US2451679A

US2451679A - Furnace lining structure

Info

Publication number: US2451679A
Application number: US601520A
Authority: US
Inventors: Stanley A Komorowski
Original assignee: Carnegie Illinois Steel Corp
Current assignee: Carnegie Illinois Steel Corp
Priority date: 1945-06-25
Filing date: 1945-06-25
Publication date: 1948-10-19
Anticipated expiration: 1965-10-19

Description

@4252. 19, 1948.. s. A. KOMOROWSKI 2,451,379

FURNACE LINING STRUCTURE Filed June 25, 1945 MJQLI W CA I 0 E w w WE M M Hm I! LQMAPJ, flu Tw M w N 1 W N M fln Y. CL L m 5 0A AU 4 M gill... m nHUP Patented Oct. 19, 1948 4 Elaims. E

Tins invention relates to a method of and apparatus for removing the refractory linings in furnaces.

The invention has among its objects the pro vision of a method for quickly and conveniently loosening the furnace lining and for removing it from the furnace.

A further object of the invention lies in the provision of apparatus for readily loosening the furnace lining preparatory to its removal from the furnace, and for catching the loosened lining as it falls into the furnace, thereby facilitating its removal. I

These and further objects of the invention will become more apparent in the following description.

The method and apparatus of the present invention display advantages in various types of furnaces in which the linings must be periodically renewed by reason of their deterioration by the contents of the furnace, the furnace atmosphere, or the high temperature to which they are subjected. The invention will be described in connection with its use with an electric furnace, but it is to be understood that it may be used to advantage in various other types of furnaces. The electric furnace chosen tdbedescribed to illustrate use of the present invention is shown in the accompanying drawings, in which:

Figure l is a view of an electric furnace in horizontal section taken along the line II in Figure 2;

Figure 2 is a view in vertical section through the furnace taken along the line 11-11 in Figare l;

Figure 3 is a View in side elevation of an insert or pull-out plate employed in connection with the lining of the furnace;

Figure 4 is a view in end elevation of the insert shown in Figure 3;

Figure 5 is a view in side elevation of a larger insert suitable for use at a furnace opening, such. as the tapping spout; and

Figure 6 is a View in end elevation of the insert shown in Figure 5.

The electric furnace shown in Figures 1 and 2 is of the three-phase, three-electrode type, generally known as the Heroult electric furnace. It consists of a generally cylindrical metal shell 2 through which suitable side openings are provided, such as the charging door 4, the operating door I, and the tapping spout 8. The furnace, which is provided with a refractory bottom and with side linings, presently to be described, is further provided, when in operating condition.

UNITED STATES PATENT OFFICE FURNACE LINING STRUCTURE Stanley A. Komorowski, Chicago, 111., assignor to Carnegie-Illinois Steel Corporation, a corporation oi. New Jersey Application June 255,, 1945, Serial No. 601,529

with an arched refractory roof is through which project three electrodes it between which the arc is struck and maintained to provide heating means for the furnace. Roof no is removable for the purpose of relining the furnace, and electrodes l2 are mounted upon pivoted electrode holders i l, schematically shown in Figure l in inoperative position, so that they can be swung to the side or" the furnace to permit removal of the roof.

The bottom so of the furnace is formed by layers of refractory material it resting upon the bottom metal plate to of the furnace which is secured to the shell 2. The hearth oi the furnace, within which is contained the bath of ma" terial, for example, molten metal, is formed of a layer of granular material, such as burned magnesite grain sintered in place in the case of a basic furnace. Adjacent the top edges of the bottom 20 and resting upon the side portion of the furnace bottom foundation to is a relatively thick layer of refractory 22 which will be called the top supporting hearth briclz.

The lining of the furnace, which is that portion normally above the bath in the hearth, is laid within shell 2 and rests upon the top supporting hearth brick. Such lining in the rear of the furnace, that is, adjacent the charging door, is designated 24 Whereas that in the front of the furnace adjacent the tapping spout is designated 26 at the bottom thicker portion thereof and 28 at the upper portion which has a thickness comparable to that at the rear of the furnace. Part 28 is made of such increased thickness because the furnace is of the tilting type and the metal and slag rises into contact with such portion 2% of the lining when the furnace is tilted to discharge the melt.

When an electric furnace of the type shown and described is employed in the production of steel, the lining must be renewed after an average of seventy to eighty heats of steel have been produced, or after thirty-five or forty days of continuous operation. The relining operation consists in removing the refractory wall brick from the top supporting hearth brick to the roof and replacing it with new furnace brick. The normal time required for relining varies from twenty-four to thirty hours, depending upon the difllculties encountered in removing the old lining. Removal of the lining has been accomplished, according to prior art practices, by first removing the electrodes and roof of the furnace, and placing a, water-cooled plate within the furnace to cover the entire bottom thereof. Thereafter, laborers entered the furnace after it had cooled sufliciently, and with sledge hammers, picks, crowbars, and chisels, broke out a suihcient number of bricks to allow the entire furnace lining to be pried away from the shell and to fall on .the water-cooled plate. The loosening of the lining in this manner is diflicult because the heat of operation of the furnaces fuses the bricks of the lining together and converts them into an essentially monolithic structure. Removal of the lining is particularly clifllcult in the vicinity of the tapping spout, where the bricks are bound by metal and slag adhering thereto. After the entire lining has been deposited on the metalplate at the bottom of thefurnace, the furnace is tilted and the loose brick removed therefrom by hand and shovel thrown into a debris-carrying device, such as an old ladle placed in the back of the furnace.

The present invention dispenses to a large extent with the manual operations heretofore necessary for the loosening and removal of the furnace lining. In the practice of the invention a. plurality of metal inserts are placed in the furnace lining at points spaced substantially equally thereabout. Such inserts are adapted to be pulled out by a crane and have suflicienten- 'gagement with the furnace lining so' that when they are lifted they carry with them, at least for a short distance, a substantial portion of the furnace lining, thereby breaking it free from adjoining portions of the lining and allowing it to fall into the hearth of the furnace. Preferably the portion of the insert which directly imposes the lifting force upon the lining is of such size horizontal position, allowing it to be caught read.-

ily in a debris box or the like, an operation which would be more diflicult if the loosened lining were to fall vertically and in vertical position down the side of the lower retained lining.

In the modification shown, such inserts are of two types, the first of which, shown in Figures 3 and 4, is designated the small insert or pullout plate. Such insert consists of a vertical plate portion 34 having a portion of an L-shaped angle iron 36 welded to the bottom thereof as shown, and a hole 38 in the top thereof for the reception of lifting means. The second type of insert, which is called the large insert or pull-out plate, is shown in Figures 5 and 6. Such insert consists of a vertical plate 40 curved to conform to the furnace shell and having at the bottom thereof two short pieces of L angle bars 42 welded thereto as shown. The central bottom portion of plate 40 is cut away at 44 to provide for the tap hole. The top of plate 40 is provided with two holes 48 for the reception of. the lifting means.

The inserts are placed in the furnace shell, as shown, before the lining is laid, with the elongated vertical portion thereof in contact with the shell and with the L-shaped bars at the bottom thereof resting upon the top of the top supporting hearth brick 22 so that the projecting leg of the L bar extends toward the interior of the furnace. This leg, which directly sustains the weight of the lining to be loosened when the insert is lifted, is made of a length substantially less than the thickness of the lining at that point, both to protect it from the furnace heat'and to cause the loosened lining to fall in the preferred manner above described. The furnace lining is then laid in the conventional manner, portions of the bricks contacting the inserts being cut away, if necessary, to receive the inserts so as to allow the inner hearth side of the lining at the inserts to conform to the remainder of the smooth interior surface thereof. The

vertical portions

34 and 40 of the inserts are made of such height that they are completely covered by the lining brick.

When the furnace so provided with inserts in the lining thereof has been operated for such a time that the lining needs renewal, the furnace roof and electrodes are removed as formerly, a water-cooled plate 41 is inserted in the furnace to cover the bottom thereof, and, after the furnace has cooled sufliciently, men working from outside on ladders or scaifolding manually dislodge the bricks over the

holes

38 and 36 in the inserts. The location of such holes can readily be ascertained if the inserts are put in in certain known locations with respect to fixed structures on the furnace, such as the doors and spout. When the holes in the inserts have been uncovered, a debris box 48, having an outer contour conforming to the inner surface of the lining, is placed within the furnace, as by a crane equipped with the chain and sling shown in Figure 2, in a position beneath the lining and centrally located with respect to the insert which is to be pulled. The debris box may rest on plate M as shown, the chain and sling being then disconnected therefrom until the box must be moved or emptied.

A suitable lifting means, such as a crane hook, is then engaged in the hole in the particular insert to be pulled and the insert is pulled upwardly, or upwardly and slightly inwardly, of the furnace. The engagement of the insert, particularly by reason of the engagement of the projecting leg on the L-shaped bottom thereof with the furnace lining, is suflicient to carry a large portion of such lining upwardly with it and thus to break it free from the furnace shell and from the adjoining portions of the lining. By reason of the fact that the projecting leg of the L-shaped' bottom of the insert in the preferred embodiment engages only the edge of the lining to be loosened adjacent the furnace shell, a substantially vertical lifting of the insert has the effect of causing the loosened lining in general to pivot about its lower edge adjacent the hearth and to fall into the debris box insubstantially horizontal position. In Figure 2 the lower edge about which the loosened linin pivots on the top supporting hearth brick 22 at the right of the furnace section is designated 52 and that at the left of the furnace section, where the thicker bottom lining is employed is designated 50. It will be understood that, since the lining is composed of individual bricks held together by a bonding material, sometimes the break between the linin to be retained, that is, the top supporting hearth brick, and the lining to be removed, especially at points somewhat distant from the inserts, takes place at levels somewhat different from that of edges 50 and 52. In some cases, furthermore, pulling of the inserts may cause a general collapse of the lining rather than the removal of substantial sections by causing them to pivot as a whole, Usually, however, the parts of the lining to be removed remain bonded together firmly enough be lifted and pivoted as a whole in the manner describ iiga especially in, the vicinity of the inserts. e portion of the lining thus broken free falls inwardly of the furnace, and when the debris box is properly located the greater part of the liningfalls within it. The debris box is then emptied and placed adjacent another portion of the furnace lining which is to be removed in the same manner as above. This operation is repeated, usually at successive inserts around the furnace, until all the inserts have been pulled, and then any lining remaining, which may be in the nature of a shallow layer on portions of the top supporting hearth brick 22 between the points at which the inserts were located, may be removed by hand. The furnace is then relined as formerly, with the modification, however, that the inserts, which are substantially unharmed by repeated use, due to their being enclosed in the refractory, are cleaned and then inserted in the furnace, as described, before application of the lining.

It will be apparent that the invention makes possible the saving of considerable time in the removal of an old lining from a furnace and its replacement by anew lining, On the average, use of the invention allows such operation to be completed on a furnace of the type shown with the saving of eight hours in the total idle period of the furnace. In addition, it makes possible the saving of a large amount of disagreeable labor. since workmen must be within the hearth of the furnace during the lining removing operation only for. the purpose of removing the few small portions of the lining remaining after pulling the inserts.

Having thus fully disclosed the method and apparatus for the present invention, I claim as new the following.

I claim:

ii. In a furnace comprising a shell and a reiractcry lining, a plurality of metal inserts of generally L-shape, said inserts being of substantial area, one leg of the inserts being mounted in upright position between the shell and. the lining and the other projecting outwardly from the shell under a portion of the lining, said inserts bein spaceclnat intervals around the furnace, whereby pulling of the inserts in a direction upwardly of the furnace effects dislodeement of the furnace lining,

2. In a furnace comprising a shell and a rattletory lining, a plurality of metal inserts of sonerally L-shape, said inserts being of substantial area, one leg of the inserts being mounted in upright position between the shell and the lining and the other projecting outwardly from the shell under a portion of the lining, said inserts being spaced at approximately uniformintervals around the furnaces, said inserts having means at the upper end of the leg between the furnace shell and the lining for the attachment of a lifting means for pulling the inserts upwardly to effect disiodgement of substantially all the lining.

3. In a furnace comprising a vertical furnace shell and a horizontal refractory support or annular shape disposed therein and lying adjacent the inner periphery of the shell, and a refractory lining resting on top of the support and against the shell, at least one metal insert oi generally L-shape, said insert being of substantial area, one leg of the insert being mounted in upright position between the shell and the lining and the other projecting outwardly from the shell under the edge of the lining and being of substantially less length radially of the furnace than the thickness of the lining, said insert having means at ihe upper end of the leg between the furnace shell and the linin for the attachment of a lifting; means for pulling the inserts upwardly whereby the portion of the lining in the vicinity of the insert is broken loose from the shell, support, and adjacent portions of the lining, pivots about the bottom edge thereof and falls inwardly.

1. In the furnace set out in class. a plural of said inserts spaced at intervals eroul l furnace, whereby pulling of the inserts vet r effects dislodgement oi substantiailyeli nace lining.

STANLEY A. ZZUM'OROWSKI.

(CEFa GETEE) The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 517,939 Stickney Apr. 16, 1,645,011 Kinney Oct. ll, 1927 1,868,352 Foltz July 29, 1932