US2301855A - Method and apparatus for removing fire rings from rotary kilns - Google Patents

Description

Nov. 10, 1942. w c E 2,301,855 METHOD AND APPARATUS FOR REMOVING FIRERINGS FROM ROTARY KILNS Filed June 4, 1941 2 Sheets-Sheet l Nov. 10, 1942'.

Filed June 4, 1941 W R. CLIFFE METHOD AND APPARATUS FbR REMQVING FIRE RINGS FROM ROTARY KILNS 2 Sheets-Sheet 2 11M)? mm;

and down a given UNHTED STAT METHOD AND APPARATUS FOR REMOVING FIRE RINGS FROM ROTARY KILNS WalterB... Clifie, Hershey, Pa., assignor of onehalf to Cardox Corporation, Chicago, 111., a corporation of Illinois Application June 4, 1941, Serial No. 396,632

12 Claims. (or. 263-32) This invention relates to new and useful improvements in methods and apparatus for removing fire rings from rotary kilns employed in the production of such materials as. lime, magnesite, refractory dolomite, or the like; and in.

any processes employing rotary kilns in connection with which the removal of fire rings:is a

problem.

Although certain differences will be found in the character, location, etc, of the fire rings; which are formed in rotary kilns employed in different processes, these differences are immaterial insofar as carrying out the steps of the present method and making use of the present apparatus is concerned. For that reason itis believed to bejsuficient to only describe the present invention in connection with its application to the removal of fire rings from rotary lime kilns and it will be understood that the description is intended to embrace the removal of fire rings from rotary kilns employed in all other analogous processes.

As a typical example, let us consider a rotary cylinder lime kiln which is 290 feet long. and 7 feet 5 inches in diameter. such an inclined cylinder will be of an inch in thickness and will have applied to the interior thereof a 7 inch lining which is usually formed of bricks made from suitable refractory material. This lining will leave a bore or inner chamber which is 6 feet 9 inches in diameter.

During normal operation of such akiln, pulvercarbonate are delivered to the cylinder as it is rotated. The burningof the fuel accomplishes disassociation of the calcium carbonate and the resultant lime is spilled at the discharge point of the kiln.

The fire ring, which is formed by the accumulation of slag on the brick lining, makes its ap- The steel shell of Y the method to be employed forrendering the kiln suitable for further use. It is the present practice ized coal, or some other suitable fuel, and calcium pearance any time after the burning infof the kiln. The ring may cover from 2 to approximately 10 feet of the length of the kiln. Its location may vary considerably in different kilns and accumulation of the slag fire ring and lowering of. the efficiency of the kiln can be permitted to continue until the ring nearly bridges or closes the bore through the cylinder at which time it be.-

comes necessary to reach a decision regarding 55 tudinally of the kiln and its great mass renders to either shut down the kiln temporarily while an attempt is made ,to enlarge the opening in the formation to a sufficient extent to permit the operation to be resumed or the kiln must be completely burned out and removed from the production line. In either case, the feeding of fuel and material is stopped.

If the operator of the kiln is confronted with a pressing need for production, he will probably decideto shut down the kiln temporarily while an attempt is made to enlarge the opening in the fire ring formation. If the fire ring has formed relatively close to the dischargeend of the kiln, the operator may employ either alarge water cooled boring tool or a huge water cooled poker; If thejboring tool is selected, it is adjusted with respect to the formation and the kiln is rotated while the tool makes the desired cut. The slagformation may be cut away to a desired depth in this manner. The total loss of operating time for this type of removal usually amounts to about six hours. However, the product iscontaminated with fine cuttings from the formation and a high quality product may not be obtainable for many additional hours.

If. the hugewater poker is the selected implement, the kiln is stopped and the poker is manipulated by the ten or twelve men requiredto handle the same. The function of the poker is to chip or break away the inner portion of the ring. This. method of removal of the inner portion of the formation, to enlarge the hole through said formation, also requires about five or six hours but it is the least desirable of the several methods employed at the present time. .This is due to the fact that the treatment is very injurious to the refractory lining and the water from the poker has a ruinous effect on numerous products.

Probably the preferred method for partial fire ring removal involves the use of a kiln gun which fires slugs, weighing as much as five ounces, into the formation. It is the function of this gun to direct the slugsso that the top or high points of the formation are trimmed down and the opening is, thereby, enlarged. This method of partial removal has very definitaunavoidable limitations which may be noted as follows:

It usually requires in the neighborhoodof 1000 shells to remove a sufficient amount of the slag formation to render the kiln suitable for further use. As the slag formation ages, it grows longithe kiln gun entirely ineffective. When this point is reached, a complete shut down is necessary. The shattering effect of the slugs on the slag formation has a tendency to pulverize the material which in some cases causes the kiln charge to be contaminated, thereby considerably reducing its value.

If either of the above noted methods of partial slag removal is employed. for keeping a kiln in operation, regular trimmings have been found to be the best practice. This will be obvious when it is considered that if the fire ring is allowed to build up to too great a thickness, the charge impounded behind the ring will fiush forward in uncontrolled quantities when the ring is trimmed down. Th product obtained in this manner is of questionable quality and it often must be wasted.

If the operator decides to burn out and take the kiln off the production line, the feed of fuel and material is usually stopped and rotation of the kiln is continued for a period of four or five hours to permit the charge to be rotated therefrom." Of course, that portion of the charge which remains impounded behind the fire ring will not be discharged during this period. Only approximately 20% of the charge obtained during this period can be considered as a usable product.

It ordinarily requires a minimum of twentyfour hours before men can enter the kiln to attempt to remove the slag after all obtainable material has been drawn off. It requires very rapid chilling of the kiln to permit men to enter the same in this minimum period of twenty-four hours and this rapid chilling invariably adversely affects the lining. It usually is discovered that only the surface of the slag is really cool enough to be worked after such a short chilling period. When this apparently cool surface is removed, a red hot interior usually is encountered. The 'work of removing slag under these conditions is extremely difficult and men can only stand Very short shifts. It is not unusual in an old formation to remove as much as thirty tons of slag and from eight to ten hours invariably are required for this phase of the shut down.

When the kiln is returned to the production line, it must pass through the fire up period. With comparatively new installations, not many hours are required before quality of production is resumed. However, in the older plants several days often are required to regain a state of balance. It, of cource, is necessary to reheat the lining after such a slag removal operation. Maintenance costs for the refractory linings can be rendered extremely high if rapid reheating of the lining is resorted to. This is due to the fact that the lining may have taken on surprising quantities of moisture as a result of the length of the shut down period and prevailing atmospheric conditions.

With equipment which is in good condition and with an efficient organization, it is possible to accomplishthe above referred to cycle of slag removal in approximately forty-eight to seventytwo hours. As the operating value of the average rotary kiln is usually calculated to be from twenty-five dollars to fifty dollars per hour and as slag formation is such a serious factor in some kilns that shut downs every eight to fourteen days are considered necessary, it is not difficult to estimate the loss in operating value which confronts the management of this type of equipment.

It is the primary object of this invention to provide a method and apparatus for completely removing fire rings from rotary kilns without having to burn out the charge or shut down for a chilling off period to enable men to enter the kiln, whereby damage to the refractory lining is avoided and a great saving in operating time is effected.

A still further important object of the invention is to provide a method and apparatus for removing the entire fire ring from a rotary kiln by breaking the slag into large chunks which can be discharged by rotating the cylinder with the result that serious contamination of the product is avoided.

A more specific object of the invention is the provision of apparatus of the above mentioned character which is manipulated by workmen operating at the side of the kiln, in the vicinity of the fire ring, whereby the breaking up of tho fire ring into large chunks and the complete severance of the same from the refractory lining may be accomplished within a very few minutes after rotation of the cylinder has been stopped.

Other objects and advantages of the invention will be apparent during the course of the following description.

In the accompanying drawings forming a part of this specification and in which like numerals are employed to designate like parts throughout the same,

Figure l is a fragmentary side elevational view of a rotary kiln at the location of a fire ring and with a portion of the apparatus of this invention properly applied thereto,

Figure 2 is a vertical sectional View taken on line 2-2 of Fig. l but discloses the kiln cylinder as having been rotated approximately 45 so that the remainder of the apparatus of this invention may be applied thereto and properly positioned for performing its intended operation.

Figure 3 is a fragmentary, enlarged, vertical sectional View taken on the plane of the section shown in Fig. 2 and illustrating a complete operative assembly of the fire ring removing apparatus embodying this invention,

Figure l is a detail perspective View of a refractory lining retaining block,

Figure 5 is a detail perspective view of an anchoring device for the block of Fig. 4,

Figure 6 is a detail elevational view of a carbon dioxide cartridge clamping device which forms a part of the apparatus embodying this invention, and

Figure 7 is a detail elevational vi w of a detachable handle which is applied to a carbon dioxide. cartridge to facilitate manipulation of the latter.

In the drawings, wherein for the purpose of illustration are shown the preferred embodiments of this invention, and first particularly referring to Figs 1 to 3 inclusive, the reference character it designates the steel shell of the rotatably supported kiln cylinder. As this invention is only concerned with the removal of the fire ring H which has formed in the bore of the cylinder, the portion of the length of the cylinder which contains the fire ring is all that has been illustrated. A refractory lining E2, of suitable thickness, is conventionally applied to the interior of the shell or cylinder Hi. This refractory lining is usually formed of bricks but no attempt has been made in the aforementioned figures to specifically illustrate this particular type of lining construction. This refractory lining must be replaced many times during the working life of a kiln and, of course; the kiln must be completely disclosure of the apparatus given in the drawings is an installation of that character. It is possible, however; to install the permanent portion of the apparatus in a kiln which is provided with a lining which is in entirely satisfactory condition and, for that reason, is not ready to be replaced. The slight structural variations required to install the apparatus on a kiln which is provided with a lining will be explained as the deextends a few inches into the lining,=it will-serve as a suitable anchor for the latter; With the lining anchored in this way i at the several ports,

formed in this manner, the remainder of the lining can be cut through at each of these ports by working through the bores of the sleeves or pipesections. By exercising a reasonable amount consideredas involving approximatelya ten to 'twenty foot portion of the kiln interior.

While the kiln is shut down for the installatio of a new lining, four rows of holes l3 are cut in the steel shell or cylinder 10. Theserows of holes are equally spaced around the periphery of the shell and the holes of each row may be located with from two to threefoot centers. Each hole need only. be approximatelythree inches in diameter. Fig. 1 discloses four such holesin each row. It is to be understood, however, that a greater or lesser number may be provided, if desired. i i i Fig.5 discloses an anchor member M. This anchor may either be formed in one piece, as shown, or three separate pieces may be provided. This anchor is attached, as by welding, to the inner surface ofthe shell or cylinder I0 so as to surround a hole or port l3. One of these anchors is provided for each one of these ports. The two parallel sides of the anchor are intended to extend longitudinally of the cylinder. The

third side extends circumferentially and is placed on the down-slope side of its port, as is clearly illustrated in Fig. 1. i

This anchor M is employed for holding in place i the block I5, which is disclosed in detail inFig. 4.

This block is formed of two ordinary kiln liner bricks Ma and I5!) which are cored to-provide the opening IS therethrough. This two part block may be slipped into the anchor I i through the open, up-slope side of the same. After the several anchors l4 and blocks l5 are properly positioned, the refractory lining 12 may be constructed. The several blocks l5 perform the very im portant function of holding or retaining the line ing against circumferential shifting. The core portions it of the several blocks [5 areintended to register with the ports or openings 83 formed in the shell or cylinder l8. These cores it and the ports l3 provide passages from the exterior of the shell or cylinder H] to the interior of the lining i2. aa 7 a If an installation is to be made in a kiln which is already provided with. a refractory lining, the

installation of retaining means for the lining can extending the ports or openings partly through the refractory lining. Ametal sleeveor section of pipe then may be inserted through each port and the part'iallyformed hole in the lining and Welded in place. If this sleeve or pipe section of care in extending these holes through the lining, no damage to the latter will result.

Each port I3 is then provided with an exterior reinforcing plate I! which is provided with a central opening I8 that registers with its respective port I3. These plates are rolled to provide a curvature which corresponds with that of the periphery of the steel shell or cylinder 50. These discs or plates I! are welded to the shell or cylinder i0. A pipe sleeve I9 isthen Welded to each plate l7, This pipe sleeve, of course, is internallyscrew-threaded at 20QA pipe plug 2!, see Figs. 1 andZ, is then threaded intofeach one of the pipe sleeves I 9 for closingthe several ports. The kiln is then ready to be returned to the productionline. e i

While in operation, the fire ring H will start forming and will continue to build up until loss of draft controllowers the efiiciency of the kiln to a point where removal of the ring becomes necessary. I l

A suitable number of carbon dioxide charged cartridges are employed for actually accomplishing the step of breaking up the slag formation into large chunks which can be discharged from the kiln while the latterisrotating. Onesuch cartridge22 is shown in Figs. 2 and 3. For a clear understanding of the'detail features of construction and mode of operation of this cartridge, reference may be made to the patent issued to Frank H, Armstrong on December 26, '1933, whichbears No. 1,941,196. Briefly described, the cartridge includes a main body which is of hollowconstruction and which has a discharge cap at one end that is provided with a plurality of radially directed ports. The other end of thishollow main body is closed by a charging cap through which the interior or chamber of the body is charged with liquid carbon dioxide at a pressure of approximately 1000 poundsper square inch. The discharge cap has heater unit is electrically ignited and burning of i the same effectsgasification of the liquid charge. When the'desired pressure is reached, thetime required being only a fraction of a second, the gasified carbon dioxide is released by rupturing of the aforesaid wall and the charge passes through the discharge cap and is deliveredradiallytherefrorn through the several ports. This highly compressed carbon dioxide gas is released at a pressure in the neighborhood of 15,000 pounds per square inch It enters the veins and crevices or. cracks of the material into which it is discharged. The expanding of this gas ex;- erts a slow; heaving fo rce against the material which e1fectively breaks upthe latter into large chunks; q,

Referring specifically to Fig,'3, the body of thistype of cartridge is designated by the reference character 23.. The charging cap is disclosed at 24 while the discharge cap, with its radial port, is designated by the reference character 25.

For the purpose of attaching one of these cartridges 22 to the kiln at a port 73, a suitable length of pipe 26 is provided. A sleeve 2'! is welded exteriorly of the pipe. This sleeve is externally screw-threaded at 28 so that it may be threaded into the sleeve l9 which is permanently attached to each port reinforcing plate ll. The outer end portion of this pipe section 25 is longitudinally slotted, as at 29, so that this end of the pipe can be contracted to firmly clamp the cartridge 22 within the bore of the pipe. Figs, 3 and 6 disclose the yoke type of clamping device 30 which is employed for contracting the slot ted end of the pipe so as to firmly anchor the cartridge Within the bore of the pipe.

A suitable handle 3! is permanently attached to the pipe section .26 to facilitate threading its sleeve or bushing 21 into the pipe sleeve I9. A detachable handle 32 is clamped on the cartridge 22 to facilitate insertion and withdrawal of the same with respect to the bore of the pipe section 26.

Assuming now that the fire ring if has arrived at a condition where it must be removed,

the plugs 2| are threaded out of three or four of the pipe couplings l9 located in two diametrically arranged lines of ports of the kiln. The use of three of these ports in each of the two lines frequently will be sufficient but all four ports of each line may be necessary under certain ring formation conditions. An ordinary jack hammer, using inch steel and a bit spread of about 2 inches, then is employed for providing a-pocket 33 in the fire ring H in alignment with each port which is opened up by the removal of its plug 2!. This pocket 33 should be formed deep enough to accommodate the discharge end of the cartridge 22 with the ports of the discharge cap 25 located from one to two inches inwardly of the inner face of the refractory lining l2.

The kiln, preferably, is positioned so that one line of opened ports will have their axes arranged at approximately a ninety degree angle with respect to the floor underlying the kiln. When in this position, the required three or four carbon dioxide cartridges are positioned in the ports and are fired one or more at a time. These three or four shots will cause a trench to be cut the full length of the fire ring. This trench is produced by the liberated carbon dioxide gas charges which, as a result of their heaving action, dislodge the slag ring in the form of large chunks. The trench thus formed extends the full depth of the ring; i e., the slag formation is entirely freed from the refractory lining l2 and leaves the inner surface of the latter exposed.

Aiter the formation of one such trench, the kiln is rotated a hundred and eighty degrees to position the second line of prepared ports in the position occupied by the first used ports. Three or four cartridge charges are then released on this side of the kiln and a second trench is formed by the displacement of the slag in the form of large chunks.

With these two trenches formed in the fire ring, rotation of the kiln will frequently allow each half of the slag formation remaining in position to break loose and drop free from the face of the kiln lining, however, it is on occasion necessary to assist the drop by one or more cartridges strategically positioned in the ports of the unused rows. As the kiln continues to revolve, these chunks of slag are fed or moved toward the discharge end of the kiln, As these chunks approach the discharge point of the kiln, some of the larger sized ones may be in danger of damaging the coal feed pipe. These large chunks, however, are near enough to the discharge end of the kiln to be easily broken up so that they will pass the coal pipe without danger of damaging the same,

It has been definitely established that an experienced crew of three or four men, having all of the equipment available and ready for use, can perform the operation of completely removing the fire ring in from one-half to three-quarters of an hour. After this extremely short shut down period, the kiln may be put back in operation with the fire ring completely removed therefrom.

Figs. 1 and 2 disclose the provision of four rows of ports through the kiln wall. Ordinarily, two diametrically arranged rows are all that need be provided. However, these two additional rows of ports can be employed to accomplish slight modifications of the previously described procedure. For example, a desired number of cartridges may be fired through each one of these four rows by starting with any one row and proceeding circumferentially of the kiln cylinder in either direction. By thus utilizing the succeeding rows, the slag formation can be broken loose in four sections instead of the two previously described half sections. This procedure may be preferred if it is found that the half sections are reluctant to break loose and drop after cutting two diametrically arranged trenches.

It is to be understood that I do not desire to be limited to the exact order of steps as they have been disclosed, for variations and modifications of the same, which fall within the scope of the accompanying claims, are contemplated. It further is to be understood that the particular type of apparatus herein shown and described is to be taken only as a preferred example of the invention, and that various changes in the shape, size, and arrangement of parts may be resorted to without departing from' the spirit of the invention or the scope of the subjoined claims.

Having thus described the invention, I claim:

1. A method of removing fire rings from rotary kilns, comprising suddenly releasing a preconditioned charge of highly compressed carbondioxide gas simultaneously in a plurality of radial directions into each one of a series of relatively shallow, longitudinally and circumferentially spaced pockets formed in the periphery of the ring formation to cause the expansion of the gas to separate the ring from the kiln lining and break up the same into large chunks, and rotating the kiln to move the chunks to and spill the same from the discharge end of the kiln.

2. A method of removing fire rings from rotary kilns, comprising suddenly releasing a preconditioned charge of highly compressed carbondioxide gas through each one of a longitudinally aligned series of spaced openings formed in the wall of a kiln and into the region of the periphery of the ring formation to cause the expansion of the gas to separate from and break up 2,301,855 into large "chunks a; sufiicient amount of the formation to produce a trench extending throughout the length and depth of the ring, repeating the aforesaid trench forming operation at a location spaced.circumferentially of the ring, rotating the kiln to cause the portions of the ring lying between said trenches to. pull loose from the kiln lining and break up into large chunks as a result of falling, and continuing rotating the kiln until the said chunks have been moved to and spilled from end of the kiln.

3. A method of removing fire rings from rotary kilns, comprising releasing a number of charges of highly compressed gas through a longitudinally aligned series of spaced openings formed in the fall of the kiln and into a corresponding number of shallow pockets formed in the .periphery of the ring formation to cause the expansion of the gas to dislodge and break up into large;

chunks a suificient amount of the formation to produce a trench extending throughout the length and depth of the ring, repeating the aforesaid trench forming operation at a location spaced. circumferentially of the ring, rotating the kiln to causethe portions of the ring lying between the trenches to pull loose from the kiln lining and be broken up into large chunks as a result of falling, and continuing the rotation of the kiln until the said chunks have been moved to and spilled from the discharge end of the kiln.

4. A method of removing fire ringsfrorn rtary kilns, comprising cutting a number of relatively spaced pockets in the periphery of the ring formation, successively releasing into each one of said pockets a charge of highly compressed gas to cause expansion. of the gas to separate 'the ring from the kiln lining and break upthe same into large chunks, and rotating the kiln to move the chunks to and spill the same from the discharge end thereof.

5. A method of removing fire rings from rotary kilns, comprising cutting two circumferentially spaced, longitudinally arranged rows of shallow pockets in the periphery of the ring formation, successively releasing into the pockets of first one row and then the other a charge of highly compressed gas to cause expansion of i the gas to separate the ring from the kiln lining rotary kiln formed of a shell provided with a h refractory lining and having an opening extending through said shell and lining where the fire ring of the kiln forms, of a container confining a charge of liquid carbon dioxide which is to be gasified for producing a charge of highly com-. pressed gas, said container having discharge openings at one end through which the gas charge is released, and means for attaching said container to the kiln shell With the discharge end of the container extending into the opening formed in the shell and lining so that the expanding force of the charge of gas, when released, may be applied to the peripheral portion of the fire ring to break the latter loose from the kiln lining.

'7. Fire ring removing apparatus of the type described, comprising the combination with a rotary kiln formed of a shell provided with a refractory lining and having an opening extending through said shell and lining where the fire ring the discharge ofthe kiln forms, of a container confining a i charge of liquid carbon dioxide which is to be gasified for producing a charge of highly compressed gas, said containerhaving discharge, openings at one end through which the gas is released, and means for attaching the container to the kiln shell with the discharge end of the container extending into the opening formed in the shell and lining so that the expanding force of the charge of gas, whe n released, may be applied-to the peripheral portion of the fire ring to break the latter loose from the kiln lining, said container attaching means comprising .a sleeve permanently attached to the shell in alignment with its opening, and securing means detachably connected to the container and the sleeve for holding the container in place during the release of the charge. i

8- Fire ring removing apparatus of the type described, comprising the combination with a rotary kiln formed of a'shellprovided with a' refractory lining and having an opening ,extendmg through said shell and lining where the fire ring of the kiln forms, of a container confining a charge of highly compressed gas, said container having discharge openingsat one end through which the gas charge is released, andmeans for attaching the container to the kiln shell with the discharge end. of the container extending into the opening formed in the; shell and lining so that the expanding force of the charge of gas, when released, may be applied to the peripheral portion of the fire ring to break the latter loose from the kiln lining, said container attaching means comprising a sleeve permanently attached to the shell in alignment with said opening, a second sleeve detachably connected to thefirst sleeve, and means for detachably connectingthe container to the second sleeve for holding the container charge.

9. liire ring removing apparatus of the type described, comprising the combination with a rotary kiln formed of a shell provided with a refractory lining and having an opening extending through said shell and lining where the fire ring of the kiln forms, of a container confining a charge of highly compressed gas, said container having discharge openings at one end through which the gas charge is released, and means for attaching said container to the kiln shell with the discharge end of the container extending into.

the opening formed in the shell and lining so that the expanding force of the charge of gas, when released, may be applied to the peripheral portion of the fire ring to break the latter loose from the kiln lining, said container attaching means comprising a sleeve permanently attached to the shell in alignment with said opening, a second sleeve detachably connected to the first sleeve, a, tubular mounting member permanently fastened to the second sleeve and having. the container positioned in its bore, and means for detachably securing the container in the mount: ing means.

10. Fire ring removing apparatus of the type described, comprising the combination with a rotary kiln formed of a shell provided with a refractory lining and having an opening extending through said shell and lining where the fire ring of the kiln forms, of a container confining a charge of highly compressed gas, said container having discharge openings at one end through which the gas charge is released, and means for attaching the container to the kiln shell with in place during the release of the,

the discharge end of the container extending into the opening formed in the shell and lining so that the expanding force of the charge of gas, when released, may be applied to the peripheral portion of the fire ring to break the latter loose from the kiln lining, said container attaching means comprising a sleeve permanently attached to the shell in alignment with said opening, a second sleeve threadedly connected to the first sleeve, a tubular mounting member permanently fastened to the second sleeve and having the container positioned in its bore, handle means attached to the mounting member to facilitate connecting the two sleeves, and means including a clamp for detachably securing the container in the mounting member.

11. Fire ring removing apparatus of the type described, comprising the combination with a rotary kiln formed of a shell provided with a refractory lining and having an opening extending through said shell and lining Where the fire ring of the kiln forms, of a container confining a charge of highly compressed gas, said container having discharge openings at one end through Which the gas charge is released, and means for attaching said container to the kiln shell with the discharge end of the container extending into the opening formed in the shell and lining so that the expanding force of the charge of gas, when released, may be applied to the peripheral portion of the fire ring to break the latter loose from the kiln lining, said container attaching means comprising a sleeve permanently attached to the shell in alignment with said opening, a tubular mounting member for the container, means for detachably connecting the container to the mounting member, and means for detachably connecting the mounting member to the sleeve.

12. Fire ring removing apparatus of the type described, comprising the combination with a rotary kiln formed of a shell provided with a refractory lining and having an opening extending through said shell and lining Where the fire ring of the kiln forms, of a cartridge confining a charge of highly compressed gas, said cartridge having a discharge opening at one end through Which the gas charge is released, a mounting member, means for attaching the mounting member to the cartridge at the proper location relative' to the length of the cartridge so that When the cartridge is attached to the kiln shell the discharge end of the cartridge will be positioned to apply the released gas charge to the peripheral portion of the fire ring to break the latter loose from the kiln lining, and means for detachably securing the said mounting member to the kiln shell to properly position the cartridge.

WALTER R. CLIFFE.

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