US2325945A - Furnace door - Google Patents

Description

Aug. 3, 1943. o M. FUCHS FURNACE DOOR 2 Sheets-Sheet l Filed Jan. 26, 1942 IIIIIIIIIIIIIBII' I I l l i l I I IIIIIIII ||||\r| ||I lllllllllll IIJ m ./A-IllglLi-I-ll. @3 C l L d.: L

Aug- 3, 1943. o. M. Fuel-is 2,325,945

FURNACE DooR Filed Jan. 26, 1942 2 Sheets-Sheet 2 lNvENToR a @i M@ Patented Aug. 3, 1943 FURNACE DOOR Oscar M. Fuchs, Pittsburgh, Pa., assignor to Blaw-Knox Company, Pittsburgh, Pa., a corporation of New Jersey Application January 26,l 1942, Serial No. 428,205

(Cl. 11o-173) Claims.

This invention relates to a furnace door and, in particular, to a door suitable for use on openhearth furnaces.

Furnace doors of the type mentioned have heretofore generally been composed of a supportingY and enclosing structure or back, vconveniently fabricated from metal plate, and a lining of refractory brick laid therein. As an improvement over the brick lining, a layer of refractory material in plastic form has been applied to the inner surface of the door, in sufficient thickness to protect the back from the heat of the furnace. In the latter construction, it has been customary to secure studs or bolts to the inside of the back, adapted to be embedded in the plastic layer and anchor it to the back. The lining-and studs are subject to the hot gases of the furnace, which attack and burn the ends of the studs, causing flaking of the refractory. The studs are thus progressively consumed, and the life of the lining is limited thereby.

I have invented a novel furnace door which overcomes the aforementioned disadvantage of the construction previously known. In a preferred embodiment, I secure sockets on the inside of the back of the door, distributed over the surface thereof. In these sockets, I mount supports or studs adapted to be embedded in the filling or lining applied to the inside of the door in plastic form. The supports or studs are themselves composed of refractory material having a high resistance to the action of heat and a thermal conductivity greater than that of the refractory material composing the lining. A suitable material for the supports or studs is silicon carbide although any other material of suitable character may be used as well. The invention may be embodied in various forms, several ofwhich, as Well as the preferred embodiment, will be described in detail hereinafter by reference to the accompanying drawings illustrating typical forms. In the drawings,

Figure 1 is a front elevation of a door according to my invention with the lining of refractory material omitted;

Figure 2 is a section through the door taken along the plane of line II-II of Figure 1, showing the lining material as Wellas the studs in place on the inside of the door;

Figure 3 is a similar view taken along the plane of line III- III of Figure 1;

Figure 4 is a partial View similar to Figure 1 showing a further modification;

Figure 5 is a partial section taken along the plane of line V-V of Figure 4;

Figures 6 and 7 are detail views in elevation and section corresponding to Figures 4 and 5 with the lining proper omitted;

Figure 8 is a View similar to Flgurei showing a l further modification;

Figure 9 is a partial section taken along the plane of line IX--IX of Figure 8;

Figure 10 is a view partly in section and partly in elevation showing a portion of Figure 9'to enlarged scale with the lining proper omitted:

Figure 11 is a view Asimilar to Figure 9 showing a further modification; and

Figure 12 is a view similar to Figure 10 showing the modification of Figure 11.

Referring now in detail to the drawings and, for the present, to Figures 1 through 3, a furnace door indicated generally at I comprises a. body portion or back II ofv metal, which may conveniently be fabricated from suitable plate. The back I I is preferably hollow, and includes in addition to the panel Ila, flanges I2 extending inwardly therefrom which are also hollow, cooling Water connections I3, a sight hole it, and lifting lugs I5. A lining or front for the door indicated generally at I6 is applied within the flange I2 and is of refractory material to withstand the furnace heat to which it is subjected. The lining I6 is poured in place or otherwise applied, while in plastic form and sets either by chemical action or drying and burning. It may conveniently be composed of granulated refractory material such as chrome ore, made into plastic form by the addition of a suitable binder.

Before applying the lining I6, I mount supports or studs I1 on the inside ofthe back of the door and projecting inwardly thereof, adapted to be embedded in the lining. In the embodiment illustrated in Figures 1 through 3, the supports II are in the form of blocks of refractory material. They are secured to the door by cementing them between spaced bars I8 welded on edge to the inside of the back on opposite sides of spacer blocks i9. The bars I8 and blocks I9 thus provide sockets for receiving the inner ends of the studs HI. The supports or studs II form shelves spaced vertically and horizontally which are highly effective in supporting the lining and anchoring it to the door back.

The studs are preferably composed of refractory material having a thermal conductivity greater than ordinary refractory material such as silica bricks. The material of which the studs are composed, furthermore, has a high resistance to the action of heat, i. e., it has superior qualities as a refractory, and is much more resistant to heat than the metal o1' which the door back is made, but has a much lower conductivity. A suitable material for the studs I1 is silicon carbide. This material is availablecommercially in various forms sold under the trade-name "Carborundum. Any other material having similar characteristics, of course, may be used instead.

It will be observed that the spaces between adjacent studs I1 are staggered in successive rows of the latter. This arrangement tends to prevent any vertical flow of the lining material should it soften under the extreme heat of the furnace. The dimensions and spacing of the studs I1 may be varied over a considerable range but it will be apparent from Figure 1 that the ends of the studs I1 which are exposed, as illustrated in Figures 2 and 3, have an aggregate area which is a substantial proportion of the surface of the door exposed to the furnace heat.

The studs I1 perform several functions. In the first place, as already indicated, they serve to anchor the lining mechanically to the door back and support it against sagging or pulling away from the back. Inl addition, the studs, having a thermal conductivity greater than that of the refractory material in which they are embedded, serve to cool the latter by conducting heat therefrom to the inside of the back of the door through which cooling water circulates continuously. The

function of the studs I1 as supports is aided by' the fact that the material of the lining proper bonds firmly therewith. Because of the refractory nature of the material of which the studs are composed, furthermore, they are not subject to softening or oxidation. The durability of the studs tends to prolong the life of the lining. Because oi the qualities of silicon carbide, the studs do not burn away in the manner characteristic of metal studs, and thus maintain continuously the firm anchorage of the lining to the back of the door.

The door l may be of the Water-cooled type such as that shown in Williams Reissue Patent 17,864. In such constructions, the sockets for the studs I1 of Figures 2 and 3 or studs 32 of Figures 8, 9 and 10 are attached to or in heat-conducting contact with the water-cooled portion of the door.

Figures 4 through '1 illustrate a further modiiication according to which a door 26 similar to that shown at I0 has sockets 21 distributed over the inside surface thereof. The sockets 21 are conveniently composed of a pair of channels welded together with their anges in abutment, cut ofI in suitable lengths and welded to the inside of the back of the door. Studs 28 are cemented in the sockets 21 and a lling or layer 29 of refractory material in the form of a plastic is then applied in the manner previously described. The studs 28 and lining 23 are of the same composition as the lining I6 and studs I1.

the studs 34 are filled with the material forming the lining 33, thus protecting the pins Sffrom the furnace heat.

It will be apparent from the foregoing description that the invention is characterized by numerous advantages over furnace doors as previously made. The studs serving to support and anchor the lining, being of refractory material, are highly durable, even under the extreme temperatures existing on the interior of an openhearth fumace. Besides i'lrmly anchoring the lining to the metal back of the door, the studs conduct heat out of the lining to the water circulating through the back of the door and also prevent sagging of the lining. The improved bond between the silicon carbide studs and the material of which the lining is composed -has already been mentioned, as well as the fact that the studs are not subject to being burned away which would, of course, result in progressive destruction of the anchorage for the lining. The life of a door made according to my invention is considerably greater than that of doors known Figures 8 and 9 illustrate a further modification only difference being that the studs 34 are tubular and are cemented onto metal pins 35 secured to the inside of the door back as by welding. As shown in Figure 11, the spaces on the interior of previously. As indicated above, the studs may take various forms but in any case, the aggregate area of the exposed ends thereof constitutes a substantial portion of the surface of the lining exposed to the furnace heat.

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

I claim:

l. A furnace door comprising a heat-dissipating metal back', a plurality of anchoring members secured to said back in heat-conducting relation thereto and extending outwardly therefrom, and a refractory lining applied to said back embedding said members so as to be anchored thereby to the metal back, said anchoring members being composed of non-metallic refractory material having a thermal conductivity intermediate that of the metal of the back and that of the lining and being adapted thereby to convey a limited amount of heat from the lining to the metal back..

2. A furnace door comprising a heat-dissipating metal back, a plurality of silicon carbide anchoring members secured to said back in heat-conducting relation thereto and extending outwardly therefrom, and a refractory lining applied to said back and embedding said anchoring members so as to be anchored thereby to the metal back, said silicon carbide anchoring members having a thermal conductivity intermediate between that of the metal of the back and that of the lining and being adapted thereby to convey a limited amount of heat from the lining to the metal back.

3. A furnace door comprising a water-cooled metal back, a plurality of anchoring members secured to said back in heat-conducting relation thereto and extending outwardly therefrom, and a refractory lining applied to said back embedding said members so as to be anchored thereby to the metal back, said anchoring members being composed of non-metallic refractory material having a thermal conductivity intermediate that of the metal of the back and that of the lining and being adapted thereby to convey a limited amount of heat from the lining to the metal back.

4. A furnace door comprising a heat-dissipating metal back, a plurality of anchoring members extending outwardly therefrom and having plug and socket connections for securing said members to the back in heat-conducting relation thereto, and a-refractory lining applied to said back and embedding said members so as to be anchored thereby to the metal back, said members being composed of non-metallic refractory material having a thermal conductivity intermediate that of the metal of the back and that of the lining and being adapted thereby to convey a. limited amount of heat fromthe lining to the metal back.

5. A furnace door comprising a water-cooled metal back, a plurality of silicon carbide anchoring members extending outwardly from the back,

said back being provided with sockets `for sup- Y

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