US2895725A - Rotary kiln construction - Google Patents

Description

July 2 1 1959 F. J. ANDERSON w2,895,725

ROTARY 'KILN oNsTRUcTIoN 2 Sheets-Sheet 1 Filed Deo. 26, 1956 frana/gy,

F. .1.A ANDERSON 2,895,725 ROTARY KILN CONSTRUCTION July 2l, 195,9

2 Sheets-Sheet 2 Filed DBC. 26, 1956 INVENTOR.

lfm/Quia Patented July 21, 1959 ROTARY KILN CONSTRUCTION Frank J. Anderson, Laramie, Wyo., assignor to Monolith Portland Midwest Company, Los Angeles, Calif., a corporation of Nevada Application December 26, 1956, Serial No. 630,618

16 Claims. (Cl. 263-33) This invention relates to new and improved rotary kiln construction. This application is a continuation-in-part of a co-pending application Serial No. 486,227 tiled February 4, 1955, now abandoned entitled, Kiln Construction.

Rotary kilns are conventionally utilized in a large number of industries for a variety of purposes. In certain industries such as, for example, the cement industry, such rotary kilns are constructed out of a cylindrical metal shell. Within such a shell there is normally located a brick lining serving to protect the shell proper from the action of heat generated in the kiln during various operations such as, for example, sintering cement. Kilns of this category are conventionally mounted so that the axis of the kiln shell is located at a slight angle to the horizontal. With this type of mounting material Will flow or travel through the kiln from the upper end of it to the lower end of it as the kiln shell is rotated.

Because it is extremely expensive to replace the brick lining in rotary kilns of the class indicated in the preceding paragraph, it is important that these linings be con- -structed in such a manner so as to last as long as possible during use. In order to provide brick linings which will not fail in a short period of time, a number of different types of kiln lining constructions have been suggested. One of the methods is to attach to the individual bricks forming a kiln lining various metal shims which extend along the sides of the brick so as to be either in contact with or in very close proximity to the metal shell in a rotary kiln. These shims are-not considered to be completely satisfactory in prolonging the life of a rotary kiln lining. They serve to conduct undue amount of heat from the interior of the kiln to the metal shell. This tends to result in a number of things. One of these is that heat is removed from Within a rotary kiln during the use of this kiln, and hence, the removed heat is not available to do work within the kiln. Another of these items is that heat conveyed to the rotary kiln shell tends to result in the shell becoming unduly hot. This, of course, is what a lining is installed in a rotary kiln to avoid.

Another suggested method for prolonging the effective life of a lining within a rotary kiln involves the use of layers of different types of brick. ln one example of this type of structure layers of acid and basic brick are placed in contact with one another within a rotary kiln shell. Laminated structures of this category have been proposed in which the layers of brick used are attached to one another so as to be capable of being handled as a single brick and in which metal shims are used in conjunction vvith such laminated brick structures. Constructions of this type are not considered to be acceptable for a number of reasons. Since two types of bricks are employed they are comparatively expensive. Further, different types of brick differ from one another in both chemical and physical properties. As a result the bond which may be created between ditferent types of brick after slight use.

It is an object of this invention to provide rotary kiln constructions which are not subject to the various disadvantages and limitations of the various prior art constructions broadly indicated in the preceding discussion, and which are not subject to the various disadvantages and limitations of other related constructions. Afurther object of this invention is to provide new and improved brick linings for rotary kilns which are capable of comparatively long use. A related object of the invention is to prolong the life of brick linings for rotary kilns by means of devices or members which are applied to and used in conjunction with brick so as to strengthen the same and so as to reduce the Wear on them. With the constructions of this invention specially shaped metal shims as will hereinafter be described are employed so as to hold the bricks in a rotary kiln in place. These metal shims serve a number of functions in preserving the rigidity and shape of a complete kiln structure, in prel venting and inhibiting cracks, and in preventing undue loss of heat to the exterior of a rotary kiln, and these shims may have the shape of either segments of a circle or ring of any desired length or of a complete circle. Other objects and advantages of the invention will be more fully apparent from the remainder of this description, including the appended claims and the' accompanying drawings in which:

Fig. 1 is a cross-sectional View of a rotary kiln constructed in accordance with this invention;

Fig. 2 is a partial cross-sectional view taken at line 2 2 of Fig. 1;

Fig. 3 is a perspective view of a metal shim employed in the kiln shown in Fig. 1;

Fig. 4 is a perspective view of a modified metal shim capable of being employed with the invention;

Fig. 5 is a perspective view of another modied metal shim capable of being employed with the invention;

Fig. 6 is a cross-sectional view similar to Fig. 1 of a further modied structure of this invention;

Fig. 7 is a cross-sectional view taken at line 7-7 of Fig. 6;

Fig. 8 is a cross-sectional view similar to Fig. 7 of still a further modified construction of this invention;

Fig. 9 is a perspective View of the modified metal shim of the invention;

Fig. l0 is a cross-sectional View similar to Fig. 2 of a modied structure utilizing the shims shown in Fig. 9; and

Fig. 11 is a partial cross-sectional view taken at line 11-11 of Fig. 10.

In all figures of the drawings like numerals are used to designate like parts whenever convenient for purposes of illustration and explanation. The accompanying drawings are not to be taken as limiting this invention in any respect. Thoseskilled in the art to which this invention pertains will realize that these drawings are primarily intended so as to clearly designate the preferred nature of this invention. Obviously the dimensions and/or relative sizes of the various parts in the constructions shown can be changed so as to adapt the invention for use in various sizes of rotary kilns and with various types and sizes of bricks.

In order to understand the invention it may be stated in essentially summary form that it involves rotary kilns which are formed so as to include: a cylindrical metal shell; and a lining located within the shell, this lining being composed of courses of brick between which there are positioned specially formed metal shims. The actual details of this invention are more fully and precisely set forth in what may be considered a summary form in the appended claims.

In Figs. 1 and 2 of the drawings there is shown a rotary .kiln 10 of known4 exterior construction which is formedso as to include a metal shell 12 serving to hold a brick lining 14 consisting of a plurality of rows or courses of brick 16 located in planes transverse or perpendicular to the axis of the shell 12. This lining 14 is composed of individual, conventional bricks 18, each of which is formed in a conventional manner out of a single composition so as to have a uniform physical and chemical composition throughout. These bricks may be of any known common variety. Thus, they may be either acid or basic in category. It is, of course, preferred that the brick 16 be refractory in character for use in a rotary kiln.

Between the courses of brick 16 there are located metal shims 20 each of which is formed as indicated in Fig. 3 of the drawings. Each of the metal shims 20 is manufactured so as to include inner and outer edges 22 and 24 which are preferably shaped as arcs of different circles having a common center located at the center of the kiln 10. These shims 20 also have side edges 26. Along the interior edges 22 of the shims 20 there are located adjacent to the ends of the shim 20 small flanges 28 which serve during the placement of the brick lining 14 to hold the shims 20 so that the outer edges 24 are spaced from the metal shell 12 by engaging the bricks 18.

The distance from the outer edges 24 of the shims 20 to the metal shell 12 may be varied to a considerable extent. These outer edges 24 are located far enough in the shell 12 so that no heat is directly conducted from the shims 20 to the shell 12 during the operation and use of the kiln 20. Effective results have been achieved with this distance being about one inch. The shims 20 should be spaced far enough from the shell 12 so that the conductivity of heat to the shell through the area occupied by the shims 20 is not appreciably different from the conductivity of heat through an equivalent area of bricks 18 to the shell 12. It is presently preferred that the heat conducted through the area occupied by the shims 20 to the shell 12 be not greater than the heat conducted through an equivalent area of the bricks' 18 to this shell. The shims 20 are preferably of such a length as to extend along a number of individual bricks 18 within the courses 16. In the embodiment of the invention illustrated in Fig. 1 these shims 20 extend around the center of the shell 12 along an arc for approximately 30 of a circle. The length of these shims may, however, be changed as desired, depending upon various Vconditions such as the length yof metal strips available from which to cut the actual shims 20. With the preferred construction of the invention the shims extend along a course of brick the length of at least two bricks. The shims 20 may be formed so as to have any desired length. Thus, they can even be formed so as to have the shape of a ring extending completely around the interior of a kiln. When so formed they may be held in place by any of the means indicated in this specification.

The shims 20 are preferably located within the shell 12 in such a manner that the adjacent side edges 26 are positioned or staggered in an irregular manner throughout the length of the metal shell 12, as illustrated in Figs. 1 and 2 of the drawings. It is also preferred that these adjacent edges 26 be located not at the junction between two bricks in order to achieve maximum reinforcement. This staggered placement of the shims 26 serves to tend to prevent cracks from developing within the brick lining 14 and serves to prevent such cracks travelling from one of the courses of brick 16 to another of the courses of brick. Similar results can be noted without this staggered placement, but'these results are not considered to be a's pronounced as with the staggered placement described.

It will be realized in the aforegoing that the spacing of the outer edges 24 from the metal shell 12 results in a structure in which the shims 20 do not convey orconduct heat directly to this metal shell. This is advantageous inasmuch as it is normally desired when operating a' rotary kiln to maintain nearly as much heat as possible within the kiln so that such heat may be effective in promoting desired effects within the material being treated in a. kiln.

However, some loss of heat from within the interior of a rotary kiln is necessary in order that the interior portion of a kiln lining does not burn up. The structure shown and described here permits a restricted loss of heat to a kiln shell through the bricks employed so that the exposed surface of this lining is not damaged by overheating. With this structure the brick within a kiln is capable of absorbing and holding, and transferring to a load within a kiln suicient heat so as to operate as an effective heat exchange media as a kiln rotates. It will be realized that for heat control alone the length of the shims 20 is unimportant; the spacing of the shims from the kiln is responsible for these shims not conveying heat to the kiln shell. With the construction shown the shims 20, and the other shims hereinafter described are all regularly and uniformly spaced from the kiln shell.

The shims 20 also serve a number of other functions. As the kiln 10 is operated in a conventional manner the individual courses of brick tend to move or creep slightly toward the lower end of the kiln so that all of the bricks 18 are wedged in place. Such bricks are, of course, tightly wedged in place during installation. With the structures of the invention the metal shims 20 are edged between the individual courses 16. These shims bear against the individual bricks 18 in such a manner that a high frictional force is developed which [tends to prevent movement of the individual bricks 13 since these individual bricks are interconnected by the shims 20.

It will be realized from this that the shims 20 aid in maintaining a rigid lining structure which is relatively immune to cracking. It will be further realized that the factor termed kiln circularity is thus improved by the shims 20. Because of the rigid structure developed the tendency of the lining 14 to distort from other than a circular shape during the operation of the kiln 10 is effectively combatted with the shims 2t). Since movement of the bricks 18 caused by such distoltion of a rotary kiln in use has the effect of shortening the life of a brick lining the shims 20 aid in the maintenance of a rigid structure and in prolonging the life of a kiln lining.

The reinforcement of the kiln lining 14 by the shims 20 is considered to be primarily the result of the principal portions of these shims extending across the joints between individual bricks 18. In use the principal portions of the shims 20 serve to hold the lining 14 against movement because of the strength in these members. This strength is considered to be independent of the spacing of the principal portions of the shims 2t) away from the kiln shell 12, although such spacing is employed so as to obtain the complete advantages of the invention.

Since the strength of the shims 29 is important, it is preferred to form these shims out of sheet steel or iron because such material can withstand the conditions normally encountered when located as shown. Various equivalent metals or alloys can, of course, be employed. During the use of a kiln such as the kiln 1) reactions normally take place between the shims employed and the adjacent brick; also reactions between these members and the material treated within this kiln are normally apparent. Such reactions are commonly stated to lead to the formation of what may be termed eutectic mixtures and to the formation of certain specific composites. It has been found in practice that the principal portion of shims such as the shims 20 are not so reacted under the normal operating conditions in the cement industry; and, hence, remain in their initial form between the courses of brick so as `to reinforce the lining within a rotary kiln. Some reinforcement is obtained when the shims employed are relatively short; however, greater reinforcement occurs when shims of a comparatively long length as indicated in the preceding are employed, since large shims serve to distribute various stresses and strains encountered over a comparatively large area so that comparatively minor stresses and strains which would lead to cracking of the lining within a conventional kiln will in effect be absorbed so as not to lead to cracking.

Itis possible to modify the shim construction illustrated in Figs. l and 2 of the drawings in a number of ways. Obviously the anges 28 may be replaced by a number of different equivalent structures. What are in effect flanges have been created from shims formed out of at sheet iron by the simple expedient of welding small washers or rods to the interior edges 22 of such shims. It is not necessary that the shims 20 be manufactured so that the inner and outer edges 22 and `24 have different radii, although this is preferred since theoretically best heat control can be obtained with a symmetrical structure. For commercial reasons it is frequently desired to cut the shims 20 out of a single at sheet of steel. When this is done, it is possible to form both the inner and outer edges 22 and 24 so that bothof these edges have the same radii. This does not prove disadvantageous so long as the outer edge 24 of a shim 20 is manufactured of such a dimension as to be spaced from the metal shell 12 of a rotary kiln within which it is to be installed.

It is also possible to modify the shim 20 in a wide variety of other ways. In Fig. 4 of the drawings there is shown a metal shim 30 which has inner and outer edges 32 and 34 corresponding to the edges 22 and 24. With this construction the outer edge 34 is designed to bear directly against the metal shell of a rotary kiln. In order to provide the effective heat control which is necessary with this invention the section of the shim 30 adjacent to the outer edge 24 is provided with a series of perforations 36. Thus, the shim 30 is formed so that its outer portion is essentially of a Swiss-cheese like structure. Obviously such holes as the perforations 36 act to provide an insulating effect so that the principal portion of the shim 30 is spaced on the interior of a rotary kiln. The shim 30 cannot, because of the small cross sectional area of metal available for conducting heat to the outer edge 34, serve to conduct any great material amount of heat to the metal shell of a rotary kiln. The principal portion of this shim 36 is designed so as to be spaced from the shell of a rotary kiln so as to provide effective reinforcement as previously indicated. It should be specically noted that the perforated structure of the shims 30 is advantageous in developing a high degree of frictional force between the adjacent rows or courses of brick in a rotary kiln because of the irregularity of the shape of this shim 30.

The advantages of the invention can also be obtained utilizing a metal shim 40 substantially as shown in Fig. 5. This metal shim has interior and outer edges 42 and 44 which also correspond in shape to the edges 22 and 24.

From the outer edges 44 there project small extensions 46 which normally rest against the outer metal shell of a rotary kiln in order to space or position the principal portion of the shim 48 within the interior of the kiln. Here again, as with the shim 38, only a very small amount of metal is available to conduct heat directly to the shell of the rotary kiln. This amount of metal is so small as to not affect the operation of the rotary kiln V and is so small as to not result in any material amount of heat being transferred to the kiln shell. The principal por tion of this shim 4t) is available so as to reinforce a kiln lining.

Obviously a number of other expedients besides those specifically shown in Figs. 4 and 5 of the drawing can be utilized so as to space a metal shim formed in accordance with this invention from the metal shell of a rotary kiln; amongst these expedients is the use of a cardboard or other similar combustible material. In assembling a rotary kiln where none of the various spacing means illustrated in Figs. 3, 4 and 5 of the drawing are utilized, it is possible to position such a combustible material between the metal shim employed and a metal shell of a rotary kiln as the individual courses of brick are being installed. During use of a kiln constructed in this manner, the combustible material will burn out after the individual shims are rmly held in place. Equivalent non-combusd tible spacers can, of course, be employed.

In Fig. 6 of the drawing there is shown a modied rotary kiln structure `60 of the invention which includes a metal shell 62 within which there is positioned a lining composed of individual bricks 64 similar to the bricks 18 laid up in courses 766 extending in planes parallel to the axis of the shell 62. Between these courses 66 there are located metal shims `68, each of which includes outer and inner edges 7) and 72. To the inner edges 72 there are attached small anges 74 serving to hold these shims 68 so that the outer edges 70 are spaced from the shell 62. With this construction the adjacent edges 76 of the shims 68 are positioned against one another, and are staggered as shown in Fig. 7 so as to provide as much reinforcement for the lining of the structure 60 as possible.

If desired effective results can be created by providing a rotary kiln structure 80 as indicated in Fig. 8 of the drawing. Since this structure is substantially identical With the structure 6) the individual parts of it are designated by the primes of the same numerals previously employed. In the stnucture 80 the shims 68 are formed so that each of these shims 68 is of approximately the same length `as one of the bricks 64 and so that the edges 76 are not staggered as in Fig. 7.

In Fig. 9 of the drawing there is shown another modified shim 80 of the invention having the form of a complete ring formed out of sheet iron or the like so as to have an outer edge 82 and the inner edge 84. Small metal flanges 86 are attached to this inner edge 84 so as to engage the exposed surface of a brick lining 88 in a metal kiln shell 90 as indicated in Figs. l0 and 11. Thus, the anges 86 serve to position the outer edge 82 of the shim 80 away from the kiln shell 90 in order to accomplish the results previously indicated. Various other means such as are indicated in the preceding to be the equivalent of flanges, such as the flanges 86, can be substituted for these flanges. As will be .apparent in Figs. 10 and l1 the brick lining S8 is composed of rows or courses of brick 92 located in planes transverse to the axis of the kiln shell 90.

Those skilled in the art to which this invention pertains will realize that the shims 68 and 68 can be modified in the ways indicated in discussing the shims 20, 30, and 40 and that these latter shims serve substantially the same function as the former in a similar manner to the former. The shims 68 and 68 may also be constructed so as to be held in place by any of the means previously indicated. Thus, the flanges 74 and 74 may be omitted and extensions, a perforated structure, or

combustible spacers as indicated may be employed with these shims 68 and 68.

I claim:

1. A rotary kiln of the class described which includes: a cylindrical metal shell located with its axis at an angle to the horizontal; a lining composed of a single layer of brick, each of said brick being of a substantially uniform composition throughout, said brick being located in courses within said shell, said courses being located so as to extend in planes perpendicular to the axis of said shell; and metal shims having arcuate inner and outer ends positioned between said courses of brick so as to space said courses from one another, each of said metal shims extending transversely of the axis of the kiln across a plurality of the joints between successive individual bricks in said courses and being positioned Within said kiln so that the side edges of said shims are located next to one another and so that the side edges of said shims between adjacent courses of said brick are staggered with respect to one another, the principal portions 'of said shims being spacedfrom said shell so as to restrict the transfer of heat to said shell through said shims, and said shims being unattached with respect to said shell and free to move relative to said shell.

2. A rotary kiln as detined in claim 1 wherein said metal shims are spaced from said shell and wherein said metal shims are held with respect to said lining of brick by flange means formed on said shims, said flange means engaging the interior of said lining of brick.

3. A rotary kiln comprising: a cylindrical metal shell and a lining within said shell, at -least a portion of said lining including basic bricks each of which is of substantially uniform physical and chemical composition throughout and each of which has a complete face in full contact with said metal shell, and a metal shim positioned between at least one surface of each of said bricks and a surface of another of said bricks with each of said shims being spaced away from said shell so as to restrict the transfer of heat to said shell through said shims.

4. A rotary kiln as deiined in claim 3 including llange means formed on each of said metal shims and engaging the interior surface of said lining of bricks.

5. A rotary kiln as defined in claim 3 wherein said metal shims are formed of metal plates, each of said metal plates including extensions formed thereon engaging said shell so as to hold said metal plates out of contact with said shell.

6. A rotary kiln as deiined in claim 3 wherein said metal shims are formed in the shape of metal plates, each of said metal plates including a perforate outer portion, said perforate outer portions engaging said metal shell so as to space the principal portions of said plates from said metal shell.

7. A rotary kiln which includes: a cylindrical metal shell; a lining of basic bricks covering at least a portion of said shell, each of said bricks being of substantially uniform physical and chemical composition and having a complete face in full contact with said shell, said bricks being positioned in courses within said shell; metal shims positioned between said bricks in each of said courses, said shims serving to space said brick within each course from one another, and said shims being unattached with respect to said shell and regularly spaced away from said shell so as to restrict the transfer of heat from the interior of said kiln to said shell through said shims.

8. A rotary kiln which includes: a .cylindrical metal shell; a lining of basic bricks covering at least a portion of said shell, each of said bricks being of substantially `uniform physical and chemical composition and having a complete face in full contact with said shell, said bricks being positioned in courses within said shell; metal shims positioned between the bricks of adjacent courses, said shims serving to space said courses of brick from one another, and said shims being unattached with respect to said shell and regularly spaced away from said shell so as to restrict the transfer of heat from the interior of said kiln to said shell through said shims.

9. A rotary kiln which includes: a cylindrical metal shell located with its axis at an angle to the horizontal; a lining of bricks positioned in courses within at least a portion of said shell; and metal shims positioned between said courses of bricks, each of said shims extending transversely of the axis of the kiln across a. plurality of the joints between successive individual bricks in said courses, said metal shims being unattached With respect to said shell and being free to move with respect to said shell.

l0. A rotary kiln as dened in claim 9, wherein said courses extend circumferentially of said kiln and wherein said shims are continuous metal rings each extending completely around the interior of said shell.

ll. A rotary kiln which includes: a cylindrical metal shell located with its axis at an angle to the horizontal;

a lining of bricks positioned in courses within at least a portion of said shell; and metal shims positioned between said courses of bricks, each of said shims extending transversely of the axis of the kiln across a plurality of the joints between successive individual bricks in said courses, said metal shims being unattached with respect to said shell and being free to move with respect to said shell, and said shims being staggered with respect to each other.

12. A rotary kiln which includes: a cylindrical metal shell located with its axis at an angle to the horizontal; a lining of bricks positioned in courses within at least ,a portion of said shell; and metal shims positioned between said courses of bricks, each of said shims extending transversely of the axis of the kiln across a plurality of the joints between successive individual bricks in said courses, said metal shims being spaced away from and unattached with respect to said metal shell and being free to move relative to said shell.

13. A rotary kiln which includes: a cylindrical metal shell located with its axis at an angle to the horizontal; a lining of bricks covering at least a portion of said shell, each of said bricks being of substantially uniform composition and having a complete face in full contact with said shell, said bricks being positioned in courses within said shell; and metal shims positioned between the bricks of adjacent courses, each of said shims extending transversely of the axis of the kiln across a plurality of the joints between successive individual bricks in said courses, said metal shims being unattached with respect to said shell and being free to move with respect to said shell, said shims being staggered with respect to each other, and said shims being spaced away from said shell so as to restrict the transfer of heat from the interior of said kiln to said shell through said shims.

14. A rotary kiln which includes a cylindrical metal shell located with its axis at an angle to the horizontal; a lining of bricks positioned in courses within at least a portion of said shell; and continuous metal rings positioned between said courses of bricks, each of said rings extending transversely of the axis of the kiln completely around the interior of said kiln and across the joints between successive individual bricks in said courses, said rings being spaced away from and unattached with respect to said shell and being free to move with respect to said shell.

15. A rotary kiln as delined in claim 1 wherein said metal shims are held with respect to said lining of brick by extensions formed on said shims, said extensions engaging the interior of said shell.

16. A rotary kiln as defined in claim 1 wherein said metal shims each includes a perforate outer portion engaging said shell, said perforate outer portions serving to hold said shims with respect to said lining of brick.

References Cited in the le of this patent UNITED STATES PATENTS 802,631 Edison Oct. 24, 1905 2,148,054 Berlek Feb. 2l, 1939 2,154,813 Heuer Apr. 18,l 1939 2,192,642 Griith Mar. 5, 1940 2,230,141 Heuer Ian. 28, 1941 2,230,142 Longacre Jan. 28, 1941 2,462,289 Rochow Feb. 22, 1949 2,577,428 Mohr Dec. 4, 1951 2,829,877 Davis Apr. 8, 1958 FOREIGN PATENTS 8,919 Great Britain 1890 8,978 Great Britain 1904

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