US2094946A - High pressure gas making process - Google Patents

Description

Oct. 5, 1937. o. HUBMANN, 2,094

HIGH PRESSURE GAS MfxKIfiG PROCESS Filed Feb. 27, 1931 2 Sheets-Sheet 1 Oct. 5, 1937. o, UBMANN 2,094,946

HIGH PRESSURE GAS MAKING PROCESS Filed Feb. 27, 1931 2 Sheets-Sheet 2 I a I r I I I I i Gas 1 j-I Pur fzor 1 H 0, C0,

1 S- Cnmrou Z I 5 I 3 I I I 4 I lnvenfor:

Patented Oct. 5, 1937 UNITED STATES men PRESSURE GAS MAKING raocass Otto Hubmann,

Frankfort-on-the-Main,

Ger-

many, assignor to American Lurgl Corporation, New York, N. Y., a corporation of N York Application February 27, 1931, Serial No. 518,834

I In Germany March 10, 1930 14 Claims.

This invention relates to a process for the production of gas of high calorific power, and byproducts, by gasification with oxygen under elevated pressure.

For the production of a high-power gasthat is to say, a gas of higher calorific power than ordinary producer gas-it has recently been proposed to effect the gasification by means of oxygen, followed by improving the crude gas by efiecting catalytic formation of hydrocarbons and washing out the inert carbon dioxide. For remote supply, this gas must be compressed to the requisite pressure after purification to remove sulphuretted hydrogen and the like, unless such compression has been effected prior to the improving treatment. The production of high-power gas in this manner, however, is attended with technical and economic difficulties which are mainly attributable to the existing inadequate output capacity of the proposed apparatus and processes, the cost of the necessary oxygen, the expense of compressing large volumes of gas, and the difliculty of controlling the temperature conditions in the bed of fuel, so that, up to the present, nothing is known with regard to the carrying out of these proposals on a technical scale.

In order to obviate these difiiculties, the process of the present invention gasifies the fuel with oxygen, or air enriched with oxygen, and abundant quantities of steam, under elevated pressure. In special cases carbon dioxide may be added to the oxygen, in addition to, or instead of, steam.-

Types of gas producers, designated high-pressure producers, are known, but, unlike the invention, these do not work with a pressure of several atmospheres. On the contrary, they serve for the gasification of small coal with blast pressures up to about 700 mm. water-gauge. The positive pressure is mainly applied for the purpose of penetrating through the column of coal in the producer, and the resulting gas is of the ordinary pressure. Although recent proposals refer to the pressure gasification of semi-coke with steam, this process is attended with difiiculties which cannot be overcome by the means at present available in the art, since it is essential, for the continuous performance of the endothermic water-gas reaction, to supply heat, the provision of which, by superheating thehigh-pressure invention. On the other hand, in all the existing steam to temperatures exceeding 600 C. is technically impracticable.

It has also been proposed to perform the gasification process, at the highest practicable temperatures, with dry air, or air with the smallest possible addition of steam, as gasifying agent, and under such increased pressure that the influence of pressure and high temperature produces extensive cracking of the tar contained in the fuel, and converts it into gaseous hydrocarbons. By this means, the calorific power of the gas is slightly increased and the formation of condensable constituents, such as tar, oil, and the like, prevented.

For remote or urban gas supply, however, the 15 latter process cannot be considered, since'neither the calorific power nor the composition of the gas, nor, in particular, its specific gravity, or content of hydrogen and carbon monoxide, .are suflicient for these purposes.

On the other hand, a gas of very high-grade quality and rich in methane and hydrogen is obtained by gasification, under elevated pressure, with oxygen, or air enriched with oxygen, and a copious addition of steam, in accordance with the present invention. The process of the invention operates, for example, in the following manner:

The gasifying medium admitted into the producer consists of oxygen under pressure, to which, according to the invention and contrary to the usual practice, steam is added in such quantities as thereby to lower the reaction temperature in such a manner that, apart from the production of a gas which is, above everything, low in carbon monoxide, the difiiculties with regard to the structural material of the gasification shaft and the clinkering of the gasification residue are entirely obviated. Moreover, the said steam can be supplied at a superheat of about 450 C., which is easily attained in practice. The admission pressure of the gasifying medium can be sufficiently high to obviate the necessity forcompressing the resulting gas any further for the purpose of remote supply and purification (such as washing out the carbon \-dioxide). No compression is needed, both the steam and oxygen required for the gasiflcation being obtainable, without any considerably increased expense, under the pressure at which they are employed according to the requisite degree. Economical gasification with given grain-size of fuel, the production of dust oxygen has, for the first time, been rendered I possible by the economy which the new process effects by dispensing with compression.

The reaction under high pressure has a further advantageous effect in that it is attended with a substantial increase in the throughput. For a and the risk of local eruptions of gas in the producer is known to be proportional to the square of the velocity, and directly proportional to the specific gravity of the gasifying agent, and therefore with increasing gasiflcation pressure, (in contrast to the usual gasiflcation under approximately atmospheric pressure), the cross- -sectional load can also be increased in proportion with the square root of said pressure, so that-quite irrespective of the increased output already rendered possible through gasiflcation with oxygen-the throughput of fuelcan also be increased, for example by about 3.8-fold in the case of gasiflcation under a pressure of 15 atmospheres.

In the process of the present invention, the application of high pressure in conjunction with an increased proportion of steam, also produces a considerable improvement in the high-power gas, through the formation of hydrocarbon compounds (CHaCzHa and the'like), as the result of the hydrogenating action of the resulting hydrogen on the fuel. With regard to the general course of the gas reaction, it is known that rising temperatures facilitate the decomposition of compounds of high molecular weight in the direction of the hydrogen side of the reaction equation. Increased pressure, on the other hand, leads tothe system with small volume, that is to say, in this case, to the formation of hydrocarbon compounds by hydrogenation with the free hydrogen. Experiment has demonstrated that it is possible-especially in the case of geologically more recentfuels like peat and lignite-by operating in this manner, to carry out a continuous gasification process at temperatures of 600- 700 C., so that low temperatures and high pressure already influence the course of the reaction in the gas producer in the direction of the formation of the desired hydrocarbons. Moreover, the reaction may be substantially accelerated by adding catalytically active substances to the fuel. A particularly advantageous feature, however, is that the formation of carbon monoxide is lessened, by the low gasiflcation temperature and the effect of the high pressure, in favour of the formation of carbon dioxide, so that the final gas contains considerably less carbon monoxide than other gases produced by gasiflcation, for instance, normal water gas, while the inert carbon dioxide can be easily removed by the aid of known methods. This is the more feasible inasmuch as the gas blown in accordance with the presentinvention is produced with the pressure needed for the process of eliminating carbon dioxide, and the compression otherwise required is therefore superfluous. At the same time, the amount of oxygen needed per cubic metre of gas produced, decreases as the pressure increases. 1

with the process as described it is possible amass of the calories contained in the fuel into a gas of. more than 565 B. t. u. per cubic foot. Working under a pressure of 25 atmospheres anthracite coal with 8% volatiles has been completely gasifled in continuous operation to a gas of the following composition:

and corresponds to coal gas in point of density, fglorific power and low content of carbon monox- The gas furnished by the process of the present invention can be subjected direct to any convenient additional processes forv purification and improvement, the performance of which processes is substantially facilitated and accelerated by the pressure already existing. This applies, in general, as regards the elimination of condensable or gaseous constituents, whether by compression followed by supercooling, or by adsorption or chemical combination with the aid of solid or liquid substances, and also as regards the performance of reactions in which conversions are effected by catalytic action. By gasification under elevated pressure, the present process enables even inferior fuels-such as brown-coal-to be converted into a high-power gas corresponding to coal gas in point of density, calorific power and low content of carbon monoxide.

Pulverulent fuels can be treated, with special advantage, by the process of the present invention. The employment of dusty and fine-grain fuels considerably facilitates the introduction of the charge into the reaction chamber which is under pressure, and also the removal of the residues, which remain in a pulverulent condition owing to the low gasification temperature of the process. Naturally, in such case the gasifying reaction does not take place in a stationary bed of fuel, the fuel dust being, on the contrary, fed towards the ascending reaction gas in known manner, and preferably in a state of agitation.

In such event, the process according to the present invention is carried out, for example, in that the dust to be gasified is allowed to trickle down through (for example) a brick-lined vertical or inclined shaft, whilst the gasifying medium is introduced, under high pressure, at the bottom of the shaft, and ascends to meet the dust. In this manner, the dust is kept in a state of suspension-for example by introducing the gasify ing medium tangentially-for some time, in known manner, and converted into gas.

Another embodiment of the invention consists in introducing the gasifying medium and dust, in the same direction, into the bottom of the reaction apparatus, the upper portion of which, however, is conically widened, so that, through the reduced velocity of the gas, the dust is, at

least partially, separated from the current of gas.

In this case, the gasification residue can be removed by interrupting the admission of the gasifying medium for a few seconds, at intervals of (for example) 5 minutes, so that the residue canfall down through the narrow zone. Under these conditions there is no need to reduce the pressure in the gasiiication chamber.

In order to increase the hydrogenating action of the hydrogen formed in the gasification process, a hydrogenation zone may be disposed in front of the gasification zone, so as to enable the liberated hydrogen to act for some time on the fuel before the latter is gasified. The gases containing the hydrogen can pass directly from the gasification zone into the superimposed hydrogenation zone, while the fuel gradually sinks down through the gasification zone. The heat necessary for hydrogenation is furnished,

.for the most part, by the ascending gas itself.

However, since the hydrogenation reaction is greatly accelerated by accurately regulating its temperature, the hydrogenation zone can be specially provided with additional heat, for example, in known manner, by radiators traversing the hydrogenation zone and heated either by gas or by electrical heating resistances. In the case of suitable fuels, the fuel itself may also act as the resistance for the electric current, and thus serve as a heating agent. The fuel itself is preferably raised to the high temperature required for the time being, before it enters the hydrogena tion zone.

The pressure under which the gasificat ion proceeds need not, of course, correspond to that in the distribution mains. Thus, in some cases, it may be preferable to gasify under a higher pressure, if this enables a high-power gas to be produced which will have the desired composition after the carbon dioxide has been washed out. The surplus pressure energy can then be utilized, to advantage, for driving the auxiliary machines required for carrying out the process. Conversely-taking the process, as a whole, into consideration-the pressure in the gas producer may be kept somewhat lower than is needed for the fur- The arrangements for charging and emptying a gas producer operating in accordance with the process of the present invention must, naturally, be designed in'accordance with special points of, view. In the existing methods of gasification under ordinary pressure, the gas producer was mostly provided with a double seal hopper through which the fuel was introduced into the gasification chamber. In gasifying fuelsunder pressure, however, the sealing appliances have, in contrast to all those hitherto known, to be maintained gas-tight against an extremely high pressure and are subjected to heavy wear. When they are being opened, the pressure balance between the several chambers occurs with a very rapid flow of gas, and the fuel carried in the gas current abrades the jointing surfaces, in particular, very extensively. Moreover, it is essential that losses of gas while charging should be prevented as far as is possible.

According to the present invention, these difficulties are obviated by the provision of a charging look, into which the fuel is introduced, the chamber being then closed and the internal pressure raised to that of the gasiflcation chamber by means of the surplus carbon dioxide from the process itself, and/or by steam, or similar means. The fuel is then transferred from the lock to the gasifier, and communication between the lock and gasifler-is again interrupted, for the purpose of introducing a fresh charge. For very moist fuels, the charging lock can also be designed in such a manner that the fuel can be dried therein, in known manner, by the direct introduction of high-pressure steam. Similarly, the discharge of the gasification residue can be effected with the aid of a lock, or by flushing. Thegas producer itself is designed, in the usual manner, as a lined cylindrical shaft, with or without mechanical ash-handling appliances, and, notwithstanding the high pressure, is of relatively large cross section, since, owing to the lower gasification temperatures employed, the stresses to which the shell of the producer is exposed, can be kept within technically controllable limits. Moreover, the shell can, without difliculty, be cooled bywater or air.

The gas producer may also be charged by forcing the coal in, through a suitably tapered mouldq ing channel, under a considerably higher pressure than that of the gasiflcation chamber, in such a manner that the fuel pressed into said channel forms a seal between the internal pressure 'of the producer and that of the outside air.

For example, a brown-coal briquetting press (not shown) of known type may be used. The gas-tight moulding channel of this press terminates in a section of pipe corresponding with the shape of the briquette and discharging into the high-pressure gas producer. The crumbly or finegrained coal is placed in the charging hopper of the briquette press and forced by the press ram into the moulding channel. The bends in the channel are gradually tapered so as to set up a high frictional resistance, sufficient to produce blocks of adequate tenacity and enable the plugs thus formed to stand the internal pressure. The charging hopper of the press is preferably closed by a self-acting lock, operating under a low (approximately atmospheric) pressure, to protect the operators against any gas that maypossibly issue through the moulding channel of the press. Moreover, the gases are preferably evacuated from the charging hopper, so as to prevent them from inconveniencing the operators in any circumstances.

For gas-producer plants comprising a plurality of producers, it has also been recognized as particularly advantageous for the charging and ash removal of the several producers to be effected through lock appliances common to all, and the charge introduced into each only after being locked in the pressure chamber. In addi tion to reducing the expenditure in material and manual labour, this method obviates, in a practically complete manner, the possibility of the process being jeopardized through faulty attention and through leakage at the seals. In certain cases it is also advisable to employ lock chambers of greater capacity than usual and capable, for example, of containing sufficient fuel for a pro longed working period. Moreover, two (for example) of these larger charging appliances may be provided, which are placed in communication, at intervals, with the pressure chambers of the gas producers, preferably by means of an interposed special conveyor device, such as a worm (not shown) which distributes the fuel to the various points of utilization Naturally, in this case also, the fuel can be introduced into the distributing chamber for the various producers by means of a press instead of a lock.

In order more clearly to understand the invention, reference is made to the accompanying drawings which illustrate diagrammatically and by way of example typical forms of apparatus for carrying out the process, according to the invention.

Fig. 1 is a representation of several gas producers, combined into a plant with common charging and residue-handling appliances.

Fig. 2 represents an apparatus suitable for hydrogenation at the same time.

The gas producers l, 2 and 3 have a common charging appliance, consisting of the lock chamber 4, adapted to be hermetically closed at the top by a cover 5. The lock chamber houses the (also gas-tight) seal 6, consisting of a cone Ba, which is adapted to be raised and lowered by means of rods 6b and counterweight 6c, and is pressed in a gas-tight manner against the seating surface of the interior member 6d directly the pressure in the lower portion of the lock chamber exceeds that in the upper portion. Charging pipes l4 lead .from the bottom of the lock chamber to the several producers. These pipes l4 may be provided with valves (not shown) serving to regulate the distribution of the coal to the several producers in the desired manner. The pipe l0 leads from one of the supply pipes H, or from a producer, into the upper portion of the lock chamber, from which latter, gas can be led away through the exhaust pipe I I. The pipes l0 and II are provided with stop-valves 10a, or i la. The gas producers, which consists of a shell of strong material, such as steel, and a lining H of refractory material, are supplied with the gasifying agent through the'pipes l2, and the gas produced is led away through the pipes I3. I8 are the discharge openings from the producers, and are succeeded by conveyor devices, such as worms 1, which transport the gasification residues into the pipes l9 leading to the discharging apparatus, which is arranged in the same manner as the charging device. It consists of a lock chamber I5, which is closed below by the gastight cover 9, and is divided into an upper and a lower chamber by a member 8, which also closes in a gas-tight manner. The member} may be \designed in the same way as the member 6 of the charging device, that is to say, may consist of a cone 8a, fitting gas-tight into the member 8d and being raised and lowered by means of rods 81) and counterweight 8c. The gas-tight seal between the surface of the cone and the seating surface of the member 8d must, howeverin'this case, be effected under a correspondingly high pressure, produced, for example, by hydraulic means. A gas pipe 20 connects the lower portion of the lock chamber 8 with the producer, or the discharge pipe l9, whilst another pipe 2| serves to lead the gas out of the lower chamber of the lock. Both pipes are fitted with stop-valves 20a and 2 la.

For the purpose of admitting the fuel into the lock 6, the gas in the upper portion of the lock chamber is first evacuated through the pipe ll, until the pressure in the upper portion of said chamber is approximately atmospheric. The upper portion of the chamber will then become shut off, gas-tight, from the lower portion by the cone in 'and the member 6d, whereupon the cover I is opened and fuel is admitted into the upper portion of the lock chamber. After this portion has been reclosed by the cover 5, the valve 10a in the gas pipe 10 is opened and the upper portion of is recharged with fuel.

the lock chamber is exposed to the pressure which obtains in the gas producers. The cone'lia may now be lowered, so that the fuel drops out of the upper portion of the chamber into the lower, from which it is distributed to the several producers by way of the pipes H, and is gasified.

The gasification is effected by admitting a mixture of oxygen and steam through the supply pipe II, the free space existing below the shoulder 22 on the lining assuring better distribution of the gasifying medium in the producer.

The gasiiylng medium, which may consist, for

example, of 1 part byvolume of oxygen to 6-l0 parts by volume of steam, is introduced under a pressure of about 20-50 atmospheres. The resulting gas, which issues from .the producers through the pipe 13, is under approximately the same pressure. The gasiflcation residues pass from the discharge openings l8, through the worms I andinto the upper portion of the lock chamber 15, where they accumulate above the cone. If the lock chamber has become sufficiently full, the cone is lowered so that the residues drop into the lower portion of the chamber. After the cone 8a has been lifted and a gas-tight seal has been established between the lower and upper portions of the lock chamber, the pressure in the lower portion is relieved, the cover 9 is opened, and the residues in the said lower portion are discharged. After the lower portion of the lock chamber has been reclosed and placed under sufficient pressure by admitting gas through the pipe '20, a further batch of gasiflcation residues can be discharged in the same manner. Hence, by means of this, or some analogous design of the charging and discharging apparatus, the gasification can be performed in a continuous manner without any working difliculties, and, inasmuch as the same charging and discharging apparatus can be employed for a series of producers, th operation is also comparatively simple.

If, inspecial cases, very high pressures are to be employed, intermittent gasification may be preferred to this continuous operation. Forthis purpose, the pressure in the gasiiication chamber is relieved when the reaction has termihated, the residue is evacuated, and the chamber Under these conditions, the provision of special locks may be omitted.

If the gasification is to be accompanied by the hydrogenating action of the hydrogen, or the like, contained in the resulting gases, on the fuel from which the volatile constituents or a large portion of the same have been removed by heating, if at all, the apparatus according to Fig. 2 may be employed with advantage. This consists of a (for example) cylindrical steel shaft a, which must be constructed to stand an internal pressure, such as atmospheres (according to circumstances). This steel cylinder is lined with refractory and :insulating material, and its interior space is divided, from above downwards,

into a hydrogenation zone b, a gasification zone 0, and an ashpit d. On top of the steel cylinder is a charging device e for the admission of the fuel. The ashpit d'isprovided with a discharge outlet f. The charging and discharging apparatus may dioxide, below the gasification zone 0, by way of the supply pipe h. The gaseous products of gasification are led away from the top of the hydrogenation zone b, by way of the pipe 2', in order to be subjected to further treatment, such as the removal ofwater vapour, carbon dioxide, condensable hydrocarbons and sulphur compounds. The purified gas is then directly available, under pressure and with a calorific value suitable for urban gas purposes. It may, of course, also be subjected to further transformations, or rendered suitable for chemical purposes, such as ammonia synthesis, or the like. For example, in producing the oxygen needed for the process by compressing air, the nitrogen obtained in that operation may, with particular advantage, be utilized, in association with a portion of the gas from the producer, for the synthetic production of fertilizers.

In order to increase the hydrogenating action, the gas (or a portion of same) produced in the gasification zone may also be led off through the pipe is, between the gasification and hydrogenation zones, and freed, in the first place, from steam, carbon dioxide and sulphur compounds. This purified gas, after being heated to hydrogenation temperature, may be passed, through the pipe 2' into the hydrogenation zone. In such case, the hydrogenation products can then be. removed from the hydrogenation zone by way of a separate pipe, or else, in association with the gases from the gasification zone, through the pipe is. Under these conditions a circulation of part of the gases containing hydrogen, is set up through the hydrogenation zone I) and the apparatus for the separation of the hydrogenation products,

carbon dioxide and sulphur-hydrogen compounds. Nevertheless, the gas from the'gasification zone 0 and the gas from the hydrogenation zone b may be separately withdrawn from the producer and separately purified.

In the same manner as for the generation of the gas, the hydrogenation reactions may be accelerated by the addition of catalysts or accelerative agents, such as compounds of alkalis, calcium or iron, to the fuel. Particular advantage attaches to the employment of such additions as volatilize at the higher temperatures in the gasification zone and, in an extremely divided condition, are returned, as mist, into the hydrogenation zone, by the resulting gases.

In some cases it is also of advantage to introduce into the hydrogenation zone by-products,

phenolates and like substances, from the process itself or from external sources, which can thus be converted into light oils and valuable gases .without any additional cost.

The gas produced by the process of the present invention, isalready under a high pressure, such as 20 atmospheres, and therefore the steam contained therein condenses, during the cooling and purification of the gas, at a considerably higher temperature than heretofore. Surface or injection condensers may be employed. A steam of medium pressure, which may, for example, be compressed to the gasification pressure and returned to the gas producer, may be suitably generated from the condensate.

If the gas produced in accordance with the invention is to be employed for ammonia synthesis or hydrogenation purposes, it is advantageous to operate so that it will contain as high a proportion of hydrogen as possible. According to the invention, this result is achieved in that, by means of a relativelyshortreactionperiod between the gasifying medium and the fuel, (rapid passage of the gasifying medium through the fuel), the reduction of the carbon dioxide to carbon monoxide is still further restricted, and the combination of the hydrogen and carbon, to, form hydrocarbons, is kept down as far as possible. 5 In this manner, a gas consisting of hydrogen and carbon dioxide, to the extent of about 80% can be obtained.

The composition of the gas can, of course, also be influenced, in a desired and already known manner, by incomplete gasification of the fuel, or also by partial removal of the degasified fuel. In the gasification of bituminous fuels, .9. dry distillation with resulting formation of gas and condensable hydrocarbons takes place intheupper portion of the gas producer, even when no special hydrogenation zone is provided. A coke-like fuel passes into the gasification zone proper. It is not necessarilyto gasifyall of thisfuel. A portionof it mayberemoved from theproducer beforethe gasification, or the gasification may be so conducted that some carbon is still present in the residue. It is thus possible to raise the content in distillation gases of the final product and consequently, also, to increase the calorific value of the gas.

'In gasification with oxygen under ordinary pressure, it has hitherto been the practice to separate the oxygen from air by known processes. In such case the oxygen is obtained under ordinary pressure and has to be compressed to the requisite extent prior to its admission into the gas producer. In certain cases, however, it is preferable to generate the necessary oxygen by the electrolysis of water under pressure, the oxygen being then obtained direct with a pressure which may correspond to the gasification pressure, so that the otherwise essential compression is unnecessary. At the same time, the hydrogen generated under pressure can be employed for enriching the purified gas with hydrogen, or the gas introduced into the hydrogenation zone, or also directly used for the hydrogenation treatment.

The process of the present invention enables a valuable high-power gas tobe produced, which has a composition similar to that of coal gas, and the process also, furnishes a good yield of light oils at the same time. The yield of light oil is dependent upon the character of the fuel used. Under the same conditions, from two fuels of difierent bituminous content, in one case 2.3 per cent of light oil was obtained, and in the other case, only 1.1 per cent. The yield of light oil can, however, be substantially increased by raising the pressure, by use of catalysts, and by providing the abovedescribed hydroge ation zone. The plant can be adapted so as to furnish more gas or more oil, according to the state of the market, by varying the working conditions. Although the process directly furnishes a gas of the requisite pressure for remote supply purposes, the only work of compression needed is that for the relatively small quantities of oxygen required in the process.

I claim:---

1. Process of producing a gas having a calorific value at least as high as water-gas which comprises gasifying a solid carbonaceous fuel in the absence of foreign catalytic agents materially affecting the reaction under a pressure greatly in excess of two atmospheres with a gasifylng agent consisting essentially of oxygen and steam in such regulated proportions that the gasification temperature is maintained at about 600 to 900 0., whereby a considerable quantity of methane is produced.

2. Process of producing a gas having a calo- 7 riflc value at least as high as water-gas which comprises introducing a mixture comprising a solid carbonaceous fuel and a catalyst into a gasifying chamber and gasifying said fuel therein under a pressure greatly in excess of two atmospheres with a gasii'ying agent consisting essentially of oxygen and steam in such regulated proportions that the gasification temperature is 'maintained at about 600 to 900 0., whereby a portions that the gasiflcation temperature is,

maintained atabout 600 to 900 C., whereby a considerable quantity of methane is produced.

4. Process as claimed in claim 1 wherein the .pressure is at least 15 atmospheres.

5. Process as claimed in claim 1 wherein the pressure is to 50 atmospheres.

6. Process of producing a gas having a calorific value at least as high as water-gas which comprises gasifying a solid carbonaceous fuel in the absence of foreign catalytic agents materially affecting the reaction under a pressure greatly in excess of two atmospheres witha gasifying agent consisting essentially of one part by volume of oxygen and about 6 to 10 parts by volume of,

steam.

7. Process of producing a gas having a calorific value at least as high as water-gas which comprises introducing a mixture comprising a solid carbonaceous fuel and a catalyst into a gasifying chamber and gasifying said fuel therein under a pressure greatly in excess of two atmospheres with a gasifying agent consisting esentially of one part by volume of oxygen and about 6 to 10 parts by volume of steam.

8. Process of producing a gas having acalorific value at least as high as water-gas which comprises gasifying a solid carbonaceous fuel in the absence of foreign catalytic agents materially affecting the reaction under a pressure greatly in excess of two atmospheres with a gasifying agent consisting essentially of one part by volume of oxygen and about 6 to 10 parts by volume of steam at a temperature of about 600 to 900 C.

9. Process as claimed in claim 8 wherein the pressure is at least 15 atmospheres. I

10. Process as claimed in claim 8 wherein the pressure is 20 to 50 atmospheres.

11. Process as set forth in claim 1 wherein the fuel is gasifled in a state of suspension.

12. Process as claimed in claim 1 wherein the greater portion of the carbon dioxide contained in the gas produced is removed therefrom without substantially lowering its pressure.

13. In a process of producing a gas having a calorific value at least as high as water-gas which comprises gasifying a solid carbonaceous fuel in. the absence of foreign catalytic agents materially affecting the reaction under a pressure greatly in excess of two atmospheres with a gasifying agent consisting essentially of oxygen and steam in such regulated proportions that the gasification temperature is maintained at about 600-900 0., the gasii'ying agent being passed through a column of the fuel from the bottom, the steps of withdrawing at least a portion of the hydrogen containing gas from the gasification zone of the column, removing from this gas steam, carbon dioxide and sulfur compounds, heating the same and passing it into intimate contact with the fuel above the gasiflcation zone.

14. In a process of producing a gas having a calorific value at least as high as water-gas which comprises gasifying a solid carbonaceous fuel in the absence of foreign catalytic agents materially affecting the reaction under a pressure greatly in excess of two atmospheres with a gasifying agent consisting essentially of oxygen and steam in such regulated proportions that the gasification temperature is maintained at about'600-900 C., the gasifying agent being passed through a column of the fuel'from the bottom, the steps of withdrawing gas at the top of the column of fuel, removing therefrom steam, carbon dioxide and sulfur compounds, heating the purified gas and passing the heated gas into intimate contact with the fuel above the gasiflcation zone.

. OTTO

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