GB1593178A

GB1593178A - Method of producing electrical energy and gas from coking coal prepared as coal dust

Info

Publication number: GB1593178A
Application number: GB51644/77A
Authority: GB
Original assignee: L&C Steinmueller GmbH
Current assignee: Hitachi Zosen Inova Steinmueller GmbH
Priority date: 1976-12-31
Filing date: 1977-12-12
Publication date: 1981-07-15
Also published as: AU3189377A; JPS5388805A; DE2659751A1; JPS6032672B2; FR2376200A1; AU518342B2; ZA777681B

Description

(54) METHOD OF PRODUCING ELECTRICAL ENERGY AND GAS FROM CAKING COAL PREPARED AS COAL DUST (71) We, L. & C. STEINMULLER GmbH, a German Company, of 527 Gummersbach, Germany, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The invention relates to a method of producing electrical energy and gas from caking coal prepared as coal dust.

The scarcity of the energy carriers oil and natural gas and associated commerical and political measures are leading to an intensified use of the energy carrier coal, on the one hand for the production of current, on the other hand, in the foreseeable future for the production of gases for use in chemistry and metallurgy. At the same time, in order to protect the environment, a number of official regulations has been issued, which include, inter aia, the restriction of the emission of sulphur dioxide. Since the sulphur content in coals may amount to several percent, in the Ruhr region on the average about 1 1%, the operators of power stations are forced, as distinct from former power station ideas, to use or develop new technologies in power stations or to continue and end developments previously started.

The power stations of the large current supplying organisations, with their block sizes of 600 of 800 MW are thermodynamically optimized, which has undoubtedly led to considerable savings in fuel. Improvements in the total efficiency can therefore only be sought in coupling processes such as the connection of steam-turbine and gas-turbine processes. In the firing of the gas turbine, gas, generally natural gas, is burnt with such a high excess of air that this waste gas, after performing work in the gas turbine, can be introduced into the firing of the steam generator as highly preheated combustion air. In this case, apart from the coal for the firing of the steam generator, natural gas has to be bought for the firing of the gas turbine, although this high quality energy carrier could be used more usefully and effectively in chemistry and metallurgy.

New technologies, with which both the fuel for the steam generator and for the gas turbine can be produced from coal, are therefor acquiring ever great importance in powerstation operation. Attempts at developing such technologies or at developing existing ones further, are therefore to be observed wherever coal is present in sufficient quantites.

In former developments, because it was not necessary, no attention was paid to the harmful substances carried into the atmosphere with the flue gases of the power station, for example, the elimination of which is compulsory today. New technologies in power stations must therefore include not only the production of the fuels but also the elimination of harmful substances, at least to such an extent that the permissible emission values are not exceeded.

Methods are known whereby the flue gases from a power station are desulphurized before being discharge into the atmosphere.

Since gypsum is produced with the majority of tE e,e methods, another environmental problem can easily arise, namely the question of disposal if the relevant industry can one day no longer utilize the gypsum produced.

In addition, this technology only solves one problem, namely the cleaning of the flue gases, but not the supplying of the gas turbine, for example.

Other proposals are concerned with the complete gasification of coal in order to make the fuel available, after cleaning, in gaseous form for the gas turbine and the steam generator. Desulphhurization of the flue gases is then no longer necessary. This technology does not meet the demand of the power station for maximum readiness for operation because the steam generator is only designed for gas firing, possibly even for an increased combustion-chamber pressure. In the event of a disturbance in the gas generating plant, the whole power station is out of operation. The costs of such a stoppage are very considerable so that it is required of new technologies that, in the event of failure of the gas production, at least the steam turbine section should be kept in operation.It should be possible to decouple gas production and current production, that is to say on failure of the gas production, the steam generator should continue to be operated by means of coal low in sulphur kept in store.

Conversely, it might be necessary, even though it is not very probable, on failure of the steam section, to continue to operate the gas producing plant with the following gas turbine.

Methods have also been proposed for this purpose, wherein synthesis gas for use outside the power station and for the gas turbine and possibly for the steam generator is produced by partial gasification of coal ground into dust and the coke dust remaining after the partial gasification is used as fuel for the steam generator. The sulphur introduced into the steam generator with the coke dust is also regulated by the degree of partial gasification, in such a manner that, for example, a greater amount of gas is produced by increasing the degree of partial gasification and the excess gas is burnt, after following cleaning, in the steam generator, with a correspondingly smaller amount of coke dust.

This method has the disadvantage that in order to use the gas outside the power station, a synthesis gas has to be produced at great expense, which admittedly meets the demands of the users situated outside the power station but is not needed in this high quality form inside the power station.

It is therefore the object of the present invention to indicate a method wherein, in order to produce electrical energy and gas from caking coal prepared as coal dust, the fuels for the gas turbine and the steam generator as well as the gas for other applications, are produced so as to meet the particular demands.

According to the present invention there is provided a method of producing electrical energy and gas from caking coals prepared as coal dust, characterised by the following method steps: a) The coal dust prepared to less than 01 mm, is subjected, after intermediate bunkering or coming direct from the comminution, to a rapid oxidation at a temperature higher than 380C" in less than 6 seconds, during pneumatic conveying with gases containing oxygen, b) The rapid oxidized coal dust, together with the oxidation agent, with the single or repeated addition of further oxygen carriers, is rapidly carbonized at temperatures above 750"C and treatment times shorter than 6 seconds and/or is rapidly partially gasified, in one or more stages during pneumatic conveying, while at the same time being desulphurized during the rapid carbonization and/or partial gasification, the heat requirements for the carbonization and/or partial gasification being provided by partial combustion of the coal and/or gas and/or tar, c) The coke dust formed by the rapid carbonization and/or partial gasification is supplied, hot or after cooling, wholly or partially to a steam generator producing steam for driving an electric generator, and the gas formed by the rapid carbonization and/or partial gasification is supplied, after cooling and cleaning, to a gas turbine and/or the steam generator.

d) The coke dust which is not supplied to the steam generator, while hot or after cooling, is rapidly wholly or partially gasified with gases containing oxygen, preferably oxygen itself, in one or more stages during pneumatic conveying, the resulting gases being supplied, after cooling, to a cleaning means and providing a source of gas for utilization as required, and the remaining residue of coke dust is supplied hot of after cooling to the steam generator.

It is of course to be understood that the cleaning of the gas prior to supplying the gas to a gas turbine and/or a steam generator or for utilization as required includes removing at least part of the sulphurous gases where necessary.

Examples of the method of the invention will now be described by way of example.

To obtain coal dust prepared to less than 01 mm, the coal can conveniently be ground first of all in a mill to grain sizes less than 0 2 mm and dried at the same time, the coarse components in the ground coal dust which are above 01 mm being separated from the remainder of the dust and returned to the same or a separate mill for further grinding.

Either flue gas from the steam generator of the power station or preheated air may be used for the drying. The heat for preheating the drying air can be taken from the hot gas produced during the carbonization and partial gasification, before entry into the gas cleaning means, and possible also from the hot coke dust. After separation of the coal dust from the flue gas or the grinding air, and intermediate bunkering, the coal dust thus prepared is supplied to a vehicle which at the same time is the oxidation agent for the preoxidation section. Particularly when air is used for the grinding and drying of the coal, an intermediate bunkering of the coal dust can be dispensed with, if the mill is capable, with correspondingly small amounts of air, to work under a pressure which exceeds the pressure loss in the following parts of the installation.

The oxidation agent may be predominantly air but may also be oxygen, for example, oxygen-enriched air or a mixture of oxygen and water vapour with an O2 content differing from 21% by volume. The stream of carrier gas or oxidation agent is preheated as highly as is economically tolerable, generally to temperature between 500"C and 700"C. It is also possible to reach temperatures of 1200"C and more by addition of a certain amount of gas and its combustion with the oxygen of the oxidation agent. The higher the pre-heating temperature of the oxidation agent, the higher the mixed temperature of oxidation agent and ground coal dust which becomes established and the lower the difference to reach the oxidation temperature.

This temperature difference may be overcome by direct heating, for example by means of a tube heat exchanger, in which case the heating medium-flue gas, steam or the likeflows through the tubes while the mixture of coal dust and oxidation agent flows round the tubes or vice versa. The heating may, however, also be effected by the direct transfer of heat, wherein the heat of a heating gas, here the oxidation agent at the same time, is transferred directly to the coal dust. The height of the preheating depends, in this case, on the charge, that it to say the weight of coal in kg per standard cubic metre of carrier gas, which is here the oxidation agent at the same time.With high charges, for example 2-3 kg of coal dust per m3 of oxidation agent, however, it is a prerequisite that during the transfer of heat from the heating gas (oxidation agent) combustible components emerge at least from some of the coal dust to be heated the heat of which is used by combustion for the further heating of the coal dust.

The heating operation is followed by the actual oxidation section for the transfer of the oxygen to the coal. Above certain temperatures, generally from 400"C, amounts of heat are released by the oxidation process which may exceed the radiation loss of the oxidation section and then lead to an increase in temperature of the mixture of dust and gas.

Up to the entrance into the carbonization and/ or partial gasification chamber, this temperature can be allowed to rise to the extent permitted by the materials used, for example 600"C. The oxidation temperature may also be kept constant, for example at 4200C, by indirect cooling-for example suspended heating and/ or cooling surfaces-or by the injection of water and hence the formation of water vapour. The water vapour formed with the last method of regulation then serves as a gasification agent in the partial gasification section, which uses the oxygen still contained in the oxidation agent after the oxidation section in the carbonization and partial gasification region to cover the heat needed by combustion of some of the coal and/or gas or other products from the coal.

After the preoxidation, also termed rapid oxidation, the coal dust, which no longer cakes on the surface, is supplied directly, with the conveying gas, which is the oxidation agent at the same time, and the gas components contained therein and formed during the rapid oxidation, to the carbonization and/ or partial gasification, where further oxygen carriers, preferably air, are introduced for the partial combustion of coal dust and/or other products from the coal to cover the heat requirements. Thus the preoxidized goal dust is brought very quickly, with heating speeds up to 100,0000C /min to the carbonization or partial gasification temperature, by direct heat transfer.

With the grain mixture from 001 mm, the average grain reaches the reaction temperature in less than one second, being already very largely carbonized and possibly also partially gasified. With the very rapid heating to temperatures above 750"C for the carbonization, above 1000"C for the partial gasification, the smaller grain fractions are heated up much more quickly than the coarser ones.The means that with a mixed temperature of for example 900"C, which becomes established after a certain time, fractions of, for example 0-20 mp may previously have reached temperatures of 1400"C and morethey then later surrender their heat to the cooler, coarser fractions-if room temperatures of, for example 1 5000C or more have been produced by partial combustion operations with the oxygen carriers introduced.

The additional oxygen carriers introduced at the beginning of the carbonization and/or partial gasification region, serve the purpose of producing the required temperatures by partial combustion of the coal and/or some of the gas formed and/or the other products formed during the carbonization or partial gasifications, for example tar, and of transferring the necessary heat to the coal dust to be heated up.

During the rapid carbonization and the rapid partial gasification-only seconds are available for these operations, the preoxidized coal dust becomes coke dust during the reaction and is then largely desulphurized.

Generally, up to 70% of the sulphur contained in the coal is converted into the gas form, namely hydrogen sulphide, by the rapid carbonization alone. This desulphurization can be still further increased by the rapid partial gasification. What is necessary for this is an appropriate disintegration of the coal grain on the way to the coke grain. The coke grain should, if possible, be carbonized to less than 3% of volatile components, because then the inner and outer surface of the coke grain is larger by factors often than that of the coal grain. The coke grain has very thin and multiple perforated walls, and components with a high affinity for sulphur, for example hydrogen-particularly in the developing state-can very easily reach these.On the other hand, care must be taken to ensure that the coke dust is, if possible, not conveyed for longer than 6 seconds in the carbonization and/or partial gasification gas at tempera tures of 1000 C and more, so that the hydrogen sulphide just formed does not decompose again and the sulphur gain accumulate in the coke dust.Obviously, for each coal, there is an optimum temperature for the desulphurization, which lies between 700"C and 1100 C, for Ruhr region fossil coal predominantly between 800"C and 950"C. Below and above this temperature, higher sulphur contents are found in the coke dust; at the lower temperatures because sufficient sulphur could not yet be decomposed, at the higher temperatures because certain reverse decomposition processes have taken place already. On the other hand, in the presence of carbon monoxide and hydrogen and a simultaneous high excess of carbon, carbon monoxide and hydrogen may again form solid carbon and water vapour if the temperatures in the reaction chamber are lowered below about 1000"C.

At a temperature of about 1000"C, less than 2 seconds are needed for carbonization down to a residue of less than 2% of volatile components in the coke dust. Higher temperatures should be used for the partial gasification of fossil coal because the partial gasification must also take place in seconds or fractions thereof.The partial gasification process can be repeated several times, as a result of the fact that high temperatures, for example 1400 C or more are produced at a plurality of successive points in the reaction chamber in the direction of flow by further addition of oxygen carriers and possibly also of water vapour, by partial combustion operations, and the resulting heat is transferred predominantly to the smaller fractions so that, for example, with a 4 or 5 stage partial gasification, the grain fractions up to 0-05 mm for example are gradually almost completely gasified in less than 4 seconds. The water vapour for the gasification can, like the oxygen carriers for the partial combustion, be introduced into the reaction chamber with the coal dust or coke dust and/or separately therefrom.This steam is preferably taken from a bleeder turbine, for example, after performing work, but can also be produced by heat transfer from the hot gas and/or coke dust to water.

Attention must further be paid to the hydrogen sulphide content of the gas which conveys the hot coke dust. This gas is composed of the stream of oxidation agent which comes from the rapid oxidation, of the combustion products of the oxygen carriers which were additionally introduced in the carbonization and/or partial gasification region, and of the gases resulting from the coal.

This mixture of gas components should not contain too much hydrogen sulphide because experiments have made it clear that with a proportion greater than 1%, a very distinct back decomposition of the hydrogen sulphide is effected. H12S contents less than 1% by volume should therefore be adhered to in the gas. It is most favourable to reduce this value to 0 3% by volume and less by the admixture of gas for example. In order to ensure both an adequate desulphurization and an adequate carbonization and/or partial gasification, less than 0 5% by volume of H2S should be aimed at in the carrier gas, and and dwell times in the carbonization and/or partial gasification chamber of 1-3 seconds and temperatures of about 1000"C or higher briefly.

The coke dust formed during the rapid carbonization and/or rapid partial gasification is then supplied wholly or partially, possibly after cooling, to a steam generator, while the carbonization and/or partial gasification gas is supplied, after cooling and cleaning, to a gas turbine and/or the steam generator.

It is not necessary to produce a gas with a high calorific value for combustion in the combustion chamber of the gas turbine and of the steam generator; it is sufficient for this gas to be combustible, possibly after preheating. Since the gas has to be cooled before it is cleaned, the amount of heat which corresponds to the temperature difference between carbonization and partial gasification region and gas cleaning means is returned to the products which are needed within the carbonization and/or partial gasification process, and possibly also the gas-turbine process, for example air, gas, oxygen, water vapour and coal.

The entry temperature into the gas purification is determined by the condensable components which are still contained in the carbonization and/or partial gasification gas.

In particular, it is a question of the tar and the like which, together with the dust still contained in the gas after the separation, may cause difficulties in heat exchangers if too greatly cooled. It depends on the nature and amount of the tar components, how high this cooling temperature must be.

Generally, it may be expected that it should not exceed 350 C, if there is no tar present it may be below 1500C. The cooling in the gas cleaning means from 350 C, for example, to below 100 C, is associated with a not inconsiderable loss of heat. The partial combustion of coal or gas to reach the necessary temperatures during the carbonization and/or partial gasification should therefore take place at least partially, in the reaction chamber so as to split up or burn the tar components emerging from the coal for example, and to use their heat to cover the heat requirements. Then the gas now free of tar can be cooled to less than 1 500C before the gas purification and this amount of heat can also be used here.

Since a gas having a relatively low calorific value is sufficient for the gas turbine ahd the steam generator, it is sufficient to carry out the rapid carbonization and/or partial gasification and also the rapid oxidation with air, possibly with the addition of water vapour. A preheating of the gas to be burnt after the gas purification can be effected by transfer of the heat from the hot gas and/or the hot coke dust. Thus a gas which just meets the demands of the gas turbine and of the steam generator is produced in the carbonization and/or gasification region.

If gas, for example, synthesis gas, has to be withdrawn from the power station for other users, some of the coke dust produced during the carbonization and/or partial gasification, generally carried out with air and possibly also with the addition of water vapour, is supplied not to the steam generator but to a following second, separate gasification plant, where the gasification is carried out with oxygen and/or water vapour. The coke dust, if it has not previously been cooled, enters this gasification plant at the temperature at which it left the carbonization and partial gasification, generally above 800 C. Here, too, oxygen and water vapour are preheated.They have taken the heat for this from the hot gas produced in the second gasification plant, possibly also from a remaining residue of coke dust or from the products of the preceding carbonization and/or partial gasification.

In the oxygen gasification plant, as during the carbonization and/or partial gasification with air, the oxygen carriers, here oxygen, may be supplied at one or more points, as may be the water vapour supplied. Thus, here, too, a very high temperature can be maintained over a long distance in the reaction chamber by partial combustion of coke dust and/or gasification gas. Whether a partial gasification or a complete gasification is carried out during the oxgen gasification in the second plant, depends on the operational circumstances. It may be advisable only to supply as much coke dust to the oxygen gasification as is necessary to produce the amount of gas needed from ths plant with complete gasification of the coke dust. A device already known for the complete gasification of the coke dust with oxygen could be used at this point for this purpose.

The separation of the gasification gas produced from any remaining residue of coke dust is again effected at the exit from the oxygen gasification. This coke dust is supplied to the firing of the steam generator or other utilization points; after surrendering its sensible heat, the gas is supplied to the media participating in the process or purified and possibly after further conversion, to users outside the power station.

Since no more condensable components are obtained during the oxygen gasification, the entry temperatures into the gas purification can be below 1500C.

If the recoverable amounts of heat from the gases produced and possibly from the coke dust are not entirely needed inside the gas production process, the preoxidation and possibly the grinding circuit, the excess can be used in the gas-turbine process to heat up gas and air and/or in the steam generator, for example for the preheating of feed water, superheating steam and the like.

The advantages of the present invention are: Far-reaching desulphurization of the coke dust supplied to the steam generator and/or other utilization points.

Production of purified gas obtained from the coal by rapid carbonization and/or partial gasification, preferably with air, for the firing of the gas turbine and/or of the steam generator, in a quality which is jsut sufficient for the requirements there.

Production of different kinds of gascarbonization, gasification with air or oxygen possibly with water vapour or the addition of water vapour with delivery of gases, for example synthesis gas, to customers outside the power station by partial gasification or complete gasification of hot coke dust, particularly coke dust which is capable of reaction.

Possiblility of burning coke dust, gas and mixtures of both in the steam generator.

Variable degree of partial gasification as a regulator for the desulphurization process and also for the gas supply in and to the power station.

Separation of gas and current production on failure of the gas production by use of coal low in sulphur.

WHAT WE CLAIM IS: 1. A method of producing electrical energy and gas from caking coals prepared as coal dust, characterised by the following method steps: a) The coal dust prepared to less than 0.1 mm, is subjected, after intermediate bunkering or coming direct from the comminution, to a rapid oxidation at a temperature higher than 380"C in less than 6 seconds, during pneumatic conveying with gases containing oxygen, b) The rapid oxidized coal dust, together with the oxidation agent, with the single or repeated addition of further oxygen carriers, is rapidly carbonized at temperatures above 750"C and treatment times shorter than 6 seconds and/or is rapidly partially gasified, in one or more stages during pneumatic conveying, while at the same time being desulphurized during the rapid carbonization and/or partial gasification, the heat requirements for the carbonization and/or partial gasification being provided by partial combustion of the coal and/or gas and/or tar,

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. steam generator, it is sufficient to carry out the rapid carbonization and/or partial gasification and also the rapid oxidation with air, possibly with the addition of water vapour. A preheating of the gas to be burnt after the gas purification can be effected by transfer of the heat from the hot gas and/or the hot coke dust. Thus a gas which just meets the demands of the gas turbine and of the steam generator is produced in the carbonization and/or gasification region. If gas, for example, synthesis gas, has to be withdrawn from the power station for other users, some of the coke dust produced during the carbonization and/or partial gasification, generally carried out with air and possibly also with the addition of water vapour, is supplied not to the steam generator but to a following second, separate gasification plant, where the gasification is carried out with oxygen and/or water vapour. The coke dust, if it has not previously been cooled, enters this gasification plant at the temperature at which it left the carbonization and partial gasification, generally above 800 C. Here, too, oxygen and water vapour are preheated.They have taken the heat for this from the hot gas produced in the second gasification plant, possibly also from a remaining residue of coke dust or from the products of the preceding carbonization and/or partial gasification. In the oxygen gasification plant, as during the carbonization and/or partial gasification with air, the oxygen carriers, here oxygen, may be supplied at one or more points, as may be the water vapour supplied. Thus, here, too, a very high temperature can be maintained over a long distance in the reaction chamber by partial combustion of coke dust and/or gasification gas. Whether a partial gasification or a complete gasification is carried out during the oxgen gasification in the second plant, depends on the operational circumstances. It may be advisable only to supply as much coke dust to the oxygen gasification as is necessary to produce the amount of gas needed from ths plant with complete gasification of the coke dust. A device already known for the complete gasification of the coke dust with oxygen could be used at this point for this purpose. The separation of the gasification gas produced from any remaining residue of coke dust is again effected at the exit from the oxygen gasification. This coke dust is supplied to the firing of the steam generator or other utilization points; after surrendering its sensible heat, the gas is supplied to the media participating in the process or purified and possibly after further conversion, to users outside the power station. Since no more condensable components are obtained during the oxygen gasification, the entry temperatures into the gas purification can be below 1500C. If the recoverable amounts of heat from the gases produced and possibly from the coke dust are not entirely needed inside the gas production process, the preoxidation and possibly the grinding circuit, the excess can be used in the gas-turbine process to heat up gas and air and/or in the steam generator, for example for the preheating of feed water, superheating steam and the like. The advantages of the present invention are: Far-reaching desulphurization of the coke dust supplied to the steam generator and/or other utilization points. Production of purified gas obtained from the coal by rapid carbonization and/or partial gasification, preferably with air, for the firing of the gas turbine and/or of the steam generator, in a quality which is jsut sufficient for the requirements there. Production of different kinds of gascarbonization, gasification with air or oxygen possibly with water vapour or the addition of water vapour with delivery of gases, for example synthesis gas, to customers outside the power station by partial gasification or complete gasification of hot coke dust, particularly coke dust which is capable of reaction. Possiblility of burning coke dust, gas and mixtures of both in the steam generator. Variable degree of partial gasification as a regulator for the desulphurization process and also for the gas supply in and to the power station. Separation of gas and current production on failure of the gas production by use of coal low in sulphur. WHAT WE CLAIM IS:

1. A method of producing electrical energy and gas from caking coals prepared as coal dust, characterised by the following method steps: a) The coal dust prepared to less than 0.1 mm, is subjected, after intermediate bunkering or coming direct from the comminution, to a rapid oxidation at a temperature higher than 380"C in less than 6 seconds, during pneumatic conveying with gases containing oxygen, b) The rapid oxidized coal dust, together with the oxidation agent, with the single or repeated addition of further oxygen carriers, is rapidly carbonized at temperatures above 750"C and treatment times shorter than 6 seconds and/or is rapidly partially gasified, in one or more stages during pneumatic conveying, while at the same time being desulphurized during the rapid carbonization and/or partial gasification, the heat requirements for the carbonization and/or partial gasification being provided by partial combustion of the coal and/or gas and/or tar,

c) The coke dust formed by the rapid carbonization and/or partial gasification is supplied, hot or after cooling, wholly or partially to a steam generator producing steam for driving an electric generator, and the gas formed by the rapid carbonization and/or partial gasification is supplied, after cooling and cleaning, to a gas turbine and/or the steam generator.

d) The coke dust which is not supplied to the steam generator, while hot or after cooling, is rapidly wholly or partially gasified with gases containing oxygen, preferably oxygen itself, in one or more stages during pneumatic conveying, the resulting gases being supplied, after cooling, to a cleaning means and providing a source of gas for utilization as required, and the remaining residue of coke dust is supplied hot or after cooling to the steam generator.

2. A method as claimed in claim 1, characterised in that water vapour is supplied to the carrier gas together with the coal or separately therefrom prior to rapid carbonization or partial gasification of the coal.

3. A method as claimed in claim 1 or 2, characterised in that water vapour is added to the oxygen-containing gases used for the 'gasification of the coke dust remaining after the intial cabonization and/or partial gasification of the coal dust.

4. A method as claimed in any of claims 1-3, characterised in that the said gases containing oxygen used for conveying the coal dust during the rapid oxidation consist of air.

5. A method as claimed in any of claims 4, characterised in that the oxygen carriers added during rapid carbonization and/or partial gasification of the coal dust consist of air.

6. A method as claimed in any of claims 1-7, characterised in that the heat drawn off during the cooling of the gas produced and/ or the cooling of the coke dust is used wholly or partially in the treatment of the coal by grinding, rapid oxidation, rapid cabonization and rapid partial gasification.

7. A method as claimed in claim 6, characterised in that when the heat drawn off during the cooling of the gas poduced and/or of the coke dust is partially utilized in the grinding, rapid oxidation, rapid carbonization and rapid partial gasification, the remaining residual heat is used in the steam generator or in the gas turbine process.

8. A method as claimed in any of claims 1-7, characterised in that when the coke dust produced is partially utilized in the steam generator and/or for the gasification, the remaining residual coke dust is supplied for use as a filler in coking plants, as a sintering fuel in sintering plants, as a substitute for lump coke in a blast furnace, as a reduction agent in other installations, as active coke dust as a substitute for active coal, or for the absorption of harmful gases.

9. A method of producing electrical energy and gas from caking coals prepared as coal dust, as claimed in claim 1 and substantially as hereinbefore described.

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