US1226264A - Electric furnace. - Google Patents

Description

F.C.SCHM1TZ.

ELECTRIC FURNACE.

APPLICATION FILED NOV. 3. 1913.

Patented May 15, 1917.

4 SHEETS--SHEET F. 0. SCHMITZ.

ELECTRIC FURNACE.

APPLICATION FILED NOV. 3. 1913.

Patented May 15, 1917.

4 SHEETS-SHEET 2.

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"F. p. SCHMITZ. ELECTRICFURNAQE. APPL ICATlON FILED NOV. 3. 1913.

Patented May 15, 1917,

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F. C. SCHMITZ.

ELECTRIC FURNACE.

APPLICATION FILED NOV. 3. 1913 1,226,264. Patented May15,1917.

4 SHEETSSHEEI 4.

FRANK C. SCHMITZ, OF NEW YORK, N. Y. i

v ELECTRIC FURNACE.

Specification of Letters Patent.

Patented May 15, 1917.

Application filed November 3, 1913. Serial No. 798,922.

To all whom it may concern Be it known that I, FRANK C. ScHMrrz,

a citizen of the United States, residing at new and useful improvements in electric furnaces of the water-cooledt'ype pand more pal'ticularly to furnaces especially designed for reducing or melting phosphate rock in the production of phosphoric acid, although furnace structures built in accordance with thepresent invention will be found to be serviceable inthe treatment of other materials, especially where high heat is required to effect reduction.

Much difficulty has been experienced and many failures have resulted from the attempts heretofore made to use known con structions of furnaces in the treatment of phosphate rock to produce phosphoric acid P 0 gas, owing largely to the chemical action of the highly heated molten material and slag upon the furnace walls, especiallywhen the phosphate rock is melted in the presence of silicious material. It has been demonstrated under actual working conditions with a mason-work furnace lined with silica and other fire-brick, that the furnace lining as well as its thick walls are soon eaten away and totally destroyed by the chemical action thereon of the molten mass within the furnace, the life of the furnace being of comparatively short duration. Attempts have been made to provide a furnace with a metallic water-cooled pot, but these, so far as I am aware, have not proved entirely successful owing to certain structural defects, such for instance as ineflicient provision for proper circulation of the cooling medium, inability to remove and repair or replace a defective or. burned-out watercooled pot; and liability of short circuits between the electrodes and metal parts of the water-cooled pot resulting in destruction of the latter and of the entire furnace structure. One object of the present invention is to provide a furnace structure of simple con struction, built upon scientific lines and possessing the necessary strength and durability to withstand the destructive influences arising during operation.

A further object of the invention is to provide a novel and simple construction of water-cooled slag-pot, cooling of the pot being effected through the medium of a plurality of independently insertible and removable water-cooled units, the purpose being to provide a water-cooled wall structure made up of independent water-cooled units any one of which may be removed at will, as in case of a defect appearing or developing, and a new unit substituted therefor, without disturbing the remainder of the furnace structurev and without shutting down the reducing operation.

A further object of the invention is to provide novel and simple means for supporting the separate water-cooled units whereby they may be easily and quickly removed and replaced.

A still further object of the invention is to provide a novel and simple construction of furnace superstructure constructed of steel and concrete on scientific principles.

Another object of the invention is to provide a. furnace structure of the character described with water cooled means for separately tapping therefrom different slag formations.

Another object is to provide a novel construction and arrangement of water-cooled jacket for the electrodes.

With these and other more or less important objects in view, the invention re sides in the features of construction and novel combinations and arrangement of parts herein shown and described and then i more definitely pointed out in the claims.

Fig. 2 is a vertical longitudinal section.

F ig. 3 is a part transverse section and part rear elevation.

Fig. i is an enlarged detail view partly 5 in section and partly in elevation of one of the water-cooled plates or units, showing the means for supporting the same in posi tion, and showing also the inlet and outlet pipes for the cooling medium.

| Fig. 5 is a view in vertical section of the water-cooled jacket for the electrodes.

Fig. 6 is a perspective view of the metallic superstructure for the furnace.

In the present embodiment of the invention I have shown a furnace construction wherein only a single pair of electrodes is employed, but it will be obvious that the same construction may be employed in connection with furnaces having more than one pair of electrodes, the showing here being merely by way of example.

The foundation for the furnace may conveniently consist of a pair of spaced concrete walls 1 upon the upper face of each of which may rest a wooden beam 2 preferably consisting of oil treated timber, this being for insulating purposes. At its front the furnace is preferably provided with a concrete slag pit3 into which the molten slag from the furnace may flow, the pit containing water in orderthat the hot slag may be immediately cooled and disintegrated upon its discharge into the pit.

The furnace super-structure consists in the instance shown of a pair of I-beams &

of inverted arch or cradle form, one resting upon each of the spaced walls 1. Each cradle beam is supported by a pair of upwardly and inwardly extending supporting posts 5 which preferably consist of I- beams, each post being secured at its upper end toone of the upper ends of thecradle beam by means of angle .plates 6 and the said posts being secured at their lower ends to the wooden beams 2 by means of lag screws as more clearly shown in Fig. 3.

The cradle beams 4 rest upon the Wooden beams 2 and these cradle-beams are further supported by means of metal feet 7, each riveted at its upper end to the cradle beam,

and secured at its lower end to the wooden beam 2 by means of lag screws.

The top or upper wall 8 of the furnace is preferably constructed in the form of an 65 arch made of silica or other fire-brick, the

said arch beingsupported at itsopposite ends upon the web portions of a pair of horizontally arranged I-beams 9, which I- beams rest upon the posts 5 and are secured in position by means of theangle plates 6 that connect the cradle-beams with said osts. Y

Each of the upright posts 5 at the front of the furnace has attached thereto near its upper end a step bracket 10, upon which figure. It will thus be noted that each yoke that covers the upper front wall 13 being riveted along its lower edge to the upper flange of the transversely arranged I-beam 12, all as more clearly shown in Figs. 1 and 2. I

The bottom and side walls of the furnace, which walls constitute the support for the 30 slag pot are curved, that is, in the instance shown, they are made on curvilinear lines conforming to the shape of the cradle beams and supported by the latter. This curvilinear wall consists of a plurality of regu-. g5 larly spaced supports shown as consisting of I-beams 16 extending longitudinally of the furnace, that is, they are substantially parallel with the elements of the curved wall, and each beam rests at its opposite ends upon the pair of cradle beams and is secured thereto by rivets. Each of the said I-beams 16 is partially embedded within a body of concrete 17 forming a reinforced concrete beam, the inner flange being en r 5 bedded, and the lower flanged portion of each beam being exposed for ,a purpose presently to appear. I

The spaces or cells between the reinforced concrete beams are of uniform length and width and insertibly and removably sup ported'in each of said spaces is a hollow water cooled plate or unit 18, which plates' or units serve to maintain the furnace wall sufficiently cool to prevent destruction thereof and of the slag pot during the operation of the furnace.

The water cooledplates or units 18 are removably supported in position between the spaced concrete beams 16 referred to by means of steel yokes 20, which yokes extend transversely of the units and rest at their opposite ends upon the exposed flanges of the I-beams 16, as more clearly shown indetail in Fig. l, the water cooled units being moved forwardly to be seated and securely held in position by means-of wedges 21 driven between the said yokes and plates, as more clearly shown in said 1.20 20 engaging with the flanges of the adjacent I-beams 16 constitutes a positive means for locking the water-cooled unit in its cell, as contradistinguished from merely holding the unit in place by the frictional engagement of the walls of such unit with the walls of the cell. Furthermore, such locking means is independent of the cell itself so that it may be readily manipulated to retain the cell in position or release the, 130

the water-cooled units may be positively forced inward to the desired position. The yokes therefore, constitute means for removably supporting the cooling plates or units in position between the beams so that any plate or unit may be removed at will in case a defect is shown or develops, and a perfect unit substituted therefor. This is a matter of great advantage and importance because the substitution of one plate for another may be made without shutting down'the operation of the furnace and furthermore any unit may be added or removed without disturbing any of the other units and also without in any way altering or tearing down any part of the superstructure or any part of the furnace walls. Repairs may thus be easilyand quickly made and at a minimumcost.

I prefer to make and arrange the cooling plates or units 18, in alined pairs as more clearly shown in Fig. 2, and between each of the pairs of units I provide a reinforced concrete cradle or band 22, that follows the general contour of the bottom and sides of the furnace, the reinforcing means consisting of straps or rods 23, connected at their opposite ends to the longitudinally extending beams 16, as more clearly shown in Figs. 2, 3 and 4.

The rear wall of the furnace, as more clearly. shown in Figs. 2 and 3 is constructed substantially like the bottom and side walls and consists of a plurality of regularly spaced transversely arranged truss-beams 24, each partially embedded in concrete 25, there being also vertically arranged concrete connecting blocks 26, between adjacent beams as more clearly shown in Fig. 3, to provide cells or spaces for the removable rear-wall cooling-plates or units 18, which units are removably supported by the yokes 20 and wedges'21 similar to those heretofore described. It is possible therefore to remove at will, for replacement or repair either of such rear-wall cooling units without disturbing any of the others and without tearing down any part of the superstructure or the walls of the furnace.

The front wall of the furnace as more clearly shown in Figs. 1 and'2 is constructed substantially like the rear wall just referred to in so far as its truss beams 24, and cooling plates or units 18 are concerned, and these parts need not therefore be further described.

I prefer to line the inner, bottom, side and end walls of the furnace chamber with metal plates 27, joined at the angles by means of angle irons 28, as shown in Fig. 2. The slag pot 29 of the furnace consists of a cementitiouscomposition consisting of a mixture of ground slag and cement, the latter forming about 5% of the mixture. The slag emat its inner or hottest point.

ployed is preferably that resulting from the melting or reducing of phosphate rock and silica. This material I have found to be admirably suited to the purpose because it does not appear to deteriorate appreciably by the reducing or melting operation, sinceit contains practically no phosphoric acid or silica and the fresh rock and silica fed into the furnace does not, therefore, attack the same, as it does in cases where the slag potconsists of silica brick. This cementitious mixture of slag and cement is spread several inches thick around the inner walls of the furnace chamber and is applied with. a trowel when in plastic form.

In order to tap the molten slag and phosiron from the furnace, I provide in the front nace, and'the other spout 31 being located above the spout29, as more clearly shown in Figs. 1 and 2. There is a downwardly inclined slag chute 30 extending outward below the spout 30, and a similar chute 31 arranged below the spout 31. These are for separately conveying the molten slag into the slag pit 3, as it flows from the slag pot so that the different slags may be tapped off separately, both being marketable products, the one being phos iron and the other a silicious slag that may be employed in the manufacture of bricks or ground and used as a fertilizer filler or otherwise employed.

Each of the tap spouts 30 and 31 consists of a double walled shell preferably made of bronze or a composition in which bronze predominates, and each is preferably of frusto-conical shape. These tap spouts are water cooled, the cooling water entering the spouts through inlet pipes 32' and 33 respectively, said pipes being pipe-connected to a water main 34 common. to both spouts. I prefer to lead each inlet pipe 32 longitudinally through the hollow tap spouts with its inner end terminating at a point slightly removed from the smaller end of its spout so that the cooling water will enter the spout The cooling water is led off from each tap spout by means of an outlet pipe 35 secured to the forward end of each spout, each outlet pipe having a downturned end arranged directly above the i slag chute associated with its spout, so that the outflowing water will serve to cool the slag as it flows out through the spout.

In melting or reducing phosphate rock and silica combined to form phosphoric acid,

.there is formed in addition to the slag a certain amount of what is known as phos iron and this being the heavier collects in the bottom of the slag pot. The phos iron is tapped off through the lower tap spout 30 and the phosphate is tapped off through the tap spout 31. The tap spouts are usually closed by means of a suitable plug, and these may bcremoved at will to draw olf either the phos iron or the phosphate slag.

The object in melting or reducing the phosphate rock and silica is to drive off the phosphoric acid which is eliminated in the form of a gas or fumes. These are conducted to a tower (not shown) where they are sprayed with water or a weakacid solution to obtain phosphoric acid in solution. The furnace as herein shown and described is provided at its rear end with a gas outlet 36, leading off from above the slag pot, the upper wall of said outlet being formed by an extension of the top arch of the furnace and the lower wall 38 of which is formed of reinforced concrete, said lower wall having a lining 39 of fire brick. The extended por tion of the top arch of the furnace constituting the upper wall of the gas outlet is supported by extended portions of the longitudinally extending I-beams 9, as more clearly shown in Fig. 6 and the bottom wall 38 of the gas outlet is supported by means of a transversely arranged I-beam 40, said I-beam being suspended by means of hangers 41 from the extended portions of the I-beams 9,

' as more clearly shown in said figure.

I prefer to provide the bottom wall 38 of the gas outlet with a cooling plate or unit 18 as more clearly shown "in Fig. 2, this plate or unit being removably inserted in a space or cell formed in the wall structure and held in place by means of yokes L2 similar to those heretofore described, the said yokes resting at their opposite ends respectively upon the angle beams l3 and 43, one

of which is riveted directly to the transverse I-beam 40, and the other of which is embedded in the concrete wall.

A cooling medium such as water is fed to the various cooling plates or units of thefurnace by means of pipe connections from a water main 44;, Fig. 1, and the cooling medium is returned from the plates or units by means of pipe connections leading to a return pipe 415, said water feed and return pipes having separate inlet and outlet connections respectively with each water plate or unit and the main feed and return pipes being common to all of said connections. I prefer to provide the feed and return pipe connections nection leading to the various cooling plates or units in order to facilitate removal and replacement of the various units'and in order to lend safety to the structure, the flexible unions or pipe connections 46 constituting automatic blow outs in case the pressure in any one of the water cooled plates or units becomes so great as not to be taken care of'by the feed and outlet pipes.

The material to be treated is fed to the furnace through a hopper f? supported upon the top wall of the furnace, said hopper being disposed above an opening &8 leading into the furnace chamber directly above and centrally of the slag pot 29. The feed opening 48 is normally closed by means of a bell cover 49 in the usual way, all as more clearly shown in Fig. 2.

The material is heated by a pair of inclined or converging carbon electrodes 50 that extend through the arched top wall of the furnace so that their lower ends may be brought sufliciently close to bring about a proper electrical arc, the electrodes being adjustable vertically by any suitable means, not shown.

Experience has shown that these carbon electrodes deteriorate by the action thereon of the hot gases or fumes within the fur nace, and in order to protect the same I propose to surround each electrode with a water cooled jacket, each jacket consisting of a pair of spaced metallic cylinders 51 one located within the other and connected at their ends by means of annular rings, and into each of which is led a pipe 52 for inlet of the cooling medium, and out of which leads an.

outlet pipe 53 for return of the cooling water, said inlet and outlet pipes being pipe connected respectively to the main feed pipe, and main return pipe as more clearly shown in Fig. 1. I prefer to lead the water inlet pipe of each cooling jacket thereinto longitudinally so that its outlet end terminates at a point slightly removed from the lower end or closure ring of the jacket so that the inflowing cooling water will enter the jacket at its hottest point. I also prefer to provide each inlet and outlet pipe with a cut off valve 54:, and I also prefer to provide each inlet and outlet pipe with a flexible connection or pipe section 55, which flexible connections or pipe sections serve as safety blowouts, all as more clearly shown in Fig. 3.

In order to support and attach the electrode cooling jackets to the arch wall of the furnace, I provide each with an annular angle iron 56, one member of which is riveted to the jacket and the other member riveted to a supporting ring 57, riveted to the furnace arch.

It is desirable to prevent air from entermg the furnace around the carbons as it has been found that this results in the car- I bons burning away, and to prevent the entrance of air through the annular space between the jacket and its carbon I provide a suitable packing to close the space. As more clearly shown in Fig. 5, the packing consists of an angle ring 58, and a fiat annulus 59, between which is located one or more asbestos rope packing rings 6, which latter closely embrace the electrode and close the surrounding space. The packing means is .not attached. to the electrode but is supported upon the outer end of its jacket, the electrode being free to move through the packing.

From the foregoing description taken in connection with the accompanying drawings, it will be seen that I have provided a furnace structure with novel and simple means for maintaining the furnace walls sufficiently cool to withstand the effects of the highly heated material within the furnace, and I have also provided means whereby the cooling plates or units may be easily and quickly removed in case any of the units develop flaws or defects, the construction and arrangement of parts being such that removal of any unit may be effective without shutting down or cutting off the operation of the furnace, and without removing any part of the furnace superstructure or tealrling down' any portion of the furnace wa While I have herein shown and described a preferred embodiment of the invention I do not wish to be understood as limiting myself to the precise details of construction .herein shown and described, except as I may be limited by the terms of the appended claims, as I am aware that minor changes or additions may be made to the structure without departing from the spirit of the mvention.

What I claim is 1. In a furnace, a slag-pot having a curved bottom and side walls, and having substantially vertical end walls, a plurality of substantially parallel bars extending longitudinally with the elements of said bottom and side walls, a plurality of substantially parallel bars at said end walls, said walls having cells or spaces formed therein between said bars, and a plurality of watercooled units held in said spaces, said bars being partially embedded in said walls and having flanges exposed on the outer sides of said walls, and means for engaging saidfianges to secure the said water-cooled units in said cells.

2. In an electric furnace, a pair of cradlebeams, reinforced concrete supports secured at their opposite ends to said beams, and cooing plates or units located between and supported by said concrete. supports.

' 3. In an electric furnace, a pair of spaced cradle beams, spaced supports spanning said their opposite ends to said beams, cooling plates or units located between said supports, and means for removably supporting said cooling plates or units.

5. In an electric furnace, a pair of spaced cradle-beams, parallel supports arranged in spaced relation to each other and secured at their opposite ends to said beams, cooling plates or units located between said sup ports, and means for removably supporting said cooling plates or units, said means resting upon the parallel supports.

6. In an electric furnace, a air of spaced cradle-beams, a plurality of I- beams secured at their opposite ends to said cradle beams and arranged parallel to each other, cooling plates or units located between said I-beams, means forremovably'supporting said cooling plates or units, and means for supplyin a cooling medium to the plates or units.

In an electric furnace, ,a pair of spaced cradle-beams, a plurality of metal beams secured at their opposite ends to said cradle beams'and arranged parallel to each other, each of said parallel beams being partially embedded in concrete, cooling plates or units removaby supported between the concrete portions of said parall l beams, and means resting upon the unembedded portions of the concrete beams to removably support the cooling plates or units.

8. In an electric furnace, a pair of spaced cradle-beams, upright posts to which the opposite ends of said beams are secured, parallel supporting beams secured at their opposite ends to said cradle beams and arranged in spaced relation, cooling plates or units removably supported in the spaces between said parallel beams and removable means supported by the parallel beams for holding the cooling plates or units in position.

.9. In a furnace structure, a pair of spaced cradle-beams, upright supports secured to the opposite ends of said cradle-beams for supporting the latter, a plurality of spaced beams secured at their opposite ends to said cradle beams and arranged parallel to each other, separate cooling plates arranged between each pair of parallel beams, means for feeding cooling Water to said cooling plates, a pair of arch supporting beams secured to the ends of the cradle beams, and a furnace arch supported by said arch supporting means.

10. In a furnace, a superstructure embodying cradle-beams, upright supports to which the opposite ends of said cradle beams are secured, spaced beams secured at their opposite ends to the cradle beamsand arranged in parallel relation to each other, and longitudinally extending arch-supporting beams spanning the cradle beams and secured thereto.

11. In a furnace, a superstructure embodying a pair of cradle-beams, upright beams to the upper ends of which the cradle beams are secured, parallel beams spanning,

the cradle beams and secured thereto at their opposite ends, said parallel beams being arranged in spaced relation to each other, and longitudinally extending archsupporting beams resting upon the ends of the cradle beams and upright beams, and means for securing the latter named beams to the web portions of the arch supporting beams.

12. In a furnace, a superstructure embodying cradle-beams, upright beams to the upper ends of Which the cradle beams are secured, parallel beams spanning the cradle beams and secured thereto at their opposite ends, arch-supporting beams secured to and resting upon the opposite ends of the cradlebeams and the upper ends of the upright supports, and transverse beams forming parts of the front and rear Walls of the furnace.

13. In an electric furnace, a metal superstructure, including a plurality of snbstantially parallel bars, Walls supported thereby partially embedding said bars and having a plurality of water-cooled units embodied therein between said bars, means for causing I a cooling medium to flow through each cooling unit, a furnaceiarch supported by the superstructure, electrodes extending through said arch into the furnace, a slag-pot, and a tap-spout leading from the slag-pot through a wall of the furnace.

14:. In an electric furnace, a metal superstructure including a plurality of metal bars, Walls partially vembedding the same, and having a plurality of water-cooled units embodied therein between said bars, means for removably supporting said units, means for causing a cooling medium to flow through each cooling unit, a furnace top wall supported by the superstructure, electrodes extending throughsaid top wall into the furnace, a slag-pot, and a tap-spout leading from the slag-pot through a wall of the furnace.

having a slag-pot, a water-cooled slagspout 15. In a furnace of the character described leading from said pot, means for introducing cooling water into said spout, and means for discharging the outflowing cooling water across the outlet end of the spout.

16. In a furnace, a slag-pot, a water-cooled slag-spout leading from said pot, a chute below the spout, means for introducing cooling" Water into the spout, and means for discharging the outfiowing cooling water across the outlet end of the spout and toward said chute.

17. In a furnace, a wall structure, a cooling plate or unit removably supported in a cell formed in the Wall structure, and means for causing a cooling medium to flow through said plate or unit, said means embodying a flexible pipe section.

18. In a furnace of the character deand a slag resulting from the reduction of phosphate rock and silica.

20. In a furnace, a furnace chamber and a slag-pot therefor, said pot being composed of a cementitious material made from cement and a slag which results from the melting of a mixture of phosphate rock and silica.

21. In a furnace, a wall, metal bars having flanges embedded in said wall and having flanges on the exterior of said wall, said wall having a plurality of cells or spaces between said bars, water-coo1ed units received in said cells, and means for holding said watercooled units in said cells.

22. In a furnace in combination, a wall having a plurality of cells, cooling units adapted to be received in said cells, circulatingpipes disposed near said wall, means for nesses.

FRANK O. SCHMITZ. Witnesses:

J. GRANVIILE MEYERS, E. H. BICKERTON.

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