US 2662007 A
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Dec; 8,-1953 N. L. DlcKlNsoN cAsIFIcATIoN oF PowDEREn cAxING TYPE coAL Filed June 2. 1947 l .'5 Sheets-Sheet 1 Dec. 8, 1953 N. L, DlcKlNsoN GASIFICATION OF POWDERED CAKZINGv TYPE COAL s sheets-sheet 2v Filed June 2. 1947 INVENToR.
NUHMA N L. UGH/MSDN 6.5K MMM-.AL
Dec. s, 1953 N DICKINSON 2,662,007
GASIF'ICATION OF POWDERED CAKING TYPE COAL 7 Trams/@ Patented Dec. 8,` 1953 GAsIFlcA'rIoN oF PowDERED canino TYPE ooAL Norman L. Dickinson, Basking Ridge, N. J., as-
signor to TheM. W. Kellogg Company, Jersey City, N. J., acorporation of Delaware e Application June 2, 1947, serial No. 751,728
rThis invention relates to the treatment of carbon-containing material. In one vaspect this invention relates to the high temperature treatment of solid carbon-containing materials, such as coal and coke. More specifically, in one aspect this invention relates tothe production of a gas rich in hydrogen from coal or other solid carbon-containing materials.
- It has been known 4for some time that coal maybe treated with oxygen and steam at relatively high temperatures to convert the coal to hydrogen and carbon monoxide,v which products are useful for the synthesis of organicV compounds. In general, coal, coke, 4or other carbon-bearing solid materials are-contacted with oxygen and steam in an amount of about cubic feet of oxygen per pound of steam per pound of coal at a temperature aboveabout 1000 F. under conditions such that the carbon, steam, and'oxygen are converted to hydrogen and carbon monoxide. rVarious methods have been practiced to eiiect the gasiiication of coal to produce a gaseous eiiiu-` ent rich in hydrogenv and carbon monoxide. Among these methods is that known as the Lurgi process, which comprises countercurrently contacting a `moving bed Aof crushed or ylump coal with an upward flowing mixture of oxygen and steam. A temperature vbetween about 600 F. and about l600 F. or--higher is maintained between the top and bottom, respectively, of ,the moving bed of coal and apressure ofl about 200 or 300 pounds per square inch gage is maintained during the gasiiication process. This processis v characteristic of producing a gaseous eflluent containing hydrogen, carbon monoxide, and considerable quantities of carbon dioxide and methane.
Also, among these known methods for the gasif iication of coal is the Winkler process which com-.- .prises passing oxygen and steam through a socalled fiuid bed of finely divided coal at ay temperature of about 1600 F. to 1800 F. and at about atmospheric pressure or slightly above. The Winkler process is characterized by an operation using a pseudo-liquid dense phase of coal achieved by passing a gaseous mixture upward through pulverized coal having a size of. about 0.5 inch process has several apparent advantages over other processes, such as the moving bed type operation. One of these advantages is the fact that the-Winkler process or uid-bed process produces hydrogen and carbon monoxide with only minor amounts of methane, which fact is desirable when the product is to be used for the synthesis of hydrocarbons. Even in view of the relatively good results obtained bythe iiuid-bed type operation, certain inherent disadvantages have been found. In such iiuid-bed roperations in which the ly divided suspended'coal and maintain the nely divided coal continuously in a iiuidized condition. The sticking or caking of the coal particles limits the use vof the` Winkler processto special grades of coals which do not have this tendency to stick at high temperatures. It is desirabletherefore, to provide a processand apparatus which overcome'these difliculties. f t Anobject of this invention is to provide a proc-` ess and apparatus for the gasiiication of carboncontaining'solid materials.V n NAnother object of this invention is to provide a process forthe production of hydrogen from carbon-containing solid materials.
Further, another object of this-inventionis to provide a process for the production of coke from coal. v v f 'It is a further object of this invention `to pro.- duce hydrogen-and carbon monoxide from coal.- `Yet another object of this invention is to produce a gas `of relatively high heating value. Still another object of this invention is to pro- 'vide a method for the' recovery of volatile comin diameter such that the pulverized coal is suspended in the gaseous mixture under the conditions of operation. In the Winkler operation a relatively low upward gas velocity characteristic 50 of .that necessary to produce a pseudo-liquidflmd- It is an objectY to provide'a coal gasication' in hydrogen and carbon monoxide by suspendingv or ent-,raining finely divided solidmaterialcontaining carbon in a stream of oxygen and steam. at relatively high temperatures and high prSr.
sures. According to this invention, finely divided coal is introduced into a rapidly flowing gaseous' stream of oxygen and steam under conditions such that the heaviest particles are continuously? 1 moved by entrainment in the direction f fio wA Y 4 pass. The reaction zone should be of such length with regard to the gas velocity that sufficient residence time is provided for substantially complete gasification. However, the reaction zone may be of such length to provide insufficient residence timefor complete gasification of the coal in one pass, and in such case unconverted coal is recycled to the reaction zone to complete the gasification thereof.
Various solid carbon-bearing materials may be employed and Can'be converted to hydrogen and 'carbon monoxide according to the techings of thisliiiyention.l Such carbon bearing materials compriseivaroustypes of coal, such as anthraof the gaseous stream. The linear velocity'of the ditions o f velocity,` the conventional pseudo-liquid or fiuidized dense phase of nely dividedparticles is not formed but instead a dilute phase of finely divided and highly dispersed particles is produced which permits much higher temperatures of reac-` tion than heretofore possible with conventional nuid-bed type operations using comparable quality coals.v Pressures from about 100 to about 1000 pounds per square inch gage and temperatures from above about 1400 F. to about 2600o F. are employed. At the high gas velocities and degree of dispersionof the coalY and this inventiomsubstantially complete conversion of the carbon to hydrogen' and carbon monoxide can be effected at A high temperatures without agglomeration.
bite, -bituminous,` sub-bituminous, lignite, and
various types of coke, such as coal coke and petroleum/coke; Poor grades of coal may be used in this process because little opportunity is aforded for agglomeration of the coal particles at suchhigh velocities andA at such low concentrations encountered in the process of this invention. Furthermore, since the tendency of the carboncontaining materials to agglomerate or fuse in the reaction zonev is practically eliminated, relatively higherV temperatures can be used, if desired, than in other conventional coal gasification processes. For example, at pressures above about 25() pounds per square inch gage and at temperatures above about 1800 F., a gaseous effluent containing hydrogen and carbonmonoxide substantially' free from methane is obtained. Such a gaseous effluent is highly desirable for subsequent use for theconversion thereof to organic compounds by various known synthesis processes'.
For the gasification ofk coal or other-solid carbon-containing materials according to the present invention, the coal must be in a finely divided powdered form. yPreferably, the powdered solid material initially contains no more than a minor Operationsaccordingto this invention also en able a large capacity per unit volume of sizeof equipment. Methane can be'produced together with hydrogen and carbon monoxide according to .one embodiment'of the present process by, us;- ing temperatures lower than. 1800" F. andas low 21.5.. about 1000 F. IIhus, when it is desirable to producemethane along with. hydrogen and. carbon monoxide, such as for fuel purposes, this rnay be done conveniently by regulatingthe temperature along Vwith such other conditions as resi@ dence time of the coal andthe ratio of steam and oxygen.
Generally, the ratio of oxygen to coal, and steam lto coal may be varied from about 4 to about 15 cubic f eet of oxygen per pound of coal and from about 0.2 to about 5 pounds of steam perV pound of coal, respectively. The proportion of oxygen, steam, andcoal is regulated withinthe above ranges to control the temperatureofconversion and also tovr control theconversion'. of
coal per pass fora given residencetime of coal. As the interaction between steam v'andjcarbon is endothermic and thatbetween oxygen and ca rbon is exothermic, sufficient oxygen must be in troduced into theconversion Voneto maintain the desired temperature of reaction.
Complete conversionor gasiication ofthe coa to gaseous products. when operating according to this process is achieved -by a residence vtimeofthe carbn-containing. material. in the.. reaction vlor proportion by weight of material vwhose average particle'diameter is greater than about 250 microns. Anexample of a desirable powdered coal is one in which about '7 5 to 95 per cent by weight passes through a 200 mesh screen. The pulverizationof the coal may be effectedl by various conventional` means,v such as by grinding in a ball milhas, by conventional equipment known as the Micronizen'or by explosion pulverizetion; without'` departing from the scope of this invention.
Generallyl lthe reaction zone itselfV Will comprise a single conduit ortube of an inside diameter between about 1 and about 6 feet. Preferably, the reaction tube is of sufiicient length withrespeci;` to the velocity ofthe gases therein that substantially complete ge sincation of the carbon- 'containing material is effected in a singlepass andmay containY baffles and/or orifice plates to obtain thedesiredturbulence, especially in the larger diameter reaction chambers.
.This process is distinguishable over those processes which employ affluid-bed typeV operation. In" the fluid-bed type operation, the finely divided solid materialforms a so-called pseudoliquid., dense phase ofsuspended material inthe reaction zone and; consequently the carbonaceous ma te`rial' remains inthe reaction zone itself in thisdense f iuid beduntilgasiiied or converted. The concentration ofsolid material in the dense fiuidbed isY rluch greater than the concentration o1? sclidmaterialin the reaction zoneof this` inf vention. Inthedense phaseY process the conf eentr'ation isusually greaterthan about 1.0,or 20 pounds `of solidA materiali per. cubic foot.. Qf ses .andmay be as high as lOo pounds per. cubieioot of gas atstandard conditions. Usually, in the.:
conventional pseudo-liquid dense phase process, the reaction zone is of such a volume and crosssectional area and the gas velocity is sufficiently low that the nely divided material is suspended in afluid bed with thek presence of a so-called interface 1 of rapidly decreasing concentration between the fluid-bed and an upper dilute phase. The upper dilute phase contains a small amount of ashand unconverted solids as carry-over from the dense phase. Usually only a minor proportion of the conversion, if any at all, is effected in the dilute phase; the dilute phase being primarily Va separation zone for preventing the carry-over of solid material from the dense phase. In the Winkler process, the major proportion of the conversion is effected in the dense phase.
Although the process of ythis invention has been described with reference to an upward owing gaseous stream of steam and oxygen and entrained carbon-containing material, it should be understood that the carbon-containing material and gaseous reactants may flow together downwardly, horizontally, angularly, or with a circular movement through a reaction zone without departing from the scope of this invention. In horizontal, circular, or angular flow the velocity should be sumciently high to cause turbulent flow thereby preventing settling ofthe i finely divided coal.
, In yvertical rlcw, the concentration is a function of velocity at relatively low velocities but as velocity is increased a point is reached where slippage of the solid particles in the gaseous stream is negligible. At velocities above this point, concentration is a function of the loading rate (amount of solids forced into the gaseous stream). Preferably, ythe velocity of the gas is such that slippage of the flnely divided particles of coal is negligible.
The use of finely divided coal of 250 microns or less results in a very high rate of reaction because of the large surface area of the coal particles. The rate of reaction is also increased by high partial pressures of steam and oxygen, by the extremely short time required for the coal particles to reach the reaction temperature as the result of radiant heat transfer unobstructed by high concentration of solid particles,-and also to some extent by dissociation and ionization phenomena characteristic of flames. The high rate of reaction in turn enables a large capacity perk unit volume of size of equipment.
rrThe gasification of coal isveffected according to the-following typical equations: 'y
" CY-l-H2O- CO+H2 2C|O2 2CO ',"As high as 99.5 per cent overall conversion and as' high as 85 per cent, carbon monoxidel yield based'on carbon feed is achieved when operating, a' process within the preferred conditions of this invention. The efiluent from theconversion zone contains on a dry basis about Y30, to about 50 Volume per cent carbon monoxide,
yabout 35'to'about 55 volume per cent hydrogen,
about to about 20 volume per cent `carbon,
dioxide, and about 0.1 to about 25 volume per cent methane.
This invention will be discussed further by reference to the accompanying drawings which comprise viewsin elevation, partly in cross-section, of' suitable arrangements of apparatusfor carrying out l the process of the present ini/'efrtion.` Figure 1 of the drawing is an elevational View, partly in cross-section, diagrammatically illustrating an arrangement of apparatus for the' monoxide and hydrogen,; and diagrammaticallyVv illustrates an elevational view of apparatus,A
partly in cross-section, for suchan embodiment` Figure 4 is a 4diagrammatic illustration in ele-v vation of a modification of chamber |28 of Figure 3.. Figure 5 is still another embodiment ofv the present invention'-diagrammatically illustrating an elevational View of a suitable arrangement of apparatus for the production of hydrogen and carbon monoxide from coal.
In Figure l of the drawings crushed coal is introduced through conduit Il into storage vessel l2. The coal, preferably, is of a size such that it will pass `an -8 to 16 mesh screen. The crushed coal flows from storage vessel I2 through a branched conduit I3 into a series of parallel lockhoppers i4, l, l1, and 18, as shown.' By means of these lock hoppers the coal is raised to a desired pressure for operation of the process. In loclf` hoppers lUl and Il the coal therein is pressured with a gas introduced through conduits 22 and v23.l In these first lock hoppers the i coal is pressured, for example, to a pressure of about 260 to. about 300 pounds per square inch gage. The coalisfthen passed at rthis pressure into the next hoppers, i6 and .18, in which the pressure ofthe coal israised by means of aga-s to about 500 to about 600 pounds per square inch gage, or higher. The pressuring gas is introduced into lock hopperswl and i8 through either conduit 'i9 or` conduit 2l. are Worked'alternately in series; that is, one series is introducing the pressured coal into conduit 32under conditions of controlled flow while the otherrseries is being pressured. vAfter the coal' has been introducedrinto conduit 32 from either of hoppers I6 or i8, for example, hopper I8, the gasesunder the pressure existingin hopper 'i8 arelexpanded into hopper Il in which coal has been introducedf, The coal is then passed fromhopper Yllto hopperl at the pressureA existing ,inv hopper l'l.-Pressuring gas is introduced into hopper I3 through conduit `2i 0r Aconduit, tte raisegjhe pressure -to'the Yde-y continuously injected ,frornkhoppers I6 and '18.
The resulting mixture is conveyedthroug'h conduit 32`ftoa conventional expansion nozzler 34.'
*"In nozzle 34 the steam containing the entrained coal is-I expanded into conduit 36 to a pressure vlowerthan that pressure existing 'in conduit 32, lusually about to :about 300 pounds per square inch lower Vthan in.conduit.32.": By virtue ofthe sudden .expansion ofthe mixture of gases and coal in nozzle 34; ther-gases or liquidin the poresof the coal are also rapidly, expanded causing VPul- The hoppers,
aceaoovif verzat'i'ori f the coal; Some pulverzation may be effected by the impact between particles in the turbulent wake of `nozzle L34. This kexplosion pulverization process reduces the particle size of the coal to a size less than about 250 microns and often less than about 100 microns. For low pressures of conversion. su'icient size reduction of the coal can be achieved with pressure drops as small as '15 or 50 pounds per square inch. The pressure drop across nozzle 34 required to obtain the desired size of coal particles depends on such factors as the desired sizeof the particles, the design of the nozzle, the nature of the solids and expansion medium, ratio of solids to expansion medium, etc. These factors are correlated to give the ldesired particle size.
Natural gas, recycle gas from a synthesis process for producing hydrocarbons and organic compounds from hydrogen and carbon monoxide, or recycle gas from the coal gasification process itself may be introduced into Athe system through line 32 and may serve as the carrier gas for the coal in line 32. Natural gas or recycle gas may be introduced in addition to or alternatively to the steam from conduit 3l and may be introduced and admixed in conduit 32 or may be passed through conduit l33 and admixed with the steam and pulverized coal in conduit 36. IThe mixture of steam, pulverized coal, and any other gases, such as a natural gas or recycle gas, are passed through conduit 36 to a burner 31 and a vertically positioned combustion chamber 38. Burner 31 comprises ai cylindrical chamber in which the gaseous mixture of coal and steam is introduced at one end lthereof and steam and v oxygen are introduced together or separately through a series of perforations or ports through the cylindrical shell of the burner, such as through conduits 52 and 53. The coal-containing mixture, the steam, and the oxygen may be injected tangentially through burner 31 into chamber 38, if desired, in order to impart a whirling motion to the mixture leaving the burner.
In order to gasify the coal, oxygen `is introduced into 4combustion chamber 38, such as through burner 31. Oxygen may be produced in anyconventional manner in oxygen plant 40, such as by refrigeration and condensation of air to separate the oxygen therefrom. Substantially pure oxygen, usually between about 90 and about 98 per cent purity, is passed from oxygen plant 40 by means of compressor 4l through conduit 42 to a conventional preheater '43. In preheater 43, the oxygen stream is heated toa temperature between about 500"` F. and l000 F. Oxygen is passed from preheater 43 through conduits 44, 52, and 53 to burner 31.
When insufficient steam is supplied from "high pressure steam boiler 29 for eifecting the reaction or gasication of the coal in chamber 38, lor for other reason, additional steam may be introduced into thev systemthrough conduit 46. Such additional steam is generally at a lower pressure than steam from boiler 23 and ispassed through a conventional super-.heater 4.1 -in .which the steam is .heated to a Vtemperature between about 750 F. andl'100" Super-heated steam is passed from super-heater 41 through conduits 48 vand 49 to conduit 36 for admixture with the steam and coal mixturetherein. Alternativelyv or additionally, .thesteam `fromzconduit 48 'may .be introduced andadmixed V.with 'the oxygen in vconduit '5 l .as shown, and then passed 'through `conduits 52 :and 53 yizo-burner 31. iPr-ehea-tinglof the reactants reduces the quantity .of oxygen required.
to obtain the desired conversion temperatln'e.
The amount of voxygen supplied `through Lconduits 52 and 53 is between labout 5 and about 15 cubic feet of oxygen .per pound of coal or carbon? bearing material, preferably the amount of oxygen is between about 6 and about 11 cubic feet per pound of coal. The total amount of steam present in the system after introduction through conduit 32 and conduit 49 or in admixture with the oxygen through conduits 52 and 53 is initially between about 0.2 and about 5 pounds of. steam per pound of coal or carbon-bearing material, and preferably between about 0.4 .and about 2 pounds of steam per pound of coal.
Under the conditions in burner 31 the coal is ignited and passes as a `iialne together with the. oxygen and steam from burner 31 into combus tion chamber 38. Combustion chamber 38 comprises preferably an elongated cylindrical conduit or chamber internally insulated with a suitable refractory material substantially resistant to the high temperatures of combustion therein. Com` of combustion chamber 38 is above 1800 F. in'
the preferred embodiment of this invention for the production of a gaseous effluent rich .in hydrogen and carbon monoxide and substantially free from methane. The minimum temperature in the range above 1800 F. required to obtain a product free from methane will depend upon. Under these conditions. of operation and at the high pressures involved" the operating pressure.
the nely divided coal particles are carried along with the upward flowing gaseous mixture without the formation of the conventional pseudoliquid dense phase characteristic of lower velocities. At velocities between about 15 and about 50 feet per second the particles Vof c oal are carried along by the gaseous stream substantiallyat the same velocity -as the Vlinear velocity of the gas. However, some slippage of the solid particles may be evidenced in the vertical cham-. ber 38, but this slippage is usually not much more than about 50V per cent in the extreme cases. Under these conditions of operation the concentration of coal in the gaseous react-ion mixture is Very low, usually between about 0.0-1-
and about 0.5 pounds of Vcoal lper cubic foot of gas at standard conditions of temperature -andpressure. The residence time of the coal in the combustion chamber lis substantially the same as the residence time of the gas flowing therethrough, or at least the residence time of the coal is much shorter than the residence time of the solids in the conventional ,pseudo-liquid phase process. In the preferred embodiment of this invention, combustion chamber 38 is of such length that ,the solid .particles will remain in the chamber a sufficient length of 'time to achieve complete gasification thereof; such times usually being less than about v5 seconds and Aoftenas low as 1 `or f2 seconds. l
As ypreviously discussed, if it vis .desired to produce a substantial `quantity of methane in-.the ultimate gaseous effluent fromcombustioncham? ber 38, lower temperatures are necessary; 'usuall` the ytemperature isbelow about 1800311. and preferably about 1500 F. depending'upon the; operating'` pressure. The `temperature `of reaction is lowered ,by altering the .ratios `of zoxygen `and,`
.or storage tank 12.
steam to coal as previously discussed. A gaseous effluent containing hydrogen, carbon monoxide, small quantities of ash, carbon dioxide, and steam, and in some cases methane, is removed from combustion chamber 38 and passed through conduit 3-9 to a waste heat boiler 5ft which may comprise a single or a plurality of boilers. In Waste heat boiler 54 a considerable portion of the heat is removed from the gaseous effluent and utilized in producing steam which may be used in the process. The reaction eluent is passed through tubes 55 of boiler 54 under conditions such that the eilluent is cooled to atemperature of about 1000 F. or lower.` The cooled eiiluent is then passed from boiler 54 through conduit 56 to a separator 51. In separator 51, ash and any unconverted or partially-converted carbonbearing material' are removed from the gaseous effluent. Separator 51 may comprise a single or plura 'ty or" cyclone separators, a Cottrell precipitator, lters, or other conventional means for separating iijnelyA divided solids from a gaseous mixture. A small amount of ash may be allowed to pass out of separator 51 with the gases. Ash and carbon-bearing material separated in cyclone separator 51 are removed therefrom through conduit 58 and passed to a hopper or storage vessel 59. From storage vessel 59 the ash and unconverted or partially converted coal are recycled or returned to lock hoppers l5 and i8 through conduits 5l and I9 by means of steam introduced through conduit I9. In order to prevent the build-up of the ash content in the system, a portion of the recycled ash and unconverted or partially converted coal may be Withdrawn through conduit B2 for disposal, or means may be provided for separating ne ash from unconverted coal, such as by allowing ash Yto pass overhead in separator 51. If desired, unconverted ash and coal may be recycled directly to conduit 35 and ultimately to combustion chamber 3s through conduits IS, 62, and 63. The ash separated from the eilluent in cyclone separator 51 may be disposed of directly, if desired, and this may often be the preferred manner of operation where substantially all of 'the carbonbearing material is converted to gaseous products. In such a case hopper 50 and its connecting conduits may be omitted.
A gaseous eiiluent substantially free from unconverted or partially converted carbon-bearing material is passed from cyclone separator 51 at s. temperature of about 1000 F. or lower through ponduits 08 of a conventional Water heater 61. Water is passed to water heater 01l through conduit 6% and is heated'under pressure to a tem- .perature of about 400 F. If a pump is installed between heater 61 and subsequent boilers, then the pressure on the .water sideof `heater 61 need be only that necessary to suppressfvaporization therein. The heated water is passed from water heater 61 through conduit 69 to a steam drum If additional water is desired above that needed to cool the eilluent from separator 51, such Water may be introduced into conduit 59 through conduit 1l. The heated water is then passed under pressure from steam drum 12 through conduit A16 for indirect heat exchange with the combustion chamber efuent in zol vfles 84 countercurrentl-y to a downward owing boiler 54. In boiler 54 water is vaporized under Y off heat exchange between ythe eiiluent er the eombustioncharnber ,1. 8 and water, generally substantially all ofthe steam required in the process is produced with the resulting economical advatage of conservation of heat. rlhis steam thus produced is passed through conduits 18 and 19 to conduitl 46 for preheating and introduction into combustion chamber 38, as previously described. Various methods of heat exchange, such as heat exchange of steam and/or oxygen in conduits 46 and i2 with the effluents in conduits 3Q Vor 56, may become apparent to those skilled in the art without departing from the scope of this invention.
The gaseous mixture of hydrogen and carbon monoxide ata temperature of about 300 F. to 600 F. is passed through conduit 8l to scrubbing tower 82. The entire system, including scrubber tower 82, is at approximately the pressure existing in conduit 36 after the expansionof' the coal vand gaseous mixture through nozzled. lIn scrubber 82 the gaseous effluent passes upward through bafstream of water introduced'through conduits 83 and 81. The liquid scrubbing medium removes fine ash entrained in the effluent, which has not been removed by cyclone separator51, and also Afurther cools the gaseous effluent to a temperature of about F. or lower and condenses any Water vapor in the eiiluent. The scrubbingmedium co1- lects in the lower portion of scrubber 82 as indicated by the liduid phase 85. A major proportion of this liquid'pha'se is recycled through 'conduit'81 and cooler 88l to the upper portion of lower portion-of scrubber 82 through conduit 89 v'for disposal oryremoval of the ash therefrom. 'The 'gaseous effluent -novv at a temperature'of about '100 F. or lower is removed from' 'scrubber' 82 through conduit 9i 'and may be passed to storage (not shown)l vor maybev used directly as a fuel, as 'a' feedrgas for the synthesis of hydrocarbons and oxygenated organic-compounds therefrom', or in the production o f"hydrogen. The coal lgasification veffluent contains, besides hydrogen andk carbon monoxide, relatively'srnall amountslof carbon dioxide',v methane; ands'ulfur compounds, such a's lhydrogen sulfide. The sulfur compounds'l are pro'- v-duced'fro'm small amounts of sulfur in the coal.
These compounds present as impurities'may'(`v be removed from-the yeiilfuent by conventional means .(not shown).
l' A portion` of the' Agaseous` eiliuent comprising hy'- drogen andtcarbon monoxide may be returnedl tb "the lock'hopp'ers asa 'pressuring gas or may be used as a conveying'or expansion medium as previously indicated. Recycling in the above manner is accomplished by passing a portion of the gaseous effluent from conduit 9| through conduit 9 2 vto knockout drum03` in vfhich entrained water is separated from the gaseous effluent and removed from drum 93 throughconduit 94. The gaseous mixture substantially* free from entrained liquid is removed from drum 9'3 and passed through con#- duit 95,A to .compressort06.v In compressor 96vthe gaseous eiluentis" compressed to the desired pressure for repressu'ring the lock hoppers. The compressed efluent is thenpassed to asecond drum or accumulator 'S1 in which any condensate formed 'aeeaoov present invention in" which steam is: passed through conduit |2|' and finely divided coke is picked up from conduit |34. The pulverization and coking process in chamber'lZS from which the finely divided coke is obtained will be discussed more fully hereinafter. Coke and steam vare passed at a pressure, for example about 300 bustion elliuent is passed from combustion chamber |23 through conduit |21 to the lower portion of a second enlarged chamber |23which is positioned vertically. Crushed coal is introduced into hopper |36 through conduit |31 and is pressured by a gas introduced therein through conduit |38. Hopper |36 may comprise a series of lock hoppers, in accordance with the description of Figure 1, in order to maintain the coal at the desired high pressure. .Coal under a pressure of Vabout 500 to about 600 pounds per square inch gage is passed from hopper |33 through conduit |39 and is introduced into conduit |21 or directly into chamber |28 through conduit |42, as shown. The coal and gas mixture from hopper |33 is expanded through either nozzle |4| or nozzle |43, Vor both, with a pressure drop of about 100 to about Y300 pounds per square inch under conditions such that coal' is pulverized to a size less than about 250 microns, preferably less than about 10o microns. This iinely divided coal is suspended in an upward flowing gaseous mixture in chamber |28 un'der conditions such that a pseudo-liquid dense phase of coal indicated by numeral |29 is 'formed therein. Both oxygen and steam may be introduced into chamber |28 by means not shown,
if desired. The temperature of chamber |23 mat7 t.;
be substantially the same or lower than the temperature of combustion chamber |23 and at the temperature existing therein, for example about 1000 F., the `finely divided coal is converted to Ycoke with the resulting volatilization .1
of the volatile components of the coal. The coke formed in chamber |28 and present in the dense phase |29 is Withdrawn ytherefrom by means of standpipe |34. A small amount of the coke vmay be Withdrawn through conduit |35 to prevent the building up of ash in the system. Alternatively or additionally to the Withdrawal of colte through conduit |35 a certain amount of ne ash may be permitted to pass out of chamber' |28 with the gaseous eflluent through conduit |23. The remainder of the coke not Withdrawn through conduit |35 is introduced into conduit |2|, as previously described. A relatively dilute phase is present above the pseudo-liquid dense phase |29. The gaseous eflluent of the dilute phase passes through a cyclone separator |3| in the upper portion of chamber |28 to remove entrained finely divided solids therefrom. These finely divided entrained solids collected in cyclone separator |3| may be returned to the pseudo-liquid dense phase |29 through conduit |32, as shown, ormay be removed from chamber |28 fordisposal, etc. A gaseous effluent from combustion chamber |23 comprising hydrogen, carbon monoxide and volatile components of the coal, such CII "14 as tars, naphthalene, anthracine, benzol, toluol, phenol, cresol, xylol, and normally gaseous and liquid hydrocarbons as well as some nitrogen and sulfur compounds, is removed from the upper portion of chamber |28 through conduit |33 and passed to a conventional product recovery 'system (not shown) for the removal'of the valuable organic compounds from the gaseous effluent.
A modification of the system of Figure 3 will be briefly described With reference to Figure 4, in which modication the distillation of the vo'- latile components from the coal, as in chamber |28, is accomplished in a high velocity system similar to the system for the gasification of the coke in chamber |23. Thus, the reaction eliluent from combustion chamber |23 is passed through conduit |21 to a vol'atilization chamber l5| comprising a cylindrical elongated conduit which may be positioned either horizontally or vertically. VPulverized coal is introduced into conduit |21 through conduit |39, as `previously described'. The lheat of the reaction effluent in conduit |21 volatilizes the volatile components of the coal in chamber |5| and the resulting mixture of hydrogen, carbon monoxide, volatile components of the coal, and coke are passed from chamber |5| through conduit |52 to separator '|53 comprising 'a settling chamber or a cyclone separator. In
separator |53 the' coke is removed therefrom by gravity and passes through a standpipe |511 to conduit |2| for circulation to combustion charnber |23 of Figure 3 inthe manner previously Adescribed. The reaction effluent comprising carbon monoxide, hydrogen, and the previously mentioned volatile components and substantially free yfrom coke is removed from the top of separator |53 through conduit |56. A small proportion of the coke in standpipe |54 may be removed through conduitY |51 in order to prevent the build-up of ash in the system. The primary difference in the modification of Figure 4 from that of Figure 3 is thatthe distillation of the coal to produce coke and recovery of the volatile components is accomplished in a high velocity system, usually with a velocity above about'a feet per second, without the formation of the conventional pseu- `do-liduid dense phaseof solids in the volatilization zone but forming instead a relatively dispersed or dilute phase having a concentration of solids in the range described previously with regard to chamber 38 of Figure 1. In this manner `of operation of the coking chamber, opportunity for the sticking and agglomeraticn of the particles is minimized or substantially prevented.
The embodiment illustrated in Figures sand of the drawing is particularlyl adapted to the recovery of volatile components of the coal and to the production of a high heating value gas. lt
may be desirable, therefore, to introduce a stripping gas into chamber |53 or conduits |34 or 54 by means not shown to aid in the removal of vvolatile components from the coal or coke. Such a stripping gas comprises steam, recycle gas. etc.
In the embodiment shown in Figures 3 and 4 of the drawings, according to one modification, crushed coal may be introduced into conduit |21 through conduit |39 or into chamber |23 through conduit |42 in a size' larger than that used in gasification of the coal in chamber |23. For example, crushed coal havingan vaverage diameter less than about 0.5 inch is introduced through conduits |39 and |42 Without the use of nozzles |4| and |43. In such a casethe pressure of the coal in hopper |3| i sY substantially the same as the pressure existing in conduit |21 and chamber |28. The pseudo-liquid dense phase |29 of chamber |28 will comprise particles of coal of a size greater than the size of the solid particles in chamber |23. Coke is produced in chamber |28 of Figure 3 or chamber |5| of Figure 4 and is passed through conduit or standpipe |34 or |54 to conduit |2|. In conduit |2| the mixture of coke and steam is expanded in a nozzle (not shown) in conduit |2| to achieve the desired neness for the gasication of the coal. The pressure in chamber 28 or chamber |5I and standpipe |34 is less than the pressure existing in conduit |2|, and, therefore, additional means must be supplied, such as lock hoppers, etc., to introduce the coke from conduit |34 or |54 into conduit |2|.
In still another modification of the process of Figures 3 and 4, the reaction eiiiuent from combustion chamber |23 may be cooled such that the reaction is effected in chamber |28 or chamber |5| at a lower temperature than in combustion chamber |23. A cooler or waste heat boiler (not shown) may be inserted in conduit |21 to cool the gaseous eflluent as much as 200 or 300 F., or even more, prior to introduction of the eiiiuent into chamber |28 or chamber |5I. In this manner the operation of the volatilization stage at a lower temperature prevents cracking of the volatile components and increases the recovery of high boiling products.
Figure 5 diagrammatically illustrates another embodiment of this invention for the gasification of coal. In this embodiment a mixture of steam and finely divided coal or coke of the type previously described for use in the gasication process is passed through conduit |1|, burner |12, to gasification or combustion chamber 814. Oxygen and steam are introduced into burner |12 through conduit |13. rlhe gasiiication of the coal is partially effected in chamber |14 under the previously described conditions of operation using a relatively high velocity of gas such that a pseudo-liquid dense phase is not formed in chamber |14 and such that the residence time of the finely divided coal is preferably approximately the same as the residence time of the gaseous mixture passing therethrough. According to this embodiment only partial gasification of the coal is effected in chamber |14 and the unconverted coal is removed therefrom with the gaseous eluent through conduit |16 and passed to separator |11.
.Separator |11 may comprise a single or a series of conventional separators, such assettling chambers, Cottrell precipitators, cyclone separators,
etc., for separating lunconverted coal from the gaseous effluent of hydrogen and carbon monoxide. The gaseous efliuent of hydrogen and carbon monoxide is withdrawn from separator 11 through conduit |18 for storage or use as a fuel or for the synthesis of organic compounds therefrom. Separated coal or carbon-containing material is removed from separatorv |11 through conduit |19 and passed to an enlarged chamber |8|. Enlarged chamber |8| is of ysuch size with respect to the gaseous eilluent passing upward therethrough that the coal is suspended in a pseudo-liquid dense phase, as previously described. A pseudo-liquid phase of solids can be used satisfactorily at this lpoint in the system because the partial conversion in chamber v|14 hasreduced the tendency of the solids to ag- 'glomerate Oxygen andl steam are introduced into chamber EBF through conduit |82 in the appropriate proportions for converting the remaining unconverted or partially converted coal to hydrogen and carbon monoxide. The conditions of operation of chamber |8| are similar to the conditions of operation of chamber |14 and may be varied within limits to achieve the desired result. The gas velocity, of course, will be substantially lower than the gas velocity in chamber |14 and usually lower than about 6 feet per second; for example, about 2 feet per second. A portion of the pseudo-liquid dense phase may be removed from chamber |8| through conduit or standpipe |83 in order to prevent the building up of ash in the system. The reaction eilluent of hydrogen and carbon monoxide is removed from chamber |8| through conduit |84 and passed to conduit |16 where it is combined with the reaction eluent from conduit |14. Alternatively, or additionally, all or a portion of the reaction eilluent from chamber |8| may be passed through a conduit |86 to conduit |1| or directly into chamber 14.
The modification of Figure 5 permits treating the partially converted coal in chamber |8| with a large part of the fresh steam and oxygen, undiluted with product gases. Carbonaoeous residues which are unconverted in chamber |14 because of the short residence time are converted in chamber 8| where a relatively longer residence time is obtained. Unconverted oxygen, and what would otherwise be an excessive amount of unconverted steam, may pass overhead from chamber |8| to chamber |14 through conduit 8b. These unconverted agents are usefully consumed in chamber |14 because they are therein subjected to contact with coal containing its reactive volatile components. In eiectV this separates the process into two stages with provision for countercurrent treatment as between the two stages. Three or more such stages might be used in special instances. By operating in this manner, the temperature in zone |14 may be appreciably reduced so that the production of methane is favored and the temperature in chamber |8| may be several hundred degrees higher than in chamber 14.
Although the figures of the drawings have been described with reference to the explosion pulverization method for obtaining the desired neness of coal for gasification, other methods for obtaining a nely divided coal, such as ball milling, and crushing, may be used without departing from lthe scope of this invention. In such instances where the coal is pulverized by ball milling or otherwise prior to introduction into thesystem, the various nozzles may be omitted and the expansion of the gaseous mixture containing the coal also eliminated. However, it may be desirable to combine the two processes; that is, using a relatively finely divided coal below 250 microns in diameter and at the same time explosion pulverize this finely divided coal to obtain even more nely divided coal. In place of the lock hoppers or standpipes shown in the drawing, a Fuller- Kinyon pump or other screw conveyor device may be used without departing from the scope of this invention. Even certain types of reciprocating pumps may be used to introduce the coal into the system, such as those used on Stoker-nred furnaces. Another method of bringing the coal feed to the operating pressure of the process comprises mixing the coal with water to form a slurry and pumping the slurry to the desired pressure with a conventional slurry pump. The bulk of the slurry water is separated from the pressured coal 17- o by settling, etc., and the thickened slurry is Dreheated to such an extent that the water llashes to steam during the explosion pulverization. Liquid oils may be used in place of water.
In the embodiment of Figures 3 and 4, the coke produced in chmabers |29 and I5i, respectively, may be recovered as a product of the process. In such instances coke is withdrawn through conduits |35 and 157, respectively.
It is usually necessary to aerate the standpipes in the process to maintain the finely divided solids in the standpipes in a uidized condition in order that the solids will iiow. 'Ihe standpipes may be conveniently aerated by introducing into the lower portions thereof a gas, such as steam or recycle gas. 'Y f Therfollowing example is offered as a means of better understanding the application of the present invention to the gasification of coke to produce a gas rich in hydrogen and carbon monoxide. Although in the example specic conditions of operation are specied, these conditions should not be construed to unnecessarily` limit the present invention.
EXAMPLE Approximately 4,00 tons per day of Illinois coke breeze is charged to a combustion zone similar in construction to the type previously described with reference to the present invention. Table I below shows the proximate analysis and the ultimate analysis of the coke.
Table I PROXIMATE ANALYSIS Wt. per geg;
Moisture Ash 24.35 Volatile matter wt. per cent 4.05 Fixed carbon do--.. 70.25
Total combustible 74.30
ULTIMATE ANALYSIS Wt. per gein;
Hydrogen i 1.6
Table II Ste'zsxio g 500 p. s.l i. gage and 12,000Vp0unds/hr. Steam 300 p. s. i. gage and 22,500 pounds/hr.
95% purity oxygen 800 F y5,000,000 s. o. Fg/day. Steam (total) -n 1.03 pound/pound coke. Oxygen (pure) 6.9 S.' C. F./pound coke. The coke breeze is pulverized by means oi explosion pulverization to obtain the necessary particle iineness. The coke feed, initially crushed to 8 or 10 mesh, along with the 500 pound steam which is in the amount of vabout 0.3 pound per pound of solid is expanded from about 500 pounds per square inch to about 295 pounds per square inch gage through a suitable nozzle and the resulting powdered coke and steam is passed into the combustion chamber. The size distribution of the coke is within the approximate range of 65 to 95 per cent through a 200 mesh screen. The 300 pound steam and oxygenare admixed with 'the expanded steam Aand coke. The initia1 cony centration of coke inthe combustion chamber on Y the basis of total feed steam and oxygen is about 0.04 per cubic foot of gas at standard conditions. On the basis of steam and oxygen, at the operate ing pressure and temperature of 1800 F., the concentration is approximately 0.2 pound per cubic foot of gas.'y As the conversion proceeds in the reaction chamber as the gases flow through that chamber the gas volume increases but the solids weight decreases so that the solids concentrations become even lower. The outlet concentration at flowing condition is about 0.045 pound per cubic foot of gas. Since the relatively low solids concentration is maintained in the reaction zone by virtue of the relatively high velocity of the gaseous stream passing therethrough, the linear velocity based upon outlet conditions is about 42.5 feet per second.
It is not necessary to employ such severe pulverization conditions that all of the particles of coke are small enough to be converted in the single pass through the combustion chamber. The coarser particles in the combustion chamber effluent which may contain an average of about 30 weight per cent of unconverted carbon may be recycled to the inlet stream and subjected to further conversion,'to be more fully discussed hereinafter. The combustion chamber comprises an foot length of standard Insidline pipe of 20 inch inside diameter positioned horizontally on suitable concrete supports. The combustion chamber, further, has a thin unstressed liner of Atype 309 alloy (25 per cent chromium; 12 per cent nickel steel) surrounded by a layer of Baldwin- I-Iill type #5 block insulation approximately 3 inches thick.
The combustion chamber effluent comprising hydrogen and carbon rmonoxide discharges into a' vertical fire tube waste heat boiler of conventional design. This Aboiler absorbes 20,000,000 B. t. u.s per hour from the product gas and in so doing cools the gas from about 1800 F. to about l260 F. In this marmer approximately 24,000 pounds per hour of steam is generated at 550 pounds per square inch gage pressure (12,000 pounds per hour more than required by the process). The rst waste heat boiler is followed 'by a second waste heat boiler of similar construction which cools the effluent from the first boiler to a temperature of about 710 F. The second boiler absorbs about 18,500,000 B. t. u.s per hour from the effluent andY generates about 22,500 pounds per hour of steam at 350 pounds per square inch gage pressure. This quantity of steam produced in the second `waste heat boiler is approximately the -amount of 350 pounds steam required for the process. Any deficiency in 350 poundfsteam as a result of the changes in nature of the feed stock can be made up by diverting some of the excess steam from the first boiler.
Thercooled eiiluent from the second Waste heat boiler is introduced into a, cyclone separator. In this separator the larger solid particles containing vunconverted. carbon are, removed fromA the eiliuent. About 45 per cent of the solids entering the cyclone separator 'are removed. These solids are collected and recycled with the feed stream. The heavier solid particles contain on an average about 30 weight per cent of unconverted carbon. The ash in the recycled solids amounts to about 60 per cent of the net quantity of ash in the feed. Unseparated solids in the efliuent from the separator contain only about 5 weight per cent of carbon. l All of the ash entering the process is ultimately eliminated with the separator efliuent.
. 19 The gas analysis of the gaseous eiiluent on a dry 'b asis at this point in the pro-cess is shown in Table Ill beiow constitutes about k30,000,000 standard cubic feet per day of gas..
Table III Vol. percent Nitrogen 1.4 Hydrogen 41.6 Carbon monoxide 41.5 Carbon dioxide 14.8 Methane 0.5 Hydrogen suliide 0.2
The eiiluent gas leaving the cyclone separator at a temperature of approximately 710 F. is heat exchanged in a tubular heat exchanger with the feed water for the two waste heat boilers. The water enters this heat exchanger from a deaerator at a, temperature of about 225 F. and leaves the heat exchanger at a temperature of about 400 F., after absorbing approximately 8.500.000 B. t. u.s per hour or" heat and after cooling the eiiluent gas to about 440 F.
From this last heat exchanger the cooled effluent is passed to a conventional battled scrubbing tower in which the effluent gas is cooled to a final temperature of approximately 100 F. to condense unconverted steam and to remove nely divided entrained ash. The scrubbing tower is maintained at a pressure of approximately 275 pounds per square inch gage. The scrubbing is accomplished by circulating a stream of the water slurry through an outside cooler and over baflies within the tower. A small amount of fresh water is pumped over two conventional bubble-cap trays in the top section of the tower to Wash back slurry entrained from the baffled section.
Carbon dioxide and hydrogen suliide may be removed by water scrubbing in a subsequent tower. The analysis of the gaseous effluent from the carbon dioxide removal tower is shown in Table IV. The quantity of the gas leaving the scrubbing tower is approximately 26,000,000 standard 'cubic feet of puried gas per day with a hydrogen to carbon monoxide mol ratio of about 1:1. The gaseous eiiiuent is suitable for the direct synthesis or hydrocarbons and oxygenated Certain valves, coolers., heaters, pumps, accumula-tors, storage vessels, etc., have been omitted from the drawings as a matter of convenience and their use and location will become obvious to those skilled in the art. The size and length of certain conduits of the drawings may not be proportional to the amount of uid passing therethrough and the distances travelled are merely diagrammatical. It is not intended to limit any particular location of inlets and outlets of the apparatus shown in the draw-ings. The example and theory in connection with the invention are offered as illustrations and should not be construed to unnecessarily limit the invention.
Having described my invention, claim:
1. A process for the gasification of carbon-containing material to produce a gas rich in hydroeen and carbon monoxide and substantially free from methane which comprises suspending in a reaction zone a casing type coal in finely divided form containing initially no more than a minor proportion by weight of material whose average particle diameter is greater than about 2.50 microns in a fiowing gaseous mixture comprising oxygen and steam under conditions such that hydrogen and carbon monoxide are produced as products ofA the process, supplying the required heat of conversion to said reaction zone by direct heat exchange, maintaining the linear gas velocity suiiiciently high such that the heaviest particles of finely divided solid continuously move inthe direction of flow oi the gases, maintaining the temperature of reaction above 1800" F. and belowl 2600o F. and a lpressure between about 250 and about 1000 pounds per square inch gage and a residence time of solid material in said reaction zone less than about 5 seconds, and removing a gaseous eiiuent containing hydrogen and carbon monoxide from said reaction zone substantially tree from methane as a product of the process.
2. The process of claim l in which both steam and oxygen are introduced tangentially into one end of the reaction zone.
3. A process for the gasication of a caking type coal to produce a gas rich in hydrogen and carbon monoxide which comprises passing a gaseous mixture of oxygen, steam and 'finely divided caking type coal which coal has a particle size less than about 250 microns upward through a reaction zone at 'a linear gas velocity between about 8 and about 100 feet per second such that theheaviest particles of finely divided coal con- Vtinuously move in the direction of flow of the gases and slippage ofthe iinely'divided coal is substantially negligible, maintaining a feed ratio to said reaction zone Aoi oxygen between about ltand about 15 cubic feet per pound of coal .and of steam between about `0.2 and abouti pounds per pound of coal, maintaining said reaction Vzone at a temperature between about 1800 F'. and about 2600 F. and under a pressure between about 250 and about 1000 pounds persquare inch gage, maintaining the temperature of the inside of the reaction zone at a higher temperature than the temperature on the outside of the reaction zone, maintaining the concentration of coal in said gaseous mixture flowing through said reaction zone between about 0.01 and about 0.5 pound of coal per cubic foot of gas-.at standard conditions of temperature and pressure, maintaining a residen-ce time of powdered suspended coal in said reaction zone less than about 5 seconds, whereby a gaseous eiuentV is produced rich in carbon monoxide and hydrogen and substantially free from methane, and withdrawing from .reaction zone at a linear gas velocity between about 8 and about 100 feet per second such that l the heaviest particles of finely divided coal continuously move in the direction of ow of the gases, maintaining said reaction zone at a tem- 2l perature between about 1800 F.an'd'about 2600" F. land under a pressure between about 250 and about 1000 pounds per square inch gage, maintaining the temperature of the inside ofthe reaction zone Yat a higher temperature than the temperature on the 'outside of the reaction zone, maintaining aresidence time of powdered suspended coal in'said reaction zone not substantially greater than about 10 seconds, whereby a gaseous effluent is produced rich in carbon monoxide .and hydrogen and substantially free from methane, and withdrawing from said reaction zone such an eliluentV as a product of the process. 5. A process for the gasication of a oaking type coal which comprises suspending in a reaction -zone a powdered caking type coal in a owing gaseous mixture comprising oxygen and steam under conditions such that hydrogen is produced as a product of the process, supplying the required heat of conversion to said. reaction zone by direct heat exchange, maintaining a linear gas velocity sufliciently high such that the heaviest particles of powdered coal continuously move in the directionrof now of the gases, maintaining the temperature of reaction above 1800o F. and below 2,600o F'. and a pressure between about 250 and about 1000 pounds per square inch gage and a residence time of powdered coal in said reaction zone less than about 5 seconds, removing a gaseous effluent containing hydrogen and substantially free from methane and containing powdered unconverted coal from said reaction zone, separating powdered unconverted coal from said gaseous eluent and recycling the separated unconverted coal to said reaction zone.
6. A process for the gasification of a caking type coal which comprises expanding a mixture of steam and caking type coal under conditions such that coal is reduced to a size less than about 250 microns, passing the resulting mixture of steam and nely divided coal to a reaction zone, introducing oxygen and steam into said reaction zone adjacent the point of introduction of said mixture of steam and finely divided coal, maintaining a linear gas velocity within said reaction zone suiiiciently high such that the heaviest particles of finely divided coal continuously move in the direction of flow of the gases, converting coal, steam and oxygen to hydrogen and carbon monoxide in said reaction zone, maintaining the temperature of reaction above about 1800L7 F. and below about 2500 F. and the pressure between about 250 and about 1000 pounds converted coal from said reaction zone, separating unconverted coal from said eiiuent, and recycling the-separated unconverted coal to the original gaseousmixture ofsteam and coal.
7. A process for the gasication of a caking type coal to produce a gas rich in hydrogen and carbon monoxide which comprises passing a gaseous mixture of oxygen, steam and powdered caking type coal throughra reaction Zone at a sufficiently high linear gas velocity such thatV the heaviest particles of coal are continuously moved in the direction of flow of the gases under conditions such that coal and steam are con- 22 verted to hydrogen and carbon monoxide, main'- taining the temperature of the inside of the reacltion zone at a higher temperature than the temperature on the outside of the reaction zone, maintaining a temperature of conversion between about 1800 F. and about 2600 F. and a lpressure between about 250 and about 1000 pounds per square inch gage, maintaining the concentration of coal in said gaseous mixture flowing through Asaidreaction Zone less than about 1 pound of coal per cubic foot of gas, maintaining a residence time of coal in said reaction vzone not substantially greater than about 10 seconds, whereby a gaseous eiiiuent is produced rich in hydrogen and carbon monoxide and substantially free from methane, and withdrawing such a gaseous effluent from said reaction zone as a product of the process.
i8. A process for the gasication of a caking type coal to produce a gas rich in hydrogen and carbon monoxide which comprises passing a gaseous mixture of oxygen, steam and powdered caking type coal through a reaction zone at a suiiiciently high linear gas velocity such that the heaviest particles of coal are continuously moved in the direction of low of the gases under conditions such that substantially all of the coal is converted in a single pass through said reaction Zone, supplying substantially all of the required heat oi conversion to said reaction zone by direct heat exchange, maintaining a temperature of conversion above about 1800o F. and below about 2600" F. and a pressure between about 250 and about 1000 pounds per square inch gage, and maintaining a residence time of coal in said reaction zone .not Substantially greater than about l0 seconds, whereby a gaseous effluent rich in hydrogen and carbon monoxide and substantially free from methane is produced, and removing such an ellluent from said reaction zone as a product of the process.
9. A process for the gasification of a caking type coal which comprises passing a stream of steam to a mixing zone in which oxygen is introduced into said mixing zone angularly and circumferentially at a plurality of points to the stream of steam, introducing powdered 'caking type coal into said stream of steam passing to said mixing zone whereby powdered coal is carried therewith to the mixing zone and is admixed with the oxygen therein, passing the gaseous stream containing powdered coal and steam through an elongated reaction zone from said mixing zone, supplying sufficient oxygen to said mixing zone to burn nely divided coal in an amount to supply the required heat for the con version of coal and steam to hydrogen and carbon monoxide, passing the gaseous stream of powdered coal and steam through said reaction zone at a suicientlyhigh linear velocity such that the heaviest particles of powdered coal are continuously moved in the direction of now of the gases therein, maintaining a temperature of reaction above about1800 F. and below about' 2600u F. in said elongated reaction zone and a pressure Vbetween about 250 and about 1000 pounds per square inch gage, maintaining a residence time of powdered suspended coal in Asaid reaction zone not substantially greater than about 10 seconds, whereby a gaseous eiiiuent rich in hydrogen and carbon monoxide and substantially free from ethane is produced, removing from said reaction zone such an effluent containing ash formed in said reaction zone, separating ash from said gaseous elluent. and re- Lcovering the gaseous eiiiuent as a 'produotjoi A,the
10. The process of claim 9 in which oxygengis introduced into said mixing zone tangentially to said stream of steam `and powdered coal such that a whirling motion is imparted vto the mixture leaving the mixing zonev andv passing into said. reaction zone.
11. A process for the gasification oi a caking type coal which comprises passing a .gaseous mixture of steam and powdered caking type coal through an elongated reaction zone suieient to permit a residence time not substantially greater than about 1() seconds for substantial conversion of coal and steam to hydrogen and carbon monoxide, maintaining a linear gas yVelocity in said reaction zone such that powdered coal continuously moves in the direction of flow of the gases in a highly dispersed condition whereby the tendency of the caking type coal to stick together is minimized at the temperature of con Version, maintaining a temperature of oonversion between about 1200o F. and. about 2600o F. and a pressure between about 250 and about 1000 pounds per square inch gage, maintaining the temperature of the inside o the reaction zone at a higher temperature than the temperature on the outside of the reaction zone, sup-plying sufficient oxygen to said reaction zone to raise the temperature of the reaction zone to the desired level for the conversion reaction, whereby a gaseous efiluent comprising hydrogen and carbon monoxide and substantially free 1frommethane is produced, removing from .said reaction Zone such an .effluent and containing .nely divided entrained ash, separating ash from said eluent, and recovering the eiiuent as a product of the prozess.
NORMAN L. DICKINSON.
References Cited in the file 0f this patent STATES Number Name Date 1,899,887 Thiele Feb. 28, '1933 '1,983,943 Odell Dec. 11, 1934 2,111,579 Winkler et al. Mar. 22, 1938 2,385,508 Hammond 1 Sept. 25, 1945 2,414,586 vEglofl Jan. 21, 19.47
' 2,482,187 ,Johnson ...7 Sept. 20, 1949 FOREIGN PATENTS Number Country vDate 9,498 Australia Jan. 25, 1928 of 1927 y 286,404 Great Britain Mar. 8, 1928 528,338 Great Britain Oct. 28, v1940 532,342 Great Britain Jan. 22, 1941 585,354 Great Britain Feb. 5, 1947 OTHER REFERENCES Chemical and Metallurgical Engineering, vol. 24 (1921), pages 600 to 604.
Chemical Engineering, Jan. 1947, pages to 108.
Chemical Engineering Process, vol. 43 (Aug. 1947), pages 429 to 436.