JPS61252290A - Method of refining high-temperature reducing gas - Google Patents

Abstract

PURPOSE:To efficiently remove a sulfur compd. contained in a reducing gas, by calcining an adsorbent on which a sulfur compd. contained in a high-temp. reducing gas has been adsorbed and using the obtained regenerated gas for pressurizing air or oxygen for desorption. CONSTITUTION:A coal, a heavy oil, etc., 1 is fed into a gasifying oven 3 where it is partially burnt with a small amount of air or oxygen 2 to obtain a high- temp. reducing gas 4. Coarse particle dust 6 contained in the high-temp. reducing gas 4 is removed with a dust-collector 5, and a fine dust 8 is removed with a precision dust collector 7 to obtain a gas 9. The gas 9 is fed into an adsorption-regeneration apparatus 10 where the gas is brought into contact with an adsorbent to remove a sulfur compd., thereby obtaining a refined gas 11. Air and/or oxygen 17 is fed into a regeneration apparatus 10 through a compressor 16 to calcine the adsorbent. The obtained SO2 gas 12 is fed through a gas cooler 13 and a blower 14 into a gas expander 20 to expand the gas. The power is transmitted to the compressor 16 which is coaxial with the gas expander 20 for use in pressurizing air for calcination.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a method for purifying a high temperature reducing gas, for example hydrogen sulfide contained in a high temperature reducing gas mixture such as the product gas of a coal gasification process. Concerning how to rationally remove.

(Conventional technology) In recent years, due to the depletion of oil resources and soaring prices, diversification of fuels (or raw materials) has been called for. Development of technologies to utilize crude oil (crude oil, vacuum residue, etc.) is progressing. A typical example is the method of gasifying coal or heavy oil to use as power generation, fuel, or synthetic raw material.

However, this gasification product gas contains hydrogen sulfide ranging from several hundred ppm to several 11,000 ppm, depending on the raw material coal and heavy oil, and this is used to prevent pollution, corrosion of downstream equipment, and poisoning of catalysts. , 1, it is necessary to remove it.

The necessary conditions for the hydrogen sulfide removal process from kernels are as follows.

(1) The gas produced by gasification is at a high temperature (furnace outlet.
00℃, 300-500℃ even if some heat is recovered) high pressure (
In the case of a pressurized gasifier), it is mostly used at high temperatures and pressures for downstream power generation (combined cycle power generation system that combines a gas turbine and a steam turbine), and as a fuel and synthetic raw material. Therefore, a dry method using high temperature and high pressure is advantageous from a thermoeconomic standpoint for the hydrogen sulfide removal process that occurs during the process. Incidentally, in the case of coal gasification power generation, it is said that there is a difference of 4 to 5 seconds in power generation efficiency between the dry method and the wet method.

(2) It is preferable to use by-products that meet the needs in terms of handling or marketability. When the gasification process begins to be used for power generation, fuel, and synthetic raw materials, the amount of by-products will be enormous, and the impact on related markets will be large, and the form of the by-products is an important factor.

(3) The process must be simple and rational. In practical application, the economic efficiency of the plant (fixed cost + operating cost) will ultimately be evaluated, so it is most important that the process be simple and economical.

(4) It is necessary to have high reliability regarding stable operation of the plant. Since it is incorporated into a power generation plant or a chemical plant, it is necessary for the plant to be more than partially reliable in terms of stable operation.

Furthermore, the following methods are already known as methods for treating hydrogen sulfide gas.

l) Wet method a) Absorption/desorption method: Absorption with a solvent such as methanol-μ or polyethylene glyco-μ at low temperature and high pressure, and desorption at high temperature and low pressure. There are laws, etc.

b) Absorption oxidation method: A method in which elemental sulfur is produced by absorbing it in an alkaline aqueous solution such as potassium carbonate and partially oxidizing it with air in the presence of a catalyst. Examples include the Takahax method and the Stretford method.

11) Dry method a) A method in which metal oxides such as iron or zinc are adsorbed and removed as sulfides at high temperatures.Other methods include the iron box method.

b) A method of partially oxidizing hydrogen sulfide to form a mixed gas with sulfur dioxide gas and reacting it at high temperature in the presence of a catalyst to form elemental sulfur, such as the Claus method.

The above method 1) aLb) uses coke oven gas (CO
G ) and gas refining in the oil refining process, but it is generally used for gas cooling, dust removal, and contaminating impurities (terμ, naphthalene, halogen, NH, ! (C'N
, CO8, etc.), and to prevent contamination and deterioration of the absorption liquid, the pretreatment equipment is very complicated, and as already mentioned, it is disadvantageous in terms of thermoeconomics because it cools the gas. There is also the issue of wastewater treatment.

The dry method (11) is an advantageous method for processing gasification product gas. However, although the Claus method (b) is widely used in oil refining processes, it is generally applied to high concentration gases of several tens of tons or more, and in the normal Claus method, hydrogen sulfide and sulfur dioxide gas are added to the treated gas due to reaction equilibrium. Since it contains a small amount, further treatment with this tea gas is required, making it difficult to apply it directly. Method a) is an advantageous method for processing high-temperature gasification product gas, but there are problems with powdering and deterioration when reusing the adsorbent, and the need for high-temperature dry processing is also low. Until now, there are almost no full-scale practical devices that regenerate and recycle agents.

(Problems to be Solved by the Invention) In response to the above-mentioned needs regarding processing methods for gasified product gas, the present inventors have conducted research on the development of dry adsorbents and reduction catalysts and the optimization of processing processes. The purpose of this study is to provide the most practically advantageous method for removing hydrogen sulfide from reducing gases.

(Means for Solving the Problems) That is, the present invention adsorbs and removes sulfur compounds contained in high-temperature reducing gas obtained by pressurized gasification of coal, heavy oil, etc. as sulfides using an adsorbent, In a method in which the adsorbent is roasted with air and/or oxygen to regenerate the adsorbent, at the same time a regenerated gas containing concentrated sulfur dioxide gas is obtained, and then the regenerated gas is treated by a wet desulfurization method, the regenerated This method of purifying high-temperature reducing gas is characterized by expanding gas through a gas expander and using the resulting power to pressurize air for roasting through a compressor and a depressor coaxial with the gas expander.

An embodiment of the method of the present invention is shown in FIG.

The method of the present invention will be explained in detail with reference to FIG.

In FIG. 1, coal 1 has a small amount of air or oxygen 2,
It is partially combusted and gasified in the gasifier 3, and a gasified gas 4 containing H3 and Co as main components is obtained. This is used as a substitute for petroleum or natural gas in combined gas turbines, city gas, etc., or as a synthetic raw material for methanol, ammonia, or petrochemicals. This gasification gas 4 varies depending on the type of coal and gasification conditions, but is from several 10 to several 1
000 ppm of H, 8, C'O8, NH, dust, and trace amounts of HF and HCt.
The pressure varies depending on the type of gasifier 3, but it ranges from normal pressure to 25
It is ata.

Therefore, in the method of the present invention, the coarse dust 6 is first removed using a simple dust removal device 5 such as a cyclone, and then when a fixed bed type adsorption/regeneration reactor type as shown in Fig. 1 is used, Further, fine dust 8 is removed by a precision dust removal device 7 such as a Goufnyow bed type, and the coal gasified gas 9 containing no dust is supplied to an adsorption and regeneration reactor 10. Fs in the adsorption and regeneration reactor 10.

Metal oxides such as Zn, Mo, Mn, Cu, and W are used as adsorbents to react with H and B at 250 to 500°C, and are adsorbed and removed as sulfides. The reaction formula for Fe at this time is as follows.

5Fe20B + H2-+ 2F8! 04+H
I 03H2B + Fe3O4+ Hl 43Fe8
+4H! 0HCN + H,O→NH,+GO CO8+ H,S→Co2+H,S In this way, in the adsorption and regeneration reactor 10, the impurity HCN
−? Part of CO8 also reacts and is removed to produce purified gas 11
get.

The reaction temperature is 250 to 500°C, and the gas superficial velocity (fsu flow rate Nm''/h adsorbent capacity 1rLl) is 1000 to 20.0001/h, although it varies depending on the type and particle size of the adsorbent. More than 90% of the H and S contained therein are removed.

Although the type of adsorption/regeneration reactor 10 is shown in FIG. 1 as a fixed bed type, a fluidized bed, moving bed or pneumatic conveyance type is also applicable.

The adsorption and regeneration reactors 10 have the same structure and are filled with the same amount of the above-mentioned adsorbent, but in each reactor, the above-mentioned adsorption reaction and air or/and oxygen 17 as shown in the following formula are carried out.
The regeneration of the adsorbent by the torrefaction reaction caused by the supply of gas proceeds sequentially by switching the gas flow path.

4FeS + 702 →2Fe203 + 480
24Fe304 + OH→6Fez03 As the adsorption reaction described above progresses, the metal oxide in the adsorbent changes to sulfide and is no longer adsorbed, and the supply of coal gasification gas 9 is stopped.
Air or/and oxygen 17 for regeneration reaction is supplied to the compressor 1
6 and is supplied to the reactor 10 under pressure. The regeneration reaction temperature mentioned above is 250 to 750°C, and most of the adsorbed S is dissipated as sulfur dioxide gas, but due to the heat of the regeneration reaction, the log gas 12 from the reactor 10 becomes quite high temperature and is recycled for use in the regeneration reaction. In order to do this, the gas cooler 13 must be used to lower the temperature to a point where the blower 14 can be used. A part of the gas that has passed through the blower 14 is circulated and used for the regeneration reaction, and the regeneration gas 15 is led to the downstream wet desulfurization device 18 through the gas expander 20. Here, the shafts of the compressor 16 and the gas expander 20 are interlocked, and by providing power to the compressor 16 when the regenerated gas 15 is expanded in the gas expander 20, it is possible to significantly reduce the compressor power.

An example of power recovery from regeneration gas is shown below.

1. Gas expander specifications (1) Inlet gas condition Gas amount: 10,59 oklI/h (7,2y aN
m”/b) Gas composition: Vol.
, α03)! , 0 1.51 Nz a艮34 0, a, 45 so, 12.67 100.00 Gas pressure crab 24 kg7am” G Gas temperature near 00℃ (2) Outlet gas condition Gas pressure crab l O5kg/cfIIG (3) Gas expander specifications Axial crab 1.180 kW Discharge temperature: 285℃ Rotation speed: 14.25 Orpm 2 Air compressor specifications (1) Inlet air conditions Air amount: 1o19ok!g/h (796oNm'/h
) Composition: v01 ChiCo, 0.03 H,0148 N2 77.95 0, 2α66 10 α00 Temperature: 15℃ (2) Outlet air condition Pneumatic crab 24.5 kg/cIn2G (3) Air compressor specifications axial movement Crab 1.600 kW Discharge temperature: 240°C Rotation speed: 14.25 Orpm In the wet desulfurization equipment 18, sulfur dioxide gas is converted into μsium sulfate or magnesium sulfate by adding a desulfurizing agent such as lime or magnesium sulfate using an existing desulfurization method. Obtained as recovered material 19.

As described above, the present invention is a method for removing sulfur compounds contained in high-temperature reducing gas obtained by gasification of coal, heavy oil, etc. by adsorption and desorption recycling μ. This is a very useful method in practice, in which the gas is expanded through a panda and the power is used for external pressure of air or oxygen for desorption through a coaxial compressor.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the flow of one embodiment of the present invention for a deaf person. Sub-agents 1) Meifuku agent Ryo Hagiwara - My agent Atsuo Anzai

Claims (1)

[Claims] Sulfur compounds contained in high-temperature reducing gas obtained by pressurized gasification of coal or heavy oil are adsorbed and removed as sulfides using an adsorbent, and the adsorbent is roasted with air and/or oxygen. In this method, the regenerating gas containing concentrated sulfur dioxide gas is obtained at the same time as regenerating the adsorbent, and then the regenerating gas is treated by a wet desulfurization method, in which the regenerating gas is expanded through a gas expander to generate its power. A method for purifying high-temperature reducing gas, characterized in that air for roasting, etc. is pressurized through a compressor coaxial with the gas expander.