US1952654A - Process of making blue and carbureted water gas - Google Patents

Description

March 27, 1934. H. J. CARSON 1,952,654

PROCESS OF MAKING BLUE AND CARBURETED WATER GAS Filed June 17, 1927 falls.

Patented Mar. 27, 1934 PATENT OFFICE PROCESS OF MAKING BLUE AND CAR- BURETED WATER GAS Hiram J. Carson, Cedar Rapids, Iowa Application June 17, 1927, Serial No. 199,572

11 Claims.

"This invention relates to improvements in method of producing water gas.

As is well known, in the usual operation of a water gas set, the time is roughly divided into two 7 periods: the air blasting or heating up period,

and the stream running or water gas making period. The heat developed during the blasting period, and stored in the generator fuel bed, is available in the gas making period for decompos- 1 ing the steam admitted to the generator.

In practice, at the begimiing of a running period, the decomposition of steam is rapid and nearly complete for a short period, but falls off rapidly thereafter, owing to the slower decom- 15 position as the generator fuel bed temperature It has been statedthat very little steam is decomposed at temperatures below 1000 deg. C. (1832 deg. F.) whereas the rate of decomposition is estimated to double with every rise of 100 deg. C. in temperature and such decomposition is very rapid at temperatures of 1200 deg. C. and above. Whfle the temperatures in the steam decomposition zone in a generator fuel bed may vary at different levels in that zone, it follows that the minimum practical temperature of its highest temperature portion is 1000 C. and the heat in the fuel bed useful for steam decomposition is the heat stored above that temperature.

In present operation insufficient account is taken of the foregoing facts. Steam admitted to the generator is actively decomposed at first,

but decomposition is soon arrested as the fuel temperature is lowered by the cooling action of such steamdecomposition. As the temperature drops, less and less of the steam admitted is decomposed, and this increasing excess of undecomposed steam hasthe harmful effect of further cooling the fuel bed with no useful result. To restore heat storage to the fuel bed at proper temperature levels after such cooling, fuel, air, and time are necessary, and as the fuel bed must be heated first to the temperature where steam decomposition begins at an'effective rate andas the useful heat storage is thatabove 1000 deg. C. the blasting and heating to bring the fuel bed temperature up to 1000 deg. C.-may be avoided'by keeping a minimum temperature in the steam decomposition zone of about 1000 deg. C. 5 In present practice, operation is continued until the accumulation of ash and clinker in the base of the generator prevents further operation in a practicable manner.' Gas making is then discontinued, to permit the removal of ash and clinker. after which operation is resumedn In present water gas practice air for blasting is supplied at low pressures and fan type air blowers are run only during the air blasting period.

One object of this invention is to provide an improved method or process of producing water gas in a water gas generating set and wherein the method or process is characterized by certain economies and efficiencies as compared with present practices.

Another object of this invention is to provide an improved method of manufacturing water gas wherein'is preferably employed preheated air for blasting, which is introduced uniformly to the fuel bed of a gas generator under sufficiently high pressure for the desired penetration thereof, and under control or regulation at different zones or levels to the end that a deeper bed of incandescent fuel may be created than has heretofore been economically attainable.

Another object of this invention is to provide a method of producing water gas wherein preferably superheated steam is employed during the gas-making period, the steam being also supplied to the fuel bed uniformly and under conso trol and in such manner as to prevent or minimize cooling of the bottom layer or zone of the fuel bed to thus permit ready ignition of the fuel at the beginning of a succeeding air blasting period. 35

Another object of this invention is to provide an improved method of producing water gas in a water gas generating set having a refractory bottom so that flux'ing materials may be introduced as required, and .the lower layer or zone of the fuel bed always maintained sufficiently hot that ash and clinker-forming materials may be drawn off in the form of liquid slag, to the end that the operation may be continuous or substantially continuous, and freed of the arduous labor and'loss of time occurring in water gas generating practices.

heretofore employed.

A more specific object of this invention is to provide an improved water gas generating method wherein the air blasting of the fuel bed is accomplished'by introducing the air, preferably pre-' heated, to the lower portions of the column of fuel, at vertically spaced or separated levels either simultaneously or successively and selectively, and the steam, preferably superheated, intro- 5 duced uniformly into the bed of fuel during the gas-making period, at a level above the lower most air blast level, whereby the temperature in the lowermost layer or zone of the fuel bed may be maintained to permit of the drawing of! of ash and clinker-forming material in the form of liquid slag.

Other objects of the invention are to provide certain improvements in method of generating water gas for conserving or utilizing heat which might otherwise be wasted; to effect certain economies in the carbureting of the gas and in certain other features incident to the production of blue or carbureted water gas in water gas sets having the usual or necessary auxiliary apparatus.

In the drawing forming a part of this specification, is illustrated more or less conventionally, partly in elevation'and partly in section, a carbureted water gas plant suitable for carrying out my improved method.

In the type of gas plant shown, four principal units are represented by the water gas generator 5, and adjacent carbureter 6, a gas superheater 7 and a steam superheater 8, the latter being shown with an air preheater 9 installed therein. A supplemental steam superheater 10 is shown connected to gas outlet 11 on the generator 5 which may be connected to gas outlet 12 when desired as shown by dotted lines.

A passageway 13 between the generator and carbureter is adapted to be opened and closed by a valve 14 (shown conventionally), and a similar passageway 15 between the superheaters 7 and 8 is supplied with a similar valve 16.

The generator is shown with a tapered and extended upper end with fuel supply opening 17 having a suitable closing gate or valve 18 and a suitable charging device 19 which has an outlet 122. Coal gas offtake 20 leads through regulating valve 21 to gas wash box or seal 22.

b As shown in the drawing and in order to carry out my improved method, the generator has omitted therefrom the usual bottom grate heretofore employed and instead the bottom of the generator is made as a closed hearth as 69, with an opening at 72 to allow for the outflow of the residual slag to which the ash is reduced by the high temperature of forced combustion. Another opening at 73 permits the introduction of a flux, both openings being normally sealed as by fire clay. Fluxing material such as limestone, soda ash, fiuorspar or iron ore may be introduced into the generator with the fuel as desired.

Pipes 23 and 23a supply oil to the checker brick chambers for gasification.

Air compressor or blower 24 supplies air for blasting through pipe 25, air receiver 26, pipe 27, valve 28, pressure regulating valve 29, pipe 30, valve 31, air preheater shown as coil 9, valve 32, and pipe 33, to the distributing headers of bustle pipes 34 and 35 through tuyere pipes 36 and 37 to the generator fuel bed and to the carbureter for secondary air through valve 55 and pipe 56, valve 57 being closed meanwhile. Valves 136 and 137 are shown in the tuyre pipes at each level 36 and 37 respectively and indicate one method of adjusting the flow at each level as desired. As will be obvious to those skilled in the art, one valve in the inlet to bustle pipe 34 and one valve in the inlet to bustle pipe 35 could be used to control the air supply to the bustle and tuyere pipes at the respective levels and thereby eliminate the necessity for a valve in each tuyre pipe.

The air blast gases pass from generator through passage 13, valve 14, down through carbureter 6,

through open connecting passage 41, up through gas superheater'l, stack valve 42 for stack 142 being closed, through valve 16 and passage 15 down through steam superheater 8 and up through passage 43 around air preheater 9, through which blasting air is simultaneously passing, and out to a stack 144 through stack valve 44.

Pipe 59 with relief valve 58 leads any excess exhaust steam to the atmosphere or to other steam using equipment, and prevents back pressure on the compressor rising beyond any predetermined point.

Valve 60, pipe 61, coil 62, steam trap 63 represent means for preheating air in receiver 26 with exhaust steam if desired and drawing 01f condensed steam through trap 63.

Pump 64, connected by pipe 65 to the base of gas superheater 7, with oil sprayed in to top of the gas superheater through supply pipe 230, as well as through pipe 23 into the carbureter, is used to draw oil gases out of the carbureter and superheater chambers, valves 14, 16 and stack valve 42 being closed and opening 12 closed off. By regulating the rate of pumping by pump 64 the desired conditionof reduced pressure for optimum conditions of oil gasification may be maintained in the carbureter and superheater, and the oil gases so formed may be delivered through pipe 66 to such farther point in the apparatus as is desired.

While the gasifying of oil is going on in these chambers, steam may be admitted to the top of the carbureter through valve 57 and pipe 56 and to the top of water gas superheater by opening valve 16 as desired and when oil is shut oif, steam so admitted may be used to purge these chambers of oil gases.

The course of the air blast gases through the apparatus has been described. The. potential heat in these gases is released through combustion with secondary air in the carbureter and tertiary air admitted to the checker brick steam superheater as desired and this released potential heat with the sensible heat in these gases is used to store heat in the carbureter, gas superheater, and checker brick steam superheater for asifying oil admitted to the carbureter and gas superheater during'the gas making period and, in the checker brick steam superheater, to superheat steam to the generator. The heat in the blast gases leaving the checker brick steam superheater is further utilized in preheating the air to the generator which is simultaneously passing through the air preheater shown as coil 9 before being discharged to the atmosphere through stack valve 44. The checker brick steam superheating and air preheating arrangement recover otherwise waste heat from the blast gases and return this recovered heat to the generator in the superheated steam and preheated air, thus effecting a substantial reduction in the amount of heat required from that stored in the generator fuel bed and in air and fuel consumed during blasting for a given amount of gas made. The use of the sensible heat in the newly made gas for giving the steam its initial superheat before entrance to the checker brick steam superheater permits a final higher degree of superheat, also a higher temperature of preheat in the air, as the blast gases pass through the air preheat ing chamber at higher temperatures because of the initial superheat in the steam and less cooling in the checker brick steam superheater.

During the gas making period, the superheated steam is delivered to the heated fuel bed in the generator through tuyere pipes 54 as previously described. The blue water gas resulting from the steam decomposition may all be taken through passage 13, carbureter 6, superheater '7, enriched'by oil simultaneously vaporized in the carbureter in the usual way and through offtake 12 and supplemental steam superheater 10, superheating the steam simultaneously passing through coil 49 and thence through regulating valve 67 to wash box 68, and thence through outlet 168 to such other apparatus as may be desired.-

It is, however, desired to use sensible heat in the newly made gas for passing through and carbonizing newly charged fuel such as bituminous coal in the upper portion of the generator. Accordingly a portion of the newly made blue water gas may pass through the carbureter and superheater, as above described, and the remaining portion pass upwardly through the newly charged fuel such as bituminous coal, and, mixed with coal gas, pass out through offtake 20. During the gas making period, with valves 14 and lfi-closed, opening 12 closed, and stack valve 42 closed, and oil sprayed in through oil supply pipes 23 and 23a, and oil gas pump 64 drawing oil oil gas, a portion or all of the gas newly made in the generator may pass through coal gas offtake 20 and any remaining portion may pass. through opening 11, valve 69 to superheating chamber 10, and.

thence to tar batter 68 as previously described.

Under such operation gas is drawn from three different points in the apparatus: coal gas and blue .water gas through offtake 20; blue gas through offtake 11; and oil gas through pump 64.

I The gases from the three points may be used separately or mixed later as desired but preferablyafter the coal gas drawn through offtake 20 has passed through necessary apparatus for recovering oils and byproducts usual with low temperature carbonization.

As coal gas will be given off from the newly charged coal inthe upper part of the generator .during both the air blasting andgas making periods, the regulating valve 21 in the coal gas oiftake is designed tovary the valve opening during these two periods so that during the blasting period, little or no blast gas is drawn off with the coal gas. I

The adjustment of regulating valve 21 and of similar valve 67 is so made that the desired fiow of gas is obtained through offtakes 20 and 11,

with oil pump 64 and oil spray pipe 23a used, or through oiftakes 20 and 12, if oil pump 64 and oil spray pipe 23a are not used.

In making uncarbureted water gas or blue gas, the carbureter 6 and gas superheater 7, and valve 14, may be dispensed with; and the passage 13 connected directly to valve 16, and passage 15 leading into checker brick steam superheater.

For making blue water gas the apparatus modified as above is used as in carbureted water gas practice During the gas making per'od, air may be ad-- mitted inrestricted amounts through the air tuyeres at the lowest level at any rate desired by adjusting the valves 13']. The combustion of such air generates heat in the generator while steam decomposition is go'ng on, and results in the formation of a limited amount of producer gas of a varying heating value, depending on the amount of air so introduced.

When non-volatile or low volatile fuel as coke or anthracite coal is used in the generator, all or part of the blue water gas may be drawn off through offtake 20 with ofitake 11 blanked off or ofi'take 20 may be blanked off and blue water gas drawn off through offtakes ll and passage 13 as desired.

With air supplied to the generator at two vertically spaced levels as at 36 and 3'7 and steam supplied at an intermediate level as at 54, the steam thus bypassing the underlying or lowermost layer of fuel, it is evident that such underlying fuel will remain at a relatively high temperature,

and the temperatures in the fuel opposite and just above the level of steam admission will be substantially lowered duringthe gas making pe- 'riod by the entering steam and the temperatures in the higher levels of generator fuel bed will be reduced less.

It is contemplated that steam will be admitted to the generator only so long as heat stored in the fuel bed is available above say about 1,000 deg. C. for steam decomposition.

During each air blasting period, the fuel just above the bottom surface will be of sufficiently high temperature, ll00 centigrade or more, formaintaining the ash and clinker-forming material in liquid form and w'll also be of slight depth. When the air is admitted at the lower level, it will, with the fuel, form carbon dioxide mostly and rapidly raise the temperature of the lower portion of the fuel bed. During the gas making period, the temperatures wll decrease toward the ash liquefying temperature and may possibly fall slightly therebelow. .Air admitted at the hgher level, will, with the fuel, form carbon dioxide mostly at first thus further raising temperatures and increasing the thickness of the high temperature zones in the lower portion of the fuel bed which thickness may be further increased by sim lar blasting at higher levels.

As the temperatures in fuel bed are raised above about 1,000 deg. C. throughout and the to the'desired point, all or any desired portion of the blasting air may then be admitted at the higher level. By this means the time of contact of air and blast gases wi"h the hot fuel will be reduced and by maintaining the air supply to fuel bed at the higher level in relatively large volume, optimumblasting or heat storing conditions will be attained and the greatest practicable portion of the carbon cogsumed from fuel will, with the air, form carbon ioxide, liberating the maximum amount of heat, raising the fuel bed temperature rapidly to the desired point so blasting may be discon'inuedv at this level and discontinued at higher levels when desired. In the manufacture of carbureted water gas and blue water gas, any carbon monoxide formed in Car the genera'or during air blasting may be burned to carbon dioxide by the further admission of air to the carbureter and/or checker brick steam superheater, and both sensible and potential heat in the blast gases leaving the generaior usefully 1 used to the most practicable extent for superheating steam and preheating air.

Conditions for the forming of carbon, monoxide during the air blasting period are most favorable at the end of the air blasting period. Should heat during the blasting period be required in the upper portion of the generator for carbonizing coal, optimum conditions for the production of carbon monoxide may be maintained during the latter portion of this period and the blast gas or producer gas so formed drawn off with coal gas simultaneously produced, through the coal gas oiftake.

It is well known that the preheating of air for combustion makes possible increased temperatures from such combustion and combustion is more nearly complete. This increases the efiiciency and makes higher combustion rates possible. Particularly is this true in a water gas generator where the heat for decomposition of the steam is supplied at relatively hightemperature levels.

The relatively large volumes of air at low pressure now used in current gas making practice and the intermittent nature of the operation, together with the large piping necessary for transmitting air at low pressures has made it difficult if not impracticable to preheat air because of,

the bulky and expensive equipment required.

The use of air at sufiiciently high pressures for the desired. penetration of the generator fuel bed, permits a reduction in the size and cost of the piping, valves and insulation required.

When the air is first compressed to relatively high pressures, the large air receiver permits relatively continuous operation so that part or all of its exhaust steam is available for gas making.

It is evident that, by superheating the steam for introduction to the generator, less heat will be required from the heat storage in the generator fuel bed for its decomposition and more nearly optimum conditions for the production of blue water gas and complete steam decomposition will be so obtained.

It is also evident that with a solid bottom in the generator and means'for drawing off the ash and foreign matter in the form of molten or liquid slag, the present limitations on temperatures in water gas generators are largely removed and a more nearly clean fuel bed with a' consequent more uniform porosity of the fuel bed maintained.

The use of relatively small tuyere pipes spaced circumferentially around the generator for air and steam admission to the generator fuel bed, insures a uniform distribution of each to the different parts of the fuel bed.

In carbonization of coal, it is well known that coal gas given off at low temperatures has a high heating value and may be processed for the recovery of valuable by-productsw Low temperature conditions are obtained in the carbonization zone in the upper portion of the generator described and a high heating value gas which, after processing for by-products, may be mixed with blue water gas and thus decrease the need for enrichment -by oil gases.

The maintenance of reduced pressures in the carbureter and gas superheater independently of generator pressures during the oil gasifying period provides nearly, optimum conditions for the production of stable oil gases, and pressures and velocities in the generator may be suited to optimum conditions'for the production of gas in the generator.

Under conditions favoring the alternate admissi'on of air and the steam at one level, the air supply is connected to steam header or bustle by a pipe '70 and valve'71.

In the preceding description, I have set forth considerably in detail the manner in which. my improved method or process will preferably be carried out in connection with the type of apparatus illustrated in the drawing, but the same is by way of illustration only and all changes and variations are contemplated that come within the scope of the appended claims.

Having thus described my invention, I claim:

'1. An improvement in the method of manufacturing water gas, consisting in progressively air blasting a generator fuel bed to incandescence at vertically spaced levels in successive zones with the lowermost air blast level in the bottom zone of said fuel bed, and, mainly alternately, admitting steam to the fuel bed above the lowermost air blast level, introducing fluxing material in bottom zone of said fuel bed, and discharging ash and clinker forming material as liquid slag.

2. A process for the manufacture of carbureted water gas, which consists in blasting a fuel bed having a lower incandescent zone and an upper coal distillation zone with preheated air substantially progressively at vertically spaced levels separately controllable at each level in substantially successive zones, with the lowermost air blast level in the bottom zone of the said fuel bed, the air blast gases thereby produced being caused to pass successively through a carbureting chamber and a regenerator, being burnt therein, and through a recuperative type of air preheater, thereby heating the air for blasting simultaneously passing through the said recuperator, and, mainly alternately, blowing steam through the regenerator being superheated therein, to the incandescent fuel bed at a level above the lowermost air blast level and below the uppermost air blast level, causing a portion of the hot water gas thereby produced to pass through the coal distillation zone, drawing off the coal gas thereby produced with the admixed water gas, causing the remaining portion of the water gas to pass through the carbureting chamber, in which a liquid hydrocarbon is simultaneously introduced, drawing off the hydrocarbon gases thereby produced with the admixed water gas, and discharging the ash and clinker forming material from the fuel bed as liquid slag.

3. An improvement in the method of manufacturing water gas, consisting in air blasting a fuel bed in a generator to incandescenceat vertically spaced levels with the lowermost air blast level in the bottom zone of the fuel bed, and, alternately, generating water gas by admitting steam to the fuel bed above the lowermost air blast level and below the uppermost air blast level and causing the steam so admitted to pass upwardly through incandescent fuel at higher levels, and discharging ash and clinker forming material from the fuel bed as liquid slag.

4. The herein described process of manufacturing water gas which includes: introducing-air blasts at vertically spaced levels into a column of fuel, one of said air blast levels being in the bottom zone of the fuel column; alternately with said air blasting introducing steam into said fuel column only above said lowermost air blast level; passing substantially all of the blast gases from the upper portion of the fuel column into a regenerative chamber and supplying additional air to complete combustion; said steam, before admission to the fuel column, being passed through the regenerative chamber and thereby highly superheated; and drawing off ash and clinkerforming material as liquid slag.

5. The herein described method of manufacturing water gas which includes: progressively air blasting a fuel bed in a generator to incandescence at vertically spaced levels in successive zones with the lowermost air blast level in the bottom zone of said fuel bed; alternately with said air blasting, generating water gas by admitting steam to-the fuel bed in the lower portion thereof only above the lowermost air blast level; and discharging ash and clinker-forming material from the fuel bed as liquid slag.

6. The herein described method of manufacturing water gas which includes: air blasting a fuel bed in a generator to incandescence at vertically spaced levels with the lowermost air blast level in the bottom zone of said fuel bed; and, alternately with said air blasting, generating water gas by admitting steam to the fuel bed in the lower portion thereof only above the lowermost air blast level, whereby the bottom zone of' the fuel bed is continuously maintained at a 7 high temperature and ash and clinker-forming material from the fuel bed is dischargeable as liquid slag.

7. The herein described method of manufacturing water gas which includes: blasting with air a fuel bed in a generator to incandescence at vertically spaced levels with the lowermost air blast level in the bottom zone of said fuel bed; alternately with said air blasting, generating water gas by admitting steam to the fuel bed in the lower portion thereof only abovethe lowermost air blast level; and, during the steam admission period, admitting a controlled and restricted amount of air at the lowermost air blast level whereby to maintain the bottom zone of the fuel bed continuously at a high temperature cause ash and clinker-forming material from the fuel bed to be discharged as liquid slag.

8. The herein described method of manufacturing watergas which includes: blasting, at vertically separated levels and under selectivecontrol at each level, a column of fuel in a generator to incandescence with air, the lowermost level of air blasts being introduced in the bottom zone of the fuel column; alternately with said air blasting, generating water gas by admitting steam to the fuel column only above said lowermost air blasting level and causing said steam to travel lengthwise of the fuel column; and drawing off ash and clinker-forming material from thefuel column as liquid slag.

9. The herein described method of manufacturing water gas which includes: blasting, at vertically separated levels, a column of fuel in a generator to incandescence with air, the lowermost level of air blast being introduced substantially at the bottom of the column of fuel; always main-'v taining the bottom layer of the fuel column at least as high as the ignition temperature of the fuel and substantially as high as temperature for liquefaction of the ash and the clinker-forming material; and, alternately with said air blasting, introducing steam for generating water gas into the fuel column only above said bottom layer, and causing the water gas formed therefrom topass upwardly of the column.

10. The herein described method of 'manufacturing water gas which includes: blasting a column of fuel in'a generator to incandescence with air introduced at relatively high velocity substantially at the bottom of the column and at a vertically spaced level above the bottom, said blasting being selectively controlled at each level; and, alternately with said air blasting, introducing steam under relatively high velocity to the column at a level intermediate said top and bot tom air blast levels, and generating gas by causing the steam to travel vertically upwardly of the column from the level where introduced, whereby the bottom portion of the column may be maintained always above the ignition temperature of the fuel; and drawing off ash and clinker-forming material from the fuel column as liquid slag.

11. The herein described method of manufacturing water gas which includes: providing a vertical column of fuel; blasting the lower zone of said column with preheated air introduced substantially transversely of the column at vertically separated levels and causing the air and resultant products to then pass vertically upward of the column; alternately with said air blasting, in-

troducing superheated steam substantially transversely into the column of fuel only at a level vertically spaced above the lowermost air blast level,

drawing off ash and clinker-forming material from the fuel column as liquid slag.

12. The herein described method of manufacturing water gas which includes: periodically air blasting a fuel bed in a generator to incandescence with the air blast levelin the bottom zone of said fuel bed; periodically and alternately with said air blasting, generating- Water gas by admitting steam to the fuel bed in the lower portion thereof only and at an appreciable distance above the air blast level; and discharging ash and clinkerforming material from the fuel bed as liquid slag.

13. The herein described method of manufacturing water gas which includes: air blasting the fuel bed in a generator to incandescence with the air blast level in the bottom zone of said fuel bed; alternately with said air blasting, generating water gas by admitting steam to the fuel bed in the lower portion thereof only above the air blast 1 level and, while so admitting the steam, admitting a controlled and restricted amount of air at said air blast level in the bottom zone of the fuel bed whereby to maintain the bottom zone of the 'fuel bed continuously at a high temperature; and

discharging ash and clinker-forming material from the fuel bed as liquid slag.

14. The herein described method of manufacturing water gas which includes: blasting, at vering the steam therein and passing the superheated steam to the incandescent fuel at a level above said lowermostair blast level; causing the hot water gas thereby produced to pass through the coal and drawing off the coal gas therebydistilled by the sensible heat in the water gas, admixed with the water gas; and discharging ash and clinker-forming material from the bottom zone of the column as liquid slag 15. The herein describedimprovement in the method of manufacturing water gas from a column of fuel in a'generator and wherein the column of fuel has a lower generating zone and an upper distillation zone, which includes: blasting the fuel to incandescence with air in said lower generating zone by introducing the air into said lower generating zone being in the bottom the fuel at vertically spaced levels and at a plurality of points around the periphery of the fuel column at each level, the lowermost air blast level zone and above the bottom surface thereof; selectively controlling the admission of air at each level; drawing off the air blast gases from the upper portion of said generating zone; and, alternately with the air blasting period, generating water gas by admitting steam into the fuel in at a plurality of points around the periphery thereof and at a level above said lowermost air blast level, the steam so admitted being caused to pass upwardly through incandescent fuel at higher levels within said lower generating zone and the hot water gas thereby generated being caused to pass through said upper distillation zone to distill the fuel therein, said air blasting and steam admission steps being employed during each cycle of operation; and drawin off the distillation products admixed with the water gas from the upper portion of said upper distillation zone.

16. A process of manufacturing water gas which portion of said generating below the top thereof upward through the lower part of the fuel column.

17. A process of manufacturing water gas which includes the following steps: air blasting to incandescence the lower portion of a column of solid fuel, leaving the upper portion consisting of fresh fuel, the air being introduced to the bottom of the fuel column and to a point above the bottom of the fuel column and passed upward through the lower portion of the fuel column; and another step being introducing all the uprun steam for the process at the point at which the portion of the air is introduced above the bottom of the fuel column, and passing the steam upward through thelower part of the fuel column.

HIRAM J. CARSON.

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