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Full text of "The Flow Of Gases In Furnaces"

202

APPENDIX VII

I

3600 (11.8 ft.)

It is well known that when patching bottom it is necessary
to keep the doors closed as much as possible in order to avoid
chills, which are likely to develop into cracks and leaks in the
bottom. Many beautiful octahedral steel crystals have been
discovered in tearing out old furnace bottoms.

When the pressure in the furnace gets higher than the atmos-
phere a sharp sting of
flame is developed and
fuel must be burned
to maintain it. Some
m e 11 e r s and many
heaters keep the doors
of their furnaces deco-
rated with a halo of
flame. In some cases
it is necessary to main-
tain this sting owing to
the defective design of

3200 (10.50 ft.)           I                            , 1         /.                         rni

the furnace. There is
no question whatever
that this method of
working will prevent
cold air being drawn
into the furnace. It is
te easiest way "; the
company pays for the
excess fuel, and the
melter or heater has plenty of time to sit down and "watch
'er burn." In foreign plants the technical control of the furnaces
is more closely maintained than in this country because fuel is
expensive.

In order to sinter the bottom of the furnace in place it is
necessary to direct the jet of flame so that it will lick the hearth.
In order to do this the air and gas ports must be given a suitable
inclination toward the hearth and the velocity of the flame must
be sufficient to carry it down to the bottom. The velocity which
will be impressed upon the jet of air entering the furnace will be
fixed by the height from the bottom of the regenerators to the port
and by the area of the port and the flues leading to it. In the case
of the gas a slightly greater head is available as it enters the

Scrap Process
/^///////////^
FIG. 142.—Sections Showing Profile of Hearth
Slope According to Professor Groume-
Grjimailo.