US2886421A

US2886421A - Treatment of carbon-containing materials

Info

Publication number: US2886421A
Application number: US382906A
Authority: US
Inventors: Norman L Dickinson
Original assignee: MW Kellogg Co
Current assignee: MW Kellogg Co
Priority date: 1947-06-02
Filing date: 1953-09-29
Publication date: 1959-05-12
Anticipated expiration: 1976-05-12

Description

May 12, 1959 N. l.. DlcKlNsoN TREATMENT 0F cARBoN-coNTAINING MATERIALS 3 sheets-sheet 1 i Original Filed June 2. 194'? i ATTHZEYE l N. L. DlcKlNsN TREATMENT oF CARBON-CONTAINTNG MATERIALS May 12., 1959y 3 Sheets-Sheet 2 Original Filed June 2. 1947 |...IT'I

INVENToR. NOR/'MN L, DIEM/V56 TTHNEYS May l2, 1959 N. LznlcKlNsoN E 2,885,421

TREATMENT oF 'CARBON-CONTAINTNG MATERIALS original Filed June 2.1947 :s sheets-sheet s D E S Q \1 A T VJ- N 73 EE N 53 k In? IQQ t l NN Q N E g ll. w y

5 ,E il

l\ E m QD q f Q Si N v Q K E N "Q E. 1 Q Q INVENTOR. LL s" /l/oRMA/v D/cknvsa/y ATTRZVEW United States PltCIlf P 'TREATMENT 0F CARBUN-CONTAININ G MATERIALS Norman L. Dickinson, Basking Ridge, '.N..l., assignor to The M. W. Kellogg Company, Jersey City, NJ., a corporation of Delaware 9 Claims. (Cl. 48-206) v This invention relates to the treatment of carbon-containing material. In one aspect this invention relates to the high temperature treatment of solid carbon-containing materials, such as coal and coke. More specifically, in one aspectpthis invention relates to the production of a gas richV in hydrogen from coal or other solid carboncontaining materials. This application is a division of my prior and copending application Serial No. 751,728, iiled June 2, 1947, now Patent No. 2,662,007, issued December 8, 1953.

It has been known for some time that coal may be treated with oxygen and steam at relatively high temperatures to convert the coal to hydrogen and carbon monoxide, which products are useful for the synthesis of organic compounds. In general, coal, coke, or other carbon-bearing solid materials are contacted with oxygen and steam in an amount of about 10 cubic feet of oxygen per pound of steam per pound of coal at a temperature above about 1000 F. under conditions such that the carbon, steam, and oxygen are converted to hydrogen and carbon monoxide.

Various methods have been practiced to eifect the gasilication of coal to produce a gaseous effluent rich in hydrogen and carbon monoxide. Among these methods is that known as the Lurgi process, which comprises countercurrently contacting a moving bed of crushed or lump coal with an upward ilowing mixture of oxygen and steam. A temperature between about 600 F. and about 1600 F. or higher is maintainedv between the top and bottom, respectively, of the moving bed of coal and a pressure of about 200 or 300 pounds per square inch gage is maintained during the gasiication process. This process is characteristic of producing a gaseous effluent containing hydrogen, carbon monoxide, and considerable quantities of carbon dioxide and methane.

Also, among these known methods for the gasication of coal is the Winkler process which comprises passing oxygen and steam through a so-called iluid bed of finely divided coal at a 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 in diameter such that the pulverized coal is suspended in the gaseous mixture under the conditions of operation. In theWinkler operation a relatively low upward gas velocity characteristic of that necessary to produce a pseudo-liquid iluidized condition is employed. The gasification of the coal by the Winkler process produces an effluent rich in hydrogen and carbon monoxide and substantially free from methane.

The Huid-bed type operation of the Winkler 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 fluid-bed process produces hydrogen and carbon monoxide with only minor amounts of methane, which fact is desirable when the 2,886,421 Patented ,May 12, 1959 HCC product gas is to be used for the synthesis of hydrocarbons. Even in view of the relatively good results obtained by the fluid-bed type operation, certain inherent disadvantages have been found. In such iluid-bed operations in which the nelydivided coal is suspended in a gaseous mixture of oxygen and steam, classification of the coal often occurs. There is also .a tendency for the fluid-bed to settle as a result of fusion and sticking or caking of the iinely divided particles at the temperatures required for the gasication reaction.

These difficulties have required certain design considerations and have limited the maximum temperature in the luid-bed operation in order to prevent settling and agglomeration of the nely divided suspended coal and maintain the finely divided coal continuously in a fluidized condition. The sticking or caking of the coal particles limits the use of the Winkler process to special grades of coals which do not have this tendency to stick at high temperatures. lIt is desirable, therefore, to provide a process and apparatus which overcome these difculties.

An object of this invention is to provide a process and apparatus for the gasification of carbon-containing solid materials. y

Another object of this invention is to provide a process for the production of hydrogen from carbon-containing solid materials.

Further, another object of this invention is to provide a process for the production of coke from coal.

It is a further object of this invention to produce 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. provide a method for the recovery of volatile components of coal.

Yet a further object of this invention is to provide a process for the gasication of low-grade carbon-containing solid materials which are ordinarily unsuitable for other types of gasification processes.

1t is an object to provide a coal gasification process which permits accurate control of hydrogen and carbon monoxide concentrations in the effluent gas within wide limits. n l

A further object is to provide an economical process for gasifying fines of coal and coke, such as coke breeze, lwhich could not be processed in present processes by virtue of their small particle size.

Various other objects and advantages will become apparent to those skilled in the art from the accompanying description and disclosure.

It Ihas been found that carbon-containing material can be converted to a gaseous effluent rich in hydrogen and carbon monoxide by suspending or entraining linely divided slolid material containing carbon in a stream of oxygen and wsteam at relatively high temperatures and high pressures.. According to this invention, finely divided coa1 is introduced into a rapidly flowing gaseous stream of oxygen and steam under conditions such that the heaviest particles are continuously moved by entrainment in the direction of flow of the gaseous stream. The linear velocity of the gaseous stream carrying the coal must be above about 8 feet per second and may be as high as feet per second, preferably at a velocity of about l5 to about 60 feet per second, whereby the nely divided particles of coal are entrained in the gaseous mixture in an amount lessnthan about 1 pound per cubic foot of gas (at standard conditions) generally between about 0.01 and about 0.5 pound per cubic foot of gas. Under such conditions of velocity, the conventional pseudo-liquid or fluidized dense phase of nely divided particles is not formed but instead a dilute phase of finely divided and highly dispersed particles is produced which permits much higher temperatures of reaction than heretofore possible with conventional fluid-bed type operations using comparable quality coals. Pressures from about 100 to about 1000 pounds per square inch gage and temperatures from above about 1400 F. to about 2600 F. are employed. At the high gas velocities and degree of dispersion of the coal of this invention, substantially complete conversion of the carbon to hydrogen and carbon monoxide can be effected at high temperatures without agglomeration. Operations according to this invention also enable a large capacity per unit volume of size of equipment. Methane can be produced together with hydrogen and carbon monoxide according to one embodiment of the present process by using temperatures lower than 1800 F. and as low as about 1000D F. Thus, when it is desirable to produce methane along with hydrogen and carbon monoxide, such as for fuel purposes, this may be done conveniently by regulating the temperature along with such other conditions as residence time of the coal and the ratio of steam and oxygen.

Generally, the ratio of oxygen to coal and steam to coal may be varied from about 4 to about 15 cubic feet of oxygen per pound of coal and from about 0.2 to about 5 pounds of steam per pound of coal, respectively. The proportion of oxygen, steam, and coal is regulated within the above ranges to control the temperature of conversion and also to control the conversion of coal per pass for a given residence time of coal. As the interaction between steam and carbon is endothermic and that between oxygen and carbon is exotherrnic, surcient oxygen must be introduced into the conversion zone to maintain the desired temperature of reaction.

Complete conversion or gasification of the coal to gaseous products when operating according to this process is achieved by a residence time of the carbon-containing material in the reaction or gasiiication zone of about ten seconds or less per pass. The reaction zone should be of such length with regard to the gas velocity that sufficient residence time is provided for substantially complete gasiiication. However, the reaction zone may be of such length to provide insuflicient residence time for complete gasication of the coal in one pass, and in such case unconverted coal is recycled to the reaction zone to complete the gasication thereof.

Various solid carbon-bearing materials may be ernployed and can be converted to hydrogen and carbon monoxide according to the teachings of this invention. Such carbon bearing materials comprise various types of coal, such as anthracite, 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 aiorded for agglomeration of the coal particles at such high velocities and at such low concentrations encountered in the process of this invention. Furthermore, since the tendency of the'carbon-containing materials to agglomerate or fuse in the reaction zone is practically eliminated, relatively higher temperatures can be used, if desired, than in other conventional coal gasication processes. For example, at pressures above about 250 pounds per squareV inch gage and at temperatures above about 1800 F., a gaseous efuent containing hydrogen and carbon monoxide substantially free from methane is obtained. Such a gaseous effluent is highly desirable for subsequent use for the conversion thereof to organic compounds by various known synthesis processes.

For the gasication of coal or other solid carbon-containing materials according to the present invention, the coal must be in a nely divided powdered form. Preferably, the powdered solid material initially contains no more than a minor proportion by weight of material whose average particle diameter is greater than about 25 0 microns. An example Iof a desirable powdered coal is one in which about 75 to 95 percent by weight passes through a 200mesh screen. The pulverization of the coal may be eleted by various GQuventional means, such as by grinding in a ball mill, as by conventional equipment known as the micronizer, or by explosion pulverization, without departing from they scope of this invention.

Generally, the reaction zone itself will comprise a single conduit or tube of an inside diameter between about 1 and about 6 feet. Preferably, the reaction tube is of sufficient length with respect to the velocity of the gases therein that substantially complete gasification of the carbon-containing material is elected in a single pass and may contain bellies and/ or orifice plates to obtain the desired turbulence, especially in the larger diameter reaction chambers.

This process is distinguishable over those processes which employ a Huid-bed type operation. In the uid-bed type operation, the finely divided solid material forms a so-called pseudo-liquid dense phase of suspended material in the reaction zone and consequently the carbonaceous material remains in the reaction zone itself in this dense Huid-bed until gasied or converted. The concentration of solid material in the dense fluid bed is much greater than the concentrations of solid material in the reaction zone of this invention. In the dense phase process the concentration is usually greater than about 10 or 20 pounds of solid material per cubic foot of gas and may be as high as pounds per cubic foot of gas at standard conditions. Usually, in the conventional pseudoliquid dense phase process, the reaction zone is of such a volume and cross-sectional area and the gas velocity is sufciently low that the iinely divided material is suspended in a fluid bed with the presence of a so-called interface of rapidly decreasing concentration between the fluid bed and an upper dilute phase. The upper dilute phase contains a small amount of ash and 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 a 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 this 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 carboncontaining 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 ow the velocity should be sulficiently high to cause turbulent flow thereby preventing settling of the nely divided coal.

In vertical flow, 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, the velocity of the gas is such that slippage of the finely 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 per unit volume of size of equipment.

The gasication of coal is effected according to the following typical equations:

As high as 99.5 percent overall-conversion and as high as 85 percent carbon monoxide' yield based on carbon feed is achieved when operating a process within the preferred conditions of ythis invention. The effluent from the conversion zone contains on a dry basis about 30 to about 50 volume percent carbon monoxide, about 35 to about 55 volume percent hydrogen, about 10 to about 20 volume percent carbon dioxide, and about 0.1 to about 25 volume percent methane.

This invention will be discussed further by reference to the accompanying drawings which comprise views in elevation, partly in cross-section, of suitable arrangements of apparatus for carrying out theprocess of the present invention. Figure 1 of the drawing is an elevational view, partly in cross-section, diagrammatically illustrating an arrangement of apparatus for the productionof a gas ric'h in hydrogen and carbon monoxide yfrom finely powdered coal. Figure 2 is =a diagrammatical illustration, partly in cross-section, of a modification of combustion charnber 38 yof Figure 1. Figure 3 is another embodiment of the present invention as applied tothe recovery of volatile material from coal and subsequent conversion of, coke to carbon monoxide and hydrogen, anddiagrammatically illustrates an elevational view of apparatus, partly in cross-section, for such an embodiment. Figure 4 is a diagrammatic illustration in elevation of a modiiication of chamber 128`of Figure 3. Figure 5 is still another embodiment of the present invention diagrammatically illustrating an elevationalview of a suitable arrangement of apparatus for the production of hydrogen and carbon monoxide from coal. y

In Figure 1 of the drawings crushed coal is introduced through conduit 11 into'storage Vessel 12. The coal, preferably, isA of a size such that it will pass an 8 to 16 mesh'screen. The crushed coal iiows from storage" vessel 12 through a branched conduit 13 into a series of par-l

allel lock hoppers

14, 16, 17, and 18, as shown. By means of these lock hoppers the coal is raised to a desired pressure for operation of the process. In lock hoppers 14 and 17 the coal therein is pressured with a gas introduced through conduits-22 and 23. In these first lock hoppers the coal is pressured, for example, to `a pressure of about 200 to about 300 pounds per square inch gage. The coal is then passed at this pressure into the next hoppers, 16 and 18, in which the pressure of the coal is raised by means of a gas to about 500 to about 600 pounds per square inch gage, orhigher. The pressuring gas is introduced into lock hoppers 16 and 18 lthrough either conduit 19 or conduit 21. The hoppers are worked alternately in series; that is, one series is` introducing the pressured coal into conduit 32 under conditions ofvcontrolled flow while'the otherv series is being pressured. After the coal has been introduced into conduit 32 from either of hoppersy 16 or 18, for example,'hopper 18, the gases under the pressure existing in hopper 18 are expanded into hopper 17 in which coal has been introduced. The coal is then passed from hopper 17 to hopper 18 at the pressure existing in hopper 17. Pressuring gas lis introduced into hopper 18 through conduit 21 or conduit 19 to raise the pressure'to the desired value.

Steam, for example,k at a pressure from about 500 to about 600 pounds per squareinch gage and only a few pounds above the pressure of the'coal in hopper 18, is' continuously passed from a conventional highpressure steam lboiler 29 through conduit 31 to conduit 32. `The steam passes through conduit 32 into which crushed coal is continuously injected from hoppers 16 and 18. The resulting mixture is conveyed through conduit'32 to a conventional expansion nozzle 34. v

In nozzle 34 the steam containing the entrain'ed coal is expanded into conduit 36 to a pressure` lower than that pressure existing in conduit 32, usually about 70 to about 300 pounds per square inch lower vthan in conduit 32'. By virtue of the suddenexpansion of the mixture of gases and coal in nozzle 34, the gases or liquid n the pores of the coal are also rapidly expanded causing pulverization of the coal. Some pulverization may be effected by the impact between particles in the turbulent wake of nozzle 34. This explosion puverization 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, suiicient size reduction of the coal can be achieved with pressure drops as small as 75 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 size of 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 desired particle size.

Natural gas, recycle gas from a synthesis process for producing `hydrocarbons landv organic compounds from hydrogen and carbon monoxide, or recycle gas from the coal gasification'processlitself may be introduced into the 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 31 and may be introduced and admixed in conduit 32 or may be passed through conduit 33 and admixed with the steam and pulverized coal in conduit 36. The 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 37 and a vertically positioned combustion chamber 38. Burner 37 comprises a cylindricalv chamber in which the gaseous mixture of coal and steam is introduced atone end thereof and steam and 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 37 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 combustion chamber 38, such as through burner 37. Oxygen may be produced in any conventional manner in oxygen plant 40, such as by refrigeration and condensation of air to separate the oxygen therefrom.k Substantially pure oxygen, usually between about and about 98 percent purity, is passed from oxygen plant 40 by means of compressor 41 through conduit 42 to a conventional preheater 43. In preheater 43, the oxygen stream is heated to a temperature between about 500 F. and 1000 F. Oxygen is passed from preheater 43 through

conduits

44, 51, 52, and `53 to burner 37.

When insuflicient steam is supplied from high pressure steam boiler 29 for eiecting the reaction or gasiication of the coal in chamber 38, or for other reason, additionalV steam may be introduced into the system through conduit 46. Such additional steam is generally at a lower pressure than steam from boiler 29 and is passed through a conventional super-heater 47 in which the steam is heated tov a temperature between about 750 F. and 1700" F. Super-heated steam is passed from superheater 47 through conduits 48 4and 49 to conduit 36 for admixturewith the steam and coal mixture therein. Alternatively or additionally, the steam from conduit 48 may be introduced and admixed with the oxygen in conduit 51, asy shown, andkthen passed through

conduits

52 and 53 to burnery 37. vPreheating of the reactants reduces the quantity of oxygen required to obtain'the desired conversion temperature.

The amount of oxygen supplied through

conduits

52 and 53 is between about 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 adlmixture with the oxygen through conduits52 and 53 is initially between about A 0.2 and about 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 37 the coal is ignited and passes as a llame together with the oxygen and steam from burner 37 into combustion 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. Combustion chamber 38 is of such cross-sectional area that the velocity of the gas is above about 8 feet per second, and, preferably between about and about 60 feet per second, and may be as high as 100 feet per second. The temperature 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 the operating pressure. Under these conditions of operation and at the high pressures involved the finely divided coal particles are carried along with the upward owing gaseous mixture without the formation of the conventional pseudo-liquid dense phase characteristic of lower velocities. At velocities between about 15 and about 50 feet per second the particles of coal are carried along by the gaseous stream substantially at the same velocity as the linear velocity of the gas. However, some slippage of the solid particles may be evidenced in the vertical chamber 38, but this slippage is usually not much more than about 50 percent in the extreme cases. Under these conditions of operation the concentration of coal in the gaseous reaction mixture is very low, usually between about 0.01 and about 0.5 pound of coal per cubic foot of gas at standard conditions of temperature and pressure. The residence time of the coal in the combustion chamber is substantially the same as the residence time of the gas ilowing 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 gasication thereof; such times usually being less than about 5 seconds and often as low as l or 2 seconds.

As previously discussed, if it is desired to produce a substantial quantity of methane in the ultimate gaseous eluent from combustion chamber 38, lower temperatures are necessary; usually, thetemperature is below about 1800 F. and preferably about 150,0" F. depending upon the operating pressure. The ltemperature of reaction is lowered by altering the ratios of oxygen and 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 39 to a waste heat boiler 54 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 andl 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 eluent is cooled to a temperature of about 1000 F. or lower. The cooled yeflluent is then passed from boiler 54 through conduit 56 to a separator 57. In separator 57, ash and any unconverted or partially converted carbon-bearing material are removed from the gaseous eflluent. Separator 57 may comprise a single or plurality of cyclone separators, a Cottrell precipitator, lters, or other conventional means for separating nely divided solids from a gaseous mixture. A small amount of ash may be allowed to pass out of separator 57 with the gases. Ash and carbonbearing material separated in cyclone separator 57 are removed therefrom through conduit 58 and passed to a hopper or storage vessel S9. From storage vessel 59 the ash and unconverted or partially converted coal kare recycled or returned to lock hoppers 16and 18 through

conduits

61 and 19 by means of steam introduced through conduit 19. In order to prevent the build-up of the-ash content inthe system, a portion of the recycled ash and unconverted or partially converted coal may be withdrawn through conduit 62 for disposal, or means may be provided for separating ine ash from unconverted coal, such as by allowing ash to pass overhead in lseparator 57. If desired, unconverted ash and ,coal may be recycled directly to conduit 36 and ultimately to combustion chamber 38 through

conduits

19, 62, and 63. The-ash separated from the euent in cyclone separator 57 may be disposed of directly, if desired, and this may often be the preferred manner of operation where substantially all of the carbon-bearing material is converted to gaseous products. In such a case hopper 59 and its connecting conduits may be omitted.

A gaseous elluent substantially free from unconverted or partially converted carbon-bearing material is passed from cyclone separator 57 at a temperature of about 1000 F. or lower through conduits 68 of a conventional water heater 67. Water is passed to water heater 67 through conduit 66 and is heated under pressure to a temperature of about 400 F. If a pump is installed between heater 67 and subsequent boilers, then the pressure on the water side of heater 67 need be only that necessaryto suppress vaporization therein. kThe heated water is passed from water heater 67 through conduit 69 to a steam drum or storage tank 72. If additional water is vdesired above that needed to cool the effluent from separator 57, such water may be introduced into conduit 69 through conduit 71. The heated water is then passed under pressure from steam drum 72 through conduit 76 for indirect heat exchange with the combustion chamber efuent in boiler 54. In boiler 54 water is vaporized under pressure to produce steam which is removed therefrom together with unvaporized water through conduit 77 and returnedto steam drumy 72 by thermosiphon circulation. In this manner of heat exchange between the effluent of the combustion chamber 78 and water, generally substantially all of the steam required in the process is produced with the resulting economical advantage of conservation of heat. This steam thus produced is passed through conduits 78 and 79 to conduit 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 42 with the efuents in

conduits

39 or 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 at a temperature of about 300 F. to 600 F. is passed through conduit 81 to scrubbing tower 82. The entire system, including scrubber tower 82, is at approximately the pressure existing in conduit 36 after the expansion of the.coal and gaseous mixture through nozzle 34. In scrubber 82 the gaseous eilluent passes upward through bafes 84 countercurrently to a downward flowing stream of water introduced through conduits 83 and 87. The liquid scrubbing medium removes ne ash entrained in the effluent, which has not been removed by cyclone separator 57, and also further cools the gaseous etlluent to a temperature of about F. or lower and condenses any water vapor in the efuent. The scrubbing medium collects in the lower portion of scrubber 82 as indicated by the liquid phase 85. A major proportion of this liquid phase is recycled through conduit 87 and cooler 88 to the upper portion of scrubberV 82.` The heat 1 at a temperature of about 100 F. or lower is removed from scrubber 82 through conduit 91 and may be passed to storage (not shown) or may be used directly as a fuel, as a feed gas for the synthesis of hydrocarbons and oxygenated organic compounds therefrom, or in the pro# duction of hydrogen. The coal gasification efiiuent contains, besides hydrogen and carbon monoxide, relatively small amounts of carbon dioxide, methane, and sulfur compounds, such as hydrogen sulfide. The sulfur compounds are produced from small amounts of sulfur in the coal. These compounds -present as impurities may be removed from the effluent by conventional means (not shown). f

y 10 changer, prior to'y introduction into scrubber 82. When expanding the effluent' through a turbine, it is desirable to remove substantially all of the solid particles larger than 10 microns in diameter from the eiiiuent in order to prevent erosion ofthe turbine blades,

Although combustion chamber 38 has beenshown Iand described as positioned vertically, it may be positioned horizontally or' angularly without departing from the scope of this invention. l i

ySubstantially pure oxygen is much preferred for reacting with the coal; however, in some instances air may be employed directly as the source of oxygen by injecting airA into combustion chamber 38 through

conduits

52 and 53. f v

Figure 2, partly in cross section, is an elevational view diagrammatically illustrating a modification of combustion chamber 38 of Figure l.. In Figure 2 the gaseous v mixture of coal and steam, and in some cases natural gas f' A portion of the gaseous efliuent comprising hydrogen and carbon monoxide may bev returned tothe lock hoppers as a pressuring gas or may be used as a conveying or vexpansion medium as previously indicated. Recycling in the labove :manner is accomplished by passing a portion of the gaseous eiiuent from conduit 91 through conduit 92 to knockout drum 93 in which entrained Vwater is separated from the gaseous eiiluent and removed from drum 93 through conduit 94. The gaseous mixture substantially free from entrained liquid is removed. from drum 93 and passed through conduit 95 to compressor 96. In compressor 96 the gaseous eiiiuent is compressed to the desired pressure for repressuring the lock hopper's. The compressed eiuent is then passed to a second drum or accumulator 97 in which any condensate formed by the compression is removed fromthe gaseous mixture through conduit 98. A cooler (not shown) `may beinserted between compressor 96 andraccumulator 97 to condense water vapor from the gases, 'if desired.v The gaseous recycle mixture is passed from accumulator 97 through conduit 99 to conduit 22 for

repressuring lock hoppers

14, 16, 17, and 18 as ,previously described, or through conduits 99 and 101 to hopper 59 for pressuring that hopper. If desired, a portion or all of the recycled eiiiuentfrom conduit 99 may be passed through conduit 100 to conduit 19 and used for returning ash from hopper 59 to the

lock hoppers

14, 16, 1,7, and 1,8.

Cooling of the effluent in conduit 81 and further removal of solids therefrom may be unnecessary; therefore, the omission of scrubber 82 is contemplated in certain instances. y f

Excess water from heater orcooler 67 that cannot be converted to steam in boiler 54 is removed from conduit 69 through conduit 73. A portion or all of the water in conduit 73, as needed, is passed to high pressure steam boiler 29 through conduit 74 by means of apump (not shown) as a source of thehigh pressure steam for con-v veying the coal in conduit 32. Water for producing steam in boiler Z9 may-be obtained from an outside source, if necessary. The gaseous eiiiuent from separator 57 may be expanded through a conventional expansion turbine (not shown) in order to utilize a portion of the heat and pressure of the gases. The power produced in the turbine by the expansion of the effluent gases may be used to compress gases of the process, such as the oxygen reactant, or the air to the oxygen plant 40, or to generate electricity. Although theV expansion of the gases in the turbine cools them, it may still be necessary to cool them further, as when the inlet temperature to the turbine is as high as l500 F., such as by passing the gases from the turbine through a conventional cooler or heat exor recyclegases, is passed from conduit 36 into burner 37, as previously described with reference to Figure l. Oxygen Iand steam may be introduced into burner 37 through conduits S2 and 53. Steam-is introduced when necessary into conduit 36 through conduit 49. The mixtureof steam, oxygen, and entrained iinely divided coal passes through combustion chamber 38, as previously described with reference to Figure 1, at a characteristically high Velocity and at a relatively low concentration of solids percubic foot ofgas under conditions such that at least about l0 percent of .-the-carbonaceous matter is converted to hydrogen and carbon monoxide. A mixture of solids and gases pass upward through combustion chamber 38 into the lower portion of enlarged vertical chamber 111. In enlarged chamber 111 the entrained solid particles form a so-called pseudo-liquid dense phase as the result of the decrease in Velocity ofthe upward flowing gases. The gas velocity in chamber 111 is such that the finely dividedparticles are not entrained or carried'with the gas but instead remain in chamber 111 in a fluidized condition. Thus the pseudo-liquid dense phase indicated yby numeral 112 isa stationery bed of highly turbulent finely divided material. Grid or screen 113 is provided to uniformly 'distribute the upward flowing gases and to aid in maintaining a lower extremity of the pseudo-liquid dense phase 112 whereby the formation of the dense phase below grid113is prevented. Additional steam or oxygen may'be introduced into chamber 111 through conduit 116` below ygrid'113.

In chamber 3841partial gasication or conversion of the coal is effected in accordance with the method previously described inra highly dispersed phase of solids. In chamber 111 the gasification or conversion of the unconverted or partially converted coal from chamber 38 is substantially completed in a pseudo-liquid dense phase of solids.` By such an operation the first stage conversion of the coal is effected when the tendency for ag- `glomeration and settling of the finely divided coal is greatest but in a manner in which the least opportunity for agglomeration is afforded. After partial conversion of the iinely divided coal and Iremoval of many of the volatile components, the coal is then transferred to the pseudo-liquid dense phase 112 at a time when the tendency for agglomeration andsettling of the coal is the least. This method of operation also substantially lessens the length of reactor necessary since only a portion of the conversion or gasification is eliected in combustion chamber 38 while the carbon-containing material is transferred to chamber 111- for completing the gasification thereof. Solids from the pseudo-liquid dense phase 112 may be removed from chamber 111 through conduit or standpipe 114 and recycled to burner 37 and chamber 38. A cyclone separator (not shown) may be located inside chamber 111 to separate the coarser unconverted coal particles from tine ash. The fine ash is allowed to pass out .with the gas in'conduit 39, or with the solids in conduit 114.

The gas velocity in chamber 111 is below about 8 feet per second and lgenerally between about 0.5 and about feet per second. The concentration of solids in the pseudo-liquid dense phase is several times greater than the concentration of solids in combustion chamber 38 and generally the concentration is in accordance with the previous description of the pseudo-liquid dense phase. An upper dilute phase is present above the pseudo-liquid dense phase 112. A gaseous eflluent comprising hydroigen, carbon monoxide, and iine ash is removed from the upper portion of :chamber 111 and passed to boiler 54 through conduit 39. The cooled effluent is processed in a similar manner and with similar apparatus as described with reference to Figure l and therefore further discussion of the operation thereof is deemed unnecessary.

The arrangement of apparatus of Figure 2 is particularly suitable for low temperature operations required for producing amethane-rich gas since it allows more time for conversion.

Figure 3 illustrates another embodiment of the present invention in which steam is passed through conduit 121 and iinely divided coke is picked up from conduit 134. The pulverizatio-n and :coking process in chamber 128 from which the iinely divided coke is obtained will be discussed more fully hereinafter. Coke and steam are passed at a pressure, for example about 300 pounds per square inch gage,l to an elongated chamber 123 positioned horizontally or vertically. Finely divided coke and steam pass into burner 124 in which oxygen and steam are introduced through conduit 126. The resulting mixture of steam, oxygen, and finely divided coke under the previously recommended conditions of temperature, pressure, velocity, etc., of chamber 38 of Figure l, is combusted in :combustion chamber 123 in a dispersed phase method of operation to produce a carbon oxide and hydrogen. The combustion eiuent is passed from combustion chamber 123 through conduit 127 to the lower portion of Ia second enlarged chamber 128 which is positioned vertically. Crushed coal is introduced into hopper 136 through conduit 137 and is pressured by a gas introduced therein through conduit 138. Hopper 136 may comprise a series of lock hoppers, in accordance with the description of Figure 1, in order toV maintain the coal at the desired high pressure. Coal under a pressure of about 500 to about 600 pounds per square inch gage is passed from hopper 136 through conduit 139 and is introduced into conduit 127 or directly into chamber 128 through conduit 142, as shown. The coal and gas mixture from hopper 136 is expanded through either nozzle 141 or nozzle 143, or both, with a pressure drop of about 100 to about 300 pounds per square inch under conditions such that coal is pulverized to a size less than about 250 microns, preferably less than about 100 microns. This linely divided :coal is suspended in an upward owing gaseous mixture in chamber 128 under conditions such that a pseudo-liquid dense phase of coal indicated by numeral 129 is formed therein. Both oxygen and steam may be introduced into chamber 128 by means not shown, if desired. The temperature of chamber 128 may be substantially the same or lower than the temperature of co-mbustion chamber 123 and at the temperature existing therein, for example about l000 F., the finely divided coal is converted to coke with the resulting volatilization of the volatile components `of the coal. The coke formed in chamber 128 and present in the dense phase 129 is withdrawn therefrom by meansr of standpipe 134. A small amount of the coke may be withdrawn through conduit 135 to prevent the building up of ash in the system. Alternatively or additionally to the withdrawal of coke through conduit 135 a certain amount of iine ash may be permitted to pass out kof chamber 128 with the gaseous eiiiuent through conduit 123. The remainder of the coke not Withdrawn through conduit 135 is introduced into conduit 121, as previously described. A relatively dilute phase is present above the pseudo-liquid dense phase 129. The gaseous etlluent of the dilute phase passes through a cyclone separator 131 in the upper portion of chamber128' toremove entrained tinely divided solids therefrom. These iinely divided entrained solids collected in cyclone separator 131 may be returned to the pseudo-liquid dense phase 129 through conduit 132, as shown, or may be removed from chamber 128 for disposal, etc. A gaseous Veffluent from combustion chamber 123V comprising hydrogen, carbon monoxide and volatile components of the coal, such 'as tars, naphthalene, anthracine, benzol, toluol, phenol, cresol, xylol, and normally gaseous and liquid hydrocarbons las well as some nitrogen and sulfur compounds, is removed from the upper portion of chamber128 through conduit 133 and passed to a :conventional product recovery system (not shown) for the removal of the valuable organic compounds from the gaseous eiuent.

A modification of the system of Figure 3 will be briey described with reference'to Figure 4, in which moditication the distillation of the volatile components from the coal, as in chamber 128, is accomplished in a high velocity system similar to the system for the gasication of the coke in chamber 123. Thus, the reaction effluent from combustion chamber 123 is passed through conduit 127 to a volatilization chamber 151 comprising a cylindricalelongated conduit which may be positioned either horizontally or vertically. Pulverized coal is introduced into conduit 127 through conduit 139, as previously described. The heat of the reaction eiiiuent in conduit 127 volatilizes the volatile components of the coal in chamber 151 and the resulting mixture of hydrogen, carbon monoxide, volatile components of the coal, and coke are passed from chamber 151 through conduit 152 to separator 153 comprising a settling chamber or a :cyclone sepvarator. In separator 153 the coke is removed therefrom by gravity and passes through a standpipe 154 to conduit 121 for circulation to combustion chamber 123 of Figure 3 in the manner previously described. The reaction efliuent comprising carbon monoxide, hydrogen, and the previously mentioned volatile components and substantially free from coke is removed from the top of separator 153 through conduit 156. A small proportion 'of the coke in standpipe 154 may be removed through conduit 157 in order to prevent the build up of ash in the system. The primary :dierence in the modification of Figure 4 from that of Figure 3 is that the 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 8 feet per second,

without the formation of the conventional pseudo-liquid A dense phase of solids in the volatilization zone but forming instead Ia relatively dispersed or dilute phase having a concentration of solids in the range described previously with regard to chamber 38 of Figure l. In this manner of operation of the coking chamber, opportunity for the sticking and agglomeration of the particles is minimized or substantially prevented.

The embodiment illustrated in Figures 3 and 4 of the drawing is particularly yadapted to the recovery of volatile components of the coal and to the production of a high heating value gas. It may be desirable, therefore, to introduce a stripping gas into chamber 153 or conduits 134 or 154 by means not shown to aid in the removal of volatile 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 127 through conduit 139 or into chamber 128 through conduit 142 in a size larger than that used in vgasiiication of the coal in chamber 123. For example, crushed coal having an average diameter less than about 0.5'inch is introduced through conduits 139 and 142 without the use of

nozzles

141 and 143. In such a case the pressure of the coal in hopper 136 is substantially the same as the pressure existing in conduit 127 and :chamber 128. The pseudo-liquid dense phase 129 ness forfthe gasification of the coal.' The'pressure' in Y chamber 128 or chamber 151 and standpipe 134 is less lthan the pressure existing in conduit 121, and, therefore,

additionalmeans must be supplied,such as lock hoppers, etc., to 4introduce the coke fromconduit 134y or 154'finto conduit 121. l 'i' y 'f In still another modification of the' process of Figures 3 and 4, the reaction euent from combustionchamber 123`fmay be cooled such that the reaction is effected in chamber 12,8 orchamber 151 at a lower temperature than infcombustion chamber 123. A cooler or waste heat fboiler (not-shown) may be inserted in conduit 127 tocoolthe gaseous'v ellient-asmuch as 200 F. or 300 For even more,- prior to introduction of the effluent in to chamber 128 or chamber 151. f In this "marmer the operation of the `volatilization lstage at alower temperature prevents cracking- `of the rvolatile components and i1'1' creases lthe-recovery of highboiling products. fFigureS diagrammatically illustrates another embodi-l ment of `this invention for the lgasification offcoal.v In this embodiment a mixture of steamV and nely'divided coal or coke of thetypel previously described for use-in the gasification process is passed through conduit 171, burner'172, to gasification or combustion chamber f174 Oxygen and steam are introduced intol burner 172 vthrough 'conduit 173. The gasificationof coal is parf -tially effected in chamber 174 under the previously` described conditions of operation using a relatively lhigh 1'4 l is removed from chamber 181 through conduit 184 and passed to conduit 176 whereit is combined with the reactionfeiuent from conduit 174. yAlternatively, or additionally, all'or a-portion of the reaction effluent from chamber 181 mayffbe passedthrougha conduit 186 to conduit 171er directly into chamber 174.

The modification of Figure 5 permits treating the partially converted coal in chamber 181 with a large part of the fresh steam and oxygen, undiluted with product gases. *It Carbonaceous residues which are unconverted in chamberw174 because of the shortresidence timeare converted in chamber 181 wherel a relatively longer residence time is obtained. Unconverted, oxygen, and what wouldotherwise be an excessive lamount of uncony verted steam, may pass overhead from chamber 181 to chamber174 through conduit 186. These-:unconverted agents .are usefully consumed in chamber 174 because` they are therein subjected to contact with coal containing its reactive volatile components. 1 In effect this separates the..process.into,two stageswith provision .forl countercurrent treatment yas..between the two stages:

Three or more such stages might be used in special in# velocity of gas such that a pseudo-liquid dense phase"- is not formed in chamber 174 and such that the-residence timeof the iinely divided coal is preferably approxif mately the same as the residence time of the gaseous mixture passingl therethrough. According to this embodiment only partial gasication of the-coal is' effected in chamber l',174 and4 the unconverted coal is removed therefrom with the gaseous effluent through conduit 176 andpassedkto'separator 177. Separator 177 may com? prise a single or a series of conventional separators, lsuch as' settling"y chambers, Cottrell precipitators, cyclone separators,je'tc., for separating unconverted" co'alfrom the gaseous 'efduent of hydrogen and carbonin'onoxide, The gaseous effluent of hydrogen and carbon monoxide is withdrawn from separator 177 through conduit 178 for storage or use as a fuel or for the synthesis of organic compounds therefrom. Separated coal or' carbon-con-y taining material is removed from separator 177 through conduit 179- and passed to an enlarged chamber-181. Enlargedrchamber 181 isV of such size with? respect to the gaseouseiuent lpassing upward therethrough thatthe coal issuspended in a pseudo-liquid dense phase, as pref Viouslydescribed. A pseudo-liquid phase of solids can beusedsatisfactorily atthis point in the system because the partial conversion iny chamber 174 has reduced the tendency of the solids to agglomerate. Oxygen and .steam are introduced into chamberf181 through conduit '182 inthe appropriate proportions for converting the remainl ing unconverted or partially converted coal to hydrogen and carbon monoxide. The conditions of operation of chamberl 18,1 are similar to the conditions of operation of chamber 174 and may be varied within limits to achieve the desired result. Thegas velocity, of course, will be substantially lower. than" the gasnyelocity:r in chamber .17,4 and usually lower4 than about v6 feetv'per second; for example, about 2 feet perfsecond. A portion of, thefp'seudo-liquid dense phase may be removed from chamber 181 through conduit -or standpipe 183 in order `togpreventfthe building up of. ash in the system.v The reaction efluent`cfhydrogen`and carbon monoxide stances. By operating Vin .this.manner,. the temperature in'zone 174 may be appreciablyreduced so .that the production of, methane is favored and the temperature'in chamber 181 may be several hundred degrees higher than in chamber 1574.

Although the gures of the drawings havebeen described with,y reference to the explosionV pulverization method "for obtainingl the desiredlneness ofyvcoallfor gasication,y other methods for obtaining a iin/ely divided coal,` suchas ball` milling, and crushing-andl may be used without departing from the scope of this invention. In such instances where the coal is pulverizedby ball milling or otherwise prior to introduction into the system, the various nozzles maybe omitted andthe expansion of Athev gaseous mixture.4 containing the coal also eliminated. However, it may be desirable to combine the two processes; `that is, using a relatively finely di- VidedK-coal'fbelowy 250 microns in diameter and atthe same timeexplosiQnpulverize thisv finely divided coal to obtain evenfmore nely divided coal.Y Inplace .of the lock hoppers or standpipes shown in the drawing, a Fuller-Kinyonpu'mpor other screw conveyor device may befu'sedwithout `departing from the scope of this invention. Evencertain types of reciprocating pumps may be used'to introduce l,the coal into the system, such as those used on Stoker-fired furnaces. Another method of bring` ingy the coal feed vto' the operatingfp'ressureof, the process comprises mixing 'the' coal with water to form a slurry andhpumping the slurry to the `desired pressure with a conventionalslurry pump. The bulk of the slurry water is separated from the pressured y coal byy settling, etc., and thetliickened -slurry is preheated j to such an 4extent that the water flashes to'steam during the explosionpulverization." "Liquid oils may be used in place of water. l

In the embodiment lofiFigures 3 and 4,n thecoke` produced 'inl chambers"129 and 151, respectively, maybe recovered as a product ofthe process. 'In'such instances coke is :withdrawn 'through' conduits 135 and 157, "re- .SP'CtVelY i i l ,"It is usually necessary to aerate the'standpipes inthe process yto maintain thev iinely dividedsolids in the stand-y pipes ina fluidized condition in' order that the solids will ,flows The standpipes maybe 'conveniently aerate'd by i Y EXAMPLE Approximately 400 tons' per day of Illinois vcoke breeze lscharged to a combustion zone similar in constructlon 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 Y Weight percent The Illinois coke breeze is reacted with oxygen and steam in a high velocity combustion chamber at 'a nal temperature of about 1800 F. and at a pressure of about 285 pounds per square inch gage. The following quantities of steam and oxygen are consumed as` shown in Table II below.

I. Table Il Steam 500 p.s.i. gage and 750 F. 12,000 pounds/hr. Steam 300 p.s.i. gage and 1400 F 22,500 pounds/hr. 95% purity oxygen 800 F. 5,000,000-s.c.f./day. Steam (total) 1.03 pounds/pound coke. Oxygen Y(pure) 6.9 sci/pound coke.

The coke breeze is pulverized by means of explosion pulverization to obtain the necessary particle neness. The coke feed, initially crushed to 8 or 10 mesh, along with the 500 poundk steam which is in the amount of about 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 df the coke isy within the approximate range of 65 to 95 percent through a 200 mesh screen. The 300 pound steam and oxygen are admixed with the expanded steam and coke. The initial concentration of cokein the combustion chamber on 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 operating pressure and temperature of. 1800 F., the concentration is approximately 0.2 pound per cubic foot of gas. 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 llowing condition is about 0.045 pound per cubic foot of gas. Since the relatively low solids concentration ismaintained 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 cokeare small enough to be converted in the single pass through the combustion chamber. The coarser particles in the combustion chamber eluent which may contain au average of about 30 weight percent 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 type 309 Alloy (25 percent chromium; l2 percent nickel steel) surrounded by a layer of Baldwin-Hill type #5 block insulation approximately 3 inches thick.

The combustion chamber efuent comprising hydrogen and carbon monoxide discharges into a Vertical fire tube Waste heat boiler of conventional design. This boiler absorbs 20,000,000 B.t.u.s per hour from the product gas and in so doing cools the gas from about l800 F. to about 1260 F. IIn this manner 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 eilluent from the first boilerto a temperature of about 710 F. The second boiler absorbs about 18,500,000 B.t.u.s per hour from the veluent and generates -about 22,500 pounds per hour of steam at 350 pounds per square inch gage pressure. This quantity of steamY produced in the second waste heat boiler is approximately the amount of 350 pounds steam required for the process. Any deciency in 350 pound steam 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 rst boiler.

The cooled eluent from the second waste heat boiler is introduced .into a cyclone separator. In this separator the larger fsolid particles containing unconverted carbon are removed from the eflluent. About 45 percent 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 percent of unconverted carbon. The ash in the recycled solids amounts to about 60 percent of the net quantity of ash in the feed. Unseparated solids in the eluent from the separator contain only about 5 weight percent of carbon. All of the ash entering the process is ultimately eliminated with the separator eluent. The gas analysis of the gaseous eluent on a dry basis at this point in the process is shown in Table III below and constitutes about 30,000,000- 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 sulfide 0.2

Total 100.0

The eliiuent 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 exa changer from a deareator 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 of heat and after cooling the etlluent gas to about 440 F.

From this last heat exchanger the cooled effluent is passed to a conventional baled scrubbing tower in which the'eluent gas is cooledkto a nal temperature of approximately F. to condense unconverted steam and to remove finely divided entrained ash.v The scrubbing tower is maintained at a pressure of approximately 275 pounds iper square inch gage. The scrubbing is accomplished by circulating a stream of the water slurry through an outside cooler and lover baies within the tower. A small amount of fresh water is pumped over ltwo conventional bubble-cap trays in the top section of the tower to wash back slurry entrainedfrom the baied section.

Carbon dioxide and hydrogen sulfide may be removed by water scrubbing in a subsequent tower. The analysis of the gaseous eluent 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 puriiied gas per day with a hydrogen to carbon monoxide mol ratioof about 1:1. The gaseous eluent is suitable for the direct synthesis of hydrocarbons Certain valves, coolers, heaters, pumps, accumulators, 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 fluid 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 drawings. The example and theory in connection with the invention are offered as illustrations and should not be construed to unnecessarily limit the invention. y

Having described my invention, I claim:

1. A process for the gasification of a caking type coal to produce a gas rich in carbon monoxide and hydrogen which comprises introducing nely divided fresh untreated caking type coal in suspension in a gaseous mixture comprising oxygen and steam into a rst reaction zone under conditions such that hydrogen and carbon monoxide are produced, maintaining the velocity of the gaseous mixture in said first reaction zone above 8 feet per second and suciently high such that said finely divided particles of coal continuously move in the direction of iiow of gases in said first reaction zone, converting at least about 10 percent but not all of said coal to hydrogen and carbon monoxide, removing unconverted nely divided coal from said first reaction zone and continuously passing same to a second reaction zone, suspending solid carbon-containing material from said first reaction zone in said second reaction zone in an upwardly iiowing gaseous mixture comprising steam and added oxygen, maintaining the velocity of the gaseous mixture in said second reaction zone suiiciently low such that a pseudo-liquid dense phase of finely divided solid carbon-containing material is formed, and recovering an eiiiuent from said reaction zones comprising hydrogen and carbon monoxide as a product of the process.

2. A process for the gasification of a caking type coal to produce a gas rich in carbon monoxide and hydrogen which comprises introducing iinely divided fresh untreated coal having a particle size less than 250 microns in diameter in suspension in a gaseous mixture comprising oxygen and steam into a first reaction zone under conditions such that hydrogen and carbon monoxide are produced, maintaining the velocity of the gaseous mixture in said first reaction zone above 8 feet per second and sufliciently high such that said finely divided coal particles continuously move in the direction of flow of gases in said first reaction zone without substantial caking, converting at least about 10 percent but not all of said coal to hydrogen and carbon monoxide, removing unconverted finely divided coal from said rst reaction zone and continuously passing same to a second reaction zone, suspending coal from said rst reaction zone in said second reaction zone in an upwardly flowing gaseous mixture comprising steam and added oxygen, maintaining the velocity ofthe gaseous mixture in said second reaction zone suiciently low such that a pseudo-liquid dense phase of iinely divided solid carbon-containing material is formed whereby coal is converted to additional hydrogen and carbon monoxide and recovering an eiuent from said reaction zones comprising hydrogen and carbon monoxide as a product of the process.

3. A process for the gasification of a caking type coal to produce a gasrich in carbon monoxide and hydrogen which comprises introducing finely divided fresh untreated coal having a particle size less than 250 microns in diameter in suspension in a gas mixture comprising oxygen and steam into a rst reaction zone under conditions such that hydrogen and carbon monoxide are produced, maintaining the velocity of the gaseous mixture in said firsty reaction zone above 8 feet per second and suiciently high such that said nely divided coal particles continuously move in the direction of flow of gases in said iirst reaction zone without substantial caking, converting at least about 10 percent but not all of said coal to hydrogen and carbon monoxide, removing unconverted nely divided coal from said iirst reaction zone and continuously passing same to a second reaction zone, suspending nely divided coal'from said first reaction zone in said second reaction zone in a gaseous mixture of added oxygen and steam whereby coal is converted to additional hydrogen and carbon monoxide, maintaining the velocity of the gaseous mixture in said second reaction zone sufficiently low such that a pseudo-liquid dense phase of nely divided solid carbon-containing material is formed, withdrawing unconverted coal from the dense phase of said second reaction zone and introducing same into said rst reaction zone, and recovering an effluent from said reaction'zones comprising hydrogen and carbon monoxide as a product of the process.

4. A process for the gasification of a caking type coal to produce a gas rich in hydrogen which comprises introducing finely divided fresh untreated coal, steam and oxygen into a rst reaction zone, maintaining the velocity of gases in said first reaction zone above 8 feet per second and suiiiciently high such that said iinely divided coal is continuously moved in the direction of flow of the gases, converting coal in said first reaction zone to hydrogen by reaction with steam, converting at least about l0 percent but not all of said coal to hydrogen and carbon monoxide, removing Aunconverted finely divided carbon-containing material from said rst reaction zone and continuously passing same to the lower portion of a second reaction zone, introducing steam and oxygen into said second reaction-zone whereby unconverted coal is reacted to produce additional hydrogen, maintaining the velocity of the gases in said second reaction zone suiiiciently low such that nely divided coal is suspended to form a pseudoliquid dense phase of finely divided solids in the upwardly owing gases, and recovering an effluent from said reaction zones comprising hydrogen as a product of the process.

5. A process for the gasification of a caking type coal to produce a gas rich in hydrogen and carbon monoxide which comprises introducing nely divided fresh untreated coal, steam and oxygen into a first reaction zone, maintaining the velocity of the gases in said first reaction zone above 8 feet per second and suiciently high such that said coal is continuously moved in the direction of iiow of the gases, exothermally converting coal in said first reaction zone to hydrogen and carbon monoxide by re action with steam and oxygen, converting at least about 10 percent but not all of said coal to hydrogen and carbon monoxide, removing unconverted finely divided coal from said first reaction zone and continuously passing same to the lower portion of a second reaction zone whereby unconverted coal ,is reacted to produce additional hydrogen and carbon monoxide, introducing additional steam and additional oxygen into said second reaction zone, maintaining the velocity of the gases sufficiently low in said second reaction zone such that finely divided coal is suspended to form a pseudo-liquid dense phase of iinely divided solids in the upwardly flowing gases, and recovering an eluent from said reaction zones comprising hydrogen and carbon monoxide as a product of the process. v

6. A process for the gasication of coal which comprises introducing finely divided coal into a lower portion of a iirst reaction zone, introducing oxygen and steam into the lower portion of said rst reaction zone whereby coal is converted to carbon monoxide and hydrogen, maintaining the linear gas ,velocity of gasesin said iirst reaction zone suiiciently high such that the particles of inely divided coal move in the direction of ow of the gases passing therethrough, converting at least about percent but not all of said coal to` hydrogen and carbon monoxide, removing from said first reaction zone a gaseous eiuent comprising hydrogen, carbon monoxide and iinely divided unconverted coal, separating unconverted coal from said gaseous efduent, passing separated unconverted coal to a second reaction zone, introducing oxygen and steam into the lower portion of said second reaction zone, maintaining thelinear gas velocity of the gases in said second reaction zone sufficiently low such that finely divided coal is suspended therein as a pseudo-liquid dense phase of finely divided solids, removing from said second reaction zone a gaseous eiliuent comprising excess oxygen and steam and products of reaction comprising hydrogen and carbon monoxide and introducing such eliuent into the lower portion of said first reaction zone.

7. A process forv the gasication of coal which comprises introducing nely divided coal into a lower portion of a iirst reaction zone, introducing oxygen and steam into said rst reaction zone, maintaining a linear gas velocity of gases in said rst reaction zone suciently ight such that the particles of finely divided coal move in the direction of flow of the gases passing therethrough, converting at least about 10 percent but not all of said coal to hydrogen and carbon monoxide, removing from said first reaction zone a gaseous eiuent comprising hydrogen and finely divided unconverted coal, separating unconverted coal from said gaseous eliuent, passing separated unconverted coal to a second reaction zone, introducing an oxidizing gas into the lower portion of said second reaction zone, maintaining the linear gas velocity of the gases in said second reaction Zone sufficiently low such that finely divided coal is suspended therein as a pseudo-liquid dense phase of iinely divided solids, removing from said second reaction zone a gaseous eluent comprising excess oxidizing gas and products of reaction comprising hydrogen and introducing such euent into said iirst reaction zone.

8. A process for the gasification of a caking type coal to produce a gas rich in hydrogen which comprises introducing nely divided fresh untreated caking type coal into aflrst reaction zone, introducing oxygen and steam into said 'first reaction zone, maintaining a linear gas velocity of gases in said first reaction zone above 8 feet per second and suiiiciently high such that said finely divided coal moves in the direction of flow of the gases therein, converting at least about 10 percent but not all of said coal to hydrogen and carbon monoxide, removing from said irst reaction zone an efliuent comprising hydrogen and unconverted coal, continuously passing said eiiiuent containing unconverted coal to the lower portion of a second reaction zone, introducing steam and oxygen into said second reactionzone, maintaining the linear velocity of gases in said reaction zone such that a pseudoliquid dense phase of solids is formed therein, and removing from said second reaction zone a gaseous eiiiuent comprising hydrogen as a product of the process.

9. A process for the gasification of-coal to produce a gas rich in carbon monoxide and hydrogen which comprises introducing iinely divided fresh vuntreated caking type coal into the lower portion-of la iirst reaction zone, introducing oxygen and steam into the lower portion of said iirst reaction zone under conditions such that coal is converted to carbon monoxide and hydrogen, maintaining a linear gas velocity of gases in said rstreaction zone above 8 feet per second and sufficiently high such that said iinely divided coal moves in the direction of ow of the gases therein, converting at least about 10 percent but not all of said coal to hydrogen and carbon monoxide, removing from the upper lportion of said irst reaction zone an eiuent comprising hydrogen, carbon monoxide and unconverted coal, continuously passing said eiuent containing unconverted coal to the lower portion of a second reaction zone, introducing oxygen and steam into said second reaction zone under conditions such that coal is converted to additional hydrogen and carbon monoxide, maintaining the linear velocity of gases in said second reaction zone such that a pseudo-liquid dense phase of solids is formed therein, and removing from said second reaction zone a gaseous eiiiuent comprising hydrogen and carbon monoxide as a product of the process.

References Cited in the ile of this patent UNITED STATES PATENTS 2,554,263 Nelson May 22, 1951 2,582,710 Martin Ian.'15, 1952 2,582,712 Howard Jan. 15, 1952 FOREIGN PATENTS 578,711 Great Britain July 9, 1946 OTHER REFERENCES Rubber Handbook, 33rd ed., pp. 1593, 1594.

Claims

1. A PROCESS FOR THE GASIFICATON OF A CAKING TYPE COAL TO PRODUCE A GAS RICH IN CARBON MONOXIDE AND HYDROGEN WHICH COMPRISES INTRODUCING FINELY DIVIDED FRESH UNTREATED CAKING TYPE COAL IN SUSPENSION IN A GASEOUS MIXTURE COMPRISING OXYGEN AND STREAM INTO A FIRST REACTION ZONE UNDER CONDITIONS SUCH THAT HYDROGEN AND CARBON MONOXIDE ARE PRODUCED, MAINTAINING THE VELOCITY OF THE GASEOUS MIXTURE IN SAID FIRST REACTION ZONE ABOVE 8 FEET PER SECOND AND SUFFICIENTLY HIGH SUCH THAT SAID FINELY DIVIDED PARTICLES OF COAL CONTINUOUSLY MOVE IN THE DIRECTION OF FLOW OF GASES IN SAID FIRST REACTION ZONE, CONVERTING AT LEAST ABOUT 10 PERCENT BUT NOT ALL OF SAID COAL TO HYDROGEN AND CARBON MONOXIDE, REMOVING UNCONVERTED FINELY DIVIDED COAL FROM SAID FIRST REACTION ZONE AND CONTINUOUSLY PASSING SAME TO A SECOND REACTION ZONE, SUSPENDING SOLID CARBON-CONTAINING MATERIAL FROM SAID FIRST REACTION ZONE IN SAID SECOND REACTION ZONE IN AN UPWARDLY FLOWING GASEOUS MIXTURE COMPRISING STEAM AND ADDED OXYGEN, MAINTAINING THE VELOCITY OF THE GASEOUS MIXTURE IN SAID SEOCND REACTION ZONE SUFFICIENTLY LOW SUCH THAT A PSEUDO-LIQUID DENSE PHASE OF FINELY DIVIDED SOLID CARBON-CONTAINING MATERIAL IS FORMED, AND RECOVERING AN EFFUENT FROM SAID REACTION ZONES COMPRISING HYDROGEN AND CARBON MONOXIDE AS A PRODUCT OF THE PROCESS.