US1778505A - Open-hearth furnace - Google Patents

Description

Oct; 14, 1930. s. NAISMITH 1,778,505

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Patented Oct. 14, 1930 UNITED STATES SAMUEL NAISMITH, b1? CHICAGO, ILL INOIS OPEN-HEARTS: FURNACE Application filed July 31,

This invention relates to a new and improved open hearth furnace construction and more particularly to a construction of such a furnace whereby the entire side of the fur- 5 nace may be open.

Open hearth furnaces as ordinarily constructed comprise a hearth, vertical back and front walls and roof, the walls and roof being formed of silica brick. The walls are non-removable and are supported by means of buckstays which also serve to support the sides of the hearth. The buckstays-also carry the longitudinally extending frame members which receive the lateral thrust of the roof which is arched in cross section. a The walls become undermined and cut away by the action of the slag during the operation of the furnace and then fall in. This results in considerable loss due to production of an inferior grade of metal when the walls fall in near the time for tapping the heat. It also results in considerable loss of time in rebuilding the' walls which work must be carried on under extreme conditions of heat. The arched roof also tends to be eroded or worn away adjacent the sides and requires replacement at considerable expense and loss of operating time.

In my prior patent, No. 1,536,038, covering a method for maintaining open hearth furnace walls, I have covered a wall construction which slopes upwardly and outwardly on such an angle as to maintain a layer of refractorymaterial on the wall for its protection. Thisform of construction is elficient and useful but it is impractical to supply front walls of this type when rebuilding existing furnaces due to lack of clearance on the charging floor. This wall construction can be used for back walls in such cases, and results in materially prolonging the life of the back walls. In this case, however, the front walls still burn out comparatively rapidly and are a limiting factor in the life of the furnace.

The furnace walls, as generally constructed, are provided with a plurality of openings covered by vertically movable doors. These doors are protected by brick linings and are sometimesprovided with water cooled frames.

1926. Serial No. 126,235.

The furnace is charged throughthese doors which thus limit the points at which the charge may be introduced. Their comparatively small size requires careful management of the charging machine unless the door arches or sides are to be injured or broken away in the charging operation. These small doors also limit thesize of material which can be charged and if scrap or other material is available in large pieces it must be broken up before charging which introduces additional expense.

It is an object of the present invention to provide a furnace construction having side walls composed wholly of movable members or doors.

It is an additional object to provide a construction of this character in which the roof supporting elements are located adjacent the ends whereby the furnace side or sides are entirely unobstructed.

It is an additional object to provide a flat suspended roof.

Other and further objects will appear as the description proceeds.

I have illustrated certain referred embodiments of my invention in t e accompanying drawings, in which Figure l is a longitudinal vertical section of one-half of a furnace equipped with my construction Figure 2 is a horizontal section of the furnace shown in Figure 1;

Figure 3 is a transverse section of the furnace shown in Figure 1; and

Figure 4 is a view similar to Figure 3 but showing a modified formof construction.

Referring firstto the form of construction shown in Figures 1, 2 and 3. The furnace comprises the hearth 11, of usual design, together with the gas port 12, gas uptake 13, gas slag pocket 14;, air uptakes 15 and slag ocket 16. These elements are all of usual design. The hearth 11 is supported upon the longi-' tudinal beams 17 and the transverse beams 18. The sides of the hearth are supported by the structural members 19 which are secured to the transverse members 18. These members 19 extend only to thelevel of the upper portion of the hearth.

The roof 20 comprises a plurality of bricks supported from the transversely extending I-beams 21. These I-beams are supported by hangers 22 from the upper portion 23 of the roof supporting structure. This structure is supported adjacent the ends of the furnace upon the vertical members 24 shown in Figure 2. The sides of the roof are engaged by the longitudinally extending water cooled members 25.

The sides of the furnace between the roof 20 and hearth 11 are closed by a plurality of doors 26. These doors as shown are constructed with a brick face and with a water cooled framework 27. The doors are raised or lowered by cables 28 passing over the pulleys 29 and 30 carried by the roof supporting structure. The upper edges of the doors engage the water cooled members 25 which thus protect the roof edges. Referring now to Figure 2, each door 26 is provided on one side with a flange 36 and upon the other side with a recessed flange 37. The flange 36 fits into the recess in the flange 37 of an adjacent door so that each door is guided in its movement by the doors upon each side of it. These interengaging flanges also serve to render the joints between the doors more nearly gas tight and minimize leakage of air into the furnace.

In the form of roof construction shown in Figure 1, the roof consists of a plurality of courses of brick 38 which are oppositely faced upon either side of the supporting I. beams 21. These brick are provided with recesses 39 which engage the enlarged lower portion or flange of the I beam. The meeting faces 31 of the brick are corrugated, which joint renders the brick mutually supporting and also makes the joint more tight; Between the spaced courses of brick 38 are provided pairs of courses of brick 32. The pairs of brick 32 are wedged between the brick 38. The adj acent faces 33 of the brick courses32 are also corrugated to assist in maintaining the brick in fixed relation and to makea tighter joint.

In the construction shown in Figure 4 the left side of the furnace is provided with the door construction identical with that described in connection with the prior figures. This would be the front or charging side of the furnace. The back wall 34 extends upwardly and outwardly from the level of the hearth to the roof and is preferably placed upon such an angle as to support a layer of refractory material which serves to protect the wall. This wall is supported by the buckstays 35 and the wall would be provided with the usual doors.

In the form of construction as shown in Figures 1 to 3, as many doors as desired may 'be raised at one time providing any desired opening for charging purposes. When the protective brick lining of any door becomes worn that door may be lifted up and out of place and a new door or previously repaired door may be quickly substituted without interruption of the operation of the furnace. This eliminates all of the difficult repair work on walls which normally is carried on under such heat as to render the work diflicult. The doors may be repaired at any convenient place when entirely cooled down. In this form of construction both front and back Walls may be taken care of in this way.

In the form of construction shown in Figure 4 the front wall through which the charge is introduced may be opened to any desired extent for that purpose. The doors also may be readily removed and replaced when necessary. The back wall, due to the protective layer of refractory material, has a very long life and will require rebuilding only at very long intervals.

The Hat roof which is suspended from a supporting structure can have such portions as are worn away readily replaced without affecting the remainder of the roof. This roof is flat and parallel to the upper surface of the bath and there will not be the tendency for the edges of the roof to be Worn away, as is the case with arched roofs where the sides are lower and close to the bath. Since the roof is flat there will be but little lateral thrust to be taken up by the water cooled side members 25. These members protect the edges of the roof and serve as guides for the movable doors.

While I have illustrated certain preferred embodiments of my invention in the accompanying drawings, I contemplate such changes and modifications as come within the spirit and scope of the appended claims.

I claim:

1. In an open hearth furnace, a hearth, a roof, an open side between the hearth and roof, and a plurality of vertically movable doors adapted to close said side, said doors being provided with interlocking portions whereby each door serves as a guide for adjacent doors.

2. In an open hearth furnace, a hearth, a flat roof, roof supporting columns located at the ends of the furnace whereby the side between the hearth and roof is entirely unobstructed by columns.

3. In an open hearth furnace, a hearth, a roof, roof supporting columns located at the ends of the furnace whereby the side between the hearth and roof is entirely unobstructed, and a plurality of movable members adapted to close said open side.

4. In an open hearth furnace, a hearth, a. roof, a side of the furnace being entirely unobstructed between hearth and roof, and cantilever hearth side supporting members extending upwardly and terminating adjacent the upper edge of the hearth.

5. In an open hearth furnace, a hearth, a roof, a. side of the furnace being entirely unobstructed between hearth and roof, cantilever hearth side supporting members extending upwardly and terminatin adjacent the upper edge of the hearth, roo support- I ing columns located adjacent the ends of the furnace, and a roof sup orting frame carried by said co1umns,'t e roof being suspended from said frame. Signed at Chicago, Illinois, thiSQixEfl day of July, 1926. SAMUEL n: g

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