DE2748214A1 - METHOD AND DEVICE FOR DESULFURIZING A WARM REDUCING GAS - Google Patents

Description

Method and apparatus for desulfurizing a warm reducing agent Gas

The invention relates to a method and a device for desulfurizing a warm reducing gas, in particular such a gas, which is produced by the combustion and gasification of sulphurous, carbonaceous fuels or fuels is formed. The gasification of solid carbonaceous fuels, like reacting with a limited amount of oxygen for the purpose of producing carbon monoxide is well known. Either pure oxygen or air can be used for this implementation be used. The products of combustion form a reducing gas, which is carbon monoxide and usually hydrogen contains. Carbon dioxide, water vapor and nitrogen can also be present in the reducing gas. Hydrogen is made from the Hydrocarbons are formed in the fuel, while nitrogen is introduced by air or also contained in the fuel can. Carbon dioxide and water vapor can also be used alongside

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TELEX OS-SW S «O TtLISRAMME MONAPTH TELECOPER

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Oxygen to react with the carbonaceous fuel as well as with the reducing gas formed therefrom can be used to determine the final composition of the resulting reducing To change gas.

One of the difficult problems with the gasification of carbonaceous Fuels is that many commercially available carbonaceous fuels contain sulfur. Sulfur-containing reducing gases, which usually contain primarily hydrogen sulfide, are generated when these Fuels used in the gasification process with air or oxygen will. These sulfur-containing gases in the reducing gas are often disadvantageous for a number of reasons. A The main reason, of course, is that the ingress of sulfur into the air creates severe emissions problems.

Many efforts have already been made to remove the sulfur from the combustion of the fuel with air or Remove oxygen from the sulfur-containing fuel. Other efforts have been directed towards the sulphurous Remove gases after the fuel has been gasified. However, both problem-solving efforts failed because of their high investment costs and high operating costs do not enforce.

Other efforts have been made to remove the sulfur during the gasification reaction. U.S. Patent 3,533,730 describes an embodiment of such a method in which the carbonaceous fuel is below the surface an iron melt with a controlled amount of oxygen is implemented and with which lime on the surface of the weld pool is used to remove the sulfur from the weld pool to desorb. The sulfur is then from the molten, Ash-lime-sulfur-slag by-product

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fenit. With regard to the practicality of this However, serious problems still remain in the process. The amount of fuel gasification depends for a given melt size (Melt volume) depends on the size of the fuel solution. aside from that the sulfur can only be removed from the slag by-product by costly additional measures. Bas gasification product generally contains fly ash, which likewise can only be removed by additional measures.

Desulfurization of warm fuel gases is currently the subject of extensive research, particularly because it can lead to thermally efficient power generation in coal-based combined systems. Hot gas desulphurization also includes advantages for the direct reduction of iron ore based on coal. The use of calcined dolomite has been proposed for desulfurization of warm reducing gases, for which reference is made to U.S. Patents 3,276,203, 3,307,350 and 3,853. Dolomite is an effective gas desulphurisation agent but the generally proposed method for dolomite regeneration, in which COg and B ^ O are reacted under slightly reducing conditions, at pressures of more than about 0.35 at and temperatures of preferably more than 540 to 650 ° C to release HpS does not guarantee complete fly generation of the dolomite. In addition, the continuous use of dolomite for gas desulfurization purposes with subsequent hegnerization leads to reduced regeneration performance until after about 10 cycles the dolomite only has about 10 to 20 % of its original desulfurization capacity. In addition, since the spent dolomite contains considerable amounts of unregenerated calcium sulfide, it must be subjected to an expensive and complete treatment in order to bring it into a condition suitable for landfill, so that

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Air and groundwater pollution are avoided. Becomes dolomite after regeneration by means of the above If the process is calcined, sulfur residues remaining in the sulfur can be released, which is a complicated treatment of the exhaust gas required to clean it so that it can be released into the atmosphere.

The present invention relates to an improved method for desulfurizing warm reducing gases and according to the invention the gas is contacted with a desulfurizing agent, the used desulfurizing agent is then regenerated and that regenerated desulphurising agents are then used for further desulphurisation of warm reducing gases. The invention relies on the use of a warm copper melt as a desulphurizing agent and proposes the regeneration of the exhausted Desulfurization agent by contacting the copper sulfide, which is a by-product, with an oxidizing agent Gas atmosphere. Preferably, the heat reducing gas is obtained by gasifying a sulfur-containing carbon-containing one Fuel, such as finely divided coal, is produced. Plug ash is preferably removed from the hot gas stream in that the Gas is passed through the molten copper sulfide by-product of the gasification process.

Compared to the prior art, this has the advantage that no lime is consumed and that this is used as a desulfurizing agent copper used is easy to regenerate. Fly ash in the warm reducing gas can also be easily removed and do not impair the ability of the desulphurising agent to regenerate.

Another advantage of the process is that the copper sulfide by-product after reaction with oxygen in the

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Regeneration stage of the process forms easily marketable sulfur dioxide. In addition, depending on the type the oxidizing atmosphere used, the sulfur dioxide generated have any desired concentration. So can Use of pure oxygen in the pure regeneration stage Sulfur dioxide are generated. In contrast, the sulfur-containing slag of the process described in US Pat. No. 3,533,730 has to be cooled, granulated, wetted and contacted with carbon dioxide. The hydrogen sulfide gas evolved in the process must then be processed further to remove the sulfur. Thus, with the help of the method according to the invention, a very expensive and complicated procedure in the made essentially redundant.

In addition, the process according to the invention can easily be modified to a continuous process.

Any carbonaceous material that contains a reducing gas, how carbon monoxide and hydrogen forms. Suitable carbonaceous fuels are oil, coal, coal powder oil slurries, tar, and the like. It is important that the carbonaceous fuel be fluid. Thus, solid, liquid and / or gaseous fuels that are fluid can be used. In general, the sulfur content is this carbonaceous fuels between about 0.1 and about 5 Weight # lie. A preferred carbonaceous fuel consists of finely divided soles and in particular of coal with an average particle size of about 0.05 to about 2 mm. The warn molten copper according to the invention is on maintained at a temperature sufficient to gasify the carbonaceous fuel and to easily get with the copper

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implement, which is present in the carbonaceous fuel and / or io warinen reducing gas. A temperature of about II50 to about 1250 G ⁰ is preferable for the hot Kupferschaelze.

According to one embodiment of the method VaTTTi according to the invention, the set or specific amount of oxygen in the gasification step of the method can be made available as pure oxygen, as air or in the form of another suitable oxygen source.

Water vapor, preferably in the form of steam and carbon dioxide or mixtures thereof, can be part of the gasification process Embodiments of the invention can be added to deal with the carbonaceous fuel or the present reducing agent To implement gas. By changing the amount and the proportions of water vapor and carbon dioxide, the composition of the reducing gas generated can be changed accordingly.

The reducing gas produced has a low sulfur content, i.e. a sulfur content that is lower than with direct gasification of the carbonaceous fuel without breaking down sulfur from the gaseous product. In general, the reducing gas produced contains less than about 0.3 vol .-% hydrogen sulfide, the hydrogen sulfide content mostly between about 0.1 and about 0.3%.

Those in the generation stage of the method according to the invention The oxidizing gas atmosphere used generally consists of oxygen or a suitable source of oxygen, such as oxygen in the legs, Air or air enriched with oxygen.

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Preferably, the reducing gas produced is used for power generation or used for ore reduction or the like. The inventive method for producing hot reducing Gases is particularly suitable for the above purposes because it is not necessary because of the low sulfur content is to cool the gases and thereby lose expensive energy to remove the sulfur before using the gas in ore reduction, the energy generation or the like. To remove.

According to a preferred embodiment of the invention, the carbonaceous fuel is used together with oxygen in a controlled manner Way so injected into the copper melt or in the vicinity of the copper melt that the Reacting warm gases from the carbonaceous fuel with the copper melt to form a foam, consisting essentially of copper sulfide and coal ash Bubbles exist and form on the surface of the molten copper bath. The one containing copper sulfide Foam is released from the gasifier through a restricted opening along with the generated reducing gas passed through, so that the chemical reaction between the copper sulfide foam and the fly ash generated in the warm reducing Gas takes place, thereby producing an ashless reducing gas.

It is important that the warm reducing gases after the Invention carefully implemented with the molten copper in order to have a reaction of the sulfur in these gases to achieve the copper. This is preferably achieved by that a flow of such a gas with sufficient speed to achieve good mixing in the Melt is directed

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A preferred idea resides in a method and an apparatus for producing a poor v / poor reducing agent Gas by desulfurization of a warm reducing gas by contacting the warn sulfur-containing reducing gas Gas with hot molten copper to produce a gas and a copper sulfide by-product. The copper is then oxidized by heating the copper sulfide by-product of the desulfurization step in the presence of an oxidizing agent Regenerated gas atmosphere. According to a preferred embodiment, the warm sulfur-containing gas is gasified generated from a carbonaceous fuel. In addition, the warm reducing gas is preferably through the By-product of the desulphurisation stage consisting of molten copper sulphide is passed to the fly ash in this way to be removed from the gas flow.

Further features, advantages and details of the invention emerge from the following description of embodiments based on the drawing. In this shows:

Fig. 1 is a schematic representation of an embodiment of the desulfurization according to the invention and generation process as well as a device for their implementation and

2 shows a preferred device for carrying out the method according to the invention.

As can be seen from the drawing and in particular from FIG. 1, the desulfurizer 3 contains a bath of molten copper. Sulphurous warm reducing gas from a source 1 is introduced into the desulphurizer 3 by means of a line 2. The warm, reducing gas is preferably produced by the fact that a finely divided, sulfur-containing, carbonaceous

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Substantial fuel directly or indirectly into the melted Copper is introduced (injected, injected), whereupon a set amount of oxygen, steam and / or carbon dioxide is directed to or into the copper bath in such a way that gasification of the carbonaceous material takes place and that the generated sulfur-containing gas flow has such a speed and sifting that good mixing with the molten copper is guaranteed. The sulfur contained in the hot gas is reacted with the molten copper, whereby copper sulfide is formed as a reaction product. The hot gas and the oxygen are preferably used in the molten copper bath so added that a copper sulfide foam in the form of consisting primarily of copper sulfide and coal ash Bubbles appear on the surface of the copper melt pool. The copper sulphide is then removed from the desulphuriser via a line 5 3 withdrawn and fed to a regeneration device 6. Oxygen is transferred from an oxygen source 7 a line 8, which can be designed as an oxygen lance, is fed to the regeneration device 6 in order to be able to cope with it to implement the copper sulfide. In this way in the regenerator 6 copper produced is fed back to the gasifier 3 through a line 9. With the help of a line 10 is sulfur dioxide removed from the regenerator. Ash and other impurities are removed from the regenerator by means of a line 11 6 deducted.

Fig.2 shows a preferred embodiment of the invention Device with the help of which a carbonaceous fuel, such as finely divided coal, for the purpose of producing a warm reducing gas is gasified to form a by-product consisting of copper sulfide, the as Copper sulfide recovered by-product is regenerated and reused is used to add more sulphurous warm reducing agents

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Desulfurize gas. Molten copper 24 is turned into a Gasification device 25 introduced and implemented with sulfur-containing carbon-containing fuel, such as finely divided coal », which enter the gasification and desulfurization device 25 via lines 20 and 21, respectively. Oxygen, Steam and / or carbon dioxide is supplied via lines 23 and 21, respectively fed to the gasification and desulfurization device. The carbonaceous fuel and the set amount of oxygen or the like are directly or indirectly related in this way introduced into the molten copper that sulphurous, warm, reducing gases are formed with sufficient speed be to react with the molten copper to form a copper sulfide foam 26, which through a restricted or narrow opening, which is formed between the vessel walls 22 and 29, is passed through. Through this the copper sulfide foam 26 and the warise produced become reducing Gas, which is preferably carbon monoxide and hydrogen, for passage through the narrow forced opening, whereby the foam and the gas interact with each other and through the copper sulfide foam any ash is removed from the reducing gas. The heat mixture of copper sulfide foam and ash is in a storage chamber 27 deposited. The reducing gases produced pass from the storage chamber 27 through an outlet off, while the copper sulfide foam 26 is fed to a generator 32 with the aid of transport devices 31, where oxygen is introduced by means of a line 33 for the purpose of reaction with the by-product consisting of copper sulfide is so that copper is formed, which with the help of transport devices 38 removed from the gasifier 32 and again to the copper melt pool 24 for reuse in the gasifier 25 is supplied. The ashes and others Waste products are removed via an exit 36.

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Unused gases are withdrawn from an outlet 5 ^.

In the case of the partial combustion of coal, for example, according to the invention, almost the entire sulfur content of the coal is converted mainly to H ₂ S and COS, and these substances easily react with liquid copper to form CUp. The reaction with H ₂ S proceeds according to

2 Cu (i) + H ₂ S (g) = Cu ₂ S (1) + H ₂ (g) (1)

where the free energy and the equilibrium constant of the above conversion are given as follows:

-11,900 - 2.93 T kai. (2)

^H 2

log

The implementation with COS is proceeding accordingly

2 Cu (1) + COS (g) = Cu ₂ S (1) + CO (g)

* - 10,620 - 9.83 T kai. (5)

log -τ; = £ ^ + 2.148 (6)

^ COS T

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For the combustion product containing 55% CO and 35% H ₂ , the sulfur remaining in the gas at the Cu-Cu ₂ S equilibrium and 1200 ° C. amounts to 0.14% H ₂ S and 0.012 % COS. If air is used in the incomplete combustion of coal, a corresponding dilution or reduction of the residual sulfur content in the fuel gas can be observed. After combustion of the fuel gas (35% H ₂ ; 65% CO) with air, the exhaust gas contains about 0.043 vol .-% SOp and this value is below the currently permissible S0 ₂ emission limit.

In the conversion of Cu ₂ S to copper by blowing in air, the basic reaction is given by

Cu ₂ S (1) + O ₂ (g) = 2 Cu (1) + SO ₂ (g) (7) ⁰ = 52,930 + 8.47 T kai. (8th)

_{Since Cu 2} S is always present in the converter in this continuous process, there is only very little or no copper oxidation at all, which applies in particular to the small injection quantities required for this purpose.

As the above equation (8) shows, the reaction designated there is exothermic. For continuous operation without excessive heating of the bath, the converter and the blow nozzle or blow mold should be cooled with water. If necessary the blow mold or blow nozzle can be protected by using a so-called Q-BOP steel fresh blow mold in which the air flow is surrounded by a cooling gas.

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Assuming complete utilization of the copper in the desulfurization of the fuel gas and complete recovery of the copper in the conversion of the (k ^ S, the following material balance can be achieved: For a coal containing 3% sulfur and when burning one tonne of coal per minute 0.12 tons of liquid copper per minute to circulate to the converter and from the combustion chamber to control the sulfur in the fuel gas. This amount of circulated copper is well below the practical limit of copper regeneration from C ^ S in the converter. The developed electromagnetic Elevator conveyors are also very suitable for handling these modest amounts of liquid copper.

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Claims (1)

K. SCHUMANN ί *. , - _β ORHBlNAT. CWl.-PHYS P. H. JAKOB DlPL-INa. Pittsburgh, ⁸ MUNICH 22 MAXIMILIANSTRASSE 43 Pennsylvania 15230 U.S.A. October 27, 1977 P 12 105-4-3 / ku Claims 1. A method for desulfurizing a warm reducing gas, in which the gas contacted with a desulfurizing agent, then regenerated the exhausted desulfurizing agent and the regenerated desulfurizing agent is used again for desulfurization of other warm reducing gas, characterized in that a bath of molten sulfur as Ent sulfur Copper is used and the exhausted desulfurizing agent is contacted with an oxidizing gas atmosphere for its regeneration. 2. The method according to claim 1, characterized in that the temperature of the copper melt increases about 1150-1250 ° C is maintained. 3. The method according spoke 1 or 2, characterized in that the copper melt with carbonaceous fuel, such as finely divided coal, and with oxygen, water vapor, carbon dioxide or mixtures thereof is contacted to in situ a warm reducing gas with contents of vase material, carbon monoxide or To form mixtures of the same. 809819/0736 27482H 4 ·. Method according to one of Claims 1 to 3> thereby g e k e η η ζ ei chnet ^ that the desulphurized gas with Contacted copper sulfide in the exhausted Eatsclululfmittel is used to remove solid particles such as ash from the gas. 5 · Device for desulphurizing a warm, reducing gas with a device for contacting the gas with a desulfurizing agent, a device for regenerating the exhausted desulfurizing agent, and a device for recycling the regenerated desulfurizing agent for the purpose of desulfurizing further warm reducing gas, thereby gekennzeichn et that the desulfurizing agent comprises a bath (28) of molten copper and that the regeneration device a reactor (32) on v / eist, with the help of which the exhausted desulfurizing agent with a oxidizing gas atmosphere is contactable. 6. Apparatus according to claim 5> characterized through a deflector (29) for directing the desulphurized warm reducing gas through a copper sulphide foam (26), which is formed during the reaction of the sulfur with the copper (28), for the purpose of removing solid particles such as Ash, from the warm reducing gas. 7 · Device according to claim 5 or 6, characterized by an injector (20), with the help of which, in order to generate the warm, reducing gas in situ, the molten Copper (28) can be contacted with a carbon-containing fuel. 809819/0736