US2634198A - Coal carbonization and gasification - Google Patents

Description

PatentedV Apr. 7, 1953 f U "rfE'eDf stirs coALfoAnBomzA'rioN ANDGAsmoATmN .lolif` CfKa'rlbacl, New York, N.`Y.,if"assigrior` to Hydrocarbon Research, 1110;;` New York,"N. Y.; a corporation of New Jersey Application June 11, 1947, Yserial No'rvsssvs:

7 claims; (C1. 1s-197.)

, 1 I'hisfilnventiofrflrelates a process for the lpy` fof solid carbonaceous' material.V Inoneof o petitie aspects, this' invention relates tol i s ifo't ec'arboniati'on andgasificationA d calibonaceons materials, "suchl as coal, ligff'` e, IWlicli is particularly useful" t of A.such fr'nat'erials forV `the 1.. preparat of synthesislgas "lfo [synthesis of hydrocarbons; "oxygenatdl compounds.' and the.

nvegsibif of 'Stud cartonaaeosjmaterian, g

.ii-1,11 trovi? @Oakland the-like i@ s .mixture of `predetermined .13. t. u

oflhe'at involved,`y 'the large'omaSsesV of f handled",` the presence `.in the .material 4such .las 'heavy' oils "andtas1eadi'ng-- ation'of thelarge particles, and other ueh factors have'cornpelled .theuse of com `lieated .processe'sfland apparatus; M a number.- of -ilieat lexehaige steps fr all of Whieh'heat `Jis'waste'd andgthezoverall mciecy'of the elementsfreduced. l Furthermore, in suchtcases,the 'gasffor gasmixture produced :has beeagpf Ereiata/elypoor qualityand it hateniedimca g" este 1ra-pr,@duction to Sedute rlflrirdv offihedesired composition; en. Qtiet'af` hi imitation: is t0 prei/.ideen I .the pvrolysisl of a solid `car- Anetlie biete ffthisinteniipn; is to eroi/ide answerer@ mme@.fotftheirymlvse .0f a cae bonaeeos material.containingvolatile@ compo! nente.;v

maateifl :9019? mftg: @155116. ollplmsf Which; carbonaceonsmaterialinponheating to vaporize thebvolatilecomponents; gleaves r residual carbon.` l. biect sie Meridew improved ihexetermiereactive .or f residual `@erben-fv :n

Stil anotheiifobiect 1ste providesucha processaj.

n 2 .il lbonaeeous materiallcontaiing."volatilizablcol J stitu'ents. y o m l u Other Y objects and 'advantages fof the invetion o will lappear. .ofrom .thelQ-followig- `.descriptiorifanfd claims taken in connection `with l the.Y attachedv I drawing. wherein a o preierred; embodiment of .th 1T r. invention is "shown diagrammaticallv o In...a preferred yspecic. embodimie'ni;' .of`v .th invention, a solidfcarbonaceous material fis ,gasi-r ed .by .a novel method. vvherein 'the heatv -foi-l @the necessary carbonization and [gasification is prol. i duced from the material,itseltheheat exchangey` phases beingA carried,outin =`a manner wheretiyiv.. sub stantiallyv all; the.. heat. is j conserved and putlf to eicient luse..` The...v o1atile. corrifnonents'zmfsiioh. .L astar,V oil,` and.. coal `gas :are volatilized in la par. l, V

' bonizingtstep by a highly eflicienttransfer off is rprovideQ-an VVimprovedf.35.V r-thefcarboniaation 10f, e .Carbonaous' heatrrom the actuav gasifyingrstep, s;oeh!volatile,Uv components beinghkjkept outof physical contac'tg` with the material being gasedto avoid contarni-i. nationvlland `interfererice with the productioncf the final. .product gas;- .The oarbonaceous Ifnate-. rialfin nelyjdivided. form .dispersedfdnfa o gaseous medium and-,subieeted t@ @flashen- 2 bcnization; the' heat therefor -Kbeing-- suppliedtbyvfoxidation. of residual cokel from V4thecrarlz'onizaf o tionf.. Theentire process including .the carbon.v ization and` thev gasiiication is carriedout'ina! single reactor, means being provided-forfsepa-o rating-.the operatonsromone anotherwtojprevent mixing of theseveral .gaseous products produced fthereby.-.- o l o v H r y In. brief, in a preferred specic..embodi ment, l the .present invention. contemplates ther maintef` ,.,f nance j of a mass of i-.devolatilized orcarbonizedj material,l for example, coke; .preferably in ther .V1 form of a uidizedimass; in contactar/ith agreact-A` antigas or gases .whereby the carbonized mate- 3:.- rial is .gasied with the..generation of heattto.

produce the desiredgaseous products,l themate rial being arranged in indirect heat .Aexchangei.. relation. with anA incoming. mass .of fresh carbo o naceous material containing :volatilecomponents` Wherebywthe "heat fgenerated byf the 'gasicationi f of the. carbonizedor devolatilizedv material. `is r :4 made' available lWithout substantial .loss :to theV .1

fresh material to eiectlthe'distillationfofythe.fv

volatile.v vcomponents therefrorrifthese 4volatile f components beingsseparately Withdrawn to Y.a'voidv -mixing-svth the.V gaseous preductsofIgasiiication.1

Preferablm the;` fresh fcarbonaceous :materia-1 ein fr.

the-,formof la iine powder is suspendedfin .a non i oxidizing gas, suitably recycled coal gas, and 'con-5fveyed` .through aA heat exchangedeviceyheated :by

thefmass loflcokebei'ng. gasied, the. residualA soli heated fresh material being discharged in the form of coke into a separator, also receiving heat from the reacting zone, wherein the gasified volatile components are separated from the coke. The separator is arranged to discharge the gaseous volatile matter in a manner to avoid mixing with the gases from the gasifying zone and to discharge the resultant carbonized material or coke into the fluidized mass of coke already in the gasification zone of the reactor. To minimize mixing of the products of gasification with vapors of volatilized components from the carbonizing step, the solids in the outlet of the separator and the level of the coke mass in the gasification zone are arranged so that there is a substantial resistance to gas flow therebetween. The gaseous reactant or reactants fed into the fluidized mass of coke may be of any desired type Which Will react therewith exothermically, e. g., oxygen or hydrogen. Limited proportions of endothermically reacting agents, e. g., steam or carbon dioxide, may also be introduced but care must be exercised to ensure that the gasification step as a whole is sufciently exothermic to provide the heat requirements of the carbonization step. Where synthesis gas is the desired product of gasification, the proportions of carbon monoxide and hydrogen in the product gas may be varied by the proportions of oxygen and steam used.

Referring to the drawing which is to he understood as illustrative and not limiting of the invention, a reactor II is provided with a iiuidizing section I2 and a separating section I3 of enlarged cross-section to reduce the velocity of the gases and thus facilitate the separation of coke particles therefrom. A standpipe I4 is connected to a line I5 for discharging hot coke into a stream of recycle gas or similar gas. Steam is bled into standpipe I4 through pipe IIIA to vkeep the solids therein inV a free-flowing condition. A gas inlet I6 supplies an oxygen-containing gas with or without additions of carbon dioxide and/or steam to the base of the reactor to effect uidization and gasification. The carbonaceous material to be treated, such as coal, lignite, and the like, preferably in the form of a fine powder, is charged from a hopper II into a line I8 and fed upwardly through a heat exchange element I9 into a separator 2l, suitably of the cyclone type or the equivalent, in the top of the reactor. A recycle stream of coke from line I4 carried by recycle gas from line I5 may be fed through line 22 to assist in preventing agglomeration of the coal particles during devolatilization and in supplying heat to the coal particles. Separator 2I is formed with a gas outlet 23 and a discharge conduit 24 for solids. An outlet 25 is provided for the gaseous product of gasication and an outlet 26 for product coke in reactor I I. A filter element 25A serves to remove entrained solids from the gases leaving by way of outlet 25.

In operation, the carbonized carbonaceous material or coke is uidized in section I2 of reactor I I by gases introduced through line I6. For such uidizing, it has been found that satisfactory results can beV secured with coke particles of less than 40-60 mesh in size, preferably about 40 to 50 per cent of the particles finer than 200 mesh in size, and a gas velocity of about 0.5 to 3.0 feet per second. The flow of gas is so arranged that the level of the coke extends above the discharge port 24 of the separator for a purpose to be later described.

The oxygen-containing gas, preferably at least 95 per cent oxygen, reacts exothermically in the '4 reactor to produce carbon monoxide. The addition of steam leads to the generation of Water gas, i. e., hydrogen and carbon monoxide, the composition of the nal product being variable by varying the proportions of the gases fed in accordance with the well-known practice.

The product gas is taken oi through line 25 and conducted to storage facilities, a synthesis reactor, or any other desired point. Product coke may be removed as desired through line 2B. Gasication may be carried to any desired extent including substantially complete consumption oi the carbon in the residue from the carbonization step; otherwise, high-ash coke may be withdrawn from the gasification zone for treatment in a separate zone.

Fresh powdered uncarbonized material, preheated, if desired, is fed from hopper Il' into line I8, the material being caused to travel through line I9 by reason of the gas fed through line I8. Line I9 constitutes a heat exchanger entirely surrounded by the reacting coke, and hence directly heated thereby without the possibility of any loss of heat in the transfer. Line I9 may be in the form of a spiral, a series of tubes, or any other suitable form, it being desirable that the maximum heat exchange surface be provided consonant with the rate of flow of the material conveyed therethrough. In passing through line I9, volatile components such as Water, coal, gas, tar, etc., are distilled from the material, leaving coke. rIhe volatile matter, together with coked fines from the mass, is separated from the residual solid material or coke in separator 2I and discharged through line 23 to suitable recovery means.

While the material in line I9 is heated bythe surrounding fluidized mass, it can be considered to be in indirect heat exchange relation with said mass by reason of its being maintained separate therefrom as regards physical contact, the volatilized constituents likewise being maintained out of physical contact with the iiuidizing mass or the gases discharged therefrom.

The coke collects in the bottom of the separator and is gradually fed into the fiuidized mass in the gasification chamber I2 through conduit 24 at a rate generally corresponding to the rate of consumption of the coke in the fluidized mass, the feed being substantially automatic. It will be noted that While the coke in the bottom of the separator and the coke in the gasifying section I2 are of substantially the same density per se, the fluidizing of the mass in section I2 tends to decrease the effective density in section I2, thus creating a pressure differential operating to cause coke to flow from the separator into the major body of coke in section I 2. Because of the resistance to gas iiow oiered by the relatively packed char in conduit 24, it is difficult for the gases introduced through line I6 to pass into separator 2I or the volatile material distilled in line I9 to escape into sections I2 and I3 of the reactor to become mixed with the product gas or enter into reactions therewith.

By feeding fresh carbonaceous materials to the apparatus at a suitable rate, depending upon various factors, such as the cross-sectional area of lines I8 and I9, the material charged into line I8 may be so treated in heat exchanger I9 as to be in a substantially carbonized condition and ready for reaction with the oxygen and steam in the gasication chamber When it is discharged from line I9 into separator 2 I.

By means of section I 3` being of enlarged crosssection relative to section I2 there is a considerlthroughlline;235.

wel@

separatedjiby..llter515A "from Athe v'gases 'leaving 'L'.Byreasono'the conveyance of the fresh ma- *terialthrough line i9 with a 'gaseous"medium,fthe .caibonizatiori lis effected Ain a Widely ldispersed phase which "is in rapid motion. high velocityiinsures an `effective transfer of heat rece'ived from "the surrounding fluidized mass of coke; accordingly, there Iisfflittle or no chance for agglomeration rinline i9 regardless of the vOriginal volatilecontento themate'rial It -will also be notedthat the coal gas and ithervolatile's are in contact'with thesolidl-maiteiiiallfor only a short period of time, thereby enabling a minimum of cracking or degradation 'oi 'these products.

With Aa'bed depth "in fthe .gasification section of aboutflljffeet and an overhead gas space about 5 feet. deepand a temperature `in the .range of about Iiii0`0-l'600i within pipe Iljt'he coking of fthe resh'teed .-inline 1B, when 'in inely divided ffc'rni, can"be accomplished in a travel or residence'tin'ie of about 1 to 4 seconds. In such case, the temperature of the iiuidized bed in the reactor is maintained in the range of about I300-1800o F., dependent upon the rate of travel or residence time of the fresh material in line I9. Obviously,

the temperature as well as the travel time and the rate of flow of the fresh material will vary with different type of carbonaceous materials.

u The present invention requires only a single reactor and a minimum of external piping through which heat may be lost. No difliculty is involved in determining the correct coal grind as with the conventional two chamber design and the problem of agglomeration is substantially eliminated. In cases'where more heat is generated in the gasification step than is required for the carbonization step, the excess heat may be recovered in useful form, for instance, by making vsteam in coil 21 or equivalent heat exchanger disposed in contact with the carbon-containing bed which is being exothermically gasified. Alternatively, excess heat may be utilized to crack a heavy hydrocarbon fraction, say gas oil, introduced through line 28 and distributing nozzle 2-9; this method of utilizing excess heat is particularly appropriate where a carburetted Water gas is the desired gaseous end product of the gasication step.

In the treatment of oil shale and like material containing a large proportion of relatively inert material of the same waste character as coal ash, suitable means is provided for the removal of the waste material such as separators in the product gas lines or a solid discharge outlet in reactor II.

An important field in which my invention finds application is the manufacture of city gas. In such instance, synthesis gas produced in the gasication step is reacted in the presence of a catalyst to form methane which is mixed with coal gas from the carbonization step to yield the desired city gas.

Where the term carbonaceous material is employed herein, it is intended to include coal, lignite, oil shale, brown coal, and the like, containing varying proportions of volatile constituents which, after distillation, leave a solid carbon-containing residue that is capable of reacting with an oxygen-containing gas or hydrogen at elevated pressure in an exothermic mannel?.

bviously., many lvitimut dep bmg *frei-n tu 't and seppe ntiierjsfancijzrriiy en nations sneiidbe "rmpqsecifas are'inmcateufintrie'appended claims.

.I claim: u

l1. fa process v'for "'cabizing and gasifying a s qud carpen'aee'u'sjfastener cbntaing'voiatii- :natie sentiments material is "subacted ieca'rfbonizatin ty 1 -.ire cistiiiatin 'or veianuzebie constituents thre'frmfin a distillation zone and the resulting c'arbenized`iriatriiall is subjected@ gasieanen with an'oxygn-cdntaining .gas in a gasification. zone. the improvemen-t which comprises 'passing said carbonaceous Vmaterial lin lfinely divided fofrm as lfa ndispersed phase entrained lin a stream oi' nonoxidizing 'gas iioiili-ngat 5a velocity sunicient to inhibit vsettling of said carbonaceous material ltherein through the y.distillation *zoney in indirect uheat exchange with a reacting dense .phase fluidizedmass of the carbonized material undergoing gasiaiication "in the gasicationzene whereby -heat required for lthe 4carbcnizaticn transferred-from the gasication zone to the distillation zone, separating the resulting carbonized material from gases comprising volatilized constituents from the solid carbonaceous material, introducing at least a part of said carbonized material into the gasification zone, and separately discharging the gases from the distillation zone and from the gasification zone.

`2. A process as dened in claim 1 wherein carbonized material from the gasification zone is suspended in non-oxidizing gas in admixture with said carbonaceous material supplied to the distillation zone.

3. A process as defined in claim 1 wherein said carbonaceous material is coal.

4. In a process for carbonizing andv gasifying a solid carbonaceous material containing volatilizable constituents wherein said material is subjected to carbonization by the distillation of volatilizable constituents therefrom in a distillation zone and the resulting carbonized material is subjected to an exothermic gasification reaction with a reactant gas in a gasification zone, the improvement which comprises passing said carbonaceous material in finely divided form as a dispersed phase entrained in a stream of non-oxidizing gas flowing at a velocity sufcient to inhibit settling of said carbonaceous material therein through a distillation zone contiguous and in direct heat exchange with a reacting dense phase uidized mass of the carbonized material undergoing gasification in a separate gasification zone whereby heat required for the carbonization is transferred from the gasification zone to the distillation zone, separating the resulting carbonized material from gases comprising volatilized constituents from said solid carbonaceous material, introducing at least a part of said carbonized material into the gasication zone, and separately discharging the gases from the distillation zone and from the gasication zone.

5. A process as defined in claim 4. wherein carbonized material from the gasification zone is suspended in non-oxidizing gas in admixture with said carbonaceous material supplied to the distillation zone.

6. A process as dened in claim 4 wherein the exothermic gasification reaction is carried out with hydrogen at an elevated pressure as the reactant gas,

'aesaifols 7. In a process for lcarboriizing and gasifying a solid carbonaceous material containing volatilizable constituents wherein said material is subjected to carbonization by the distillation of volatilizable constituents therefrom in a distillation zone and the resulting carbonized material is' subjected to an exothermic gasification reaction with a reactant gas in a gasification zone, .the improvement which comprises passing said carbonaceous material in finely divided form as a dispersed phase entrained in a stream of nonoxidizing gas flowing at a velocity sufficient to inhibit settling of said carbonaceous material therein upwardly through a distillation zone disposed within a gasification zone containing a reacting dense phase fluidized mass of the carbonized material undergoing gasiication whereby heat required for carbonization is transferred by indirect heat exchange from the gasication zone to the distillation zone, introducing the resulting carbonized material and gases comprising volatilized constituents from the solid carbonaceous material into a separation zone disposed within said gasification zone and having an outlet for solid carbonized material disposed within said fluidized mass of 'carbonized material whereby carbonized material from said separation zone is introduced directly into said fluidized mass in said gasification zone, withdrawing said gases comprising volatilized constituents and substantially free from carbonized material from said separation zone, and separately discharging the gases from the gasification zone.

J OHN C. KALBACH.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 2,248,196 Plummer July 8, 1941 2,285,276 Hemminger June 2, 1942 2,341,193 Scheineman Feb. 8, 1944 2,378,342 Voorhees et al. June 12, 1945 2,428,872 Gunness Oct. 14, 1947 l2,445,327' Keith July 20, 1948

Claims (1)

1. IN A PROCESS FOR CARBONIZING AND GASIFYING A SOLID CARBONACEOUS MATERIAL CONTAINING VOLATILIZABLE CONSTITUENTS WHEREIN SAID MATERIAL IS SUBJECTED TO CARBONIZATION BY THE DISTILLATION OF VOLATILIZABLE CONSTITUENTS THEREFROM IN A DISTILLATION ZONE AND THE RESULTING CARBONIZED MATERIAL IS SUBJECTED TO GASIFICATION WITH AN OXYGEN-CONTAINING GAS IN A GASIFICATION ZONE, THE IMPROVEMENT WHICH COMPRISES PASSING SAID CARBONACEOUS MATERIAL IN FINELY DIVIDED FORM AS A DISPERSED PHASE ENTRAINED IN A STREAM OF NON-OXIDIZING GAS FLOWING AT A VELOCITY SUFFICIENT TO INHIBIT SETTLING OF SAID CARBONACEOUS MATERIAL THEREIN THROUGH THE DISTILLATION ZONE IN INDIRECT HEAT EXCHANGE

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