JPH0841467A - Coal gasification plant product gas purification method - Google Patents

Abstract

(57) [Summary] [Objective] To provide a gas purification system related to dedusting and desulfurization of a spouted bed coal gasification plant. [Structure] In a method for purifying gas produced in a spouted bed coal gas reactor, a packed tower or a moving bed for recovering vitrified solids from the lower part of the reactor and filling the solids with an accurate particle size distribution Establishing a dedusting system with a cyclone installed between spouted bed reactors, and performing dedusting and desulfurization by spraying atomized desulfurizing agent from the reactor to the appropriate temperature range of the packed bed and moving bed. Is characterized by. [Effect] The present invention is less expensive than the conventional ceramic filter, and the dust removal performance can be adjusted. Further, since the desulfurization reaction time can be adjusted, high desulfurization performance can be obtained.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a gas refining method and a gas refining method for gasifying coal, and particularly to a gas refining method for a generated gas suitable for a spouted bed coal gasification plant for extracting ash contained in coal in a molten state. To do.

[0002]

2. Description of the Related Art At present, the mainstream of thermal power generation boilers is a method in which coal is burned, high temperature gas is heat-exchanged, and a steam turbine is used to convert energy into electric power. A combined power generation plant that gasifies coal to use as fuel gas is being developed for the purpose of improving energy conversion efficiency. The produced gas obtained by gasifying coal in this plant contains dust as solid fine particles, a sulfur compound, a halogen compound, and the like. High-efficiency gas refining technology is required from the development of multipurpose applications other than the combined power generation plant for generated gas.

Although a spouted bed or fluidized bed system has been developed for this coal gasification reactor, the present invention relates to a gas purification method for the product gas of the former spouted bed coal gasification reactor.

[0004]

In order to use the gas produced by the gasification of coal for multiple purposes, it is necessary to purify the produced gas according to the purpose. The present invention is a gas refining method for industrial or combined power generation fuel gas produced by coal gasification, and in particular, has a system configuration capable of achieving high-efficiency dedusting and desulfurization at the same time. The above-mentioned ceramic filter, which has high dust collection performance for the purpose of high-efficiency dust removal, is becoming the mainstream. However, in order to use it under high temperature and high pressure, cracks in the ceramic filter,
There is a risk of damage and there is a problem with reliability during long-term operation, so improvement is urgently needed. If a part of the ceramic filter applied to the combined cycle power plant is damaged itself, the turbine blade may be worn and greatly damaged, which may cause an emergency situation in which power generation is stopped.

It has been confirmed that the dust-removing performance of each cyclone of a small-diameter multi-cyclone efficiently removes large dust particles of 3 to 5 μm or more that affect the wear of turbine blades. When multiple cyclones are installed in parallel, a slight pressure difference occurs between the cyclones, and the dust separated by the cyclones may flow in from the bottom of other cyclones, which reduces the dust collection performance. There is concern that it may cause turbine blade wear problems. In addition, since the cyclone of each multi-cyclone has a small tube diameter, there is a problem that clogging occurs at the part for separating dust and so that the original function of the cyclone itself is not fulfilled.

In the spouted bed coal gasification reactor, most of the soot and dust are extracted from the lower part of the reactor in a molten state,
The amount of soot and dust that accompanies the produced gas can be made smaller than that in the fluidized bed reactor, but the soot and dust that accompanies the produced gas has a large particle size of 3 μm or less, which is difficult to collect. In order to collect these submicron particles by the conventional electrostatic precipitating method, the amount of electric charge received by the particles of soot and dust itself is small and the moving speed of the particles due to the electric field is slow, which leads to a drawback that the apparatus volume becomes large. Further, since fine limestone added as a desulfurizing agent has high electric resistance, there is a problem that the reverse ionization phenomenon occurs and the dust collection performance is deteriorated. In addition, the bag filter method has a problem that when the particle size of dust is small, the filter is clogged quickly and it is necessary to frequently remove the filter, which shortens the life of the filter.

The present invention has been made in view of the above circumstances, and is a jet-bed gasification power generation system for removing solid fine particles from a gas produced from a jet-bed coal gasification reactor with high efficiency and desulfurization at the same time. It is to provide a gas refining method for a plant.

[0008]

The present invention is directed to high temperature, high pressure,
In the method for refining gas produced from a coal gasification reactor in a reducing atmosphere, limestone, slaked lime, quick lime, barium oxide,
After spraying one of the compounds selected from barium hydroxide, barium carbonate, magnesium oxide, magnesium hydroxide, cement clinker, cement or a mixture thereof as a desulfurizing agent into the produced gas system having a gas temperature of around 1000 ° C, Introduced into a cyclone to be installed in the subsequent flow, further to form a slag packed bed filled with slag extracted from the lower part of the spouted bed coal gasification reactor to be installed in the downstream of the cyclone, the cyclone outlet gas It is characterized by conducting dust removal and desulfurization by introducing it to a slag packed bed.

In addition, a plurality of layers are provided in parallel with the slag filling layer in the flow of the generated gas, and the ventilation loss of the slag filling portion in which the generated gas is flowing or the stacking thickness of the solid fine particles detects a set value. Then, the slag packed bed in which the generated gas is introduced is characterized in that dedusting and desulfurization are performed by switching the flow path of the generated gas to the constituent part of the packed bed filled with new slag.

Further, a moving bed of the slag extracted from the spouted bed coal gasification reactor is formed in the wake of the cyclone to remove dust and desulfurize the produced gas.

Further, the slag and the solid fine particles extracted from the slag packed layer and the slag moving layer are classified, and a part of the slag is recirculated to perform dust removal and desulfurization.

Further, the solid fine particles are burned under an oxygen excess condition to oxidize the sulfur compounds in the solid fine particles to generate sulfur dioxide gas, which is then brought into contact with a limestone slurry containing sulfur dioxide, and calcium sulfate is mixed with sulfur oxides. It is characterized in that dust and desulfurization are performed by spraying a part of the solid fine particles that have been oxidized and regenerated to the gas flow path in the appropriate gas temperature range.

The solid fine particles are burned under an oxygen excess condition to oxidize the sulfur compounds in the solid fine particles to generate sulfur dioxide gas, and the solid fine particles from which the sulfur dioxide gas has been removed are suspended in water by a slurry. It is characterized in that the sulfur oxide is absorbed.

According to the present invention, in order to achieve high-efficiency dedusting and desulfurization at the same time, a slag packed layer is formed by using slag extracted from a spouted bed coal gasification reactor as a high-efficiency dedusting filter agent, and Ca, Mg Of the desulfurization reaction of the fine-particle absorbent of the system
With a system configuration in which solid particles containing a desulfurizing agent are collected by spraying in a temperature region near 00 ° C. in a slag packed bed, the residence time required for the desulfurization reaction can be lengthened and the desulfurization performance can be improved.
By adjusting the slag stacking height and the solid fine particle stacking height of the present invention, the filter function can be changed, so that the dust removal performance can be maintained at a predetermined value.

[0015]

The high-efficiency dedusting and desulfurization action of the spouted bed coal gasification power plant of the present invention will be described below. The spouted bed gasification reactor has a function of simultaneously supplying fine coal and oxygen (oxygen gas or air) to burn a part of coal and at the same time thermally decomposing other coal to generate fuel gas and melt ash. Ordinary coal contains 8 to 15% of ash, and the spouted bed coal gasification reactor has 1450 to 100% of this ash.
Melt at a temperature of 1600 ° C. and withdraw from the spouted bed coal gasification reactor. The main components of coal ash itself are silica and alumina, and stable glassy solids can be collected when melted. This solid matter is called slag, and since it is reduced in volume from ash content, it is easy to handle and it is usually targeted for disposal. The present invention is to construct a disposable high-performance dust removal system by using a glass-like slag of this ash crushed to an appropriate particle size distribution of about 1 to 5 mm as a filter agent for dust removal. is there. That is, it is a gas purification method in which solid fine particles contained in the produced gas are collected by a slag packed bed or a slag moving bed using this slag as a filtering agent. FIG. 4 shows a state in which the dust collecting function is an enlarged view of the portion surrounded by the dotted line of the packed bed 39 in FIG. The state of lamination of solid fine particles, desulfurizing agent, and slag particles is shown. Therefore, when dust or desulfurizing agent particles are collected in the slag packed bed and the respective stack heights increase, the dust collection performance can be improved in response to ventilation loss. Structurally, the slag (which may be a glassy solid) 6 is supported by a mesh wire netting or a perforated plate 102 with holes, dust 101 and desulfurizing agent particles 100 are stacked, and the stack height is high. The dust collection performance gradually increases as it becomes. The dust collection efficiency is affected by changes in the particle size of the filtering agent, the stacking thickness, the gas flow rate, and the stacking thickness of the solid particles depending on the elapsed operating time.

In addition to the high dedusting function, another function of the present invention is to perform desulfurization by spraying an absorbent for desulfurization into a reactor or a gas flow passage to perform desulfurization and prolong the residence time in a slag packed bed to carry out desulfurization reaction. It is a point to raise. Each absorbent needs optimum reaction temperature conditions and residence time. In the case of typical limestone, the CaO reaction actively occurs at around 800 ° C. Judging from many experimental results, the reaction activity of CaO is 100.
The highest temperature is around 0 to 1100 ° C. Therefore, when using limestone as a desulfurizing agent, it is necessary to select the optimum temperature condition in the gas flow path from the reactor and spray. Even with the same Ca-based absorbent, in the case of slaked lime, the CaO formation reaction occurs from around 400 ° C. The desulfurization reaction is a reaction between CaO and hydrogen sulfide produced by thermal decomposition of coal, and the reaction product is mainly composed of CaS. The reaction with CaO at this time is a surface reaction and Ca
Determined by particle size of O and residence time. The residence time in the gas flow path from the spouted bed gasification reactor to the gas turbine is several seconds, which is a sufficient time for the desulfurization reaction. In the present invention, unreacted CaO, reaction product CaO,
By collecting solid fine particles such as dust, unreacted C
By increasing the reaction rate of aO and adjusting the thickness of the solid fine particles stacked in the packed bed, it is possible to achieve the above-described function of performing highly efficient dedusting, which is a fuel for a spouted bed coal gasification power plant. Further, as a gas, a gas purification method of a multipurpose product gas can be provided.

FIG. 2 shows an example of a spouted bed coal gasification reactor and gas purification system in which the present invention may be used. The spouted bed coal gasification reactor 1 is characterized by a system in which finely pulverized coal 4 is simultaneously fed with air or oxygen gas 5 into the reactor to burn a part of the coal to thermally decompose the coal and melt ash. Is. At this time, in the lower part of the spouted bed coal gasifier 1, there is a function of melting the ash contained in coal at a temperature of 1500 to 1600 ° C. to reduce the volume of the ash, and the molten ash (glassy solid) 6 is Solid matter (slag) is extracted from the spouted bed coal gasification reactor 1. The molten ash content 6 extracted from the spouted bed coal gasification reactor 1 is cooled at the time of extraction and is recovered as vitrified stable slag.
Usually, this slag is a stable substance and is targeted for dumping.

The produced gas 17 from the spouted bed coal gasification reactor 1 has a temperature near 800 to 1000 ° C. and is sent to a heat exchanger (which can be, for example, a cooler) 7 4
It is cooled to 00 ° C. and sent to the dust remover 9. Here, the coal gasification residue and the desulfurization agent 2 are simultaneously collected. The collected solid fine particles are sent to the desulfurization device 11, and the purified product gas is the fuel gas 13 for the fuel cell, the fuel gas 14 of the combined power generation plant to which the present invention is applied, and the raw material of the synthesis gas and the hydrogen production plant 15. Used as a gas for multiple purposes.

Specifically, the produced gas contains ash and unburned carbon as solid fine particles and sulfur compounds and halogen compounds as harmful gases, and various gas purification methods for removing these have been reported. The produced gas contains ash and solid particles of unburned carbon. In order to separate and remove this, high temperature bag filters, ceramic candle filters, multi cyclones, granular beds, electrostatic precipitators, etc. have been reported. Although the dust removal performance varies depending on the dust removal method, the dust concentration after the treatment can be reduced to about 5 to 30 mg per cubic meter.

The produced gas contains sulfur compounds and halogen compounds in addition to dust. As an absorbent or an adsorbent for removing these, Fe ₂ O ₃ , Fe ₂ O ₃ -TiO ₂ , Fe
₂ O ₃ -alumina, Zn-Fe, Zn-Ti, Co-Ti
O ₂ etc. have been reported. Further, as a method for desulfurization in the reactor, a method of spraying a Ca, Mg-based atomized product into the reactor has been studied. In addition, NaHCO ₃ was added in parallel with the desulfurizing agent to remove halogen compounds,
A method of removing it as a compound of 1NaF has been reported. Further, when the generated gas is used as a fuel gas for gas turbine combined power generation, NH ₃ gas in the generated gas is oxidized to nitrogen oxides in the gas turbine, so a removal method using a Ni-based catalyst or a zeolite adsorbent is being studied. .

[0021]

【Example】

(Example 1) FIG. 1 shows an example of a typical gas refining method of a spouted bed coal gasification plant of the present invention. The spouted bed coal gasification reactor 1 is supplied with coal (fine coal) 4 and oxygen gas or air 5. Part of the supplied coal 4 is burned and supplied to the thermal decomposition heat source of coal and the melting heat source of ash. The melted ash 6 is extracted to the outside of the coal gasification reactor 1. The molten ash is collected as slag after cooling. The produced gas 3 produced by the thermal decomposition of coal passes through the flow path 17, passes through the conventional gas cooler 7 shown in FIG. 2 and is cooled to an appropriate temperature and then introduced into the cyclone 30 to partially solidify solid fine particles in the produced gas. The fine particles are roughly taken at a rate of 50 to 70%, and the collected solid fine particles 38 are taken out of the system. Product gas 31
Is introduced into the filling layer 39 filled with the glassy solid material 37. The solid fine particles 36 in the produced gas are collected by the glass-like solid material 37 in the packed bed 39. The packed bed a detects the ventilation loss or the layer thickness of the solid fine particles 36, and when the value exceeds a predetermined value, the generated gas 31 flowing in the packed bed a is circulated to the packed bed b by a switching valve 32. The product gas from which solid particulates have been removed is fed from stream 35 to the gas turbine. The filling layer a is made by extracting solid fine particles and glassy solid matter and newly filling them with glassy solid matter.

In the present invention, in order to improve the dust collection performance and the desulfurization performance, limestone is sprayed from the spouted bed coal gasification reactor between the gas channels of the packed bed group (dotted line portion) at a gas temperature of around 1000 ° C. This causes desulfurization. The quick calcification reaction of the formula (1) actively progresses at a temperature of 800 ° C. or higher, and the optimum temperature is 1000 to 1100 ° C. When the temperature becomes too high, the CaO surface causes sintering and the desulfurization reaction of the formula (2). Is reduced.

CaCO ₃ → CaO + CO ₂ (1) CaO + H ₂ S → CaS + H ₂ O (2) When Ca (OH) ₂ is used as the absorbent, the quick calcification reaction is 400 ° C. as shown in the formula (3). Since it occurs from the vicinity, it can be sprayed to the gas flow system outside the system of the spouted bed reactor.

Ca (OH) ₂ → CaO + H ₂ O (3) (Example 2) FIG. 3 shows an example of the gas purification method of the spouted bed coal gasification plant of the present invention. The embodiment of FIG. 3 is basically the same up to the flow 31 of FIG. 1, and is an application example of the moving bed 43 instead of the packed bed 39 of FIG. To the moving bed 45, the glassy solid obtained by cooling the glassy solid (molten ash) 6 extracted from the lower portion of the spouted bed coal gasification reactor 1 is supplied to the hopper 41. The vitreous solids 6 in the hopper 41 are fed from the stream 42 to the moving bed 43. Glassy moving layer 4
3 is slowly moved to the lower part by its own weight and is stored in the hopper 47 from the flow 46 and sent to the classifier 48 to separate the collected ash, unburned carbon, desulfurizing agent and glassy solid 49. A part of the glassy solid material 49 can be used in the hopper 41, but most of the solid material 49 is intended for disposal. On the other hand, most of the classified ash, unburned carbon, and desulfurization agent contain sulfur compounds in the form of CaS, and therefore these are treated. A typical example of the treatment method is that when CaS is burned in an oxygen-excessive state, sulfur oxides are generated. Therefore, by contacting this with a suspension of limestone, stable gypsum can be recovered. The combustion of CaS and the absorption reaction with the suspension of limestone occur as follows.

CaS + 3 / 2O ₂ → CaO + SO ₂ (4) C + O ₂ → CO ₂ (5) CaCO ₃ → CaO + CO ₂ (6) CaO + 1 / 2O ₂ + SO ₂ → CaSO ₄ (7) Oxygen excess of solid fine particles Combustion in the state is mainly (4),
The reactions (5) and (6) occur. The reaction of the formula (5) is unburned carbon collected as solid fine particles, and the reaction of the formula (6) is C generated by thermal decomposition when limestone is used as a desulfurizing agent.
CaO _{3 in} which aO reacts with CO ₂ in the produced gas becomes CaO again in the combustion process. When the SO ₂ gas generated in (4) is brought into contact with a suspension of limestone accompanied with air, the reaction of the formula (7) occurs and gypsum can be recovered. Therefore, CaO generated by the formula (4) becomes slaked lime (Ca (OH) ₂ ) as a desulfurizing agent by blowing it into a high-temperature atmosphere, and when suspended in water by digestion reaction. This slaked lime (Ca (OH) ₂ ) is once fixed as CaSO ₃ when the liquid suspended in water is brought into contact with the gas of formula (4), but it is recovered as CaSO _{4 when} it is oxidized in the liquid phase. it can.
CaSO ₄ is recovered as dihydrate gypsum in the liquid phase oxidation reaction.

(Example 3) The desulfurizing agent is limestone, slaked lime, quick lime, barium oxide, barium hydroxide, barium carbonate,
Magnesium oxide, magnesium hydroxide, cement clinker, cement, etc. can be used. Each desulfurizing agent is thermally decomposed into CaO, BaO, MgO and reacts with H ₂ S in the produced gas to produce a sulfur compound of CaS, BaS, MgS. The main components of cement clinker and cement are CaO, SiO ₂ , and Al ₂ O ₃ , and the desulfurization reaction with H ₂ S is the same as that of the above-mentioned oxide.

Of these, inexpensive limestone and slaked ash are often used, and the relationship between the partial pressures of CO ₂ and H ₂ O in the produced gas and the decomposition temperature is estimated from the free energy relationship in FIG.
When the CO ₂ concentration in the produced gas is 10%, the limestone decomposition temperature begins to be actively decomposed from around 770 ° C, and when the moisture in the produced gas is 10%, the decomposition reaction of slaked lime proceeds from around 398 ° C. . When the concentrations of CO ₂ and H ₂ O are low, the decomposition start temperature of each can be lowered. Therefore, in order to use fine limestone as a desulfurizing agent, CaO and desulfurization reaction proceed by spraying fine limestone in the gas temperature range of the spouted bed coal gasification reactor in the range of 1000 to 1100 ° C. When slaked lime is used as the desulfurizing agent, the temperature of the produced gas is 500 to 600 ° C.
Can be sprayed on.

(Example 4) As a result of desulfurization experiment at a temperature of 1000 ° C. with a simulated gas containing 700 ppm of hydrogen sulfide using limestone having an average particle diameter of 10 μm as a desulfurizing agent, flight residence time of 10 μm in average particle diameter and CaO formation and CaS formation were confirmed. As a result of examining the simultaneous reaction, in the case of Ca / S = 2, 78% at a residence time of 1.2 seconds,
It was 92% at 2.2 seconds and 94.5% at residence time of 3 seconds. When the Ca / S was increased to 2.5, the desulfurization rate dramatically increased, and it was 95% at the residence time of 2.2 seconds. Further, the desulfurization rate has a great influence on the spray rate of the desulfurizing agent, and the desulfurization rate increases as the difference between the spray rates of the exhaust gas and the desulfurizing agent increases.

(Embodiment 5) Limestone, slaked lime, quicklime, barium oxide, barium hydroxide, barium carbonate, magnesium oxide, magnesium hydroxide, cement clinker and cement, each having a simulated gas containing 700 ppm of hydrogen sulfide at a temperature of 1000 ° C., Ca The desulfurization rate was investigated when / S was 2. When the reaction rate of CaO and SO _{2 in} limestone is 1, slaked lime, quick lime, barium oxide, barium hydroxide, barium carbonate, magnesium oxide, magnesium hydroxide, cement clinker, and cement are respectively
1.4, 1.3, 1.2, 1.35, 1.1, 1.2, 1.25,
They were 1.35 and 1.12. Cement and cement clinker were evaluated from the content of CaO by elemental analysis.

(Embodiment 6) Further, the dust collecting performance of the packed bed and the moving bed is proportional to the particle size of the glassy solid of the present invention, the layer thickness, the exhaust gas flow rate, and the dust stacking thickness. The average particle size of the glassy solids packed in the packed bed and the moving bed is 2500 μm.
In the case of, the ventilation loss when laminated to 0.1 m is
It is 470 to 550 mmaq in the moving bed. Ventilation loss increased by 250 mm when 12 mm of solid particles of dust were laminated on this. The dust collection performance at this time was 97% when the inlet dust concentration was 1.1 g per cubic meter. Dust removal rate of moving bed is lower than packed bed 94.5%
Met. If the particle size distribution of glassy solids is the same, the dust removal rate affects the dust stack height and the exhaust gas flow velocity, and when the stack thickness is 5 mm, it is 91.4% in the case of the packed bed, and increases to 20 mm. The dust removal rate was 97.4%.

In the gas refining method according to the method of the present invention described above, a desulfurization absorbent is atomized to an appropriate temperature range in a gas refining method system in which a spouted bed coal gasification reactor, a cyclone, a packed bed or a moving bed are combined. By spraying in the state, it is possible to improve desulfurization and dust removal performance.

[0032]

The present invention is less expensive than the conventional ceramic filter, and the dust removal performance can be adjusted. Further, since the desulfurization reaction time can be adjusted, high desulfurization performance can be obtained. Packed column, the solid particles are collected in transfer layer can be treated stabilized regardless of the glassy solid and was separated spouted bed reactor of the present invention, solid particulate removing sulfur oxides SO ₂ Can be reused as an absorbent.

[Brief description of drawings]

FIG. 1 is a gas purification system for a typical spouted bed coal gasification plant of the present invention.

FIG. 2 is an example of a gas purification system for a spouted bed coal gasification plant in which the present invention can be used.

FIG. 3 is a gas purification system combining the moving bed of the present invention and a cyclone.

FIG. 4 is a diagram showing the principle of a glass solid dust and a desulfurizing agent filter action.

FIG. 5: Decomposition temperature of representative desulfurizing agents.

[Explanation of symbols]

1 ... Spouted bed coal gasification reactor, 2 ... Desulfurizing agent, 4 ... Coal,
5 ... Air or oxygen gas, 6 ... Glassy solid matter, 7 ...
Cooler, 9 ... Dust remover, 10, 35, 44 ... Generated gas, 3
0 ... Cyclone, 32 ... Switching valve, 38 ... Solid particulates, 39 ... Packed bed, 43 ... Moving bed, 47 ... Hopper, 4
8 ... Classifier.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C10J 3/54 J 3/72 F C10K 1/28 1/30 (72) Inventor Hiroshi Miyadera Ibaraki Prefecture Hitachi City Omika-cho 7-1-1, Hitachi Ltd. Hitachi Research Laboratory

Claims (6)

[Claims] 1. A method for refining gas produced from a coal gasification reactor in a high temperature, high pressure, reducing atmosphere, wherein limestone, slaked lime, quick lime, barium oxide, barium hydroxide, barium carbonate, magnesium oxide, magnesium hydroxide, cement. The gas temperature is 1000 ° C using either a clinker or cement compound or a mixture thereof as a desulfurizing agent.
After spraying the generated gas system in the vicinity, it is introduced into a cyclone installed in the subsequent stream, and further, slag filling filled with slag extracted from the lower part of the spouted bed coal gasification reactor installed in the downstream of the cyclone. A method for purifying a gas produced in a coal gasification plant, which comprises forming a layer and introducing the cyclone outlet gas to the slag packed bed to perform dedusting and desulfurization. 2. The slag packing layer according to claim 1 is installed in parallel with the flow of the generated gas to set a plurality of layers, and the ventilation loss of the slag filling section in which the generated gas is flowing or the laminated thickness of solid fine particles is set. When the value of is detected, the slag packed bed introducing the generated gas is characterized by performing dedusting and desulfurization by switching the flow path of the generated gas to the constituent part of the packed bed filled with the new slag. Method for refining gas produced from coal gasification plant. 3. A moving bed of slag extracted from a spouted bed coal gasification reactor is formed in the wake of the cyclone according to claim 1 to remove dust and desulfurize the produced gas. Method for refining gas produced by coal gasification plant. 4. The slag packed bed and the slag extracted from the slag moving bed according to claims 1, 2, and 3 are classified, and a part of the slag is recirculated to perform dedusting and desulfurization. Method for refining gas produced by coal gasification plant. 5. The solid fine particles described in claim 4 are burned under an oxygen excess condition to oxidize the sulfur compounds in the solid fine particles to generate sulfur dioxide gas, which is then brought into contact with a limestone slurry containing this sulfur dioxide and calcium sulfate. A coal gasification plant, characterized in that sulfur oxides are oxidised, and a part of the regenerated solid fine particles is sprayed into the gas flow path in the gas temperature range described in claim 1 to carry out dedusting and desulfurization. Product gas purification method. 6. The solid fine particles according to claim 4 are burned under an oxygen excess condition to oxidize a sulfur compound in the solid fine particles to generate sulfur dioxide gas, and the solid fine particles from which the sulfur dioxide gas has been removed are suspended in water. A method for refining a gas produced from a coal gasification plant, characterized in that the sulfur oxide is absorbed by a turbid slurry.