Gas purification and separation method based on underground coal gasification

Abstract

The invention discloses a gas purification and separation method based on underground coal gasification. According to the technical scheme, the method includes the steps that raw gas from an underground coal gasification device firstly enters the initial purification process, specifically, the raw gas is subjected to heat exchange through a boiler to generate byproducts including low-pressure steam or hot water, tar and dust are removed through a scrubber tower and an electric precipitator, wet desulphurization and dry desulfurization are used for removing hydrogen sulfide and recycling sulphur, and debenzolization and naphthalene removal are conducted through temperature swing adsorption; then, the gas is compressed and enters the low-temperature separation process and the physical absorption separation process, and carbon dioxide is separated out; afterwards, the gas enters the cryogenic separation process, and methane is separated out; and finally, the remaining gas is carbon monoxide and hydrogen. According to the method, the gas separation procedure is short, the equipment investment cost is low, operation is easy, the separated-out carbon dioxide meets the requirement of serving as an oil-displacing agent for an oil field, the methane meets the requirement of natural gas at the national standard calorific value, meanwhile, the byproducts are the coal tar and the sulphur, and the carbon monoxide and the hydrogen can be used for combined heat and power generation.

Description

technical field

[0001] The invention relates to the technical field of coal chemical industry and clean coal, in particular to a method for separating CO from underground coal gasification gas 2 and CH 4 , A method and system for by-producing electricity, coal tar, sulfur, etc. at the same time. Background technique

[0002] Underground Coal Gasification (Underground Coal Gasification, hereinafter referred to as UCG) technology is the controlled combustion of underground coal. Combustible gas is generated through the thermal and chemical effects of coal, and new technologies for the comprehensive development of clean energy and the production of chemical raw materials. Its essence is to extract only the energy-containing components in coal, and leave pollutants such as ash and slag underground. Compared with traditional underground coal mining, UCG technology has the advantages of safety, high efficiency and less pollution.

[0003] Through UCG technology, fossil energy ...

Examples

Embodiment 1

[0052] The crude gas produced by the underground coal gasification unit has a temperature of 250°C and a pressure of 0.6MPa, and the processing capacity is equivalent to dry gas 100×10 4 N m 3 / d, the main composition of crude gas is shown in Table 1, and the composition of impurities in crude gas is shown in Table 2.

[0053] Table 1 Main components of crude gas

[0054]

[0055] Table 2 Composition of impurities in crude gas

[0056]

[0057] The treatment process is as follows: the crude gas is first heat-exchanged by the low-pressure boiler to 150°C to recover the preheated by-product low-pressure steam, and then enters the gas scrubber, where the gas is in countercurrent contact with cold water to cool the gas, and the water vapor in the crude gas Liquefaction with some impurities to remove most of the impurities such as water and tar, dust, thiophene, carbon disulfide, crude benzene, ammonia, etc. After passing through the scrubber, the gas enters the electrostat...

Embodiment 2

[0061] The crude gas produced by the underground coal gasification device has the same treatment capacity and crude gas composition as in Example 1. The treatment process is as follows: the crude gas first undergoes the initial purification process, is recovered and preheated through boiler heat exchange, dust and water are removed through the scrubber and electrostatic precipitator to recover tar, and H2 is removed through wet desulfurization and dry desulfurization. 2 S, recover sulfur 157Kg / h, control the gas outlet temperature in the initial purification process to 40°C, pressure 0.20Mpa, after the initial purification process, remove the moisture and impurities in the crude gas 15513Kg / h, at this time the tar and dust in the impurity content3 、H2S3 . The initially purified gas is compressed and cooled for gas-liquid separation to control CO 2 The cryogenic separation temperature is -35°C, and the CO 2 The separation effect is shown in Table 3.

[0062] Table 3 Effect of...

Embodiment 3

[0066] The crude gas produced by the underground coal gasification device has the same treatment capacity and crude gas composition as in Example 1. The treatment process is as follows: the crude gas first undergoes the initial purification process, is recovered and preheated through boiler heat exchange, dust and water are removed through the scrubber and electrostatic precipitator to recover tar, and H2 is removed through wet desulfurization and dry desulfurization. 2 S, recover sulfur 157Kg / h, control the gas outlet temperature in the initial purification process to 40°C, pressure 0.19Mpa, after the initial purification process, remove the moisture and impurities in the crude gas 15513Kg / h, at this time the tar and dust in the impurity content3 、H2S3 . The initially purified gas is compressed and cooled for gas-liquid separation to control CO 2 The cryogenic separation pressure is 5.5MPaG, and the CO 2 The separation effect is shown in Table 4.

[0067] Table 4 The pressu...

technical field

[0001] The invention relates to the technical field of coal chemical industry and clean coal, in particular to a method for separating CO from underground coal gasification gas 2 and CH 4 , A method and system for by-producing electricity, coal tar, sulfur, etc. at the same time. Background technique

[0002] Underground Coal Gasification (Underground Coal Gasification, hereinafter referred to as UCG) technology is the controlled combustion of underground coal. Combustible gas is generated through the thermal and chemical effects of coal, and new technologies for the comprehensive development of clean energy and the production of chemical raw materials. Its essence is to extract only the energy-containing components in coal, and leave pollutants such as ash and slag underground. Compared with traditional underground coal mining, UCG technology has the advantages of safety, high efficiency and less pollution.

[0003] Through UCG technology, fossil energy ...

Examples

Embodiment 1

[0052] The crude gas produced by the underground coal gasification unit has a temperature of 250°C and a pressure of 0.6MPa, and the processing capacity is equivalent to dry gas 100×10 4 N m 3 / d, the main composition of crude gas is shown in Table 1, and the composition of impurities in crude gas is shown in Table 2.

[0053] Table 1 Main components of crude gas

[0054]

[0055] Table 2 Composition of impurities in crude gas

[0056]

[0057] The treatment process is as follows: the crude gas is first heat-exchanged by the low-pressure boiler to 150°C to recover the preheated by-product low-pressure steam, and then enters the gas scrubber, where the gas is in countercurrent contact with cold water to cool the gas, and the water vapor in the crude gas Liquefaction with some impurities to remove most of the impurities such as water and tar, dust, thiophene, carbon disulfide, crude benzene, ammonia, etc. After passing through the scrubber, the gas enters the electrostat...

Embodiment 2

[0061] The crude gas produced by the underground coal gasification device has the same treatment capacity and crude gas composition as in Example 1. The treatment process is as follows: the crude gas first undergoes the initial purification process, is recovered and preheated through boiler heat exchange, dust and water are removed through the scrubber and electrostatic precipitator to recover tar, and H2 is removed through wet desulfurization and dry desulfurization. 2 S, recover sulfur 157Kg / h, control the gas outlet temperature in the initial purification process to 40°C, pressure 0.20Mpa, after the initial purification process, remove the moisture and impurities in the crude gas 15513Kg / h, at this time the tar and dust in the impurity content3 、H2S3 . The initially purified gas is compressed and cooled for gas-liquid separation to control CO 2 The cryogenic separation temperature is -35°C, and the CO 2 The separation effect is shown in Table 3.

[0062] Table 3 Effect of...

Embodiment 3

[0066] The crude gas produced by the underground coal gasification device has the same treatment capacity and crude gas composition as in Example 1. The treatment process is as follows: the crude gas first undergoes the initial purification process, is recovered and preheated through boiler heat exchange, dust and water are removed through the scrubber and electrostatic precipitator to recover tar, and H2 is removed through wet desulfurization and dry desulfurization. 2 S, recover sulfur 157Kg / h, control the gas outlet temperature in the initial purification process to 40°C, pressure 0.19Mpa, after the initial purification process, remove the moisture and impurities in the crude gas 15513Kg / h, at this time the tar and dust in the impurity content3 、H2S3 . The initially purified gas is compressed and cooled for gas-liquid separation to control CO 2 The cryogenic separation pressure is 5.5MPaG, and the CO 2 The separation effect is shown in Table 4.

[0067] Table 4 The pressu...

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