US2499926A - Continuous circular ingot-heating furnace - Google Patents

Description

March 7, 1950 D. w. LLOYD 2,499,926

CONTINUOUS CIRCULAR INGOT-HEATING FURNACE Filed April 22, 1947 INVHVTOR.

Donald W. Lloyd a; n BY m, Z W F Patented 7, 1950 UNITED STATES PATENT OFFICE CONTINUOUS CIRCULAR INGOT-HEATING FURNACE Donald W. Lloyd, Youngstown, Ohio Application April 22, 1947, Serial No. 743,034

1 Claim. (Cl. 263-7) This invention relates to the heating of ingots preparatory to rolling in a blooming mill and, in particular, to a furnace including a circular chamber with spaced entrance and exit ends and a circular hearth traveling therethrough.

The heating of ingots in the customary pit furnaces with removable covers is attended with numerous objections. The operators are subjected to bad working conditions. There is danger of injur to the furnace walls in charging and drawing ingots. It is difficult to insure that all ingots will be heated to the same temperature and this causes trouble in the rolling. Considerable heat is lost as well as atmosphere control while the cover is removed for charging and drawing.

I have invented a novel type of ingot-heating furnace which overcomes the above objections and permits ingots to be heated easily and efficiently to uniform temperature, thereby facilitating the rolling. In a preferred embodiment and practice, I provide-a circular furnace chamber shaped in plan having spaced exit and entrance endsand a circular hearth mounted for traveling movement therethrough. I load ingots onto the hearth adjacent the entrance end after preparing a surface or bottom on the hearth to receive them. The chamber has burners whereby the ingots traveling therethrough are heated to the proper temperature. As the ingots approach the exit ends of the furnace, I remove them from the hearth by an unloading crane operating through a drawing opening in the outer side wall of the, chamber. After emerging from the exit end, the hearth traverses the clear space between it and the entrance end, affording anopportunity for.

again making bottom on the hearth preparatory to charging further ingots thereon. The operations of loading and drawing ingot and making bottom proceed continuously, each section on the hearth traversing the successive stages mentioned above.

A complete understanding of the invention may be obtained from the following detailed description and explanation which refer to the accompanying drawings illustrating a present preferred embodiment. In the drawings,

Figure 1 is a horizontal section through my improved ingot-heating furnace taken on a plane just below the furnace roof; and

Figure 2 is a partial transverse section taken along the plane of line II-I[ of Figure 1.

Referring in detail to the drawings, a furnace according to m invention comprises a circular chamber l0 C-shaped in plan having an entrance end ll and an. exit end l2 which are spaced apart circumferentially. The chamber comprises inner and outer side walls It and I4 and a roof l5. Doors l6 and I! are provided for the entrance and exit ends of the chamber. A circular hearth i8 is mounted for traveling movement through the furnace. The hearth may conveniently be compgged of segmental wheeled cars I911, lab, I90, e

Each car comprises a frame 20 having a refractory layer 2! thereon and provided with wheels 22 adapted to travel on rails 23. The rails are carried on girders resting on a foundation F. The sides of the cars have sealing flanges 24 depending into channels 25 mounted on the sides of the foundation containing granular sealing material such as sand.

The refractory layer 2| is adapted to receive a layer of coke breeze or the like in which ingots 26 may be bottomed when the cars are loaded. As shown in Figure 1, the number and circumferential length of the cars is such that, together, they constitute a continuous circular hearth. The hearth may be advanced through the furnace by an convenient means such as a circular rack 21 composed of segments mounted on the bottom of the cars, and a pinion 28 meshing therewith. The pinion is mounted on a shaft journaled in suitable bearings below the hearth and driven by a motor 29 through a reducer 30.

The side walls It and H of the chamber have burner ports 3| therein adjacent the roof l5. Tuyere blocks 32 are mounted adjacent the .ports 3|. Fuel-supply pipes 33 extend to the blocks from manifolds 34 connected to any suitable source of fuel. Hot air for combustion is supplied to the pipes 33 from headers 35 connected to recuperator units 36 constructed adjacent the outer side wall ll-and extending substantially continuously around the furnace. Each recuperator unit has a connection 31 to a source of air under pressure and bailles 38 defining a back-and forth passage for the entering air whereby it makes several passes across heat-exchange pipes 39 disposed vertically in the recuperator. These pipes convey waste gases from an annular chamber 40 in the top of the recuperator to flues 4| in the bottom thereof which communicate with stacks 42. Outlet ports 43 spaced clrcumferentially of the outer wall of the furnace near'the hearth permit the combustion gases to flow-from the furnace after passing around the ingots on the hearth into the chamber 40. Cross connections 44 extending over the top of the furnace conduct hot air from the inner side wall. The headers'35a are con- 3 nected to fuel-B11991! n nes Ila supplying the tuyere blocks 82 on the inner side wall.

The outer side wall ll of the furnace is provided with a drawing opening ll adjacent the exitendofthefurnace. Adoorflnormally clomtheopening. Anunloadingeranellhas an extensible arm 4! adapted to reach through theopenin'gll whenthedoor ll'hasbeenopened toselzeaningotonthecarinalignmenttherewith. The crane ll delivers heated ingots to an ingot tilter located adjacent a blooming-mill approach table II.

In the operation of the apparatus described above for heating ingots preparatory to rolling, I are the burners composed of the ports SI and blocks 32 until the interior of the, furnace OX1 hibits a suitable temperature gradient for heating ingots. The firing of the burners is preferably so controlled as to produce a gradual preheating of the ingots as they enter the furnace followed by further heating to the maximum desired temperature after which the ingots are permitted to soak" at that temperature for a substantial period to insure uniform temperature conditions throughout before they are removed by the crane "I. Ingots to be heated may be brought to the furnace by any convenient means, for example, on buggies traversing an ingot unloading track T. The ingots may be transferred from the buggies to the cars "a, etc., by an overhead crane. The cars are preferably advanced step-by-step through the furnace to facilitate the loading and drawing of ingots. The rate of travel of the cars through the furnace is correlated, of course, to the rate at which the burners are fired to insure the desired heating of the ingots in the preheating, final heating and soaking zones outlined above. I prefer to load ingots on the forward half of the car He, for example, and then advance the entire circle by half a car length, after opening the door It. During the loading of the forward half of the car [9a, the heated ingots on the forward half of car 19d are removed through the opening 45 by the crane 41, the door 48 being opened for this purpose. The door it is then closed and ingots are loaded on the rear half of the car Ila while ingots are being removed from the rear half of the car l9d.

While cold ingots are being loaded onto the car No and heated ingots removed from car [9d, I clean the coke breeze on the cars Nb and 190 by removing any cinder or ash which may have accumulated thereon and level the surface of the coke-breeze layer to place it in condition for receiving additional ingots to be heated. The

arcuate distance between the exit end and the entrance end of the furnace is such, taking into consideration the rate of advance of the hearth, as to permit this operation of making bottom to be carried out effectively. Instead of loading only one-half of a car length between successive advancing movements of the hearth, I may vary the length of the cars or the number of ingots charged thereon and advance the hearth a full car length at each step. The door I1 is preferably kept closed, i. sp nd y sl htly coke-breeze layer on It will be apparent from the foregoing my invention is characterised by important advantages over prior ingot-heating furnaces; In the first place, the adverse working conditions characterizingtheiatterarealmostentirelyobviated. In the second place, the furnace of my invention requires fewer operators than conventional pit furnaces. Since the ingots are charged onto the portion of the hearth which is outside the furnace chamber, there is no danger of injury to the walls during the charging operation. So far as concerns the drawing of the heated ingots, injury to the walls may be avoided by making the drawing opening 45 sufnciently wide and deep. By heating all the ingots progressively through the same cycle of temperature rise, they may be brought to a much more nearly uniform flnal temperature than can be obtained with a pit furnace in which each individual ingot is subject to variations of time and temperature conditions of its exact location in the furnace. This avoids difiiculties in rolling ingots by reason of variations in their temperature. Since the door at the entrance end of the furnace is open only when the hearth is being advanced, loss of heat therefrom is reduced to a minimum. The door for the drawing opening may be closed, if desired, after each ingot is drawn to prevent loss of heat therefrom.

Although I have illustrated and described but a preferred embodiment of the invention, it will be recognized that changes in the construction disclosed may be made without departing from the spirit of the invention or the scope of the appended claim.

I claim:

A furnace comprising a circular heating chamber c-shaped in plan, said chamber having inner and outer walls and a roof, the entrance and exit ends of the chamber being spaced apart circumferentially leaving a clear loading space therebetween, a circular hearth mounted for traveling movement through said chamber, a recuperator C-shaped in plan extending around the furnace adjacent said outer wall, said inner and outer walls having burner ports spaced circumferentially thereof adjacent the roof, and cross connections extending over the roof for conveying heated air from the recuperator to the burner ports in the inner side wall.

I DONALD W. LLOYD.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,362,296 Hagan et al Dec. 14, 1920 1,531,039 Steenstrup Mar. 24, 1925 1,688,393 Manker Oct. 23, 1928 1,914,716 Heuer June 20, 1933 2,074,662 McLay Mar. 23, 1937

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