US1639417A - Method of carbonizing fuel - Google Patents

Description

Aug. 16, 1927.'

Filed May 24 1926 gri/vento@ Ailatente'd Aug. l' .A l l. *UNITED* STATES PATENT'- 5 bon/ization,

y tions,

result is an increase in tillation products and tars whichv have, generally fc'noacrzw. WALLAGE, or' sAN raANcIsco, cALII'oRNIA.

Imrnon yor vcA/aiaoNIjzINo. FUEL.

application ma irai 24, 192s. serial Nb. insel'. j

This invention relates to methods of carbonizing fuel; and it comprises a process of forming and I removing .volatilizable constit'uents from fuel by lowtemperature carwithl recovery of valuable byroducts and the production of smokeless fuel at the other end, which is at a high temperature' maintained---rby impingement of flame on said charge end, flame gases" being moved through the column in countercurrent whereby a relatively stationary zone of low temperature carbonization is insti- .-tuted and maintained, and thea fuel dischar ed from the hot end is cooled and collecte all as more fully hereinafter set forth and as claimed.

' Bituminous coal contains a large vproportion of h drogen in the form of hydrocarbons and y appropriate'heating methods, as vis well known, gas and oily products can be obtained. In ordinary gas making operaand the evolved vaporsare further broken down by the heat to a large extent. The net the amountof gas and a decrease in the amount of oils; these latter being of the4 aromatic or -coal tar type. Incidentally, high temperature carboniza. tiony gives a greater yield of carbon. It is thereforeresorted to in most coke making processes. By carbonization at lower temperatures ith immediate removalof -disfroml the hot zone the character of the products is quite different. There is less gas and more condensable liquid. With manly coals, oil shales and lignites, this liqui has petroleum characteristics. The liquid contains various oils speaking, a. commercial value depending .on their 'vola'- tility; the more volatile components are Jworth more than the less. In low tempera-v ture carboniz'ation the 'fixed carbon formed is s mokelessto an extent depending upon the' thoroughness of-the carbomzatlon.

uel or coke wherein the material to be care honized which is usually bituminous coal but which may be lignite, wood or other fuel carbonization is at a high temperature the gases A so doing Smokeless fuel formed in this lway is desirablevas a fuel for domestic and manufacturing processes. It may be regarded as a product intermediate the original coal and a true coke., In making smokeless fuel it is usual to ,employlow temperature carbonization and endeavor to eliect a sort of rough fractionation, forming and removing only Ithe more volatile products.

' The present invention relates to a process of effecting low temperature carbonization with formation of smokeless fuel or coke, as

may be desired, with concomitant production of liquid byproducts. be wholly those of low temperature carbonization or may contain some amount of, the aromatic hydrocarbons characterizing high temperature distillation. The Yprocess is flexible in this .respect; it'being possible by slight variation of conditions to obtain products which have undergone secondary decomposition with an increase .-.in the amount of fixed carbon andproductin of aromatic oils. The action requires a certain length of time and if this time be af;

vThese products may forded and only enough heat supplied to keep the action going with all the vapor products at vonce removed to a cooler zone,

nothing/is formed but llow temperature products. With bituminous coal lowin oxygen, oils yof petroleum character are,- formed.

however is of loose friable i y The coke forme character. By cutting the time short, by not removing all thevapors and by other variations of conditions; the` results are y varied. To a certain extent the'amounts of cdndensable oily products formed and of fixed carbon are reciprocal; themoreof one the less of the other.

In most methods of cai'bonization heat lis passed vthrough the material by conduction in `some way, vas in the use of the ordina-ry gas retort. Y In the present invention heat is applied as the sensible heat of hot gases passing through the material, the material and traveling in countercurrent. In

the exothermic actions in carbonization.

With coal and most organic materials car- A bonization is exothermic; that is, if the materials be brought to. a certain 'reaction temperature 'they break down spontaneously with liberation of heat; the amount of this heat being enough tol form the gases and vapors vwhich are vthe products. Sometimes the exotherm'ic 'action is. masked by endo- I am enabled to take advantage of thermic actions and in any event, the actual amount of heat developbd, and consequently the temperature attained, is the algebraicr sum of the true carbonization fheat, radiation losses, heat employed in brin 'ng -mineral matters (ash) to temperature, eat.

consumed 'in vaporizing moisture, etc. etc. The net result varies with the various materials but with most the action is positively exothermic, and with proper apparatus will keep itself alive. lIn the present invention I institute and maintain a moving pervious column, usually substantially horizontal, with one end relatively cold and the other end at as high a temperaturey as itv can be given by'contact with flame burning in an arch just above; the flame gases passing inward andl forward through the moving material toward the cold end. Ordinarily, a flame=of burning gas is usually somewhere around 1800-2000"` F. Flame'gases at this temperature, however, in passing. -through hot carbonized material dropl automatically just'beyond the impingement face to MOO-15000 F. by the endothermic reduction of CO2 Aand H2O.

Such a temperature is, attained inside the column whatever the temperature l.of the flame gases may be. As so far stated, my moving column 'has a relatively low temperature at one end and at point near the vother end has a temperature of 1400-1500 F.; with a discharge face just beyond it at a higher temperature. Under these conditions a certain. temperature gradient is established andmaintained within and along the column. vAt the point where the flame gases are reduced, a fixed temperature i's'established and maintained, with temperatures declining therebeyond to the 'temperature at the point of feed. The adient however is never a straightline an theshape of the actual curved depends, among other things, upon the rate of feed of the particular fuel treated. There is always however an vintermediate zoneA at another rather fixed temperature, that of carbonization, which is generally Aaround 800 F. In this zone the curve of` temperature gradient is 'usually rather flat. vThe fuel passing forward is first dried..and preheated and then undergoes ment' of heat.

spontaneous carbonization with develop- Beyond this point the carbonized material is heated upV to increasing temperatures till it" takes the temperature fixed by the endothermic reduction of CO2 and ILO.v Operating as described, all the actions I desire can be accomplished in a relatively short cylindrical chamber; this chamber ordinarily not having a length exceeding .3 or 4 times its diameter. Inhandling several different coals with an 18 inch horizontal cylindrical reaction chamber of conduit form with a moving'full area Vcolumn of materiahall the actions-I desire were accomplished within the length of 32 inches ;I sometimes within the length of 24 inches. However with certain materials containing considerable moisture, such as peats and certain lignites, the chamber can be advantageously lengthened somewhat at the cool end to reduce heat losses in evaporating moisture. With nearly any fuel the carbonization zone is quite short.;` all the carbonization is accomplished withinl a few inches and the material passed beyond is, or may be, substantially free of volatiles and with all t e gases and vapors passed immediately forward toward the cold end of the apparatus, there is no chance for secondary decompositlon. Wlth cold incommg materials the temperature at the feed end is often around 212 F. Frequently, condensation of moisture maintains this particular temperature at this point. Lignites sometimes carry as high as 40 er cent moisture which requires a .considera leexpenditure of heat to remove by vaporization; that is by ordinary drying. Evaporation of a. pound of water requires several times as many B. t. u.

as are needed to bring it to 212" F. from the ordinary temperature. In applying theA present inventlon to lignite some water is evaporated in the drying zone but the heat consumed is restored by condensation in the cooler zones beyond and by lengthening the conduit toward the feed end and giving it a slight downward inclination the hot water Hows backward against the oncoming material, exchanging heat with it. The niet result is the removal of much-of the water of the peat or lignite as a flowing stream at a. comparatively low temperature. With a horizontal chamber, if it be inclination toward the feed en this not only facilitates removal of condensed water but that of liquid products of distillation. With Such a positive removal of heavy liquids (tars, etc.) the conditions in the cari bonizing zone are affected materially; there" is much less opportunity for secondary car- 'bonization to occur. a Conversely,I if the chamber be given a tilt in the other direction, condensed heavy tars drain back toward the carbonization zone and there is a^production .of secondary carbon, increasing the amount of solid fuel formed and `materially chan ing its character. With this formation o secondary Icarbon comes a change in the oily products. 1

With the feed end of the-reaction cham? ber. sharply inclined toward the cafrboniza-` tion zone tarry products pass in that'dlrection to a grater or less extent and the resultant solid fuel is more of a coky material. By varying the inclination I can in fact produce various `gradati'ons between a ltrue coke anda fuel which is simply, so to speak, defsmoked. With various changes in these twofactors iven a -slight los I I can produce varying dinary heating.

. angle and lent yields lof ammonia'.

l terial under regulated be forced so that the end of the .e forward as vapors with the fixe gases.

iults. Assume for exam le, that -I desire to make'a coke-like fuel rom an ordinary type of lignite high in volatiles andin water but not containing enough fusible mager to make a ,coke by `ordownward slant towiird the feed end with an short downward slant beyond to the water and much of the volatile matter pass on 'beyond the angle in the way previously described. But some high boiling ,tars condensing at high temperatures drainback and are carried back to the carbonizing zone and recarbonized there, at least to some extent., If further, the feed carbonizing zone,` which otherwise is(usually 'fairly defl-Y nite, merges with the high temperature zones beyond, the-secondary carbon is hard and iirm and cements the carbonized material the carbonizing zone,

linto a coke.

The present invention'is applicable to bituminous coal, lignite, brown coal, oil shale and the like. `It may also be used with wood and similar tvegetable materials, such as straw, sawdust, peat, etc.. With vegetable materials, however, the vapors formed' are of acid nature and acid `resistant material should be used at the feed end. With mineral fuels, the vapors are alkaline because ofy the presence of. ammonia, and iron and steel can be used. Inthis connection it may be noted that the present process gives excel- In vobtaining high yields 'of ammoniait is desirable to supplement *the operation as so far described, by a short treatment of the carbonized magas producer condi,- tions. v

lIn practicing the presentl invention, the nongaseous products obtained by distille tion are partly condensed in the 4material and may be drained olf, but in art theyB'go e- "cause'of the presence of vapors of light voils in the lixed gases, it is in general .advisable (to scrub aswell as cool in treating emerging gases for their recovery. f

Iii the accompanying illustratioii I have shown more or less diagrammatically certain apparatus useful in performing the-process of the present invention.

vcentral vertical section,

.material by any suitable stoking'mechanism.

" short wide conduit.

preheat d. Warm materials comin The showing is: a vith `some elements in elevation. 4 l

In the showing, velement 1 lis a reaction chamber which takes the form of a relatively4 It .may be "made of metal or. refractory material. @Brick lined' metal casings are satisfactor At the cold end 2, it is supplied with solid fragmentary This material is usually at the" ordinary temf It may however be warmed or from driers are sometimesused. I .have il ustratv perature.

givingr the conduit a' ed a.feed device 'consisting of a cylinder 3" provided with reciprocatingplunger 4 actuated by suitable means 5. Material is supplied to this feed device from chute 6. -At this end ofthe reaction chamber is provided a drain outlet 7 and vapor and. gas outlet S; the latter communicating with suitable condensing and scrubbing means as well assuetion means, not shown. I also provide the conduit withpipe 9serving for the introduction of water or steam where moistening oi' cooling is desirable. Within the conduit the material moves forward' asia full area column. The column may beI regarded as passing through three zones which I have markedA, B and C respectively. In zone A the material is dried and preheated. At the end 2.of the apparatus the material is frequently moist-vor wet because of condensation -of moisture. The driedpreheated material moving vforward in zone A attains a temperature at which spontaneous carbonization sets in with production of carbonization zone indicatedas' B. With al feed not above a certain speed for each particular material, the boundaries of-B are quitevsharp and definite. At a somewhat higher rate they merge more or less'into the other zones. Sometimes I desire them definite; sometimes not. Beyond B the material travels through yzone (l becoming hotter as it' goes, until it reaches a quite definite temperature just inside the discharge face. vWith a. horizontal reaction chamber, at the discharge end the material often has an angle-of-repose face 10; with the angle of course depending on the carbonized material. In making coke, the column breaks oi' at this face. Whether falling off or broken off, as vshown material drops from this fac-e into a vertical chamber 11. In

`Sometimes I blow draft currents of various kinds through it forone purpose or another, "the draft current'going in through pipe which is provided with supply branche 13 14: and 15 which may serve respectively for air, products of combustion and steam. Any gas formed by the'action of this draft eurrent and not wanted in the operation is sent yto a place of use through conduit 16. Usually here is more than enough gas produced to lfurnish the flamewith the aid of airfrom 17 where this is not the case I provide burner pipe 17 which maA be fed with gas recovered from the pro ucts going away through pipe 8. In so using gas, air may bev fed in ,to form aflame by damper mechanism 18.

The dame burns immediately below'fa heat 4 employed and because of the temperature' of the material .discharged lat face 10,'considera. plus gas.` 'l

able hydrogen and carbon monoxid are formed and aid in producing the required draft gases -andiucreases the available surhis surplus gas may be used for other industrial purposes such for instance as raising steam in a power plant.` In so .doing the hydrogen and monoxid are reburnt at a high temperature, returning the heat to the face 10 and aiding in giving a high yield of-v ammonia.

In the operation of the described device', presuming soft soal is fed in through chute 6, the reciprocation of plunger 4 forces successive portions into chamber 1 through which it moves from right toleft. The cold material coming in condensesiwater, tarry vapors, etc. and these drain 0E throughoutletl 7 for separation elsewhere. Uncondensed gases and vapors go to exit through 8. If the ,material is predried, the amount of moisture here may bel merely that coming in with flame gases and with a-large volume of such\ gases none may.condense. If thematerial-be Wet at 2 it becomes dry' in moving towardv zone- B and when its heat is sullicient it undergoes carbonization in B. Passing beyond B, the material heated up progressively until it reaches ai point just behind face 10 at which there is `a tolerably sharp temperature gradient.

Material fallingv off the end face usually has nearly the flame temperature. This material accumulates. Sometimes I pass a draft current through it to form a little gas; sometimes I vdomot.` Usually I introduce .at least a little moisture lfor quenching and gas vforming pur oses; and particularly where production o ammonia is a desideratum. `The actlon of steam on hot carbon being .endothermic, the use of a draft current containing steam is useful in cooling. In any event the accumulating material is finally cooled and usually quenched. It is removed from the collection chamber by lthe-star feed shown In the present'invention I do not v claim apparatus of the general type of that showny and described, this forming the subject matter of another and copending application .filed May 18, 1925, Serial No. 31,148.

.While I have shown the carbonizing chamber as of uniform cross section, the cross section may be different at differentY points with fuels -expanding or shrinkin .in

the operation. In making compact cokeike' fuels it is in general advantageous to have somewhat of a. taper in the chamber; enough to give some resistance to the lforced feed means.

1. In the production of coke or smokeless fuel and byproducts by carbonization the 'process which comprises establishing and maintaining a moving substantiallyA horizontal' pervious "column of fragmentary solid carbonizable material'in-a chamber of process wihih comprises establishing and maintaining'a moving substantially horizontalpervious column lof fragmentary solid carbonizable material in'a chamber of conduit form as a full-area charge, one end of said column being formed`by'1ncoming relatively cool materiah impinging a flameon the other-end of said column-land transmitting hot llame gases throughsaid column in a -direction counter to the passage of solid jmaterials, whereby a stationary zone of carbonization is estab hed and maintained and cooling and que ching material coming from the flame heated end. i

3. In the production of coke or smokeless fuel and byproducts by carbonization the process which comprises establishing 'and maintaining a moving substantially horizontal pervious column ofA fragmentary solid carbonizable material in a chamber of con? duit form as a full area `charge', vone end of sald column being formed by lncoming relatively cool material, im inging a llame on the other end of said colhmnl and transmitting hot llame gases through said column in a direction counter to the passage of solid materials, whereby a.' stationary-zone of Car'- b' oni zation is`established and maintained, dischargingthe .flame heated mass to form a hot accumulation, and passing therethrough a draft current containing an endothermlc agent so as to cool said mass with production of gas to aid in the formation `of said flame. o 4. Inthe production of coke or smokeless fuel and byproducts by carbonization the i25- tal pervious column vof fragmentary solidv les carbonizable material in a substantially horv izontal chamberV of conduit form as a full area charge, one end of sald column being formed by incoming relatively cool material, impinging a flame on the other. end of said column and transmitting hot flame gases through said column in a direction counter to the passage of solid materials, whereby a stationary zone of carbonization is established and maintained. f

5. In the production of coke or smokeless fuel and byproducts yby carbonization the piocess lwhich comprises establishing and maintaining a moving substantially horizon- Y tal pervious column of fragmentary solid c'arbcnizable material in a substantially horizontal chamber of conduit form as a full e area charge, one' end of said column being formed by incoming relativel cool materiali.

impinging `a flame on the ot er end of sai lcolumn and transmitting hot flame gases through said column in a direction counter tothe passage of solid materials, whereby a stationary'zone of carbonization is established and maintained, discharging the ame heated mass to form a hot accumulation and passing therethrough a draft current containing an endothermic agent so as to cool said mass with production of -gas to aid in the formation of said flame.

6. In the production of coke or smokeless fuel and byproducts by carbonization the process which comprises establishingl and maintaining a moving substantially horizontal pervious column of fragmentary solid y carbonizable material in and occupying the entire cross-section of a substantially horizontal chamber of conduit form with a slight maintaining a moving substantially horizon-y tal pervious column of fragmentary solid carbonizable material inand occupyin the entire cross-section Aof a substantially orizontal chamber of conduit form with a slight upward inclination toward the dischargeend, one end Cof said column being formed by incoming relatively cool material, im-

pinging a flame on the other end of said column and transmitting hot flame' gases through said column in a direction counter to the passage of solid materials, whereby a stationary zone ofv carbonization is estabv lished and maintained, discharging the flameu heated massto form a hotaccumulation and passing therethrough a draft current containing an endothermic agent so as to cool said mass with production of gas to aid in the formation of said iame. A

In testimony whereof, I have hereunto-affixed my signature. .v

GEORGE w. WALLACE.-.

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