US1544504A - Rotary kiln - Google Patents

Description

June so, 1925. 1,544,504

I C. J. TOMLINSON ROTARY KILN .2 Sheets-Sheet 1 Filed Oct. 3 1925 IN VE N TOR Gunman JZbMLzmoN A TTORNE YS June 30, 1925.

c. J. TOMLINSON ROTARY KILN Filed Oct. 30, 1925 2 Sheets-Sheet 2 Tiai.

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IN VEN TOR A TTORNE YS Cumoz cffomzzvsozv' Patented June 30, 1925. p i g UNITED STATES PATENT OFFICE.

' CLIFFORD J. TOMLINSOiN', OF WEST ALLIS, WISCONSIN.

, ROTARY KILN.

Application filed October 30, 1923. Serial No. 671,774

To all whom it may concern: In burning cement, raw material is in- Be it known that I, Cmrronn J. ToMLIN- troduced into the kiln in powdered form soN, a citizen of the United States, and a and flows through the kiln much in the resident of West Allis, in the county of manner of a liquid, traveling faster than Milwaukee and State of Wisconsin, havev granular material would travel; in other invented a new and improved Rotary Kiln, words, the raw material tends somewhat to of which the following is a full, clear, and run down the trough formed by the inclinacxact description. tion of the cylindrical shell rather than This invention relates to improvements strictlyto follow the helical path theoreti- 1 in rotary kilns, particularly to a rotary kiln cally determined by the rotation and incli- 55 for burning lime of that general type in nationof the shell. In the burning zone which the kiln is located at an inclined of'the kiln where the matter has attained a position, and consists of a long cylinder granular form, the forward movement of mounted to rotate. With this type of kiln the material is greatly reduced and it is 15 the raw material is fed to the upper end customary to limit the rate of rotation of of the kiln and travels by gravity as the the kiln because of the tendency of the kiln rotates to the discharge end, being raw material to travel faster than it should. meanwhile subjected to the action of a treat-. Yet another object of this invention, ing flame injected at the lower discharge therefore, is to provide a kiln which will 20 end of the kiln. A large proportion of the retard the movement of the powdered ceheat absorbed by the raw material in its ment andincrease the time of treatment of passage through the kiln is obtained by its the same, at the same time allowing an contact with the heated kiln lining passincrease in the rate of rotation of the kiln. ing under the raw material as the kiln ro- This increase in the rate of rotation will 25 tates. help to clear the burning zone of the kiln An object of this invention is to provide of its load of clinker, which as heretofore a kiln provided with a novel form of linmentioned, greatly reduced the space for ing so constructed, particularly in regard flame in the burning zone, and consequently, to what may be termed special projections the capacity of the kiln. At the same time shaped and arranged to constitute combing the increased rate of rotation will resultin means relative to the material, that a maxian increase of heat transference by means mum heating surface is presented to the of the' contact of the raw material and raw material passing therethrough, and a the kiln lining. lining which will serve to stir the raw ma As the term lining has been herein- 35 terial, without great mechanical impetus to above employed, such term has been used the comparatively slow gravity travel of in the sense ofincluding, as well, the prothe material axially of the kiln and 'withjections characteristic of the comb essenout a bodily lifting of the material to such tially provided by the present invention,

a height above the bottom of the kiln as but from now on, and particularly in the toresult in noticeable up-liftings and downclaims annexed, the term lining will be droppings of masses of the material, that used as meaning the usual fire-brick or other is to say, a lining which will truly comb suitable refractory lining as constituting a through all or most of each of the masses separate element from the element constiof material in the paths of said projections, tuted bythe arrangement of inwardly prebring all the material into contact with the means. lining. and ivi'th'the heated projection-sur- This distinction must here be clearly faces thereof;particularly during pasage. made, because another important object of of the material from the upper to the lower the invention is the provision of such lining end of the kiln, I of a material havin a different heat-ab- 195 I have suggested that" the kiln was prisorptive character t an the material of marily intended for burning lime, but it is which the combing projections are made, to he understood that amjither important obthat is to say, a material which is rather joct of the invention-- i-to provide a kiln of resistant than otherwise to the-ready absorppeculiar advantage in-;ceinent,burning. tion of heat and consequently to the ready and thus, more intimately than heretofore, sented projections comprising the combing delivering of such heat by conduction or radiation to a'contiguous or adjacent substance. Preferably, such material is also a highly refractory one. Since, otherwise stated, the object of the invention here being considered is so to construct the combing projections that, on leaving behind the combed material, they will absorb the maximum amount of heat from the longitudinal flame at the upper central portion of the kiln, will lose as little of this heat by conduction as possible to the kiln lining before being again combed through the lowlying material, and will give up as much of this heat by conduction as possible to said material while again combing through the same, an im ortant object of the invention is to provi e such lining of a material substantially heat-absorptive and to provide such projections of a material considerably more heat-absorptive than the lining.

A further ob ect is. to provide a kiln lined and interiorly equipped in such a manner that not only a greater number of heated surfaces are presented to the material passing therethrough, but a greater-number or rather a greater total area of heating surfaces, to wit, heating surfaces of said combing projections, are subjected to the action of the flame without materially obstructing the How of heating gases through the kiln. To this end, each combing projectionis preferably elongate in -or substantially in the. direction of rotation of the kiln, and preferably includes a forwardcutting edge, this edge preferably sloped rearwardly from root to crest of the projection,-such sloping, I have discovered, acting also considerably to increase the efficiency of the projections as pure combing rather than li ing or combing and lifting instrumentalitiesrelative to the material being treated; and eachv projection, thus preferably or otherwise constructed, further includes at least one edge-following face of rather lar area arranged transverse or substantially transverse to the axis of rotation'of the kiln, so as to meet the flame substantially broadside on. Remembering again that the projections are essentially combing elements, such face, it will be seen, may be rather appropriately also designated as a plowing face, or a" face which swee s through the material without lifting tlie same to a sufficient height above the bottom of the kiln so as subsequently to drop any of the material or enough of the material what may be termed an air-path,

through as is characteristic of the lifter projections of the prior art, to result in any appreciable loss .of the stirred material following subjection of small portions or particles thereof to the blast of the flame. And thereby a very important object of the invention is attained, which is to obviate the really con messes siderable loss of material heretofore encountered in all kilns equipped with pro jections which raise portions of he material and drop thelatter transversato the line of travel of the flame. It will be apparent that in the case of my invention the fine powdered material being treated, will. pile up somewhat before and around the plow or comb, and then, as the plow forces its way through the mass," this pile will be constantly forming and running past the plow in intimatecontact with its hot lowing, flaring surfaces, andcontinue to do so until the plow passes up'out of the mass without lifting the same. Each projection of the prior art, being without these plowin surfaces, segregates the mass of material being treated in front of the lifting surface, which stays there until such material is lifted clear of the rest and moved across the path of the flame and a large part blown out of the kiln by the gases passing through the. same,

while the mass of material, in' the lower portion of the kiln that is not lifted, will be constantly cascaded from the sides or ends the same as that material which is lifted. is

cascaded from the top, so that the material cascaded from the sides or ends cannot come into intimate contact with the lifter, thereby completely failing to attain the object of the present invention.

With. these and other objects in view, the invention consists in certain novel features of construction, and combinations and arrangements of parts as will be morefully hlereinafter described and pointed out in the 0 arms.

This application isa continuation in art,

of application 16,1922.

In the accompanying drawings,

Serial No. 561,261, filed ay Figure 1 is a perspective view of akiln embodyin upper en pose the pro ections.

my invention, 7 of the kiln broken away to exwith parts of the kiln lining and a number of the igure 2 is a fragmentary interior plan view showing a portion ofthe lining. showing more clearly the arrangement of the projections as at present preferred; the ar-.

1 and 2 corresponding in rows of Figures direction.

Fi ure 3 is a perspective view of one of the lining bricks of, Figures 1 and 2, this brick including a combing projection as an integral portion thereof.

Figure 4 is a similar triew illustrating a slight modification of the form of brick shown in Figure 3, and with the brick wholly comprisin such projection.

Figures 5 to 12, th inclusive, show somewhat diagrammatically, the arrows here corresponding to those of Figures 1 and 2, various possible modifications of, fl1e cross-sec= tional and inclinational characteristics of combing projections which may be employed according to the invention.

Figure. 13 is a transverse section through the kiln, but showing merely one of the projections intersected by the plane of the section, and showing that projection combing {hrough the material in the bottom of the 1111.

Figure 14 is a fragmentary view, being substantially a section on the line 1414 of Figure 13, showing the action of each projection relative to the material combed, it being noted that the showing of the projection here corresponds to the's'howings of the projections of Figures 5 to 12.

Figure 15 is a view similar to Figure 13,

but showing graphically what occurs when other than a combing projection is employed.

Figure 16 is a view similar to Figure 14, but taken substantially-on the line 1616 of Figure 15.

Referring in detail to the drawings, and first to Figures 1, 2, 13 and 14, my improved kiln consists of an elongated cylindrical body portion 1 mounted to rotate in any approved manner upon a plurality of supports 2. This kilnis primarily intended for the burning or treating of lime which is introduced into the upper end of'the same and fed by gravity toward the lower end as the kiln rotates.

A treating flame is injected into the lower end of thekiln to treat the raw material as it passes'therethrough; the manner of treating the raw material, however, is conventional and I have-not shown any means for doing so.

The kiln is provided with a lining as hereinabove defined, or lining proper 3, and a plurality of inwardly directed combing projections 4. Such lining equipment may be formed of a plurality of inlaid bricks 3 integrally carrying projections 4, as shown in Fig. 3, in which case kiln lining and spacing bricks 5 are interposed between the bricks 3, as seen most clearly in Figure 2, or such lining proper may include projecthin-incorporating bricks 7 as shown in Figure 4 with which suitable lining bricks are interposed and interlocked,so that a staggered arrangement of the pro ections 4 is provided upon the inner surface of the cylinder 1. It will, of course, be understood that a strictly staggered. arrangement is not essential, as any arrangement which accomplishes the purpose, however irregular the spacing, falls within the present invention. But I prefer to employ a lining proper the elements of which are not integral with the combing pro ections, and hence I could, for example, well employ the arrangement described just above in connection with a projection-brick like that of Figure 4, since then the brick 7 or equivalent, or the portion thereof constituting the combing element projecting above the interior face of'the kiln lining, may be formed of a much greater heat-absorptive material, than the material of which the lining proper is formed, in order to attain the heat-conservation feature of the invention while retaining the material-combing feature thereof. The projections 4 ofFigures 1 to 4 are substantially rectangular in shape,'or,'to be more specific, ar in the form of frustrated quadrilateral pyramids. The inclined walls of these pyramids are located at angles to the direction of travel of the projection during rotation of the kiln. Each projection is'elongated in such direction, and includes a forwardly presented cutting edge 6 adapted to cut through the material in the cylinder without lifting the same, and the two adjacent faces of the projection have alternately a plowing action to turn over and mix up the raw material 8 engaged, as in Figures 13 and 14Qand a broadside-on travel through the flame zone above such material; all to the end that the projections 4 not only serve to thoroughly comb the raw material passing through the kiln, but also the flame and to the material, and all without lifting the material for subsequent release ,to drop through space back'to the-- bottom of the kiln.

Referring now to Figures 5 to 12, these views, as will be understood, of course ilustrate merely various of the'many possible designs for a projection 4 according to the invention; each of the projections shown having peculiar advantages of its own. As-

suming them all to be made of. the same material, some of them are obviously stronger than others, while some have greater combing efficiency. As will 'be observed,

the projections are not only shaped differently, as to the angles, areas and numbers of the follower surfaces in rear of their cutting edges 6, but in some only of said projections, said surfaces are arranged symmetrically relative to the lines of travel of the projections; in some only of' said projections, one of said surfaces is parallel to said line of travel, while in others, all said surfaces, in order to provide but a single plowing surface in rear of the cutting edge, are offset to one side of said line of travel. An example ofthe kind of projection last referred to-is shown inFigure 12, where there are provided two flaring surfaces 7 and 7", but of which the surface 7 is the only plowing surface. The particular kind of projection selected, as to the characteristics above discussed, will of course depend on whether or not the gravity feed of the material longitudinally of the kilnis to be p The fact that the comb elements illus trated in Figures 5 to 12 are all symmetrical about an axis that may or may not be parallel to the direction of motion (except in the case of Figure 8) is only an inadvertent coincidence, and it will be understood that combs of various other and various asym metrical shapes may also be employed within the invention. It will also be understood that the number of possible shapes of comb teeth is very great and it would be impossible to show them all.

In operation, the kiln may be heated before the material is introduced therein, so that by the time the raw material reaches the projections 4:, they will present heated surfaces to the material aiding greatly in thetreatment of the'same. The ordinary kiln will be lined with these projections through the upper two-thirds of its length, but, of course, the exact proportion of the lining which is formed with these projections is immaterial and may be infinitely varied in accordancewith the work to be treated and the conditions under which the kiln is used.

Further to explain the operation of the invention, it is emphasized that the heatconservation feature of the invention is ac complished by constructing and arranging the projections so that, on the one hand, they are combed through the material as above described, and on the other, between one such combing and another they are passed through the path of the hot gases and present preferably their broad faces to the flame, such faces being in rear of a distinct cutting edge at the head of each projection, such cutting edge being sloped rearwardly from root to crest of the projection as indicated at 6" in Figure 13. The projections are preferably of a substance with a high heat-absorbing and conducting capacity; while the fire-brick or other lining proper of the kiln must be, on the contrary, insulating toprevcnt heat being transferred to the outer metal parts of the kiln. The present invention, in providing combing projections, thus does not depend at all upon lifting and showering the material through the flame and solid gases, as heretofore proposed; indeed these lifters or conveyor projections of the prior art are in many cases specially arranged and designed so as not to interfere with the showering of the lifting material across the flame path. Such lifting and showering of the material cause great dnst losses, which must be overcome by costly and elaborate dust-collectors. Some of the propelling projections of the prior art, have the disadvantage of protecting the material from the very flame with which it is intended to calcine said material; and such projections have been specially designed so as to present broad surfaces to the material to lift and drop or move the material a considerable distance lengthwise of the kiln. In a word, all the previously proposed litter or propelling projections have knife or cutting edges only because they are broken spirals for moving the material lengthwise of the kiln, and none have cutting edges to avoid lifting or moving the material, that is, to insure combing the material. The action of a lift er or projection of the kind just referred to is, for the purpose of understanding the present invention more clearly, graphically illustrated in Figures 15 and 16; especially with the latter views compared with Fig ures 13 and 14-. The projection 7 of Figure 13, it will be seen, combs through the material 8 in the direction of the arrow shown, without appreciably lifting any of the material, while both flaring surfaces of the projection immediately in rear of the cutting edge 6", are always in all parts totally changing contact with the material being combed. On the other hand, the lifter projection L of Figures 15 and 16 not only showers the material as indicated in Figure l5 and until said projection reaches the top of the kiln, but while traveling through the material in the bottom of the kiln, establishes and carries ahead-ct it a compacted mass of the material, as indicated at M in Figure 16; this mass persisting as such during practically the whole passage of the comb through the material and therefore defeating a-heat interchange between the projection and the part of the material relative to which said projection and the mass M are moving. Finally, of course, the

elongation of the projection L is generally transverse to its direction of travel, if such projection has an elongated cross-section at all, and so the surfaces thereofmarked L in Figure 16 are not at all analogous to the surfaces provided by the rojection of the present invention in rear 0 the cutting edge of that rejection.

The undamental difference between the action of the comb of the present invention over the lifter or lifters of the prior art cannot be too much emphasized. The

plowing action characteristic of the present invention piles the material ahead of it naturally, and by so doing utilizes more of the lowing sur aces than would otherwise be t e case; whereas such litters will cascade the material from thetop and sides, tending to throw such a material away from the heated surface of the lifter, instead of is practically entirely overcome by face adjacent its cutting edge.

' tions being provided with a flaring p bringing such heated surfaces, as in the case of the present invention, into the most ideal contact with the .material for heat transfer. I l 1 The present invention has been found to be most valuable in regard to the manufacture of Portland cement; since the previous dust'loss, in kilns having projections as lllustrated in Figures 15 and 16, and amounting to as'much as 30% of the raw material,

employing combing projections according to the present invention. It 18 well known that the raw cement material must-be powdered to the fineness of flour before being fed to the kiln, in order to make the chemical reaction possible. But what has ust been said should not indicate that the present invention is not of equal value in the wet process of cement manufactureythe projections characteristic of the present 1nvention then being employed only of that part of the kiln where the wet material 7 would not stick to the proj'ections,=or where the material is dry enough so that it can be acted upon by the combs.

Numerous slight changes and alterationsv might be made in the general form and arrangement of the parts described without departing from the invention, and hence I do not wish to limit myself to the -prec1se details set forth but consider myself at liberty to make such changes and alterations as fairl fall within the spirit and scope of the'app nded claims. I

I claim:

cutting edge presented in the direction of rotation of the kiln, and each of'said projections being provided with a plowing sur- 2. In a rotary kiln, a refractory kilnilining of'inwardly presented projections, each of said projections including a plurality of heat absorbing faces, and each of said projections including a cutting edge presented in the direction of rotation of the kiln, and a flaring plowing surface adjacent the cutting edge, said pro'ections being capable of passing through t e matter being heated without propelling the same. 4

3. A rotary kiln of the class described including an arrangement of inwardly resented projections on its inner face, eac of said projections being provided with a cut ting edge presented in thedirection of rotation of the kiln, and each of said rojecowing surface adjacent its cuttinged e.

4'. A'rotary kiln of the class ascribed in cluding, an arrangement of inwardly pretions being sented projections on its inner'face, each of said projections being provided with a cutting edge presented in the direction of rotation of the kiln, and each of said projections being provided with flaring surfaces tation of the kiln, and each of said projec tions being provided with flaring surfaces adjacent its. cutting edge, said projections being of greater length than width in the direction of rotation of the kiln.

6. A rotary kiln of the class described including an arrangement of inwardly presented projections on its inner face, each of said projections being provided with a cutting edge presented in the direction of rotation of the kiln, and each of said projecprovided with a fiaring plowing surface adjacent its cutting edge, said projections being of substantially frustrated pyramidal shape.

7. A rotary kiln of the class described including an arrangement of inwardly presented projections on its inner face, each of said projections being provided'with a cutting edge presented in the direction of rotation of the kiln, and each of said projections being provided with flaring plowing surfaces adjacent its cutting jections being of substantially frustrated quadrilateral pyramidal shape. 1. A rotary kiln of the class described,

8. Ina rotary kiln, a kiln lining comprising a plurality of bricks, alternate bricks including inwardly presented projections, each of said projections including a plurality of heat absorbing faces, each of said projections includim a cutting edge presented in the direction from its base to its'inner flared edge.

9. In a rotary kiln,

end and incuding plowing surfaces ad acent its cutting a kiln lining comprising a plurality of bricks, alternate bricks in-- said projections being provided with a cut-v ting edge presented 1n the direction of rotation of t e-kiln and each of said projecedge, said pro-v of rotation of the kiln, and each of said projections ta ering.

tions being provided with diverging surfaces adjacent its cutting edge, and one of said surfaces having a greater angle of incidence with the radial axis of the kiln'than the other of said surfaces.

11. A rotary kiln of the class described, including an arrangen'ient oi inwardly presented projections on its inner face constituting combing means relative to the material being treated in the rotating kiln, each of said projections being provided with a cutting edge presented in the direction of rotation of the kiln and each of said projections being provided with diverging surfaces adjacent its cutting edge.

CLIFFORD J. TOMLINSONE

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