US2174927A - Apparatus for heat treating furnace linings - Google Patents

Description

Oct. 3, 1939.

w. E. MOORE El AL APPARATUS FOR HEAT TREATING FURNACE LININGS 3 Sheds-Sheet 1 Filed Sept. 9, 1938 M, R\\ k N a. aw mm. 3 mm mum mm v ww a W mm 0% MM av M @N W QM N. NM. @N MN. MN ON m INVENTORS l5. Maore W' .B. Wallis YM MFM Oct. 3, 1939. w. E. MOORE in" AL APPARATUS FOR HEAT TREATING FURNACE LININGS Filed Sept. 9, 1958 5 Sheets-Sheet 2 INVENTORS WllllmmE.M0are VViZZiamli. Wallis 7m mrp c HTTORNEYS Oct. 3, 1939. w. E. MOORE ET AL 2,174,927

APPARATUS FOR HEAT TREATING FURNACE LININGS Filed Sept. 9, 1938 s Sheets-Sheet 5 :m (Y: Q N 0' B m \D 1 N INVENTOR 5 William 1? Moore Wflliamfl Wallis m, P Iv-14.

HTTORNEYS Patented Oct. 3, 1939 UNITED STATES PATENT OFFICE APPARATUS FOR HEAT TREATING FURNACE LININGS Application September 9, 1938, Serial No. 229,106

12 Claims.

Our inventionrelates in general to refractory furnace linings and to apparatus for heat treating them, and more particularly to apparatus for burning in and repairing the refractory linings of furnaces and like structures.

Furnaces such as are used for melting, refining or treating metals, glass, or the like, or furnaces for boilers and the like are subject to relatively high temperatures and are usually constructed with highly refractory linings. These linings are commonly made from firebrick aggregates of silica or magnesite sand and the like, cemented or bonded together by a binder, such as, for example, fireclay or hydrocarbons and similar substances. The fusing or maturing point of the binders employed is much lower than that of the refractory material from which the linings and particularly the bottoms, are formed, and the use of such a binder impairs the effectiveness of the refractory material in direct proportion to the amount of binder used, as it renders the furnace linings more readily fusible at lower temperatures and more susceptible to disintegration. In the repairs to the linings of such furnaces, refractory substances with a binding material such as we mentioned, are usually employed and are subject to the same objections.

It is also desirable that the lining have as dense and as homogenous a surface as possible, so that the content of the furnace, such as molten metal, may not find its way into the body of the lining as the deterioration of the lining depends upon the extent of surface exposed to the corrosive action of the molten charge and the more porous the lining, the greater is the surface exposed. It is, therefore, a great advantage to fuse into a homogenous whole the lining of the furnace, and particularly those parts which come into contact with highly heated metals or highly heated or corrosive products of combustion and to fuse such portions without the use of binders or fluxes which will impair the resistance of the lining material to high temperatures and corrosion.

Hvretofore, attempts have been made to burn in the bottoms of electric furnaces having highly refractory bottoms made from materials, such as magnesite, by means of the ordinary electric arc which is generally set up to are against a delta or T made of carbon electrodes placed across the bottom. While this plan may have some advantages for small furnaces, it becomes less practical as the size of the furnace increases and, even with small furnaces, it has heretofore been essential to reduce the melting temperature of a highly refractory material, such as magnesite, by adding to it a flux such as 8 to 10% of open hearth slag or silica, etc. The same difficulty applies to the refractory bottoms and linings in open hearth furnaces and the like, as the heat is not available there from combustion of fuel to burn in highly refractory bottoms. Even with such heat as is available, great damage resulting from the overheating thereof is usually done to the roof and other parts of the refractory lining of the furnace when burning in the bottom so that in open hearth furnaces the life of the refractory lining is still further sacrificed by fluxing it more liberally, so that the lining may be burned in at a lower temperature.

The most desirable condition, for example, in a metal melting furnace bottom and lining exposed to the action of molten metals and slag, is to have the exposed layers thereof thoroughly fused together' into a vitreous mass without the use of fluxes or binders. Our apparatus enables this to be done. The heat-resisting properties of the refractory material need not therefore be impaired by adulteration with fluxes, and we have found that linings made according to our invention very successfully resist the dissolving action of slag and the boiling action of molten metal and like sources of lining deterioration.

The electric arc has a temperature sufficiently high to melt any known refractory material if the are be concentrated or blown directly against the material. We have provided an' apparatus which utilizes the properties of the electric are for burning in or fusing the refractory linings, particularly the bottoms, banks or side walls, on all kinds of furnaces, electric, open hearth, or other kinds, but without overheating of other parts of the furnace structure. Furthermore, it is thus possible to provide a lining which is made from unfluxed refractory material which may be formed in situ and fused to the shape of the furnace or like structure. The refractory ma-, terial may be preformed, if desired, or a loose or granular material of any size particle may be employed, such as granular magnesite. Our device consists of a portable apparatus having supports for two electrodes of suitable material, such as carbon or graphite inclinably mounted like a V with the arcing points at the bottom of the V. By means of this arrangement, the arc may be blown or repelled vigorously by magnetic repulsion away from the bottom of the V and may be directed against the material to be fused or sintered in. The device is portable and is arranged for manipulation of the electrodes to difierent positions so that the arc may be brought to bear on any desired part of the furnace lining and thus fuse the refractory material progressively until the desired. portions of the furnace lining are covered with a vitreous mass or to use the expression of the industry burned in.

By our invention, we provide a simple and convenient arrangement whereby an electric arc can be maintained between the electrodes of a portable apparatus which can be readily manipulated so that the heattherefrom may be directed against any desired point. 1

This application is a continuation in part 01' our copenoling application for United States Letters Patent, Serial No. 98,918, filed September view along the section IV--IV of Figure 2;

Figure 5 is a plan view of the electrode end of.

the apparatus; I

Figure 6 is an elevation of the outer end of the control end of the apparatus; Figures 7, 8 and 9 are detail views oi portions of the apparatus.

In the drawings, we have shown in Figure 1 a portable water-cooled electric torch T made according to our invention in position to burn in the bottom B of furnace F. It is to be understood that the apparatus is suitable not only for burning in the refractory bottom but by proper manipulation other parts of the refractory lining may be treated.

The torch consists of two electrode holders l0, preferably made of copper, each mounted on an electrode carrying member or arm H. Each of the electrode arms I is slidably and rotatably mounted within a copper contact sleeve i2, to which a suitable terminal l3 for the electric power supply is attached. Adjacent the holder end of the arms II is a spacing member l4 preferably formed of metal and having ends which embrace an insulating sleeve i5, each sleeve surrounding the arm II in such manner that each of the arms H may be rotated within its asso ciated insulating sleeve. To the outer end of the electrode arms Ii, that is the end distant from the electrode holders I0, suitable manipulating handles I6 are secured. By means of these handles, which are made of insulating material such as wood, fibre, or synthetic resin, etc., the electrode arms can be moved longitudinally and rotated, and the apparatus as a whole can be manipulated. Fixedly mounted on each electrode arm ll, between the handle I and contact sleeve i2 is a rock crank II. The cranks I! (see Figure 4) are swivelly connected by an insulating connecting link l8, preferably made of Bakelite, fibre, or other physically strong insulating material, so that when one electrode arm is rotated in one direction, the other electrode arm will move simultaneously in the opposite direction and in the same amount. The ends of the electrode arms adjacent the handles i6 are rotatably secured together in spaced relation by a spacing link l9 of insulating material.

' The electrode arm II is preferably made from hollow copper tubing and is attached to the electrode holder ill in any suitable manner, as, for example, by screw threading. The electrode holder ID has an internal water passage 20 substantially therearoundandto one end of this water passage a pipe 2| is attached. The pipe 2| is smaller in diameter than the inside diameter of the electrode arm II, and passes therethrough, so that there is an annular space between the pipe 2| and the inner wall of arm into which space the other end of passage 20 leads. Pipe 2| extends through the disc 22 which closes the handle end of the electrode arm II and has a connection 23 to a suitable source of water supply (not shown). An outlet 24 is provided in the outer end of arm ll. Cooling water may thus be passed through pipe 2| around passage 28 in holder I0, back through the annular space between the electrode arm II and tube 2| and.

discharged through the discharge connection or outlet 24.

The contact sleeves I2 are each mounted against movement within an insulating sleeve 25, which sleeve is secured in a spacing member or support 26. The spacing member 26 (see Figure 3) consists of an upper clamping portion 21 and a lower clamping portion 28, removably secured together. The ends of both of these portions are shaped to embrace and retain insulating sleeve in a predetermined position. A lifting hook 29 is secured to the arm spacing member 26. The lower portion 28 has a rear-wardly projecting horizontal arm 30 and a downwardly projecting bifurcated portion 3| whichis plvotally secured by a bolt 32 to the head 33 of a hollow screwthreaded upright or support 34, which is adjustably secured to the movable truck 35.

The truck 35 has two front wheels 36 and a swivel wheel 31 at the rear which supports a framework 38 through which the hollow upright 34 projects and is supported on the frame 38 by the adjusting nut 39, which is in anti-friction engagement therewith. By manipulation of the nut 39, the electrode arms may be adjusted to the desired vertical position. A suitable counterweight 40 may be placed, if necessary, on frame 38 to resist the turning movement due to the counter-balance device hereinafter to be described.

In order to counter-balance the weight 01' the electrode holders and electrodes 50 that the apparatus may be readily worked by man power, we provide 'a counter-balance device. This device (see Figures 1 and 8) consists of a balance arm 4| having an upwardly inclined reduced end portion which is received in an opening 42 in the supporting member 34. The balance arm 4| has a number of holes 43 at spaced intervals along its length into any one of which one end of a suitable, tension spring 44 may be secured. The other end of the spring 44 is fastened to a hook member 45 which, in turn, is attached to the horizontalarm 3|) by an adjustable screw-threaded connection 46. By hooking one end of the spring 44 in a suitable hole in the balance arm 4|, and connecting the other end to the hook member 45, which, in turn, is secured in a suitable position to the projecting arm 30, and by adjusting the connection 46, the proper counter-balancing force may be secured. In some installations,

counter-balancing may be secured by means oi suitably insulated counterweights (not shown) connected to arms I I.

When placing the apparatus in position and at other times during the operation of the apparatus, it may be desirable to move the torch itself and the truck 35 as a unit. To prevent the torch T from swinging "in a horizontal plane with respect to the truck 35, we provide a lock member or latch. 41 which is pivotally secured to the bifurcated portion 3| of the spacing member 26 so that when the torch T is to be locked to the truck 35, the latch 41 will be in the perpendicular position shown in Figures 1, 2 and 9, where the depending portion of. the latch is received in the latching groove 48 formed in the framework 38. Swivelly secured to the latch 41 is a hook 49, which when connected to the spacing member 26 will hold the latch 41 out of locking engagement with the groove 48 and thus permit the torch T to freely swivel on the truck 35. In Figure 2, the latch 41 is shown in dotted lines out of locking engagement.

The electrodes 50 of a proper size and formed from a suitable material such as carbon or graphite, are secured in the electrode holder or clamp III by any suitable means such as clamping wedges 5|, preferably made of copper, which are driven in from the upper side of the holder H].

To prevent the electrode arms II from sliding too far along the contact sleeve l2, we provide on each electrode arm II a clamp or stop 52 which is secured in position by the bolt 53.

Operation of the apparatus A layer of refractory material is rammed in on the elementary bottom layers of the furnace lining which are usually of brick. The electrode end of the torch is projected through a door or other suitable opening into the furnace and the water cooling circulation is established through connections 23 and 24. An arc is then struck by, rocking the arms H by means of the handles l6 until the tips of the electrodes 50 contact, after which they are rocked back slightly to draw the arc to the desired length, whereupon the free-burning arc is blown or projected against the lining at the desired point until the refractory lining is burned in or sintered. The are is then moved from place to place on the lining until the desired area is burned in or sintered. Due to the construction of the torch, the arms may be moved backwards or forward, tilted and rotated, and the truck may be manipulated so that all the desired area of. the furnace lining may be processed.

It is also possible to disconnect the torch from the truck by removing the bolt 32. The torch may then be suspended by means of the hook 29 from an overhead crane or the like, or from a convenient part of the structure to be treated, in which circumstances, the electrode end of the torch T may be inserted into the furnace by first removing the roof or it may be introduced through any other convenient opening. In case the torch is supended from a convenient support, the clamps 52 may be adjusted in position along the arms, so that sliding movement of the arms in the contact sleeves 2| will be restricted. Many modern furnaces, especially electric furnaces, are of the tilting type and have removable roofs and the overhead suspension of the torch is particularly applicable when treating such furnaces.

It will be observed that we have invented a convenient and wholly satisfactory apparatus for heat treating the refractory lining of any type of furnace and which may be used for heat treating the refractory linings of other'vessels, such as ladles, launders, spouts, etc. Linings so prepared and treated show pronounced economies and advantages in furnace operation. By our invention, not only can new linings be satisfactorily treated, but repairs can be expeditiously made to defective linings. Furthermore, the desirable refractory material may be burned in or fused without the use of fluxes, thus retaining unimpaired the maximum refractory and other desirable qualities of the lining.

While we have illustrated and described certain preferred embodiments of. our invention, it will be understood that the invention is not limited thereto and that various changes in the shape, size and arrangement of parts may be resorted to without departing from the spirit of our invention or the scope of the following claims.

We claim:

1. An electric arc device for burning in furnace linings by the application of heat to selected areas of the interior of the furnace comprising a mobile support, a pair of holders in the support, a long slender electrode-carrying arm passing through each holder and slidable back and forth therein, an electrode on one end of each arm with its axis extending in a generally crosswise direction to the longitudinal axis of the arm, and means connecting the arms to enable them to be moved back and forth in unison.

2. An electric arc device for burning in furnace linings by the application of heat to selected areas of the interior of the furnace comprising a mobile support, a pair of holders in the support, a long slender electrode-carrying arm passing through each holder and slidable back and forth therein, an electrode on one end of each arm with its axis extending in a generally crosswise direction to the longitudinal axis of the arm, means connecting the arms to enable them to be moved back and forth in unison, and means for insulating the arms from each other and from the support, said arms being formed of conducting material, and means for connecting said arms to opposite sides of an electric supply line.

3. An electric arc device for burning in furnace linings by the application of heat to selected areas of the interior of the furnace comprising a mobile support, a pair of holders in the support, a long slender electrode-carrying arm passing through earh holder and slidable back and forth therein, an electrode on one end of each arm with its axis extending in a generally crosswise direction to the longitudinal axis of the arm, and means for simultaneously moving the electrodes toward and away from each other.

4. An electric arc device for burning in furnace linings by the application of heat to selected areas of the interior of the furnace comprising a mobile support, a pair of holders in the support, a long slender electrode-carrying arm passing through each holder and slidable back and forth therein, an electrode on one end of each arm with its axis extending in a generally crosswise direction to the longitudinal axis of the arm, means connecting the armsto enable them to be moved back and forth in unison, said mobile support including a carrier in which the holders are mounted, and a carriage on which the carrier is mounted for universal movement.

5. An electric arc device for burning in furnace linings by the application of heat'to se lected areas'of the interior of the furnace comprising a mobile support, a pair of holders in the support, a long slender electrode-carrying arm passing through each holder and slidable back and forth therein, an electrode on one end of each arm with its axis extending in a generally crosswise direction to the longitudinal axis of the arm, means connecting the arms to enable them to be moved back and forth in unison, said mobile support comprising a wheeled carriage, a vertically adjustable stand on the carriage, and a carrier in which said holders are mounted on. the stand, the stand being swiveled on the carriage and the carrier being tiltably mounted on the stand whereby a universally adjustable sup= port is provided for said carrier, said support enabling the unit as a whole to be moved back and forth with relation to the furnace lining being treated, the slide support for said arms enabling the electrodes to be moved back and forth rela= tively to the carriage and the universal mountings enabling the electrodes to be entered in the furnace at the desired angle.

6. An electric arc device for burning in furnace linings by the application of heat to selected areas of the interior of the furnace comprising a mobile support, a pair of holders in the sup port, a long slender electrode-carrying arm passing through each holder and slidable back and forth therein, an electrode on one end of each arm with its axis extending in a generally crosswise direction to the longitudinal axis of the arm, means connecting the arms to enable them to be moved back and forth in unison, said arms being relatively long with respect to the size of the mobile support whereby they may be project ed to a great length into the interior of the furnace being treated, said holders being tiltably mounted on the support, and means for counterbalancing the projectingends of the arms.

7. An electric arc device for burning in furnace linings by the application of heat to selected areas of the interior of the furnace comprising a mobile support, a pair of holders in the support,

, ed on the support, and means for counterbalanc-=.

ing the projecting ends of the arms, said counterbalancing means comprising a spring connecting the holders with the support.

8. An electric arc device for burning in furnace linings by the application of heat to selected local areas of the interior of the furnace compris ing a mobile support, a pair of holders in the support, a long slender electrode-carrying arm passing through each holder and slidable back and forth therein, said arms being parallel, an electrode on the end of each arm with the axis of the electrode crosswise of the axis of the arm, said arms also being rotatable in their holders, and means connecting the two arms for transmitting rotary and longitudinal movement from m one to the other.

9. An electric arc device for burning in furnace linings by the application of heat to selected local areas of the interior of the furnace comprising a mobile support, a pair of holders in the support, a long slender electrode-carrying arm passing through each holder and slidable back and forth therein, said arms being parallel, an electrode on the end of each arm with the axis of the electrode crosswise of the axis of the arm, said arms also being rotatable in their holders, means connecting the two arms for transmitting rotary and longitudinal movement from one to the other, and means for adjusting said holders vertically relatively to the support.

10. An electric arc device for burning in furnace linings by the application of heat to selected local areas of the interior of the furnace comprising a mobile support, a pair of holders in the support, along slender electrode-carrying arm passing through each holder and slidable back and forth therein, said arms being parallel, an electrode on the end of each arm with the axis of the electrode crosswise of the axis of the arm, said arms also being rotatable in their holders, means connecting the two arms for transmitting rotary and longitudinal movement from one to the other, means for, adjusting said holders vertically relatively to the support, and rotatable means for carrying the holders on the support to enable the arms to be adjusted angularly with reference to a horizontal plane.

11. An electric arc device for burning in furnace linings by the application of heat to selected local areas of the interior of the furnace comprising a mobile support, a pair of holders in the support, a long slender electrode-carrying arm passing through each holder and slidable back and forth therein, said arms being parallel, an electrode on the end of each arm with the axis of the electrode crosswise of the axis of the arm, said arms also being rotatable in their holders,

means connecting the two arms for transmitting rotary and longitudinal movement from one to the other, means for adjusting said holders vertically relatively to the support, and rotatable means for carrying the holders on the support to enable the arms to be adjusted angularly with reference to a horizontal plane, said vertically adjustable means also providing a swiveled mounting for the holders on the support whereby the longitudinal axis of the arms may be adjusted relatively to the longitudinal axis of the support.

12. An electric arc device for burning in furnace linings by the application of heat to selected local areas of the interior of the furnace comprising a mobile support, a pair of holders in the support, a. long slender electrode-carrying arm passing through each holder and slidable back and forth therein, said arms being parallel, an electrode on the end'of each arm with the axis of the electrode crosswise of the axis of the arm, said arms also being rotatable in their holders, and means connecting the two arms for transmitting rotary'and longitudinal movement from one to the other, said holders each comprising an insulating block with a conducting sleeve therein, each sleeve having-an electric lead wire attached thereto, the arms being of metal, said conducting sleeves providing a sliding contact for connecting the electrodes with a source of current.

WILLIAM E. MOORE. WILLIAM B. WALLIS.

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