DE2421114B2 - PROCESS FOR THE PRODUCTION OF GASES FROM SOLID FUELS - Google Patents

Description

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The invention relates to a method of manufacture of gases from solid fuels, in which fuels with different reactivities gasified one after the other in gasification areas connected in series with the addition of gasification agent and the gas generated in the first area is fed into the second area as a gasification agent and in the latter a fuel is gasified which is more reactive than that gasified in the first area Fuel and the temperature in the first area is higher than in the second area.

From DT-PS 7 27 676 a method is known at which coals of different reactivity are successively added to a gasification process to extend the gasification of coal dust over a large temperature gradient. This well-known The process is carried out in such a way that the gas for the conversion of the solid fuels mil: the gasification agent Steam required heat is applied by a highly heated stream of circulating gas.

When the circulating gas has reached its peak temperature, the inert coal becomes this Circulation gas added after the circulation gas flow through the reaction between carbon and water 6s Steam has been cooled to a temperature at which the reaction is considerably slower expires, the more reactive coal dust subset becomes admitted Jan disadvantage of this known The method consists in that the implementation in both Gasification areas are not controllable to the extent necessary to with regard to the Economy and composition of the finished gas to achieve an optimal result. In other In connection with this, dry lignite is also described as extremely reactive

Through the DT-PS 196697 a procedure for Production of a tar and anhydrous gas from bituminous fuels known, in which two Generators are connected in series and the »pas of the ejst ££ ^ generator, which with tar-containing Fuel is charged, is passed through the second generator. The latter is said to be tar-free Fuel (coke, charcoal, anthracite) are gasified, so as to obtain a tar-free and anhydrous gas as the end product. Although with this Procedure two separate gasification areas provided, but the second generator can also be loaded with anthracite, a fuel that is not very reactive.

It is also known from DL-PS 14 444 a method for gasifying solid fuels in which hot Rraktionsgase, which a gas generator operated with dust or fine-grained fuel then passed through a layer of lumpy fuel to absorb some of the heat which is present in the gas leaving the gas generator to improve the economy of the procedure can be exploited. The responsiveness of the individual gasification areas However, the fuel used does not play a role here.

The invention is based on the object of designing a method of the type described in the introduction in such a way that that its economy is significantly improved, with the quality of the end product gas all Should meet requirements.

To solve this problem, the invention proposes that in the first area bituminous coal and in the second area, which is separate from the first area, lignite be gasified with the addition of an oxygen-containing medium, preferably an oxygen-water vapor mixture. Instead of hard coal and lignite, hard coal coke and lignite coke can also be used. When gasifying hard coal or hard coal coke, relatively high gasification temperatures must be maintained. If these are above the slag flow temperature, the reaction takes place e.g. B. at 1500 ° C instead so that a product gas with a temperature of about 1400 to 1500 ° C and a high content of carbon dioxide and water vapor is withdrawn. The invention enables the further utilization of this product gas by reacting it with lignite or lignite coke, which are still implemented at relatively low temperatures up to 700 ° C., for example, so that heat as well as carbon dioxide and water vapor contained in the gas produced in the coal gasification area are still can be largely exploited or implemented. Because of the separation of both gasification areas, the possibility also exists the reaction and the conditions under which they take place in both areas regulate independently tu.

According to a further proposal of the invention, the procedure can advantageously be such that in the

Gasification in the first stage the carbon conversion as far as possible and the gasification in the second stage with excess carbon not be carried out until the complete conversion of the carbon. In this way it is achieved that the end product has only a small residual content of H ₂ O and CO _2. The non-gasified Tefl of the fuel from the second stage can be passed into the first stage and gasified there together with the coal to achieve a further conversion .

A method of producing gases from solid fuels in which the gasification is not up to complete conversion of the carbon is carried out is known from DT-PS 5 60 782 per se However, it is a one-step process, in which the non-gasified part of the fuel for Is used for heating purposes.

The invention also provides the possibility of using hydrogen as the gasification agent of the first gasification area add, which is converted with the fuel to methane. This is usually done in one Temperature range from about 700 to 800 ° C.

Otherwise, if necessary, in the second gasification area additional heat can be introduced.

The heat required to carry out the process according to the invention can be obtained from nuclear reactors be won. Another possibility is to obtain the required amount of heat by burning to win the residual coke from the gasification process.

A further advantage of the method according to the invention is to be mentioned that with corresponding Selection of fuels certain undesirable components of the coming from the first area Product gas can be removed in the second gasification area. So it is possible to increase the catalytic effectiveness to use lignite coke to clean the product gas of the coal gasification from the first gasification area of tar constituents or the like. It is also possible to desulfurize the product gas from the first gasification area if the Ash of the fuel gasified in the second area has a correspondingly high basicity. Latter can if necessary by adding e.g. CaO or MgO containing additives to the second gasification area gasified fuels can be achieved.

Some exemplary embodiments of the invention are illustrated below with reference to the drawings Flow diagrams explained

F i g. 1 shows a process in which hard coal and lignite are reacted with a gasification agent containing free oxygen. A mixture of oxygen 2 and water vapor 3 and fine-grained coal 4 are introduced into the primary reactor 1, which operates at reaction ^{temperatures of 1500 ° C.} The product gas 5 which occurs at the reaction temperature mentioned above the slag flow temperature reaches the downstream secondary reactor 7. The slag 6 is for the most part discharged from the primary reactor 1. In the secondary reactor 7 reactive, possibly pre-carbonized brown coal is reacted with the product gas 5 originating from the primary reactor with the aim of reducing the content of oxidizing. Constituents, in particular CO2 and H2O, in the product gas 5 and reduce the content of possible harmful components such. B. hydrogen sulfide, by binding to basic ash components of lignite 8 - or to added lime - or the like to reduce. The product gas 10, which has largely been freed of harmful components and oxidizing constituents, and the AsChC ¹ S enriched with the harmful components of the product gas 5 thus exit from the secondary reactor 7.

2 shows the flow diagram of a process in which two solid carbon carriers are reacted with a hydrogen-containing gasification agent. This gasification agent 12, to which some water vapor can be mixed, is fed to the gasification reactor 14 ^{after heating in the heater 13 to approx. 500 0 C} The reacted inert, largely on their caking tendency freed by pretreatment of coal 4 passes in a first fluidized bed at about 800 to 900 ⁰ C for implementation; If there is a high water vapor content in the gasification agent, additional heating may be useful or necessary. The feed line for the heating medium is denoted by 19, the discharge of which is denoted by 20. The product gas emerging from the first fluidized bed 18 passes into a second fluidized bed 22, in which a temperature of 600 to 700 ^° C. prevails.In this fluidized bed, reactive, non-baking brown coal 8 is produced entered. As in the case of the fluidized bed 18, there is the possibility of external heating. The feed line and discharge line for the heating medium are denoted by 24 and 25, respectively. After the reaction, the product gas 10 and the free-flowing ash 27 leave the gasification reactor.

F i g. 3 shows the flow diagram of the Pattenhausen process. In operating at temperature of about 900 ° C the primary reactor 1 was finely granular, inert coal 4 is reacted with steam 3 of about 950 ⁰ C. The water vapor is added in large excess; In this way, the heat necessary for gasification is brought into the primary reactor 1, from which residual coke 33 is withdrawn. The product gas 5 leaving the primary reactor 1, which has a temperature of about 800 ^° C., contains large amounts of water vapor in excess. The heat contained therein is converted in the secondary reactor 7, which works at approx. 700 ^° C., with reactive brown coal 8, the water vapor serving as a gasification agent. The residual coke 37 can be mixed with the hard coal 4, which is fed to the primary gasifier 31. The end product gas 10 leaves the secondary reactor 7 at about 600 ^° C.

Fig. 4 shows the flow diagram of a Ausführungsbei game in which two solid carbon carriers are reacted with an oxidizing gasification agent, which consists essentially of water vapor. In the primary reactor 1, which operates at temperatures around 1000 ^° C., which is heated by a medium that enters through the supply line 41 and exits the discharge line 42, fine-grained, inert coal 4 passes together with water vapor 3, which can be offered in large excess, for implementation. The resulting product gas 5, which has a temperature of approximately 900 ^° C., is introduced into the secondary reactor 7 in order to be reacted there with reactive brown coal 8. The reaction, which takes place at temperatures of about 900 ^° C., can also be heated. For this purpose, a supply line 48 and a discharge line 49 are provided for a heating medium. The residual coke emerging from the secondary reactor 7

37 can be added to the primary reactor together with the hard coal 4 for further conversion will. With 27 the ash is referred to, which is withdrawn from the primary gasifier, the end product gas 10 emerges from the secondary reactor 7.

For this purpose 2 sheets of drawings

Claims (5)

Patent claims: 1. Process for the production of gases from solid Fuels, in which fuels only differ Reactivitiesa one after the other in gasification areas connected in series be gasified with the addition of gasifying agent and the gas generated in the first area as gasifying agent is passed into the second area and in the latter a fuel is gasified, which is more reactive «than the first area gasified fuel and the temperature f in the first area is higher than in the second area, thereby - that in the first bareich coal and in the second area, that of the first Area is separated, brown coal with the addition of an oxygen-containing medium, preferably one Oxygen-water vapor mixture, are gasified. 2. The method according to claim 1, characterized that in the gasification iia the first stage the carbon conversion is as extensive as possible and the gasification in the second stage with an excess of carbon not to complete conversion of carbon. 3. The method according to claim 2, characterized in that the non-gasified part of the fuel from the second stage to the first stage. 4. The method according to claim I, characterized that hydrogen is added to the gasification agent of the first gasification area. 5. The method according to any one of the preceding claims, characterized in that in the second Gasification area additional heat is introduced.