US2670698A - Furnace roof - Google Patents

Description

C. G. POTH FURNACE ROOF March 2, 1954 Filed Jan. 26, 1951 2 Sheets-Sheet 2 Patented Mar. 2, 1954 2,670,693 FUEQNACE 15001 Ciereliee Ge Beth, .East Canton, Ohio,

' te Republic Steel Gerreretieri,

e.. corporation f New J ereey v assignor Cleveland, Ohio? Application Januar-y 26, 19571, Serial No. 208,010

0 Claims,

invention relates generally to wall con? struction iormetallurgical furnaces and is Dar,- ticularly concerned with a brick work-construction which is suitable for the ywalls of such turnaces which are subjected to the most severe serve ice conditions, such as the roof and knuckle walls of an open hearth furnace and electric furnace roofs.

Many efforts have been made heretofore to improve the roof construction of metallurgical furnaces, such as open hearth and electric furnaces used in the steel industry, but there is still much to be desired in the most highly de Veleped .reef eeiietriieteiie 0f the present day. Such roofs have a short life at best before patchinc ie required en@ repeated sete-,hiee must be debe frequently te lieee the furnace irl operation. Muehleriger reef life ie desirable beeauee ef the expense required for patching or replacing the patched roof, this expense including the, iossof Dreduetieii .dering the time the ierneee isv being so repaired.

There ere comparatively few materiele which are at all suitable for use as roof construction material in open hearth furnaces and the like. Chief among these materials are silica brick and betie briekf Sila blc are Well Suited t9 $119? 11S@ il? d numbr 0f JFSSDGS.- They are SOQgz bigii? t9 melt et e temperature ef approximately 3,999" F, and are resistant to erosionby gases. ever, the heet eenduetivity ef eiliee britte. ie considered only fair.

Basic bricks are. suitable for such use some reeeeete but Het in ether respeete Ae eeieeered with silica brick they are much heavier but they are weaker, more resistant to erosion and begin te melt et higher temperatures. Besie brieke ere so *heavyv that a large open hearth roof construct? ed of them must 'be supported by suspending meene- PFOPOSSS have been mage t0* 11s,@ 91.115 mear CQYQrSd bsf? brick ill ftlmae, .YQQ v3,01-5'01i1(5.?095 but such proposals have net Solved the. emblem because YQH Xd which Was ,fmd Q11 Q Dicke@ 117D by the double thekneee ei metal between tbe rows' of bricks resulted in growth of the bricks and resultant buckling andfspalling rof the roof.

The present invention is predicated on the dis.- covery that new and unexpected results may be obtained by utilizing in furnaces of the type here under consideration e Well eeiietriietien eemf Dl'vsllg rOWS 0i Smc@ bc 0n QQQQSQ Si Pf erle er tw@ .reve et betie britt eeeh ef the betie brieke, preferably but not necessarily, heise,

It has been found in cased in a metal shell.

actual practice that when furnaces have such a construction in the parts ofthe roof and knuckles heats as the best conventional furnace betweenV successive patchings As illustrative of these new and surprising result, it may be said that open hearth furnaces embodying the present invention have been operated to produce 50% more heats before the rst patching than was possible with the best conventional prior art roof construction.

The new and surprising results attained by the present invention are believed to be traceable to the new combination of parts and the new resulting mode of operation. The combination of silica and basic brick protects the construction against erosion, oxides and resultant spalling. This in turn strengthens the construction by bonding the bricks together. It enables the more highly conductive basic brick to conduct heat away from the silica brick and thereby keep the temperature of the latter at a lower level. The arrangement of the rows of silica and basic bricks prevents any material lateral growth and leepe blieb-.ling ef the reef et the minimum Ae a result the roof is light enough and strong eheheh eed there eed .site maintaining te be' self-supporting and not to require overhead supports, Moreover, the surfaces of the basic briikrwhch im? 53.229058@ t0 the gases rapidly pk .iiD .CITQQS oxide from the gases afld thus the Slizlfes Y the .inner Ser-feces ef ,the silice brieke.- ,This iti- Were eiteiisiee ef the beeie briek etree e Sert of washboard eect to the furnace wall and affords protection to the silica brick against the erosive effects of the gas since the rapid ilo-w of the gases is interfered with and the gases are agitated and are deflected away from the silica brick by the rib-like projection of the basic bricks.

The present invention will be better understood by those skilled in the art from the drawings which accompany and form a part of this speci# fication and in which:

Fig. l is an elevational view partly in section taken longitudinally of an open hearth furnace embdyng the present invention;

Fia i is a transverse, Sectional View et the:

furnace of Fig. 1;

ei .there brick grew inwardly revendY Fig. 3 is a perspective-like view of a part of the roof of Fig. 1 on an enlarged scale;

Fig. 4 -is a perspective-like view of a furnace roof embodying the present invention after having been in use for some time;

Fig. is a fragmentary, bottom, plan view of an electric furnace roof embodying the present invention; and

Figure 6 is a perspective view of one of the metal encased basic bricks.

In Figs. l, 2 and 3, the back wall of an open hearth furnace is indicated at i and part of the roof is indicated Iat 2. This roof includes rows 3 of basic brick encased in metal 3a and rows 4 of silica bricks. The rows 3 of metal covered bricks are preferably arranged in pairs, each pair extending varying distances from the back wall l so that the ends of adjacent rows in the roof do not lie on the same line longitudinally of the furnace. One or more rows of silica bricks may be interposed between two pairs of rows of the metal covered basic bricks. If desired, the basic bricks may be laid in single rows and one or more rows of silica brick may be laid between adjacent single rows of the basic bricks.

It has been found that it is unnecessary to extend the rows of metal covered basic bricks all the way across the roof of the furnace and when these rows extend upwardly along the roof approximately as is shown in Figs. l and 3, excellent results, in terms of the number of heats that can be made in a furnace before patching is required, may be expected.

Fig. 4 shows, fragmentarily, the appearance of the inner surface of the open hearth-furnace roof embodying the present invention after long continued use thereof. In this figure, 3 indicates rows of basic brick which were covered with metal, and 4 indicates silica brick, both as shown in Figs. l to 3. It will be noted that the lower or inner surfaces of the metal covered bricks have material 6 adhering thereto which projects downwardly well beyond the inner surfaces of the silica bricks. This material includes iron oxides which were carried by the gases and were deposited on the metal covering 3a of the basic bricks. This adhering material gives the inner surface of the roof a washboard effect as can be seen in Fig. 4, the effect of which configuration is that gases flowing along the roof are agitated and deflected away from the silica brick and the eroding effect of the gases is surprisingly decreased with resultant prolonged life of the silica bricks.

Fig. 5 shows the lower side of an electric furnace roof in which the basic brick 3 are arranged in rows extending along generally radial lines in the roof with the silica brick i completing the roof. While the arrangement of bricks in this roof is not exactly like that in the open hearth furnace roof of Figs. l to 4, this operation and results are substantially the same.

It has also been discovered, as a result of tests of this invention in roofs of metallurgical furnaces operating over long periods of time, that the basic bricks become fused to the silica brick during use and, hence, have a fairly good heat conducting connection thereto. The use of metal cases on the basic bricks improves the heat conducting contact with the adjacent silica bricks and thus act as good conductors to carry heat from the silica bricks into the basic bricks whence it may be carried away more rapidly than through'A the silica bricks themselves with resulta-nt maintenance of the roof at a lower temperature than would otherwise be the case.

In the appended claims the expression complete solid wall or roof wall refers to the brick portion of the wall or roof and is not intended to exclude openings such as the electrode holes in the roof of the electric furnace of Figure 5.

Having thus described the present invention so that others skilled in the art may be able to understand and practice the same, I state that what I desire to secure by Letters Patent is defined in what is claimed.

vWhat is claimed is:

1. A complete solid wall for a metallurgical furnace comprising a plurality of rows of silica bricks and a plurality of composite rows of bricks arranged alternately with said rows of silica bricks, each of said composite rows consisting of basic bricks disposed in juxtaposed relationship with each other thereby constituting a continuous part of said row and silica bricks constituting the remainder of said row, the numbers of basic bricks being diierent in adjacent composite rows with the basic bricks at one end of the basic brick parts of said rows being positioned in staggered relation relative to each other.

2. A complete solid wall for a metallurgical furnace comprising a plurality of rows of silica bricks and a plurality of composite rows of bricks arranged alternately with said rows of silica bricks, each of said composite rows consisting of basic bricks constituting a continuous part of said row and silica bricks constituting the remainder of said row, the numbers of basic bricks being different in adjacent composite rows with the basic bricks at one end of said rows being positioned in staggered relation relative to each other, and ferrous metal covering the surfaces of the basic bricks which are exposed to gases in the furnace.

3. In a metallurgical furnace having a chamber defined in part by an upstanding wall, a complete roof wall comprising a plurality of rows of bricks extending from said wall upwardly and inwardly and partly defining said chamber, certain of said f rows consisting of silica bricks, and certain other composite rows consisting of basic bricks and silica bricks with the basic and silica bricks con-l stituting respectively the parts of said composite rows adjacent to and remote from said wall, theA basic brick portions of some of said composite rows being shorter than the basic brick length of certain other rows of bricks.

4. In a metallurgical furnace having a chamber defined in part by an upstanding side wall, a complete roof wall comprising a plurality of' transverse rows of bricks positioned to extend upwardly and at an angle to said side wall of the furnace, certain of said rows consisting of silica bricks and certain other rows arranged alter-I nately therewith and consisting of basic bricks positioned to extend upwardly from said side walll and silica bricks to extendfrom the upwardmost basic bricks, the upwardmost basic bricks in adjacent composite rows being positioned to lie at different distances from said side wall and in4 upwardly and at an angle to said side wall of theV furnace, certain of said rows consisting of silica` bricks and certain other rows arranged altei-, nately therewith and consisting of basic bricks' positioned to extend upwardly from said side wall and silica bricks 1z0/extend from the upwardm'ost basic bricks, the upwardmostvbasicv bricks in adjacent composite rows being positioned to lie at different distances from said side wall and in staggered relation relative to one another, and ferrous metal covering the surfaces of the basic bricks which are exposed to furnace gases.

6. In an open hearth furnace having a chamber defined in part by upstanding front and back walls, a complete roof wall comprising a plurality of transverse rows of bricks positioned to extend from the back wall of the furnace to its front wall at substantially right angles to said walls, certain of said rows consisting'v of silica bricks and certain other rows arranged alternately therewith and consisting of basic br'icks positioned to extend forwardly from the back wall and silica bricks extending from the forwardmost basic bricks to the front wall, the forwardmost basic bricks in adjacent composite rows lying at different distances from the back wall and in different planes extending .longitudinally of the furnace.

7. In an open hearth furnace having a chamber defined in part by upstanding front and back walls, a complete roof wall comprising a plurality of transverse rows of bricks positioned to extend from the back wall of the furnace to its front Wall at substantially right angles to said walls, certain of said rows consistingof silica bricks and certain other rows arranged alternately therewith and consisting of basic bricks positioned'to extend forwardly from the back wall and silica bricks extending from the forwardmost basic bricks to the front wall, the forwardmost basic bricks in adjacent composite rows lying at different distances from the back wall and in different planes extending longitudinally of the furnace, and ferrous metal covering the lower exposed surfaces of said basic bricks.

8. In an electric furnaceV having a chamber defined in part by an upstanding generally circular outer wall, a completer roof wall comprising a plurality of generally radial rows of bricks positioned to extend from the outer wall of the furnace to its center, certain of said rows consisting of silica bricks and certain other rows arranged alternately therewith and consisting of basic bricks positioned to extend from said periphery toward the center of the roof and silica bricks extending from the innermost basic bricks toward the center of the roof, the innermost basic bricks in adjacent rows containing basic bricks lying at different distances from the said periphery and in different circles concentric with said periphery.

9. In an electric furnace having a chamber defined in part by an upstanding generally circular outer wall. a complete roof wall comprising a plurality of generally radial rows of bricks positioned to extend from the outer wall of the furnace to its center, certain of said rows consisting of silica bricks and certain other rows arranged alternately therewith and consisting of basic bricks positioned to extend from said periphery toward the center of the roof and silica bricks extending from the innermost basic bricks toward the center of the roof, the innermost basic bricks in adjacent rows containing basic bricks lying at different distances from the said periphery and in different circles concentric with said periphery, and ferrous metal covering the lower exposed surfaces of the basic bricks.

CLARENCE G. POTH.

References Cited in the le of this patent UNITED STATES PATENTS Number Name Date 1,672,524 Groninger June 5, 1928 1,686,386 Loftus Oct. 2, 1928 1,929,073 McDonald Oct. 3, 1933 2,068,863 j Mannshardt Jan. 26, 1937 2,085,837 Thomas July 6, 1937 2,216,813 Goldschmidt Oct. 8, 1940 2,236,920 Robertson Apr. 1, 1941 2,304,170 Heuer Dec. 8, 1942 FOREIGN PATENTS Number Country Date 807,010 France Oct. 5, 1936

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