阅读说明：本技术 煤炭高效催化气化系统及方法 (High-efficiency catalytic gasification system and method for coal ) 是由 李克忠 武恒 毛燕东 芦涛 刘雷 于 2020-06-02 设计创作，主要内容包括：本公开涉及煤气化技术领域,提供了一种煤炭高效催化气化系统及方法。包括灰浆气化单元、催化气化单元及催化热解单元；催化热解单元用于通入原料煤和催化气化单元生成的高温粗煤气,原料煤和高温粗煤气发生热解反应和甲烷化反应生成煤焦、粗煤气、焦油及煤灰；灰浆气化单元用于通入氧气、水、催化气化单元生成的炉灰和催化热解单元生成的煤灰,氧气、水、炉灰和煤灰发生燃烧反应、煤气化反应及水煤气变换反应生成高温湿煤气和灰渣；催化气化单元用于通入灰浆气化单元生成的高温湿煤气和催化热解单元生成的煤焦,高温湿煤气和煤焦发生煤气化反应、水煤气变换反应及甲烷化反应生成高温粗煤气和炉灰；实现高碳转化率,提高焦油和甲烷产率。(The disclosure relates to the technical field of coal gasification, and provides a high-efficiency catalytic gasification system and method for coal. Comprises a mortar gasification unit, a catalytic gasification unit and a catalytic pyrolysis unit; the catalytic pyrolysis unit is used for introducing raw material coal and high-temperature raw gas generated by the catalytic gasification unit, and the raw material coal and the high-temperature raw gas are subjected to pyrolysis reaction and methanation reaction to generate coal coke, raw gas, tar and coal ash; the mortar gasification unit is used for introducing oxygen, water, furnace dust generated by the catalytic gasification unit and coal ash generated by the catalytic pyrolysis unit, and the oxygen, the water, the furnace dust and the coal ash generate combustion reaction, coal gasification reaction and water gas shift reaction to generate high-temperature wet coal gas and ash slag; the catalytic gasification unit is used for introducing high-temperature wet coal gas generated by the mortar gasification unit and coal coke generated by the catalytic pyrolysis unit, and the high-temperature wet coal gas and the coal coke are subjected to coal gasification reaction, water gas shift reaction and methanation reaction to generate high-temperature raw coal gas and furnace dust; high carbon conversion rate is realized, and the yield of tar and methane is improved.)

1. A high-efficiency catalytic coal gasification system is characterized by comprising a mortar gasification unit (1), a catalytic gasification unit (2) and a catalytic pyrolysis unit (3);

the catalytic pyrolysis unit (3) is used for introducing raw material coal and the high-temperature raw gas generated by the catalytic gasification unit (2), and the raw material coal and the high-temperature raw gas are subjected to pyrolysis reaction and methanation reaction to generate coal coke, raw gas, tar and coal ash;

the mortar gasification unit (1) is used for introducing oxygen, water, furnace ash generated by the catalytic gasification unit (2) and coal ash generated by the catalytic pyrolysis unit (3), and the oxygen, the water, the furnace ash and the coal ash are subjected to combustion reaction, coal gasification reaction and water gas shift reaction to generate high-temperature wet coal gas and ash;

the catalytic gasification unit (2) is used for introducing high-temperature wet coal gas generated by the mortar gasification unit (1) and coal tar generated by the catalytic pyrolysis unit (3), and the high-temperature wet coal gas and the coal tar are subjected to coal gasification reaction, water gas shift reaction and methanation reaction to generate high-temperature raw coal gas and furnace dust;

the reaction temperatures of the mortar gasification unit (1), the catalytic gasification unit (2) and the catalytic pyrolysis unit (3) are sequentially decreased progressively.

2. The coal high-efficiency catalytic gasification system according to claim 1, further comprising a separation unit (4) and a mortar preparation unit (5), wherein the separation unit (4) is used for separating crude gas, tar and coal ash generated by the catalytic pyrolysis unit (3); the mortar preparation unit (5) is used for preparing mortar from the coal ash separated by the separation unit (4) and the furnace ash generated by the catalytic gasification unit (2), and the prepared mortar is fed into the mortar gasification unit (1).

3. The system for high-efficiency catalytic gasification of coal as claimed in claim 2, further comprising a catalyst recovery unit (6), wherein the catalyst recovery unit (6) is used for recovering the catalyst in the furnace ash generated by the catalytic gasification unit (2) and the coal ash generated by the catalytic pyrolysis unit (3), and the furnace ash and the coal ash recovered by the catalyst are passed into the mortar preparation unit (5).

4. The efficient catalytic coal gasification system according to claim 2, wherein a gas-solid separation unit (7) is arranged between the catalytic pyrolysis unit (3) and the separation unit (4), an inlet of the gas-solid separation unit (7) is connected with the catalytic pyrolysis unit (3), a gas outlet of the gas-solid separation unit (7) is connected with the separation unit (4), and a dust outlet of the gas-solid separation unit (7) is connected with the catalytic gasification unit (2).

5. The system for high-efficiency catalytic gasification of coal as claimed in claim 1, wherein a waste heat boiler unit (8) is arranged between the catalytic gasification unit (2) and the catalytic pyrolysis unit (3), and the waste heat boiler unit (8) is used for heat exchange and temperature reduction of the high-temperature raw gas introduced into the catalytic pyrolysis unit (3) from the catalytic gasification unit (2).

6. The system for high efficiency catalytic gasification of coal according to claim 1, characterized in that the reaction temperature of the mortar gasification unit (1) is 850 to 1300 ℃.

7. The system for high efficiency catalytic gasification of coal according to claim 1, characterized in that the reaction temperature of the catalytic gasification unit (2) is 650 to 800 ℃.

8. The coal high efficiency catalytic gasification system according to claim 1, characterized in that the reaction temperature of the catalytic pyrolysis unit (3) is 400 to 600 ℃.

9. A high-efficiency catalytic gasification method for coal is characterized by comprising the following steps:

firstly, raw material coal and high-temperature crude gas generated by the catalytic gasification unit (2) are introduced into the catalytic pyrolysis unit (3), the raw material coal and the high-temperature crude gas are subjected to pyrolysis reaction to generate coal coke, crude gas, tar and coal ash, wherein the coal coke is introduced into the catalytic gasification unit (2), and the coal ash is introduced into the mortar gasification unit (1);

secondly, introducing oxygen and water into the mortar gasification unit (1), wherein the oxygen, the water, the furnace ash and the coal ash are subjected to combustion reaction, coal gasification reaction and water gas shift reaction to generate high-temperature wet coal gas and ash, and the high-temperature wet coal gas is introduced into the catalytic gasification unit (2);

and step three, performing coal gasification reaction, water gas shift reaction and methanation reaction on the high-temperature wet coal gas and the coal coke in the catalytic gasification unit (2) to generate high-temperature raw coal gas and furnace ash, wherein the furnace ash is introduced into the mortar gasification unit (1) in the step two, and the high-temperature raw coal gas is introduced into the catalytic pyrolysis unit (3) in the step one.

10. The high-efficiency catalytic gasification method according to claim 9, wherein the coke, the crude gas, the tar and the coal ash generated by the catalytic pyrolysis unit (3) are firstly introduced into the gas-solid separation unit (7) for gas-solid separation, and then introduced into the separation unit (4);

the separation unit (4) separates carbon monoxide, hydrogen and methane in the crude gas generated by the catalytic pyrolysis unit (3) to be used as a gas product, separates the generated tar to be used as a tar product, and separates the coal ash to be introduced into the catalyst recovery unit (6);

the furnace ash generated by the catalytic gasification unit (2) and the coal ash separated by the separation unit (4) are firstly introduced into a catalyst recovery unit (6) for catalyst recovery, and then introduced into a mortar preparation unit (5), and the prepared mortar is introduced into a mortar gasification unit (1);

high-temperature raw gas generated by the catalytic gasification unit (2) is firstly introduced into the waste heat boiler unit (8) for heat exchange and temperature reduction, and then is introduced into the catalytic pyrolysis unit (3).

Technical Field

The disclosure relates to the technical field of coal gasification, in particular to a high-efficiency catalytic gasification system and method for coal.

Background

The realization of clean and efficient utilization of coal is a subject of continuous exploration in the energy technology industry. With the technological progress, coal gasification gradually becomes one of the main ways of high-efficiency and clean utilization of coal. The prior coal gasification technology mainly adopts the processes of brown coal gasification of a two-stage furnace, crushed coal pressure gasification, high-pressure fluidized bed gasification, coal water slurry entrained flow bed gasification, pulverized coal entrained flow bed gasification and the like. The gasification temperature and pressure requirements of the coal water slurry entrained flow bed gasification and pulverized coal entrained flow bed gasification processes are relatively high, and synthesis gas (CO and H) is mainly produced₂) When the catalyst is used for synthesizing chemicals, the carbon conversion rate is high, but byproducts such as methane, tar and the like do not exist. The gasification temperature and pressure of the high-pressure fluidized bed gasification process are lower than those of the entrained flow gasification process, and although the coal gas product contains methane, the proportion is relatively low, and the carbon conversion rate is not high. The crushed coal pressure gasification process can produce tar and a certain content of methane products, but the raw materials are mainly lump coal, and the carbon conversion rate is lower than that of the entrained flow bed gasification process. The two-stage furnace lignite gasification process can produce more tar and coal gas with high methane content, but the carbon conversion rate is only 50-60%.

The gasification technology is restricted by raw materials, operation conditions and the like, can not simultaneously meet the technical requirements of high carbon conversion rate, high tar, high methane generation rate and the like, can not realize the development targets of staged conversion and cascade utilization of coal advocated at present, and influences the applicability and the economical efficiency of the gasification technology to a certain extent.

Disclosure of Invention

In order to solve the technical problems or at least partially solve the technical problems, the present disclosure provides a system and a method for high-efficiency catalytic gasification of coal, which achieve high carbon conversion rate and improve tar and methane yield.

The utility model provides a high-efficient catalytic gasification system of coal, including mortar gasification unit, catalytic gasification unit and catalytic pyrolysis unit; the catalytic pyrolysis unit is used for introducing raw material coal and high-temperature raw gas generated by the catalytic gasification unit, and the raw material coal and the high-temperature raw gas are subjected to pyrolysis reaction and methanation reaction to generate coal coke, raw gas, tar and coal ash; the mortar gasification unit is used for introducing oxygen, water, furnace dust generated by the catalytic gasification unit and coal ash generated by the catalytic pyrolysis unit, and the oxygen, the water, the furnace dust and the coal ash generate combustion reaction, coal gasification reaction and water gas shift reaction to generate high-temperature wet coal gas and ash slag; the catalytic gasification unit is used for introducing high-temperature wet coal gas generated by the mortar gasification unit and coal coke generated by the catalytic pyrolysis unit, and the high-temperature wet coal gas and the coal coke are subjected to coal gasification reaction, water gas shift reaction and methanation reaction to generate high-temperature raw coal gas and furnace dust; the reaction temperatures of the mortar gasification unit, the catalytic gasification unit and the catalytic pyrolysis unit are decreased gradually.

Optionally, the system further comprises a separation unit and a mortar preparation unit, wherein the separation unit is used for separating crude gas, tar and coal ash generated by the catalytic pyrolysis unit; the mortar preparation unit is used for preparing mortar from the coal ash separated by the separation unit and the furnace ash generated by the catalytic gasification unit, and the prepared mortar is introduced into the mortar gasification unit.

Optionally, the system further comprises a catalyst recovery unit, wherein the catalyst recovery unit is used for recovering the catalyst in the furnace ash generated by the catalytic gasification unit and the coal ash generated by the catalytic pyrolysis unit, and the furnace ash and the coal ash recovered by the catalyst are introduced into the mortar preparation unit.

Optionally, a gas-solid separation unit is arranged between the catalytic pyrolysis unit and the separation unit, an inlet of the gas-solid separation unit is connected with the catalytic pyrolysis unit, a gas outlet of the gas-solid separation unit is connected with the separation unit, and a dust outlet of the gas-solid separation unit is connected with the catalytic gasification unit.

Optionally, a waste heat boiler unit is arranged between the catalytic gasification unit and the catalytic pyrolysis unit, and the waste heat boiler unit is used for exchanging heat and cooling the high-temperature raw gas introduced into the catalytic pyrolysis unit by the catalytic gasification unit.

Alternatively, the reaction temperature of the mortar gasification unit is 850 to 1300 ℃.

Optionally, the reaction temperature of the catalytic gasification unit is 650 to 800 ℃.

Optionally, the reaction temperature of the catalytic pyrolysis unit is 400 to 600 ℃.

The invention also provides a high-efficiency catalytic gasification method of coal, which comprises the following steps:

step one, raw material coal and high-temperature crude gas generated by a catalytic gasification unit are introduced into a catalytic pyrolysis unit, the raw material coal and the high-temperature crude gas are subjected to a pyrolysis reaction to generate coal coke, crude gas, tar and coal ash, wherein the coal coke is introduced into the catalytic gasification unit, and the coal ash is introduced into a mortar gasification unit;

introducing oxygen and water into the mortar gasification unit, wherein the oxygen, the water, the furnace ash and the coal ash are subjected to combustion reaction, coal gasification reaction and water gas shift reaction to generate high-temperature wet coal gas and ash slag, and the high-temperature wet coal gas is introduced into the catalytic gasification unit;

and step three, performing coal gasification reaction, water gas shift reaction and methanation reaction on the high-temperature wet coal gas and the coal coke in the catalytic gasification unit to generate high-temperature raw coal gas and furnace ash, wherein the furnace ash is introduced into the mortar gasification unit in the step two, and the high-temperature raw coal gas is introduced into the catalytic pyrolysis unit in the step one.

The coal coke, the crude gas, the tar and the coal ash generated by the catalytic pyrolysis unit are firstly introduced into a gas-solid separation unit for gas-solid separation, and then introduced into a separation unit;

the separation unit separates carbon monoxide, hydrogen and methane in the crude gas generated by the catalytic pyrolysis unit to obtain a gas product, separates the generated tar to obtain a tar product, and separates coal ash to be introduced into the catalyst recovery unit;

the furnace ash generated by the catalytic gasification unit and the coal ash separated by the separation unit are firstly introduced into a catalyst recovery unit for catalyst recovery, and then introduced into a mortar preparation unit, and the prepared mortar is introduced into a mortar gasification unit;

the high-temperature crude gas generated by the catalytic gasification unit is firstly introduced into the waste heat boiler unit for heat exchange and temperature reduction, and then is introduced into the catalytic pyrolysis unit.

Compared with the prior art, the technical scheme provided by the embodiment of the disclosure has the following advantages: the mortar gasification unit is used as a gas supply and heat supply unit of the system and provides required steam, coal gas and heat for the whole system, wherein combustion reaction, coal gasification reaction and water gas shift reaction mainly occur; the catalytic gasification unit is a core unit of the system and is a main reaction unit for generating a gas product, and high-temperature wet gas generated by the mortar gasification unit and coal coke generated by the catalytic pyrolysis unit are used for generating gas, wherein the gas mainly generates a coal gasification reaction, a water gas shift reaction and a methanation reaction; the catalytic pyrolysis unit is an important component of the system, is a generation unit of a tar byproduct of the system, can regulate and control the quality and yield of tar through operation, and simultaneously improves the generation rate of methane, wherein the pyrolysis reaction and the methanation reaction mainly occur; the three reaction units of catalytic pyrolysis, catalytic gasification and mortar gasification are creatively and orderly combined by the arrangement of the three units, cold materials are in reverse contact with hot coal gas in different reaction units, reasonable control of coal low-temperature pyrolysis, coal coke medium-temperature gasification and mortar high-temperature combustion reaction is realized, control of different reaction temperatures is realized, effective matching of heat is realized, graded conversion and cascade utilization of coal are realized, generated products of each reaction are effectively utilized, carbon conversion rate is improved, and maximization of target product quantities such as tar and methane is guaranteed.

Drawings

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate embodiments consistent with the present disclosure and together with the description, serve to explain the principles of the disclosure.

In order to more clearly illustrate the embodiments or technical solutions in the prior art of the present disclosure, the drawings used in the description of the embodiments or prior art will be briefly described below, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without inventive exercise.

Fig. 1 is a schematic view of a high-efficiency catalytic gasification system for coal provided by an embodiment of the disclosure.

Wherein, 1, a mortar gasification unit; 2. a catalytic gasification unit; 3. a catalytic pyrolysis unit; 4. a separation unit; 5. a mortar preparation unit; 6. a catalyst recovery unit; 7. a gas-solid separation unit; 8. a waste heat boiler unit.

Detailed Description

In order that the above objects, features and advantages of the present disclosure may be more clearly understood, aspects of the present disclosure will be further described below. It should be noted that the embodiments and features of the embodiments of the present disclosure may be combined with each other without conflict.

In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present disclosure, but the present disclosure may be practiced in other ways than those described herein; it is to be understood that the embodiments disclosed in the specification are only a few embodiments of the present disclosure, and not all embodiments.

As shown in fig. 1, the present disclosure provides a high-efficiency catalytic coal gasification system, which includes a mortar gasification unit 1, a catalytic gasification unit 2, and a catalytic pyrolysis unit 3; the catalytic pyrolysis unit 3 is used for introducing raw material coal and the high-temperature raw gas generated by the catalytic gasification unit 2, and the raw material coal and the high-temperature raw gas are subjected to pyrolysis reaction and methanation reaction to generate coal coke, raw gas, tar and coal ash; the mortar gasification unit 1 is used for introducing oxygen, water, furnace ash generated by the catalytic gasification unit 2 and coal ash generated by the catalytic pyrolysis unit 3, and the oxygen, the water, the furnace ash and the coal ash generate combustion reaction, coal gasification reaction and water gas shift reaction to generate high-temperature wet coal gas and ash; the catalytic gasification unit 2 is used for introducing high-temperature wet coal gas generated by the mortar gasification unit 1 and coal char generated by the catalytic pyrolysis unit 3, and the high-temperature wet coal gas and the coal char generate coal gasification reaction, water gas shift reaction and methanation reaction to generate high-temperature raw coal gas and furnace dust; the reaction temperatures of the mortar gasification unit 1, the catalytic gasification unit 2 and the catalytic pyrolysis unit 3 are sequentially decreased progressively.

Compared with the prior art, the mortar gasification unit 1 is used as a gas supply and heat supply unit of the system, and provides required steam, coal gas and heat for the whole system, wherein combustion reaction, coal gasification reaction and water gas shift reaction mainly occur; the catalytic gasification unit 2 is a core unit of the system, is a main reaction unit for generating a gas product, and generates gas by using high-temperature wet gas generated by the mortar gasification unit 1 and coal tar generated by the catalytic pyrolysis unit 3, wherein the gas mainly generates a coal gasification reaction, a water gas shift reaction and a methanation reaction; the catalytic pyrolysis unit 3 is an important component of the system, is a generation unit of a tar byproduct of the system, can regulate and control the quality and yield of tar through operation, and can improve the generation rate of methane, wherein a pyrolysis reaction and a methanation reaction mainly occur; the three reaction units of catalytic pyrolysis, catalytic gasification and mortar gasification are creatively and orderly combined by the arrangement of the three units, cold materials are in reverse contact with hot coal gas in different reaction units, reasonable control of coal low-temperature pyrolysis, coal coke medium-temperature gasification and mortar high-temperature combustion reaction is realized, control of different reaction temperatures is realized, effective matching of heat is realized, graded conversion and cascade utilization of coal are realized, generated products of each reaction are effectively utilized, carbon conversion rate is improved, and maximization of target product quantities such as tar and methane is guaranteed.

Specifically, the 'reverse contact of cold materials and hot coal gas in different reaction units' is embodied in the following two aspects:

firstly, materials in all units in the system are in reverse contact, normal-temperature raw coal enters a low-temperature catalytic pyrolysis unit 3, generated coal coke is introduced into a medium-temperature catalytic gasification unit 2, and generated furnace ash is introduced into a high-temperature mortar gasification unit 1, so that the step conversion of the coal is realized, and the yield of byproducts and the carbon conversion rate are improved; high-temperature wet gas generated from the mortar gasification unit 1 sequentially passes through the medium-temperature catalytic gasification unit 2 and the low-temperature catalytic pyrolysis unit 3 and is correspondingly in reverse contact with coal coke and raw material coal, so that gradient utilization of heat is realized, and the heat efficiency of the system is improved;

secondly, in the single reaction unit, in reverse contact, such as the catalytic pyrolysis unit 3, normal-temperature raw material coal is introduced from the middle upper part and moves downwards, the generated coal coke is discharged from the lower part, high-temperature raw gas is introduced from the lower part and flows upwards to generate new raw gas to be discharged; for example, in the catalytic gasification unit 2, the coal coke is introduced from the middle upper part and moves downwards, the generated furnace ash is discharged from the lower part, the high-temperature wet coal gas is introduced from the lower part, and flows upwards to generate new high-temperature crude coal gas to be discharged; the cold and hot materials are in reverse contact in a single reaction unit, so that the carbon conversion efficiency and the thermal efficiency of the system are improved.

In some embodiments, as shown in fig. 1, the system further comprises a separation unit 4 and a mortar preparation unit 5, wherein the separation unit 4 is used for separating crude gas, tar and coal ash generated by the catalytic pyrolysis unit 3; the mortar preparation unit 5 is used for preparing mortar from the coal ash separated by the separation unit 4 and the furnace ash generated by the catalytic gasification unit 2, and the prepared mortar is introduced into the mortar gasification unit 1. The device also comprises a catalyst recovery unit 6, wherein the catalyst recovery unit 6 is used for recovering the catalyst in the furnace dust generated by the catalytic gasification unit 2 and the coal ash generated by the catalytic pyrolysis unit 3, and the furnace dust and the coal ash recovered by the catalyst are introduced into the mortar preparation unit 5.

The furnace ash produced in the catalytic gasification unit 2 and the coal ash separated in the separation unit 4 contain a certain amount of catalyst, water may be introduced into the catalyst recovery unit 6 to dissolve the catalyst in water, the catalyst recovery unit 6 may be provided with a solid-liquid separation device to separate and recover the catalyst solution, or a digestion solution may be introduced to recover the water-insoluble catalyst, and the slurry obtained by separation may be introduced into the slurry preparation unit 5 to further prepare slurry.

In some embodiments, as shown in fig. 1, a gas-solid separation unit 7 is disposed between the catalytic pyrolysis unit 3 and the separation unit 4, an inlet of the gas-solid separation unit 7 is connected to the catalytic pyrolysis unit 3, a gas outlet of the gas-solid separation unit 7 is connected to the separation unit 4, and a dust outlet of the gas-solid separation unit 7 is connected to the catalytic gasification unit 2. The catalytic pyrolysis unit 3 can generate a certain amount of fly ash through reaction, the fly ash discharged from an air outlet at the upper part of the catalytic pyrolysis unit 3 can be separated and recovered as far as possible by adopting the gas-solid separation unit 7, and then the fly ash is introduced into the catalytic gasification unit 2 for gasification reaction, so that the carbon conversion rate is fully improved.

In some embodiments, as shown in fig. 1, a waste heat boiler unit 8 is disposed between the catalytic gasification unit 2 and the catalytic pyrolysis unit 3, and the waste heat boiler unit 8 is used for performing heat exchange and temperature reduction on the high-temperature raw gas introduced into the catalytic pyrolysis unit 3 from the catalytic gasification unit 2. The catalytic pyrolysis unit 3 is mainly used for carrying out pyrolysis reaction and methanation reaction, the temperature requirement is not high, so that the waste heat boiler unit 8 is arranged for properly cooling high-temperature raw gas, and the high-grade heat of the raw gas is utilized to produce byproduct steam, so that the technical economy is improved.

In some embodiments, the reaction temperature of the mortar gasification unit 1 is 850 to 1300 ℃. The slurry gasification unit 1 is subjected to a combustion reaction to supply heat to the whole system, so that the reaction temperature is high.

In some embodiments, the reaction temperature of catalytic gasification unit 2 is 650 to 800 ℃. The temperature is suitable for the reaction of high-temperature wet coal gas and coal coke to generate coal gas.

In some embodiments, the reaction temperature of the catalytic pyrolysis unit 3 is 400 to 600 ℃. The temperature is suitable for the pyrolysis reaction and the methanation reaction of the raw material coal and the high-temperature raw gas.

The high-efficiency catalytic gasification method for coal, provided by the disclosure, comprises the following steps:

firstly, raw material coal and high-temperature crude gas generated by the catalytic gasification unit 2 are introduced into the catalytic pyrolysis unit 3, and the raw material coal and the high-temperature crude gas are subjected to pyrolysis reaction to generate coal coke, crude gas, tar and coal ash, wherein the coal coke is introduced into the catalytic gasification unit 2, and the coal ash is introduced into the mortar gasification unit 1;

secondly, introducing oxygen and water into the mortar gasification unit 1, wherein the oxygen, the water, the furnace ash and the coal ash are subjected to combustion reaction, coal gasification reaction and water gas shift reaction to generate high-temperature wet coal gas and ash, and the high-temperature wet coal gas is introduced into the catalytic gasification unit 2;

and step three, performing coal gasification reaction, water gas shift reaction and methanation reaction on the high-temperature wet coal gas and the coal coke in the catalytic gasification unit 2 to generate high-temperature raw coal gas and furnace ash, wherein the furnace ash is introduced into the mortar gasification unit 1 in the step two, and the high-temperature raw coal gas is introduced into the catalytic pyrolysis unit 3 in the step one.

In some embodiments, the coal coke, the crude gas, the tar and the coal ash generated by the catalytic pyrolysis unit 3 are firstly introduced into the gas-solid separation unit 7 for gas-solid separation, and then introduced into the separation unit 4;

the separation unit 4 separates carbon monoxide, hydrogen and methane in the crude gas generated by the catalytic pyrolysis unit 3 to be used as a gas product, separates the generated tar to be used as a tar product, and separates coal ash to be introduced into the catalyst recovery unit 6;

the furnace ash generated by the catalytic gasification unit 2 and the coal ash separated by the separation unit 4 are firstly fed into a catalyst recovery unit 6 for catalyst recovery, and then fed into a mortar preparation unit 5, and the prepared mortar is fed into a mortar gasification unit 1;

the high-temperature crude gas generated by the catalytic gasification unit 2 is firstly introduced into the waste heat boiler unit 8 for heat exchange and temperature reduction, and then is introduced into the catalytic pyrolysis unit 3.

The specific working process of one embodiment of the invention is as follows:

the mortar gasification unit 1 is used as a gas supply and heat supply unit of the system and provides required steam, coal gas and heat for the whole system. The slurry gasification unit 1 adopts a gasification furnace which can be selected from but not limited to a single-nozzle water-coal-slurry gasification furnace, a multi-nozzle water-gas gasification furnace, a water-coal-slurry boiler and the like, the slurry with certain carbon content sent by the slurry preparation unit 5 and oxygen are fully reacted in the gasification furnace to generate high-temperature wet gas, the high-temperature wet gas is introduced into the catalytic gasification unit 2 from a gas outlet of the gasification furnace, ash is discharged from a discharge outlet, the gasification reaction temperature is 850-1300 ℃, and the reaction pressure is 4.5-6.0 MPa. When the carbon content of the mortar is low and is not enough to maintain the reaction temperature, the carbon content of the furnace ash can be increased by regulating the catalytic gasification unit 2, and the raw material coal can also be directly added into the mortar preparation unit 5.

The main components of the high-temperature wet coal gas are carbon dioxide, superheated steam, hydrogen and carbon monoxide, the temperature is 850-1300 ℃, and the pressure is 4.5-5.5 MPa. The main chemical reactions of the mortar gasification unit 1 are:

and (3) combustion reaction: c + O₂→CO+CO₂

Coal gasification reaction: c + H₂O→CO+H₂

Water gas shift reaction: CO + H₂O→CO₂+H₂。

The catalytic gasification unit 2 is a core unit of the system and is a main reaction unit for producing gas products. The fly ash sent by the coal coke and gas-solid separation unit 7 sent by the catalytic pyrolysis unit 3 and the high-temperature wet gas sent by the mortar gasification unit 1 fully generate catalytic gasification reaction in the catalytic gasification unit 2, so that the high-efficiency conversion of carbon in the coal coke and the fly ash is realized, high-temperature crude gas and furnace ash are generated, the high-temperature crude gas is introduced into the catalytic pyrolysis unit 3 from the gas outlet of the gasification furnace, and the furnace ash is discharged to the catalyst recovery unit 6 from the discharge port. The catalytic gasification unit 2 adopts a gasification furnace which can be selected from but not limited to a high-pressure fluidized bed, the reaction temperature is 650-800 ℃, and the reaction pressure is 3.5-4.5 MPa.

The retention time of the catalytic gasification reaction can be adjusted according to the requirement of the mortar gasification unit 1, so as to control the carbon content of the furnace ash, generally controlling the carbon content to be 10-35%, and simultaneously discharging the catalyst out of the gasification furnace along with the furnace ash into the catalyst recovery unit 6.

The high-temperature raw gas mainly comprises hydrogen, carbon monoxide, methane, carbon dioxide, steam and the like, the temperature is 650-800 ℃, and the pressure is 3.5-4.0 MPa. The main chemical reactions of the catalytic gasification unit 2 are:

coal gasification reaction: c + H₂O→CO+H₂

Water gas shift reaction: CO + H₂O→CO₂+H₂

Methanation reaction: CO + H₂→CH₄+H₂O。

The catalytic pyrolysis unit 3 is an important component of the system, is a generation unit of tar byproducts of the system, can regulate and control the quality and yield of tar through operation, and can improve the methane generation rate at the same time. The high-temperature raw gas sent by the catalytic gasification unit 2 is controlled by a waste heat boiler unit 8 to be cooled and fully contacted with the catalyst-loaded raw coal, the raw coal can be bituminous coal, the particle size of the raw coal is less than 5mm, the raw coal is loaded with an alkali metal catalyst, and the moisture of the dried raw coal is controlled to be less than 10%. The raw material coal is pyrolyzed rapidly to generate crude gas and coal coke rich in tar. The catalytic pyrolysis unit 3 can be selected from, but not limited to, a high-pressure fluidized bed, a fixed bed, a transport bed and the like, the pyrolysis reaction temperature is 400 to 600 ℃, and the pyrolysis pressure is 3.0 to 4.0 MPa. The main chemical reactions of the catalytic pyrolysis unit are:

and (3) pyrolysis reaction: coal hydrogen-rich and steam-rich environment → volatile component + tar + coal tar

Methanation reaction: CO + H₂→CH₄+H₂O。

Because the catalytic pyrolysis unit 3 is internally provided with the coal coke bed material with a certain height and containing the catalyst, carbon monoxide and hydrogen in the raw gas generated by catalytic gasification at the low temperature of 400-600 ℃ and the high pressure of 3.0-4.0 MPa can further generate methanation reaction, and the methane content in the gas is further improved.

The waste heat boiler unit 8 is positioned between the catalytic gasification unit 2 and the catalytic pyrolysis unit 3, and is mainly used for timely regulating and controlling the temperature of the high-temperature raw gas according to the coal quality characteristics and the operating temperature of the catalytic pyrolysis unit 3, and simultaneously recovering the heat of the high-temperature raw gas to produce a medium-pressure superheated steam as a byproduct for use by a system or power generation. The waste heat boiler unit 8 can be selected from, but not limited to, a vertical fire tube boiler or a horizontal fire tube boiler, and can be selected according to the dust content in the raw gas.

The gas-solid separation unit 7 and the separation unit 4 are post-treatment units of the whole system, and are mainly used for carrying out gas-solid separation and cooling on the crude gas sent from the catalytic pyrolysis unit 3, and the fly ash separated firstly returns to the catalytic gasification unit 2 for reuse, so that the carbon conversion rate of the system is improved. The gas-solid separation unit 7 can be selected from, but not limited to, a cyclone separator, a metal filter, a ceramic filter and a cloth bag filter, and can also be used in combination of several of the above. The separation unit 4 is mainly used for realizing effective separation of gas, water, oil and dust, wherein the gas is used as a coal gas product, the oil is used as a tar product, and the water and the dust are mixed into coal ash and enter the catalyst recovery unit 6. The separation unit 4 is generally a combination of several devices or systems, mainly composed of a cooler, a water washing tower, a separation tank, and the like.

The catalyst recovery unit 6 is mainly used for recovering the catalyst in the furnace dust and the coal slime, and the common method comprises the steps of recovering the soluble part of the catalyst by washing, digesting and recovering the insoluble part of the catalyst, and producing a catalyst solution product after washing and digesting to realize recycling;

the mortar preparation unit 5 receives the mortar from the catalyst recovery unit 6, and uniformly mixes the mortar, water, and additives by a mill to prepare mortar as a main raw material of the mortar gasification unit 1. Depending on the operational requirements of the mortar gasification unit 1, a certain amount of raw coal may also be added during the pulping process, the mortar concentration being typically controlled between 15% and 50%.