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Патент USA US2137856

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NOV. `22,
` 2,137,856
>Filed Dec. 17, 1937
Orl/12H61?. ,Rice ,
Patented Nov. 22, 1938
n Orville D. Rice, Pittsburgh, Pa., assigner to Rust
‘ Furnace Company,v1’ittsburgh,_ Pa., a corpora- `
¿tion of Delaware
‘Application December 17, 1937,»seria1 No. 180,336
(o1. ess-_15)
This invention relates to a furnace, in particular to a furnace of the so-called regenerative
type in which fuel is supplied from one side and
combustion` products taken off at the other side
during one period, and the direction of firing re:il versed during a succeeding period. The invention will furthermore be described herein with
reference to a soaking pit furnace although it
may be applied as well to furnaces of other types.
It has long been realized that in the operation
pf regenerative soaking pit furnaces, fuel of low
caloriiic value has an advantage in that it is less
`likely to cause washing or melting of the ingot
surfaces than is fuel of higher thermal content
15 because such washing or melting introduces the
necessity of chipping surfaces `of the ingots to
remove these defects. On this account `blast
furnace gas has been widely used for firing soaking pit furnaces.
I have invented a furnace and method of operating the same which secures the advantage of
fuel having a low heat content in furnaces fired
with fuel having a relatively high heat content.
In accordance with my invention, I divert a
25 portion` of the combustion gases flowing from
the furnace toward the stack and return them
tothe side of the furnace on which fuel is being
supplied. ‘ After passing through the regenerator
on the side with the air supplied for combustion,
30 the air and combustion gases are mixed `with the
fuel and combustion occurs in Ithe soaking pit
A present preferred embodiment and practice
of the invention is illustrated in the accompany35 ing drawing and a complete understanding thereof may be gained from the following detailed
description. `In the drawing:
The single figure is a diagrammatic view illus‘ trating a regenerative soaking pit furnace and
40 the connections therefrom to fuel and air supply
means and to a stack for discharging waste gases.
Referring in detail to the drawing, a regener-
ative soaking pit furnace I0 comprises a pit
proper, indicated at II, and regenerators I2 and
4,5 I3. Fuel supply ports I4 are disposed between
the regenerators and .the pit proper and are
connected by suitable piping indicated generally
at I5, to a convenient source of fuel. The fuel
supply to the ports I4 is controlled by a regulating
50 valve I6 and‘reversing' valves I1 and I8.
Air for combustion is supplied to the regener
ator opposite that which is connected to the flue,
by a blower 25 through piping 26 communicating
with the flues I9 and 20. A regulating valve 2l
and reversing valves 28 and 29 control the supply DI
of air to the regenerators. .A diversion flue 30
extends from the flues I9 and 20 adjacent the
point where they join to an interconnecting flue
3|, extending between flues I9 and 20. A blower
32 is disposed in flue 30 and is effective to draw 10
Waste gases from the ilues I9 and 20 and divert
them to the interconnecting flue 3|. Reversing
valves 33 and 34 are located in the flue 3|, making
it possible to direct the diverted waste gases to~
Ward the regenerator on the side of the furnace 15
at which fuel is being delivered.
With the various control and reversing valves
in the positions indicated, fuel is supplied to the
ports I4 between the regenerator |3’and the pit
I I. At the same time, air is delivered by blower 20
25 through valves 21 and 29 and the flue 20 to
the regenerator I3. The air is heated by passing
through the regenerator and, as it mixes with the
fuel supply through the ports I4, combustion
occurs in the pit II. Combustion gases flow 25
through the regenerator I2, the flues I9 and 2|
to the stack 22, since the valve 23 is open and
the valve 24 closed.
As indicated by the arrows 35, `a. portion of the
waste gases flowing toward the stack 22 is diverted 30
through the flue 30 by the blower 32 and delivered
through the flue 3| to the flue 20, since the valve
33 is closed and the valve 34 is open. In this
manner, the diverted portion of the waste gases
is mixed with the air entering the regenerator I3 35
and ultimately with the fuel delivered through
the ports I4. Both the air supplied by the blower`
25 and the diverted portion of the waste gas sup
plied by the blower 32 are preheated to a temperaintimately with the air and waste gases before .
entering the pit. By this method I obtain high
thermal efficiency and still preserve the desired
temperature of the gases in the pit. The inven- 45
tion also makes it possible to maintain a large
volume of gas flow through the furnace, which
is desirable.
When the direction of firing the furnace is to
be reversed, the valve IB is closed and the valve 50
` ` `?'lues I9 and 20 extend from the regenerators
Il is opened.
I2 and I3`to a stack flue 2| communicating with
the stack indicated at 22. Reversing valves 23
and 24, 28 and 29, 33 and 34 are reversed. The
same result as that already described ensues, ex
and 24 in the flues I9 and 20 permit either regen-
cept in the reverse direction.
55 erator to be connected to the stack 22.
ture of approximately 2000° F. The fuel is ad- 40
mitted in finely divided streams, so that it mixes
The relative positions of valves 23
The amount of waste gases diverted and recir- 55
culated through the furnace is preferably varied
in accordance with the condition of the ingots
being heated. This may be accomplished by
suitable control valves or by varying the speed of
the blower 32. When heating cold ingots, little
or no waste gas need be recirculated since the
danger of melting or washing is slight. As the
temperature of the steel rises, the quantity of
waste gases diverted from the stack for recircula
10 tion is increased.
'I'his method of operation pro
vides relatively quick heating in the earlier stages
when the rate of temperatures is rapid, dropping
olf as the temperature increases because of the
recirculation o! increased quantities of waste
Although I- have illustrated and described but
I claim:
1. In a furnace, a combustion chamber, a re
generator on each side of said chamber, means
for supplying fuel selectively to either side of said
chamber, iiues having one end connected to
gether and the other extending to said regener
ators and adapted to serve alternately as `air
supply and waste-gas passages, means for se
lectively supplying air to said iiues and means
eii’ective to divert waste gases from the connected 10
ends-of said flues to points intermediate the ends.
2. In a furnace, a combustion chamber, regen
=erators on each side thereof, fiues leading from
said regenerators to a common discharge point,
means for supplying fuel and air selectively to 15
either side of said chamber, reversing valves in
said flues between said point and said regener
a preferred embodiment and'practice of the in-`
vention, it will be understood that changes in ators, and by-passing ñues extending from said
the construction and procedure disclosed may be point to points in said »mst-mentioned flues inter
20 made without departing from the spirit of the mediate said valves and said regenerators.
invention or scope of the appended claims.
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