Патент USA US2410236код для вставки
oa. 29,1946. ~2,410,236 w. A. REANEY METHOD ANDv APPARATUS FOR HEAT TREATING LOOSE BULK 4MATERIALS Filed June 27, 1945 @.Swim l„à Qkouìs@ W IlI .k$3o5i0 w.ueSiÉl 2E.N2.* l \\\\\\\\\\\\\\\\\\\\ ` \ \ \ \ ~ M 2,410,236 Patented Oct. 29, -_1946 UNITED STATES PATENT OFFICE 2,410,236 METHOD AND'APPARATUS FOR HEAT TREATING LOOSE BULK MATERIALS Watford A. Reaney, Delaware, Ohio --Applìcation June 27, 1945, Serial No. 601,763 vs' cnims. (ci. 263-22) heating ,air employed in 2 sustaining fuel com This invention relates to an improved process and apparatus adapted particularly for effecting bustion within the kilns. the calcination of calcareous materials, such as The present invention constitutes a continua tion-in-part of the disclosures set forth in my limestone, marl or the like, a general object of , ' _ , priorapplication, Serial No. 491,962, ñled June the invention being to-provide a new and im proved process and apparatus by which such calcination may be carried out with greater thermal efüciency .than heretofore has been ob tainable. . 23,1943. A further understanding of the invention will be obtained by reference to the following descrip tion and the accompanying drawing. ' . In the production of lime from limestone. it 10 In said drawing: » is'the ordinary practice to pass limestone through arotary kiln. While inthe kiln, the'limestone is iired to temperatures in the order of 1400. to ' Fig. l illustrates in schematic form a typica system for carrying out the invention; f 2000 degrees F. fied form of heat-exchanging pit. Fig. 2 is a detail view showing a slightly modi Such burning of the limestone liberates its-carbon dioxide content, leaving cal 15 ' Y gThe apparatus disclosed in the accompanying drawing comprises ‘a pair of kilns, indicated at I and 2, said kilns bein-g preferably of the rotary drum type. The drum of leach kiln is mounted as usual, with its longitudinal axis slightly an gree _of iineness suitable for various uses. In this customary operation, the heat contained in 20 gular to the horizontal, each drum being sup ported and rotated by conventional means. The the calcinedv lime is lostvto the atmosphere and upper or material-receiving end of each of the is notV applied to any useful purpose. v kiln drums enters a vertical flue orwaste gas ¿_gAccordingly, it is another object of the> inven outlety stack, shown at 6, the lower portion of tion to utilize more efûciently the available> heat each stack being provided with a limestone re in hot calcined lime by bringing the latter, im ceiving chute 1. Partially crushed limestone, for mediately uponY its discharge, from a calcining example, of such particle size that it will pass kiln into direct and intimate contact with'an through a 21/2 inch to 11A; inch mesh screen, is unheated body of limestone being charged to a delivered to the chute ’I of the kiln Iv in a manner calcining operation so that the charging material willbe preheated by contact withthe hot lime A’ hereinafter dei-ined. while crushed limestone of finer particle sizesuch as that which would pass before being introduced into thecalcining kiln. through ascreen of 1 inch to 1/'2 inch mesh is y It is still another object of the present in delivered to the inlet chute 'I of the kiln 2. The vention to provide a lime-calcining system in hot lime discharging end of each kiln is provided which two or more rotary kilns are arrangedmin with a `fuel burner 8 and the fan or blower 9 adjacent order with> the positions of their ma of each of these burners has its air inlet side terial-receiving and discharging ends y reversed connected with a duct system I6. A portion of with respect to each other, so that- the hot lime this system, forming a heat exchanger Illa, is discharged from one of said kilns may be con disposed in each of the stacks 6, so thatI the veniently brought into direct contact with cold limestone being fed as a charging* material to 40 air r'employed forv fuel combustion purposes in the kilns will be preheated by the waste gases the inlet end of the other Of, said kilns. n for more eilicient utilization in thekilns.r ¿i A further object is to provide a system of this cium oxide or lime as the calcined product. The heated lime upon its discharge from the kiln is cooled and thereafter crushed to a required de character in uwhich crushed limestone ofÍi-lne AThe outlet end of each kiln is formed With a lime-discharging chute II, the latter being ar mesh is employed as a charging material for one of the duplex kilns and a coarser >lime fed as the 45 ranged over a pair of mixing pits shown at I2 and I3 in order that the hot lime discharged charging material to the other kiln whereby, from said kilns may be directly received Within through a screening operation, »to provide for the saidpits. The hot lime of coarser particle -size separation of ñnished lime from the kiln-charging discharged from the kiln 2 is received in the pit limestone following heat-exchanging admixture I3, andis there brought into heat exchanging contact or relationship with crushed cold lime _' Still, a `further object of the invention is to stone of ñner particle size. By this operation, provide a >lime-calcining system in 'which' ad-y the temperature of the limestone is raised to pre ditional-heat economies are obtained by dispos heat the ñne limestone before it is introduced meiner-adjacent i0: the Combustioaeas. Outlet. iiiioiheiraletchgte orthgkiln I» ._ .. . of the kiln a heat exchanging meansgfor. p_re-` thereolî.;_> ~ v ' - 2,410,236 4 3 two kilns serves to preheat the fuel and intake After such heat exchange has taken place, the combustion air of each opposite kiln. coarse lime is separated -from the smaller sized particles of preheated limestone. Advantage ously, this may be accomplished by providing the I claim: 1. Process for heat-treating materials, which comprises advancing a stream of materials of relatively coarse particle size through a coniined pit I3 with a conveyor type elevator I4, the upper or discharge end I5 of this elevator being dis posed in registration with an inclined screen I6, heating zone, simultaneously therewith advanc ing a second stream of materials of relatively iiner particle size through a separate heating heated limestone will pass through the meshes 10 zone, bringing the heated materials discharged from each of said zones into direct heat-exchang of the screen for delivery to the inlet chute of so that as the mixture of coarse lime and ñne limestone passes over the screen, the íine pre The coarser lime gravitates to the ing and preheating relationship with previously lower end of the screen and from that point is conducted in any suitable mannerto aposition unheated materials of a particle size diiîering from that rof both said streams of materials the kiln I. of storage. A corresponding arrangement is provided for introducing the coarse limestone into the kiln 2. destined for delivery to each of the other zones, and separating the preheated materials from the finally heated materials prior to the introduction of the preheated materials into their respective Coarse limestone in an unheated state and at a heating zones. controlled rate of ilow is dropped into the pit I2 from a valved spout I1, where the coarse lime 20 stone comes into intimate heat exchanging rela tionship with the hot lime of iine particle size discharge‘d‘from the lime outlet II` of 'the kiln I. As this-mixture of lime and limestone cf 4dii? ferent particle size gravitates to the bottom of the pit I2, the same is engaged by the conveyor elevatorv I9 andliftedithereby for deposit on an inclined screen 2S. 2. Process for heating dry bulk materials dif fering >in particle size which comprises advancing a stream of materials ’of relatively coarse particle size through a conñned heating zone, simultane ously >therewith ‘advancing’ a `second stream of such materials possessing a iiner particle size through a separate heating zone, bringing the heated materials discharged from said'zones finto direct heat-exchanging and preheatingrelation The mesh of this screen is ship with the unheated materials undergoing such that as the mixture passes thereover, the calcined lime of fine particle size will pass through 30 charging advancement to said zones, and screen ing the preheated zone-charging vmaterials from the screen for delivery to storage as a finished the finally heated'materi'als prior to the intro product, while the preheated coarse limestone duction of said charging materials into their >re will be discharged from the lower end of the spective heating zones. screen 2Q into the inlet chute‘of the kiln 2. Thus, by utilizing the dual kilns, each handling 3. Process for heat treating loose bulk granular limestone of determined particle size and differ ing from that handled by the other, I am enabled to obtain thermal eñiciencies and economies sub stantially in excess of systems now in general materials dii'îering in particle size which com prises advancing a stream of 'such materials com posed of 'relatively large or coarse particles uselfor the purpose set'forth. through a heating kiln, simultaneously therewith 40 advancing a second stream of such materials Thus the hot lime, while it possesses its high est temperature, and immediately upon its dis charge from the kilns, is brought into intimate admixture with the charging limestone, usefully possessing relatively smaller Íand finer particle size through a second heating kiln, bringing the ñnally heated materials discharged from each ci said kilns into directheat exchanging relation absorbing’the heat of the lime and minimizing ‘ heat losses in a system of this kind. Another ship with the previously unheated charging ma terials undergoing delivery to each of said kilns, and following such commingling of the heated advantage accruing from the dual and reversely and unheated materials, separating the charg disposed kilns is the fact that combustion air, ing materials from the finally heated materials used in sustaining fuel combustion, may be ef fectively preheated in the gas outlet stack of each 50 and delivering the preheated charging materials to their respective kilns. kiln and by a short transfer line delivered to 4. Process for burning limestone, comprising the-fuel burner of each adjacent kiln. If the placing limestone of relatively coarse particle dual kilns were not used, the transfer line for size’through a kiln which is maintained at such the preheated air would necessarily extend the temperatures as to effect calcination of the lime full length Vof a single kiln, and heat losses there stone, simultaneously therewith passing lime fore would be such as to render the air-pre stone of relatively fine >particle size through a heating element ineiiicient. second kiln maintained at calcination tempera As shown in Fig. 2, the bottom of the heat tures, admixing the hot calcined lime of coarse' exchanging pits, in which a bed of heat-exchang 60 particle `size immediately upon itsv discharge from ing lime and limestone is maintained, may be said ñrst kiln with quantities of unheated lime funnel-shaped to> maintain intimate ' engagement stone of ñne particle size and which servesas the between the hot lime and limestone, and the charging material for the second-named» kiln, restricted outlet 2i of the pit may be arranged subjecting said admixture to a screening opera immediately over the table of a vibratory feeder 65 tion to remove in'a separated state the preheated 23, by> which the heated materials maybe fed'by limestone of ñne particle size, delivering such a controlled feed to the elevator. preheated fine limestone to the inlet ofthe sec ond-named kiln, admixing with the hot calcined invention provides a system or mechanical proc lime of iine particle size discharged from said ess whereby hot burned lime, discharged from 70 second kiln with bodies of unheated limestone each of two rotary kilns placed in adjacent order of coarse particle size», screening said last-named with their material-receiving and discharging admixture to remove the calcined lime of fine ends reversed, acts as a preheating medium for particle size therefrom, and delivering the _pre-_ In summary, it will be evident that the present the cool limestone charged to each opposite kiln, and whereby the ñue kor-stack gases >of each ofthe heated coarse limestone to the inlet o‘ffsaid'ñr‘st named kiln.A . l ‘ . l 2,410,230 6 5. Process for heat-treating loose bulk mate rials, which comprises advancing a stream of such materials composed of particles relatively coarse in size through a confined heating zone, simultaneously therewith advancing a second stream of such materials composed of particles of finer size -through a separate heating zone, admixing with the hot coarse materials im mediately upon their discharge from the first 6. A process of heat treating materials as de ñned in claim 5 and wherein the material streams advancing through the separate heating zones move longitudinally in opposite directions with respect to each other. 7. A process whereby hot burned lime dis» charged from each of two rotary kilns placed in juxtaposition with their receiving and discharge ends reversed, acts as a preheating medium for named heating zone quantities of unheated ma-- 10 the charging limestone of each opposite kiln, and whereby simultaneously the llue gases of each terial of fine particle size, the latter constituting of the two kilns so placed acts as the preheating the charging material for the second heating element for the fuel and intake combustion air of zone, following heat exchange between said ad" each opposite kiln. mixed materials screening the same to separate 8. In combination, a pair of juxtaposed, cylin-v the heat treated materials of coarse particle size 15 drical kilns disposed with the material receiving from the preheated liner materials and deliverend of one kiln adjacent the material discharg ing the latter to said second-named heating zone, ing end of the other, a fuel burner of the blast admixing with hot materials of ?lne particle size type at the material discharging end of each immediately upon their discharge from the said second-named heating zone quantities of un» 20 kiln, a stack at the material receiving end of each kiln, and an air conduit in heat exchange heated coarse material to preheat the latter ma - terial, prior to its delivery to the inlet side of the first-named heating zone, and screening said last»` named admixture to remove therefrom the heatedr relation with the gases passing through the stack of each kiln, said conduit delivering air directly to the burner of the other kiln, whereby such air material of fine particle size and delivering the 25 is preheated, and travels over a relatively short path. preheated material of coarse particle size to the WARFORD A. REANEY. first-named heating zone.