam are blown into the still
to avoid cracking of the oil as far as possible. In distilling
off the higher boiling-point fractions, the amount of steam
blown into the still may exceed the amount of oil distillate
obtained.
Certain crude oils, e.g. some from the Pennsylvanian
fields, may yield a cylinder oil residue after a large percentage
of the crude has been distilled off. Imbricating oil distillates
also are often concentrated down to heavier oils or cylinder
oils. In this case care has to be taken not to overheat the
oils, copious supplies of steam being used for this purpose,
and the fires being extinguished some time before the
end of the operation. As the quality of the distillates is
much improved by distilling under high vacuum, this
process is nowadays often applied.
A modern successful type of high vacuum plant is that
designed by Steinschneider (U.S. Pat. 981953) (Fig. 25).
The stills used (A) are of the usual cylindrical type often
fitted with an internal fire tube. They are strengthened
internally in order to stand the external pressure. They
are arranged in a bench of six or more for continuous
working. Each still is fitted with one or more domes
connected to a vapour pipe (B) of large dimensions, 14
inches or more, in order to allow the vapours to pass
away as quickly as possible so as to maintain a
vacuum in the still. This vapour pipe usually bends
back on itself once or twice forming an air-cooled con-
denser. Any distillates condensing here are pumped away
through a cooler.
DISTILLATION OF CRUDE OIL
171
This large vapour pipe leads into an air-cooled dephlegm-
ator C, in which a further fraction condenses, then into
a further water-cooled dephlegmator D, in which the bulk
of the distillate condenses. The vapours then, consisting
mostly of steam, pass on into the barometric condenser E,
where they are condensed by a jet of water. This baro-
metric condenser is placed at an elevation of over 30 feet
and the effluent pipe leads downwards to a water seal so
that the condenser forms practically a water barometer.
FIG. 25. — Arrangement for distilling under high vacuum.
The vent of this condenser is connected to a suitable air
pump.
The distillates running from the dephlegmators, after
passing through coolers run into sealed receiving tanks of
small capacity (not shown in the diagram), whence they are
pumped out by low-level pumps to the tail-house. This
arrangement of pumps enables the distillation plant to be
constructed without the necessity of making each distillate
discharge a barometer tube. All that is necessary is to
make the height of the discharge pipes equal to the head
which the pumps can easily maintain when evacuating.
Such a continuous bench of high vacuum stills can
172 PETROLEUM AND ALLIED INDUSTRIES
easily be operated at a pressure of only 10 or 15 centi-
metres pressure absolute, and under these conditions the
temperature of the oil in the still need not exceed 300° C.,
a temperature about 50° lower than would be reached
without vacuum. In order to avoid pumping out the hot
residue from the last still, it is usual to operate the last two
stills periodically and alternately, so that the one when its
contents are distilled as far down as desired, may be cut
out from the vacuum and pumped out while the other is
being rilled and functioning as last still.
Distillation for paraffin wax is carried out in similar
continuous plant, usually at atmospheric pressure. The
determination of the setting points of the distillates in this
case indicates how the distillation is proceeding.
In the case of certain crudes, e.g. some of the Pennsyl-
vanian, practically all the paraffin wax may be distilled off,
so that the residue in the still may be used as a so-called
steam refined cylinder oil. In the case of other crudes it
is impossible so to distil off the bulk of the wax ; much
remains in the residue, which forms a very thick asphaltic
substance, too thick for use as fuel. Attempts to distil
this further with the use of steam would result in the
production of very viscous distillates, containing wax
which would not easily crystallize. Both distillates and
residue would thus be very difficult substances to handle.
This thick residue is, therefore, usually further distilled
in so-called " tar or coking " stills. These are special stills of
strong construction, the bottoms of which are usually made
in one piece. They are usually set so that the whole of the
bottom is exposed to the furnace gases, no return flues
being used. They are often fired from the side instead of
from the ends, a more uniform distribution of heat being
thus obtained. The distillation is conducted rapidly with-
out the use of steam. A further yield of paraffin wax
distillate is thus obtained, which is thin and easily crystal-
lizable owing to the presence of these cracked oils. Towards
the end of the distillation the stream of distillate changes
in character owing to the presence of high melting point
DISTILLATION OF CRUDE OIL 173
hydrocarbons of the aromatic type. This distillate is known
as " wax tailings." When the bottom of the still shows dull
red, the fires are turned out, and the distillation is allowed
to complete itself. The residue is then a petroleum coke.
After cooling somewhat the still is opened and the coke is
dug out. The life of a still subjected to such strenuous use
is naturally short.
In the case of crude oils rich in asphalt, e.g. the heavy
crudes of Mexico, California, and Texas, the distillation
may be conducted so as to produce an asphalt to definite
specification. Distillation to asphalt is usually carried out
periodically in stills of large capacity, 100 tons or more.
The distillation may also be conducted in continuous
plants, the control being effected by examination of the
outgoing residue rather than by the character of the
distillates.
In order to obtain asphalt of good quality it is necessary
to avoid overheating, particularly as the periodic distillation
takes a considerable time (24 hours or more). Copious
supplies of steam are therefore blown into the still, so that
towards the end of the distillation, three or four times as
much water as oil is condensed in the condensers. The
distillates produced will usually be gas oils or perhaps light
lubricating oil distillate according to the grade of asphalt
produced. It is usual not to allow the temperature of the
oil in the still to exceed 350° C. during this operation.
During the last few years stills of the conventional type
have been to some extent replaced by the much simpler
tubular stills. The development of this type of plant
arose from the difficulty of handling crude oils containing
emulsified water in ordinary stills, as there is very great
danger of the whole contents of the still frothing or " puking "
over when the temperature passes 100° C. The distilling
operation must, therefore, be carried out with very great
caution. The idea of the tubular still for dehydrating such
crude oils was developed in the United States by Bell, Brown,
Trumble, and others. Its use was then extended to the
distilling off of light fractions from heavy crudes in order to
174 PETROLEUM AND ALLIED INDUSTRIES
raise the flash-point to liquid fuel standard. From this the
name " topping plant " was derived, a term now in general
use. The plant has now been considerabty further developed,
so that its use extends to the distillation of rich crude oils
yielding 60 per cent, or more of distillate, and to the distilla-
tion of heavy crudes down to asphalt. The principle of
such plants is very simple, the variations in construction
found are very numerous.
In general, the crude oil first flows through a series of
heat exchangers where it is heated by the condensing
vapours and by the hot residue. It then flows on to the
tubular retorts which consist of 4-inch tubes set in a furnace.
In passing through these tubes the oil is partially evaporated,
and any water it may contain completely so. The mixture
of oil vapour and steam then passes through an uptake pipe
to some form of separating box into which it issues as a
foam. Separation of the vapours takes place here; the
vapours pass off by suitable vapour pipes to the condensers,
and the residue passes off via the heat exchangers to the
residue tanks.
One fundamental difference between such a plant and a
continuous bench of stills is immediately noticeable. In
the case of the continuous bench each still yields a certain
fraction ; in the case of the tubular retorts the whole of the
distillate is taken off at once. In the case of the continuous
bench the residue in the last still is in equilibrium with the
vapours from the last still only, whereas in the separating
box of the topping plant the residue is in equilibrium with
the whole of the vapours. For any given percentage of
distillate, therefore, the flash-point of the residue from a
topping plant will be somewhat lower than that from a
continuous bench.
The taking off of the distillate en Hoc necessarily involves
considerable redistillation in order to effect the separation
into commercial fractions. This can be and usually is,
however, effected by means of fractional condensation and
partial redistillation by means of the heat of the residue.
A description of a modern complete plant working on
DISTILLATION OF CRUDE OIL 175
this system will, therefore, be given, a Trumble plant being
selected as representative.
The heaters or retorts are made up of 4-inch steel pipes
arranged in six rows, each of twelve pipes, placed one above
the other. The ends of these pipes are connected by flanged
return bends, which may be removed for cleaning purposes.
These bends are placed outside the brickwork setting of the
retort, and may be insulated either individually by asbestos
jackets, or by being enclosed in a space closed by folding
doors. The whole number of pipes are thus connected in
series as a single tube. Two such sections are set side by
side to make one battery. The heating is effected by liquid
fuel firing, the arrangement of the furnace being such that
direct flames do not play on the tubes. The most effective
method of heating is naturally the counter current method,
the heated flue gases descending round the nest of tubes
through which the crude oil passes upwards (Fig. 26).
The internal heating surface of two such heaters would
be 2430 square feet. These two heaters may be connected
in series or in parallel as required. Several thermometers
are fitted, so that the temperature of the crude oil as it flows
through the system may be accurately controlled.
Automatic controlling apparatus may now be obtained
actuated by the thermometer placed in the pipe leading
from the last retort to the vapour separating vessel. In this
way an increase of temperature can be made to bring about
an acceleration of the crude oil-feed pump and vice versa, so
that the personal element can be eliminated in this particular
case.
The working temperatures will naturally depend on the
nature of the crude oil being distilled and on the fractions
to be distilled off. The heated crude oil leaves the heaters
in the form of a foamy mixture of vapour and oil and passes
by an uptake pipe which discharges into the top of the
vapour separating vessel, where the vapours have an
opportunity of separating themselves from the residual oil.
In the case of the Trumble plant, this consists of a
vertical steel cylinder, 6 feet diameter and 25 feet high,
176 PETROLEUM AND ALLIED INDUSTRIES
DISTILLATION OF CRUDE OIL 177
which is enclosed in a brickwork stack, so that the flue gases
from the heaters can pass through the annular space
FIG. 27. — Trumble evaporator or separating vessel.
separating the brickwork from the steel cylinder, thus
effecting further distillation. Fitted inside this vessel is
a vertical vapour pipe closed at the top, which carries a
P. 12
178 PETROLEUM AND ALLIED INDUSTRIES
number of umbrellas the outside edges of which extend
almost to the cylinder walls. The object of this arrangement
is to ensure the liquid flowing down the sides of the vessel.
Directly under the apex of each umbrella the central vapour
pipe is perforated so that the vapours may enter. One or
more side pipes connected to this central vapour pipe allow of
the vapours being led off. A perforated steam coil is usually
placed at the bottom of this "evaporator" so that steam
may be admitted in order to assist in the distillation (Fig. 27).
An oil catcher, consisting of a small vertical cylinder
2 feet diameter and 3 or 4 feet high, containing a number of
perforated steel baffle plates, is placed in the vapour line, to
arrest any spray of heavy oil which might be carried over
mechanically with the vapours. Such an arrangement has
already been mentioned in connection with an ordinary
distilling plant (p. 156).
The residue, after leaving this evaporator or separating
vessel, may pass off through crude oil heat exchangers or may
be utilized for supplying the heat necessary for redistilling
some of the fractions, as described later. The residue-crude
oil heat exchangers are usually of the tubular type. The
number to be used depends on the nature of the crude and
the percentage of residue obtained from the plant.
The vapours, after leaving the separating vessel, pass
on, not directly to the main condensers, but through a
series of " dephlegmators " or fractional condensers. These
consist of vertical steel cylindrical vessels about 30 inches
in diameter and 7 feet high. These vessels contain a number
of horizontal saucer-shaped baffle plates. Half of these fit
closely to the walls and have a central hole, the other half
placed alternately are of smaller diameter with no central
hole. The vapours thus zigzag through the annular spaces
and central holes. The heavier fractions condense on these
plates and fall back to the bottom of the dephlegmator,
whence they are led off by a special pipe. At the top of the
dephlegmator is placed a water coil, by means of which a
certain amount of distillate may be condensed in order to
furnish a quantity to flow back down over the baffle plates.
DISTILLATION OF CRUDE OIL
179
IT"
In this way the dephlegmator functions to some extent as a
fractionating column (vide p. 190). Further below the
point at which the vapours enter the dephlegmator a further
number of baffle plates are situated and means is provided
for blowing in steam at the bottom, so that the down-flowing
condensate may be subjected to steam distillation (Fig. 28).
The main vapours pass
through several (as many
as eight in modern plates) 1° ? °1 / F° °U- I OUTLET
of these dephlegmators,
being thus condensed into
as many condensates which
flow from the bottom of
each dephlegmator. The
vapours from the last de-
phlegmator pass on into
condensers cooled by the
entering crude and finally
into water-cooled coolers.
These various distillates
may then be collected sepa-
rately in the tail-house, or
may be partly redistilled
in the ' ' separators . ' ' The
separators, several of which
may be fitted, consist of
rectangular boxes 18 by 6
feet by 40 inches high,
along the bottoms of which
run several 3-inch pipes
connected to manifolds,
through which hot residue can be run. These pipes
are supplemented by perforated steam pipes through
which steam can be blown. To the top of these boxes
vapour lines are attached. These separators are thus
practically stills. The condensates from the dephlegmators
which require further distillation, run into these separator
boxes where they are redistilled, the vapours passing through
IML.ET
d
1° ° °! /£ °
poo / p- o
boo ^jo O(
o
0
&
X
?
^
^ e J
i
r •
^~ .
[
^- •
[
«
6 .
h
/*- *
y
<
^ -
)
p- -
<
)
* -
• — »
(
• ' • "
'
«
x^JQis>/
FIG. 28. — Dephlegmator.
i8o PETROLEUM AND ALLIED .INDUSTRIES
condensers to the tail-house and the residues running off
through coolers.
The accompanying flow-sheet diagrams, Figs. 29 and 30,
FIG. 29. — Course of crude oil and residues through Trumble plant.
will explain the several courses of crude oil, residues and
vapours through the plant. These diagrams represent
simple cases only, and must not be taken to represent
FIG. 30. — Course of vapours through Trumble plant.
actual practice. The subject of topping plants or tubular
retort distillation plants is very well set forth in Bulletin
162, Petroleum Technology 45, U.S. Bureau of Mines, by
DISTILLATION OF CRUDE OIL
181
J. M. Wadsworth, where very full details as to plant and
operation are given.
The following table, giving the analyses of the products
obtained from the dephlegmators during an-actual run, will
illustrate to what an extent the total distillates taken off
en bloc may be separated by fractional condensation : —
Sample from
Distillation in Engler flask, percentages
boiling over up to
F. b. pt.
Fl.-pt.
100° C.
I50C.
200° C.
250° C.
300° C.
Dephlegmator i . .
2 . .
3 ••
4 ••
6 '.'.
Vapour from 6 . .
7
I
87
X3
33
70
95
5
ii
65
90
40
78
>350
350
299
265
235
225
175
90° C.
75° C.
46° C.
33° C,
25° C.
i6°C.
Of the above products Di would run to gas oil, D2 might
be worth redistilling to extract therefrom some kerosene,
D3 and D4 might run to kerosene distillate, 05 should be
redistilled and perhaps D6. The vapour from 6 would
naturally run to heavy benzine. The work of the separators
is exemplified by the following analyses : —
—
100°.
125°.
150°.
175°.
200°.
F. b. pt.
Flash-point.
Oil running to
separator
— •
—
15
53
80
235
20° C.
Distillate from
separator
— .
22
7°
93
192
— .
Residue from
separator
—
2
38
75
245
33° C.
It will be seen, therefore, that such a distillation plant is
complete in itself, as it yields a series of finished products
which do not require to be subjected to a further process of
redistillation. Such a plant, therefore, presents many ad-
vantages over the system of stills and redistillation stills
usually employed. It is more compact, much less steel
is required in its construction, the need for tanks for
182 PETROLEUM AND ALLIED INDUSTRIES
intermediate products disappears, there is minimum loss of
heat as the products for redistillation are not cooled before
passing into the separator, i.e. redistillation stills. The
fuel consumption is low and the efficiency relatively high
compared to those of an ordinary distilling plant.
Though in the first place designed for dehydrating or
FIG. 31. — Details of header for tubular still.
topping crude oils, the system has been extended to dealing
with crude oils yielding as much as 60 per cent, of distillates.
In such cases, however, limitations are imposed by the lack
of heat necessary for redistillation, owing to the low per-
centage of residue available.
Tubular or pipe stills are now coming into general use
for various purposes, such as preheating crude oil preparatory
DISTILLATION OF CRUDE OIL
183
to pumping it through long pipe-lines, and for cracking
furnaces.
It is obvious that the circulation of the oil in a pipe still
must be much better than can be possibly attained in a
cylindrical still, consequently the chances of overheating
the oil are much less. Even if coke is formed, it can be
FIG. 32. — Special type of tubular still or heater.
easily removed, and moreover, if coke deposition goes so far
that tubes are damaged, then these can be quickly and
cheaply replaced. Patching the bottom of a cylindrical still
is a difficult and expensive job and unsatisfactory when
finished. Much better heat exchange is possible as oil and
furnace gases can run counter current, fuel consumption
being thus reduced. Moreover, the still can be designed so
184 PETROLEUM AND ALLIED INDUSTRIES
that the fuel can be properly burnt in a suitably designed
furnace. In modern types, the pipes of the tubular stills
are constructed with a covering of cast-iron corrugated
sleeves, similar to those used in Foster superheaters (Fig. 31).
One of the difficulties in distilling oils at high tempera-
tures, such as are necessary for cracking, whether it be in
cylindrical or tubular stills, is the deposition of coke on the
still walls. Although this cannot be entirely avoided it can
be minimized in the case of tubular stills by designing the
plant so that the tubes are not exposed to direct radiation.
In a still recently designed by the Power Speciality Company
this has been effected in an ingenious manner (Fig. 32).
In the roof of the furnace are placed a series of tubes
B, through which the crude oil to be distilled is first circulated
before passing to the main heating tubes D. The portion
of the roof covering the combustion chamber is lined with a
covering of insulating material, so that the pipes in this
area are protected from direct radiation. The pipes in
the area of the roof directly over the main heating tubes
are thus not exposed to any extent to any direct radiation,
and their presence prevents this portion of the roof becoming
red hot. Consequently, the main heating tubes D are
protected from the direct radiation which they would receive
from the roof were the tubes B not placed there. This
arrangement has proved very efficient in practice and is
undoubtedly a marked advance in the construction of
tubular stills.
The efficiency of the older types of periodic still, with
simple furnace settings and no arrangement of heat
exchangers, must have been low indeed. The efficiency
of many, if not most, plants operating at the present
day leaves much to be desired. A simple calculation,
taking the specific heat of oil at 0*45 and the latent heat
at 70 calories, would show that a fuel consumption of
1*2 per cent, reckoned on the crude oil treated would be
theoretically sufficient to distil off say 50 per cent, of distil-
lates, allowing for no heat exchange arrangements whatever.
In actual practice, with no heat exchange, distilling
DISTILLATION OF CRUDE OIL 185
periodically with old-fashioned plant, a fuel consumption
at least six or seven times as high would be required.
Wadsworth (U.S. Bureau of Mines, Bulletin 162) cites a
case where the overall efficiency of a battery of crude oil
stills working continuously, fitted with residue-crude oil
heat exchangers, amounted to 34*8 per cent. He also cites
the case of a modern Trumble plant adequately supplied
with heat exchangers and separators as 57 per cent. Even
such a figure leaves room for considerable improvement
when it is considered that the efficiency of modern Spencer-
Bonecourt steam boilers is actually over 90 per cent. There
is no reason, however, why a battery of continuous crude
oil stills, equipped with distillate preheaters, residue-crude
oil heat exchangers, and heat exchangers placed in the flues
(after the fashion of a Green's economizer) should not have
an efficiency as high as that of a tubular retort distillation
plant. It is naturally, however, much more easy to ensure
an efficient furnace in the case of a tubular still. With
highly efficient continuous batteries, however, the fuel
consumption, when distilling an oil yielding 70 per cent, or
so of distillate, may be reduced to below 2 per cent, of the
crude oil distilled.
The methods described above are those in general use
in the petroleum industry. There are undoubtedly still
great possibilities in the direction of more efficient distilling
plant. One of the great objections to distilling oil at high
temperatures in any usual form of plant, especially in
cracking plants, is the formation of coke on the inside of
the still or retorts. Such coke, being a poor conductor of
heat, gives rise to overheating of the iron plate through which
the heat must be transmitted, so that damage soon results.
An obvious way of getting over the difficulty would seem to
be the method of distillation by direct contact with heated
gases, a method which is successfully applied to the concen-
tration of sulphuric acid. This idea is, in fact, very old.
In 1860, W. Gossage (Eng. Pat. 1086) patented a method of
distilling bituminous substances by injecting highly heated
gases obtained by the combustion of suitable fuel. D alley
186 PETROLEUM AND ALLIED INDUSTRIES
'II
II ^
I, I
ill
.9
H '43
— ^ if— ?
s
i!
i*
££ 81
•!JQH*'3'«-
Is J
*
i
I
DISTILLATION OF CRUDE OIL 187
(Eng. Pat. 163347, July 21, 1919) proposes to inject a
spray of the oil to be distilled on to the surface of solid fuel
in a retort or producer, air for combustion being blown in
at the bottom. Knibbs (Eng. Pat. 165863 of July n, 1921)
suggests an apparatus based on the same principle.
As far as the writer is aware, this method of distilling
by direct contact with furnace gases, which seems to present
such obvious advantages, has not as yet found successful
application.
As crude oils show such great variation in character, a
definite working scheme must be drawn up for each individual
oil. Two diagrams are given above illustrating typical
methods of working up crude oils.
Fig. 33 illustrates the simple case of working up a
crude oil into benzine (motor spirits), kerosene, gas oil and
liquid fuel only, the fuel residue being further, perhaps,
worked up into lubricating oils and asphalt.
Fig. 34 represents a scheme for working up a paraffin wax
base crude oil. Reference will be made to this diagram in
further sections of this work.
GENERAL REFERENCES TO PART VII., SECTION A.
Bacon and Hamor, " The American Petroleum Industry, " vol. 2
McGraw Hill.
Campbell, " Petroleum Refining." Griffin and Co.
Engler-Hofer, " Das Erdol." vol. 3. Hirzel, Leipzig.
Wadsworth, Bulletin 162, U.S. Bureau of Mines.
SECTION B.— REDISTILLATION AND FRAC-
TIONATION OF LIGHT OILS
IT has been pointed out that in the ordinary process of
distillation of crude oil, a fraction intermediate between,
or rather consisting of, benzine and kerosene is obtained.
The more efficient the system of primary distillation, the
smaller this fraction. In general, however, quantities of
such distillate must be redistilled in the average refinery.
Moreover, fractions of definite boiling ranges, special boiling-
point spirits, white spirits, and so forth are often required.
For the manufacture of such benzines a more or less intensive
fractionation is demanded.
In the simplest cases a separation of the light oils into
benzine and kerosene only is required. As the difference
in price of these commodities is considerable endeavours
should be made to obtain a separation as sharply as possible.
Generally, however, sufficient attention is not paid to this
point and the separation is by no means well effected. The
benzine from the average refinery may boil up to 200° C.,
and the kerosene may have as much as 30 per cent, boiling
below that temperature.
This redistillation is usually carried out in so-called steam
stills, which may be, and often are, operated continuously.
They differ little from ordinary crude oil stills chiefly in the
mode of heating. This is usually effected, as the name
indicates, by means of steam. Nests of high pressure steam
coils are arranged in the lower part of the still, the exits being
fitted with steam traps. Steam at pressures up to 160 Ibs.
pressure is usually employed. This enables temperatures
up to about 170° C. to be obtained in the still. As in the
1 88
REDISTILLATION AND FRACTION ATION 189
case of crude oil distillation, live steam is also blown in through
perforated pipes lying on the bottom of the still to assist the
distillation.
Direct firing may also be employed, but in some cases
this tends to discolour the kerosene residue left in the still,
thus rendering necessary a more intensive treatment. The
control by means of steam coils is easier, but the fuel con-
sumption is naturally much higher.
The steam stills are usually fitted with some form of
simple dephlegmator, sometimes water-cooled, sometimes
air-cooled. In many cases, however, no dephlegmator is
employed, the fractionation being so much the less efficient.
In cases where efficient fractionation is required, efficient
columns are used.
The benzine-kerosene distillate is distilled in such stills
until the residue shows the requisite flash-point, care being
taken that the final boiling point of the distillate does not
exceed a predetermined value.
The following table shows the result of distilling such a
benzine-kerosene fraction in a simple steam still with a
simple type of dephlegmator : —
Benzine-kerosene
Engler distillation. distillation before
distillation.
Benzine distillate.
Kerosene residue.
Up to 125° C.
2 per cent.
.
150° C.
4 per cent.
3i
—
175° C.
3i
75
—
200° C.
65 „
98 ,,
20 per cent.
225° C.
88
all
66
250° C.
95
—
86
27S°C.
all
—
95
Final boiling point
265
200
285
40 per cent, of benzine distillate and 60 per cent, kerosene
residue being obtained in this case.
The benzine distillate would be mixed with the straight-
run benzine from the primary distillation, and the residue
with the kerosene' distillate. The percentage of benzine-
kerosene distillate obtained from any crude oil will depend
PETROLEUM AND ALLIED INDUSTRIES
on (a) the nature of the crude oil, (b) the efficiency of the
primary distillation. In practice, for example, an actual
crude oil yielded : —
Straight-run benzine distillate . . 11*3 per cent.
Benzine-kerosene distillate . . 15*7 ,,
Direct kerosene distillate . . 10*3 ,,
Residue . . . . . . . . 61-5
lyOSS .... . . . . . . I '2
The straight-run benzine distillate would be cut so as
to give a final boiling point of not more than 200° C. The
direct kerosene distillate would be cut so as to give a flash-
point of about 100° F. and final boiling point not over
say 280° C., the intermediate fraction being redistilled as
described above.
In many refineries, however, quantities of benzines of
narrow boiling point ranges are made. Such benzines, for
example, are " lighting spirits/' used for producing air gas, or
" petrol gas," for lighting purposes. Such benzines must be
very volatile, boiling completely below 100° C. For dry-
cleaning purposes, vegetable seed extraction, and so forth,
benzines boiling between say 80° C. and 100° C., or 100° C.
and 120° C. are required ; for solvent purposes benzines
boiling between 100° C. and 150° C. may be demanded;
and for " white spirits/' or " mineral turpentine/' benzines
boiling between 140° C. and 200° C. may be required. The
manufacture of such spirits necessitates the use of efficient
"fractionating columns."
The equipment necessary for such distillation consists
of a still of the usual type, a fractionating column and a
dephlegmator for returning a supply of condensate to run
back through the column.
Fractionating columns may be of several types, e.g.
simple columns fitted with baffle plates, bubbling columns of
the Heckman type, or columns of the absorption type filled
with rings or other form of packing.
Columns fitted with perforated plates are largely used
REDISTILLATION - AND FRACTION ATION 191
in the coal-tar industry for the extraction of toluene and
xylene from light coal-tar benzols. The vapours pass
upwards through the perforated plates, being subjected to a
scrubbing action by the enforced bubbling through the layer
of liquid on the plates. Such simple columns cannot,
however, be well controlled as the plates would drain dry
when running slowly. In columns of the Heckmann type
a layer of liquid is maintained on the plates, the up-going
vapours being forced to take one path, the down-coming
liquid another. The action of such a column is best explained
by reference to the diagram (Fig. 35) . The column, which may
be 20 feet high and 5 feet diameter,
is fitted with a number of plates
or trays 9 inches or so apart.
Each tray is fitted with one or
more down-take pipes, the top of
which projects a short distance
above the tray, and the bottom
of which extends almost to the
underlying tray, projecting below
the level of the liquid on that
tray, so that the lower end is
sealed. The distance to which
the upper end of the liquid down-
take pipes A project above the FIG. 35. — Heckmann column,
tray determines the depth of
liquid which remains on that tray. Bach tray is fitted
with a large number of vapour up-take pipes, the upper
ends of which project above the level of the liquid on
the tray. These up-take pipes are covered with hoods,
the edges of which are usually serrated and which dip into
the liquid lying on the tray. The vapours are thus forced
to take a path, bubbling through the layers of liquid, while
the returning liquid flows back down the column by the
down-take pipes.
The vapours issuing from the top of the column pass
through a dephlegmator on their way to the condenser.
In this dephlegmator they are partially condensed, the
ig2 PETROLEUM AND ALLIED INDUSTRIES
condensate being returned by a sealed pipe to the column.
The amount of condensate so returned to the column
which determines the efficiency of the fractionation may
be controlled by the water supply admitted to the
dephlegmator (Fig. 36).
FIG. 36. — Complete fractionating plant.
By means of such a column, fractions boiling over a
range of only a few degrees C. may be obtained.
The process of fractionation as it goes on in the column
is well exemplified by the following analyses of five fractions
taken simultaneously from various points in a Heckmann
column : —
REDISTILLATION AND FRACTIONATION 193
Samples from
column.
Initial boil-
ing point.
Distillation in Engler flask. Per cent,
boiling up to temperatures °C.
Final boil-
ing ^int.
105
105/110
110/115
II5/I20
120/125
Top I . .
2 . .
3 -•
4 ..
Bottom 5
98
IOO
101
IO2
103
48
37
14
4
46
54
68
66
32
8
13
21
38
4
16
4
7
112
II4
II7
I24
J34
The following table gives analyses of samples taken
at various points simultaneously : —
Sample. ; fP- fj-
Initial
boiling
point.
Distillation in Engler flask.
Per cent, boiling up to °C.
Final
boiling
point.
•
°C.
125°
135° 150° 170°
°C.
!
Liquid in still . . ! 0-766
124
22 ' 68 91
197
Vapours in still o'755
no
—
—
39
— 94 all
165
Vapour from top
of column . . 0-739
96
49
98
—
— — —
no
Liquid returning
from dephleg-
mator . . 0-743
98
16
—
—
— , — —
112
Liquid from con-
denser . . 0-734
1
94
88
—
—
— — — ,
104
Should a fraction of very narrow boiling range be required
redistillation of a fraction may of course be necessary.
The type of fractionating column filled with rings or
some other type of packing is as yet little used in the
petroleum industry. High efficiency is, however, claimed
for this type of column. It presents the advantage of a
very great wetted surface for contact between vapour and
scrubbing liquid.
Raschig (Bng. Pat. 6288/14) patented simple rings;
modifications of such rings with even greater surface have
been patented by jessing, Prym, Goodwin, and others.
These rings may be made of various materials and dimensions.
If made of sheet iron 25 mm. high and 25 mm. diameter,
55,000 may be packed into a cubic metre, and so present
a total surface of 220 square metres.
P. 13
194 PETROLEUM AND ALLIED INDUSTRIES
The following data supplied by Dr. I^essing illustrate
the superiority of such a column over a column of the Coff ey
type for removing benzol from a solution of this in a heavy
green oil. In this particular case the column was employed
to remove the benzol from the scrubbing liquid used for
absorbing the benzol from coal gas. The columns compared
were of the same height, but of different diameters, that of
the Coffey column being 2 feet, that of the ring column
1 8 inches. The volume of the ring column was therefore
only 56 per cent, of that of the other.
Coffey column.
Ring column.
Benzene and toluene in benzolized
oil
Benzene and toluene in debenzol-
3-85 per cent. vol.
3-8 per cent.
ized oil . .
I-35
0-4
Benzene and toluene in crude
benzol distilled off
73'5
79'5
Efficiency of recovery of benzene
and toluene
66'i
89-6
Throughput of column gallons per
day
1065
890
These figures indicate the superiority of the ring column,
especially when taking into consideration its much smaller
volume.
The objections to this type of column would apparently
be the difficulty of running with small quantities of return
liquid and the possibility of channelling, i.e. of the vapours
taking the path of least resistance, and thus diminishing
largely the contact area.
Numerous other types of columns have been patented.
Those designed by Kubierschky (Chemical Age, June 21,
1919, p. n) are designed so that the hot vapours enter at
the top of each compartment of the column and leave at the
lowest point, passing from one compartment to another by
vapour up-take pipes leading from the bottom of any one
compartment to the top of that immediately above it, while
the liquid flows back through the finely perforated plates
which form the bottoms of the compartments.
REDISTILLATION AND FRACTION ATION 195
The fuel consumption for carrying out such distillation
is necessarily high owing to the large quantity of distillate
which is condensed and returned to the still to be again
distilled. The amount of distillate obtained per ton of
steam used in a simple distillation without fractionation
may amount to 10/12 times the amount obtained when
distilling to obtain a fraction of 20° range of boiling point.
Several such stills with columns may be arranged to
work in series continuously. Such plants do operate and
successfully separate benzene, toluene, and xylene contin-
uously from crude coal-tar naphtha.
Really intensive fractional distillation, however, is not
adopted in the petroleum industry. The isolation of pure
products from petroleum by distillation on the large scale
would be very difficult if not impossible, and would be so
costly as to be quite out of court as a commercial process.
The subject of commercial fractional distillation can be
much better studied in connection with the coal tar, alcohol,
and other industries.
GENERAL REFERENCES TO PART VII., SECTION B.
Gay, " Distillation et Rectification," Chemie et Industrie, vol. 3, p. 491.
Hausbrand, " Die Wirkungsweise der Rektificir- und Destillir-Apparate."
Mariller, " La Distillation Fractionee." Dunod et Pinat.
Thorpe, " Dictionary of Applied Chemistry," p. 263. Longmans.
Ullmann, " Enzyklopadie der Technische Chemie," Part III. p. 719.
Urban and Schwarzenberg, Berlin.
Warnes, " Coal Tar Distillation." J. Allen and Co.
SECTION C.— THE CHEMICAL TREATMENT
OF PETROLEUM AND SHALE OILS
THE products obtained by distillation are comparatively
seldom marketable without chemical treatment. Benzines
from certain crudes, e.g. those of Sumatra, are, however, so
free from bad smelling and objectionable constituents as to
be directly marketable, but kerosenes and lubricating oil
distillates practically always need refining.
The particular method of treatment employed depends
largely on the nature of the product to be treated, and on
the extent to which it is desired to improve the quality.
In the case of benzines which are to be used for such purposes
as the extraction of edible oils from seeds, the removal of
all objectionable constituents is of prime importance. The
impurities usually present are sulphuretted hydrogen and
organic sulphur compounds of the mercaptan, thioether, or
thiophene type. In some cases, particularly when ' ' cracked ' '
products are present, reactive unsaturated hydrocarbons
must be removed. In rare cases pyridins may be found as
impurities, and in benzines derived from the distillation of
shale oils or coal tars phenols may also be present. The
removal of phenols and pyridins presents no difficulties, the
usual methods of washing with dilute alkali and dilute acid
being adopted as in the coal-tar industry.
The removal of certain sulphur compounds or the
desulphurizing of oils is a problem which has excited the
interest of many chemists, but has not so far met with any
solution of general application. Sulphuretted hydrogen
may easily be removed by means of strong caustic soda
alone. The other sulphur compounds present difficulties.
196
TREATMENT VF PETROLEUM OILS 197
This problem is of particular importance in the case of
shale oils. Such oils usually contain sulphur compounds,
sometimes to a considerable extent, so that the actual
sulphur content may sometimes be as high as 7 or 8 per cent.
Any method devised for the desulphurizing of oils must,
of course, not only be a technical but a commercial success.
The cost of the refining process must be reasonable.
Strange to say, the method of refining first introduced
is still that in most general use to-day. Sulphuric acid
is the agent mostly used. This method of treatment is
in general use for benzine, kerosene, and lubricating oil
distillates. In general principle the method adopted for
these three distillates is the same. The benzine is violently
agitated in a suitable vessel with the necessary percentage
of concentrated sulphuric acid, the tarry residue separates
out and is drawn off, the benzine is washed with water,
treated with caustic alkali, and again washed. The acid
treatment is usually given in two or three portions, the sludge
being drawn off before the addition of the next charge.
Generally, amounts of acid up to 2 per cent, or even more
may be used in the case of benzines ; in the case of certain
lubricating oil distillates as much as 25 per cent, of acid
may even be necessary. Economy may often be effected
by using the sludge from the second or third treatment, as
acid for the first.
The function of the sulphuric acid is not fully under-
stood. It appears to act, certainly in the first application,
as a drying agent ; it undoubtedly absorbs unsaturated
hydrocarbons and even aromatics, and it removes also
oxygenated bodies. It undoubtedly also acts to some
extent as an oxidizing agent, as sulphur dioxide is usually
evolved during the refining process. The strength of the
acid is an important factor. If this falls below 97 per cent,
the efficiency rapidly diminishes.
Oleum of various strengths may be used, but it must
be remembered that the stronger the acid, the more
readily aromatic hydrocarbons are sulphonated. As these
hydrocarbons are the most valuable from a motor fuel point
198 PETROLEUM AND ALLIED INDUSTRIES
of view (vide Ft. VIII., Sect. A), it is advisable to avoid
their removal during the treating process as far as possible.
The presence of nitric acid in the sulphuric acid is un-
desirable, as this will form nitro-compounds with aromatic
hydrocarbons which will give a yellow tinge to the finished
products. The presence of selenium dioxide is stated to
have the same effect. It is commonly observed that
distillates which have been standing for a long time are
more difficult to refine.
After the successive acid treatments the benzine is
allowed to stand until all the acid sludge has settled down.
This is then drawn off, the benzine is washed with water
and then neutralized with caustic soda. Of this, usually
only a very small percentage is required. A further wash
with water after draining off the soda sludge, usually com-
pletes the process.
Mixing is effected by either mechanical means or by
blowing in of air. In either case the operation is usually
conducted in an " agitator." This consists of a steel cylin-
drical vessel fitted with a conical bottom. The capacity
is usually not over 20 tons for mechanically operated
plant, but when air-mixing is used, vessels of 200 tons
or more capacity may be employed (Fig. 37). In either
case the agitator is fitted with an inlet pipe for the benzine,
and inlet pipes for acid and soda. The chemicals may be
blown up into the agitators by means of montejus, or may
be run in from measuring tanks placed above. The latter
is the preferable method.
Mechanical agitators are fitted with a central shaft
carding some sort of propeller. The whirling round of the
contents of the agitator as a whole is avoided by baffle
plates dipping just below the surface of the liquid. Such an
arrangement produces a very lively agitation and thorough
mixing of the liquids. In the case of air-operated agitators,
the air is led down into the tip of the cone by means of a
4-inch pipe. The agitator (or at any rate the conical
portion) is often lined with lead.
The top of the agitator is completely closed in, and
TREATMENT OF PETROLEUM OILS 199
usually fitted with a number of explosion doors. These
are arranged so as to open outwards, and automatically
fall back into position. Steam pipes are also usually led
into the top of the agitator. This is advisable, as the
vapours above the liquid have often been known to flash.
Should this occur the explosion doors fly open and relieve
the pressure, thus preventing the roof of the agitator from
being blown off. It is in some refineries common practice
to blow steam into the top of the agitator during the period
MI* tHt.fr -*• :
i
FIG. 37. — Agitators.
of introduction and mixing with soda, as this, strangely
appears to be the danger point.
At the bottom of the cone is placed a main valve con-
nected to a cross piece, by means of which the acid sludge,
waste soda, washings, and the finished product may be drawn
off to their various receptacles (Fig. 37).
In the case of benzines, agitation by means of air is
inadvisable owing to the large evaporation losses caused.
Where the refining loss may be less than i per cent, when
mechanical agitation is used, it may be more than double
200 PETROLEUM AND ALLIED INDUSTRIES
that amount when air agitation is used, particularly, of
course, in a warm climate.
The method of treatment as outlined above is that in
most general use for benzines and kerosenes. For lubricating
oil the techniqiie of the method is somewhat different (vide
p. 203) . The same method is sometimes applied to the treat-
ment of paraffin wax, and it will be remembered that sulphuric
acid is also used for the refining of ozokerite or natural wax.
Many sulphur-containing oils, however, do not readily
yield sweet-smelling, marketable products by such a com-
paratively simple treatment. Numerous methods for treat-
ment of such oils have been described, but comparatively
few are in successful operation. Certain of these methods
are directed to remove the sulphur from the crude oil. In
many cases, such as, for example, the crudes of Mexico,
rich in asphalt, of which sulphur is an essential or consti-
tutional component, such a method would be inapplicable.
The problem of desulphurizing the crude is, however, of
relatively minor importance as there is no objection to the
presence of sulphur compounds in a fuel oil or asphalt. A
method applied to the crude oil is that designed by Frasch
(/. Ind. and Eng. Chem., vol. 4, p. 134). The sulphur
rich crude oils of Canada and Ohio are distilled in a flat-
bottomed cylindrical still in presence of copper oxide. The
still is fitted with a vertical shaft carrying horizontal arms,
to which hanging chains are attached. By this means the
copper oxide is kept in suspension in the oil. After the
bulk of the oil has distilled off, a further charge is added
and the process repeated, and this may be carried out four
or five times. The residue and the copper oxide are then
pumped out through a filterpress, the copper oxide being
thus separated off and regenerated by roasting. The same
process is sometimes carried out in another way, the vapours
of the distillate being made to traverse a cylindrical vessel
in which revolves a steel brush, dipping into a mixture of
heavy oil and copper oxide in the lower part of the vessel.
The vapours passing through the teeth of the revolving
brush are thus subjected to the copper oxide and so refined.
TREATMENT OF PETROLEUM OILS 201
Another method in common use is that in which sodium
plumbite is used. The benzine (or kerosene) is treated
with a saturated solution of litharge (PbO) in strong caustic
soda. A heavy black sludge is formed and the benzine
remains black owing to the presence of suspended lead
sulphide. A trace of flowers of sulphur is usually added,
which completes the precipitation of the lead sulphide.
After drawing off the sludge, the benzine or kerosene is
washed with water. This process may be used in connection
with the ordinary acid treatment.
Innumerable other methods of treatment have been
devised. Colin and Amend (U.S. Pat. 723368 of March 24,
1903) recommend the use of an alkaline hypochlorite in
presence of a catalytic agent, such as manganese dioxide.
Dunstan (Eng. Pat. 139233) uses an alkaline hypochlorite
and regenerates this elect rolytically after use. H. A. Frasch
(U.S. Pat. 525811 of 1894) also advises the use of a hypo-
chlorite. Hall (Eng. Pat. 26756 of 1913) recommends the
use of sulphur dioxide, followed by a distillation, claiming
that a large amount of the sulphur is thereby converted
into a form which may be easily removed by the ordinary
methods.
The refining of shale oil benzines and cracked benzines
presents difficulties owing to the presence of unsaturated
hydrocarbons. Treatment with a dilute sulphuric acid
(80 to 90 per cent.) often suffices to remove the more
objectionable of these, particularly the diolefines wrhich
readily condense up to form resinous bodies. Brooks and
Humphrey (/.S.C.7., 1918, 3i6A) have investigated this
question and have concluded that during the refining by
sulphuric acid two actions take place simultaneously, viz.
the olefines are partly removed and partly polymerized,
neutral alkyl esters being formed at the same time. These
latter and the polymerized products may remain in the
oil, and account for the increase of specific gravity some-
times noticed in refining such benzines.
Methods of refining cracked benzines, dependent on the
use of colloidal or absorbent substances have been proposed.
202 PETROLEUM AND ALLIED INDUSTRIES
Hall (Kng. Pat. 12100 of 1917) proposes passing benzine
vapours through fuller's-earth, kept at a temperature above
the final boiling point of the benzine. The columns of
fuller's-earth are kept at constant temperatures by means of
oil baths, and the benzine vapours are passed through the
columns in series. It is claimed that the issuing vapours
when condensed have completely lost the odour characteristic
of cracked spirit. The fuller's-earth appears to have the
power of causing polymerization of the unsaturated hydro-
carbons to take place, so that high boiling condensation
products are formed which may be drawn off from the
columns. The fuller's-earth in course of time loses its
efficacy and needs regeneration, after which it can be
reused.
The methods of refining above described are in the main
applicable to kerosene also. The application of these
methods, while producing a kerosene which is perfectly
" sweet," may still yield a product of which the colour is
not up to the required standard. The colour may readily
be improved by mixing the kerosene with a small percentage
of some decolorizing powder, and allowing the powder to
settle out or filtering it off. Various decolorizing powders
may be used for this purpose, e.g. animal charcoal, a
bone black, the many varieties of fuller's-earth, e.g. the
American floridin, the German frankonit and so forth.
Certain types of bauxite also function well.
The action of these decolorizing powders is so erratic
that general working rules cannot be laid down. Some
powders in the case of certain kerosenes may act best in their
ordinary air-dried state, some may work better if dried at
105° C., and others only if previously ignited. For any
particular kerosene, powder A may be found better than
B, yet for another type of kerosene, powder B may be
found better than A. It is of the utmost importance,
therefore, to examine thoroughly the effect of the possible
powders on the kerosene in question before beginning
operations.
It will generally be found that the animal charcoals are
TREATMENT OF PETROLEUM OILS 203
much more efficient (per percentage used) than are the
fuller's-earths, but they are usually much too expensive.
As a general rule, also, f tiller 's-earth works better if pre-
viously ignited or at least if previously dried at 105° C.
Many of these fuller's-earths may be regenerated and reused,
as is also the case with bauxite.
In the case of kerosene, the decolorizing powder may be
introduced into the ordinary agitator, and the mixture run
off into a settling tank. In order that the last traces of the
powder may be removed, the kerosene should be filtered
through paper in filter presses, or may be centrifuged by
means of a Gee centrifuge.
The chemical treatment of lubricating oils and waxes
are carried out on similar lines, certain necessary modifica-
tions being introduced.
The treatment of lubricating-oil distillates with sulphuric
acid is usually carried out in an agitator constructed some-
what similarly to that used for kerosene. The agitators
are usually of somewhat smaller capacity, of greater
diameters, and less depth. They may be provided with
steam coils for heating purposes. The agitation is invariably
effected by means of air. I^arge percentages of acid up to
20 per cent, or more may be used, especially for the heavier
oils. After agitation the mixture is usually run out into a
settling tank of large diameter, in which the acid sludge
may more easily separate out. This acid sludge, in the
case of heavier oils, may be practically solid and may
require digging out. The supernatant oil, after thorough
settling, is drawn off and transferred to the soda agitator,
where it is neutralized with white dilute caustic soda with
gentle agitation and then washed. Great care must be
taken with the neutralizing and washing as emulsions may
form, the subsequent splitting up of which may give great
trouble.
The colour and appearance of the finished oil will depend
to a great extent on the thoroughness of the separation
from the acid sludge. Inefficient washing of the soda
treated oil will result in the presence of soaps in the finished
204 PETROLEUM AND ALLIED INDUSTRIES
oil. After thorough washing the oil is usually warmed and
blown dry by passing air through it. This must be done at
a temperature not too high, not exceeding 50° C., otherwise
the oil may go off colour somewhat. Various modifications
of this method have been suggested and are in operation,
e.g. the use of sodium silicate in place of caustic soda, the
use of lime or soda lime for neutralization in place of soda.
A great number of lubricating oils are, however, made
without any acid and soda treatment at all. Such are the
filtered cylinder oils, filtered neutral oils, and many others.
The filtration is effected through one of the decolorizing
powders above mentioned. The operation is simple. The
filtering powder, usually granulated and free from fine
dust, is filled into a vertical cylindrical vessel, resting on
filter cloth supported on horizontal grids. The filtering
vessel is steam jacketed, and fitted with manholes or a
removable bottom for extracting the powder after use.
The heated lubricating oil distillate is allowed to per-
colate upwards through the filtering medium. The first
fractions which pass through may be only slightly coloured,
but the colour grows in depth as filtration proceeds. By
collecting the filtered oil in separate vessels several grades
may be produced. After the filtering has proceeded as far as
is deemed advisable, the vessel is disconnected and allowed
to drain. Benzine is then passed through the vessel in
order to dissolve out the oil adhering to the fuller's-earth,
this benzine being subsequently recovered by distillation,
After thus washing the fuller's-earth, steam is passed through
to remove the last traces of benzine. The vessel is then
opened and the fuller's-earth removed for regeneration.
The behaviour of the fuller's-earth should be investigated
before use in order to find out the best conditions for
use. The decolorizing action of fuller's-earth is doubt-
less a physical one, the asphaltic bodies being absorbed.
Gurwitsch maintains that the fuller's-earth exerts a poly-
merizing action on the unsaturated compounds, an opinion
shared by Hall (vide p. 202).
The method of refining by mixing with decolorizing
TREATMENT OF PETROLEUM OILS 205
powder is also applied to the manufacture of paraffin wax.
This is described in Section D, dealing with that product.
The Edeleanu Process. — The above-mentioned pro-
cesses for the refining of oils apply generally to the removal of
small percentages of constituents (so-called impurities), the
presence of which is considered objectionable. The kerosene
fractions of certain crude oils, notably those of Borneo, and
to a less extent those of Rumania, contain appreciable
quantities of aromatic hydrocarbons, the presence of which
renders the oil of relatively poor burning quality when used
in ordinary lamps. (When, however, burned in lamps of
suitable design such aromatic kerosenes can give excellent
results.)
The problem in refining such oils is, therefore, that of
removing a relatively large percentage of aromatic hydro-
carbons. This could, of course, be done by sulphonation,
but in this case the splitting up of the sulphonic acids formed
and the regeneration of the sulphuric acid, are problems of
great technical difficulty. The process designed by Edeleanu
(U.S. Pat. 911553, Eng. Pat. 11140 of 1908) is a physical
process in which the above-mentioned difficulties do not
appear. This process depends on the use of liquid sulphur
dioxide as a solvent for unsaturated and aromatic hydro-
carbons. Naphthenes and paraffins are relatively insoluble
in this reagent.
The principle of the process is simple. The kerosene
to be treated is agitated with a large volume of liquid
sulphur dioxide at a low temperature, say — 10° C.
Separation into two layers takes place, the lower being
a solution of the aromatic hydrocarbons in liquid sulphur
dioxide, the upper the naphthenes and paraffins, con-
taining some sulphur dioxide in solution. These layers
are separated and the sulphur dioxide is separated off by
distillation, recondensed, and used over again. The sulphur
dioxide works thus in a cycle, so that only working losses
need be made up.
By the Edeleanu process also the sulphur-containing
bodies occurring as impurities may also be removed.
206 PETROLEUM AND ALLIED INDUSTRIES
Several large-scale plants operating by this method have
been erected in Rumania and elsewhere. Edeleanu gives
a full description of the working method in " Bulletin,"
Am. Inst. Min. Eng.t 1914, p. 2313.
The distillate is first dried by passing through filters
filled with dry salt. It is then pumped through a cold
exchanger, where it is cooled by the cold extract issuing
from the mixing vessel. The distillate is then further cooled
by passing through a distillate cooler, where it is cooled by
a separate refrigerating system (not shown in the diagram).
It then passes into the mixing vessel, where it meets the
liquid sulphur dioxide which has likewise been cooled by
E«£ft2£. j..^
FIG. 38. — Working scheme of Edeleanu plant.
the issuing refined product and in a special cooler by means
of a refrigerating system not shown in the diagram.
As the sulphur dioxide is admitted into the mixer, it is
at first completely absorbed by the distillate. After a time,
however, the mixture separates into two layers, the lower
being the extract, a solution of the aromatic hydrocarbons in
liquid sulphur dioxide ; the upper, the unaltered naphthenes
and paraffins, containing some sulphur dioxide in solution,
containing also, naturally, some proportion of aromatics
unextracted, according to the conditions of working.
The extract is drawn off by the extract pump through
the distillate cold exchanger to the extract evaporator,
where it is heated by steam coils (not shown in diagram) ;
the sulphur dioxide is returned to the system through
TREATMENT OF PETROLEUM OILS 207
coolers and dryers, and the extract, now free from sulphur
dioxide, is pumped away.
The refined product is pumped out from the mixer
through a cold exchanger, absorbing heat from the liquid
sulphur dioxide in this case. The refined product then
passes on to its evaporator, where the dissolved sulphur
dioxide is driven off. The heating of the evaporators may
be effected by the exhaust steam from the engine which
drives the pumps and compressors. Only the bare outlines
of the operation of the plant are described above.
In treating a Rumanian distillate of sp. gr. 0*820,
75 per cent, of a refined product of sp. gr. 0*803, an^
25 per cent, of an extract of 0*869 were obtained. The loss
of sulphur dioxide amounted to 0*56 per cent, reckoned
on the distillate treated.
The oils extracted from the sulphur dioxide solution
are very rich in aromatics and may find special applications
as solvents or in other directions, or may be utilized as fuel,
while the treated kerosenes, being free from aromatic hydro-
carbons, are of excellent quality as illuminating oils for use
with the ordinary types of lamp on the market.
GENERAL REFERENCES TO PART VII., SECTION C.
Bacon and Hamor, " American Petroleum Industry." McGraw Hill
Co.
Campbell, " Petroleum Refining." C. Griffin and Co.
Ellis and Meigs, " Gasoline and other Motor Fuels." D. van Nostrand
Co.
SECTION D.— THE MANUFACTURE OF
PARAFFIN WAX AND LUBRICATING OIL
THE starting point for the manufacture of paraffin wax
is the wax distillate obtained by the distillation of paraffin
wax-containing crudes. The operation of the subsequent
processes depends to a very great extent on the character
of this distillate. This distillate is a mixture of wax and
lubricating oil distillate, and both wax and lubricating oils
are made therefrom. Unfortunately the conditions best for
lubricating oil production are not those best for wax produc-
tion, so that usually a compromise must be made, or perhaps
resort may be had to redistillation. The less steam used in
distilling, i.e. the higher the temperature and the greater
the cracking, the more easily crystallizable the wax and
the less viscous the character of the oil and vice versa.
The extent to which the distillation may be carried is
determined almost entirely by the nature of the crude oil.
Some crude oils (e.g. Pennsylvanian) readily give up their
wax on distillation, leaving as residue an oil relatively
wax free. vSuch residues may indeed be used as " steam
refined cylinder stocks." Others leave a residue which
still contains much wax. This residue cannot be distilled
further by the ordinary method employing steam, as the
distillates which would be so obtained would contain high
melting-point wax which would not crystallize or sweat
well, perhaps owing to the highly viscous oil with which it
would be associated. Such residues may be either burnt
as fuel or distilled by the so-called cracking distillation
method, i.e. without steam, right down to coke. As the
paraffin wax existing in the crude oil cannot be separated
208
THE MANUFACTURE OF PARAFFIN WAX 209
off by means of filtration owing to its amorphous condition
the oil must be distilled. The paraffin which distils over is
crystalline and amenable to filtration. The methods adopted
for working up the distillate containing paraffin wax vary
with different crudes and in different refineries. In some
cases the wax distillates are subjected to a sulphuric acid
treatment and perhaps to a redistillation before being
filtered, but in many cases this is not necessary.
In general, the method of extracting the wax adopted
is that of filtering off the wax from the chilled distillate,
and subsequently freeing it from oil by sweating, or by
washing by solvents which dissolve the oil but not the wax,
e.g. alcohol.
The wax distillate is "cut " from the distillation by using
the congealing point as a guide, the points selected being
based on previous works and laboratory experience for the
particular oil.
The chilling of the distillates may be effected in various
types of plant. That in general use in the United States is
continuous in action, viz. the " Carbondale " type. This con-
sists of a number of coolers made up each of two concentric
pipes arranged one over the other horizontally. The wax
distillate is pumped through the internal pipes, each of
which is provided with a worm, passing through the set in
series, while the cold brine is circulated through the annular
spaces in counter-current fashion.
The cold brine is produced by one of the well-known
types of refrigerating plant, usually with ammonia as working
fluid. For details of the operation of such a plant the
reader must be referred to standard works on refrigerating
practice. The degree to which the wax distillate .is cooled
must depend on its wax content. If the wax content be
high the operation may best be conducted in two or even
three stages. In such a case the chilled distillate would be
filtered, and the filtered oil further chilled ; if the chilling
were completely effected in one stage the chilled distillate
might be too thick to handle.
As the formation of well-defined crystals is of importance
p. 14
210 PETROLEUM AND ALLIED INDUSTRIES
because of the subsequent operations, and as the size of
the crystals depends, not only on the material, but on the
conditions of cooling, other types of cooler may be found
more satisfactory in certain cases. A well-known type is
the "Henderson" (Fig. 39). This is composed of a large
rectangular vessel, which may have a capacity of 10 tons or
more, divided up into a number of narrow compartments
by hollow plates through which the cold brine circulates.
A central shaft carrying scrapers very slowly revolves,
scraping away the wax as it crystallizes on the surfaces of
the hollow plates. A stirrer working in a channel along the
bottom enables the pasty mass to be transferred to the
suction of the pump. In another type of somewhat similar
design, no scrapers are employed, so that the cooling is very
slow. The dividing plates are in this case made tapering in
section, so as to allow of the easy removal of the semi-solid
mass.
The chilled wax distillate is then passed on by pumps
to the filter-presses. These filter-presses are of the normal
type, sometimes with square plates, more often with circular.
The presses used in America are of massive construction —
48 inches in diameter with 300 plates. These presses are fitted
with hydraulic ends for closing the press tight, as pressures
up to 300 Ibs. to the square inch are sometimes employed
in filtering the wax. Numbers of these presses are housed
in one building, which must be kept cool and well insulated.
It is usual to maintain the temperature in the filter-presses
a degree or two above that of the chilled wax distillate, in
order to ensure that no crystallization takes place in the
presses (as this would tend to clog the filter- cloths).
When any one press is full and has been pumped up to
full pressure, the supply of chilled distillate (which may be
called by the convenient Galician term " gatsch ") is cut off
and the press is opened. The filter cakes fall out into a
conveyer placed beneath the press and are conveyed to a
melting-up tank outside the building.
In this way the wax distillate is separated into a " slack
wax " filter cake and filter oil, this filter oil being naturally
THE MANUFACTURE OF PARAFFIN WAX 211
212 PETROLEUM AND ALLIED INDUSTRIES
saturated with wax at the temperature of filtration. The
slack wax may amount to about 20 per cent, of the gatsch
pumped through the press.
The filter oil or pressed distillate, if from a first-stage
chilling, is rechilled and refiltered, thus yielding another
batch of filter cake of lower melting point ; if from a final
chilling it is reduced or concentrated in stills to the required
viscosity to yield a lubricating oil.
The slack wax or filter cake is then melted up and pumped
to the sweating house, where it is subjected to the sweating
process.
Sweating is a process of fractional melting. The opera-
tion is carried out in sweating pans, erected in a sweating
house. The sweating pans are shallow sheet-iron trays,
5 or 6 inches deep, fitted with false bottoms of coarse
wire gauze. The bottom of the tray slopes from all sides
toward the centre, from which point a draw-off pipe leads
to a main draw-off pipe, passing to the outside of the house.
Immediately beneath the wire gauze false bottoms lie a
number of perforated steam pipes and just above the gauze
are sometimes fixed a number of f-inch pipes, through which
cooling water may be circulated.
The trays are first partly filled with water covering
the gauze false bottoms. Melted slack wax is then floated
on to the surface of the water until it forms a layer 3 to 4
inches thick and is then allowed to cool. When the wax has
solidified, the water is run off, the cake of wax being thus
allowed to rest on the gauze false bottom.
The house, containing a number of such trays, fitted up
one above the other, is then closed up and slowly warmed by
means of exhaust steam through steam pipes placed on the
walls. As the temperature rises, sweating starts, the oil
oozes out of the fine network of crystals, accompanied of
course by much low melting-point wax. The process is
controlled by watching the character of the wax flowing
off and by examining the product as it lies on the
trays.
When the process is judged to be complete, the wax
THE MANUFACTURE OF PARAFFIN WAX 213
lying on the trays being oil-free and of the correct melting
point, the temperature of the house is quickly raised and live
steam is blown in through the perforated pipes, so that the
sweated wax on the trays is melted up, the effluent pipes
being then diverted to the sweated wax tanks.
The slack wax is thus split up into sweated wax (which
is now free from oil) and " foots oil " and " foots wax."
The " foots wax " is resweated to yield wax of lower melting
point, or it may be in part returned to the cool-house or
even to the distilling bench.
The process of sweating is slow, usually taking from
24 to 60 hours according to the nature of the wax. The
above-described apparatus, which is that in most genera;!
use, was first devised by Henderson in Scotland. A notice-
able improvement is that patented by Pijzel. The sweating
stoves are made movable so as to run on rails. The
sweating house consists of a long tunnel heated by hot
air, with a melting-out chamber at one end. The sweating
pans enter at one end and are transferred through the tunnel
by a series of stages as each finished stove is melted out.
The considerable waste of heat involved in alternately
cooling and heating the sweating house is thus avoided.
The actual control of the operation and the working
details depend on many factors and must be worked out for
each particular plant. Generally, several grades of wax
of melting points say about 122°, 127°, 132°, and 140° F.
will be made and perhaps, also, a very soft match-impreg-
nating wax too.
The sweated wax should now be free from mineral oil,
but will still contain some colouring matter. This may be
removed either by refining or by filtration.
If the refining process be used the melted paraffin wax
is agitated with a small percentage of concentrated sulphuric
acid. The acid sludge is drawn off and the melted wax
is then run down into a powder mixer. This is a cylin-
drical horizontal vessel fitted with paddles. In this vessel
the wax, kept hot by means of steam coils, is agitated
with a decolorizing powder, such as animal charcoal,
214 PETROLEUM AND ALLIED INDUSTRIES
potassium ferro-cyanide waste, some type of fullers-earth or
bauxite.
When the treatment is complete the whole is blown by
compressed air through a cloth filter-press, to remove the
bulk of the decolorizing powder, the last traces being
removed by filtering through paper in a filter-press fitted
with steam- jacketed plates.
Instead of treatment with acid and decolorizing powder,
a filtration treatment may be adopted. The filter used is
made of a vertical cylindrical steam- jacketed vessel, which
may have a capacity of i ton or more of filtering medium.
It is constructed with a removable bottom, so that the
exhausted decolorizing powder may be removed. The
melted wax is allowed to percolate through the filtering
medium, which may be a fuller's-earth such as floridin, an
animal charcoal or bauxite (Eng. Pat. 16617 of 1908).
The filtering medium must not be too finely divided, other-
wise filtration is too slow. It is usually ground to the
fineness of coarse gunpowder. In some cases decolorizing
powders act best after drying at 105° C., in some cases best
after ignition. This point must be settled by experiment in
the laboratory. As the wax filters through, the discolora-
tion is removed, but as the powder loses its efficacy the
issuing wax will begin to show a yellowish tint. At a
certain point, therefore, the filtration must be stopped and the
filter drained. The exhausted filtering medium is then
removed and a fresh charge put in. After filtration the wax
is finally filtered through filter-presses with paper, and is
then run off into moulds and allowed to cool. It may also
be cooled by being allowed to flow in a thin film on to the
surface of a rotating cylinder cooled internally by water,
from the surface of wrhich it is peeled off by a fixed knife-
edge and packed directly into barrels.
The actual details of the method to be employed in
working up any particular crude for wax must depend upon
the crude itself and upon local conditions.
The paraffin wax crudes of the United States of America,
contain, as a rule, about 2 to 3 per cent, of wax, Galician oils
THE MANUFACTURE OF PARAFFIN WAX 215
about 5 to 6 per cent., while some of the oils of Burmah and
Borneo contain up to 10 per cent., or more.
As an example the following scheme of working up a
crude oil may be given : —
This crude yielded on distillation —
Crude benzine . . . . 14 per cent.
,, kerosene . . . . 41 „
Gas oil 3
Wax distillate . . . . 37 „
Coke . . .... . . 3
The wax distillate was worked up in the manner set out
diagrammatically below.
WAX D/5T/LL.ATC.
/>O//VT- */ c.
ro~fo*c
r
eovcenTffinfo at
!j
7-«0.
C/i.
r
OffCC SWCATCO
I !
wJut. AOO»
WAX JoX.
tejLm.
_l_
v/L .c-
x^^
1
^^S,
.i,
"^*r™
LJ.v*
FIG. 40.— Scheme for operating a wax plant making one grade of wax only.
This represents an ideally simple case. In many cases
several grades of wax of different melting points are
made.
Variations of the method are innumerable and must be
216 PETROLEUM AND ALLIED INDUSTRIES
worked out to suit each case. In some cases the foots oil
is returned to the cool-house for rechilling, in others it is
redistilled, in some cases it may be pumped to liquid fuel.
Paraffin wax is also extracted from materials other than
crude petroleums. The shale oils of Scotland, for example,
yield about 2 per cent, of rather low melting point (45/46° C.)
wax. The shale oils of New South Wales also yield paraffin
wax, as do in general most shale oils. Tars from the distilla-
tion of wood, especially beech, also yield paraffin wax ; in
fact, this is the material from which paraffin wax was first
made. Lignite and the peculiar mineral substance pyro-
pissite (vide p. 151) are worked up in Germany and yield
considerable quantities of paraffin wax, as distinct from
the montan wax already alluded to (vide p. 150). As, in
the case of such tars produced by distillation, the paraffin
wax exists in the crystalline form, it can be directl)7 separated
from the tar, topped to remove the lighter fractions, by the
usual crystallizing method.
Several processes of extracting paraffin wax depending
on the relative solubilities of wax and mineral oils in various
solvents, e.g. alcohol of various strengths, acetone, ethyl
acetate, etc., have been devised (e.g. German Pats. 123101,
140546, and 149347), but these methods are not used to
any extent. Alcohol will dissolve all the oils, resins, and
creosotes present in such tars. The tar is dissolved in ten
times its weight of 90 per cent, alcohol in an autoclave at
80° C. and the solution cooled. The paraffin wax crystallizes
out and may be separated off by centrifuging.
The manufacture of lubricating oil is intimately con-
nected with that of paraffin wax, as in many cases lubricating
oils are made from the oils resulting from the filtering off
of the wax from wax distillates. Lubricating oils are also
manufactured from naphthenic or asphalt base oils, in which
case the removal of wax by filtration is unnecessary.
It is often held, though by no means proved, that
lubricating oils derived from paraffin wax base oils are
of better quality than those derived from naphthenic or
asphalt base crudes.
MANUFACTURED OF LUBRICATING OIL 217
Lubricating oils may be divided roughly into two
classes, residual and distillate oils. Residual oils are those
which result from the concentrating down by distillation of
certain types of crude oil. A naphthenic oil free from
paraffin and not rich in asphaltic material may be concen-
trated down to make a low-grade black oil, such as an
axle oil, which need not have a high flash-point or good
colour. Such oils may also be used for the manufacture
of dark greases.
Certain types of paraffin-wax-bearing crude oil of the
Appalachian fields yield as a residue after the other products,
including the wax, have been distilled off, a so-called " steam-
refined cylinder stock." The distillation is carefully carried
out at as low a temperature as possible (preferably in vacuo)
with ample steam. The distillation is carried on until the
flash-point of the residue rises to from 500° F. to 700° F. ;
600° F. steam refined stock being the grade in general use.
With these crudes the asphaltene content is so low that
these residues, which have exceptionally high flash-points,
may be used as cylinder oils for steam cylinder lubrication.
With other types of crude oils the residues so produced would
contain too much wax, or be too rich in asphaltenes, or have
too low a flash-point, and so be of relatively inferior quality.
These steam-refined cylinder stocks may be filtered through
decolorizing powders or animal charcoal, the asphaltenes
being thus removed, so that a fine-looking oil, reddish-brown
by transmitted, green by reflected, light results. Such
oils are known as "filtered cylinder oils," and are much
valued as such and for blending purposes. Such filtered
cylinder oils may, however, still contain a little paraffin
wax. This may be removed by dissolving the oil in light
benzine, chilling the mixture, and removing the separated
wax by means of a Sharpies centrifugal machine ; the
benzine is then distilled off and a filtered cylinder bright
stock then remains.
Similar cylinder oils may be manufactured by the
concentration of lubricating oil distillates. Russian crudes,
for example, may be distilled down to " astatki," or thick
218 PETROLEUM AND ALLIED INDUSTRIES
fuel oil, lubricating- oil distillates being produced. These
lubricating-oil distillates may be concentrated down to
cylinder oils of flash-point about 400° F.
This concentration is carried out in an ordinary fire-
heated still, the temperature being kept down as low as
possible by means of copious use of steam. The distilla-
tion or " reducing " is carried on until the tests of the residue
have the required values. This reduction is best effected
in vacuo, the quality of both distillates and reduced stock
being thus improved.
The lighter varieties of mineral lubricating oils are all
distillates which may or may not have been reduced to grade
by concentration, or which may be straight distillates, or
perhaps blends of several distillates.
The material used may be either a distillate from riaph-
thene base crude oils, such as those of Russia, Texas, and
California, or a filtered " press oil " obtained by filtering
off the paraffin wax from a well-cooled wax distillate obtained
from wax or mixed base crude oils, e.g. certain of those of
Pennsylvania or Mid-continent fields.
When the distillates have been distilled or concentrated
to the required viscosity, they must be refined. In some
cases these oils are refined before pressing out the wax, in
other cases the refining is the last treatment to which they
are subjected.
In United States practice the lighter wax distillates are
called " neutral oils " or " spindle distillates."
The pressed distillate after reducing to grade is filtered
through a decolorizing medium, and does not receive an
acid treatment. The resulting oil is termed a " neutral
oil." Such neutral oils may be termed " non- viscous " or
" viscous " according to their viscosity.
The chemical treatment of lubricating oil by means
of sulphuric acid is carried out in agitators of the usual type,
the temperature of the oil being kept as low as conveniently
possible in regard to fluidity.
In order to economize plant the settling out of the
acid sludge is usually allowed to take place slowly in shallow
MANUFACTURE OF LUBRICATING OIL 219
settling tanks of large diameter. When the acid sludge has
settled out completely the oil is transferred to the soda
agitators, where it is gently warmed and neutralized with
caustic soda, being subsequently well washed by sprays of
water, and finally dried by the blowing through of air. The
process of refining of lubricating oils, particularly the
neutralizing and washing, is difficult, as emulsions often
form with great readiness, and these may be difficult to
split up.
The splitting of such emulsions is usually effected by
the addition of dilute acid, and subsequent re-treatment
by soda after good settling out of the dilute acid layer.
The addition of small quantities of oleic acid during the soda
treatment may also assist in preventing the emulsification,
and the addition of salt water may sometimes break up an
emulsion once formed.
Sodium silicate in a solution of specific gravity about
30 Be. may also be used in place of soda, the precipi-
tated silica perhaps assisting by carrying down impurities
mechanically.
Many other methods of refining have been proposed
for which vide Engler-Hofer, " Das Erdol," vol. 3, pp. 522,
527.
No general rules can be laid down, as the detailed method
of treatment of any oil depends on the nature of the oil.
The losses incurred by refining in this way are high,
amounting to as much as 20 per cent, or more in particular
cases.
As the general plan of the working up of a shale oil into
wax and lubricating oils may be more complicated than that
of a petroleum crude, a scheme of working up a Scotch shale
oil (vide " The Oil Shales of the Lothians," Mem. Geol.
Survey, Scotland) is herewith given : —
220 PETROLEUM AND ALLIED INDUSTRIES
ctf <i>
a .22
VH
4) C}
O
41
!
-?l
T3
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-S-
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o
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rt o
Si o
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a
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o r^-5
c °
MANUFACTURE OF LUBRICATING OIL 221
It must be again emphasized, however, that every oil
to be worked up must be treated on its own merits, and
the best method for that particular case must be devised.
The various grades of mineral lubricating oil made and
their properties will be described under the section dealing
with applications of petroleum products.
"Perotlatum," also known as petroleum jelly, petroleum
ointment and vaseline (the trade name of the well-known
product made by the Cheeseborough Co.), is a product
defined in the United vStates pharmacopoeia as " a mixture
of hydrocarbons chiefly of the methane series obtained by
distilling off the lighter and more volatile portions from
petroleum and filtering the residue."
It may be prepared from the residues from the distilla-
tion of certain paraffin wax base crude petroleums, the
concentration being carried to the necessary extent. Many
paraffin-rich crudes will, however, not yield a suitable
product. It may also be made from the " rod wax " which
accumulates in the pumps of certain wax crude wells (Mabery,
Proc. Am. Acad., 1904, p. 349), and from the bottom settlings
(B.S.) of the same type of oil.
The residues or " reduced oils " from certain cnides are
filtered through animal charcoal or some form of fuller's-
earth in steam-jacketed filters, the first runnings being
collected and steamed to remove any earthy smell due to
the fuller 's-earth. The rod wax or crude oil B.S. may
be similarly distilled to the right concentration and then
filtered.
Another variety of petrolatum is made by the addition
of paraffin wax of low melting point to lubricating oils
filtered to a fine colour. Such petrolatums are, however,
not so homogeneous and separate out crystalline paraffin.
Liquid Petroleum or Medicinal Oil is a product
which is to all intents and purposes a highly refined lubri-
cating oil. Oil of a suitable viscosity is treated with suc-
cessive treatments of oleum, neutralized and filtered through
f uller's-earth. The treatment is very drastic and the refining
losses very heavy. The product is quite odourless, tasteless,
222 PETROLEUM AND ALLIED INDUSTRIES
and colourless. The hydrocarbons which are present in
petrolatums are all undoubtedly of a saturated type. In
the types of petroleum derived from residue no crystalline
hydrocarbons are present, the solid members being probably
similar to those found in ozokerite or natural mineral wax.
Lubricating Greases. — These are made in great
variety, a petroleum oil forming the basis of the majority.
They are composed in the main of two constituents, a soap
and an oil, the soap usually being formed during the manu-
facture of the grease. Calcium and sodium soaps are
generally used, but certain greases contain potassium and
aluminium soaps. Moreover, some greases contain fillers
such as graphite, French chalk, mica, etc. Many varieties
of oils and fats are used, such as palm oil, tallow, resin oil,
anthracene oil, and petroleum residual oils.
The plant used for the manufacture of greases is simple,
consisting merely of (a) a melting and boiling pot for melting
up or heating the fat or oil, (b) a mixing vessel with steam-
jacketed walls and arrangements for stirring. The con-
stituents of the grease are introduced into the boiling pot
and heated for several hours, the contents then being run
down into the mixing vessel, where they are thoroughly
incorporated. Fats proper or fatty acids may be used for
grease making, in the former case the glycerin remaining
in the grease.
A cup or motor grease may be made by the incorporation
of about 6 per cent, of hard tallow soap into an engine oil,
or alternately by boiling up tallow, and finely divided slaked
lime free from grit with the necessary proportions of the
selected mineral lubricating oil.
The so-called 4< fibre greases " are made by using caustic
soda in place of lime. " Rosin greases " are made by boiling
lime with rosin oils ; " black greases " by the use of mineral
residual oils. A product termed " mineral castor oil," which
contains an aluminium soap, is used for the lubrication of
agricultural machinery. A soap stock is made by making first
a sodium soap and treating this with alum solution. The
aluminium soap is then dissolved in a quantity of mineral oil
MANUFACTURE OF LUBRICATING OIL 223
and the clear soap stock so obtained is mixed into further
quantities of mineral lubricating oil to make the various
grades of " mineral castor " required. Innumerable types of
greases are manufactured and sold ; an enumeration of the
various formulae used for compounding would serve no good
purpose here.
Cutting Oils. — A special product which should have good
lubricating properties and a high specific heat is required
for lubricating cutting and drilling tools, as an important
function of such a lubricant is the cooling of the cutting
edge. The so-called water soluble oils are, therefore, largely
used for this purpose. Water soluble oils are usually
mineral oils held in suspension by soaps, alkalies, or sulphon-
ated oils. These oils should be readily miscible and form a
stable emulsion with water so that they may be circulated
and used over and over again.
Oleic acid is saponified with soda, the solution concen-
trated and mixed with alcohol, and then with a mineral
oil. The naphthenic acids extracted during the refining
of mineral oils may be used for the purpose of making the
soaps for these soluble oils. Sulphonated castor oils are
also used for this purpose.
GENERAL REFERENCES TO PART VII., SECTION D.
Bacon and Hamor, " The American Petroleum Industry," vol. 2.
McGraw Hill Publishing Co.
Battle, " Industrial Oil Engineering," vol. I. C. Griffin and Co.
Campbell and Wilson, J.I.P.T., 1919, p. 106.
Engler-Hofer, " Das Erdol," vol. 3. Hirzel, Leipzig.
Gregorius, " Mineral Waxes." Scott, Greenwood and Co.
Hurst, " Lubricating Oils, Fats, and Greases." Scott, Greenwood
and Co.
SECTION E.— THE MANUFACTURE OF FUEL
OILS, RESIDUAL OILS, AND ASPHALTS
FROM CRUDE PETROLEUMS
THE manufacture of fuel oils from various crudes is a
comparatively simple operation, the modus operandi depend-
ing on the nature of the crude oil and the type of fuel oil to
be produced. There are a number of crude oils, particularly
of the naphthene base type, which yield a residual fuel oil,
of low viscosity after the distillation off of the benzine and
kerosene fractions.
Such fuel oils may be of low cold test, liquid at tem-
peratures well below o° C. These oils easily fulfil the
conditions of the British Admiralty specification and may
in many cases be used as diesel oils even for marine
engines.
Crude oils of other types which contain asphalt in greater
quantity yield, as a residue after distillation off of the
benzine and kerosene fractions, a fuel oil of greater viscosity
and higher cold test. Such an oil, while a perfectly satis-
factory fuel, may not conform to Admiralty specification.
Other crudes, e.g. the asphaltic crudes of Mexico, after only
the benzine fractions have been topped off, yield a residue
which is too viscous for use as fuel without special heating
and burning arrangements. Such crude oils are, however,
valuable as sources of asphalt.
In distilling such crudes down to asphalts of the required
specification, quantities of gas oil distillate are obtained,
which distillate may be used directly as a diesel fuel oil, or
as a diluent for thinning down supplies of a too thick fuel
oil. Other types of crude oil yield a wax residue which may
be distilled to coke in a coking still, yielding wax distillate
224
THE MANUFACTURE OF FUEL OILS 225
and wax tailings, which, on filtration, yield an oil which may
be used as fuel.
Fuel oils may thus be divided into two categories —
(a) distilled fuel oils, i.e. gas or solar oils, which being
distillates are free from any residual asphalt, and which
therefore form high-class oils for diesel and semi-diesel
engines, and which may be used as a basic material for
cracking — either to gas for enriching illuminating gas, or to
motor spirits (vide Section F) ; and (b) residual fuel oils
which may be used for diesel engine fuels in some cases, and
as furnace oils in all cases.
Of similar nature are the residual oils used for road
spraying (road oils), and those used for thinning down
asphalts (flux oils), which are merely residual oils which
must conform to certain specifications as regards viscosity,
flash-point, etc., and which, therefore, must be made from
certain selected crudes. The manufacture of all such oils
may be carried out in the ordinary type of still, or in a
plant of the tubular retort type, it being merely a question
of distilling off sufficient distillate to obtain a residue of the
required character.
Asphalts are manufactured from certain types of crude
oil which contain little or no paraifin wax. Certain crudes
which are free from wax contain, however, little asphalt,
and may thus best be used for liquid fuel manufacture.
Most native asphalts are much too hard for most purposes,
particularly for road work, and so must be softened by the
addition of flux oil. Asphalts made from certain types of
crude petroleum can, however, be made to any degree of
hardness by controlling the distilling process.
The best asphalts are produced from certain crude oils
of Mexico and California. Certain crudes of Texas,
Venezuela, Trinidad, and elsewhere also yield good asphalts.
The process of manufacture consists in distilling down
to the required concentration under certain conditions.
To obtain the best qualities of asphalt, the avoiding of
cracking is necessary ; consequently distillation to asphalt
is always carried out with the assistance of copious supplies
P. 15
226 PETROLEUM AND ALLIED INDUSTRIES
of steam blown into the still during distillation, the distilling
temperature being kept thus as low as possible.
This distillation is usually conducted in very large stills;
worked periodically ; it may also be carried out in a con-
tinuous bench of stills, the control being effected by
examination of the residue rather than ' of the distillate.
The distillates may be gas or lubricating oils, according to
the grade of asphalt which is being made. An objection to
this mode of distillation is the length of time to which the
asphalt is subjected to a high temperature.
It may also be made by one of the topping-plant type of
tubular stills. In this case the asphalt is subjected to the
necessary temperature for distillation for a very much
shorter period. Overheating of an asphalt during manu-
facture is indicated by the difference in solubility in carbon
bisulphide and carbon tetrachloride. This difference for a
well-made asphalt should not exceed 0-5 per cent.
The temperature of distillation may also be kept down
by distilling in a high vacuum plant, a method which produces
asphalts of very good quality.
The grade of asphalt is usually defined by the penetration
test, i.e. the depth to which a standard needle (No. 2 sewing
needle) under a load of 100 grammes will sink into the asphalt
at a definite temperature (77° F.) in 5 seconds. Grades of
penetration varying from 200 to 40 are usually made for
road work. Harder asphalts are also sometimes made for
certain purposes.
Blown Asphalts. — I/arge quantities of asphalt are also
made by the blowing process. As far back as 1865 it was
known that asphaltic substances were susceptible to the
action of oxidizing agents, which produced products of
greater viscosity. In 1894 a patent was granted to Byerley
for " blowing " petroleum residual oils by means of air.
The action which takes place appears to be a condensation,
hydrogen being removed from two molecules as water, the
molecules then condensing up.
The blowing process is carried out in large stills, the
larger, the easier the control. The oil or asphalt to be
THE MANUFACTURE OF ASPHALTS 227
blown is heated up to a temperature between 200° and
230° C. Copious supplies of air are introduced by
means of a large number of perforated pipes placed in the
bottom of the still. As the oxidation proceeds, sufficient
heat is developed to render external heating necessary ;
indeed, care must be exercised to prevent the temperature
rising too high. As the oxidation proceeds the melting
point of the asphalt rises, the penetration decreases, and
the ductility falls off very rapidly. In this way heavy road
oils or liquid asphalts may be blown to asphalts of high
melting point. These asphalts, if produced from a
moderately hard asphalt to start with, may be brittle and
hard ; if produced from a liquid asphalt containing much
oil, may be tough, pliable, and leathery in nature. The
qualit}' of the blown asphalt may thus be varied considerably
by varying the basic material, and to some extent also by
varying the conditions of blowing.
During the blowing process, vapours are given off which
may be condensed and used as fuel oil.
The blowing process has several advantages : —
(1) The yield of asphalt from a given petroleum residual
oil is greater than that obtained by distillation methods.
(2) Certain crudes which would yield little or no asphalt
by distillation will yield asphalts of good quality by blowing.
Naturally, the more asphaltic the nature of the crude the
less blowing necessary.
(3) Blown Asphalts are less susceptible to temperature
changes than are those made by distillation. The process,
however, is of longer duration. Much care must be taken
in the manufacture of blown asphalts, particularly when they
are made from crudes poor in asphalt. When made from
mixed base petroleums they are likely to present a greasy
surface, owing to the presence of paraffin wax. In general,
blown asphalts are characterized by lack of ductility, and
if overblown, or blown at too high a temperature, they will
contain excess of carbenes and even free carbon. The
fusing point of a blown asphalt will generally be found to be
higher than that of a residual asphalt of the same penetra-
228 PETROLEUM AND ALLIED INDUSTRIES
tion. The subject of blown asphalts is treated in detail in
Abrahams' book on "Asphalts and Allied Substances/'
p. 287 (D. van Nostrand Co.).
Vulcanized or Sulphurized Asphalts may be made by
treating with sulphur, the sulphur apparently affecting the
condensation (with liberation of sulphuretted hydrogen)
just as does oxygen. The product is similar in character to
an air-blown asphalt.
Sludge asphalts may be obtained from the sludge acids
resulting from the treatment of kerosenes and lubricating
oils. These sludges are boiled with water until all the acid
separates and leaves a heavy residuum. This is then
washed with water and heated to the required consistency
by the injection of superheated steam. Sludge asphalts are
characterized by a high content of sulphur and oxygen, and
high solubility in aromatic free petroleum spirit (sp. gr.
0*645). They do not withstand the weather as well as do
the blown and residual asphalts, and are at present of
comparatively little importance.
There are many other varieties of asphalt of minor
importance, such as wurtzilite asphalt or kapak, which is
made by the distillation of wurtzilite under pressure. This
is characterized by high melting point and great toughness,
being somewhat similar to blown asphalts.
A great variety of somewhat similar bodies, properly
termed " pitches," are manufactured by the distillation of
such substances as stearine, cotton seed, wool grease, etc.,
being obtained as by-products from the refining of vegetable
oils and greases, etc., a description of which lies beyond the
scope of this book.
GENERAL REFERENCES TO PART VII., SECTION E.
Abrahams, " Asphalts and Allied Substances." D. van Nostrand Co.
Kohler and Graefe, " Natiirliche und kiinstliche Asphalte." Vieweg
und Sohn.
SECTION F.— CRACKING AND HYDRO-
GENATING PROCESSES
THE extraordinary rapid growth of the automobile industry
has given rise to a constantly increasing demand for benzine,
which, so far, has been met by the petroleum industry.
The motor spirit of twenty years ago consisted almost
entirely of the most volatile fractions of crude oil. Products
boiling completely below 120° C. were common. As the
demand increased, and as carburettors were improved, the
volatility of the benzine decreased. In consequence of the
great demand present-day motor spirits are much less
volatile and include fractions of higher boiling point. Final
boiling points of 220° C. are not uncommon ; indeed, in the
United States of America benzines of final boiling point
230° C., or even higher, are on the market.
It has long been realized that, by the ordinary means of
distillation, a sufficient yield of benzine cannot possibly be
obtained in the future from the available supplies of crude
oils. Efforts have consequently been made to increase
the yield by resort to cracking methods, i.e. methods of
converting hydrocarbons of high boiling point into those of
low boiling point.
As far back as 1861 an American stillman accidentally
noticed that high boiling-point hydrocarbons, at high
temperatures, e.g. when distilling without steam, cracked,
yielding hydrocarbons of lower boiling point. In 1863
Breitenlohner passed the vapours of heavy mineral oils
through red-hot tubes, obtaining volatile oils, hydrogen,
and coke. In 1865 Young took out a patent (Eng. Pat,
3345 of 1865) for increasing the yield of burning oil by
distilling under pressure. In 1866 Vincent, Richards and
229
230 PETROLEUM AND ALLIED INDUSTRIES
others (Eng. Pat. 616 of 1866) patented a process by which
the vapours partly condensed and dropped back into the
hot residue, thus facilitating cracking. In 1871 Thorpe
and Young (Proc. Roy. Soc., vol. 19, p. 370, vol. 20, p. 488,
vol. 21, p. 184) described the formation of hydrocarbons
of the paraffin and olefme series, by heating paraffin wax
under pressure. In 1889 Redwood and Dewar (Eng. Pat.
10277 °* 1889, 13016 of 1890, 5971 of 1891) patented a
process for cracking by distilling and condensing the vapours
under pressure.
Since that time, hundreds, even thousands, of patents
have been granted for cracking processes of one kind or
another, a fact which indicates the importance of the
subject. The fact that up to the present no really satis-
factory cracking process has been devised indicates the
difficulty of the problem.
The theoretical side of the subject has been by no means
completely investigated. The factors influencing the crack-
ing of any particular heavy oil must be numerous, and their
study complicated by the difficulty of getting any informa-
tion as to the chemical nature of hydrocarbons of high
boiling point. The number of bodies taking part in the
reaction may be great, as also the number of bodies
formed.
In general, cracking may be said to be a splitting up of
complex molecules, or a reaction between complex molecules,
of such a nature that simpler molecules and also more
complex molecules are formed. As the percentage of
hydrogen in the molecules of low molecular weight is higher
than in the molecules of high molecular weight, the forma-
tion of low molecular weight molecules must be accompanied
either by liberation of carbon, or by formation of molecules
of higher molecular weight.
The chief difficulty in most cracking processes is indeed
the separating out of solid carbon which clogs up the plant.
It is quite open to doubt how far this material is really
carbon, how far it is really composed of carbon compounds
of high molecular weight.
CRACKING PROCESSES 231
The reactions are further complicated by the fact that
unsaturated hydrocarbons and even hydrogen are often
formed. The temperature at which noticeable cracking
takes place depends on the nature of the oil, and the influence
of the temperature on the rate of cracking is very marked.
F. W. Padgett (Chem. and Met. Eng., 1920, p. 521)
gives the following data showing the influence of tempera-
ture on the cracking of paraffin wax : —
Temperature in still in ° C. . . 417 432 437
Illuminating oil produced % . . 25*4 37*0 33-5
Hydrogen produced % . . . . 0*3 0*9 3*0
Saturated hydrocarbons produced % 74*3 62*1 63*5
By slight changes in the working temperature the
character of the cracking may be considerably altered.
Standinger, Endle, and Herold (Ber., 46, p. 2466), and
Zanetti (J. Ind. and Eng. Chem., vol. 8, p. 20) among others,
investigated the effect of temperature in the case of particular
hydrocarbons. As a general rule it may be taken that
(i) temperatures up to 500-600° C. yield chiefly mixtures of
paraffins and olefines; (2) temperatures about 700° C. yield
defines, diolefines, and aromatic hydrocarbons with smaller
quantities of paraffins ; (3) temperatures about 1000° C.
yield permanent gases and heavy oils rich in aromatic
hydrocarbons.
Pressure is another important factor, the general effect
of pressure being to enable reactions to take place at lower
temperatures, especially reactions of the nature of polymeri-
zation.
As a general rule the unsaturated hydrocarbons and the
paraffins are least stable towards heat, the aromatics most
so. Padgett (loc. cii.} suggests the following t}^pe reactions: —
(1) R-CH2-CH2-CH2-R->R-CH=CH-CH3+RH
(2) R-CH2-CH2-CH3->RH+CH2=CH2+C+H2
(3) R-CH2-CH2-R->RCH3+C+RH
As olefines doubtless occur in many crudes, particularly
232 PETROLEUM AND ALLIED INDUSTRIES
in the fractions of high boiling point, the following type of
reaction may occur : —
(4) R-CH=CH2->RCH3+C.
Olefines may also crack in this way —
R-CH2-CH2-CH=CH-RH>RCH=CH-CH=CH2+RH
yielding diolefines, a class of hydrocarbons which are
certainly present in many cracked distillates.
Further, at high temperatures particular reactions which
give rise to the formation of aromatic hydrocarbons take
place, as exemplified in the cracking processes of Hall and
of Rittman.
The real problem awaiting solution is the conversion of
heavy asphaltic residues into volatile products. So far
only the cracking of heavy distillates, such as gas oil, has
met with any measure of commercial success. The forma-
tion of coke when cracking such a distillate is naturally less
than would be the case if a residue were cracked.
The chief difficulty in the way of commercial cracking
is this formation of coke. The coke deposits on some part
of the surface through which the heat is transmitted to the
oil, and this gives rise to overheating of the metal in this
place, with its consequent burning through. Should this
happen in the case of a plant under pressure a disastrous
accident may ensue.
Cracking processes may be divided into the following
classes : —
(a) Distillation without steam at ordinary pressures.
(b) Distillation or heating under pressure.
(c) Heating the oil in the vapour phase.
(d) Hydrogenating methods.
(e) Various other methods.
(a) A mild form of cracking by carrying out the distilla-
tion of crude oil without the assistance of steam is in
everyday use. In the case of certain crude oils an increased
yield of illuminating oils is so obtained. In distilling for
paraffin wax, a less viscous distillate is obtained by distilling
CRACKING PROCESSES 233
without steam. This is due to slight cracking. Even in
the ordinary processes of distilling lubricating oils with
steam a slight yield of low-flash distillate is obtained.
When distilling certain mixed base oils down to coke in the
usual refinery practice considerable cracking takes place.
This is also the case when distilling crude oils derived from
the distillation of shale. In fact, it is the rule that a certain
amount of cracking cannot be avoided, however carefully
distillation be conducted.
(b) Distillation in the Liquid Phase under Pressure.
— As above mentioned, numerous patents have been taken
out, but few of these processes have found any technical
application.
The Burton process is very extensively used in the
United States, gas oil being the basic substance usually
treated. This gas oil is distilled in a cylindrical still under
a pressure of 4 to 5 atmospheres and the distillates are
condensed under the pressure generated in the still (U.S.
Pat. 1049667, January 7, 1913). The operation is carried
out in a still of the ordinary type, specially strengthened to
withstand the internal pressure. The vapours are led to
an ordinary condenser the outlets from which are closed by
valves, so that the condensation takes place under pressure.
The product obtained has a decided odour and is of a light
yellow colour, which can be removed by refining. It is
claimed that by working at this pressure the product consists
largely of paraffin hydrocarbons. If the condensation is
not carried out under pressure, considerable quantities of
olefines are found in the distillate.
Other processes have been designed, operating with
tubular stills and retorts. These have the advantage that
relatively small quantities of oil are in the plant at one time.
Fleming uses a vertical still, claiming that coke deposits
much less readily on vertical walls. Many devices for
protecting the bottoms of cracking stills have been devised,
e.g. that of Coast (U.S. Pat. 1345134 of June 29, 1920) in
which a protective layer of molten alloy kept in circulation
is used.
234 PETROLEUM AND ALLIED INDUSTRIES
(c) Cracking in the Vapour Phase. — When working
with a two-phase, liquid, and vapour system, conditions are
limited by the fact that for any particular temperature the
corresponding definite vapour pressure must be employed.
Therefore, to attain the high temperatures required, corre-
spondingly high pressures must be employed. Moreover,
temperature and pressure cannot be varied independently
of each other. With a single-phase vapour system this
objection disappears.
Several processes operating on the principle of heating
the vapours instead of the oil, have met with some measure
of commercial success. For example, Hall (J S.C.I., 1915,
p. 1045) designed a process which is in operation at present.
The oil to be cracked, a heavy kerosene or gas oil, is
first preheated and then passed through a cracking coil,
which may be heated up to 600° C. This coil is of small
diameter (i inch) and of great length (over 300 feet). The
products are pumped through at high velocity, little or no
coke being deposited in the tubes. The vapours are then
allowed to expand suddenly into a vessel of large diameter
filled with packing rings, the temperature being consequently
reduced to about 325° C. Quantities of carbon separate
out in this vessel. The vapours are then passed through a
dephlegmator where the less volatile constituents separate
out, the rest of the vapours being then passed through a
compressor working up to five or six atmospheres. The
product is then condensed in the ordinary way. By working
at higher temperatures aromatic hydrocarbons have been
produced by the Hall process, the loss by formation of non-
condensable gases being in this case, however, excessive.
Another example of a process of this type is that of
Rittman (Bulletin 114, U.S. Bureau of Mines, 1916). The
Rittman furnace consists of a battery of vertical cracking
tubes of diameter up to 10 inches and 12 feet in length.
The vapours of the gas oil to be cracked are heated in
these tubes at pressures up to 6 or 7 atmospheres, and
temperatures from 600° to 700° C. according to circum-
stances. These tubes are provided with a central cleaning
HYDROGEN ATING PROCESSES 235
rod and are connected at their lower ends to a tar pot.
An attempt was made to utilize this process for the
manufacture of benzene and toluene during the war, but
no measure of success was attained.
In other forms of plant for cracking in the vapour phase
superheated steam is introduced. For example, Greenstreet
(Eng. Pat. 16542, July, 1912) forces a mixture of oil and
steam through a cracking tube ij inches diameter and
100 feet in length, heated to a cherry-red heat, under
considerable pressure. Greenstreet claims that in this way,
mainly paraffins and defines are produced.
(d) Hydrogenation Methods. — The classic researches
of Sabatier and Senderens on the catalytic effect of nickel
in accelerating hydrogenation has given rise to the modern
industry of hardening fats. Numerous attempts have
consequently been made to apply this process to the hydro-
genation of petroleum products. Hydrogenation by means
of steam has also been tried by various inventors, so far,
however, with little measure of success.
Bergius has carried out pioneer work on hydrogenation at
high pressures. He claims that heavy mineral oils may be
transformed into low boiling products by treatment with
hydrogen at 400° C. under a pressure of 100 atmospheres.
Under these conditions no coke is formed, and the amount of
uncondensable gases is less than in the case of a cracking
process (Zeit. angew. Chem., 1921, p. 341). He claims that
even coal can be so treated to yield large percentages of oil.
The possibilities of such a process are very fascinating and
foreshadow the eventual manufacture of petroleum products
from waste vegetable matter. The technical difficulties,
however, of working at such high pressures are very great.
Day (U.S. Pat. 826089, July, 1906) claims to hydrogenate
unsaturated hydrocarbons by bringing them into contact
with hydrogen and a catalyst such as palladium or hydrogen
at high pressure. No satisfactory method of hydrogenation
of petroleum hydrocarbons, however, has so far been
developed.
(e) Various other Methods. — The well-known use of
236 PETROLEUM AND ALLIED INDUSTRIES
aluminium chloride for effecting syntheses in organic
chemical research work has suggested its application in this
case also, Friedel and Craft having themselves tried the
effect of this reagent on petroleum oils. They showed that
not only a synthetic action, but also a disruptive action,
may be effected. Egloff and Moore particularly have in-
vestigated these reactions (Met. and Chem. Eng., 1916,
p. 340). McAfee (Trans. Am. Inst. of Chem. Eng., 1915,
p. 179) has studied the possible application of the method
and has patented a process (U.S. Pat. 1235523, July,
1917) for which he claims that he obtains a substantially
complete conversion of higher-temperature boiling petroleum
oils into lower-temperature boiling oils. He operates the
process by passing chlorine into the oil, containing finely
divided aluminium in suspension. The chlorine is evolved
mostly in the form of hydrochloric acid gas which can be
recovered. A conversion of the higher boiling oils into
benzine is claimed. The oil during the process must be
kept in agitation, and moisture and sulphur compounds
must be rigorously excluded. The recovery of the aluminium
chloride would present a somewhat difficult problem.
Attempts have also been made to bring about cracking
by submitting oil vapours to silent electrical discharges.
Cherry, Robertson, and others have suggested such methods.
A very full account of the various methods which have
been proposed is given in " Gasoline and other Motor Fuels,"
by Ellis and Meigs (D. van Nostrand Co.), to which the
reader may be referred for further information on this
interesting, but, so far, incompletely worked out subject.
SECTION G.— REFINERY WASTE PRODUCTS—
THEIR REGENERATION AND UTILIZA-
TION
IN connection with various refinery processes, particularly
the chemical treating and filtration, various products
result which are too often allowed to run to waste. Even
in the case of crude oil itself much emulsion, commonly
called B.S., accumulates at the bottom of the storage tanks.
This material, which may contain large percentages of oil,
was at one time allowed to run to waste, or was burnt. It
is now usually treated, either by the electric dehydration
process, or by means of the super-centrifuge. Both these
processes have been described in Part III., Section D.
From the distillation of crude oil and more particularly
from cracking operations, quantities of gas or light vapours
are evolved. These consist partly of condensable, partly of
non-condensable gases, and in the case of gases from cracking
operations, usually contain quantities of defines.
The condensable gases are usually absorbed in modern
refineries by means of some form of gas absorber or scrubber,
the non-absorbable gases being led to a gasholder and
eventually used as fuel. In certain cases the gases from
cracking stills contain propylene, which is absorbed in
sulphuric acid. This, on subsequent treatment with steam,
liberates propyl alcohol, which is utilized in admixture with
benzine as a motor spirit. This is analogous to the prepara-
tion of alcohol from the ethylene in coal gas by means of the
Bury process (Chemical Age, August 28, 1920).
Very large quantities of sulphuric acid sludge result from
the treatment of light oils, lubricants, and paraffin wax.
Much attention has been given to the recovery or utilization
237
238 PETROLEUM AND ALLIED INDUSTRIES
of these acid sludges, in many cases, however, with little
success. The character of the acid sludge depends naturally
on the character of the oils which have been treated.
In many cases the acid sludge is merely diluted with
water. This causes a quantity of oil to separate out, which
is skimmed off or absorbed in a heavy oil and used as fuel.
The diluted acid cannot usually be reconcentrated success-
fully as it still contains organic matter in solution, so that on
concentration reactions take place resulting in the evolution
of sulphur dioxide and the separation out of carbonaceous
matter which clogs up the concentrating plant. In many
cases it pays to purchase fresh acid rather than concentrate
the waste.
In the case of acid sludges which result from the treat-
ment of lubricating oils, they may be treated with live steam,
the oils which separate out being mixed with petroleum
residues and used as fuel. If the material separating out
from the sludge is of an asphaltic nature it may be incorpor-
ated with lime and used as an asphaltic waterproof material
(Baskerville, J.S.C.L, March 15, 1920) (vide also " Sludge
asphalts," p. 228).
The diluted acid is in some cases neutralized with lime
and the precipitated calcium sulphate removed. The
solution then contains calcium snlphonates which may be
salted out by calcium chloride. These calcium sulphonates
37ield sulphonic acids from which soaps may be prepared.
As the calcium and magnesium sulphonates are soluble in
water, soaps made from these sulphonic acids will produce
good lathers with sea water (Divine, U.S. Pat. 1330624).
The sludge obtained from the treatment of lubricating
oils ma}7, after dilution and removal of the diluted acid, be
incorporated with liquid fuel or thin asphalt to make a
hot-neck grease. The diluted acid, freed from oily matters,
may be concentrated down and then allowed to flow into a
retort kept full of concentrated acid through which a current
of air is blown. The organic matter is thus destroyed and
the acid vapours given off may be condensed and concen-
trated (Ger. Pat. 221615, June 19, 1909). Much work
REFINERY WASTE PRODUCTS 239
still remains to be done before the problem of the recovery
of the waste sulphuric acid can be really satisfactorily solved.
Quantities of waste soda sludge from the treating of
petroleum distillates also result. These sludges contain,
in addition to much free soda, sodium naphthenates. These
may be obtained by concentrating down the lye and salting
out with common salt. The naphthenates (soaps) separate
out and may be freed from excess of water. These soaps
can be used as low-grade soaps, but they have an objectionable
odour. The naphthenic acids themselves may be liberated
by the addition of sulphuric acid. They may be used as
antiseptics, timber preservatives, solvents for varnish,
resins, and as substitutes for turkey red oil.
Markownikoff has shown that these naphthenic acids
belong to a group with the general formula CnH2n-2^2»
being carboxylic acids of the hydrocarbons of the naphthene
series. Several of the lower members of the series, e.g.
C6HnCOOH, sp. gr. 0-950, b. pt. 216 °C., have been isolated.
(N. Chercheffsky, " I<es Acides due Naphte." Paris, Dunod
et Pinat.)
From the filtration and treatment of lubricating oils,
kerosenes and paraffin wax by means of fuller's-earths, much
impregnated powder is obtained.
In the case of powders from the treatment of kerosene,
the material is first treated with water. This causes the
bulk of the absorbed oil to separate out. The oil is used as
fuel. The sludge powder is then dried and regenerated by
being passed through one of the ordinary type of roasting
furnaces.
The black powder obtained by the filtration of lubricating
oils is usually first treated with benzine. The benzine
solution is then concentrated down, the residue furnishing a
low-grade lubricant, the benzine being distilled off, condensed
and re-used. The resulting powder is then roasted.
The powders left after the treatment of wax are
either extracted by benzine, or steamed out, the latter being
the cheaper process. The wax-free powder may be again
regenerated by roasting.
240 PETROLEUM AND ALLIED INDUSTRIES
The lead sulphide sludge obtained as a by-product from
the treatment of oils by means of the sodium plumbite
process is usually returned to the lead smelters.
Automobile lubricating oils after use may be easily
cleaned and reconditioned by filtration and washing with
sodium carbonate solution, any dissolved benzine being
removed by evaporation. Such reconditioned oils may be
re-used with complete satisfaction (W. F. Parish, paper read
before Am. Chem. Soc., Rochester, 1921).
PAKT VIII.— THE CHARACTERS AND
APPLICATIONS OF PETROLEUM
PRODUCTS
[The characters and applications of the naturally occurring gases, solid
bitumens and pyrobitumens, and the mineral waxes have already
been dealt with, vide Parts II., V. and VI. The characters and applica-
tions of the manufactured products will be dealt with in this part.]
SECTION A.— BENZINES
THE volatile liquid products are utilized chiefly as motor
fuels and as solvents. Relatively small quantities find special
applications, e.g. the most volatile fractions may be used
as refrigerants. Wght benzines boiling completely below
100° C. are used for carburetting air to make the so-called
air gas or petrol gas, often used for lighting country houses
far removed from coal-gas works.
Quantities of special boiling-point benzines are used
for the extraction of oils from seeds. The range of boiling
point required varies according to the type of extraction
plant in use. Benzines of boiling point ranges 80° to
100° C., 90° to 110° C., and 100° to 120° C. are in common
use. Such benzines should be well fractionated and well
refined to get rid of any constituents of strong odour. A
special range of boiling point is demanded for such benzines
in order to exclude both the light volatile fractions, which
would bring about high working losses, and the higher
boiling-point constituents which would not be readily
evaporated from off the extracted oil solution (Shrader,
" Solvent Extraction in the Vegetable Oil Industry," Chem.
and Met. Eng.t vol. 25, p. 94).
Quantities of benzine, sometimes of special boiling-point
p. 241 !6
242 PETROLEUM AND ALLIED INDUSTRIES
range, are used as solvents for rubber in the manufacture of
fine rubber goods.
Very large quantities of heavy benzine, or rather light
kerosene, are used under the names of " white spirit " or
" mineral turps " in the manufacture of paints, varnishes,
and so forth. In order to comply with regulations such
white spirits are distilled to have flash-points over 73° F.
The final boiling point varies according to requirements,
grades boiling between 140° C. and 200° C., and others with
final boiling points up to 250° C., are on the market.
The bulk of the light petroleum distillates under the
names of motor spirits, petrols, benzines, naphthas, and gaso-
lines are consumed as motor fuels.
The subject of the efficiency of a motor fuel, and the
factors on which this depends, is one which has received
much attention during the last two or three years. It is a
subject of great importance, as the urgent necessity for
economy in fuel consumption is being brought to the fore
owing to the rapid increase in the output of motor vehicles,
the rate of increase of which at the present time tends to
exceed that of increase of the petrol supplies. This demand
for motor spirits has of late years increased so enormously
that at least 90 per cent, of the production of light
petroleum fractions is used for this purpose. The following
figures illustrate this : —
1
.
Year.
Total consumption in U.S. of motor
spirit in automobiles in millions of
U.S. gallons (approx.).
spirit in U.S. in millions
of U.S. gallons
(approx.).
igll
250 i
e. 31*2 per cent, of
800
1913
450
. 37'5
Jt
I2OO
1915
850
, 48-5
tl
1750
1917
1750
, 62-5
t>
2800
1919
3400
. 85
lt
4000
I92O
3900
, 82
„
4750
In consequence of this ever-increasing demand strenuous
efforts have been made to increase the production of motor
spirit in every way possible. This has been effected in the
main in three ways : (i) by increasing the yield obtained from
BENZINES
243
the crude, (a) by improvement in refinery methods, (b) by
alteration of quality ; (2) by increasing production of
gasoline extracted from natural gases ; and (3) by the pro-
duction of gasoline made by cracking processes.
The changes in" quality of the gasoline produced in the
United States is indicated by the increase in the final boiling
point, which has taken place in spite of improved methods of
refining.
Year.
Percentage distilling to 100° C.
Final boiling point °C.
1915
40
185
1917
30
2OO
1919
25
220
1920
22
230
The following table gives the production of gasoline in
the United vStates from natural and casing-head gas (Dykema,
U.S. Bureau of Mines, Bulletin 76) : —
Year.
Gasoline produced.
U.S. gallons.
Average yield per
1000 cu. ft. of gas.
No. of plants.
I9II
7,425,800
3-00
I76
1912
I2,o8l,200
2 '60
250
1913
24,060,800
2'43
341
1914
42,652,600
2'43
386
1915
65,364,7°°
2'57
414
1916
103,492,700
0-496
596
1917
217,884,100
0-508 886
In 1914 the production of gasoline by cracking amounted
to little more than i per cent, of the total output ; in 1920
this figure had increased to nearly 5 and is steadily increasing.
The characters of a motor spirit depend on both its
physical properties and chemical composition. In countries
where benzine is sold by volume, the specific gravity is
naturally a factor of some importance, as it determines the
weight of fuel per gallon or litre.
The point of prime importance to the user is the obtain-
ing of the maximum work for the money expended. The
calorific value of the motor fuel per unit volume is thus of
244 PETROLEUM AND ALLIED INDUSTRIES
great importance in countries where motor fuels are sold by
volume.
The calorific value per unit weight of the paraffins is
higher than that of the naphthenes, which is in turn higher
than that of the aromatic hydrocarbons. The specific
gravities of these three classes of hydrocarbons (in the case
of the members in most general use as motor spirits) vary
in the other direction. As a result of this the calorific value
per unit volume is largest in the case of the aromatic hydro-
carbons.
Hydrocarbon.
Sp. gr.
B.Th.U.'s
perlb.
B.Th.U.'s per
gallon.
Heptane (paraffin)
Hexahydrobenzene (naphthene)
Toluene (aromatic)
0-688
0776
0-884
19,400
18,900
17,660
133.470
140,660
153,640
If, therefore, the high specific gravity of any motor fuel
is caused by the presence of naphthenes and aromatics
and not of paraffins of high boiling point, the high specific
gravity is a decided advantage.
Specific gravity alone is utterly useless as a criterion of
quality for obvious reasons. A mixture of light benzine
and kerosene, quite unsuitable as a motor fuel, may have the
same specific gravity as a good homogeneous benzine of
reasonable boiling range. A sample of motor benzol, an
excellent fuel, may have a specific gravity higher than that
of a light paraffin gas oil. Unfortunately, owing to the fact
that the motor fuels first on the English market were of
the paraffin type, the idea that low specific gravity was a
criterion of quality became deeply rooted in the minds of
the motoring public, a mistaken idea which dies very hard.
The range of boiling point is a character of more import-
ance. The fuel must contain sufficient light fractions to
render it sufficiently volatile to enable starting up the
engine at ordinary winter temperatures without unreasonable
difficulty. The degree of ease with which any engine can
be started depends as much or more on the engine as on the
BENZINES
245
fuel, the design of the induction system having very much
influence. However, for a definite engine, the ease with
which a fuel will start up depends on two factors, (a) the
range of air mixtures over which the fuel will burn, and
(b) its volatility. As regards the burning range, all petroleum
motor spirits are similar. Only mixtures of air and benzine
vapour, containing between 2 and 5 per cent, approximately
of the latter, are explosive. Alcohol, on the contrary, has a
much larger range, viz. from 4 to 14 per cent.
The volatility of a fuel depends on its composition,
not only on the percentage of any particular volatile hydro-
carbon, but on the relative quantities of the less volatile
fractions too. In a rough way, volatility may be taken as
measured by vapour pressure, but as the conditions under
which evaporation take place in a vapour pressure apparatus
and in an internal combustion engine (the relative proportions
of vapour and liquid being so different) differ so greatly,
conclusions drawn from vapour pressure determinations
may be quite erroneous. The following table gives the
vapour pressure of various fuels at o° C. : —
Vapour pressure
Fuel. in mm. at o° C.
w-pentane . . . . . . . . 183
tt-hexane . . . . . . . . 45
w-heptane .. .. n*5
Benzene . . . . .... 26
Toluene .. ,. .. .. 9
Cyclohexane .. 27*5
Ethyl alcohol . . 12
The following table gives the boiling-point ranges of
a number of motor spirits and their vapour pressures : —
Fuel.
Sp. gr.
15° C.
Distillation test, boiling up to
Final
boiling
point.
Vapour pres-
sure at o° C.
80° C.
100° C.
120° C.j 140° C.
160° C.
I
0782
2
18
55
83
96
165
28 mm.
2
0725
12
55
82
93
98
1 60
55 ..
3
0704
27
67
86
95
—
152
70 .,
4
0760
15
66
89
97
165
19 „
246 PETROLEUM AND ALLIED INDUSTRIES
Ricardo, in a series of articles in the Automobile
Engineer, February to August, 1921, has dealt with this
subject among others. He finds that the rise of temperature
brought about in the induction pipe of a standard engine,
run under standard conditions with heat supplied to the
air induction pipe at a standard rate, gives a measure of
the volatility of a motor fuel. This figure involves latent
heat as well as vapour pressure.
The upper end of the range of boiling point is in some
respects of great importance. If the motor fuel contain
fractions of too high boiling point, then a certain amount
of condensation will take place on the cylinder walls, and
the high boiling fractions so condensed will gradually find
their way past the pistons into the crank-case, where they
will dilute the engine oil. This will sooner or later give
rise to bearing trouble. With a motor spirit of too high
final boiling point it will be found necessary to change the
lubricating oil more frequently. A final boiling point of
220° C. may be taken as permissible, although many motor
spirits on the market, particularly in the United States,
have final boiling points exceeding this. The high final boiling
point is the chief objection to benzol-kerosene mixtures as
motor fuels.
Of very much greater importance, however, is the
question of the efficient burning of the fuel in the motor, as
on the efficiency depends the fuel consumption per brake
horse-power hour, a question of the greatest importance to
the user and to the world at large. It is in this connection
that the chemical composition of the fuel plays such a very
important part.
The efficiency of an internal combustion motor, assuming
that the working fluid is a perfect gas, is given by the formula
•y-l
y being the ratio of the specific heats of a gas.
r being the compression ratio, i.e. the ratio of the volume
of the cylinder at the bottom of the stroke to that at the
BENZINES 247
top. As, however, a mixture of benzine vapour and air is
not a perfect gas, this expression must be modified. Tizard
and Pye (Automobile Engineer, February, 1921) have
/j\° '258
found that the expression E = i — ( - J gives the correct
values.
It can be seen from this formula that the efficiency
of an internal combustion engine varies with the com-
pression ratio —
Compression
ratio. Air cycle efficiency.
4:1 . . . . . . 42*56 per cent.
5:i •• ... .. 47*47 »
6:1 51-16 „
7:1 •• •• •• 53*98 „
Experiments carried out in a special variable compression
engine by Ricardo, gave the following actual figures for
indicated thermal efficiency : —
Compression Actual indicated Efficiency relative to
ratio. thermal efficiency. air cycle efficiency.
4:1 . . 277 per cent. . . 65-0 per cent.
5:1 ..31-9 „ .. 67-1
6 : i . . 35'3 N • • • 68-8 „
7^ -•• 37'5 » •• 69-6 „
The advantage of using an engine of high compression ratio
is thus obvious.
The influence of the chemical composition of the motor
fuel here comes particularly into play.
The maximum compression ratio and therefore maximum
efficiency at which a particular internal combustion engine
can be run is limited in practice by the fact that when this
reaches a certain value dependent on the particular fuel,
detonation (the knocking or pinking of the motorist) sets in,
and this, if allowed to continue, soon brings about preignition
with consequent loss of power. When detonation occurs
in practice, the throttle must be partially closed, which is
tantamount to lowering the compression ratio of the engine,
248 PETROLEUM AND ALLIED INDUSTRIES
or the spark must be retarded, either of which means loss
of efficiency.
This subject has been investigated fully by Ricardo
(loc. cit.), who examined the behaviour of various fuels and
as far as possible pure hydrocarbons in a special engine, the
compression ratio of which could be varied and set to any
particular value even during the running of the engine.
These investigations proved very decisively one point,
namely, that of the three types of hydrocarbons found in
petroleum motor fuels, the aromatic hydrocarbons showed
least tendency to detonate, the paraffins most, the
naphthenes occupying an intermediate position. The
following table gives a list of some fuels examined and the
maximum compression ratio at which they could be used
without excessive detonation in the experimental engine : —
Fuel.
Toluene
Ethyl alcohol . .
w-xylene
Benzene
Cyclohexane
Cycloheptane . .
w-Hexane
w-Heptane
Ether
Highest usable
compression.
7 '50
7-40
6*90
5 '9°
5*90
5-25
375
2*95
The next table gives the chemical composition of certain
typical fuels examined by Ricardo, together with the
maximum compression ratios at which they could be used
in that engine : —
Composition by weight.
Fuel.
Sp.gr. is°C.
Paraffin, per I Aromatics,
Naphthenes, ; compressioi
cent.
per cent.
per cent.
I
0782
26
39
35
6-0
2
0767
IO'2
4-8
85
5 '9
3
0760
38
15
47
5'35
4
0727
61
8'5
3°'5
5'25
5
0704
80-5
4 '3
15-2
5-05
6
0718
63-3
17
35'°
4-85
BENZINES
249
Ricardo has also shown that the heats of combustion
per unit volume of the air-fuel mixtures (in the correct
proportions for complete combustion) show little variation
for all volatile hydrocarbon fuels.
Fuel.
Calorific value,
B.Th.U.'s per Ib.
Relative beats of combus-
tion per unit vol. of air-
fuel mixture giving
complete combustion.
Hexane
Heptane
Benzene - •
Toluene
Cyclohexane
Kerosene
19,390
19,420
17,460
17,660
18,940
19,100
46-0
46-06
46-9
46-9
46-08
46-14
The practical result of this is that in an engine of such
low-compression ratio (and therefore low efficiency) that any
hydrocarbon fuel could be used therein without detonation,
the relative efficiencies of all such fuels would be about the
same.
This is borne out by the following results : —
Fuel.
Sp.gr. 15° C.
Minimum consumption per I.H.P.
hour.
Lbs.
Pints.
I
0782
0-432
0-442
2
0767
0-425
°'443
3
0-760
0*422
°'445
4
0-727
0-421
0-463
5
0-704
0-414
0-471
6
0-718
0-415
0-462
If, however, the minimum consumptions per I.H.P. hour
are compared at the maximum compression ratios at which
the fuels can be used, then the effect of the increase of
efficiency so obtained is most marked.
Fuel.
Sp. gr. 15° C.
Highest usable
compression.
Minimum compression per I.H.P.
hour.
Lbs.
Pints.
I
2
3
4
6
0782
0767
0-760
0727
0-704
0718
6-0
5 '9
5 '35
5*25
5'°5
4-85
G'393
0-389
0-407
0-410
0-412
0-422
0-402
0-405
0-428
0-451
0-469
0-471
250 PETROLEUM AND ALLIED INDUSTRIES
The practical value of these Jesuits lies in the fact that a
motor spirit, rich in paraffins and poor in aromatics and
naphthenes, will detonate in the average engine when the
spark is fully advanced and the throttle open. It is, there-
fore, advantageous even in engines of low-compression
ratio to use motor spirits rich in aromatics and naphthenes
if obtainable. In the case of aeroplane engines, where
efficiency is of such great importance, which are usually
therefore of high-compression ratio, only motor fuels of low
paraffin content can be used.
The motor spirits marketed in different localities show
much variation in quality, this being largely due in the
first place to the character of the crude oils from which they
are manufactured. The specific gravity may vary much,
according to chemical composition and boiling-point range.
Spirits composed mainly of volatile paraffin hydrocarbons
may have specific gravity as low as 0*680. Spirits relatively
rich in aromatic and naphthene hydrocarbons may have
specific gravity 0*760 or more (pure benzene sp. gr. 0*884).
The initial boiling point (the determination being carried
out in an Engler flask of standard dimensions, under standard
conditions) may be as low as 30° C. or as high as 60° C. The
percentage boiling below 100° C. usually varies between
10 and 70 per cent. The final boiling point lies usually
between 160° C. and 200° C., but is occasionally as low as
130° C. and often as high as 230° or 240° C. As the method
of testing of motor spirits is so well described in various
works, this subject will not be dealt with here, but a
few words on the interpretation of the results will not
be out of place. The specific gravity must be interpreted
in connection with the boiling-point range and chemical
composition. A high specific gravity with components of
normal boiling-point range would indicate presence of
naphthenes and aromatics. The boiling point or distillation
test would show up the presence of excessive quantities
of the very volatile casing-head gasolines or the presence
of constituents of too high boiling point.
Tests are usually carried out to show that the spirit has
BENZINES 251
been adequately refined and is free from appreciable con-
tamination with organic sulphur compounds which impart
to it an objectionable odour. As the majority of the tests
are of an empirical nature, there is great diversity of method,
but steps are being taken to unify and standardize methods.
GENERAL REFERENCES TO PART VIII., SECTION A.
Dean, " Motor Fuels," Jour. Franklin Inst., 1920, p. 269.
Ellis and Meigs, " Gasoline and other Motor Fuels." D. Van Nostrand
Co., New York.
Formanek, " Benzine and Mineral Lubricants." Scott, Greenwood
and Son.
Pogue, " Economics of Petroleum," chapter ix. J. Wiley and Sons,
New York.
SECTION B.— KEROSENES, ILLUMINATING
OILS, ETC.
THE distillates which come off after the benzine fractions
and before the gas-oil fractions, are worked up into kerosenes.
There is no hard-and-fast line of demarcation between
benzine on the one hand and gas oil on the other. At
one time, when benzine was practically a by-product of no
value, as much as possible of the low boiling constituents
was included in the kerosene, with the result that this
product had almost invariably a low flash-point as near the
legal limit (73° or 76° F.) as might be. Nowadays, however,
as improved motor engines can deal with less volatile
benzines the tendency is to include part of the lower boiling
constituents of what was formerly made into kerosene, in
the benzine fraction. The removal of these lighter fractions
from the kerosene, has brought about the necessity for the
removal of a balancing quantity of heavier fractions of higher
boiling point (which now go into gas oil). Kerosenes now-
adays have thus a higher flash-point and a narrower boiling-
point range than was formerly the case, so that an improve-
ment in the quality of the kerosene generally marketed has
thus been effected.
Kerosene was at one time the mainstay of the petroleum
industry. As a cheap illuminant it has been aptly termed
" one of the greatest of all modern agents of civiliza-
tion." The recent great developments in automobile
engineering and the increased use of liquid fuels, and to a
less extent asphalts, have forced kerosene to take a back
seat.
252
KEROSENES, ILLUMINATING OILS, ETC. 253
This is well illustrated by the following table :—
Kerosene production
expressed as percentage
Year. of crude oil treated.
1899 58
1904 48
1909 .. -.33
1914 .. .. 24
1916 14
1918 .... .. 13-3
1920 I2'7
(Pogue, " Economics of Petroleum ").
The above figures refer to the United States only, but
may be taken as indicating the position generally. In
1899 kerosene represented 60 per cent, of the value of the
total petroleum products ; in 1920 only 14 per cent.
Kerosenes show great variation in quality according
to (a) the nature of the crude oil, (b) the method of distilla-
tion, and (c) the method of refining.
The quality of the kerosene from the point of view of
an illuminant can only be spoken of relatively to the type
of lamp used. With the ordinary type of lamp, kerosenes
composed largely of paraffin hydrocarbons (other things
being equal) give the highest candle power ; those composed
mainly of naphthenes do not burn so well and those rich in
aromatics will burn only with a smoky flame. With certain
suitable lamps, however, kerosenes rich in aromatics will
give higher candle power than those rich in paraffins. For
vaporizing lamps, on the other hand, all types behave well.
The method of distillation, or rather the cutting of the
distillates, may be effected so as to produce various grades.
For example, in the United States, it is usual to manufacture
two grades, one by taking a cut from the middle fractions of
the distillate, and one by mixing the lighter and the heavier
cuts together. The former naturally gives a finer and
more homogeneous product, although the specific gravity
of the latter may be the same.
The method of refining is important, as products of fine
254 PETROLEUM AND ALLIED INDUSTRIES
colour (the so-called water white) are in demand. For
kerosenes used for signal lamps and so forth, which demand
efficient burning over long periods, carefully refined products
are necessary ; for native lamps of simple construction, on
the other hand, poorly refined grades serve quite well.
The majority of kerosenes now in the market have specific
gravities varying from 0780 to 0-825 or more. Flash-points
are nowadays about 40° C. (Abel Pensky test), but may be as
high as 65° C. The low limit for flash-point for various
countries varies much, ranging from 24° C. to 45° C. or more.
The boiling-point range usually extends from 150° C. to
300° C., as determined by standard Engler flask. The
colour varies from a distinctly yellow tint to nearly
colourless.
The following table gives analyses of a few types of
kerosenes marketed, from which the considerable variation
in properties may be noticed : —
Percentage boiling in Engler flask (vol.) up to °C.
Kerosene.
Sp. gr.
15° C.
Flash-
point °C.
j |
175
200
250
275
300
A
0783
39
23
65
97
100
B
0-804
43
7
34
75
90
96
C
0-807
53
15
66
85
92
D
0-814
48
—
16
67
85
89
E
0-815
69
—
3
60
85
96
F
0-818
31
3°
55
85
93
98
G
0-820
36
15
32
68
82
91
H
0-828
36
18
52
93
98
Kerosene.
lamp to 90 per cent, consumed.
hour in grams.
A
36
1-86
B
30
i'95
C
16
3-87
D
20
3-64
E
27
2 '2O
F
18
3 '3
H
21
3 '9
KEROSENES, ILLUMINATING OILS, ETC. 255
The qualities of a kerosene must be considered in relation
to the purpose for which it is to be used. Kerosenes are
used chiefly for illuminating purposes in wick-fed lamps,
but are also largely used as motor fuels for types of internal
combustion engines fitted with vaporizing devices, and for
semi-diesel motors, and to a much less extent for other
purposes of minor importance such as insecticides and
flotation oils.
For illuminating purposes the kerosene should have
a normal range of boiling points. The final boiling point
should not much exceed 300° C., as the higher boiling-point
constituents are lacking in capillary power and do not flow
well up the wick, especially as the level of the kerosene
in the container falls. Constituents of too high boiling point
also tend to bring about charring of the wick. The kerosene
should contain no foreign matter, should be composed
entirety of hydrocarbons, should contain no acids or products
of careless refining, and should be quite free from ash.
The colour is usually considered a point of some importance,
but this is largely a matter of taste.
From the point of view of a fuel for internal combustion
motors, kerosenes have lower calorific powers per unit
weight than benzines derived from the same crude oil.
If purchased by the unit of volume, however, the advantage
lies with the kerosene, owing to the preponderating effect
of the specific gravity.
Sp. gr.
B.Th.U.'s per Ib.
B.Th.U.'s per gallon.
Kerosene
A motor spirit
o'Sio
0705
18,900
I9,I30
153,000
134,900
It would appear, therefore, that kerosene is the more
efficient motor fuel when purchased by the unit of volume.
It must be remembered, however, that the detonation
point of kerosenes is much lower than that of benzines
generally, as a consequence of which they can be used only
in engines of low-compression ratio, i.e. of low efficiency.
256 PETROLEUM AND ALLIED INDUSTRIES
Moreover, the absorption of the kerosene by the lubricating
oil is of much greater consequence than in the case of benzines.
However, owing to its low price, compared to that of benzine,
it is economical in practice, being much used as a motor fuel
for vaporizing engines used in propelling small boats and
for small land power plants.
Emulsions of kerosenes are much used as insecticides for
spraying fruit trees. The kerosene may be emulsified by
dissolving a soap in warm water and adding to it kerosene
in small amounts with vigorous stirring. Whale-oil soap is
a good material for the purpose. Pure kerosene delivered
by an efficient atomizing jet may however be used.
SECTION C.— GAS OILS
THE so-called gas oils are distillates from petroleum or
shale oils intermediate in character between kerosene and
light lubricating oils. They may be made from any type of
crude, either as direct distillates or as by-products from
some subsidiary operation. For example, as a residue
from the redistillation of a heavy kerosene distillate, as a
filter oil from the filtration of cooled wax distillates, as a
distillate from the concentration down of lubricating oil
distillate, and as a distillate from the destructive distillation
of an oil down to coke.
Gas oils form a loosely defined class of products, as is
to be expected from the fact that their main use is as fuels
for certain types of internal combustion motors, for thinning
down viscous residual oils, as a basic material for most
cracking processes, for gas enriching and for many purposes
of minor importance, such as insecticides and so forth.
As fuel oils the flash-point must lie above the usual legal
limits, 65° C. or 80° C. as the case may be. The viscosity
of gas oils is always so low as to give no trouble in this respect.
Their calorific value will depend somewhat on the nature of
the crude from which they have been manufactured, as the
hydrogen/carbon ratio is not constant. The variation is,
however, comparatively slight. The average net calorific
value of a gas oil may be taken as 9800 to 10,200 calories.
The specific gravity of gas oils may vary from 0-850 to 0*920,
the percentage boiling below 300° C. may vary very consider-
ably from a few percentages to 70 or more. Gas oils being
distillates should contain no asphaltic matter insoluble in
petroleum ether of sp. gr. 0*645, and should leave only a
very small percentage of coke (say 0*5 per cent.) on being
p. 257 17
258 PETROLEUM AND ALLIED INDUSTRIES
distilled to dryness in a crucible. (This test should be
carried out under definite conditions as laid down by
Conradson.)
Gas oils are rarely used as fuels for direct combustion
under boilers or in furnaces, as thicker residual fuels serve
this purpose equally well and are cheaper. They are,
however, largely used in internal combustion motors of the
semi-diesel type in land installations, and in diesel engines
of the marine type. Diesel engines will burn residual fuels
with success, but as more frequent cleaning of the valves
is then necessary, gas oils find more favour for marine use
where long periods of running without enforced shut-downs
are necessary.
The following table gives a few representative analyses
of various gas oils : —
Per cent.
boiling up
Flash-point.
to
°c.
Gross calorific
Sp. gr. 15 C.
P M °C
250°
300°
per gram.
A
0-848
85
6
52
10,980
B
0-860
66
18
56
10,900
C
0-863
73
13
57
II,OOO
D
0-865
75
12
48
10,600
E
0-895
65
15
46
~
Oils derived from the distillation of coal tars may also
be used for diesel engines, but as their ignition temperatures
are lower engines when running on such oils are usually
fitted with a pilot ignition jet, by means of which a little
petroleum oil is injected into the cylinder immediately before
the main charge of tar oil in order to act as a primer. The
calorific value of such tar oils is about 20 per cent, lower than
that of petroleum gas oils owing to the presence of oxygenated
bodies such as the higher homologues of phenol.
Tar oil for diesel engine use should comply with the
following specification : —
i. Must not contain more than 2 per cent, of solid
constituents insoluble in xylene.
GAS OILS
259
2. Ash must not exceed cro8 per cent.
3. Water not to exceed 2*5 per cent.
4. Coking value not to exceed 3 per cent.
5. The oil must be a distilled product.
A few typical analyses of tar oils are given herewith
(Moore, " liquid Fuels for Internal Combustion Engines ").
Oil.
Sp. gr. 20° C.
Gross calorific
value. Calo-
Flash-point
closed.
Sulphur per
Tar acids.
ries per gram. 1 Gray.
Horizontal retort
tar oil
1-049
9191
93° C.
0-65
14
Vertical retort
tar oil
1-016
9189
88° C.
0-49
28
Blast furnace tar
oil
0-903
9992
70° C.
0-28
23
The tar oils usually employed for diesel engine work
are the creosote and anthracene oils. The naphthalene and
anthracene may be removed, but there is no necessity for
tin's procedure as it is an easy matter to keep the oil liquid
by warming the feed tank.
Gas oils are also extensively used for the making of gas
for the enriching of water gas, which is now so largely used
to supplement coal-gas supplies. The plant used for this
purpose consists of four parts, viz. the generator, carburettor,
superheater, and scrubber. The operation of such plants is
always intermittent. During the " blowing period " air is
blown through the coke in the generator A (Fig. 41),
so as to allow partial combustion; secondary air is
also admitted into the carburettor B, which is filled with
checker brickwork, the combustion of the gases being
here completed. The heated gases then pass into the
superheater C, where the temperature may be controlled
if desired by admission of extra air. The products of
combustion then pass into the stack by the valve D. When
the generator and carburettor are both thoroughly well
heated and the temperature of the superheater brought
up to about from 650° to 700° C., the air supply is shut off,
260 PETROLEUM AND ALLIED INDUSTRIES
steam is blown into the generator and the valve D closed so
as to direct the gases through the scrubbers to the gas-
holders. The " blue " gas, a mixture of carbon monoxide
and hydrogen thus formed on passing through the carburettor,
comes into contact with a spray of gas oil, which is there
vaporized. On passing through the superheater, the oil
vapours are cracked into permanent gases, a certain amount
of tar being also formed. As the temperature falls owing to
the reaction between steam and carbon being endothermic,
at a certain point it is necessary to stop the process and
LOWE
FIG. 41.
revert to blowing again in order to restore the temperatures
of the generator, carburettor, and superheater. As a general
rule the blowing period occupies from three to five minutes,
the gas-making period from two to four.
Gas oil is also used for the manufacture of illuminating gas
which is used alone, e.g. for lighting railway carriages. For
the making of gas for such purposes, the gas oil is allowed
to drop slowly into retorts made of cast iron kept at a
moderately red heat.
In practice it has been found that for gas-making purposes
gas oils derived from paraffin base petroleums are best, as
GAS OILS 261
they give the maximum yield of gas. Those containing
unsaturated straight chain hydrocarbons are less efficient,
and those containing aromatics in quantity very much
less so.
GENERAL REFERENCES TO PART VIIL, SECTION C.
Diesel Engine Users Association reports.
Moore, " Liquid Fuels for Internal Combustion Engines." Crosby,
Lockvvood and Son.
Schenker, " Combustibles pour Moteurs Diesel." Dunod, Paris.
SECTION D.— FUEL OILS
L oils derived from petroleum and shale oils show great
variation in character according to the nature of the crude
from which they are derived, and the method of manufac-
ture. If oils derived from coal and low-temperature tars
be included, the variation in character is even greater.
Fuel oils may be divided broadly into two main classes,
viz. distilled and residual oils.
The distilled oils include the gas or solar oils, which
from a fuel point of view are generally similar in character
from whatever type of crude they be manufactured. These
distilled fuel oils have been dealt with in the last section.
Residual Fuel Oils are produced in the main from
asphaltic or naphthenic base crudes, being in many cases
merely the residues left after the benzine and kerosene
fractions have been " topped " or " skimmed "off. Many
such crudes yield 80 per cent, or more of fuel oils, whereas
the wax or paraffin base crudes, which are usually more
completely worked up, yield, as a rule, only from 10 to 40
per cent.
There are no hard-and-fast or even generally accepted
specifications to which fuel oils must conform, as in the
case of the lighter constituents of petroleum. Regulations
generally demand a minimum flash-point of 65° or 80° C.,
but are not exacting in other respects.
The properties to be looked for in a liquid fuel depend to
a great extent on the purposes for which and the conditions
under which it is to be used. Residual fuel oils may be
used in many cases as diesel oils, particularly for land
installations where the plants run intermittently, oppor-
tunities for frequent cleaning being thus afforded. Even
262
FUEL OILS 263
the most viscous asphaltic fuels may be used with satisfac-
tion in diesel engines, indeed coal tars may so be used,
but the preference is given naturally to distilled oils of the
gas-oil type. Many diesel oil users specify a maximum
coking value of about 4 per cent., a figure which excludes
many residual oils, the coking values of which may be as
high as 10 per cent, or more. Tars, moreover, usually
contain varying percentages of free carbon according to
the method of manufacture, from about 3 per cent, for low-
temperature up to 20 per cent, for high-temperature tars.
A coal tar suitable for land diesel engine use might have a
specification, sp. gr. below ri2 ; ash, below 0*08 per cent. ;
water less than 2 per cent. ; free carbon, not above 6 per
cent. ; coke value, not above 10 per cent. ; calorific value,
at least 9100 calories (J.S.C.I., September 15, 1919).
Liquid fuels for furnace use may, however, be allowed
much greater latitude in properties. A practical difficulty
arises from the high asphaltic (and/or wax) content of many
fuels bringing about a high viscosity and congealing point.
If arrangements can be made for heating the oil then pumping
difficulties disappear. Perfect combustion can in all cases,
however, be attained if the temperature of the fuel oil fed to
the burners is sufficiently high. Specifications for liquid fuels
are often laid down by large consumers and government
departments, limiting the viscosity, sulphur content, and so
forth.
The British Admiralty, for example, demand a viscosity
not exceeding IOQO seconds Redwood II. at o° C., a flash-point
of 80° C. and a sulphur content not exceeding 3 per cent.
The United States navy limit the specific gravity to the
range 0-85 to 0*96, the sulphur content to not exceeding
i '5 per cent., and the viscosity to not exceeding 140 seconds
Saybolt Furol at 70° F. (2i'i° C.). They also demand a
calorific value of not less than 10,000 calories per gram, taking
10,250 as the standard and paying a bonus or deducting a
penalty as the fuel oil supplied has a calorific value above or
below this value. France demands a minimum flash-point
of 93° C. and Italy 100° C. for fuel for naval use.
264 PETROLEUM AND ALLIED INDUSTRIES
The characters of a few residual fuel oils taken at random
given herewith, will illustrate the great diversity of character
of these oils.
Fuel oil.
Sp. gr.
@ 15° C.
Vise. R. 1.
@ 100° F.
Flash-
point °C.
Sulphur
per cent.
Gross calorific
value. Calories
per gram.
Texas
0-889
74
I05
0-6
IO,8oo
Persia
0-899
150
88
I '5
10,550
Borneo
0-913
4i
80
o-i
10,500
Texas
0-917
204
99
—
10,700
Trinidad
0-947
450
86
—
—
Mexican
0*955
1360
71
2-9
10,450
Mexican
0-961
2500
75
3'7
IO.2IO
Venezuela
0-963
5000
83
2-4
IO,2OO
Texas
Q'973
4850
86
0-9
10,400
A very complete list of fuels and their properties is given
in the Mechanical World for April 2, 1920, to which the
reader is referred.
The various tars derived from the distillation of coals
under various conditions and of lignite, peat, wood, etc.,
may also be used as liquid fuels. For diesel engine use
they cannot compare with the petroleum fuels. The diffi-
culty of ignition may be overcome by the use of a pilot jet
as described under tar oils (p. 258), but the presence of free
carbon in such tars is a severe handicap, as this gives rise
to much trouble with the exhaust valves. The removal of
the free carbon from such tars is difficult and hardty an
economic proposition. The relatively high ash content also
militates against their successful use.
When tars are used in furnace work the objections
mentioned above naturally largely disappear. The
high specific gravity of the tars makes the separation
of water difficult, and the low calorific value must always
remain an objection, which, however, may be nullified
by price of the tars in relation to fuels of higher calorific
value.
Analyses of several types of tars are herewith given
(Moore, " liquid Fuels for Internal Combustion Engines ").
FUEL OILS
265
Tar.
Sp. gr.
@I5°C.
Elementary Analysis.
Ash.
Coke.
Net calorific
value. Calories
per gram.
Free
carbon
per
cent.
C.
H.
S.
Horizontal
1
I
retort . .
I'lSo
91-5
5'2
0'5
O'2O
24-0
8645
18-2
Vertical re-
tort
1-089
88-0
6-8
0-6
0-03
6-1
8664
17
Simon-Carve
coke oven
I'OQO
88-1
5'6
0-2
0-07
6-0
9261
traces
Low temper-
ature car-
bonization
1-058
85-8
8-1
0-09
O'll
8-2
8776
2-2
Water gas..
i'°54
92*2
6-8
0-6
trace
187
8647
6-8
Blast
furnace . .
1-172
89-5
575
0-84
0-36
23H
8288
9'5
Methods of Burning Liquid Fuels. — liquid fuels are
usually burnt under furnaces by one of three methods, the
choice of method depending upon conditions, viz. (a) injection
or atomizing by means of steam, (b) by means of compressed
air, (c) by means of pressure only. Atomizing jets may be
divided into three main groups : (i) those in which the
atomizing is effected by the simple impact of a stream of
oil and air or gas, (2) those of the injector type, and (3) those
of the direct spray type, in which no spraying agent is
emplo3^ed, the oil being merely forced under pressure through
a suitable jet. Innumerable forms of burner have been
devised (Report of the United States Liquid Fuel Board,
1904), the description of which lies beyond the scope of this
work. The steam injection system is very simple and is
much used for land installations. An objection to this
system is the fact that about 6 per cent, of the steam raised
is used for spraying the liquid fuel For this reason this
arrangement is rarely if ever installed in sea-going vessels.
The compressed air system is not much used as the installa-
tion of auxiliary compressor plant is necessary. For small
installations or where compressed air is available this method
of injection is useful, as it is very easy to manipulate. The
pressure jet system is the most economical in practice, the
steam required for pumping and heating the oil amounting
266 PETROLEUM AND ALLIED INDUSTRIES
to only about 2 per cent, of that generated. The system
may be applied to even the thickest and heaviest oils provided
that the oil is heated to a sufficiently high temperature before
injection. If this temperature be too low incomplete
combustion with production of much smoke results.
The advantages presented by burning liquid fuels in
place of coal are very great. The calories per unit weight
are considerably greater in the ratio of approximately i "6 to
i, so that with certain prices the actual number of calories
per unit cost may be greater. If, however, this is not the
case, there are so many collateral advantages on the side of
oil that the higher cost per calorie is usually more than
completely counterbalanced. Among such advantages may
be enumerated the following : Less room required for
storage ; less difficulty and cost in transport and handling ;
more uniformity in fuel ; absence of ash, cleaning of furnaces
and costs of removal of ashes thus being avoided ; less wear
and tear on the plant ; greater efficiency of the boilers,
resulting in lower maintenance costs, and lower capital
outlay for a definite steam-raising capacity, or increase in
capacity for an existing plant ; greater flexibility and easier
control in running, and very much reduced labour charges,
not to mention such minor advantages as absence of smoke
and general cleanliness.
When applied to marine use further advantages result
in : the superior evaporative power per unit weight of
fuel carried, thus ensuring greater radius of action, or less
weight of fuel necessary for a given voyage, thus allowing
more cargo space, and ease of bunkering and consequent
saving of valuable time.
Nevertheless, to quote Beeby Thompson, " From an
economic point of view, the burning of oil under boilers can
only be regarded as a wanton waste of the world's resources,
as each pound of oil consumed under boilers is capable of
yielding four or five times the power if applied in accordance
with modern methods," i.e. in internal combustion engines.
As liquid fuel presents such numerous advantages over
coal, particularly for sea-going vessels, the world's shipping
FUEL OILS 267
is rapidly turning to the use of oil, indeed the world's navies
have already adopted it as their standard. Whereas 10*5 per
cent, of the world's shipping tonnage in 1918-19 used oil fuel
under boilers, 16-3 per cent, used it in 1919-20 (The Naval
Annual, 1920-21, lyondon, p. 180). During the last few
years bunkering stations in great number have been con-
structed by the leading oil companies, so that now ample
supplies are ensured at numerous points on the great trade
routes throughout the world.
GENERAL REFERENCES TO PART VIII., SECTION D.
Baillie, " Fuel Oil Burning," J.R.S.A., vol. 69, 1921, p. 231.
Brame, " Liquid Fuel and its Combustion," J.I.P.T., 1917, p. 194.
Brewer, " Efficient Handling of Fuel Oil," Power, 1921, January-March.
Dunn, " Industrial Uses of Fuel Oil." Technical Publishing Co., San
Francisco.
Moore, " Liquid Fuels for Internal Combustion Engines." Crosby,
Lockwood and Son.
North, " Oil Fuel." C. Griffin and Co.
Sothern, " Oil Fuel Burning in Marine Practice." Munro and Co.,
Glasgow.
SECTION E.— PARAFFIN WAX
ALTHOUGH paraffin wax cannot be regarded as one of the
main products of petroleum it is, nevertheless, produced in
large quantities, not only in the United States, where
production for 1920 amounted to 152,000 tons, but also in
the East Indies, Burmah, Rumania, Galicia, Mexico, and
elsewhere. It is, moreover, produced in quantities from
shale oil, as in Scotland, and from the distillation of lignite
in Thuringia.
Paraffin wax, together with ceresin and montan wax,
finds its chief use for the manufacture of many articles for
which otherwise the more expensive bees- or other wax
would be used. In many cases, too, new industries involving
the use of paraffin wax, have been developed. A good
example of the replacement of beeswax by paraffin is
afforded by the " batik " industry in Java. Fabrics are
dyed by the natives by first covering the portions of the
surface which are not to be dyed by a layer of batik wax,
applied in the melted state by hand, by means of a very
small kettle, and then immersing the material in the dye.
After dyeing, the wax is removed by hot water and used
again. Beeswax was at one time almost universally used
for this industry, but it has been largely replaced by substi-
tutes composed in the main of paraffin wax, blended with
such substances as carnauba wax, montan wax, japan
wax, resins and the like. Many such varieties of vegetable
or animal wax substitutes are made. Paraffin wax also
enters largely into the composition of polishes for floors,
leather, etc. Large quantities are used in the electrical
industries for insulating purposes, often directly, often in
admixture with resin, tallow, etc., for cable work. The use
268
PARAFFIN WAX 269
of paraffin wax for waterproofing paper for packing purposes,
for making jam pots and the like, is now the basis of a
considerable industry. It is so used in the making of
washable wall-papers, for waterproofing cartridges, in the
waterproofing of chrome leather. It also plays an important
part in the waterproofing and finishing of textile fabrics.
For making rainproof material, a solution of paraffin wax
in benzine or other volatile solvent is sprayed on to the
cloth. In conjunction with ceresin and soap, together with
starch and filling material, it is used for glazing certain
fabrics by hot calendaring. It is also used in laundry work
for imparting a high gloss to collars, etc.
It is also used as a convenient base for many ointments
for medical use in admixture with wool fats and oils, and in
quite another direction for surgical use as a dressing to
exclude air and even in place of plaster of Paris for splints.
For many other minor purposes such as manufacture of
crayons, sealing waxes, etc., quantities are used.
By far the largest quantities, however, are used for the
manufacture of candles, nightlights and the like. Candles
are made by casting in moulds made of an alloy of tin and
lead, the wick being placed in situ before running in the
wax. These moulds are grouped together in machines
which may contain 200 or more moulds. Candles may be
made of pure paraffin, but it is usual to employ mixtures,
because pure paraffin has a tendency to stick to the moulds,
and, moreover, candles of pure paraffin soften too readily
on exposure to only moderate temperatures. Stearine, a
mixture of stearic and palmitic acids prepared by the
splitting of certain fats, is mostly used for this purpose,
grades of melting point 55° C. being usually selected.
Mixtures of stearine and paraffin have always melting points
lower than those of the constituents, but in spite of this
they stand up better to heat and less readily become plastic.
The real advantage of adding stearine is this stiffening
effect. The white marble-like appearance caused by the
addition of stearine is of minor importance ; nevertheless,
attempts have been made to imitate this by the addition
270 PETROLEUM AND ALLIED INDUSTRIES
of small percentages of such substances as /3-naphthol.
Candles may be coloured by the use of certain aniline dyes
which are slightly soluble in paraffin wax or stearin,
e.g. methyl violet, malachite green, quinoline yellow, and
so forth. Although the quantities used are so minute,
colourless candles always burn better.
The wick plays a very important part, and great care
must be bestowed on its manufacture. A wick must be
" self -snuffing," i.e. it must bend over so as to project into
the outer oxidizing atmosphere of the flame, and must be
impregnated with certain chemicals to enable it to burn to
a light powdery non-coherent ash. The former is attained
by weaving the wick with one set of strands under greater
tension than the others, the latter by impregnating the
wick with such salts as potassium chlorate, ammonium
nitrate, ammonium phosphate. In addition to being used
for the direct manufacture of wax matches, paraffin of low
melting point, about 47° C. is used for impregnating the tips
of wooden matches.
GENERAL REFERENCES TO PART VIII., SECTION E.
Campbell, " Petroleum Refining." C. Griffin and Co.
Graefe, " Die Braunkohlenteer-Industrie." W. Knapp, Halle.
Gregorius, " Mineral Waxes." Scott, Greenwood and Son.
Lamborn, " Modern Soaps, Candles, and Glycerin." Crosby, Lock-
wood and Son.
Scheithauer, " Shale Oils, and Tars." Scott, Greenwood and Son.
SECTION F.— LUBRICATING OILS
THE subject of lubrication generally, and more particularly
that of the relation between the chemical and physical
properties of an oil and its practical lubricating value, is
one of great difficulty. Much has been written on the subject,
but there is a great lack of concrete fundamental data, so
that the basic problems are still far from being solved.
Up till quite recent times, lubrication presented no
difficult problems. Vegetable oils and fats were used, sperm
oils for light-running machinery, rape, castor, and lard oils
for heavier work, and tallow for the heaviest. As modern
high-speed machinery developed and as the demand for
lubricating oil increased, mineral lubricating oils began to
come into use, naturally first by blending with sperm and
other fatty oils. Thus according to Parish (Chemical Age,
New York, 1922, p. 61), the lubricating oil business developed
along most complicated lines, so that " in a decade the lubri-
cating practice of the world was one jumbled mass of dis-
associated facts due to the practice of producing a compara-
tively few number of oils at the refinery and of compounding,
mixing, and branding an immense and complicated number
of oils, many of them finally being used for the lubrication
of the same class of machinery, as, for instance, high-speed
machinery working under about the same mechanical
conditions, but being lubricated with a great number of
different kinds of compounds and mixtures sold under a
multitude of names, all descriptive of the machine on which
the oil was intended to be used." In this manner the
lubricating- oil trade developed, and in this manner it exists
to-day. There is, however, a tendency to improvement.
271
272 PETROLEUM AND ALLIED INDUSTRIES
The futility of present methods is being recognized, the
number of brands is being reduced and efforts are being made
to study the problems and acquire data of real value. With
the modern developments of machinery new lubricating
problems have arisen, such as the lubrication of superheated
steam cylinders, and internal combustion engines of various
classes. Such special conditions call for certain types of
oil regarding which a good deal of empirical knowledge
has been accumulated. In all cases of lubrication the
design and condition of the surfaces to be lubricated play
much the most important part. Bearings of the Michell
type are so nearly perfect that the character of the oil used
is of quite secondary importance.
The physical property most generally considered in
relation to lubricating value is the viscosity. In the case of
lightly loaded spindles running at high speed the viscosity or
internal friction of the oil is the factor of prime importance,
so in dealing with such cases there is little difficulty. In the
case of heavily loaded bearings, however, the problem is
one of the capability of the oil of forming a thin film and of
maintaining this film without breaking down under conditions
of great stress.
According to Ivangmuir the spreading of the oil in a film
only one molecule thick depends on a definite chemical
attraction between the metal and the oil. According to
this view unsaturated compounds should be better lubricants
than saturated. This is, in fact, borne out by the work of
Wells and Southcombe on the effect of the addition of small
percentages of fatty acids to mineral lubricating oils (J. S.C.I.,
vol. 39, p. 5iT). This has led to efforts to correlate the lubri-
cating power of an oil with its surface tension relative to
metals, a difficult problem which has not yet been successfully
attacked. Holde (Chem. Ztg., 1921, p. 3) states that mineral
lubricating oils have on the average lower surface tensions
than fatty oils. He takes the product of the surface tension
of an oil in air with the cosine of the angle of contact as a
measure of the affinity of an oil for the metal to be lubricated.
He also confirms Wells' and Southcombe's observations,
LUBRICATING OILS
273
Oils derived from petroleum have largely replaced the
vegetable and animal oils once generally used. Mineral
oil lubricants can be manufactured in great variety, ranging
from the thinnest spindle oils more limpid than sperm oil
to the thickest oils more viscous than castor. The viscosities
of mineral oils fall off more rapidly with increase of tempera-
ture than do those of fatty oils, this phenomenon being much
less marked, however, at temperatures over 40° C. (Archbutt
and Deely, "Lubrication and Lubricants," p. 191). The
more viscous the oil, the more marked is the change of
viscosity with temperature. Woog (Comptes rendus, 1921,
P- 3°3) found (cryoscopically) that the mean molecular
volume of a fatty oil was much less than that of a mineral
oil of the same viscosity.
Of the chemistry of mineral lubricating oils little is
known. They consist of hydrocarbons of high molecular
weight, consequently the difficulty of isolating any group
of individuals and still more so of elucidating their constitu-
tion is very great. Marcusson (Chem. Ztg., 1911, pp. 729, 742)
holds that the constituents to which mineral oils chiefly
owe their lubricating power are those which do not react
with formaldehyde and sulphuric acid. Mabery (" Composi-
tion of Petroleum and its Relation to Industrial Use,"
Am. Inst. of Min. and Met. Engineers, February, 1920)
states that hydrocarbons of the general formula CnH2n_4 form
the constituents of the best lubricants it is possible to prepare
from petroleum, and that heavy petroleums of an asphaltic
base contain these hydrocarbons in large proportion, and
lighter varieties in small amounts. He also concluded that
hydrocarbons of the series CnH2n+2 had a low lubricating
value, and that the lubricating hydrocarbons from Pennsyl-
vania petroleums consisted mostly of the series C2H2n and
CnH2n_2. Aisinmann (J. S.C.I., 1895, p. 2812) states that the
lubricating oils of Baku are composed mainly of naphthenes
and defines, but this has been disputed.
Unsaturated hydrocarbons constitute 20 to 40 per cent,
of most lubricating oil distillates. They can be and often
are removed by treatment with concentrated sulphuric
p. 18
274 PETROLEUM AND ALLIED INDUSTRIES
acid, as in the ordinary process of refining. Certain unsatu-
rated hydrocarbons and asphaltic resins, which are probably
mainly responsible for gumming and carbonization of oils,
should be removed, but it is open to question as to whether
the sulphuric acid treatment does not also remove desirable
unsaturated constituents.
The saturated constituents are probably naphthenic and
polynuclear in structure, but it is possible that isoparaffins,
too, possess lubricating properties. Of the influence or even
presence of aromatic hydrocarbons in lubricating oils
practically nothing is known.
The influence on the viscosity of lubricating oils of their
chemical composition has been studied by Mabery and
Mathews (/. Am. Chem. Soc., 1908, p. 992), who showed
that a low hydrogen content is related to a high viscosity.
Dunstan and Thole (J.I.P.T., 1918, p. 191) consider that
" a lubricating oil should contain a certain proportion of
unsaturated hydrocarbons, as large a proportion as is
compatible with not too much susceptibility to oxidation,
polymerization, gumming, and reactivity."
Mineral lubricating oils from the point of view of manu-
facture fall into two main groups, (a) residual oils, and
(b) distillate oils.
(a) The residual oils may be further divided into two
classes: (i) the black axle oils which are unfiltered and
untreated, made from either naphthene or paraffin base
crudes by concentrating down to the required viscosity.
Typical analyses of such oils are —
A. B. c.
Specific gravity at 15° C. . . 0*896 0-952 0-955
Flash-point, P.M. °C 230 233 190
Fire test °C . . 280 270 220
Viscosity, Kngler, at 50° C. . . 21 24 35
„ at 100° C. . . 3-3 2-7 3-3
(2) The cylinder stocks made from certain paraffin wax
base crude oils, notably those of the Appalachian fields.
These cylinder oils, which are largely used for steam cylinder
LUBRICATING OILS 275
lubrication and for blending with distillate oils for motor
cylinder and other uses, are characterized by high flash-points,
and by a good viscosity curve, i.e. a relatively less falling off
of viscosity with increase of temperature, than that evidenced
by other classes of oils. They appear on the market as
steam-refined cylinder stocks and as filtered cylinder
stocks, the latter being obtained from the former by nitration
through some form of fuller's-earth.
Typical analyses of cylinder stocks—
A. B. c. D.
Specific gravity at 15° C. . . 0*890 0-902 0*884 0*892
Flash-point P.M. °C. . . 265 280 240 260
Fire test °C. . . . . 324 320 300 315
Viscosity, Engler, at 50° C. 27 29 17*5
100° C. 4*1 4*1 3*2
Red wood I. at 100° F. — — 1800
at 200° F. 144
(b) The great majority of mineral lubricating oils belong
to the second category. The manufacture of these oils has
already been described. They may be further subdivided
roughly into two classes, viz. (i) those derived from paraffin
wax base oils, (2) those derived from naphthenic base oils, but
as crude oils vary so greatly oils of all grades intermediate
between these two types are found. These two classes of
oil differ to some extent in their properties. For oils of the
same viscosity the specific gravity of the naphthenic oil is
the higher, and the flash-point the lower. Moreover, oils of
the naphthenic type show a greater falling off of viscosity
with increase of temperature (Fig. 42).
It is generally held that the more gentle gradient of the
viscosity curves of the oils derived from paraffin base crudes
is a point in their favour, but this view is by no means
proved.
The viscosities of all lubricating oils at high temperatures,
say 200° C., approximate very closely to each other. The
differences in viscosity of various oils are more marked the
lower the temperature (Fig. 43).
LJ
CO
20
3O 5O 1O SO
TEMPERflTURE IN °C .
FIG. 42. — Curves showing relation of viscosity to temperature
for lubricating oils : from paraffin base crudes ;
from naphthene base crudes
1000
800
I600
4.0O
200
SOY
FOR
R h
iOLT VISC3SITV CtRVES
LUBRICRTIMQ Oll_S
PTHENE BflSE CR
FROM
DC.
100 130 160
TEMPERflTUPE.T.
ISO 210
FIG. 43. — Curves showing relation of viscosity to temperature
for four oils of the same type.
LUBRICATING OILS 277
The specific gravity of lubricating oils is a property
which has no direct significance. Indirectly, however, it
indicates the origin of the oil, as for any definite viscosity at
temperature t° the specific gravities of oils derived from the
paraffin wax base crudes are lower than those of oils from
naphthene base crudes.
The flash-point of a lubricating oil is usually specified.
This property perhaps has some significance, as an unduly
low flash-point might indicate careless fractionation or
possibly overheating during distillation with the result that
cracking had taken place. This latter might be taken to
indicate instability of the oil at high temperatures, and there-
fore the unsuitability of the oil for certain classes of work.
In general, however, the flash-point has no intrinsic signifi-
cance. As is the case with specific gravity it may indicate
the origin of the oil ; on the contrary, it undoubtedly bears
some relation to the volatility of the oil, or the loss by
evaporation at high temperatures, but if such a factor be of
importance, then it is much better to carry out a specific
test on this point rather than rely on inferences drawn from
the flash-point.
In the case of oils to be used for the lubrication of internal
combustion engines a test which could indicate the degree
of resistance to carbonization in the cylinder would be of
value. Unfortunately, no such test, which gives reliable
figures which may be interpreted in terms of actual practice,
is known. The nearest approach to such a test is perhaps
the coking test as carried out by the Conradson method
(/. Ind. and Eng. Chem.> vol. 4, p. 903).
Garner (J.I.P.T., 1921, p. 98) expresses the opinion that
" the rapid carbonization of oil, i.e. the coking value, will
be a more important factor in the testing of lubricating oils
for internal combustion engines than the gradual carboniza-
tion at lower temperatures," basing this opinion on the
supposition that the major part of the oil which gets into
the combustion space is in the form of a fine spray. This is
very much open to doubt. Certainly the Conradson test does
not give reliable indications as to the ease of carbonization
278 PETROLEUM AND ALLIED INDUSTRIES
in many cases (Circular, Bureau of Standards, U.S.A.,
No. 99, " Carbonization of I/ubricating Oils"). It is quite
possible that the so-called carbon deposits which form on
the pistons of automobile engines are due to cracking of
the lubricating oil, but they may also be due to oxidation.
Waters has devised a test (Bureau of Standards, Scientific
Papers 1532160, Technologic Papers 4273, and Circular 99)
based on oxidation, but so far this test also has not
yielded results comparable to those obtained in actual
practice.
The ash of lubricating oils for use in internal combustion
engines should naturally be as low as possible. Distilled
oils should yield no appreciable ash and filtered residual
cylinder oils should not yield more than 0*02 per cent.,
although higher figures than these are often found.
Pure mineral oils should be free from soaps, the presence
of which may indicate inefficient washing after the refining
process. The presence of such soaps may give the oil a
stringy character, which is usually objected to by buyers,
although it does not necessarily impair the lubricating
qualities of the oil. In certain cases, indeed, aluminium
oleate is added to increase the consistency, and soaps are
normal constituents of greases. Oils containing soaps will
more readily emulsify with water than will pure mineral
oils. For many purposes, particularly in the case of forced
feed systems of lubrication as in the case of turbines, an
oil which will resist emulsification, i.e. which has a good
demulsibility, is necessaty.
For general lubricating work a very large number of
lubricating mineral oils are made, and the number is still
further increased by blends with fatty oils. For a few
specific purposes oils of special character are required. For
the general lubrication of marine engines heavy mineral
oils, blended with from 20 to 30 per cent, of a blown vege-
table oil such as rape, are usual.
For automobile cylinder lubrications blended oils, con-
taining filtered cylinder stock but no fatty oils, are used.
Such oils should be resistant to carbonization, but a means of
LUBRICATING OILS 279
satisfactorily measuring this property in the laboratory is
still to be devised.
For air compressors oils resisting oxidation must be
selected and for refrigerating machines naturally oils of
low cold test.
Oils for turbines should be pure mineral oils free from
any trace of organic acid, so that they resist emulsifying
with water. A type of oil not strictly a lubricant, but similar
in character, which may be noticed here is transformer oil.
Transformer cases are rilled with oil, as oil is a better con-
ductor of heat than air, and so dissipates more quickly the
heat generated, and for good insulation purposes. The
requirements of a good transformer oil are —
(1) It must have a good dielectric strength. It should
not break down at less than 22,000 volts when tested between
the flat surfaces of two parallel discs i inch diameter and
TJo inch apart ; or not less than 40,000 volts when tested
between two 12*5 mm. spheres 5 mm. apart.
(2) It must be quite free from moisture, as this causes
very serious falling off in the dielectric strength. As little
as 0*005 Per cent, of water will reduce the breakdown
voltage by 50 per cent.
(3) It should have a low viscosity, about 8° Bngler at
20° C. or 2-5° Engler at 50° C.
(4) It should be pale in colour consequent upon intensive
refining.
(5) It must be pure mineral oil neutral in reaction.
(6) It should have a high fire test, over 170° C.
(7) It should be resistant to oxidation, i.e. should give
a good " sludging test."
This " sludging " is one of the main troubles. The sludge
always contains oxygen. A sludging test has therefore been
designed based on the behaviour of the oil when oxygen is
bubbled through it for several hours under fixed conditions.
A special type of lubricating oil is medicinal oil. This
is nothing more or less than a highly refined oil of moderate
viscosity. Various specifications for this product have been
drawn up by the pharmacopoeia of various countries. The
2So PETROLEUM AND ALLIED INDUSTRIES
specific gravity usually lies between 0*870 and 0*920 at 15° C.
The oil must be colourless, odourless, and tasteless, have no
fluorescence, be neutral in reaction, leave no ash on ignition,
must separate no paraffin wax at o° C., and must show only
a slight colour after shaking for five minutes with twice its
volume of a mixture of nitric and concentrated sulphuric
acids in the proportions of three to one. The viscosity
should be about 300 Saybolt at 100° F. (16° E. at 20° C.,
105 R.I at 100° F.).
GENERAL REFERENCES TO PART VIIL, SECTION F.
Archbutt and Deeley, " Lubrication and Lubricants." C. Griffin and Co.
Battle, " Industrial Oil Engineering." C. Griffin and Co.
Hurst, " Lubricating Oils, Fats, and Greases." Scott, Greenwood
and Co.
Thomsen, " Practice of Lubrication." McGraw Hill Book Co.
SECTION G.— ASPHALTS
IN the early days of the industry the crude oils first worked
in America were of the paraffin base type. Those of the
European and Asiatic fields later developed, though largely
of naphthene base, contained relatively little asphalt,
so that the distillation residues were liquid and suitable for
fuel. Only comparatively recently did the heavy Mexican
crudes with their large asphaltic content appear on the
scene. Strangely the ever-extending use of light petroleum
tractions for motor transport has brought about a demand
for the heaviest constituents, viz. the road oils and asphalts.
The necessity for good roads which can stand up to modern
heavy traffic, and the superiority of petroleum asphalts for
this purpose is being generally recognized. Moreover, the
general tendency of the coal carbonizing industry towards
vertical and even low-temperature retorts, renders the coal
tar available less suitable than formerly for road-making
purposes.
By far the most important application of the asphalts
is in connection with road making or paving in one form or
another. The application of the naturally occurring asphalt-
impregnated rocks for road surfacing has already been
described, as has also the application of the naturally occurring
asphalts of Trinidad and Venezuela, together with the
petroleum residual asphalts for the same purpose (Part V.,
Section B).
Some idea of the extent to which asphalts are used may
be gleaned from the following figures : The total consump-
tion of asphalt of all kinds in the United States for 1919 was
1,443,289 tons. About 86 per cent, of this was manufactured
from petroleum ; native asphaltites and pyrobitumens
281
282 PETROLEUM AND ALLIED INDUSTRIES
were responsible for 2*3 per cent., and natural asphalts from
Trinidad and Venezuela for 67 per cent. (Hubbard, Chemical
Age, New York, August, 1921). It is estimated that the
asphalt used in the United States for road construction alone
during 1921 amounted to 634,000 tons. The present annual
consumption of asphalt for the roofing industry in the United
States is estimated at 625,000 tons, so that these two
outlets alone account for nearly 90 per cent, of the total
consumption.
Apart from road construction, asphalts are used in
connection with the following : impregnated fabrics for
roofing, flooring, waterproofing and insulating purposes,
also paints, varnishes, japans, pipe-dipping compounds,
acid-resisting compounds, etc., etc.
In the manufacture of " roofing felt " two distinct
operations are necessary, viz. " impregnation " and " sur-
facing." For impregnating, a material of penetration not
more than 60 at 77° F. and melting point from 100-160° F.
(ring and ball method) is usually employed. Native or
prepared asphalts, also products such as wood-tar pitch,
rosin pitch or fatty-acid pitch, may be used, fluxed if necessary
to the required consistency by means of soft asphalts or
flux oils. Such impregnating mixture should naturally
have a flash-point well above the working temperature for
impregnation, which may be as high as 200° C. It should
also contain a large percentage soluble in 0*645 petroleum
ether (malthenes). For surfacing or for cementing together
several layers of impregnated fabric into a composite sheet,
similar mixtures, but of a somewhat higher melting point
and consistency are used. Such mixtures should possess
the following characters : penetration from 10 to 50 at
77° F., melting point not below 160° F. (ring and ball),
low volatility and high flash-point (as above) . The weather-
resisting properties are apparently improved by the admix-
ture of fatty substances, also of opaque material such as
graphite or lampblack, which act as absorbers of the
actinic rays.
The action of " weathering " on asphalts has been studied
ASPHALTS 283
by Hubbard and Reeve (J. Ind. and Eng. Chem., vol. 5, p. 15)
and L,ewis (7- Ind. and Eng. Chem., vol. 9, p. 743). They
find that the changes consequent on weathering are due to
evaporation, oxidation to form oxidized products, elimina-
tion of hydrogen by oxidation, and polymerization. Exposure
to weather has the following effects : the penetration,
melting point, flash-point and fixed carbon content all
increase, while the ductility, adhesiveness, solubility in
carbon bisulphide and in 0-645 petroleum spirit all diminish.
This is in agreement with the gradual change known as
inspissation, the action of which in nature is inferred from
the relations of the natural asphalts to the asphaltites and
pyrobitumens.
The impregnated fabrics are manufactured simply by
running the material through a bath of the melted impreg-
nating material. Roofing felt will absorb about 130 per cent,
by weight of asphalt. The surface of the finished material,
after treating with the surfacing coat, may be further
coated with talc, sand, or even fine pebbles -according to
taste. For a full description of the method of manufacture
of roofing felt, asphalt shingles and their applications, the
reader is referred to Chap. XXV. of Abrahams' excellent
book on " Asphalts and Allied Substances " (D. van
Nostrand Co.).
Asphalt saturated felt is also used as a ' ' substitute for
linoleum," in which case it merely acts as a support for a
layer of the linoleum composition on the upper surface.
Impregnated cotton fabric is also largely used for " damp-
proof courses " in buildings. " Insulating papers " are also
largely made by impregnating suitable papers with asphalt
mixtures as used for roofing felt, also with other petroleum
products, such as paraffin wax and cylinder oils. Such
papers are used for insulating refrigerator vans, ice chests,
etc., also for electrical purposes. Insulating tape is made
in a similar way.
Asphalt enters into the composition of "pipe-dipping
mixtures," used to protect iron or steel piping which is liable
to exposure to damp soil containing corrosive salts, and to
284 PETROLEUM AND ALLIED INDUSTRIES
electric currents. The dipping mixture used must be
durable and tough and adhere well to the metal. The pipes
to be dipped are heated to about 200° C., and then immersed
in a bath of the asphalt at the same temperature. On
withdrawal, they are heated or baked before cooling. A
number of " bituminous paints and varnishes " are on the
market and are used for a variety of purposes, such as water-
proofing walls, protecting wood and metal surfaces, etc.
Bituminous paints are merely solutions of asphalt in suitable
solvents, which on evaporation leave the asphalt distributed
over the surface. Bituminous varnishes contain also vege-
table drying oils which contribute to the drying and harden-
ing of the film, as in the case of ordinary oil paints. The
so-called " mineral rubber," is also a petroleum product.
The best grades consist of mixtures of blown asphalt and
gilsonite, the gilsonite being usually mixed with the asphalt
before the blowing operation. These mineral rubbers are
used for incorporating into natural rubber with which they
are masticated. C. O. North (Chem. and Met. Engineering,
1922, p. 253) has investigated this subject and has found
that mineral rubber when mixed in in proportions from
3 to 15 per cent, has a beneficial effect on the properties
of the rubber. In proportions greater than 15 per cent.,
however, it affects the rate of recovery of the rubber.
GENERAL REFERENCES TO PART VIII., SECTION G.
Abrahams, " Asphalts and Allied Substances." D. van Nostrand Co.
Kohler und Graefe, " Natiirliche und Kiinstliche Asphalte." Vieweg
und Sohn, Braunschweig.
PART IX.— THE TESTING OF PETROLEUM
PRODUCTS
As the subject of the testing of petroleum products is fully
dealt with in numerous books and publications, the descrip-
tion of detailed methods here would serve no useful purpose.
It is proposed, therefore, merely to present a few general
considerations on the subject together with a few data
dealing with the relation of several of the instruments in
general use to each other.
The tests applied to petroleum products fall at once
into two categories, (a) those which are applied according to
the methods of exact chemical analysis, and (b) those which
are applied by means of apparatus of specified dimensions
operated in a specified manner.
Under the former heading fall such determinations as
elementary organic analysis, percentage of sulphur, the
determination of certain physical constants, solubilities,
and so forth. Under the latter heading fall all the determina-
tions of the values of such properties as flash-point, viscosity,
distillation range, colour, illuminating power, melting point,
penetration, ductility, and the like.
The fact that the bulk of the determinations usually
carried out are of such an empirical nature has brought
about a position of chaos in this respect. Co-operation
between large firms and between petroleum organizations in
various countries has been practically non-existent, with the
result that there are almost as many instruments in use for
testing flash-points, for example, as there are countries. Prior
to the great war an International Petroleum Congress had
been formed, one of the aims of which was the standardizing
285
286 PETROLEUM AND ALLIED INDUSTRIES
of methods of testing, but this organization has unfortunately
become defunct. The subject has, however, recently received
the attention of the American Society for Testing Materials,
a society which has already done much work, and is now
also receiving the attention of the recently formed Standardi-
zation Committee of the Institution of Petroleum Technolo-
gists in this country. If these two bodies work together,
a much desired uniformity in testing methods may be brought
about (Brame, Presidential address to Inst. of Pet. Tech.,
March, 1922). Until this much-to-be-desired state of
affairs results, a few words dealing with the subject generally
may not be out of place.
Of the determinations which fall in the first category
mentioned above little need be said. The usual physical
constants can be determined with accuracy by the usual
methods. Even in the expression of such a simple and
important constant as specific gravity there is, however,
no uniformity. In America the arbitrary Beaume scale is
used. In other countries there is often much confusion as
to whether the specific gravity is referred to water at 15° C.,
60° F., or 4° C. This may lead to disputes in the determina-
tion of the weights of cargoes of oil. Moreover, the figures
used as coefficients for converting the specific gravity at any
temperature t° to the standard temperature of reference
are neither accurately determined nor even generally agreed.
The elementary chemical analyses may be made in the usual
way. Sulphur may be estimated by the calorimeter bomb,
and in the case of light products, such as benzines and
kerosenes, may be accurately estimated by one of the methods
based on burning the oil in a current of air, absorbing the
resulting sulphur dioxide and estimating it as sulphate or
otherwise (lyomax, J.I.P.T., 1917, p. 19 ; Bowman, J.I.P.T.,
1921, P- 334 ; Esling, J.I.P.T., 1921, p. 83).
Methods of estimating the percentage of the various
chemical compounds or even classes of hydrocarbons present
in a crude oil or even in a light distillate are by no means
reliable and yield only approximate results. Olefines may
be estimated by removal by sulphuric acid, by bromine or
THE TESTING OF PETROLEUM PRODUCTS 287
iodine absorption, or by reaction with potassium permanga-
nate, but all these methods give unsatisfactory results
(Chavanne and Simon, Comptes rendus, 1919, pp. 70, in ;
Lomax, J.I.P.T., 1917, p. 22 ; Bowrey, J.I.P.T., vol. 3,
p. 287). The question of determining the percentage of
aromatic, naphthene, and paraffin hydrocarbons in a motor
spirit is one of importance. Perhaps the best and simplest
method so far evolved is that of Tizard and Marshall (J. S.C.I.,
vol. 40, p. 20T) (vide also p. 26). While this method gives
reliable values for the aromatics, the values indicated for
naphthenes are approximate only. In the case of products
containing compounds of high molecular weight, methods
are even less satisfactory. Asphalts are examined according
to their solubility in various chemical solvents, and the
existence of bodies termed asphaltenes, carbenes, malthenes,
etc. , is thereby inferred. The figures so obtained are doubtless
of some value, as they can be correlated with variations in
the method of manufacture and, moreover, give useful
indications as to the origin of the product. How dependent
these values are on conditions is well exemplified by the
work of Mackenzie (/. Ind. and Eng. Chem., 1910, p. 124),
who showed that the amount of carbenes found largely
depends on the exposure to light during the estimation.
When methods of the second category are considered,
very great diversity, both in apparatus and methods of
testing, are at once obvious. In the case of the examination
of benzines for range of boiling points several methods
have been largely used. Among these may be mentioned the
Engler and the Ubbelohde, with their many modifications.
In the case of the Engler test, the flask and its contents
are weighed, and after distillation to a definite temperature,
the contents are again weighed, the percentage distilling up
to that temperature being determined by the loss of weight.
The distillation in this case is interrupted at the temperature
in question, and after the flask has been allowed to cool
somewhat, heat is again applied until the temperature of
the vapour again reaches the point in question. This opera-
tion is repeated several times (usually three). This method
288 PETROLEUM AND ALLIED INDUSTRIES
differs fundamentally therefore from the Ubbelohde method
in general use in that the distillation in the latter case is
carried on continuously, the percentages boiling over up to
any definite temperatures being expressed in volumes. The
Bngler method usually yields results about 5 per cent,
higher than those given by the Ubbelohde method, in
distilling to 100° C. The liability to personal error in the
Bngler method is great, moreover, as the percentage distilling
over is determined by loss of weight and not by measuring
the distillate collected, the very volatile gaseous or noncon-
densable fractions which would otherwise be lost are included.
Something is, of course, to be said on both sides of this
question. I,omax (J.I.P.T., 1917, p. 7) gives figures com-
paring the Engler and Redwood methods, this latter method
being to all intents and purposes identical with the Ubbelohde
method (except in so far as the method of determining the
initial boiling point is concerned).
Redwood. Engler.
Redwood. Engler.
Percentage to 100° C.
to 125° C
to 150° C
Final boiling point
Time for test (minutes)
5 II
60 65
89 90
176 175
5° 90
8 16
61 67
9° 93
176 174
55 90
A form of apparatus used in France, not only for benzine
but also for kerosene and fuel oils, is the IvUynes-Bordas. It
consists of a copper retort of special design enclosed in an
iron casing, connected to a metal water-cooled condenser.
In the case of benzine the thermometer is immersed in the
vapour, but when distilling kerosene or fuel oils it is placed
in the liquid. As compared with the Ubbelohde test for
benzine the lower fractions distil at slightly higher tempera-
tures and the higher fractions at slightly lower temperatures.
The figures given below illustrate a comparative test with
the two types of apparatus : —
Luynes Bordas
Ubbelohde at
at temperature °C.
temperature °C.
72-6
67'3
87-5
84-8
1047
106*9
IJ3
115-2
I58-3
160*4
175
i75'5
THE TESTING OF PETROLEUM PRODUCTS 289
Volume distilled
over (per cent.).
5
20
45
55
90
95
The apparatus is very sensitive to changes in the rate of
distillation. With kerosene the distillation results of the
two methods show greater divergence. The method of
Ubbelohde as modified by the American Society of Testing
Materials (E. W. Dean, Bureau of Mines, Technical Paper 166),
may be recommended for general adoption.
The determination of the flash-point of kerosenes is a
subject which has received much attention. In the British
Empire the Abel method is the standard, on the Continent
the Abel-Pensky modification is used, the personal factor
of the Abel apparatus being eliminated by the use of a dock-
work device. In the United States several flash-point
testers are in use such as the Tagliabue closed cup, the Foster
and the Elliot. Allen and Crossfield have recommended
a modified Abel-Pensky apparatus (Bureau of Mines,
Technical Paper 49) . Taking the Abel-Pensky as a standard,
the Tagliabue closed cup gives results 3° C. higher ; the
Foster 6° C. higher, and the Elliot 5° C. lower. The
German type of Abel-Pensky gives results 37° F. higher
than the; Abel. In France the Luchaire type of flash-point
tester is in general use.
For the testing of colour many forms of instruments
are in use. They may be divided roughly into two classes,
(a) those which match the tint of a definite thickness of oil
with various standardized coloured glasses, (b) those which
match the tint of a standard coloured glass by varying
the thickness of the layer of oil looked through. To the
former class belong the instruments of I^ovibond and Wilson,
to the latter those of Say bolt and Stammer. For detailed
descriptions of these instruments the reader may be referred
p. 19
2(jo PETROLEUM AND ALLIED INDUSTRIES
to Campbell's " Petroleum Refining for lyovibond," Kansas
City Testing laboratory, Bulletin 14 for Saybolt, and to
Holde, " Die Untersuchung der Mineralole und Fette,"
for Stammer. The L,ovibond instrument is also supplied
with a fine range of glasses of yellow and red tints, in addition
to the standard glasses for kerosene ; the Stammer has the
advantage that the thickness of the column of liquid under
observation may be varied either way as often as required.
The trade terms used to designate the colours of kerosenes
are Water- white, Superfine- white, Prime- white and Standard-
white. These terms have unfortunately not precisely
equivalent values on different instruments.
Fig. 44 shows at a glance the comparative readings of
WW300J
w
vy.
250 "
w.
W.W
1
-
20_
Sw.W.200_I
1-5
150^
-
S<4,
Vy s*-w-
-2
looj
-
_3
PW. -"
'°-7
5,
vv.
«
Sd.W.50_I
54
_5
.
°_E
Sd.W.
PW.
6
-
5.1
S«L
w
_7
-
IO_S
SdirV.
~ 8
o__
FIG. 44. — Comparative colorimeter readings, using benzine and
kerosene.
the four types of instrument mentioned. Francis (Nat* Pel.
News, June 10, 1921, p. 34) gives a useful comparison between
the Saybolt and I^ovibond instruments, and compares this
latter type also with the Union Petroleum Colour Standards
THE TESTING OF PETROLEUM PRODUCTS 291
and colorimeter used in the United States for the testing
of lubricating oils.
There are also numerous types of instruments in use
for determining the flash-points of heavy oils, fuels, lubri-
cating oils and so forth. The order of accuracy of these
instruments is not so great as those used for flash-points
at lower temperatures, but the need for accuracy is not so
great. The type in most general use is the Pensky Marten ;
the Cleveland open cup and the Gray tester are in use in
the United States.
The influence of water on the flash-point must be noted,
as unless the oils to be tested are dry, errors of as much as
20° F. in the flash-point may be made, the wet oil giving the
higher value. The presence of i per cent, of water usually
renders the determination impossible. Even with dry oils,
successive determinations by the same observer may differ
by as much as 7° or 8° F.
A large number of instruments have been designed for
the testing of viscosity. Owing to thegreat range of viscosities
to be determined, varying from that of a light spindle oil
to that of a heavy cylinder, thick fuel or flux oil, one
instrument of any type cannot well cover the whole range.
For the more viscous oils, therefore, special types have been
designed. There is, however, great lack of co-operation in
this matter ; not only do the instruments in use in different
countries differ, but even the mode of expressing the results
obtained.
The absolute viscosity of an oil is " the force which is
required to move a unit area of plane surface with unit
velocity relative to another parallel plane surface from which
it is separated by a layer of the oil of unit thickness "
(Herschel, U.S.A. Bureau of Standards, Technologic Paper,
No. 100). The unit of absolute viscosity is termed the
" poise."
F being the force in dynes required to slide two parallel
plates, each of area a square centimetres, over one another
292 PETROLEUM AND ALLIED INDUSTRIES
at a velocity of v centimetres per second, when separated
by a layer of oil of absolute viscosity p and thickness a
centimetres.
The absolute viscosity of water at 20° C. is 0*01005 poises.
Specific viscosity is the ratio between the absolute viscosity
of the substance and that of the absolute viscosity of
water at the same temperature. In practice, however, the
absolute viscosity of water at 20° C. is taken as the reference
figure.
The absolute viscosity of an oil is determined in practice
by the capillary tube method (Archbutt and Deely, " Lubri-
cation and lyubricants," p. 155). For commercial use,
however, relative viscosities only are usually required and
these are determined by a number of different instruments,
most of which depend upon the measurement of the time of
flow of a definite volume of the liquid through an orifice of
definite dimensions under definite conditions of temperature
and head. The instruments in most general use are the
Engler on the Continent, the Redwood in England, and the
Saybolt in the United States. For very viscous oils a special
Redwood Admiralty type, usually known as Redwood II.
possessing a much larger orifice is in use in England, and a
Saybolt Furol instrument in the United States. Descrip-
tions of these instruments are given in most of the books
dealing with the testing of petroleum products, e.g. Battle,
" Industrial Oil Engineering," Griffin and Co. These instru-
ments give values which are approximately proportional
to actual viscosities particularly when oils of high viscosity
are examined. When mobile liquids are examined the rate
of flow depends by no means entirely on the viscosity, as
it is influenced by the necessary increase in kinetic energy
of the liquid, while flowing through the nozzle, which
naturally impedes the flow. This kinetic effect, how-
ever, becomes negligible when the viscosity of the liquid
exeeds about 10° Engler at the testing temperature. As
a consequence of this kinetic effect, conversion factors
for translating the reading of one type of commercial
viscosimeter into the equivalent reading of another type
THE TESTING OF PETROLEUM PRODUCTS 293
are not constant, but vary somewhat with the viscosity of
the oil.
With this reservation a table can be drawn up giving the
relative values of viscosities as determined by the various
instruments, at the same temperature. In order to calculate
the viscosity of an oil on another instrument at a different
temperature, a knowledge of the viscosity curve showing
the relation of viscosity to temperature for that particular
oil would be necessary.
The following figures may be taken, therefore, only as a
rough guide : —
Engler seconds. Redwood I. seconds. Saybolt seconds.
56 21'5 32H
66 34-6 39-3
75 39'8 45'5
85 457 52-5
100 54-3 63-0
130 7i7 83-5
160 89*1 !04'4
200 111*9 131*6
250 140-3 165-5
300 168-5 J98'8
350 197-0 233-2
400 225-5 266-5
500 282*0 334-0
600 339*0 400 'o
The factors for converting Saybolt to Engler will thus be seen
to vary from 1*73 for an oil of about i° Engler to 1*50 for an
oil of about 10° Engler (i° Engler equals approximately
53 seconds, but varies somewhat with different instru-
ments).
As approximate values the conversion factors for
Redwood I. to Redwood II. may be taken as 0*091 and for
Saybolt to Saybolt Furol as 1*05 (Herschel, loc. cit.). The
readings of the commercial instruments can be converted
into absolute viscosities by the formulae given by Herschel
(U.S. Bureau of Standards, Circular No. 112).
294 PETROLEUM AND ALLIED INDUSTRIES
Absolute viscosity
= Sp.gr.( 0-00213 Saybdt -
= Sp. gr. ( 0-00147 Engler
= Sp. gr. ( 0-00260 Redwood — _ , , T )
V Redwood I. /
The calculation of the viscosities of mixtures of oils is
almost impossible unless the two oils used are of viscosities
very slightly different, a case seldom met with in practice.
Viscosity numbers are not additive figures. The influence
of the lower viscosity oil is always much greater than would
be expected. This subject has been investigated by Dunstan
and Thole (" The Viscosity of liquids/' p. 39), Espy
(" Petroleum," 1919, p. 27), Herschel (Bureau of Standards,
Tech. Paper 112), and others. A summary of their work
may be found in Hamor and Padgett, " The Examination
of Petroleum," p. 357.
The tests usually applied to the heavy asphaltic products
of petroleum are largely of an even more empirical nature
than those above described. Two types of penetrometers
are in use, that of Dow and that of the New York Testing
laboratory, but both operate on the same principle, and give
practically the same results under similar conditions.
Several methods are in use for the determination of the
melting point of asphalts. As such substances gradually
soften and have no definite melting point any test must be
quite empirical. A comparison of the chief methods is
given in Chem. and Met. Engineering, 1919, p. 81. The
ring and ball method gives consistent readings, but the
personal error may be large. The Kramer and Sarnow
method gives less consistent results and is complicated in
operation. This test gives results from 15° to 25° F. lower
than those given by the ring and ball method.
The total bitumen is given by the solubility in carbon
bisulphide. Any organic matter insoluble in carbon
THE TESTING OF PETROLEUM PRODUCTS 295
bisulphide is often erroneously termed free carbon. It may
be free carbon in some cases, but it must be remembered
that the kerotenes, the chief components of asphaltic pyro-
bitumens, are insoluble in carbon bisulphide. The amount
insoluble in petroleum ether (sp. gr. 0*645) is usually deter-
mined, those constituents which are soluble in this solvent
being termed malthenes. As the solvent powers of petroleum
ethers depend on their chemical composition (aromatics
and naphthenes being better solvents than paraffins), it
is as well to use only petroleum ether composed entirely
of paraffins. The constituents which are insoluble in
petroleum ether are often termed asphaltenes, but it is better
to restrict this term to the constituents insoluble in alcohol
or alcohol-ether mixture. The constituents of some asphalt-
ites which are soluble in carbon bisulphide, but insoluble
in carbon tetrachloride are termed carbenes. Carbenes
are not found in petroleum asphalts unless they have been
overheated during manufacture. The presence of more
than 0*5 per cent, of carbenes should be regarded with
suspicion.
Several methods are used for the determination of the
melting point of paraffin wax. Although this is quite a
definite point as compared with the melting point of an
asphalt, the various methods give considerably divergent
results. The British method and the continental method
(ShukofT) are similar in principle. A thermometer is immersed
in a quantity of the melted wax and the cooling curve is
drawn. At the point of crystallization the latent heat evolved
by the crystallizing wax causes a break in the curve, so that
the thermometer remains stationary for a short time. The
temperature at which this occurs is taken as the setting
point. The American method is more empirical. A
thermometer of standard dimensions is placed with three-
quarters of its bulb immersed in melted wax contained
in a bowl 3! inches diameter. The temperature is noted when
a film of solid wax extends from the sides of the bowl to the
thermometer. The American method gives results 3° F.
above those given by the British method.
296 PETROLEUM AND ALLIED INDUSTRIES
Numerous other tests, some of value, many of little or
no value, are employed. For details of these the reader
must be referred to one of the many books dealing specially
with this subject.
GENERAL REFERENCES TO PART IX.
Hamor and Padgett, " The Technical Examination of Crude Petroleum,
Petroleum Products, and Natural Gas."
Rittman and Dean, "The Analytical Distillation of Petroleum."
Bulletin 125, U.S. Bureau of Mines.
Hubbard, " Laboratory Manual of Bituminous Materials." Wiley and
Sons, New York.
Holde, " Untersuchung der Mineralole und Fette." J. Springer, Berlin.
Graefe, " Laboratoriumsbuch fur die Braunkohlenteer - Industrie."
W. Knapp, Halle.
SUBJECT INDEX
ABSORPTION process for gasoline, 53
Acid sludge, regeneration of, 238
Acid, sulphuric, action of, on petro-
leum, 201
Agitators, 198
Airlift system for raising oil, 81
Albertite, 138
Alcohol, 27, 216, 248
Aniline point method for aromatics,
26, 287
Anticline, 34
Aromatic hydrocarbons in petro-
leum, 22, 287
as motor fuels, 244, 248
in tars, 126
Asphalt, 131
applications of, 142, 281
Bermudez, 132, 143
macadam, 145
manufacture of, 173, 224
rock, 134, 142, 281
Trinidad, 132, 142, 281
Asphaltic pyrobitumens, 2, 131
pyrobituminous shales, 139
Asphaltites, i, 131, 135
BACTERIA, action of, on petroleum,
19,4o
Baling method of raising oil, 73
Bauxite, 202, 214
Benzene. Vide aromatic hydro-
carbons
Benzines, applications of, 241
characters of, 250
manufacture of, 159, 190
Bitumen, 2, 130
Blown asphalts, 227
Burton process, 233
CANDLES, 152, 269
Carbon black, 49
Carbonization of coal, 125
lubricating oils, 277
Casing for wells, 74
Casinghead gas, 47
gasoline, 51
Cementing, 75
Centrifugal method for dehydrating
oils, 94
Ceresin, 150
Charcoal absorption process, 58
Chemical treatment of oils, 196
Chemistry of petroleum, 15, 123,
126, 273
Coal, relation of, to petroleum, 27
carbonization of, 125
Coke, 129
Coking test, 277
Colorimeters, 289
Compressed asphalt paving, 145
Compression process for gasoline, 52
Condensers, 157
Continuous distillation, 163
Core drilling, 69
Cracking processes, 229
Crude oils, 2, 29, 61, 68, 155
Cutting oils, 221
Cylinder oils, 172, 217, 278
DECOLORIZING powders, 202, 239
Dehydrating of crude oil, 93
Dephlegmators, 160, 178
Derricks, types of, 70
Desulphurizing oils, 123, 200
Detonation, 248
Distillate preheaters, 166
Distillation, continuous, 163
of crude oil, 153
of light oils, 1 88
periodic, 155
plant, efficiency of, 184
steam, 173, 179, 189
under vacuum, 170
Drilling methods, 69
EDELEANU process, 16, 205
Elaterite, 137
Electric dehydrating plant, 95
Emulsions, 94, 219
Evaporation, losses by, 84, 88
FATTY acids, 28, 272
Faults in oil-fields, 36
Filter pressing, 210
297
298
SUBJECT INDEX
Fires on oil-fields, 83
Fishing operations, 79
Flash-points, 289
Flowing wells, -80
Fractionating columns, 190
Fuel oils, applications of, 265
characters of, 262
manufacture of, 1 74, 224
GAS. Vide Natural gas
Gas oils, applications of, 258
manufacture of, 159, 225
Gilsonite, 135, 146
Glance pitch, 136
Grahamite, 137, 146
Greases, 222
Grouting, 145
Gushers, 80
HALL'S cracking process, 234
Heckmann column, 191
Helium, 30, 58
History of petroleum, 6
Hydrogenation methods, 235
IMPSONITE, 139
Inspissation, 101
Internal combustion engine, effi-
ciency of, 246
KAPAK, 146
Kerogen, 98, 121
Kerosene, 159, 252
LIGNITE, 127
Lubricating oils, applications of, 271
chemistry of, 273
manufacture of, 208
MANJAK, 136
Medicinal oils, 221, 279
Montan wax, 101, 127, 150
Motor spirits, characters of, 241
Mud volcanoes, 43
NAPHTHENES, 22, 248
Natural gas, casinghead, 47
composition of, 49
fields, 44
production of, 43
Neutral oils, 218
OIL shales, characters of, 97
mining of, 106
retorting of, 1 1 1
testing of, 108
Ozokerite, 3, 20, 148
PARAFFIN WAX, manufacture of, 208
applications of, 268
Paraffins, 3, 19, 121, 126
Peat, 128
Penetrometer, 144, 226
Percussion methods of drilling, 70
Petrolatum, 221
Petroleum, chemistry of, 15
geology of, 31
history of, 6
jelly, 221
origin of, 38
production of, 9
Pipelines, 89
Porosity of oil rock, 33
Pumping oil wells, 81
Pyrobituminous shales, 100, 139
Pyropissite, 128, 151
REDISTILLATION of light fractions,
188
Refrigerating plant, 209
Retorts for shale distillation, 115,
228
Ring packings, 193
Rittmann process, 234
Rock asphalt, 134, 142
Rod wax, 221
Rotary system of drilling, 77
SALINE domes, 35
Sand pump, 73
Shales, characters of, 97
mining of, 107
retorting of , no
testing of, 108
Sharpies process, Q.J.
Shooting wells, 82
Sludge acid, 238
Spudding, 73
Steam refined cylinder oils, 217, 275
Stills for crude oil, 155
tubular for crude oil, 173
Storage of oil, 85
Sulphur in petroleum, 24, 197
Sulphuric acid, action of, 195, 201
Swabbing, 82
Sweating process, 212
TANKS, 86
Tank steamers, 90
Tar, 4, 125
Terpenes in petroleum, 24
Testing of products, 285
Topping plants, 180
Torbanite, 99, 103
Transformer oils, 279
Tubular stills, 175
Turbine oils, 279
SUBJECT INDEX
299
VACUUM distillation, 170
Viscosity, 291
Vulcanized asphalts, 227
WASTE on oil-fields, 43, 83
Waste products, utilization of, 237
Water, flush system, 77
Water gas plant, 260
shutting off. 75
Wax. Vide Paraffin wax
Wax tailings, 4, 159
White spirit, 242
Wild catting, 36
WOrtzilite, 138, 146
NAME INDEX
AlSINMANN, 273
Alabama, 61
Alamo, 63
Alberta, 24, 44, 64, 135
Albrecht, 16
Algeria, 25, 133
Allen, 289
Alsace, 60, 65, 82
Amend, 201
Anderson, 58
Appalachian, 32, 45, 61, 217, 274
Apscheron, 10
Arabia, 133
Archbutt, 273
Argentine, 64, 133
Assam, 65
Athabasca, 33, 64, 135
Australia, 136
Austria, 104, 133
Autun, 104
BAICOI, 65
Bailey, 109
Baker, 89
Baku, 10, 32, 273
Balachani, 64
Barbados, 136
Barringer, 92
Baskerville, 238
Batoum, 89
Beeby Thompson, 33, 44, 83, 266
Beilby, 114, 117
Bermudez, 32, 131, 132, 134, 143,
144
Berthelot, 38
Bibi Eibat, 64
Bohemia, 150
Bolivia, 64
Borneo, 19, 22, 60, 66, 215
Botkin, 120
Bowman, 286
Bowrey, 18, 287
Brame, 286
Bransky, 16
Brazil, 64, 105
Breitenlohner, 229
Briant, 39
Brooks, 201
Broxiere les Mines, 104
Brunck, n
Bryson, 115
Bulgaria, 104
Burmah, 7, 10, 29, 32, 35, 43, 65,
66, 169, 215, 268
Burney, 118
Burrell, 58
Burton, 233
Bury, 27, 237
Bustenari, 65
Byerley, 226
CADELL, 103
Cady, 58
Caldwell, 107
California, 19, 22, 25, 32, 44, 47,
48, 63, 69, 80, 101, 105, 131, 133,
141, 173, 218, 225
Campina, 65
Canada, 17, 21, 25, 47, 64, 85, 104,
133, 200
Carves, n
Caspian Sea, 7, 43
Castleton, 137
Caucasus, 21, 22, 25, 64
[ Chantour9ois, 38
| Charitschkoff, 16
Chavanne, 26, 287
Cheleken, 148
Chercheffsky, 239
Cherry, 236
China, 7, 105
Coast, 233
300
NAME INDEX
Coates, 24
Colin, 201
Colorado, 62, 98, 105, 106, 137
Columbia, 64, 136
Conacher, 101
Conradson, 258, 277
Constanza, 89
Cottrell, 95, 141
Crichton, 117
Crossfield, 289
Cuba, 8, 131, 133, 134, 137, 139
Cunningham Craig, 39, 41, 99, 101
DALLE Y, 187
Darmois, 17
Daubree, 38
Day, 1 6, 235
Dean, 61, 289
De Chambrier, 83
Deely, 273
De La Haye, 8
Del Monte, 118
Derbyshire, 8, 65
Dewar, 230
Dexter, 47
Divine, 238
Dorset, 104
Drake, 9
Dunod, 239
Dunstan, 201, 274, 294
Dykema, 243
EAST INDIES, 10, 32, 35, 65, 66, 268
Ebano, 63
Edeleanu, 205
Egloff, 236
Egypt, 6, 10, 22, 32, 66, 136
Ellis, 28, 236
Ells, 64, 104
Endle, 231
Engler, 16, 24, 39, 101
Esling, 286
Espy, 294
Esthonia, 104
FISCHER, 27, 28, 41
Forbes-Leslie, 103
France, 8, 65, 104, 131, 133, 134,
288
Francis, 290
Franks, 116
Frasch, 200, 201
Freeman, 118
Friedel, 236
Fyfe, 117
GALICIA, 10, 19, 21, 22, 32, 65, 69,
85, 148, 215, 268
Garner, 277
Gavin, 98, 109
Germany, 133, 216
Gessner, 8
Gilpin, 1 6
Glazebrook, 90
Gluud, 27, 41
Goodwin, 193
Gossage, 187
Graefe, 16
Grand Valley, 106
Greece, 65, 131, 133
Greenstreet, 235
Grosby, 64
Gulf, 62
HACKFORD, 4, 27, 29, 41, 100, 101
Hall, 201, 202, 205, 234
Hancock, 8
Hanport, n
Hardstoft, 32, 65
Harries, 21
Henderson, 117, 210
Herold, 231
Herschel, 291, 293, 294
Higgins, 90, 148
Hill, 109
Hinckley, 58
Holde, 272
Hubbard, 134, 141, 282
Humbolt, 38
Humphrey, 201
Hunt, 39
ILLINOIS, 32, 62
Indiana, 32, 62, 133
Italy, 65, 104, 133
ACCARD, 39
ackfork Valley, 137
apan, 7, 25, 65, 66, 133
ava, 66, 268
ones, 22, 1 02
KANSAS, 44, 47, 48, 58, 62, 105
Kentucky, 50, 61, 105, 131, 133
Kewley, 15
Kimmeridge, 32, 104, 123
Knab, n
Knibbs, 187
Koetei, 66
Kraemer, 24
Krieble, 15, 24, 64, 135
Kubierschky, 194
LANGMUIR, 272
Laurent, 8
Leather, 23
Lessing, 15, 193, 194
Lewis, 283
NAME INDEX
301
Lima, 62
Limmer, 33, 134, 135
Loffl, 28
Lomax, no, 286, 287, 288
Lothians, 103
Louisiana, 35, 44, 50, 62, 133
Luynes-Bordas, 288
Lyder, 103, in, 114
MABERY, 20, 24, 41, 221, 273, 274
Mackenzie, 287
Maclaurin, 118
Maikop, 65
Mansfield, 104
Maracaibo, 131, 132
Marcusson, 24, 151, 273
Markownikoff, 24, 239
Marshall, 26, 287
Matthews, 274
McAffee, 236
McFarland, 58
McKee, 103, in, 114
McLennan, 58
Meigs, 256
Mendelejeff, 38
Meserve, 58
Mesopotamia, 6, 32, 66, 133, 139
Mexico, 10, 19, 32, 35, 41, 63, 68,
80, 101, 131, 133, 136, 139, 144,
169, 173, 200, 224, 225, 268
Midcontinent, 32, 35, 44, 62, 169,
218
Missouri, 133
Moldavia, 148
Montana, 50, 62, 105
Moore, 236, 264
Murdoch, 8
NARANJOS Los, 63
Neal, 50
Nevada, 105
New Brunswick, 8, 101, 103, 104,
138
Newfoundland, 105
New Mexico, 62, 105
New South Wales, 105, 107, 216
New York, 48, 61
New Zealand, 67, 105
Nielsen, 118
Norfolk, 32, 103, 104, 1 06
North, 284
Nova Scotia, 103, 105
Nova Zembla, 101
OBERFELL, 58
Ohio, 32, 44, 48, 61, 62, 101, 200
Oil Springs, 64
Oklahoma, 48, 62, 105, 133, 137,
139, 146
Ollander, 27
Ontario, 32, 44, 64, 69
Orton, 39
PADGETT, 231
Palestine, 136
Pannell, 90
Panuco, 63
Papua, 67
Paris, 239
Parish, 240, 271
Pechelbronn, 65, 82
Peckham, 25
Pennsylvania, 8, 32, 44, 47, 48, 61,
169, 170, 172, 208, 218, 273
Perdew, 109
Perrot, 51
Persia, 6, 10, 19, 25, 33. 65, 66
Peter, 18
Petrolia, 64, 8 1
Peru, 22, 64
Pfaff, 152
Philippines, 131, 133
Pinat, 239
Poelsch, 77
Portlock, 8
Portugal, 63, 133
Potrero, 63
Preston, 90
Prym, 193
Pschorr, 152
Pumpherston, 115
Pye, 247
RAGUSA, 134, 135
Raschig, 193
Redwood, 230, 288
Reeve, 283
Reichenbach, von, 8
Remfrey, no
Ricardo, 20, 246, 247, 248
Richards, 230
Richardson, 141
Riebeck, 9
Rittman, 234
Riviera, 104
Robertson, 236
Rocky Mountains, 62
Rolle, 128
Romany, 64
Ross, 23
Rozet, 38
Rumania, 10, 19, 21, 22, 35, 65, 82,
Rozet, 38
89, 148, 206, 268
Russia, 10, 17, 32, 33, 35, 64, 68,
74, 80, 82, 133, 169, 218
SABATIER, 235
302
NAME INDEX
Saboontje, 64
Sakhalin, 133
Sarawak, 66
Saxony, 10, 127
Schaarschmidt, 28
Schneider, 28
Scotland, 9, 103, 114, 216
Senderens, 235
Seyer, 15, 24, 64, 135
Seyssel, 134, 135
Sharp-Hughes, 79
Sharpies, 94
Siberia, 65, 131, 133, 137
Sicily, 133, 134
Simon, 26, 287
Simpson, 117, 119
South Australia, 137
Southcombe, 272
Spain, 65, 104, 133
Spilker, 24
Spindle Top, 77
Standinger, 231
Steinschneider, 170
Stewart, 117, 122
Stirling, 81
Storer, 39
Sumatra, 19, 66
Surachany, 64
Sweden, 104
Switzerland, 133, 134
Syria, 131, 133
TABASCO, 63
Taranaki, 67
Tasmania, 105, 139
Tausz, 1 8, 21, 27
Tehuantepec, 63
Tennessee, 61
Texas, 32, 35, 44, 48, 62,
105, 133, 173, 218, 225
Thiele, 28
Thiessen, 51
Thole, 274, 294
Thorpe, 230
Thuringia, 150
Titusville, 9
Tizard, 26, 247, 287
Topila, 63
77. 79,
Torbane Hill, 8, 103
Transvaal, 105
Trevor, 105
Trinidad, 8, 32, 63, 133, 134, 137,
143, 144, 225, 281, 282
Trumble, 175
Turkey, 104
Tzintea, 65
UBBELOHDE, 287
Uinta, 135
Ulbrich, 28
United States, 9, 32, 35. 45. 47, 5i.
58, 61, 63, 68, 89, 97, 134, 135,
268
Ural Caspian, 64
Utah, 62, 105, 131, 133, 135, 138,
139, 158
VAL DE TRAVERS, 33, 134, 135
Valenta, 16
Venezuela, 10, 63, 131, 169, 225,
281, 282
Virginia, 44, 48, 50, 61, 105
Virlet d'Aoust, 38
WADS WORTH, 181, 185
Warren, 39
Waters, 278
Wells, 272
West Virginia, 105
Wheller, 102
Wiggins, 84, 88
Wilson, 103
Wirth, 28
Wolgan Valley, 105, 107
Wolochowitsch, 16
Woog, 273
Wooton, 22
Wurtemburg, 104
Wyoming, 32, 50, 62, 105
YENANGYAUNG, 7
Young, 8, 114, 117, 154, 229, 230
ZALOZIECKI, 16
Zanetti, 231
Zante, 7
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UNIVERSITY OF CALIFORNIA LIBRARY