US2554263A - Gasification of carbonaceous solids - Google Patents

Description

y 22, 1951 Y K J. NELSON 2,554,263

GASIFICATION OI? CARBONACEOUS SOLIDS Filed Dec. 18, 1946 3 Sheets-Sheet 1 KarL U. nelson w'lnn ow b Wdbbornig y 2, 1951 K. J. NELSON 2,554,263

GASIFICATION 0F CARBONACEOUS SOLIDS Filed Dec. l8, 1946 3 Sheets-Sheet 2 Karl U. nelson flaverz bor Q 335 Clbborrzeg Patented May 22, 1951 GASIFICATION F CARBONACEOUS SOLIDS Karl .LNelson, Granford, N. J.,assignor-to Standard Oil Development Company, a corporation of Delaware Application December 18, 1946, Serial No. 717,064

The present invention relates to the conversion of carbonaceous solids such as all types of coal, lignite, peat, oil shale, tar sands, coke, oil coke, cellulosic materials, including ligni-n, etc. into gases containing carbon monoxidesuchas-water gas, producer gas and the like.

Prior to the present invention,- it has been suggested to gasif carbonaceous solids with a gasifying medium such as steam and/or air to produce water or producer gas, in the form of a dense turbulent bed of finely divided solids having a particle size of about /4 to ,4 in. down to about/400 mesh, fluidized by anu-pvvardly'floW-ing gas and maintained at gasification temperatures of about l'500 2500 'F. This technique isgrea-tly superior to conventional fixed-bed operation -It provides, larger solid reaction surfaces, "better mixing and greatly improved temperature eontrol, and it afiords higher gas yields in-iullycontinuous operation within shorter reaction times.

While these great advantages make'the'application of-thefiuid-solids techniqueto coal gasification appear highly attractive it has not-as yet found the broad commercial -applica-tion it would seem todeserve. One of the more important reasons of 'the'slownessof this development lies in difficulties encountered int-he substantially complete'conversion of the carbon feed with the carbonaceous charge into product gas .and heatmequired -f or the process at reasonably constantconversion conditions, satisfactorysteam conversion rates, reasonable temperature -1evels andLeconomic equipment design.

Such substantially complete utilization of .the carbonaceous charge is 1 an essential condition :fQI' the economic operation of the coal gasification process. (On the other hand, the rate @o'fconv ersion of the gasifying medium in .the water gas as well as in the producer gas reaction decreases rapidly as the carbon concentration in theconversion zone decreases so that relatively ahigh carbon concentrations are necessary fortheproduction ,of satisfactory gas yields .atiazgiven temperature per unit of time and :reactor space.

In conventional fluid solidszoperation:theentire reacting mass of fluidized carbonaceous solidschas .tial combustion of the carbonaceouscharge within the fluid generator bed at high-carbon concentrations, a gasification residue of the same high carbonconcentration is withdrawn from the gas generator in continuous operation. This high-carbon residue must be reprocessed'in order to avoid carbon losses in the system. Gasificae tion to lowvcarbon concentrations at substantially constant conditions would require anexcessively large reaction space without completely avoid, ing the carbon losses in the/form of carbonaceous gasification residue.

Generation .of heat by combustion of highcarbon gasification residue ina conventional external burner and heat supply to .the generator in the form of sensible heat of combustion gases so produced require excessive amounts of heating gases in view of the high gasification temperatures to .be maintained in the gas generator and the temperature limitations imposed b the relatively low heat resistance of economical construction materials for conventional burners.

Ithas also been suggested to generate heat by the combustion of solid carbonaceous gasification residue in an external heater and'to supply ,heat to thegas generator in the form of sensible heat of solid combustion residue circulated from the heater to the gas generator. Eflicient combustion at high temperatures in'an external heater of this type requires low carbon concentrations to avoid excessiveair requirements and/or car- .bon losses in the form of CO formed by the ireduction of CO2 with excess .carbon. This ,reguirement .is incompatible with a high carbon concentration in the gas generator.

It will .be appreciated :from .the above that the reconciliation .of high carbon concentrations .in-.-a fluid gas generator with .a complete conversion of the-available carboninto gas-and heatrequired for the process presents an important .and "dimcult problem. The presentinvention isconcerned with means for solving this problem.

It is, therefore, an important object of this invention to providean improved process for producing combustible gases; from:carbonaceoussolids employing the fluid solids technique.

Another object of ;my in,vention is ,to provide :an improved process for :the gasificationnf -,carbona.- ceous solids in the form of a dense, turbulent, fluidized .bed of finely divided solids at optimum rates of conversion and with full utilization of availablecarbon.

Another object of this invention is to provide 3 improved means for supplying heat to a fluidized bed of finely divided carbonaceous solids undergoing gasification at optimum conversion rates by burning gasification residue in an external burner.

A more specific object of my invention is to provide improved means for supplying heat to a fluidized bed of finely divided carbonaceous solids undergoing gasification at optimum conversion rates, full utilization of available carbon in the process and convenient disposal of ash.

Other and more specific objects and advantages will appear hereinafter.

In accordance with the present invention, finely divided carbonaceous solids are subjected in a gas generation zone to a gasification reaction with a gasifying medium at gasification conditions of temperature and pressure, in the form of a dense turbulent bed of finely divided solids of substantially uniform and high carbon concentration conducive to highest rates of conversion of the gasifying medium used. Solid finely divided gasification residue having the average carbon concentration of the gasifi'cation bed is burned in a separate combustion zone at temperatures above the melting point of the ash of the carbonaceous charge, that is, about 2000-3500 F., preferably 2700-3300 F. and at an oxygen supply at least sufficient to permit complete combustion of the carbon introduced into the combustion zone. Liquid ash may be withdrawn from the combustion zone while flue gases are supplied to the fluidized solids bed of the gasification zone substantially at the extremely high temperatures of the combustion zone to supply at least a portion of the heat required by the gasification reaction. Low-carbon solids carry-over from the combustion zone to the gas generation zone is substantially avoided by the fusion and liquid drawoif of the ash in the combustion zone.

Complete combustion of the carbon supplied as gasification residue to the combustion zone normally requires a considerable excess of oxygen to be supplied to the combustion zone. This excess oxygen enters the gas generator as a con- Since reaction (1) is very fast, reaction (2) relatively slow and reaction (3) of intermediate speed the desired gas composition may be established by adapting the contact time of solids and gases at any given gasification conditions of temperature, pressure, carbon concentration, reactivit of the solid charge and steam to oxygen ratio to the requirements of either reaction (2) or reaction (3) either of which requires contact times sufficiently long to allow for the completion of reaction (1) and foroptimum utilization of the heat obtained from the'latter. Adaptation of the contact time to-the requirements of the slowest reaction (2) will permit the formation of sufficient CO2 to generate the heat required while permitting a reduction of CO2 formed to establish the desired minimum CO2 content of the final product In this manner, the gasification reaction may be conducted at optimum carbon concentrations and conversion rates at relatively low conversion temperatures while all available carbon not converted in the gas generator is utilized for heat generation rather than lost as it would be if the gasification were carried out at similar gasification conditions but without the use of my external combustion zone. An additional advantage of my invention results from the fact that gas-generating equipment for high-carbon, low-temperature operation is more economical with respect to size and cost of construction materials than equipment for low-carbon and/or high-temperature operation.

The extremely high combustion temperatures required for the purposes of my invention may be produced, for example as has been recently shown, by passing a suspension of finely divided carbonaceous solids in a combustion-supporting gas such as air and/or oxygen tangentially along the axis of a cylindrical combustion zone thereby imparting a rotating motion to the suspension, if desired, aided by a gas, preferably secondary combustion-supporting gas, introduced tangentially into the combustion zone at a high velocity of about 200-800 ft. per second to bring the total oxygen supply to about -600% of the theoretical. However, it is only necessary to supply that amount of oxygen to the combustion zone, which is required to burn the carbon therein substantially completely while any excess oxygen thereover may be by-passed and admitted directly to the gas generator. The secondary combustionsupporting gas may amount to as much as about 98% of the total combustion-supporting gas supplied to the combustion zone. The combustion zone may be either substantially vertical or substantially horizontal with a tilt downward toward the discharge end to facilitate the flow and tapping of liquid ash. Instead of secondary combustion-supporting gas steam, CO2, or the like may be used as the gas introduced tangentially if the amount of primary combustion-supporting gas is high enough to satisfy the requirements of the process.

In operation, a violent swirling action takes place within the combustion zone due mainly to the tangential velocity of the secondary gas and to some extent to the rotary motion of the solidsin-gas suspension fed axially. As a consequence of centrifugal force, the internal walls of the combustion zone are covered with a film of molten ash which travels in a spiral manner and eventually discharges at the lower end of the combustion zone. The larger carbonaceous particles are caught in the slag film and burned by the combustion-supporting gas passing by at higher velocity, while the smaller particles burn in the gas zone. The fines burn almost instantaneously in the vortex to which a small volume of tertiary combustion-supporting gas, amounting to about 1-5% of the total combustion-supporting gas, may be fed to accelerate this combustion.

The combustion chamber may be a steel cylinder lined with refractory such as chrome ore or the like. Since the sintering or melting points of even the most heat resistant refractory linings usually lie substantially below the prevailing combustion temperatures, cooling tubes are pref erably imbedded in the lining.

The temperatures reached in a combustion zone of this type when pure or concentrated oxygen is used as the combustion-supporting gas are substantially higher than those required to establish an efficient temperature differential between the combustion zone and the gas generation zone. In actual operation I prefer, therefore, to use air or :oxygen diluted with steam or flue gases as the combustionesupporting gas the proper choice of which depends on the type of gasification reaction desired. When producer gas is to be manufactured in the gas generation zone, air is a suitable diluted combustion supporting gas while for the production of water gas oxygen diluted with steam is preferred.

As mentioned above, the external combustion zone is normally operated with an excess of oxygen so that unconverted oxygen becomes available for conversion and/or heat generation within the gas generation zone. For the generation of producer gas this excess of oxygen may be chosen high enough to supply, in combination with the CO2 content of the flue gas, all the oxygen required in the gas generation zone to convert the desired amount of carbon into carbon monoxide. When water gas is produced, part .or all of the steam .required for the water gas reaction may serve as a diluent .in the combustion zone and the excess oxygen from the combustion zone may be used in the gas generation zone to generate additional heat therein substantially as outlined above. Some steam dissociation and/or conversion may take place at the conditions of the combustion zone and any hydrogen and/or carbon monoxide produced in this manner will be recovered from the gas generator.

In accordance with a more specific embodiment of the invention, a combustion zone of the type described may be combined with a conventional. fluid heater to supply heat to the gas generation zone in the form of sensible heat of solid heater residue. For this purpose solid gasification residue of relatively high carbon concentration may be circulated from the fluidized gas generator bed to an external heater wherein it is subjected to a combustion with air in the form of a dense, turbulent, fluidized bed at relatively high carbon concentration. A major portion of the solid, relatively high-carbon combustion residue from the heater may be returned to the gas generator for heat supply therein. A minor portion may be passed to a high temperature combustion zone of the type described above to completely burn the carbon, dispose of the ash and produce flue gas having a temperature far in excess of the temperature in the heater. This flue gas is returned to the heater.

The CO2 introduced into the heater with the flue gases from the combustion zone will, at the high carbon concentration of the heater, react with carbon to form CO, causing losses of heat and effective carbon unless sufficient oxygen is present in the heater to favor the formation of CO2 over that of 00. It is advisable, therefore,

to maintain, for example, at least a slight excess of oxygen in the heater over that consumed by the desired combustion of solid carbon in the heater. This may be accomplished by splitting the air feed to the system in a suitable manner and feeding part of the air to the high' temperature combustion zone and part to the heater, if desired, in a plurality of streams.

In this manner, the heater temperature and thus the temperature differential between heater and gas generator may be maintained at least at similar and even at higher levels as if carbonaceous solids of low carbon concentration were burned in the heater. However, the carbon concentration of the heat-carrying solids returned to the gas generator is now high enough to establish a carbon concentration within the gas generator at levels desirable for high con- '6 version rates. In this, as in the embodiment operating without solid heat carrier, the total available carbon is eventually converted into product gas and heat required for the process and the ash is effectively disposed of.

Having .set forth its objects and general nature, the invention will be best understood from the more detailed description hereinafter in which reference will be made to the accompanying drawing wherein Figure l is a partly schematical partly diagrammatical illustration of a system utilizing the sensible heat of high temperature flue gases as a source of heat for the gas generation reaction,

Figure 2 is a similar illustration of a system using the sensible heat of high temperature solids for the same purpose, and

Figure 3 is a semi-diagrammatical illustration of a high temperature combustion chamber suitable for the purposes of the invention.

Referring now to Figure l, the system shown therein essentially comprises a water gas generator i0 and a high temperature combustion zone or burner 40 whose functions and cooperation will be forthwith explained. While low temperature coke will be referred to hereinafter as the carbonaceous solid used any other solid carbonaceous material may serve as charge to my process.

In operation, a finely divided preferably highly reactive coke produced by the carbonization of a bituminous coal in a fluidized solids bed at temperatures not substantially exceeding 1000 F. is supplied through line i to gas generator i=3. Line 5 may be part of any conventional means for conveying finely divided solids such as an aerated standpipe, a pressurized feed hopper, a mechanical conveyor, etc. The particle size of the coke may fall within the wide ranges of in. to 400 mesh, preferred size ranges being about as follows:

40-60% through 30 mesh screen,

til-100% through ,4; in. screen The finely divided coke forms in generator it! above distribution grid l2 a dense turbulent mass M of solids fluidized by the gaseous reaction products and the gas and vapors supplied through line it and grid i2 as will appear more clearly hereinafter. Linear gas velocities of about 01-10 ft. per second, preferably 0.3-3 ft. per second, within mass Hi are generally suitable for this purpose at pressures ranging from about atmospheric to. about 400 lbs. per sq. in and for bed densities of about 10-50 lbs. per cu. ft.

Heat and gasifying medium such as air, oxygen and/or steam, depending on the product gas desired, are supplied through line It sufficient in amounts to maintain bed It at the desired gasiflcation temperature of about 1400 2500 F. and at a carbon concentration of about I! provided with solids return line I9. Gases substantially free of solids leave through line 2| and flow to further processing equipment and/or any desired use such as a hydrocarbon synthesis reactor 01 the like (not shown), if desired, after heat exchange with solid and/or gaseous feed materials of the process.

Solid fluidized gasification residue of the average carbon concentration of bed I4 is withdrawn downwardly through well 23 and passed under the combined pseudo-hydrostatic and gas pressures of bed I4 through standpipe 25 to which a small amount of steam, air and/or oxygen is added through taps 29 to facilitate the flow and strip the solids in standpipe 25. The rate of solids flow through standpipe 25 is adjusted by means of valve 21. A solids withdrawal rate of about .05 to 0.3 lb. per lb. of coke charged through line I is generally adequate.

carbonaceous solids discharging through valve 21 are suspended in a stream of combustion-supporting gas such as air and/or oxygen flowing through line SI and the suspension formed is blown into burner 40, preferably tangentially, along its axis. The amount of air and/or oxygen entering burner 40 through line 3| including any combustion-supporting gas admitted through taps 29 may be about 1-20% of the total combustion-supporting gas supplied to burner 40. The remainder of the combustion-supporting gas required to bring the total amount of gas above 100%, say, to between about 105 and 600% of the amount theoretically required for complete combustion of carbon available in burner is supplied through a manifold 42 or the like, tangentially to the combustion zone of burner at a linear velocity of about 300-700 ft. per second, preferably about 500 it. per second. Details of the design of burner 40 will be described below in connection with Figure 3 of the drawing. It should be noted, however, that burner 40 may also be arranged in a substantially vertical position with a downward flow of feed and ash.

The temperature of burner 49 is maintained above 2500 the desired temperatures depending on the fusion point of the ash and the amount of carbon to be burned. Liquid ash is tapped at 44 while hot flue gases enter line I6 and generator l0 substantially at the temperature of burner 40.

When water gas is to be produced in generator ill by a gasiflcation reaction with steam, oxygen may be supplied as the combustion-supporting gas through lines 3i and 42. In order to prevent the temperature within burner 40 from rising beyond desired levels, at least a substantial proportion of the steam required for the water gas reaction may be admitted through lines 45 and/or 52 to burner 40 to act as a diluent of the oxygen. Any additional steam required to bring the total up to 0.4 to 4.0 lbs. per lb. of coke charged as it is needed for the desired gasiflcation may be added through line 43 directly to generator l0. Burner temperatures of about 2700-3300 F. are generally suitable for most of the conventional carbonaceous charge materials. Excess oxygen entering generator if) burns an equivalent amount of combustibles in bed 14 to generate additional heat therein. In general, a

total of 0.2 to 2.0 lbs. of oxygen charged to the burner per lb. of carbon to be gasified is sufficient for the production of water gas.

When generator 10 is to be used for the manufacture of producer gas, air instead of oxygen is supplied through lines 3| and 42 and the temperature in burner 40 is controlled by the excess of air, part of which may be admitted through line 46. Additional air required for gas generation in bed i4 may be supplied through line 48. The amount of total air required for the manufacture of producer gas may fall within the approximate limits of 1.5 to 6.0 lbs. per lb. of carbon to be gasified.

Instead of feeding the carbonaceous charge through line i directly to bed l4 it may be suspended in the gasifying medium flowing through line [6 or line 48 and passed upwardly through grid I2 in a manner known in the art of fluid solids handling.

Referring now to Figure 2, the system shown therein essentially comprises a gas generator 2H1, a fluid solids heater 230 and a high temperature burner 240.

Finely divided fresh coke is charged through line 20! to generator 210 to form therein above grid 2I2 a dense turbulent bed of solids fluidized by gas supplied through line 2H; and forming an upper level M5 to undergo gasification substantially as described in connection with generator iii of Figure 1. Product gas is withdrawn upwardly through gas-solids separator 2 :1 provided with solids return line H9 and thence through line 22L High-carbon gasification residue flows through solids withdrawal well 223 and standpipe 225 provided with control valve 22'! and aerated and stripped through one or more taps 229 with air and/or oxygen to heater 230 to form therein above grid 232 a dense turbulent bed of carbonaceous solids fluidized by hot air and flue gas suppiied through line 233 to form a well defined upper level 234. Linear gas velocities and bed densities in heater 230 may be substantially the same as those specified in connection with generator ID of Figure l.

The amount and distribution of air supplied to heater 230 should be sufficient to prevent substantial reduction to C0, of CO2 present in heater 230 including CO2 contained in the hot combustion gases issuing from burner 240 and entering 230 through lines 245 and 233 as will appear hereinafter. Proper distribution of the air fed to heater 230 may be accomplished by the use of one or more manifold branch lines 233a, depending on the height of the fluidized bed in heater 230.

The combined effect of combustion and high oxygen supply raises the temperature of the solids in heater 230 to temperatures of about 15O0- 500 preferably about 1700-1900 F., that is, below the fusion point of the ash but substantially above the desired gasiflcation temperature in generator bed 214. Flue gases are withdrawn overhead from level 234 through cyclone separator 235 and pipe 236 to be used for any desired purpose including heat exchange with process solids and/or gases. Solids separated in separator 235 may be returned through pipe 23'! to heater 230.

Solid fluidized combustion residue from heater 230 is withdrawn through standpipe 238 and passes substantially at the temperature of heater 236 through branch standpipe 24| into line 2H3 where it is suspended in the gaseous gasifying medium and carried through grid 2I2 into generator '2) to supply the heat required for gasiflcation. As a result of the high temperature and high carbon concentration of the solids so supplied, the carbon concentration in generator 2m remains as high as about 15 to preferably about 30 to 56%, at gasifieation temperatures of about 1400-2500 F. Solids circulation rates through standpipe 2 of about. 50. to 500 lbs. per lb. of carbon to be gasified are generally sufficient. for this purpose at the conditions indicated.

A minor proportion of the. solids entering standpipe 238 is branched off to standpipe 233 and fed to line 23! wherein it. is suspended in air and thence supplied to burner 24!} for complete combustion at temperatures above the ash fusion point. substantially as outlined in connection with burner 40 of Figure 1. Secondary high velocity air is admitted tangentially through manifold 242 to bring the total combustion air above the amount theoretically required for complet combustion. Liquid ash is withdrawn through tapv 2.44 and .hot flue gases pass at a temperature of about 25009-3300 F. through lines 2 1.5. and 233to heater 2% as outlined above.

It will be understood that the amount of solids circulated through standpipe 225 will depend on the feed rate of carbonaceous charge.

and the rate of solids circulation through standpipe 2:3! and pipe Zlfiso that major fluctuations of level 2 !5 will be avoided. For similar reasons the rate of solids withdrawal through standpipe 238 will depend on the rate of solids supply through standpipe 225. In general, solids circulation rates through standpipe 225 of about 50 to 560 lbs. per lb. of coke charged through line Zfii and or" about 49 to 499 lbs. through standpipe 233 per lb. of coke charged through line 20! are adequate for the purposes of the invention.

The exact reaction conditions in generator 256 depend on the kind of product gas desired. For the production of water-gas, steam is supplied through lines 216 and temperatures of about 14001900 F. and pressures of atmospheric to about 400 lbs. per sq. in. may be used, th higher pressure ranges being conducive to the formation of a high B. t. 11. gas rich in gaseous hydrocarbons. For the manufacture or" producer gas the same or higher temperatures,

say 2.0002400 R, and similar pressures may be applied while predominantly air, if desired, admixed with some steam is supplied through line 286.

If desired, additional heat may be supplied togenerator 2m in the form of hot, normally oxygen-containing burner flue gases branched off line 2% to lines 247 and 215, or a combustionsupporting gas such as air and/or oxygen may be added to generator 2E8 through line Zi5- or 248 to support a limited combustion within bed 2M.

It will be understood'that in place of any one or all of standpipes 225, 238, 2 and 243 other conventional means for conveying fluidized solids such mechanical conveyors of various types may be used. It should also be noted that heater 23% may be arranged at higher level than generator are so that solids flow is by gravity from heater 236 to generator 2H] and by way of combined gas and pseudo-hydrostatic pressure in the opposite direction As stated before, burner 24E! may also be arranged in a vertical position. Other modifications within the scope of my invention will appear to those skilled in the art.

Referring now to Figure 3, I have illustrated therein in greater detail a high temperature burner of the type schematically shown at 49 and 240 of Figures 1 and- 2 respectively. While the general principles of design and operation of burners of this type have been suggested by others prior to the present invention their specific adaptation to the gasification of car-- bonaceous solids employing the fluid solids technique forms an essential element of the present invention.

Th burner, as illustrated, may consist of an outer steel shell 3% provided with an inner refractory lining 35E? preferably of chrome ore having a fusion point not substantially below. 2700 F. Cooling tubes 352 are imbedded in the refractory lining and supplied with cooling water through water header 35d. Heated water and/ or steam is withdrawn from the cooling tubes 352 through header 356. Manifold 324, preferably in the. top of the combustion zone, serves the introduction of high velocity secondary com.- bustion-supporting gas and/or diluent.

carbonaceous solids having a particle size substantially as described above are supplied from the gas generator or heater through standpipe 353. About 1-l5% of the total combustionsupporting gas required may be added through. tap 339. The fluidized solids flow under the pressure of standpipe 3:33 to feed device 35.8 arranged on thehorizontal axis of cylindrical. shell 340. An additional amount of about 1-5% of the total combustion-supporting gas may be added through line 33 l.

The solids-gas mixture enters shell 3% tangentially along the axis, a more violently rotating motion being imparted to the combustion mixture by the tangential high velocity secondary combustion-supporting and/or diluent gas supplied through 324, which may amount to as much as 98% of the total combustion-supporting gas. The burner is operated above ash fusion temperature and liquid ash is withdrawn through a bottom orifice 344 close to the lower discharge end of the burner. Hot flue gases are withdrawn through port 345 for further use in the process, preferably after passing through an entrainment separator wherein entrained fluid ash may be removed in any conventional manner.

The violent swirling action of th combustion mixture causes an extremely intimate contact between fuel and combustion-supporting gas and makes possible the attainment of extremely high combustion temperatures in a relatively small combustion space. Ihe cooling tubes 352 are operated so as to maintain the refractory lining in an effective operating condition, while withdrawing only a minimum amount of heat from the chamber.

The absolute dimensions of the burner depend, of course, on the output desired. It may be stated, however, that a combustion space of about 1 to 20 cu. ft. per1,000 lbs. of coal per hour to" be gasified in generators H] or 2!!) is generally sufficient. Many modifications of the burner illustrated in Figure 3 may occur to those skilled in the art without deviating from the spirit of the invention.

While I have described above specific burner means suitable for the purposes of my process, the present invention is not limited to these specific means but is intended to include any means for completely burning finely divided carbonaceous solids of a high carbon concentration, say, above about 15 at temperatures above the fusion point of the ash.

Itshould also be understood that certain of the advantages of my invention will be realized when fixed or moving beds or dilute solids-in-gas sus- 1 1 pensions are used in my process instead of the fluidized beds described above.

My invention will be further illustrated by the following specific examples.

EXAMPLE I The continuous production of producer gas from bituminous coal using 95% oxygen and steam in a system of the type illustrated in Figure 1 of the drawing may be carried out at the conditions specified below.

Goal to fluid generator Pounds per hour 100,000

Temperature, F 60 Moisture, percent 1.5 Volatile matter, percent 33.0 Fixed carbon, percent 55.5 Ash, percent 10.0 Ash fusion temperature, F 2500 Fluid generator 10 Temperature, F 1800 Outlet superficial gas velocity, ft./sec 1.5 Fluidized solids, density, lbs./c. f 18 Fluidized solids, carbon concentration percent 40 E20 conversion, percent 80 Burner 40 Temperature, "F 3000 Solids from generator, lb./hr 16,600 Carbon concentration, wt. percent 40 95% O2 to burner, 1b./hr 77,500 95% O2 to burner, temperature, F 800 H2O to burner, lb./hr 74,000 H2O to burner, temperature, "F 1700 Fused ash discharged, lb./hr 10,000 Gases and vapors to generator:

CO2, percent 8.4 02, percent 27.0 N2, percent 1.9 H20, percent 62.7

Dry gas from generator 10 M. M. s. c. f./hr 4.07 Composition:

CO 56.9 Hz 30.6

100.0 B. t. u./c. f., net 194 EXAMPLE II For the continuous production of Water gas from bituminous coal using a two vessel system with an auxiliary burner as illustrated in Figure 2, the following conditions may be employed.

Coal to fluid generator 210 Pounds per hour 100,000

Temperature, "F 60 Moisture, per cent 1.5 Volatile matter, per cent 33.0 Fixed carbon, per cent 55.5 Ash, per cent 10.0 Ash fusion temperature, "F 2500 12 Fluid generator 210 Temperature, "F 1800 Outlet superficial gas velocity, ft./sec 1.5 Fluidized solids, density, lb./c. f 18 Fluidized solids, carbon concentration, per

cent 50 E20, temperature, "F 1700 H2O, conversion, per cent Solids to fluid heater 230, lb./hr 10,730,000

Solids from fluid heater 230, lb./hr 10,700,000

Dry gas from generator 210 M. M. s. c. f./hr 3.61 Composition:

CO 39.1 Hz 50.8 CO2 5.8 N2 1.0 CH4 3.3

100.0 B. t. u./c. f., net 296 Fluid heater 230 Temperature, "F 1900 Outlet superficial gas velocity, ft./sec 1.5 Fluidized solids, density, lb./c. f 18 Fluidized solids, carbon concentration, per

cent 50 002/00 ratio in outlet gas 4 Solids to burner, lb./hr 20,000

Burner 240 Temperature, "F 3000 Solids from fluid heater 230, lb./hr 20,000 Carbon concentration, weight per cent 50 Air to burner 240, lb./hr 336,000 Air to burner 240, temperature F 1400 Fused ash discharged, lb./hr 10,000 Gases to fluid heater 230:

The foregoing description and exemplary operations have served to illustrate specific applications and results of my invention. However, other modifications obvious to those skilled in the art are within the scope of my invention. Only such limitations should be imposed on the invention as are indicated in the appended claims.

I claim:

1. The process of converting solid carbonaceous fuels into gases containing carbon monoxide by an endothermic reaction with a gaseous gasifying medium conducted at an elevated conversion temperature in a conversion zone, which comprises contacting carbonaceous solids with a sulficient amount of said gasifying medium at a conversion temperature to convert a substantial proportion of the carbon of said fuels into said gases in said conversion zone, withdrawing product gas from said conversion zone, withdrawing solid carbonaceous gasification residue from said conversion zone, passing said withdrawn residue to a heating zone, subjecting said residue in said heating zone to a heat-generating incomplete combustion at a temperature substantially above said conversion temperature and below the fusion point of its ash, withdrawing flue gas from said heating zone, withdrawing carbonaceous heating zone residue from said heating zone, passing a portion of said heating zone residue to a combustion zone, subjecting said portion to combustion with a combustion-supporting gas in said combustion zone at a combustion temperature above the fusion point of the ash of said carbonaceous solids and at a ratio of combustionsupporting gas at least suflicient to burn completely the carbonaceous constituents of said portion subjected to said combustion, withdrawing liquid ash from said combustion zone, passing hot flue gases from said combustion zone substantially at the temperature of said combustion to said heating zone and passing another portion of said heating zone residue substantially at the temperature of said heating zone to said conversion zone to supply at least a portion of the heat required by said reaction.

2. The process of claim 1 in which sufiicient oxygen is supplied to said heating zone to favor the formation of 002 over that of C0.

3. The process of claim 1 in which a portion of the total oxygen supplied for said heating and combustion zones is fed to said heating zone and another portion to said combustion zone so as to supply sufficient oxygen to said heating zone to favor the formation of CO2 over that of CO in said heating zone.

4. The process of converting solid carbonaceous fuels into gases containing carbon monoxide by an endothermic reaction with a gaseous asifying medium conducted at an elevated conversion temperature in a conversion zone, which comprises contacting finely divided carbonaceous solids in the form of a dense turbulent mass fluidized by an upwardly flowing gas with a sufficient amount of said gasifying medium at a conversion temperature to convert a substantial proportion of the carbon of said fuels into said gases, withdrawing product gas upwardly from said mass, withdrawing finely divided solid carbonaceous gasification residue from said mass, passing said withdrawn residue to a heating zone, subjecting said residue in said heating zone to a heat-generating incomplete combustion in the form of a dense turbulent bed fluidized by an upwardly flowing gas at a temperature substantially above said conversion temperature and below the fusion point of its ash, withdrawing fiue'gas upwardly from said heating zone, withdrawing finely divided carbonaceous heating zone residue from said heating zone, passing a portion of said heating zone residue to a combustion zone, subjecting said portion to combustion with a combustion-supporting gas in a combustion zone at a combustion temperature above the fusion point of the ash of said carbonaceous solids and at a ratio of combustion-supporting gas at least suflicient to burn com letely the carbonaceous constituents of the portion of said residue subjected to said combustion, withdrawing liquid ash from said combustion zone, passing hot flue gases from said oombustion zone substantially at the temperature of said combustion to said heating zone to supply additional heat thereto and passing another portion of said heating zone residue substantially at the temperature of said heating zone to said conversion zone to supply at least a portion of the heat required by said reaction.

5. The process of claim 2 in which suflicien oxygen is supplied to said heating zone to favor the formation of CO2 over that of CO.

6. The process of claim 2 in which a portion of the total oxygen supplied for said heating and combustion zones is fed to said heating zone and another portion to said combustion zone so as to supply sufficient oxygen to said heating zone to favor the formation of 002 over that of CO in said heating-zone.

KARL J. NELSON.

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

UNITED STATES PATENTS Number Name Date 1,937,552 Davis, Jr. Dec. 5, 1933 1,984,380 Odell Dec. 18, 1934 2,113,774 Schmalfeldt Apr. 12, 1938 2,357,301 Bailey et al Sept. 5, 1944 2,436,938 Scharmann et a1. Mar. 18, 1948

Claims (1)

1. THE PROCESS OF CONVERTING SOLID CARBONACEOUS FUELS INTO GASES CONTAINING CARBON MONIXIDE BY AND ENDOTHERMIC REACTION WITH A GASEOUS GASIFYING MEDIUM CONDUCTED AT AN ELEVATED CONVERSION TEMPERATURE IN A CONVERSION ZONE, WHICH COMPRISES CONTACTING CARBONACEOUS SOLIDS WITH A SUFFICIENT AMOUNT OF SAID GASIFYING MEDIUM AT AT CONVERSION TEMPERATURE TO CONVERT A SUBSTANTIAL PROPORTION OF THE CARBON OF SAID FUELS INTO SAID GASES IN SAID CONVERSION ZONE, WITHDRAWING PRODUCT GAS FROM SAID CONVERSION ZONE, WITHDRAWING SOLID CARBONACEOUS GASIFICATION RESIDUE FROM SAID CONVERSION ZONE, PASSING SAID WITHDRAWN RESIDUE TO A HEATING ZONE, SUBJECTING SAID RESIDUE IN SAID HEATING ZONE AT A HEAT-GENERATING INCOMPLETE COMBUSTION AT A TEMPERATURE SUBSTANTIALLY ABOVE SAID CONVERSION TEMPERATURE AND BELOW THE FUSION POINT OF ITS ASH, WITHDRAWING FLUE GAS FROM SAID HEATING ZONE, WITHDRAWING CARBONACEOUS HEATING

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