Coal tar in-situ high-temperature catalytic cracking coal gasifier device and process

Abstract

The present invention relates to the field of gasification in atmospheric pressure fixed-bed gasifiers, particularly a coal tar in-situ high-temperature catalytic cracking gasifier device and process. The gasifier is a three-stage gasifier. The drying section is connected to the dry distillation section via a second stoker, which is then connected to the gasification section via a third stoker. The lower portion of the dry distillation section is connected to the upper portion of the drying section via a pipeline. The top of the dry distillation section is connected to the gasification reaction layer at the bottom of the gasification section via a gas guide pipe. The drying section is connected to the top of the gasification section, and a waste heat recovery device is installed on the gas outlet pipeline at the top of the gasification section. A portion of the pressurized gas is returned to the dry distillation section for combustion in the backfire gas burner. The hot flue gas from the combustion enters the dry distillation section to dry distill the coal material. The resulting tar-rich dry distillation gas is discharged from the top of the dry distillation section. The remaining portion of the gas enters an indirect cooler to cool the gas. The tar in the dry distillation gas is catalytically cracked to produce gas rich in non-condensable combustible gases, with a tar cracking rate exceeding 85%.

Description

Technical Field

[0001] The present invention relates to the field of gasification by atmospheric pressure fixed bed gasifiers, in particular to a coal tar in-situ high-temperature catalytic cracking gasifier device and process. Background Art

[0002] When bituminous coal or lignite is gasified in a conventional atmospheric fixed-bed gasifier, the by-product coal tar is mixed in the discharged gas. During the gas cooling and purification process, the coal tar condenses and precipitates, leading to environmental pollution such as coal tar and its derived VOCs.

[0003] In the literature on high-temperature cracking of coal tar disclosed in the industry, no relevant reports on the in-situ cracking of by-product tar using a fixed-bed gasifier have been found.

[0004] After searching the relevant and similar keywords disclosed on the website of the State Intellectual Property Office, the contents recorded in the following documents: CN114231317A, CN108913179A, CN103305282A, did not disclose the issue of in-situ cracking of tar; no public documents have been found that show that self-produced coal tar can be cracked in situ in the device and / or process of a conventional three-stage gasifier. Summary of the Invention

[0005] The purpose of the present invention is to overcome the shortcomings of the background technology. By dividing the gasifier into a drying section, a dry distillation section and a gasification section, the dry distillation gas rich in gaseous tar produced in the dry distillation section is diverted to the gasification reaction layer of the gasification section. Under the catalytic action of the semi-coke in the gasification reaction layer, the gaseous tar in the dry distillation gas is catalytically cracked under high temperature conditions to form a gas rich in non-condensable combustible gas. The gas is mixed with the dry distillation gas and the gasified gas produced in the gasification section and discharged from the gasifier, thereby achieving the purpose of achieving a coal gas that is basically tar-free in the gas discharged from the gasifier.

[0006] The coal tar in-situ high-temperature catalytic cracking gasifier device is implemented using the following technical solutions:

[0007] A gasifier device for in-situ high-temperature catalytic cracking of coal tar, the gasifier being a three-stage gasifier, comprising a drying section, a dry distillation section, and a gasification section from top to bottom, the drying section being connected to a coal storage bin via a first stoker, the drying section being connected to the dry distillation section via a second stoker, the dry distillation section being connected to the gasification section via a third stoker, a backfire gas burner being provided at the lower portion of the dry distillation section, the backfire gas burner being connected to an upper pipeline of the drying section via a gas compressor; the top of the dry distillation section being connected to a gasification reaction layer at the lower portion of the gasification section via a gas guide pipe; the drying section being connected to the top of the gasification section, and a waste heat recovery device being installed on the gas outlet pipeline at the top of the gasification section.

[0008] The coal tar in-situ high-temperature catalytic cracking gasifier device adopts the following preferred scheme:

[0009] A plurality of backfire gas burners are arranged at the lower part of the dry distillation section.

[0010] The waste heat recovery device includes a cyclone dust collector, a partition water seal, a waste heat recovery device and an indirect cooling thermostat. The cyclone dust collector is connected to the top of the gasification section through a gas outlet pipeline, the cyclone dust collector is connected to the partition water seal, the partition water seal is connected to the waste heat recovery device, the waste heat recovery device is connected to the indirect cooling thermostat, and the indirect cooling thermostat is connected to the annular air duct of the drying section through a pipeline.

[0011] The upper part of the drying section is connected to the electrostatic precipitator through a pipeline, the electrostatic precipitator is connected to the gas compressor, the gas compressor is respectively connected to the retorting section backfire gas burner and the indirect cooler, and the indirect cooler is connected to the drip catcher.

[0012] The process of in-situ high-temperature catalytic cracking of coal tar in the gasifier unit is implemented using the following scheme:

[0013] S1. Use anthracite or coke with low volatile carbon content as transition gasification raw material to start the three-stage gasifier.

[0014] ① Fill the dry distillation section with anthracite or coke, and fill the drying section with gasification coal for normal gasification;

[0015] ② The anthracite or coke in the dry distillation section is fed into the gasification section through the third stoker. The anthracite or coke fed into the gasification section undergoes an oxidation-reduction reaction at high temperature with the "air + steam" gasifying agent blown into the bottom of the gasifier to produce producer gas, which is then discharged from the top of the gasification section.

[0016] ③ As the coal level in the dry distillation section decreases, the second stoker gradually adds the bituminous coal in the drying section to the dry distillation section. As the coal level in the dry distillation section decreases, the first stoker gradually adds the bituminous coal in the coal storage bin to the dry distillation section.

[0017] S2, the producer gas from the top of the gasification section, with a temperature of 500-600°C, enters the cyclone dust collector through the gas outlet pipe of the gasifier, where it is subjected to dust removal at high temperature. The gas passes through the water seal and enters the waste heat recovery device to recover the high-temperature physical sensible heat of the gas and cool it down. The gas enters the intercooler thermostat, where the outlet gas temperature is tracked and the amount of cooling circulating water entering the intercooler thermostat is automatically adjusted to ensure that the outlet gas temperature of the intercooler thermostat is maintained at 200-300°C. The gas enters the drying section through the annular air duct at the bottom of the drying section, where the coal in the drying section is dried and cooled down. The gas is then discharged from the top outlet of the drying section and enters the electrostatic precipitator, where it is subjected to deep dust removal. The gas then enters the gas compressor for pressurization.

[0018] S3. The coal gas pressurized by the gas compressor is divided into two paths: ① One path of the coal gas flows back to the backfire gas burner through the backfire gas pipeline for combustion, and the high-temperature hot flue gas generated after combustion enters the dry distillation section to carry out dry distillation treatment on the coal material, and the generated tar-rich dry distillation coal gas is discharged from the top of the dry distillation section; the dry distillation coal gas discharged from the top of the dry distillation section is introduced into the gasification reaction layer at the bottom of the gasification section through the dry distillation coal gas guide pipe, and under the catalytic action of the semi-coke in the gasification reaction layer, the gaseous tar in the dry distillation coal gas is catalytically cracked under high temperature to form coal gas rich in non-condensable combustible gas, and is discharged through the top of the gasification section together with the gasified coal gas generated in the gasification section; ② The other path of the coal gas enters the indirect cooler for cooling treatment, and the coal gas temperature drops to 35-45℃, and then the coal gas enters the droplet collector, and the mechanical water droplets carried in the coal gas are captured and supplied to the gas users.

[0019] Optimal process solution:

[0020] By tracking the temperature of the dry distillation gas derived from the dry distillation section 5, the flow rate of the backfire gas is automatically adjusted to ensure that the temperature of the dry distillation gas derived from the top of the dry distillation section 5 is maintained at a temperature of 450°C-550°C.

[0021] The device and process employing the above-described technical solution offer the following advantages: 1. The heat medium used to dry the coal in the drying section is producer gas, which has been cooled to a temperature below 300°C (e.g., 250°C) after waste heat recovery. Maintaining the gas temperature below 300°C ensures that only coal drying occurs within the drying section, preventing the production of pyrolysis tar. Furthermore, using the relatively low-temperature gas recovered from waste heat to dry the coal in the drying section fully utilizes the physical sensible heat of the producer gas.

[0022] 2. The heat medium used for dry distillation of coal materials in the dry distillation section is the hot flue gas generated by the combustion of the backfired gas. The backfired gas is taken from the generator gas that is discharged from the drying section, has undergone deep dust removal, and has been pressurized by a gas compressor.

[0023] 3. The gas exiting the dry distillation section is kept at a high temperature (e.g., around 500°C) above 450°C, ensuring that the tar in the dry distillation gas remains in gaseous form. The dry distillation gas, rich in gaseous tar, is then drawn from the top of the dry distillation section and directed into the gasification reaction layer of the gasification section, where the gaseous tar is catalytically cracked at high temperatures into gas rich in non-condensable combustible gases.

[0024] The dry distillation gas rich in gaseous tar produced in the dry distillation section is directed to the gasification reaction layer of the gasification section. Under the catalytic action of the semi-coke in the gasification reaction layer, the gaseous tar in the dry distillation gas is catalytically cracked at high temperature into coal gas rich in non-condensable combustible gas. The coal gas is mixed with the gasified coal gas produced in the gasification section and discharged to the gasifier, thereby achieving a tar cracking rate of more than 85% in the coal gas discharged from the gasifier. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a structural schematic diagram of the present invention. DETAILED DESCRIPTION

[0026] The present invention is described in detail below with reference to the accompanying drawings:

[0027] See attached Figure 1 In the figure: coal storage bin 1, first stoker 2, drying section 3, annular air duct 3-1, second stoker 4, dry distillation section 5, gas guide pipe 5-1, backfire gas burner 5-2, third stoker 6, gasification section 7, gasification reaction layer 7-1, cyclone dust collector 8, partition water seal 9, waste heat recovery device 10, indirect cooling thermostat 11, electrostatic precipitator 12, gas compressor 13, backfire gas pipeline 13-1, indirect cooler 14, drip collector 15.

[0028] A coal tar in-situ high-temperature catalytic cracking gasifier device is disclosed. The gasifier is a three-stage gasifier, primarily consisting of a drying section 3, a dry distillation section 5, and a gasification section 7, from top to bottom. The drying section 3 is connected to a coal storage bin 1 via a first stoker 2. The drying section 3 is connected to the dry distillation section 5 via a second stoker 4 (i.e., the drying section 3 and the dry distillation section 5 are connected via the second stoker 4, but no cross-flow of gas is allowed through the second stoker 4). The dry distillation section 5 is connected to the gasification section 7 via a third stoker 6 (i.e., the dry distillation section 5 and the gasification section 7 are connected via the third stoker 6, but no cross-flow of gas is allowed through the third stoker 6). A waste heat recovery device is installed on the gas outlet pipeline 7-1 at the top of the gasification section 7.

[0029] The waste heat recovery device comprises a cyclone dust collector 8, a partition water seal 9, a waste heat recovery device 10, and an indirect cooling thermostat 11. The cyclone dust collector 8 is connected to the top of the gasification section 7 via a coal gas outlet pipeline 7-2. The cyclone dust collector 8 is connected to the partition water seal 9, which is in turn connected to the waste heat recovery device 10. The waste heat recovery device 10 is connected to the indirect cooling thermostat 11. The indirect cooling thermostat 11 is connected via a pipeline to an annular air duct 3-1 provided at the bottom of the drying section 3. The annular air duct 3-1 ensures that the dry gas introduced into the drying section 3 is evenly distributed within the drying section 3, thereby uniformly heating the coal in the drying section 3.

[0030] The lower portion of the dry distillation section 5 is equipped with multiple backdraft gas burners 5-2. The number of backdraft gas burners 5-2 is related to the inner diameter of the gasifier. For example, a gasifier with an inner diameter of Φ3.6m is equipped with four backdraft gas burners in the dry distillation section. The backdraft gas burners 5-2 are connected to a gas compressor 13 via a backdraft gas pipeline 13-1. The gas compressor 13 is connected to an electrostatic precipitator 12, which is connected to the upper pipeline of the drying section 3 via a pipeline.

[0031] The top of the dry distillation section 5 is connected to the gasification reaction layer 7-1 at the bottom of the gasification section through a gas guide pipe 5-1. An annular gas channel 3-1 is set at the bottom of the drying section 3, and the annular gas channel 3-1 is connected to the top of the gasification section 7 through a waste heat recovery device.

[0032] The upper part of the drying section 3 is connected to the electrostatic precipitator 12 through a pipeline, the electrostatic precipitator 12 is connected to the gas compressor 13, the gas compressor 13 is respectively connected to the backfire gas burner 5-1 of the dry distillation section 5 and the indirect cooler 14, and the indirect cooler 14 is connected to the drip collector 15.

[0033] The process of in-situ high-temperature catalytic cracking of self-produced coal tar in a three-stage gasifier is carried out as follows:

[0034] S1. Use anthracite or coke with low volatile carbon content as transition gasification raw material to start the three-stage gasifier.

[0035] ① Fill the dry distillation section 5 with anthracite or coke, and fill the drying section 3 with the gasification coal used during normal gasification: bituminous coal or lignite.

[0036] ② The anthracite or coke in the dry distillation section 5 is successively fed into the gasification section 7 through the third stoker 6. The anthracite or coke fed into the gasification section 7 undergoes an oxidation-reduction reaction with the "air + steam" gasifying agent blown into the bottom of the gasifier under a high temperature state to produce producer gas, which is then discharged out of the gasifier from the top of the gasification section 7.

[0037] ③ As the coal level in the dry distillation section 5 decreases, the second stoker 4 gradually adds the bituminous coal in the drying section 3 to the dry distillation section 5. As the coal level in the dry distillation section 3 decreases, the first stoker 2 gradually adds the bituminous coal in the coal storage bin 1 to the dry distillation section 3.

[0038] S2. The producer gas extracted from the top of the gasification section 7 has a temperature of approximately 500-600°C. The gas enters the cyclone dust collector 8 through the gas producer gas outlet pipe 7-2, where the gas is subjected to dust removal treatment at high temperature. The gas then passes through the partition water seal 9 and enters the waste heat recovery device 10 to recover and utilize the high-temperature physical sensible heat of the gas while cooling the gas. The gas enters the indirect cooling thermostat 11, where the outlet gas temperature of the indirect cooling thermostat 11 is tracked and the amount of cooling circulating water entering the indirect cooling thermostat 11 is automatically adjusted through PLC control, thereby ensuring that the outlet gas temperature of the indirect cooling thermostat 11 is maintained at a certain temperature below 300°C (for example, 250°C).

[0039] The gas temperature is maintained at a certain temperature below 300℃. Its purpose is to ensure that only coal drying can be carried out in the drying section, and no pyrolysis tar is produced. At the same time, the use of lower temperature gas to dry the coal in the drying section makes full use of the physical sensible heat of the gasifier.

[0040] The coal gas then enters the drying section 3 through the annular air duct 3-1 at the bottom of the drying section 3, dries the coal material in the drying section 3, and cools down at the same time. The coal gas is discharged from the top outlet of the drying section 3 and enters the electrostatic precipitator 12, where the coal gas is deeply dust-removed. The coal gas then enters the gas compressor 14 to be pressurized.

[0041] S3. The gas pressurized by the gas compressor 4 is divided into two paths: ① One path of the gas flows back through the backfire gas pipeline 13-1 to the backfire gas burner 5-1 for combustion. The high-temperature hot flue gas generated after combustion enters the dry distillation section 5 to carry out dry distillation of the coal material, and the generated tar-rich dry distillation gas is discharged from the top of the dry distillation section 5; by tracking the temperature of the dry distillation gas discharged from the dry distillation section 5, the flow rate of the backfire gas is automatically adjusted to ensure that the temperature of the dry distillation gas discharged from the top of the dry distillation section 5 is maintained at a certain temperature higher than 450°C (for example, 500°C), ensuring that the tar contained in the gas discharged from the dry distillation section is in gaseous form. The tar-rich dry distillation gas from the top of the dry distillation section 5 is introduced into the gasification reaction layer 7-1 at the bottom of the gasification section 7 through the dry distillation gas guide pipe 5-1. Under the catalytic action of the semi-coke in the gasification reaction layer 7-1, the gaseous tar in the dry distillation gas is catalytically cracked at high temperature to produce a gas rich in non-condensable combustible gas. The gas is then discharged through the gas outlet pipe 7-2 at the top of the gasification section 7 together with the dry distillation gas generated by the gasification section 7. ② The other gas path enters the indirect cooler 14 for cooling, reducing the gas temperature to 35-45°C. The gas then enters the drip collector 15, where mechanical water droplets carried in the gas are removed before being supplied to gas users.

[0042] In the above description, the stokers are defined as first, second, etc. only to distinguish different stokers and do not limit the order of priority in the process scheme. In this application, for the currently commonly used gasified bituminous coal, the tar cracking rate can reach more than 85%.

[0043] The tar cracking rate is related to the catalytic properties of the semi-coke in the gasification reaction layer and the temperature of the gasification reaction layer. The catalytic properties of the semi-coke are related to the quality of the gasified coal, and the temperature of the gasification reaction layer is related to the CO reaction activity of the gasification coal (the temperature of the gasification reaction layer is generally the temperature corresponding to the CO reduction rate α of the gasification coal = 60%). The better the catalytic properties of the semi-coke, the higher the temperature of the gasification reaction layer, and the higher the tar cracking rate, as shown in the following table:

[0044]

Claims

1. A coal tar in-situ high-temperature catalytic cracking gasifier device, the gasifier being a three-stage gasifier comprising, from top to bottom, a drying section, a dry distillation section, and a gasification section, the drying section being connected to a coal storage bin via a first stoker, characterized in that: The drying section is connected to the dry distillation section via a second stoker, and the dry distillation section is connected to the gasification section via a third stoker. A backfire gas burner is provided at the lower part of the dry distillation section, and the backfire gas burner is connected to the upper pipeline of the drying section through a gas compressor; The top of the dry distillation section is connected to the gasification reaction layer at the bottom of the gasification section through a gas guide pipe; The drying section is connected to the top of the gasification section, and a waste heat recovery device is installed on the gas outlet pipeline at the top of the gasification section.

2. The coal tar in-situ high-temperature catalytic cracking gasifier device according to claim 1, characterized in that: An annular air duct is provided at the lower part of the drying section, and the annular air duct is connected to the top of the gasification section through a waste heat recovery device.

3. The coal tar in-situ high-temperature catalytic cracking gasifier device according to claim 1, characterized in that: A plurality of backfire gas burners are arranged at the lower part of the dry distillation section.

4. The coal tar in-situ high-temperature catalytic cracking gasifier device according to claim 1, characterized in that: The waste heat recovery device includes a cyclone dust collector, a partition water seal, a waste heat recovery device and an indirect cooling thermostat. The cyclone dust collector is connected to the top of the gasification section through a gas outlet pipeline, the cyclone dust collector is connected to the partition water seal, the partition water seal is connected to the waste heat recovery device, the waste heat recovery device is connected to the indirect cooling thermostat, and the indirect cooling thermostat is connected to the annular air duct of the drying section through a pipeline.

5. The coal tar in-situ high-temperature catalytic cracking gasifier device according to claim 1, characterized in that: The upper part of the drying section is connected to the electrostatic precipitator through a pipeline, the electrostatic precipitator is connected to the gas compressor, the gas compressor is respectively connected to the retorting section backfire gas burner and the indirect cooler, and the indirect cooler is connected to the drip catcher.

6. A coal tar in-situ high-temperature catalytic cracking gasifier process according to any one of claims 1 to 5, characterized in that: S1. Use anthracite or coke with low volatile carbon content as transition gasification raw material to start the three-stage gasifier. ① Fill the dry distillation section with anthracite or coke, and fill the drying section with gasification coal for normal gasification; ② The anthracite or coke in the dry distillation section is fed into the gasification section through the third stoker. The anthracite or coke fed into the gasification section undergoes an oxidation-reduction reaction at high temperature with the "air + steam" gasifying agent blown into the bottom of the gasifier to produce producer gas, which is then discharged from the top of the gasification section. ③ As the coal level in the dry distillation section decreases, the second stoker gradually adds the bituminous coal in the drying section to the dry distillation section. As the coal level in the dry distillation section decreases, the first stoker gradually adds the bituminous coal in the coal storage bin to the dry distillation section. S2, the producer gas from the top of the gasification section, with a temperature of 500-600°C, enters the cyclone dust collector through the gas outlet pipe of the gasifier, where it undergoes dust removal at high temperature. The gas then passes through a water seal to enter the waste heat recovery device, where the high-temperature physical sensible heat of the gas is recovered and the gas is cooled. The gas then enters the intercooler thermostat, where the outlet gas temperature is tracked and the amount of cooling circulating water entering the intercooler thermostat is automatically adjusted through PLC control to ensure that the outlet gas temperature is maintained at 200-300°C. The gas then enters the drying section through the annular air duct at the bottom of the drying section, where the coal in the drying section is dried and cooled. The gas then passes through the top outlet of the drying section and enters the electrostatic precipitator, where it undergoes deep dust removal. The gas then enters the gas compressor for pressurization. S3. The coal gas pressurized by the gas compressor is divided into two paths: ① One path of the coal gas flows back to the backfire gas burner through the backfire gas pipeline for combustion, and the high-temperature hot flue gas generated after combustion enters the dry distillation section to carry out dry distillation treatment on the coal material, and the generated tar-rich dry distillation coal gas is discharged from the top of the dry distillation section; the dry distillation coal gas discharged from the top of the dry distillation section is introduced into the gasification reaction layer at the bottom of the gasification section through the dry distillation coal gas guide pipe, and under the catalytic action of the semi-coke in the gasification reaction layer, the gaseous tar in the dry distillation coal gas is catalytically cracked under high temperature to form coal gas rich in non-condensable combustible gas, and is discharged through the top of the gasification section together with the gasified coal gas generated in the gasification section; ② The other path of the coal gas enters the indirect cooler for cooling treatment, and the coal gas temperature drops to 35-45℃, and then the coal gas enters the droplet collector, and the mechanical water droplets carried in the coal gas are captured and supplied to the gas users.

7. The coal tar in-situ high-temperature catalytic cracking gasifier process according to claim 6, characterized in that: By tracking the temperature of the distillation gas exported from the distillation section, the flow rate of the backfired gas is automatically adjusted by PLC control to ensure that the temperature of the distillation gas exported from the top of the distillation section is maintained at 450℃-550℃.

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