DE2750725A1 - Prodn. of sulphur-free synthesis gas in high-temp. melt - in presence of high-basicity solid slag-forming material - Google Patents

Abstract

CO/H2 mixt. free from sulphur are made by passing carbonaceous fuel and at least one oxidising gasification agent into a melt, pref. of metal, in presence of one or more solid materials to remove the sulphur, pref. highly-basic slag-forming solids. Used esp. for prodn. of synthesis gas from coal. High-basicity slag-forming materials can be used at below their m.pt., so that thermal stresses on the refractory lining of the reactor are reduced. Removal of slag is simplified, and reactor volume and cost reduced, giving a more economic and easily operated process.

Description

Method and device for the production of an essentially

Lichen CO and H2 containing gas The invention relates to a method as well as a device for the production of an essentially CO and H2 containing, approximately sulfur-free gas by gasifying carbon-containing and sulfur-containing Fuels in a melt, preferably metal melt, in which fuel as well as an oxidizing gasifying agent are introduced, the sulfur being chemically is bound.

In a known method, a molten bath is used which consists of a heavier phase of liquid iron and a lighter phase of liquid slag covering it. Fine-grained coal is continuously introduced into the iron via a water-cooled lance, and at the same time air or oxygen (DOS 1 915 248) or a mixture of oxygen and water vapor (DOS 1 955 115) as a gasifying agent via a second lance. To generate and maintain the slag, additives such as lime etc. are added to the molten iron in order to obtain a slag of sufficient basicity. The coal is reacted with the gasifying agent as it passes through the molten bath to form a gas which essentially consists of a mixture of carbon monoxide and hydrogen. The sulfur contained in the coal is initially bound to the liquid iron in the form of iron sulfide. This iron sulfide is replaced by the free calcium monoxide present in the slag after the reaction converted to calcium sulfide and iron oxide. At the same time, the iron oxide is replaced by the carbon after the reaction reduced to metallic iron. The sulphurous, liquid slag is withdrawn from the process, cooled, granulated, desulphurised and at least partially returned to the cycle.

The known process works - as I said - with a melt pool, in which both iron and slag are in the liquid phase. With this one Processes are perceived as disadvantages that: - optimal desulfurization high basicity the slag requires, which leads to very high melting temperatures, - high working temperatures result in correspondingly high heat radiation losses, - the Process control is technologically difficult, especially at higher process pressures, mainly because the slag change is associated with difficulties, - Due to the high layers of slag, a relatively large reactor volume is necessary is, - the temperatures increasing with the basicity, especially of the liquid slag a disproportionate stress on the refractory lining of the reactor Have consequence.

The object of the invention is therefore in particular to provide the above Disadvantages to be overcome in order in this way to an improved method and to arrive at a more advantageous device which in particular enables to work with relatively low temperatures with high basicity of the slag, without stressing the refractory lining of the reactor; the slag change to facilitate; the reactor volume and, as a result, the investment costs to reduce, and overall thereby to a more economical and easier to handle, to get more advantageous process.

The object is achieved in that a for the sulfur uptake or several solid substances, preferably highly basic slag formers in the solid phase be used.

This is expediently achieved in that the temperature of the melt is below the melting temperature of the solid substances and / or the slag-forming substances.

For this purpose, use can be made of the measure, that the basicity of the solids and / or the slag formers set so high is that their melting temperature is well above the melting temperature of the melt lies.

The basicity of the solid substances and / or the Slag former B = CaO + MRO + XO within the limits SiO2 + Al2O3 between 2 and 4, preferably set towards 3.

The carbon is preferably used together with the solid Substances and / or the slag formers introduced into the melt as a mixture.

In an embodiment of the invention, the possibility is also provided that a mixture of carbon and the solids and / or slag formation no as well as oxidizing gasification agent and this mixture in the melt is introduced.

The solids and / or the slag formers are in crumbly Condition in a grain spectrum between 0 to 30 mm, preferably with substantial Proportions between 5 and 10 mm.

It is advantageous here if a gas velocity is set becomes, in which the solids and / or the slag formers to the fluidized bed loosened and distributed approximately evenly in the gas flow.

The measure can advantageously be used in this state ensure that the solids and / or the slag formers are continuously discharged, regenerated and supplemented with fresh material, respectively after regeneration in the cycle be fed back into the process.

In this case, the solid substances and / or are preferably discharged the slag former from the process by pneumatic transport of the product gas.

In a further embodiment of the method according to the invention it is provided that that the solids and / or the slag formers classified during regeneration and the resulting oversized grains are crushed.

In this case, the solid substances and / or are expediently separated out the slag builder from the gas flow by centrifugal force.

In an embodiment of the method according to the invention, it is further provided that the solids melt in one place between and deposition are brought into intimate contact with the product gas in a fluidized bed.

This measure can be particularly useful when there is a separation the ash layer that forms on the weld pool and the solid matter required should be.

Because with the invention the difficulty of withdrawing liquid slag omitted, use can be made of the measure that the process carried out at a pressure level between 1 and 50 bar, preferably between 3 to 40 bar will.

As is known per se, the intensity of the exchange of substances is determined between the product gas and the solid substances in contact with the gas and / or the slag formers improved.

In order to physically condition the gas for further use, that is, to relax from its pressure level and from its temperature level down, it is proposed with the invention that this measure by Relaxation as well as through the transfer of heat to a work medium takes place through which converts heat into mechanical energy, preferably with the help of a hot air turbine is converted.

A device for carrying out the method is identified by a pressure-tight, temperature-resistant reactor with facilities for introduction of gaseous, liquid or solid reactants below the surface of the metal bath as well as with a cassette collecting space for the product gas and an adjoining line for discharging gas, solids and / or slag formers, which are fed into a separator opens, at the discharge leading through a gas-tight lock a regeneration vessel for the solids and / or the slag formers is connected, its solids discharge with a transport device for the return of the basic mineral component communicates in the reactor.

In an embodiment of the device it is provided that the clean gas discharge of the cyclone to the primary side of a heat exchanger via an expansion device is connected, the secondary side of which is used as a coolant from the working fluid of a Hot air motor, preferably a hot air turbine is flowed through.

As I said, the invention is based on the state described at the beginning the technology, whereby the well-known basic principle of process control is the so-called Molten-Iron-Process (MIP) is, and expediently, a reactor of the OBM type (Oxygen-Bottom-MaxhUtte) is used, through whose bottom nozzles the reagents carbon, Desulphurising agents and gasification media such as O 2, H 2 O, air, etc. are blown into the molten iron. The gas can be desulphurised with all common and known desulphurisation agents from the elements Ca, Al, Mg etc., which have a higher heat of formation have as FeS.

The process temperature is, however, in the method according to the invention in contrast to the prior art so controlled that solid substances, for example CaO, MgO etc. as well as other slag formers in unmelted form are preferred are present in a thin layer on the molten bath, namely below the melting point by CaS.

If, as it corresponds to a preferred embodiment of the invention, for example an intimate mixture of fuel, Ca0 and an oxygen-containing one Gas in preferably finely divided form through an arrangement of bottom nozzles into the Melt are blown in, it is effected with this measure that already during the penetration of the sulfur-binding reagents through the melt the initially The reaction chain described takes place, so that essentially above the melt Product gas containing CO and H2 in addition to containing essentially basic sulfides solid mineral components is present.

CaS particles and ash components of the coal become common excreted from the melt as solid substances or as slag formers and initially form a layer on the melt.

As the gas velocity increases, this layer becomes the gas flows through it so strongly that a fluid bed-like state is achieved, whereby components of the solid matter end up with high gas velocities discharged by the gas flow and in the downstream cyclone or

another downstream filter separated into pure gas and solids will.

The amount of solids and / or to be discharged per unit of time is here Slag forming by the particle size, gas velocity and slag layer height adjustable within adjustable parameters of the process sequence.

One made from components of coal ash and blown mineral Layer of solids and / or slag formers formed by desulphurising agents can for example have the following composition: Si02: 20 - 25% Al2O3: 5 - 15% CaO: 50 - 60 s FeO: O - 5 X MgO: O - 10 X MnO: 0 - 5% Alkalis: o - 5% There are deviations from this exemplary composition permissible as long as the basicity of the components is not significantly changed.

Their acidic constituents, for example Si02, A1203 must have over the Addition of basic components, e.g. CaO, MgO, are overcompensated, to ensure a high desulfurization potential.

The discharged and separated from the gas stream or solids Slag components can be stored in a separate B-container using 02 or H20 steam or a mixture of both - as is known per se - to be desulphurized, whereupon the sulfur-free mineral is returned to the gasification reactor as regenerate, while the released gaseous SO2 is fed to a CLAUS system, for example becomes, as is also known per se.

In the following the invention is illustrated with reference to drawings and explained in more detail. They show: FIG. 1 the block diagram of an installation for production a reducing gas FIG. 2 shows the block diagram of the part of the installation for expansion and heat transferring the product gas to a hot air turbine.

In FIG. 1, the reactor 1 is arranged on a frame 2.

As is known per se, there are 3 rivers at the bottom of the reactor for blowing the reactants into the bottom area 4 of the reactor 1.

The reactor 1 is up to the level of the bath level 5 with liquid iron 6 filled. A solid layer 7 can be seen above the iron level 5 basic mineral or slag components. This layer 7 is due to high gas velocities of the product gas emerging from the liquid iron bath 6 in a fluid bed-like state, with the result being in the conical head part 8 of the reactor 1 with the tapering of the flow cross-section resulting increase the flow rate of the gas components of the solid layer discharged and through the subsequent Line 9 due to the high speed be dragged along. This line 9 opens tangentially into the separating cyclone 10, a gas-tight lock 11 is arranged at its solids discharge, while the Clean gas, indicated by the arrow 12 with the clean gas line 13, leaves the cyclone 10.

The discharged solids, essentially basic sulfides, get there through the transport device indicated by the number 14 into the regeneration vessel 15. In it, the chemically bound sulfur of the sulfides is replaced by oxygen 16 and / or superheated steam 17 volatilized to SO2 and discharged via line 18, while the solids freed from the sulfur, for example Ca0 through a lock 19, as well as a schematically indicated transport device 36 discharged and after Processing in a processing facility only shown as a black box 20 is fed back into the process. Because of the ash from the coal will, as in itself known from the circulating basic Sulfur carrier In each case a partial stream is removed and a new basic stream is added Material such as calcium oxide, magnesium oxide etc. supplements.

2 shows the conditioning of the product gas in a block diagram through pressure release and temperature reduction.

The one leaving the high-performance separator 10 through the clean gas line 13 After expansion in expansion nozzles 21, product gas 12 flows through the primary part 22 of the heat exchanger 23 passed through. It leaves the heat exchanger 23 through the gas line 24 for further use.

The working medium circuit is on the secondary side 25 of the heat exchanger 23 26, 27 of a hot air turbine 28, which is mounted on a composite shaft 29 the power part 30, the compressor part 31 and the power consumer 32, in the present case Case has an electric generator. Between the exhaust pipe 33 of the turbine 30 and the suction side 34 of the compressor 31, a heat exchanger 35 is arranged, which is the gas temperature of the circulating working fluid which is at this point has a relatively low temperature level, continues to cool, and with the removed Amount of heat, for example, a unit for generating service steam with thermal energy provided.

The conditioning of the gas with the help of a combined system The hot air turbine is particularly useful because it provides the possibility What is required is that with temperatures of approx. 1,400 OC and pressures of approx. 40 bar accumulating gas to relax and cool down easily.

The adiabatic expansion already results in part of the heat content converted by the gas into kinetic energy, which the operation of the heat exchanger 22 benefits, while the closed circuit of a hot gas turbine is the unproblematic one Possibility to lower the gas effectively by a few 100 OC in temperature and the energy gained with it in another, usable form of energy, in the present Trap electric current, convert.

The embodiment of a plant for gasification shown in FIGS. 1 and 2 v3n fuels containing sulfur to one containing essentially CO and H2 Gas is only to be understood as an example.

A variety of modifications and embodiments will be apparent to those skilled in the art accessible without further inventive step, provided they are one of the applicable Patent claims are sufficient.

Claims (18)

Claims 1. A method for producing a substantially Almost sulfur-free gas containing CO and H2 by gasification of carbon and sulfur-containing fuels in a melt, preferably metal melt, into which fuel and at least one oxidizing gasifying agent is introduced , whereby the sulfur is chemically bonded, which means that it is not possible to use it I do not know that one or more solid substances are preferred for the uptake of sulfur highly basic slag formers can be used in the solid phase. 2. The method according to claim 1, characterized in that the temperature the melt below the melting temperature of the solid material and / or the slag forming agents lies. 3. The method according to claim 1 and 2, characterized in that the The basicity of the solid material and / or the slag formers is set so high that that their melting temperature is well above the melting temperature of the melt lies. 4. The method according to any one of claims 1 to 3, characterized in that that the basicity of the solid material and / or the slag formers B = CaO + MRO + XO set within the limits between SiO2 + Al2O3 to 4, preferably towards 3 is. 5. The method according to any one of claims 1 to 4, characterized in that that the carbon is preferred together with the solids and / or slag formers are introduced into the melt as a mixture. 6. The method according to claims 1 to 5, characterized in that that a mixture of carbon and the solids and / or slag formers as well as oxidizing gasification agent and this mixture in the melt is introduced. 7. The method according to any one of claims 1 to 6, characterized in that that the solids and / or the slag formers in a crumbly state on the Melt are present. 8. The method according to any one of claims 1 to 7, characterized in that that the solids and / or the slag formers in a range of grains between 0 to 30 mm, preferably between 5 to 10 mm. 9. The method according to any one of claims 1 to 8, characterized in that that a gas velocity is set at which the solids and / or the slag formers are loosened to form a fluidized bed and almost evenly in the gas flow are distributed. 10. The method according to claims 1 to 9, characterized in that that the solids and / or the slag formers during or after the sulfur absorption continuously withdrawn, regenerated desulphurizing and in the cycle in the process to be led back. 11. The method according to any one of claims 1 to 10, characterized in, that the discharge of the solids and / or the slag formers from the process is preferred be done by pneumatic transport of the product gas. 12. The method according to any one of claims 1 to 11, characterized in that that the solids and / or the slag formers classified during regeneration and the resulting oversized grains are crushed. 13. The method according to any one of claims 1 to 12, characterized marked that the separation of the solids and / or the slag formers from the gas stream done by centrifugal force. 14. The method according to any one of claims 1 to 13, characterized in, that the solids in a place between the melt and separation in a fluidized bed be brought into intimate contact with the product gas. 15. The method according to any one of claims 1 to 14, characterized in that that the process at a pressure level between 1 and 50 bar, preferably between 3 to 40 bar is carried out. 16. The method according to any one of claims 1 to 15, characterized in that that the physical conditioning of the product gas preferably by relaxation as well as through the transfer of heat to a work medium, which serves to Converting thermal energy into mechanical energy in a work process. 17. Device for performing the method according to one of the claims 1 to 16, characterized by a pressure-tight, temperature-resistant reactor (1) with devices (3) for introducing gaseous, liquid or solid reactants under the surface (5) of the melt (6), and with a gas collection space (8) for the product gas and an adjoining line (9) for discharging solid gas Substances and / or slag formers (7) which opens into a separator (10) its discharge (14) passing through a gas-tight lock (11) is a regeneration vessel (15) for the solids and / or the slag formers is connected, its Solids discharge (19) with a transport device for the return of the basic Mineral component in the reactor (1) is in connection. 18. The device according to claim 17, characterized in that the Clean gas discharge (13) of the separator (10) preferably via at least one expansion device (21) is connected to the primary side (22) of a heat exchanger (23) whose Secondary side (25) of the working fluid of a hot gas engine, preferably one Hot air turbine (28) is traversed as coal medium.