US2171777A

US2171777A - Annealing furnace

Info

Publication number: US2171777A
Application number: US237423A
Authority: US
Inventors: James C Woodson
Original assignee: LEE WILSON SALES CORP
Current assignee: LEE WILSON SALES Corp
Priority date: 1938-10-28
Filing date: 1938-10-28
Publication date: 1939-09-05
Anticipated expiration: 1956-09-05

Description

Sept. 5, 1939.

J. C. WOODSON ANNEALING FURNACE 1938 3 Sheets-Sheet 1 Filed Oct. 28,

I l I I I ,1 1/ 1 INVENTOR (James C. Woodson Sept. 5, 1939. J. c. WQODSON 2,171,777

ANNEALING FURNACE Filed 0d. 28, 19:58 3,Sheets-Sheet s LEINVENTOR I JamesCZWoooson Patented Sept. 5, 1939 UNITED STATES 2.171.777 ANNEALING FURNACE James C. Woodson, Cleveland, Ohio, assignor to Lee Wilson Sales Corporation, Cleveland, Ohio,

a corporation of Ohio Application October 28,

4 Claims.

This invention relates to a furnace and, in particular, to a furnace adapted for the metallurgical processing of material such as ferrous sheets or strip. Specifically, the invention. concerns a furnace adapted to receive a pair of spaced stacks of sheets or rows of coils and provided with means for supplying heat to opposite sides of such stacks or coils. This is in part a continuation of my copending application Ser. No. 166,052.

Furnaces of the cover type have gone into wide use in recent years and in everyday operation, have served their intended purpose very satisfactorily. Special problems have arisen in certain cases, however, and it is anobject of this invention to provide a solution for one such problem, viz., the annealing of sheets having a length several times (four to six' times) their .width.

I have invented a novel furnace particularly adapted .for annealing long narrow sheets, which I has a lower cost per ton of monthly capacity than furnaces siuch as those used heretofore and operates at an efliciency equal to or greater than that of the latter. In-a preferred form of the invention I provide a furnace, preferably though not necessarily of the cover type, with charge supports adapted ,to receive spaced stacks of long narrow sheets and having heating means on the side walls of the furnace and at the central plane therethrough whereby each stack is heated from both sides thereof. The details of the invention will be explained in the course of the following description of the preferred,embodiment above mentioned which is illustrated in the accompanying drawings. In the drawings:

Fig. 1 is a transverse section through a furnace in accordance with the invention;

Fig, 2 is a longitudinal section taken substantially along the plane of line II--II of Fig. 1; line I -I of Fig. 2 indicates the plane on which the section shown in-Fig. 1 is taken;

Fig. 3 is a partial sectional view taken the plane of line IIIIII of Fig. 2;

Fig. 4 is a sectional view taken along the plane of line IV-IV of Fig. 3;

Fig. 5 is a diagram illustrating the fuel supply system for the heating means of the furnace; and

Fig. 6 is a diagram illustrating the arrangement of certain parts of the furnace.

along 50 for the present, to Figs. 1 and 2, the preferred embodiment of my furnace comprises a base It having a heating cover I I liftably disposed thereon. The base It] includesa refractory layer or hearth 12 built up on a supporting frame come 55 prising structural members l3 and a base plate the ends of the latter.

Referring now in detail. to the drawings and.

1938, Serial No. 231,422

M. The hearth l2 includes spaced piers I5 and a curb l6 extending therearound. Charge supports ll are disposed on each of the piers IS, the arrangement of the supports on each pier-beingshown diagrammatically in Fig. 6. Bottomplates l8 rest on the supports l1 and are adapted to receive and support a charge such as a stack of sheets IS.

The hearth I2 is provided with a layer of sealing material 20 such as sand disposed within the curb IS.- A protective cover 2| is disposed over each of the stacks I9 with its lower edges penetrating the layer of sealing material. A sealing channel 22 extends around the base H] for cooperation with a sealing flange 23 depending from the heating cover H.

The heating cover H comprises an open-bottomed enclosure including side walls 24, end walls 25, and a roof 26 assembled within a frame including buckstays 21, beams 28, and sheathing plates 29. The inner surfaces of the walls and roof of the cover, like the hearth I2 on the base ID, are composed of refractory material.

Heating tubes 30 are mounted on the side walls 24, being disposed in spaced relation therealong. Suitable openings 3 I are formed in the side walls to receive the ends of the tubes. The upper ends of the tubes pass through a sealing box 32 filled with granular material such as sand, on emerging from the furnace walls. Each tube has a burner 33 projecting'into' the lower end thereof and adapted to be supplied with fuel from one of a pair of

manifolds

34 and 35. Alternate burners are connected to the same manifold, adjacent burners being connected to different manifolds as shown diagrammaticallyin Fig. 5. Spark gap igniters 36 are mounted on the upper ends of the tubes 30 and are connected to transformers 31. Exhaust ducts 3 8 extend along each of the side walls and have openings 39 into which the upper ends of the tubes 3|) extend. Stacks 40 extend upwardly from the ducts at points intermediate A bank of heating tubes indicated generally at 4| extends inwardly through each of the end walls 25 substantially alongthe central, longitudinal, vertical plane through the furnace. Each of the banks 4| includes heating tubes 42 graduated in size, the largest tubes being disposed adjacent the bottom and the smallest tubes I adjacent the top of the bank. The outer ends of the tubes pass through a sealing box 43 filled with granular material such as sand and are provided with'burners 44. The inner ends of the tubes enter sleeves 45 extending from vertical exhaust ducts or headers 46 at right angles thereto. As best shown in Figs. 3 and 4, each of the tubes 42 has spacer fins 4'! secured thereto as by welding, which position the ends of the tubes rela tive to the sleeves 45. The fins are not secured to the sleeves however, and thus fioatingly support the inner ends of the tubes for free movement in the sleeves 45 on expansion and contraction of the tubes. Fuel is supplied to the burners 44 as indicated in Fig. by manifolds 48.

A hanger 49 depending from the roof 26 is provided for supporting each bank of tubes. The exhaust ducts 46 have transverse pins 59 extending therethrough adapted to engage notches formed in beams 5|. The beams are carried-on hangers 52 depending from the roof. Auxiliary beams 53 similarly support the lower ends of the ducts 46 and are carried on the beams 5| by hangers 54. The ducts 46, after they emerge from the roof 26, extend laterally from the longitudinal, central plane through the furnace and are connected to an offtake 55.

Referring now to Fig. 5 showing the fuel supply, system diagrammatically, fuel is supplied from any suitable source through a shut-off valve 56 and a master regulating valve 51 to the

manifolds

34 and 35. The manifolds 34 have valves 58 therein for discontinuing the supply of fuel under certain conditions which will be explaincd shortly. Similar valves 59 are disposed between the manifolds 48 and certain of the tubes 42. These valves 58 and 59 are of the type which closes automatically when the pressure of the fuel supplied thereto falls below a predetermined value. Such valves are well-known and require no detailed description.

The system shown in Fig. 5 makes possible highly efiicient operation of the furnace in that during the initial stages of the heating cycle, all the

tubes

30 and 42 may be fired at full capacity. When the charge is approaching the maximum temperature, however, and it is necessary only to allow sufficient time for the heat to soak entirely through the mass being treated, operation of the master control valve 51, either automatically or manually, throttles the fuel supply so that the pressure on the furnace side thereof is less than that required to maintain valves 58 and 59 open. As a result, the supply of fuel to alternate tubes 30 and to all of the tubes 42, except the two bottom ones in each bank, is discontinued. The tubes 30 connected to the manifolds 35 and the two bottom tubes 42 in each bank continue to supply heat to the charges thereby increasing their temperature at a reduced rate while permitting the heat previously supplied to the charges to soak entirely there: through. The two bottom tubes of each bank are continuously fired' because the heat supplied thereby to the charges naturally tends to rise a through the latter.

It will be evident from the foregoing description that the invention provides a furnace for annealing or otherwise processing material-which operates at high efficiency and, at the same time,

requires a minimum investment per ton of capacity. By. supplying heat to the charges from opposite sides, the temperatures of all parts thereof are raised at substantially the same rate. The

automatic shut-off of the supply of fuel to certain of the heating tubes makes possible a substantial saving in the fuel cost. While the furnace is intended particularly for the treatment of long narrow sheets, it may also be employed for treating coils. By employing tube banks extending into the furnace for only half the length thereof, the provision of the necessary supports therefor is simplified. In addition, better control of the distribution of heat in each individual tube is obtained. The fuel supply to each tube may be manually controlled by suitable valves. The connection between the tubes of each bank and the associated duct, furthermore, is such that adjustment of the fuel supply for one tube will not disturb the draft or combustion in adjacent tubes.

Although I have illustrated and described herein but a preferred embodiment of the invention, it will be understood that changes therein may be made without departing from the spirit of the invention or the scope of the appended claims.

I claim:

1. In a furnace including a roof and side walls, a bank of substantially horizontal heating tubes extending through a side wall thereinto, and an exhaust duct extending from the furnace substantially vertically through said roof, the inner ends of said tubes having a telescopic connection with said duct.

2. In a furnace, a bank of heating tubes extending thereinto, a master valve controlling the supply of fuel to said tubes for combustion, and valves which close automatically on reduction of the pressure of said fuel controlling the supply thereof to certain tubes of said bank.

3. In a furnace, a bank of heating tubes mounted therein, fuel supply manifolds to which said tubes are connected in groups, a master valve controlling the supply of fuel to said manifolds, and a valve which closes on reduction of the pressure of said fuel controlling the supply thereof to one of said manifolds.

4. In an annealing furnace, a base, a plurality of supports for charges of material arranged on said base in spaced rows, a cover having side walls, end walls, and a roof, adapted to be disposed on the base and overlie all said supports andcharges thereon, heat-exchange tubes extending upwardly along said side walls from points near the lower edges thereof effective to deliver heat to the outer sides of charges on said supports, substantially horizontal heat-exchange tubes extending inwardly from said end walls, and suspended from said roof between adjacent rows of charge supports for radiating heat to the inner sides of said charges, and exhaust tubes connected to said last mentioned tubes and extending substantially vertically through said roof.

'JAMES c. WOODSON.