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UNWERSri'Y LIBRARIES

,T 511

imelblau, Harry. Steam jet ash conveyors

Steam Jet Ash Conveyors

A THESIS

PRESENTED BY

HARRY HIMELBLAU

TO THE

PRESIDENT AND FACULTY

OF

ARMOUR INSTITUTE OF TECHNOLOGY

FOR THE DEGREE OF

MECHANICAL ENGINEER

MAY 29, 1919

APPROVED:

ILLINOIS INSTITUTE OF TECHNOLOGY ^A^^ ^ /9

PAUL V GALVIN LIBRARY -^^ ^' /yvi^^z^La,-^^^//^

35 WEST 33RD STREET ^_ P~(«p^fM«:l«nic.UEnainecrin,

CHICAGO. IL 60646 . ^^_J(/ /yiL^Co^

^^ \ Deu^>r Engineering Studies

Dean of Culluial Studies

Digitized by tine Internet Arcliive

in 2009 witli funding from

CARLI: Consortium of Academic and Researcli Libraries in Illinois

http://www.archive.org/details/steamjetashconveOOhime

lABLE OF G01JT£KTS

PAGE

Method of Operation 1

Mozzle Design 5

Plow of Steam in Pounds per Minute through I<Iozzles of Different Diameters at Different Pressures, lable 1 Part I 7

Table I Part II 8

Table I Part III 9

Description of Apparati..s 10

Properties of the Ash 11

Storage Bins IS

Cost of Re-inforoed Concrete i'lat-bottomed Ash Storage Bins Table II 14

v.ater Jet 16

Ash JTusibility 17

iVear liners 20

28421

TABLE Qg QOIITEMTS (Contd.)

P-.GE

Reinforced Extensions 21

Straig'ht Line Steam Units 22

Fuel Cost per IOOO7 Steam

Table III 24

Operating Cost 25

Advantages of Apparatus 31

Disadvantages of Apparatus 33

Description of Illustrations 56

Plate I .Stirling Boiler, 40 u'estinghouse atoker

Plate II Stirling Boiler, 41 B & .V Stoker

Plate III B&W Boiler,

Taylor Stoker 42

Plate IV Heinie xjoiler, 43 Riley Stoxier

Plate V ./ickes Boiler, 44 Murphy stoker

Plate VI, B.&',V. Boiler, 45 Honey Stoker

The practical application for conveying ashes by means of the steam jet, developed recently to a high stage of perfection, may be considered as the latest development in the field of power plant engineering. Po,ver plant owners are just awakening to its adap- tability.

The steam jet ash conveyor is an apparatus for the removal of refuse resulting from the combustion of coal in boiler and special furnaces irom its original point of deposit to a final disposal station. The deposit point refers to the ashpit generally, but in the handling of soot and combustion ash refers to either the back passes of a boiler, breechings, euonomizers, base of the stack, or the back of the mud drum in the dtirling type of boiler. The final point of dispo&J. may be either a bin discharging the refuse into a railroad car, a ^vagon, an automobile

-2- truok or a target "box discharging on an open field.

Primarily the apparatus may be divided into tvvo distinct parts: suction and dischaige lines. The suction line is located so that the intakes may be arranged to allow the ashes to be either mechanically or automatic- ally fed into the system. The ashes may be hoed, shoveled or fed, according to condi- tions at each individual installation.

Ashes are drawn or hoed into the suc- tion intakes when the bottoms of the ashpit doors are located t./o or three feet above the boiler room basement floor. The intake of the suction line is tnen located immed- iately below, usually supported on the floor by footings. The operator merely hoes the ashes through tne door in'oo the intake tee. 'j}h.e~j are removed through the

-3-

pipe as fast as the man can conveniently v;ork vvithout tiring. It a ould be particularly "borne in mind tnat only one intaice may be open at a time, -hen the tee ahead of the one which is bein^ used is opened, there v;ould be a tendency to short-circuit air, thus decreasing the vacuum at the point desired. The operation of this system may be handled easily by one man, inasmuch as but one intake tee is used at a time.

Shoveling ashes into the conveyor pipe is resorted to ,vhen the apparatus is located in a trench below the boiler-room floor. This condition exists in plants having either no basement or v.'hen the fiirnace conditions require the withorawal of the refuse from doors in front of the grates. Hand-fired furnaces or natural draft stokers are general representative types requiring this metxiod of ash /.'ithdra.val.

-4-

Feeding ashes through a gate in a hopper bottom ashpit into the conveyor pipe is a method not so irequeutly used, but gvhen adaptable to conaitions, offers an ideal method of disposal. The design of this method of feeding does not allOA' the ashes to avalanche into the conveyor but considers regxuating the flow, thus injuring that the system .vill v;ork ./ithout clogging. The ashes should discharge from the ho-oper and go into the system at an angle of repose of a .out 45 degrees. The operator can easily prevent clogging oy standing beside the trough and withdrawing tne lar^:er clinkers. These are broken up during periods of non-operation lo^r future feeding into the system.

To insure sufficient vacuum in the suction line the steam nozzle i3 located

-5-

as close to the first intake as convenient. The discixarge part of the apparatus is located beyond the main steam unit and may be considered as carrying the ashes in suspension due to the velocity of the steam ejected from the nozzle. Therefore, dis- crimination is made bet.veen suction ^^nd discharge lines by the fact that in the former ashes are carried in suspension by the vacuum in the conveyor pipe, created by the nozzle ahead, while in the discharge line the ashes are held in sixspension by the pressure exerted behind.

Maximum theoretical pov;er developed by a jet of steam flo..'in.-^ tn:.ough a nozzle is dependent only upon the weight ox steam per unit 01 time and the initial velocity, There- fore the higher the initial pressure (or corres- ponding velocity/ for a given rate of flow, the

greater will be the pOvver developed and the

-6-

higher tae efficiency. I'he maximum velocity at tjie mouth oi the nozzle for a given rate of flo.; is obtained ..hen the expansion to the external pressiire occurs ..'ithin the nozzle. It is of utmost importance that a nozzle be correctly proportioned to convert the pressure into velocity energy. It laay be stated that the velocity ox ihe steam parsing through a correctly proportioned expansion nozzle in- creases from approximately MOO to 2^00 ft. per sec, lor moatxy all operating pressures.

fo obtain maximum velocity the nozzle must converge at the throat by a vvell rounded curve and diverge to the mouth at an angle of approximately 10 degrees. x'he -weight of steam discharged through a nozzle is a fxmction of the diamater and may be deter. ..ined oy ilapier's formula. The initial pressure at the nozzle and the nozzle's diamater must ue kno.vn. Table 1. is based on this formula.

-7-

Table 1 Part 1 Flow of steam in Pounds per minute Through nozzles of different diameters at different pressures

Dia.in Inches

Area Sq. In.

Pressure, Pounds Cauore 60 90 100

1/8

O.OlE

0.995

1.10

1.21.

5/ 16

0.028

2.24

2.48

2.72

1/4

0.049

3.98

4.39

4.81

5/16

0.077

6.25

6.875

7.54

S/8

0.011

8.96

9.92

10.85

7/16

O.lbO

12.21

1;5.49

14.78

1/2

0.19b

15.92

17.61

19.30

9/16

0.249

20.17

2E.3

24.42

5/8

0.307

E4.90

27.55

30.16

11/16

0.571

^0.15

5S.31

56.45

5/4

0.442

55.85

39.6

45.43

15/16

0.518

42.10

46.5

50.90

7/8

0.601

48.75

55.96

59.10

15/16

0.690

56.10

61.9

67.80

1

0.785

65.75

70.4

77.22

Uote: Slide sxvle Calciilations

'i'able 1 Part 11

Flow of steam in Pounds per minute Tlarougii nozzles of different diameters

at difierent pressiires

Dia.in Area Pressure , Pounds Gaup-e

Inches Sg. In. 110 115 125

1/8

0.012

1.51

l.b6

1.4:1

3/16

0.026

2.96

3.07

3.31

1/4

0.04y

5.23

5.44

5.86

5/16

0.077

8.51

9.175

10.75

3/8

0.011

12.28

lb, 2c

15.6

7/16

O.lbO

16.72

18.0

21.22

1/8

0.196

21.82

2b. 5

27.7

9/16

0.249

27.60

29.75

35.1

5/8

0.;;07

34.10

36.7

43.31

11/16

0.&71

41.25

44.4

52.4

3/4

0.442

49.20

52.9

62.3

13/16

0.518

57.64

62.0

73.1

7/8

0.601

66.84

72.0

84.8

15/16

0.690

76.74

82.6

97.5

1

0.785

87.31

93.9

110.82

iJote: Slide Rule Caiouiations

-9-

lable 1 Part 111.

?low o±' steam in Pounds per minute

Through nozzles of different diameters

at diiierent pressiires

Dia.in Area Pressure, Pounds Gauge Inches Sq. In. 150 175 200

1/8

O.OIE

1.73

1.99

2.26

3/15

0.028

3.9

4.49

5.09

1/4

0.049

6.9

7.96

9.02

5/16

0.077

10.75

12.47

14.05

2/8

0.011

15.6

17.95

20.35

7/16

0.150

21.22

24.4b

27.7

1/2

0.196

27.7

51.9

36.13

9/16

0.249

35.1

40.4

45.75

5/8

0.30 V

43.31

49.89

56.5

11/16

0.571

52.4

60.56

68.31

3/4

0.442

62.3

71.83

81.3

13/16

0.518

73.1

84.26

95.45

7/8

O.dOI

84.8

97.77

110.5

15/16

0.D90

97.5

112.24

127.1

1

0.76b

10.82

127.71

14^^.5

Note: Slide ?.ule Calculations

-10- For similar boiler operating conditions the diameter of a nozzle is increased propor- tionally with the decrease in boiler pressure. A boiler plant operating at 200 lb. boiler pressure will require a smaller nozzle for the removal of the ashes than a plant operating at the lower pressure oi 100 lb., aitnoxagh the smaller nozzle of the lormer may use more steam than the lauter.

i)etex-raining the most efficient operating nozzle before an installation is completed is difficult. It is based upon the design of the boiler plant, operating conditions, boiler pressure consistency and moisture content of the ashes and the final disposition of the ashes. I'he design of the Doiler plant deter- mines the location of the riser conveyor pipe. All existing piping, apparatus, roof trusses and contemplated wori: must be taicen into consideration. It is desirable to locate the

-11-

riser convenient to the first intake inasmuch as the main steam unit is usually located at the base, and the proximity of the nozzle to the lirst intake tee generally results in a better vacuum.

Steam is transmitted to the nozzle at as near boiler pressure as possible. This is accomplished by usinf^ a steam line of suffi- cient size, .vith a minimum number tvu-ns, and if possible taken off of the main header. Traps are provided if the boiler pressure is low or condensation is likely to occur, tnereby providing a thoroughly ary steaiTi.

'J?he property of the ash is an important consideration for this type of apparatus. A'et ashes have a greater v/eight per unit volume and are not as capable of suspension as tne drier ash in the high velocity air. there- fore, westing and then introducing tne ashes into the syste.u usually causes a depositing on the bottom of the pipe

-12-

Ashes are generally fed as hot as possible. The steam condensing on the cooler surfaces of the ash "kills" the heat before delivery- is effected. Additional labor and e^tra expense are entailed when it is fo"und necessary to saturate the ashes /;ith water or to keep the ashpits in a wet condii^ion to avoid burning the grates.

Location of ihe final disposal station for the ashes ia determined by the purchaser's conditions. The bin should be located as near to the riser as possible to recLuce the operating power. The horizontal discharge is located in a straight line from the riser to the bin avoiding turns, bends and the resulting scrub oing action that occurs when the direction of flow is changed of high-velocity abrasive

material.

The clearance limitations for bins located over a track is specified by law.

These bins are therefore looated high enough to allow the ashes to be diacxiarged directly into gondolas. i'his necessitates a high vertical riser before it takes the horizon- tal course, oiten projecting tnrougn coal bunker and the roof of the plant, ihe height of the riser is determined by information concerning the ash bin, such as the desired capacity and requirements.

iiins are made of either reinforced concrete or steel. The former construction is generally used, being cheaper and offering more resistance to the corrosive action of the ashes. The bin colimns and flat slabs are poured at the same time, provision being made for openings large enough for the installation of gates of sufficient capaxjity to allow ready removal of the refuse. It may be either cylindrical, rectangular or square with sufficient reinforcing to over-

-14-

come tlie internal pressure oi the confined material. In smo-ller caioacities, it is more economical to plaster concrete on a siarface of expanded metal if of siifficient strength and properly designed.

Table II represents approximately the actual costs for tne material and com- plete erection of reinf jrced-concrete and flat-bottom ash storage bins.

Table II. Cost of Heinf orced-ooncrete

J'lat-jjottomed Ash storage ^ins.

Capacity of bin Internal aize

T 0 i^" S

m jj'eet

Cost

10

8x8x1 E

^1500

20

10x10x16

1800

30

12x12x16

2000

40

13x13x18

2250

50

14x14x19

2450

60

15x15x21

£650

-15-

isins constructed of steel have been iised extensively but it has been iouna ad- visable to line their inner siirfaces v;ith concrete, particularly where the ashes are allowed to aocumulate for a considerable length 01 time. jVhen well constructed with proper riveting, caulking and painting, they satisfactorily resist the corrosive action of the ashes. I'heir general construe tion is with hopper bottoms, supported on latticed steel columns.

The flat bottomed concrete bin is now constructed more extensively than those with the hopper bottoms. j.'he ashes when being discharged are allowed to form their c^ngle 01 repose and flow freely through the gate, thus removing the maximum quantity. The actual slope oi tne bin bottom is away from tne gate, xhe conaensation accumulating witnin the bin is removed t^y properly

-16- located nipples buried in the concrete so

that the discharRing ashes .';-.re comparatively dry and have a free flow. The hopper bottom bin concentrated this moisture at the gate with an arching effect, which prevented a free flow until the wet material had been removed by poking with heavy bars. During the ./inter a collection of moisture at the gate had a tendency to freeze over .requiring considerable waste of live steam ag-ainst this material before it could oe removed. V/hen it is desired to discharge the ashes directly for fixling purposes near the plant, a water jet is installed in the hori- zontal near the end of the discharge pipe to settle the entrained fine material. i'he water control valve snould be located near the operatinp-; steam valve of the ash-hand- ling system. i^he ashes pass ohroufi-h a so screen of atomized water vupor wnicn is

-17- surrounded and settles the finer particles to the coarser ones. It is not considered necessary to satiirate the ashes, but the use of sufficient \A:ater is required to settle the suspended dust.

Coal from different localities is mined with a widely varying ash and sulphur content, difference in ^.t.u. , and particularly a difference in temperature of the ash fusibility. ;/hen the fusing temperature has been exceeded, the refuse turn into a fluid mass clinging tenaciously to the brickwork and the grates upon cooling, xhe properties may be prede- termined by tne individtial lurnace design, of which there are lour general classifica- tions, namely: overfeed natural-draft stokers, underfeed forced-draft stokers, continuous traveling grates and hand-fired furnaces.

-18- From the overfeed natural-draft stoker the refuse is generally medium sized and abrasive, carrying easily in suspension in the conveyor. Ihe rough surface oi the ash is exposed to the high velocity air currents, which assists in clearing the system of the finer particles. j.'he furnace temperatiires in this type of stoker are generally not too high and the larger clinkers being' friable are easily broken before being fed into the

intake .

The forced-draft underfeed type of stoker has an exceedingly high temperature in the combustion chamber. The refuse is always large and extremely abaasive, being fused by both the nigh -ceraperatures and the continual agitation oi the stoker operating mechanism. Stoicers of this type are used in plants of larger capacities, i'he steam jet ash conveyor is not recommendable for

-19- removal of refuse irom stokers ox this type, unless clinker grinders are provided, or sufficient space in the ashpit is allowed to give the men access in breaking up the clinkers before their discharge inoo the system, iviore time is frequently required in breai.ing- up clinkers, under ordinary operating conaitions than is required in the whole operation of aischarging tnem from the Doiler plant ini.o the bins.

xhe traveling grate stOiter deposits its refuse as tne liiu-s pass over uhe rear shaft. Irrespective of the kind of coal, the ashes are generally fine and are easily handled in a conveyor.

Inasmuch as the ashes aeposited by ohe various types of stOiiers are abrasive, and weigh from oO to 50 lb. per cu. ft., it is necessary to make the pipe v/uich is used for Lheir conveyance of heavy and hard v/hite

-20- cast iron. 'I'he pipe is inaae in ±engchs not exoeeain^- 6 ft. iu the 6 ana 8-in. s/atems so that they may be conveniently handled v;ithout oreai'.age. ihe maximum lengths of the d-in. pipe v/eigh 6b0 lo. , each - averag- ing 105 lb. per foot.

As tne ashes are conveyea in the pipe, moving at a hi.^a ve-LOcity and in suspension, it is of utmost importance to provide easily renewable «vear liners here they impact u.t the bends. Specially desi^srned fittings are provided and arrangea in such position tnat the liners may by replaced without discon- necting the bystem. Covers ara advantage- ously placed for the purpose of holding the liners while otner covers are provided for inspection, thus avoiding the possibility of any damage being aone due to .vorn out replaceable parts. I'he liners are con- structed ox a specially hard chilled .vhite

-21-

cast iron and afford the maximum resistance to wear.

Reinforced extensions are used beyond each bend, providing an economical method of replacing sections worn by the ashes. I'he amount oi wear in the system is proportional to the amount of ashes removed and the dis- tance between the disposal point and the ashpits, because of the difference in the velocity of the air necessary for the conveyance of the ash v;ithin the pipe.

I'he efficiency of the steam jet asn convey- or is based on the quantity oi steam used per ton of ashes removed, jhen a small nozzle is used, or when only a low nozzle-pressure is obtainable, the vacuum within the conveyor pipe is correspnndingly low. A slightly larger nozzle, or increased steam pressure, increases the total quantity ox ashes removed. i'he pounds of steam per ton of ashes required

-22- becomes a minimtim v/hen a man feeds the asJies to tne intake at normal speed.

In long suction lines tne nozzle located at the base of the riser creates insufficient vacuum at the intakes located at the farther end of the line. ihis vacuum loss is due to the frictional resistance offered by the walls of the pipe to the high velocity air currents. The straight line steam unit or booster, has been found to be a practical remedy. This fit- ting is generally located midway between the riser and the farther end of the suction line, spaced about 50 it. from the main steam ;init. The booster has two tiozzles of a size large enough to create sufficient vacuum in the suction line behind. The use of the small noz2;les in the booster allow for a smaller nozzle at tne base of the riser than woula be other;;ise required. This effects a mini- mtmi maintenance and a more satisfactory

-£3-

operation of the system, and is recommendable , althoijgh it would seem that one larsier rather than three smaller nozzles would be more efficient.

There are instances where this type of ash conveyor has not conformed to plant con- ditions. These cases generally are in boiler plants where an exceedingly large v^uantity of coal is consumed or a low pressure is main- tained. This equipment has oeen round vo De adaptable to nearly all manufacturing and steam generating plants. To keep down the time element ana the maintenance, limitations for any one system have been restricted to approximately 50 tons of ashes removed in 24 hours. In the larger stations it is advisable to install more than one system, each properly arranged to receive its per- centeere of the ashes.

-24- HAijLE III. -FUaL GOS'J 2m 1000 LB. OF STEAM

COST QJj' COAL PJSR TQH

Li3. STKAIvI PER LB.

GOAL $2.00 -jig. 50 $2.00 4'6,50 ^4.00

4 0.250 0.:d12 0.S76 U.4S8 0.500

5 0.200 0.250 O.ijOO 0.350 0.400

6 0.166 0.206 0.250 0.292 0.&S4

7 0.142 0.178 0.214 0.250 0.284

8 0.126 0.156 0.186 0.218 0.250

9 O.llS 0.142 0.170 0.196 0.E22

$4.50 $5.00 J5.50 j6.00

4 0.562 0.625 0.687 0.750

5 0.450 0.500 0.550 0.600

6 0.375 0.417 0.458 0.500

7 O.o21 0.O57 0.393 0.429

8 0.281 0.312 0.344 0.575

9 0.250 0.284 0.312 0.340

-25-

Examples of successful systems repre- sentative of operating costs are cited as follov;s:

1. Prom the LaSalle Hotel, Chicago, Illinois, vValter Bird, Chief Engineer, volunteers the folio/zing information per- taining- to his plant: Six- inch steam jet conveyor purchased in 1913 at an initial cost of v57£.00. ihe average coal con- sumption is 42 tons per day and analyses show 12> refuse. xhe time required to remove the daily average auantity 4.8 tons of ashes is 1-1/2 hours. One 5/8 in. nozzle is used, operating at 150 lb. boiler pressure. Referring to I'able I, 45. 3 lb. of steam per min. is discharged from the nozzle. In 90 minutes, the steam consump- tion is 3897 lb., wnich reduces to 812 lb. per ton of ash. At the present writing (March 10, 1919;, the cost ox ohe steam in

-26- this plant is b5ji{ per 1000 ID., so that the steam cost per ton of ashes removed is 28.4^.

I'he average maintenance per year equals $50.00, averaging 2.88)6 per ton of ash. Interest at 6^/o on ^572. 00 amounts to ^24. 52 or 2)6 per ton of ash. I'hus the oi3 rating cost per ton exclusive of labor is ^S.28^. One man is retained exclusively for the re- moval of ashes, at a salary of ^75.00 per month. ;Vhen not actually operating the system his duties consist in the removal of ashes from the hin into industrial cars, which are hauled through the subway; cleaning of ashpits and miscellaneous boiler room duties. The above salary reduces to 52^ per ton of bsh handled. Only 20^o of this in amount ^10.40 should be charged directly against operation of the system and the balance to incidental boiler room expense. Adding the direct laoor charge increases

-27-

the cost per ton ash handled to 45.68)^.

l»Ir. Bird states that the cost of the ash removal previous to the installation of this system was considerably higher than the contained figures, ne is per- fectly satisfied //iih the results and feels that the plant could not gei along satis- f.;otorily without it, as this particular type of apparatus conforms to the conaitions at the hotel.

2. A large power station desires to remove part of its ashes through a steam Jet ash conveyor, v/ith the intention oi building a 60-ton concrete bin on a pile trestle par- alleling the hanks of a river. I'he original investment of vlO,000 is to include a steam jet ash conveyor, a 60-ton concrete bin, piling for the concrete bin, repairs or re- building of dock fill, etc.

fhe boilers served w'ill produce aoout

-28- 15 to 18 tons of ashes per day or a total of 6570 tons per year. Xhe boiler pressiare equal 125 lb. per square inch ana the noz- zle press-ure 115 lb. per square inch. The nozzles used are one 11/16-in. at the case of the riser and two 5/16-in. at the boos- ter. The latter is used one -half of the time required for the total operation of the system, so tjiat from I^apier's formula the average steam used equals 50 lb. per minute, or 3000 lb. per hour. The system will remove 6 tons of ashes per hour and will require 500 lb. of steam per ton of ash removed. The cost per ton of ash may be sxjmmarized:

Steam, 500 lb. at SOc per 10001b. .-JO.15 Labor, o4 for 8hr. & 6 tonspgrhr. 0.08

interest on investment, 6yo 0.09

iiaintenance 0.03

Depreciation 0.02

Total cost per ton 0.37

-29- 3, It has been decided experimentally that a system wnich has a suction line not longer than 60 ft., a riser of 50 ft., or less and a horizontal discharge of 50 ft., and boiler pressiire of 150 lb. per sq. in. will remove approximately six tons of ashes per hour, using a 5/8 in. nozzle at the base of the riser. I'his juantity is determined by a speed suiiicient to conveniently keep the ashes in motion, without the probability of overloading the system. A steam consumption of 4o.b lb. per minute would be reuuired, or 455 lb. per ton of ashes removed.

./ith steam cosoing 50c per 1000 lb. ,tne steam charge per ton of ash would be 15^. I'he charge for maintenance should not exceed 2-1/2^ per ton. Labor charsred a-;ainst actual operation oi the system v/ould be 8-1/5^ per ton, based on a ^va=?e of j* Per 8-nour day.

-so-

4. In the new I'J or thwe stern Elevator at South Chicago, operated by the Armour urain Co., two systems have deen installed, one under each row of boilers. xhey nave been in operation since karch 1918. I'he boilers are oi" the t>ti,rling type operating at £00 lb,

pressure and 150^ superheat^ equipped with A^estinghouse forced-draft imderfeed stokers. The average coal consumption is 56 tons per 24 hours. The quantity Oi ash removal per day amounts to 8.4 tons, on a lo}o basis. Its removal requires the use of steam for a total of three hours in both systems, i'he cost 01 coal is 94.50 per ton at the bunker and the highest evaporation is 9 lb. of waoer per pound of coal. ihe fuel cost oer 1000 Ih 01 steam would be 25^. One 1/2-in. nozzle at 200 lb. pressure uses 56.1^ lb. of steaia per minute. Per ton of ash the steam requirement

would then be 774 lb., and the steam fuel

-31- oost 19.i55^. i'here have been no maintenance charges since the installation has oeen in operation. xhe time ol one man is exclusive- ly required to remove the -ashes.

ADYjilUAG-ciS Q.J' I'H-a ^'H^^Ml J HIT ASh UOKV-c^YQR Labor saving - I'his apparatus eliminates considerable labor, as its operation requires the service oi out one man. ihe v;heelbarrow method is eliminated. There has been too much interxerence between firemen and ash men in most plants, xhe method of wheeling out and discharging the ashes upon the ground near the boiler room has been lound unsatis- factory. Adaitionai labor is also required in the shoveling oi the ashes from the ground on to wagons or trucks.

Difference of i:.levation - ,,here there is a difference of elevation oetvveen the boiler room floor and the disposal point the asnes are handled in one operation. Office build-

-32- ings and industrial plants necessitating the elevation o± the ashes have given this point consideration.

Use of Steam. - i'he steam could be re- stricted to periods of light loads or sudaen throwing oif of heavy loads, th^-t is, noon and evening, in a manufacturing plant. j.he load curve would determine the convenient time. It is considered more economical to utilize the steam at these periods than to allow its escape to the atmosphere through safety valves.

Railroad Gar jjiscnarge. - ,«hen it is essential to discharge ashes into a rail- road car because of the lack of ash storage facilities, the soeam jet ash conveyor is an economical type of apparatus to employ. The removal from the bin into the cars is generally easily accomplished. ±he time for fill in.;; a car varies from 15 to 60

-25- minutes, aocordin.^ to the condition of the ash and the temperatxire of the outside at- mosphere.

DISAJVAIUAGES Oj' x'H^ Sl'^iUvI JET ASh QQIiVjJjfOR

Utilization oi' Live ateam. - The opera- tion of the system depends fundamentally on the expandability oi live steam directly from the hollers. Inasmuch as the steam is diSGharv5:ed into the atmosphere it is wasted and should he charged against the operation of the system.

High Pressures Required. - A boiler pressure oi over 7b lb. per s>.i. in. muso be continually maintained xor economical oper- ation. It has been found that heatin-? plants operating on a pressure less than stuted require an exceedingly large noz^ile, and inasmuch as tnere is considerable condensa- tion in a plant oi tnis cnaracter, the

-34- results obtained nave been unsatisfaotory.

Noi:zi.e DiariBter Must be L;orrect. - A boiler plant operating with a variable boiler pressure in either direction means either a waste of steam due to increased capacity or slugishness of operation snould the boiler pressxire drop. The nozzles as installed by the engineer are correct only for a constant Doiler pressure, and conform to the conditions at the time tney are in- stalled, ihe nozzle is located in the main steam unit and is not readily interchange- able.

Dryness of Ashpit and Ashes. - The boiler room operator musx keep his ashpit ana ashes absolutely dry to secure effic- ient ana economical ash removal.

Time Required. - Large abrasive clinicers must be broken Dei ore tney can be conveyed into the system, m the operation oi the

-35- larger boiler plants considerable preliminary work is required to break the ashes and put them into condition for removal through the system. j.he fine ashes, dust, soot, etc., cannot be conveyed in tne same system aesign- ed for larger clinkers, Du^ reuuire a special 3 to 4-in. low-capacity system.

interruptions due to Plugging. - rlxigging of the system frequently occurs, attributed frequently to two clinkers wedging together. Live steam is alv;ays required in the removal 01 ashes when plugged, as there is no way of picking up the vacuum unless the system is in operation when the plug is being removed.

-26-

The following illustrations indicate representative and recorarnendable installations of the suction line for tne removal oi reiase from the ash pits.

PLATE I.

This installation of Stirling Boiler and ,/estinghouse foroed-draft underfeed stoker actually exists at zhe iJorth;/estern elevator, South Jhica.2:o, Illinois, operated by the Armour Grain Company.

The clinker ic; discharged ay the dumping mechanism of xhe stOKer, In the c^sn hopper two large slide gates are proviaea, allowing the refuse to drop to the tray. J.'he operator stands immediately in front of the system and hoes the ashes into the suction pipe.

The soot conveyor is proviaed for the removal of comuuai.ion ash and soot accumulated and blo\vn from the tubes ana mua drum.

-37-

PLATE II A typical representation ox a chain grate stoker and Stirling Boiler, xhe position oi the ash conveyor can be located in either locati-.n as sho-Mi in accordance .;itn the quantity aesired for removal. -he soot con- veyor has been used in actual practice ana found particularly adaptable for this type of DOiler.

l^Lkm III A B & iV cross-baffled boiler and forced- araft unaerfeed stoker is represented, 'fhe operati.n oi the asn conveyor io very con- venient, as considerable of the refuse will avalancne into uhe system when the ash pit uoor is opened, xhe soot oonveyor is par- ticularly aavantaseously located. xhis type Ox installation it: entirely self-cleaning from both an asn ana aoot atanapoint.

-28- PLATE IV This illiistration oifers a su.?£?estion for flexibility in ash, soot ana silting conveyance. j.nasiauch as a Kiley otoicer silts to some extent, the sittings are aliov;ed to accumulate and may be aiscnarged airectly into me coal buniiers above.

PLAi'S V

ihe labor saved through the installa- tions 01 ash uonveyors in connection with the Murphy type oi stoicer has proven re- markable in nearly all instances. xhe cliniier .-grinder allo,;s the refuse to dis- charge into tne asn pit in quantities of suitable size to oe readily removed through the ■bysteni.

-39- PLAia VI

The ash conveying system in connection with a .'.oney otolcer is noL alvvays profitable "because oi the lar;^e quantity oi siftings mi— ing with the ashes ana being irequently discharged through the apparatus. Hov/ever, this stoker has not been on tne market re- cently and one steam jet asn conveyor is only considered in one oooicers opex-ating for some time.

j.he soot convenor proposal indicates that the uoiier .voula be entirely self- cleaning should a soot blov/er oe installed.

Plate I

Plate II

Plate III

arTiNGs

CONVEYOf=l

Plate IV

^^^^^1=^^^^^^

nmrnlirnrnr lijz.

Plate VI