A separation and purification system and method for coal-to-hydrogen shift gas.

Abstract

This invention provides a separation and purification system and method for coal-to-hydrogen conversion gas, belonging to the field of low-carbon energy and environmental protection technology. The system includes a decarbonization tower, a purification tower, a compressor, a cooler, a desulfurization tower, a gas-liquid separator, a slurry pump, a filter, a filtrate pump, a dehydration tower, a distillation tower, a condenser, a reboiler, a pretreatment unit, and a membrane separator. This invention utilizes adsorption, catalysis, distillation, and membrane separation technologies to perform decarbonization, desulfurization, dehydration, separation, and purification, producing hydrogen, industrial-grade carbon dioxide, and sulfur that meet the standards of refinery hydrogenation processes. This improves the recovery rate of hydrogen and carbon dioxide, reduces greenhouse gas emissions, and enhances overall resource utilization efficiency, resulting in significant economic, environmental, and social benefits.

Description

Technical Field

[0001] This invention belongs to the field of low-carbon energy and environmental protection technology, and more specifically, relates to a separation and purification system and method for coal-to-hydrogen conversion gas. Background Technology

[0002] Using coal as a raw material to produce hydrogen is a low-cost hydrogen production technology. However, the process generates a large amount of carbon dioxide as a byproduct. Carbon dioxide is both a greenhouse gas and a chemical feedstock; its recovery and reuse can reduce greenhouse gas emissions and improve resource utilization. A small amount of hydrogen sulfide is also produced during hydrogen production, requiring desulfurization to avoid environmental pollution. Current separation and purification technologies typically employ pressure swing adsorption (PSA) to separate hydrogen and low-temperature methanol washing, PSA, or distillation to separate carbon dioxide. While these techniques can recover most of the hydrogen and carbon dioxide, the desorbed and released gases still contain significant amounts of hydrogen and carbon dioxide, indicating room for further reductions in carbon dioxide emissions and hydrogen recovery. Summary of the Invention

[0003] The purpose of this invention is to overcome the shortcomings of the prior art and provide a separation and purification system and method for coal-to-hydrogen conversion gas.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A separation and purification system for coal-to-hydrogen conversion gas includes a decarbonization tower 1, a purification tower 2, a compressor 3, a cooler 4, a desulfurization tower 5, a compressor 6, a cooler 7, a gas-liquid separator 8, a slurry pump 9, a filter 10, a filtrate pump 11, a dehydration tower 12, a distillation tower 13, a condenser 14, a reboiler 15, a pretreatment unit 16, a membrane separator 17, a compressor 18, and a cooler 19; specifically as follows:

[0006] The inlet of the decarbonization tower 1 is fed with coal-to-hydrogen conversion gas S-1. The two outlets of the decarbonization tower 1 are connected to the inlet of the purification tower 2 and the bottom inlet of the desulfurization tower (5), respectively. The outlet of the purification tower 2 is connected to the hydrogen S-4 user and the inlet of the compressor 3, respectively. The outlet of the compressor 3 is connected to the shell inlet of the cooler 4. The shell outlet of the cooler 3 is connected to the inlet of the pretreatment unit 16. The top outlet of the desulfurization tower (5) is connected to the inlet of the compressor 6. The outlet of the compressor 6 is connected to the shell inlet of the cooler 7. The shell outlet of the cooler 7 is connected to the inlet of the gas-liquid separator 8. The bottom outlet of the gas-liquid separator 8 is connected to the top inlet of the desulfurization tower 5. The top outlet of the gas-liquid separator 8 is connected to the inlet of the dehydration tower 12. The outlet of the dehydration tower 12 is connected to the inlet of the distillation tower 13 and the inlet of the compressor 6, respectively. The bottom outlet of the desulfurization tower (5) is connected to the inlet of the slurry pump 9. The 9th port is connected to the inlet of the filter 10; the outlet of the filter 10 is connected to the inlet of the filtrate pump 11 and the sulfur S-19 storage device; the outlet of the filtrate pump 11 is connected to the top inlet of the desulfurization tower 5; the top outlet of the distillation tower 13 is connected to the inlet of the condenser 14; the outlet of the condenser 14 is connected to the inlet of the pretreatment unit 16; the permeate side outlet of the two-stage membrane separator 17 is connected to the fuel gas pipeline; the bottom outlet of the distillation tower 13 is connected to the... The reboiler 15 has an inlet and a liquid carbon dioxide S-22 storage tank; the outlet of the reboiler 15 is connected to the bottom inlet of the distillation column 13; the outlet of the pretreatment unit 16 is connected to the inlet of the membrane separator 17; the permeate side outlet of the membrane separator 17 is connected to the fuel gas S-24 user; the permeate side outlet of the membrane separator 17 is connected to the inlet of the compressor 18, the outlet of the compressor 18 is connected to the inlet of the cooler 19, and the outlet of the cooler 19 is connected to the inlet of the decarbonization column 1.

[0007] Furthermore, the coal-to-hydrogen shift gas comprises six parts: carbon dioxide, hydrogen, a mixture of carbon monoxide, nitrogen, and methane, hydrogen sulfide, and saturated water. Calculated with the total volume of the coal-to-hydrogen shift gas at 100%, the volume fractions of each part are as follows: carbon dioxide 22-60%, hydrogen 32-70%, the mixture of carbon monoxide, nitrogen, and methane 7%, and hydrogen sulfide less than or equal to 1%.

[0008] A method for separating and purifying coal-to-hydrogen shift gas, based on the above-mentioned separation and purification device, includes the following steps:

[0009] Step 1: The coal-to-hydrogen conversion gas S-1 and the returned permeate gas S-27 are mixed and then enter the decarbonization tower 1. Under the action of the adsorbent in the decarbonization tower 1, most of the carbon dioxide, almost all of the hydrogen sulfide and water, and a small amount of nitrogen, carbon monoxide, hydrogen and methane are adsorbed onto the adsorbent, and the hydrogen concentration is increased, resulting in decarbonized gas S-2. After the adsorbent in the decarbonization tower 1 is regenerated, carbon dioxide and other gases are released from the adsorbent, resulting in decarbonized desorption gas S-3.

[0010] Step 2: Decarbonized gas S-2 enters purification tower 2. Under the action of the adsorbent in purification tower 2, carbon dioxide, hydrogen sulfide, water, nitrogen, carbon monoxide, methane and a small amount of hydrogen are adsorbed onto the adsorbent to obtain hydrogen gas S-4, which is sent to the user. After the adsorbent in purification tower 2 is regenerated, carbon dioxide and other gases are released from the adsorbent to obtain purified desorbed gas S-5.

[0011] Step 3: Decarbonization desorption gas S-3 enters the desulfurization tower 5 from the bottom and comes into countercurrent contact with the sprayed water. Under the action of the desulfurizing agent, hydrogen sulfide is converted into sulfur, and sulfur is removed from the gas, resulting in desulfurization desorption gas S-9. After being pressurized by compressor 6 and cooled by cooler 7, the gaseous water in desulfurization desorption gas S-9 becomes liquid and enters gas-liquid separator 8 for gas-liquid separation. The liquid water S-14 coming out from the bottom of gas-liquid separator 8 is returned to desulfurization tower 5 and used as spray water; the gas coming out from the top of gas-liquid separator 8 enters the dehydration process. In tower 12, water is removed from the gas by the adsorbent, resulting in dehydrated desorbed gas S-15. After regeneration, water is released from the adsorbent, resulting in dehydrated regenerated gas S-16, which returns to the inlet of compressor 6. The sulfur generated in desulfurization tower 5 is carried away by spray water, forming sulfur slurry S-10, which is sent to filter 10 by slurry pump 9. After filtration, sulfur S-19 is obtained and sent to storage equipment. The remaining filtrate S-18 in filter 10 is sent to desulfurization tower 5 by filtrate pump 11 and used as spray water.

[0012] The desulfurization reaction in step 3 consists of an absorption reaction and a regeneration reaction. The specific principle and process are as follows:

[0013] 1) Overall desulfurization reaction

[0014] H₂S + 1 / 2O₂ → H₂O + S

[0015] 2) Absorption reaction

[0016] Absorption of gases in water

[0017] H₂S (gas) + H₂O (liquid) ⇌ H₂S (liquid) + H₂O (liquid)

[0018] ionization

[0019] H2S (liquid) ←→ H + +HS-

[0020] Oxidized by ferric ions

[0021] 2HS - +2Fe +++ →HS - +2Fe ++ +H + +S 0

[0022] Overall absorption reaction

[0023] H2S(gas) + 2Fe +++ →2Fe ++ +2H + +S 0

[0024] 3) Regeneration reaction

[0025] absorb

[0026] H₂O (liquid) + 1 / 2 O₂ (gas) → H₂O (liquid) + 1 / 2 O₂ (liquid)

[0027] Regeneration of ferrous ions

[0028] 1 / 2O2(liquid) + H2O(liquid) + 2Fe ++ →2Fe +++ +2OH -

[0029] Overall regeneration reaction

[0030] 1 / 2O2 (gas) + H2O (liquid) + 2Fe ++ →2Fe +++ +2OH -

[0031] Step 4: Dehydrated and desorbed gas S-15 enters distillation column 13. After distillation separation, most of the carbon dioxide becomes liquid. Liquid carbon dioxide S-22 is obtained at the bottom of the column and sent to the storage tank. Non-condensable gas S-21 is obtained at the top of the column.

[0032] Step 5: The purified desorbed gas S-5 is heated by compressor 3 and cooled by cooler 4, then mixed with non-condensable gas S-21 and enters pretreatment unit 16. After pretreatment, it enters membrane separator 17. Hydrogen and carbon dioxide gases permeate preferentially compared with carbon monoxide and methane gases. Hydrogen and carbon dioxide are enriched into permeate gas S-25 on the permeate side of membrane separator 17. Permeate gas S-25 is pressurized by compressor 18 and cooled by cooler 19, then mixed with coal-to-hydrogen conversion gas S-1 and returned to decarbonization tower 1. Hydrogen and carbon dioxide are used as fuel gas S-24 on the residual side of membrane separator 17.

[0033] Furthermore, in step 1, two or more decarbonization towers 1 are set up, using a pressure reduction regeneration method, and are filled with adsorbent, which is one or more of alumina, activated carbon, silica gel and molecular sieve.

[0034] Furthermore, in step 2, two or more purification towers 1 are set up, using a pressure reduction regeneration method, and are filled with adsorbents, which are one or more of alumina, activated carbon, silica gel and molecular sieves.

[0035] Furthermore, in step 3, the decarbonized desorbed gas S-3 comes into countercurrent contact with the spray water, and the desulfurization tower 5 is set up in more than 2 units, which are regenerated by air circulation S-8 and filled with iron oxide desulfurizing agent.

[0036] Furthermore, in step 4, two or more dehydration towers 12 are installed, using a pressure reduction regeneration method, and are filled with adsorbents, which are one or more of alumina, activated carbon, silica gel and molecular sieve.

[0037] Furthermore, the pretreatment unit 16 in step 5 is a liquid separator, a heat exchanger, a precision filter, and a demister.

[0038] Furthermore, in step 5, the low-pressure side outlet of the membrane separator 17 is the permeate side, and the high-pressure side outlet is the osmosis side. The membrane material used is a central fiber membrane, a flat sheet membrane, or a spiral wound membrane.

[0039] Furthermore, the central control fiber membrane, flat sheet membrane, or spiral wound membrane is an organic membrane, inorganic membrane, composite membrane, or mixed matrix membrane.

[0040] Advantages and beneficial effects of the present invention:

[0041] This invention utilizes adsorption, catalysis, distillation, and membrane separation technologies to decarbonize, desulfurize, dehydrate, separate, and purify hydrogen, industrial-grade carbon dioxide, and sulfur, producing hydrogen, industrial-grade carbon dioxide, and sulfur that meet the standards of refinery hydrogenation processes. This improves the recovery rates of hydrogen and carbon dioxide (hydrogen recovery rate can reach over 96%, and carbon dioxide recovery rate can reach over 97%), reduces greenhouse gases, and enhances overall resource utilization efficiency, resulting in significant economic, environmental, and social benefits. Attached Figure Description

[0042] Figure 1 This is a flowchart of a separation and purification system and method for coal-to-hydrogen shift gas proposed in this invention;

[0043] In the diagram: 1. Decarbonization tower; 2. Purification tower; 3. Compressor; 4. Cooler; 5. Desulfurization tower; 6. Compressor; 7. Cooler; 8. Gas-liquid separator; 9. Slurry pump; 10. Filter; 11. Filtrate pump; 12. Dehydration tower; 13. Distillation tower; 14. Condenser; 15. Reboiler; 16. Pretreatment unit; 17. Membrane separator; 18. Compressor; 19. Cooler;

[0044] S-1 Coal-to-hydrogen conversion gas; S-2 Decarbonized gas; S-3 Decarbonized desorbed gas; S-4 Hydrogen; S-5 Purified desorbed gas; S-8 Air; S-9 Desulfurized desorbed gas; S-10 Sulfur slurry; S-14 Liquid water; S-15 Dehydration desorbed gas; S-16 Dehydration regeneration gas; S-18 Filtrate; S-19 Sulfur; S-21 Non-condensable gas; S-22 Liquid carbon dioxide; S-24 Fuel gas; S-25 Permeate gas; S-27 Returned permeate gas. Detailed Implementation

[0045] To facilitate understanding of this application, a more complete description will be provided below with reference to the accompanying drawings. Preferred embodiments of this application are shown in the drawings. However, this application can be implemented in many different forms and is not limited to the embodiments described herein. Rather, these embodiments are provided to provide a more thorough and complete understanding of the disclosure of this application.

[0046] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the specification of this application is for the purpose of describing particular embodiments only and is not intended to be limiting of this application.

[0047] Example

[0048] like Figure 1 As shown.

[0049] This embodiment discloses a separation and purification system and method for coal-to-hydrogen shift gas, used for the separation and purification of shift gas from coal to hydrogen production. The shift gas composition in this embodiment is: 40.36% carbon dioxide (volume fraction), 52.50% hydrogen (volume fraction), 6.11% carbon monoxide + nitrogen + methane (volume fraction), 0.44% hydrogen sulfide (volume fraction), and saturated water. Using the technical solution of this invention, hydrogen with a concentration of over 99.9 mol%, industrial-grade carbon dioxide with a concentration of over 99.5 mol%, and sulfur are produced, meeting the standards of refinery hydrotreating processes. The hydrogen recovery rate is 97%, and the carbon dioxide recovery rate is 98%.

[0050] In this embodiment, the separation and purification method for coal-to-hydrogen conversion gas is as follows:

[0051] Step 1: After the shift gas S-1 is mixed with the return permeate gas S-27, it enters the decarbonization tower 1. Under the action of the adsorbent, most of the carbon dioxide, almost all of the hydrogen sulfide and water, and a small amount of nitrogen, carbon monoxide, hydrogen and methane are adsorbed onto the adsorbent. The hydrogen concentration is increased, and decarbonization gas S-2 is obtained. After the adsorbent is regenerated, carbon dioxide and other gases are released from the adsorbent, and decarbonization desorption gas S-3 is obtained.

[0052] Step 2: Decarbonized gas S-2 enters purification tower 2. Under the action of the adsorbent, carbon dioxide, hydrogen sulfide, water, nitrogen, carbon monoxide, methane and a small amount of hydrogen are adsorbed onto the adsorbent to obtain hydrogen gas S-4 with a concentration of more than 99.9 mol%, which is sent to the user. After the adsorbent is regenerated, carbon dioxide and other gases are released from the adsorbent to obtain purified desorbed gas S-5.

[0053] Step 3: Decarbonized desorbed gas S-3 enters desulfurization tower 5 from the bottom and comes into countercurrent contact with the sprayed water. Under the action of the desulfurizing agent, hydrogen sulfide is converted into sulfur, and sulfur is removed from the gas, yielding desulfurized desorbed gas S-9. This gas is then pressurized by compressor 6 and cooled by cooler 7, causing the gaseous water in the gas to liquefy. It then enters gas-liquid separator 8 for gas-liquid separation. The liquid water S-14 exiting from the bottom of the separator returns to desulfurization tower 5 as spray water. The gas exiting from the top of the separator enters dehydration tower 12, where it is further dehydrated by the adsorbent. The function is to remove water from the gas to obtain dehydrated desorbed gas S-15. After the adsorbent is regenerated, water is released from the adsorbent to obtain dehydrated regenerated gas S-16, which is returned to the inlet of compressor 6. The sulfur generated in desulfurization tower 5 is carried away by spray water to form sulfur slurry S-10, which is sent to filter 10 through slurry pump 9. After filtration, sulfur S-19 is obtained and sent to storage equipment. The remaining filtrate S-18 is sent to desulfurization tower 5 through filtrate pump 11 and used as spray water.

[0054] Step 4: Dehydrated and desorbed gas S-15 enters distillation column 13. After distillation separation, most of the carbon dioxide becomes liquid. Liquid carbon dioxide S-22 with a concentration of more than 99.5 mol% is obtained at the bottom of the column and sent to the storage tank. Non-condensable gas S-21 is obtained at the top of the column.

[0055] Step 5: After the purified desorbed gas S-5 is heated by compressor 3 and cooled by cooler 4, it is mixed with non-condensable gas S-21 and enters pretreatment unit 16. After pretreatment, it enters membrane separator 17. Hydrogen and carbon dioxide gases permeate preferentially than carbon monoxide and methane gases. Hydrogen and carbon dioxide are enriched on the permeate side of membrane separator 17. The permeate gas S-25 is pressurized by compressor 18 and cooled by cooler 19. It is mixed with shift gas S-1 and returned to decarbonization tower 1. Fuel gas S-24 is obtained on the permeate side of membrane separator 17 and used as fuel.

[0056] In this embodiment, the separation and purification system for coal-to-hydrogen conversion gas includes a decarbonization tower 1, a purification tower 2, a compressor 3, a cooler 4, a desulfurization tower 5, a compressor 6, a cooler 7, a gas-liquid separator 8, a slurry pump 9, a filter 10, a filtrate pump 11, a dehydration tower 12, a distillation tower 13, a condenser 14, a reboiler 15, a pretreatment unit 16, a membrane separator 17, a compressor 18, and a cooler 19.

[0057] The inlet of the decarbonization tower 1 is supplied with a shift gas S-1. The two outlets of the decarbonization tower 1 are connected to the inlet of the purification tower 2 and the bottom inlet of the desulfurization tower (5), respectively. The outlet of the purification tower 2 is connected to the hydrogen S-4 user and the inlet of the compressor 3, respectively. The outlet of the compressor 3 is connected to the shell inlet of the cooler 4. The shell outlet of the cooler 3 is connected to the inlet of the pretreatment unit 16. The top outlet of the desulfurization tower (5) is connected to the inlet of the compressor 6. The outlet of the compressor 6 is connected to the shell inlet of the cooler 7. The shell outlet of the cooler 7 is connected to the inlet of the gas-liquid separator 8. The bottom outlet of the gas-liquid separator 8 is connected to the top inlet of the desulfurization tower 5. The top outlet of the gas-liquid separator 8 is connected to the inlet of the dehydration tower 12. The outlet of the dehydration tower 12 is connected to the inlet of the distillation tower 13 and the inlet of the compressor 6, respectively. The bottom outlet of the desulfurization tower (5) is connected to the inlet of the slurry pump 9. The filter 10 is connected to its inlet end; the filter 10 is connected to its outlet end to the inlet end of the filtrate pump 11 and the sulfur S-19 storage device; the filtrate pump 11 is connected to the top inlet end of the desulfurization tower 5; the distillation tower 13 is connected to its top outlet end to the inlet end of the condenser 14; the condenser 14 is connected to its outlet end to the inlet end of the pretreatment unit 16; the two-stage membrane separator 15 is connected to its permeate side outlet end to the fuel gas pipeline; the distillation tower 13 is connected to its bottom outlet end to the inlet end of the reboiler 15 and the liquid carbon dioxide S-22 storage tank; the reboiler 15 is connected to its bottom inlet end; the pretreatment unit 16 is connected to its outlet end to the inlet end of the membrane separator 17; the membrane separator 17 is connected to its permeate side outlet end to the fuel gas S-24 user; the membrane separator 17 is connected to its permeate side outlet end to the inlet end of the compressor 18; the compressor 18 is connected to its outlet end to the inlet end of the cooler 19; and the cooler 19 is connected to the inlet end of the decarbonization tower 1.

[0058] The above-described embodiments are merely illustrative of the implementation methods of the present invention, but should not be construed as limiting the scope of the present invention. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these modifications and improvements all fall within the protection scope of the present invention.

Claims

1. A separation and purification system for coal-to-hydrogen shift gas, characterized in that, The separation and purification system includes a decarbonization tower (1), a purification tower (2), a compressor (3), a cooler (4), a desulfurization tower (5), a compressor (6), a cooler (7), a gas-liquid separator (8), a slurry pump (9), a filter (10), a filtrate pump (11), a dehydration tower (12), a distillation tower (13), a condenser (14), a reboiler (15), a pretreatment unit (16), a membrane separator (17), a compressor (18), and a cooler (19); specifically as follows: The inlet of the decarbonization tower (1) is fed with coal-to-hydrogen conversion gas (S-1). The two outlets of the decarbonization tower (1) are connected to the inlet of the purification tower (2) and the bottom inlet of the desulfurization tower (5), respectively. The outlet of the purification tower (2) is connected to the hydrogen (S-4) user and the inlet of the compressor (3), respectively. The outlet of the compressor (3) is connected to the shell inlet of the cooler (4). The shell outlet of the cooler (4) is connected to the inlet of the pretreatment unit (16). The top outlet of the desulfurization tower (5) is connected to the compressor ( 6) Inlet end; the outlet end of the compressor (6) is connected to the inlet end of the shell of the cooler (7); the outlet end of the shell of the cooler (7) is connected to the inlet end of the gas-liquid separator (8); the bottom outlet end of the gas-liquid separator (8) is connected to the top inlet end of the desulfurization tower (5); the top outlet end of the gas-liquid separator (8) is connected to the inlet end of the dehydration tower (12); the outlet end of the dehydration tower (12) is connected to the inlet end of the distillation tower (13) and the inlet end of the compressor (6) respectively; the bottom outlet end of the desulfurization tower (5) is connected to the slurry pump (9). The inlet end of the slurry pump (9) is connected to the inlet end of the filter (10); the outlet end of the filter (10) is connected to the inlet end of the filtrate pump (11) and the sulfur (S-19) storage device respectively; the outlet end of the filtrate pump (11) is connected to the top inlet end of the desulfurization tower (5); the top outlet end of the distillation tower (13) is connected to the inlet end of the condenser (14); the outlet end of the condenser (14) is connected to the inlet end of the pretreatment unit (16); the bottom outlet of the distillation tower (13) is connected to the inlet end of the reboiler (15) respectively. And a liquid carbon dioxide (S-22) storage tank; the outlet end of the reboiler (15) is connected to the bottom inlet end of the distillation column (13); the outlet end of the pretreatment unit (16) is connected to the inlet end of the membrane separator (17); the permeate side outlet of the membrane separator (17) is connected to the fuel gas (S-24) user; the permeate side outlet end of the membrane separator (17) is connected to the inlet end of the compressor (18), the outlet end of the compressor (18) is connected to the inlet end of the cooler (19), and the outlet end of the cooler (19) is connected to the inlet of the decarbonization tower (1).

2. The separation and purification system for coal-to-hydrogen shift gas according to claim 1, characterized in that, The coal-to-hydrogen conversion gas comprises six parts: carbon dioxide, hydrogen, a mixture of carbon monoxide, nitrogen, and methane, hydrogen sulfide, and saturated water. Calculated as 100% of the total volume of the coal-to-hydrogen conversion gas, the volume fractions of each part are as follows: carbon dioxide 22-60%, hydrogen 32-70%, the mixture of carbon monoxide, nitrogen, and methane 7%, and hydrogen sulfide less than or equal to 1%.

3. A method for separating and purifying coal-to-hydrogen shift gas, characterized in that, The separation and purification method is implemented based on the separation and purification system described in claim 1 or 2, and the separation and purification method includes the following steps: Step 1: The coal-to-hydrogen conversion gas (S-1) and the returned permeate gas (S-27) are mixed and then enter the decarbonization tower (1). Under the action of the adsorbent in the decarbonization tower (1), most of the carbon dioxide, almost all of the hydrogen sulfide and water, and a small amount of nitrogen, carbon monoxide, hydrogen and methane are adsorbed onto the adsorbent, and the hydrogen concentration is increased, resulting in decarbonized gas (S-2). After the adsorbent in the decarbonization tower (1) is regenerated, carbon dioxide and other gases are released from the adsorbent, resulting in decarbonized desorbed gas (S-3). Step 2: The decarbonized gas (S-2) enters the purification tower (2). Under the action of the adsorbent in the purification tower (2), carbon dioxide, hydrogen sulfide, water, nitrogen, carbon monoxide, methane and a small amount of hydrogen are adsorbed onto the adsorbent to obtain hydrogen (S-4), which is sent to the user. After the adsorbent in the purification tower (2) is regenerated, carbon dioxide and other gases are released from the adsorbent to obtain purified desorbed gas (S-5). Step 3: The decarbonization desorption gas (S-3) enters the desulfurization tower (5) from the bottom and comes into countercurrent contact with the sprayed water. Under the action of the desulfurizing agent, hydrogen sulfide is converted into sulfur, and sulfur in the gas is removed to obtain desulfurization desorption gas (S-9). After being pressurized by the compressor (6) and cooled by the cooler (7), the gaseous water in the desulfurization desorption gas (S-9) becomes liquid and enters the gas-liquid separator (8) for gas-liquid separation. The liquid water (S-14) coming out from the bottom of the gas-liquid separator (8) is returned to the desulfurization tower (5) and used as spray water. The gas coming out from the top of the gas-liquid separator (8) enters the dehydration tower ( 12) Under the action of the adsorbent, water is removed from the gas to obtain dehydrated desorbed gas (S-15). After the adsorbent is regenerated, water is released from the adsorbent to obtain dehydrated regenerated gas (S-16). Before returning to the compressor (6) inlet, the sulfur generated in the desulfurization tower (5) is carried away by the spray water to form sulfur slurry (S-10), which is sent to the filter (10) by the slurry pump (9). After filtration, sulfur (S-19) is obtained and sent to the storage device. The remaining filtrate (S-18) of the filter (10) is sent to the desulfurization tower (5) by the filtrate pump (11) and used as spray water. Step 4: Dehydrated and desorbed gas (S-15) enters the distillation column (13). After distillation separation, most of the carbon dioxide becomes liquid. Liquid carbon dioxide (S-22) is obtained at the bottom of the column and sent to the storage tank. Non-condensable gas (S-21) is obtained at the top of the column. Step 5: The purified desorbed gas (S-5) is heated by the compressor (3) and cooled by the cooler (4), then mixed with the non-condensable gas (S-21) and enters the pretreatment unit (16). After pretreatment, it enters the membrane separator (17). Hydrogen and carbon dioxide gases pass through preferentially compared with carbon monoxide and methane gases. Hydrogen and carbon dioxide are enriched into permeate gas (S-25) on the permeate side of the membrane separator (17). The permeate gas (S-25) is pressurized by the compressor (18) and cooled by the cooler (19), then mixed with the coal-to-hydrogen conversion gas (S-1) and returned to the decarbonization tower (1). Hydrogen and carbon dioxide are used as fuel gas (S-24) on the residual side of the membrane separator (17).

4. The method for separating and purifying coal-to-hydrogen shift gas according to claim 3, characterized in that, In step 1, the decarbonization tower (1) is set up in two or more units, and adopts a pressure reduction regeneration method. The tower is filled with adsorbent, which is one or more of alumina, activated carbon, silica gel and molecular sieve.

5. The method for separating and purifying coal-to-hydrogen shift gas according to claim 3, characterized in that, In step 2, the purification tower (2) is set up in two or more units, and adopts a pressure reduction regeneration method. The internal adsorbent is filled with one or more of alumina, activated carbon, silica gel and molecular sieve.

6. The method for separating and purifying coal-to-hydrogen shift gas according to claim 3, characterized in that, In step 3, the decarbonized desorbed gas (S-3) comes into countercurrent contact with the spray water. Two or more desulfurization towers (5) are set up and regenerated by air circulation (S-8). The towers are filled with iron oxide desulfurizing agents.

7. The method for separating and purifying coal-to-hydrogen shift gas according to claim 3, characterized in that, In step 4, two or more dehydration towers (12) are set up, and a pressure reduction regeneration method is adopted. The towers are filled with adsorbents, which are one or more of alumina, activated carbon, silica gel and molecular sieve.

8. The method for separating and purifying coal-to-hydrogen shift gas according to claim 3, characterized in that, The pretreatment unit (16) in step 5 consists of a liquid separator, a heat exchanger, a precision filter, and a demister.

9. The method for separating and purifying coal-to-hydrogen shift gas according to claim 3, characterized in that, In step 5, the low-pressure side outlet of the membrane separator (17) is the permeate side, and the high-pressure side outlet is the osmotic side. The membrane material used is a hollow fiber membrane, a flat sheet membrane, or a spiral wound membrane.

10. The method for separating and purifying coal-to-hydrogen shift gas according to claim 9, characterized in that, The hollow fiber membrane, flat sheet membrane, or spiral wound membrane is an organic membrane, inorganic membrane, composite membrane, or mixed matrix membrane.

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