US2240757A - Apparatus for heat treating coal - Google Patents

Description

"/May 6, 1941.

A. G. BUCK APPARATUS FOR HEAT TREATING COAL Filed Maron 2, 1937 :s sheets-#sheet 1 INVENTOR ATTORNEYS 1D A m JDJ :il

lNvll-:NToR i Y- ATToRNEY' May 6, 1941.l A. G. BUCK APPARATUS FOR HEAT TREA'TING COAL Filed March 2Q 19:57

May 6, 1941- A. G. BUCK 2,240,757

APPARATUS FOR HEAT TREATING COAL l v Filed March 2. 1937 3 sheets-sheet 5 f//f/f,

lNvENroR Patented May 6, 1941 UNITED sTATEsePA'rENT `OFFICE Arthur Glasgow Buckomerville, N. J., assignor to Charles M. Buck, Brooklyn, N. Y.

Application March 2, 1937, SerialNo. 128,579 'z claims. gol. 20a-137) This invention relates to an improved appa- -J ratus for heat treating coal, and while many features of the invention are of use in connection with heat treatment of coal throughout a wide range of temperatures, the invention is espe,

One of the important objects which the inten-1;

tion has in View is to provide for improved heat treatment of coalsuch as to enable accurate sub jection of the coal to a temperature of the desired value, thus avoiding the detrimental effects of over-heating and the inefficient results of under-ti heating. Y

The invention also has in view making possible the treatment of coal, for example in crushed or granulated form, in a manner to ensure a temperature rise throughout the entire body of rea`clif, piece of coal to the temperature value desired, whereby to avoid mere surface heatingv of the particles or pieces which, in accordance with. prior practice,rfrequently involves an undesired. rise in temperature at the surface of the pieces; and a temperature interiorly of the pieces lower than it should be.

As already indicated, the invention, and more especially the featuresr thereof mentioned above, is especially useful in the treatment of coalat a;l temperature approximating. the point of thermal decomposition, i. e. that point at which exothermic reactions begin to take place. This point, of course, varies withl different types of coal. For example, the thermal decomposition point; Y for lignite is in the neighborhood of about 4009 F.; for some bituminous coals in the neighborhood of 480 F.; and for anthracite about 750 F.` For any particular coal the point of thermal decomposition may be determined by tests now well known.

A number of changes of an endothermic character take place in coal when heat treated at temperatures ranging downwardly from the point of thermal decomposition, and more particularly in a range close to but just below that point.

For various reasons, some `of which are disclosed in Buck Patent 1,925,132, issued September 5, 1933, it is of substantial advantage to subject coal to a temperature approximating but just below the point of thermal decomposition, prior tothe time the coal is either pulverized orburnt. To effectively and fully ,bring about the reactions of the endothermic type mentioned above, it is desirable Vto raise` the temperature of the coal Ztoa point very close to thepoint of thermal de- Cil the liberated ones ordinarily being in large part composition and maintainthat temperature for an interval providing time for the reactions to take place. In achieving the desired end, it is also of importance ,to ensure heating of the coal uniformly throughout its mass, and not merely at the surface of the particles.

I 'Ifhe present invention provides a method and apparatus for accomplishing this critical and accurate type of heat treatment. Thus the invention is of especial use in the heat treatment of coal up to a temperature approximating its point of thermal decomposition, although .the invention is also of advantage for heat treatment at lower temperatures, for example for drying purposes.

In the treatment of coal in accordance with this invention to a temperature approximating its point of thermal decomposition, certain occluded gases are liberated, and the invention provides, in effect, for the substitution of inert and nonammable gases for those which are liberated,

fiammable or even explosive.

How the foregoing, together with other objects and advantages are attained, will be apparent `from a consideration of the following description, referring to the accompanying drawings, in

Figure 1 is a vertical longitudinal sectional view of coal treating apparatus constructed in accordance with this invention and suitable for carrying out .the method of the invention;

Figure 2 is a top plan view of the equipment of Figure 1; and Figure 3 is a transverse sectional View, on an enlarged scale, of the equipment shown in Figures 1 and 2. i

In general, the equipment includes a rotating drum to which the coal is fed, and a surrounding heating chamber for applying heat to the drum wall. The drum is shown at 4, one end of which is provided with a circumferential track 5 adapted to ride on wheels 6, and the other end of which is equipped with a central shaft 'l mounted as by spiders 8,the shaft being journalled as at 9 and provided with a driving pulley I0 or equivalent device.

One en-d of the drum (the left end when viewed as in Figure 1) is raised above the other end so that upon rotation of the drum, the coal is caused to move longitudinally therethrough.

At the upper end, a feed chute Il serves to deliver coal, preferably in `crushed form, into the y, drum and at the delivery end `a casing I2 is arranged, providing a discharge chamber having an outlet spout I3.

The heating means for the drum includes a furnace chamber I4 fed by the fuel admission means I5, in which chamber the fuel is burned to produce a heating gas which passes from the chamber Ill proper into the inlet distribution chamber I6. As seen in Figure 2, this chamber I6 is extended lengthwise throughout an appreciable lengthof the drum. A flue oroif-take I1 may be provided at the top of chamber I6.

Chamber I6, and also lthe remaining chambers hereinafter described, as well as Vthe furnace chamber I4, are all preferably-formed-by*built-up refractory Walls, many details of which needgnot be considered herein since they formno part of the present invention per se. In `the brickwork, a heating chamberr I8 is provided Varound the drum 4, this chamber having its walls spaced 3,' pass out the stack 26.

Y Several important features of the foregoing should be noted. In the first place, i-t will be observed that the inlet and outlet ports are lo- -cated substantially opposite to each l other dia- Ilolmetrically -of. the 'drum and ,are distributed throughout an extended length of the chambers .associated with the drum, whereby to distribute the gas around both sides `of the drum and also lengthwise thereof in spite of the fact that the L15; source .of supplyof inert heating gas is in ccm- -muni'caton `.with the distribution chamber I6 only Yin the central region thereof. While the distribution maybe accomplished by the use of inlet .ports or portage of a variety of types, I

from the drum Walls on all sides thereof, and 20 prefer to employ graduated Ports: With those of being substantially closed toward the Ainletend of the drum, as bythe sealing ring #I9 (atnthe left :in 'Figure A1) so as t-o avoid escape-of any substantial quantity of gas from the "heating chamber. kIhe'seal of chamber -I'8 around the other end of the drum need not -`be-as complete,

since vleakage ofgas-at this Ipoint would -result in inflow thereof vinto Y--the interior ofthe drum, to which the vheating gas isultimatel-ydelivered,

as more 4fully brought outv herebelow.

YrIfhe `heating sigas -flows-through -ports 20 from the inlet distribution chamber into the heating chamber AI 8 around-thedrum, and-'itr Yis 4especially to nbe noted that these'portsare located adjacent the top of the heating chamber, and further Athatf the ports (see Figure -2) Yare graduatedinsize from the endsof the heatingchambertowardwthe middle, the ports of larger cross-sectionalarea being located adjacent said ends. Y

.largest ,crossfsectional area positioned adjacent .the tends, of the *.chamher :and diminishing sin v size as thetcentersis .fapproalred Similarly, :the outlet ports 2| .are arranged .to

,25 aid in maintaining the :distribution of .the flow 30 .of the character mentioned, withdrawing of .gases by;means of draft .action .or the rke, :through --coiiduit r2;3, ;resu1.ts;in vs.u bstantiai1-y 1mifo r r n flaw .of .gases :over the drum throughout .the lengththereof In addition, awhile the supply of gas to the inlet distribution chamber I6, and the exhaust ,from .fthe :chamber :2i2 may vbe effected .toward either or both @ends-of .these .chambers Y(in which Y .casefatdiifierent graduation 0f portsvwouldfbefem- Heating gas is Withdrawn from vthe --heating'-40 #mom-m ifprofor *to employ fthe-central location chamber through theoutlet ports 2,I'-Which`com municatewith the Vheating chamber'in va lower portion thereof, preferably below `the drum, -and deliver vinto -an -outlet collecting chamber 22 which, as seen Kin Figure 2, is also extended 45 io. hoirullaandtlltlt Port/.S -bClOW .01 adjacent Vlengthwise of the drum -:throughout Va substantial portion of yits length. The ports 2|' -are-also graduated in size in a manner similar tothe-inlet ports 20. Y Y

Withdrawal ofgases from the-outlet collecting chamber` 22 isieiected -by Ymeans -of aconduit 23 which `communicates Withtthis VAchamber `at a point approximately midwayof its lengthsand which is extended to deliver thedischargedigas tothe casing-I2 to flowtherefrom through thel-55 interior of the drum 4. .At'thecoal feeding-lend, the drum is also provided with a casingL-Zdforming fa gas receiving vchamber having a `seal 25 around the drum, rand Lfurther provided ,with an outlet or stack 26.

V,A Vremovable element .21 serves as a closure for axclean-out opening adjacent to the combustion chamber I4. Clean-out openings '28 are also preferably provided in the front Wall of the brickwo'rk in alignment with the .apertures 20 and 2l (see Figure 2), these openings being provided with removable closures 29.

-In operation, fuel is preferably burned' in the combustion chamber I4 to produce an 'inert (gas, which gas is ,delivered to distribution chamber f5 from which itlflows throughinlet por-ts into the upper portion of the heating chamber. The 'gases then 'flow around the drurnsin-contact with the surfacethereoi'andithence downwardly .illustratedisin :this latter .provides the most ef- ;iectiyeggas distribution- .A A.still moredinportant :advantage ows from the efogf :inletiportsfabove-or adiacent'the top ..50 1 qftooal are periodically 4.brought into contact .with

the drum ysurface and .-,then thrown yout of lsuch contact. VThe surface contact of the coal with `the-.dr1. im wall takes placeonly in alower portion i of xthe drum andviazlittle u p onesidadepending upon .the cjlirection of rotation. The heattransferirem theorum =vitali tothecoal, being ,by con- V- duction, is relatively rapdin itseif ec t. For this reason the A,present invention provides 'for the ,contacting ofthe heatngtgasesrst with theilpper .portion Vof fthe ,drum Cwith which 'the .coal is no tn contact) and serially thereafter with lthe ,lowergportion, of ,the drumsurface v(in the `re- Agian :in whichethe goal `comesin. contact with ,the

drum fina-11),. rests show that a temperature place .from the ,time the gases ,contact with the .drum in the -upper .portion :thereof to fthe-time r --the -gases reach fthe lower .portion of 'the drum wall. This is `vof substantial .advantage Yin ,1avoid "70 -ingover-heatingat the times when ithe :coal particles come-fin directcontactwith .the drum wall.

-U-pon withdrawal of the gases .through the discharge conduit z2:3, ftheir temperature `is still further reduced -sothat `at :the btime @of :admission and out Atlrlroilfh "the outlet I-ports 2il-into the "75 -into-the interior rof vthe rdrum, such leases smet' have a tempenature in the neighborhood of about 450 F. The arrangement is of advantage also in providing for iiow of the discharged gases through the drum, the advantages, in general, u being two-fold-rst, heating of the coal by con-l vection, and second, the surrounding of the coal particles with a substantially inert atmosphere, which latter is important in replacing the 4formerly occluded gases which are being liberated by the treatment. The inert atmosphere further insures against initiation of exothermic combustion, even though the temperature of the coal is being carried up to a point very close to the point of thermal decomposition. Y

Although temperature figures are mentioned above, it should be noted that they are given only by way of example, since different coals and different treatments would require other temperatures. Y

From the foregoing it will be seen thatvery accurate control of the heat treatment of coal is provided in accordance with this invention. The method of applying the heat to the coal is applicable to treatment of the coal for various purposes, as for instance for the purpose of replacing occluded gases by inert gas or for drying purposes, and thus the equipment is useful over a Wide range of treatments. 'I'he degree of control, and the uniformity of heating throughout the mass of the individual pieces of the coal treated, is of especial impor-tance where the treatment involves carrying the temperature of the coal up to a point close to the point where active reactions commence.

The distribution of the gas inlet and gas outlet openings lengthwise of the heating chamber, and the graduation in size of these openings, is of importance not only to provide for gas distribution lengthwise of the drum, but also in avoiding the over-heating which would occur in the central region of the drum, were the inlet area concentrated in the central region.

Finally, it may be noted that the passing of the inert gas lengthwise through the drum (especially in a direction opposite to the movement of rthe coal therein) is of importance in setting up a novel type of heat transfer to the coal under treatment. It will be noted that heat is transferred from the gases surrounding the drum to the drum wall. From the drum wall (interiorly thereof) heat transfer t-akes place to the inert gas flowing through the drum, and, in turn, this heat is given up to the coal. This system of heat :transfer provides maximum uniformity of temperature in the coal being treated.

I claim:

1. Coal treating equipment including a rotatable drum adapted to the feed of coal therethrough, and mechanism for heat treating the coal yfeci through the drum including a chamber surrounding the drum, a source of supply of a heating gas, an inlet manifold at one side of one chamber, an outlet manifold at another side of said chamber, inlet means in an upper portion of the chamber for delivering gas from the inlet manifold to the chamber, and outlet means for discharging gas from `a, lower portion of said chamber, generally diametrically opposite the inlet means into the outlet manifold, the inlet and outlet means being distributed lengthwise of the drum throughout an extended length thereof.

2. Coal treating equipment including a rotatable drum adapted to the feed of coal therethrough, and mechanism for heat treating the coal fed through the drum including a source of supply of a heating gas, a heating chamber surrounding the drum, an inlet distribution chamber and an outlet collecting chamber, all of said chambers being extended throughout a major portion of the length of the drum, means delivering gas from said source to the inlet chamber lat a point intermediate the ends thereof, gas inlet ports interconnecting the inlet chamber and an upper portion of the heating chamber and distributed lengthwise of said chambers throughout an appreciable length thereof, gas outlet ports generally diametrically opposite the inlet ports and interconnecting a lower portion of the heating chamber and the outlet chamber and distributed lengthwise of said chambers throughout an appreciable length thereof, and an exhaust conduit for discharging the gases from the outlet chamber, the exhaust conduit being connected with the outlet chamber at a point intermediate the ends thereof.

. 3. Coal treating equipment including a rotatable drum adapted to the feed yof coal therethrough, and mechanism for heat treating the coal fed through the drum including a source of supply of a heating gas, a heating chamber surrounding the drum, an inlet distribution chamber and an outlet collecting chamber, all of said chambers being extended throughout a major portion of the length of the drum, means delivering gas from said source to the inlet chamber at a point intermediate the ends thereof, gas inlet ports interconnectingy the inlet chamber and the heating chamber and distributed lengthwise of said chambers throughout an appreciable length thereof, gas outlet ports interconnecting the heating chamber and the outlet chamber and distributed lengthwise of said chambers throughout an appreciable length thereof, and an exhaust conduit for discharging the gases from the outlet chamber, the exhaust conduit being connected with the outlet chamber at a point intermediate the ends thereof, the gas inletI ports being of greater cross-sectional area adjacent the ends of the chambers than toward the central region thereof.

4. Coal treating equipment including a rotatable drum adapted to the feed of coal therethrough, and mechanism for heat treating the coal fed through the drum including a source of supply of a heating gas, a heating chamber surrounding the drum, an inlet distribution chamber, both of said chambers being extended throughout a major portion of the length of the drum, means delivering gas from said source to the inlet chamber at a point intermediate the ends thereof, gas inlet ports interconnecting the inlet chamber and the heating chamber and distributed lengthwise of said chambers throughout an appreciable length thereof, and means for withdrawing gases from the heating chamber, the said inlet ports being of graduated size from each end toward the central region of the chambers, with the larger ports disposed toward the ends of the chambers.

5. Coal treating equipment including a rotatable drum adapted to the feed of coal there- .through, and mechanism for heat treating the coal fed through the drum including a source of supply of a heating gas, a heating chamber surrounding the drum, an inlet distribution chamber, both of said chambers being extended throughout a major portion of the length of the drum, means delivering gas from said source to the inlet chamber at a point intermediate the ends thereof, gas inlet ports interconnecting the hers, yWithlthe larger ports disposed ,toward the ends .of the chambers. Y

.6. Equipment for heat treating coal includ- :ing:an elongated drum vrotatively mounted :to provide for ,continuous feed `of :coal .therethrough along .the `bottom ofthe drum, Aand `rmean-s `for ,appl-yingheatito the exterior.. surface of the;drum including .a chamber surrounding the .drum

Ythroughout an exten-ded length `thereof, y:and

:means ,for Y circulating 1a heating gas through .the

fthe chamber to thegeneralhr .diametricallybpposite lower portion thereof, .the `path 10i ;gas c;ow heingasubstantially parallel to ,a planedperpenl'cdieular 5to the axis of the .drum substanv:tially throughout .the length `of the ,heating reha-mberftoprovide contactA of -thesurfaee ofthe drum-.at the vtop with Atheflfieating gas at a higher temperature Athan gat the bottom at all points ,cross sectionally of :the drum throughout the A:length of the heating chamber.

I'7. Equipment for :heat treating coal including a,.rotative1 y mounted drum through which coalisadapted ,to be fed lengthwise thereof for treatment, ;a.he.ating .chamber .surrounding said f.druminlet and `outletports providing for circulating a heating` medium through the v chamber .around the drum in a-,path generally transverse the axis of the drum throughout an extended length .thereof and-in a-direction from the upper iside `.of the drum tozthe lower side thereof, the .outletports being oflsetto one-side of the longi- :tudinal'vertical mid yplane of the drum, and the direction of drum rotation being such as to tumble .the .coal up in the drum 'at .said side of 'saidplane ARTHURGLASGO\V BUCK.

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