Патент USA US2137856код для вставки
NOV. `22, Q. D, RICE ` 2,137,856 FURNACE >Filed Dec. 17, 1937 ll-NIVENTOR Orl/12H61?. ,Rice , ¿M Patented Nov. 22, 1938 ,y s ` ` p , . „ »UNITED N STATES PATENT OFFICE ` FURNACE n Orville D. Rice, Pittsburgh, Pa., assigner to Rust ‘ Furnace Company,v1’ittsburgh,_ Pa., a corpora- ` l ¿tion of Delaware ‘Application December 17, 1937,»seria1 No. 180,336 zcxaims. (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. 10 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. 20 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 proper. . ` 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 , i The amount of waste gases diverted and recir- 55 2,187,856 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 16 llses. » ’ 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. 20 invention or scope of the appended claims. ORVILLE D. RICE.