A device and method for efficient resource utilization of PSA tail gas by cryogenic utilization of liquefied hydrocarbons coupled with double membrane separation

Abstract

The present invention provides an apparatus and method for the efficient resource utilization of PSA tail gas by coupling cryogenic utilization of liquefied hydrocarbons with double-membrane separation. The PSA tail gas first passes through a PSA double-membrane separation device to obtain enriched H2, enriched CO2, and methane gases. The enriched H2 undergoes three-stage compression and cooling before entering a CO adsorption device to obtain high-purity H2. The resulting adsorbed tail gas returns to the PSA double-membrane separation device for further H2 separation. The enriched CO2 enters a compression and condensation device to obtain high-purity CO2 liquid. The unliquefied CO2 dry gas and methane gas are mixed and then enter a CO2 membrane separator for further CO2 separation. The CO2-enriched circulating gas obtained on the permeate side enters a compression and condensation device, while methane-rich fuel gas is obtained on the retentate side. By coupling cryogenic utilization of liquefied hydrocarbons with double-membrane separation, the present invention fully utilizes the refrigeration of liquefied hydrocarbons during heating and vaporization through heat integration, efficiently separating and obtaining high-purity H2 and CO2, and producing fuel gas as a byproduct. This creates economic, social, and environmental benefits for the utilization of PSA tail gas and liquefied hydrocarbon refrigeration.

Description

Technical Field

[0001] The present invention belongs to the field of petrochemical industry and relates to a device and method for efficiently resource-generating PSA tail gas by utilizing cryogenic utilization of liquefied hydrocarbon coupled with double membrane separation. Background Art

[0002] With the increasing demand for large-scale cryogenic liquefied hydrocarbon storage in industrial parks in recent years, various industrial concentration areas have considered setting up spherical tank areas for centralized storage of large quantities of ethylene, propylene, etc. These cryogenic liquefied hydrocarbons are similar to LNG. Before being supplied to various equipment areas, they need to go through processes such as heating and gasification, which releases a large amount of cold energy. Currently, this part of cold energy has not been reasonably utilized, resulting in a large amount of cold energy resources being wasted. Therefore, recovering this part of cold energy has strong economic, social and environmental benefits.

[0003] Currently, the cooling energy released by LNG vaporization is primarily used for cold energy generation (including direct expansion, secondary refrigerant, and combined methods), air separation, and refrigeration. However, the liquefaction temperature of LNG is approximately -162°C, far lower than that of liquefied hydrocarbons. Its cooling quality is superior to that of liquefied hydrocarbons. Therefore, compared with LNG, the cooling energy of liquefied hydrocarbons has certain limitations in air separation and ultra-low temperature refrigeration. It can only be used for the separation of easily liquefied gases such as CO2 and light hydrocarbons.

[0004] Fuel cells are a highly promising energy conversion method due to their high energy efficiency and zero emissions. However, the source of hydrogen (H2) is a key factor restricting the development of fuel cell technology. Although H2 can be produced through water electrolysis, it suffers from low energy efficiency and high energy consumption. Currently, hydrogen production from petrochemical products is the most economical method, with light hydrocarbon steam reforming (PSA) being the primary method. Using natural gas, dry gas, or naphtha as feedstock, H2 with 99.99% purity is achieved through feedstock pretreatment, conversion reactions, and pressure swing adsorption technology. However, this also produces PSA tail gas containing CO2, H2, CH4, and CO, which requires separation and utilization to improve energy efficiency and reduce carbon emissions.

[0005] The cold energy released by cryogenic liquefied hydrocarbons is used to liquefy CO2 and separate CO2 from PSA tail gas. This not only realizes the utilization of the cold energy of liquefied hydrocarbons in the tank area, but also avoids problems such as absorbent entrainment and regeneration during the CO2 absorption process. However, directly using cold energy to liquefy CO2 in PSA tail gas will reduce the partial pressure of CO2 due to the presence of inert components (H2), requiring more cold energy for liquefaction, and also increasing equipment investment and operating costs. Therefore, it is necessary to first separate the inert components in PSA tail gas. Membrane separation is widely used in the field of gas separation due to its advantages such as room temperature operation and low energy consumption. By coupling membrane separation technology with liquefied hydrocarbon refrigeration, fuel cell-grade H2, liquid CO2 and fuel gas can be obtained, simultaneously realizing the comprehensive utilization of liquefied hydrocarbon cold energy and the separation and resource utilization of PSA tail gas. Summary of the Invention

[0006] The present invention provides an apparatus and method for efficiently utilizing PSA tail gas by cryogenically utilizing liquefied hydrocarbons coupled with double-membrane separation. This process integrates the combined operations of a PSA tail gas double-membrane separation unit, a CO2 membrane separation unit, a CO2 adsorption unit, and a CO2 compression and condensation unit to efficiently separate the PSA tail gas into fuel cell-grade high-purity H2, high-purity liquid CO2, and methane- and CO-rich fuel gas. Simultaneously, the CO2 compression and condensation unit and gas heat exchange utilize the cooling energy from the heating and vaporization of the liquefied hydrocarbons, achieving resource utilization of the PSA tail gas and the comprehensive utilization of the cooling energy from the liquefied hydrocarbons. Since there are many types of liquefied hydrocarbons, including ethylene, ethane, propylene, propane, butylene, and butane, the present invention uses the most common liquefied ethylene as an example for illustration.

[0007] PSA tail gas containing CO2, H2, CH4, and CO passes through a double-membrane separator for simultaneous bidirectional enrichment of H2 and CO2. The enriched H2, after compression and cooling, enters an adsorption unit to produce fuel cell-grade H2. The tail gas from the adsorption unit returns to the double-membrane separator for further H2 purification, thereby improving H2 recovery. The enriched CO2 is compressed and condensed to produce liquid CO2. The uncondensed CO2 dry gas is then heat-exchanged with the adsorbed tail gas from the CO adsorption unit, compressed and cooled, and then mixed with the retentate gas from the double-membrane separator before entering a CO2 membrane separator for further separation, thereby improving CO2 recovery. The enriched CO2 gas obtained on the permeate side of the CO2 membrane separator enters a compression and condensation unit for CO2 separation, while the retentate side produces fuel gas primarily composed of methane and CO.

[0008] The cooling capacity required by the present invention is entirely provided by the heating and vaporization of liquid ethylene. Specifically, the cooling capacity for liquefying CO2 from the CO2-enriched gas generated by the PSA double-membrane separator and the CO2 membrane separator is provided by the pressurized and heated liquid ethylene. The cooling capacity required for cooling the remaining compressed gas is provided by the vaporization of liquid ethylene from the spherical tank. The present invention can separate H2 and CO2 from PSA tail gas, producing fuel cell-grade H2, high-purity liquid CO2, and fuel gas primarily composed of methane and CO. It also fully utilizes the cooling capacity of the liquid ethylene heated and vaporized in the ethylene spherical tank area, achieving a cascaded utilization of cooling capacity from high-grade to low-grade, completing a closed-loop cooling cycle, and simultaneously achieving CO2 emission reduction and resource gas reuse, resulting in excellent economic and environmental benefits.

[0009] The present invention discloses a device for efficiently utilizing PSA tail gas for deep cold utilization of liquefied hydrocarbons coupled with double membrane separation, comprising a PSA double membrane separator, a CO2 membrane separator, a CO adsorption device, a CO2 compression and condensation device, and an H2 compression and cooling device. Specifically, the PSA tail gas pipeline is connected to the inlet of the PSA double membrane separator, the enriched H2 outlet of the PSA double membrane separator is connected to the inlet of the CO adsorption device after passing through the H2 compression and cooling device, the top outlet of the CO adsorption device is connected to a pure hydrogen storage tank, and the bottom outlet of the CO adsorption device is connected to the PSA double membrane separator after passing through the adsorption tail gas compressor and the adsorption tail gas cooler. A tail gas pipeline is connected, the enriched CO2 outlet of the PSA double membrane separator is connected to the inlet of the CO2 separator tank after passing through the CO2 compression and condensing device, the bottom outlet of the CO2 separator tank is connected to the liquid CO2 storage tank, the top outlet of the CO2 separator tank is connected to the adsorption tail gas cooler and the CO2 dry gas compression and cooling device in sequence, and then connected to the methane stream outlet pipeline of the PSA double membrane separator, the methane stream outlet pipeline is connected to the inlet of the CO2 membrane separator, the permeate side outlet of the CO2 membrane separator is connected to the CO2 compression and condensing device, and the retentate side outlet is connected to the fuel gas pipeline network.

[0010] Furthermore, the liquid ethylene from the tank truck is pressurized by an ethylene shielded pump and connected to the CO2 compression condensing device, and the cold energy released by the high-pressure ethylene during heating is used to provide cooling for the CO2 compression condensing device; the liquid ethylene spherical tank is connected to the H2 compression cooling device, and the cold energy released by the latent heat of vaporization of the liquid ethylene provides the required cooling energy for the H2 compression cooling device. The ethylene outlet of the H2 compression cooling device is connected to the CO2 dry gas cooler for heat exchange and then connected to the ethylene production gas device.

[0011] The specific process scheme of the present invention is as follows:

[0012] The PSA tail gas containing CO2, H2, CH4 and CO is pressurized to 2.5-4MPa after the pre-process, passes through the first demister and the first precision filter and enters the PSA tail gas double membrane separator, where it is bidirectionally enriched to obtain enriched H2 stream D and enriched CO2 stream B, and at the same time, methane stream C is obtained on the retentate side.

[0013] The enriched H2 stream D undergoes three stages of compression (a primary H2 compressor, a secondary H2 compressor, and a tertiary H2 compressor) and three stages of cooling (a primary H2 cooler, a secondary H2 cooler, and a tertiary H2 cooler) to produce a high-pressure H2 stream R with a pressure of 2.1 MPa and a temperature of 20-50°C. After passing through the adsorption bed, fuel cell-grade hydrogen K is obtained at the top of the CO adsorption device, and adsorption tail gas J is produced at the bottom. It then passes through the adsorption tail gas compressor and adsorption tail gas cooler to produce high-pressure adsorption tail gas Q with a pressure of 2.5-4 MPa and a temperature of 20-50°C. The high-pressure adsorption tail gas Q is then returned to the PSA double-membrane separation device for further separation to improve the H2 recovery rate.

[0014] The enriched CO2 stream B undergoes three-stage compression (a primary CO2 compressor, a secondary CO2 compressor, and a tertiary CO2 compressor) and three-stage condensation (a primary CO2 condenser, a secondary CO2 condenser, and a tertiary CO2 condenser) to ultimately produce a CO2 gas-liquid mixture G, which enters the CO2 separator. Liquid carbon dioxide H is produced at the bottom of the separator, with a temperature of -70 to -50°C and a pressure of 1.0 to 2.0 MPa. CO2 dry gas S is produced at the top of the separator, which, after heat exchange with the adsorbed tail gas J, is heated to -10 to 0°C before entering the primary CO2 dry gas compressor, the secondary CO2 dry gas compressor, and the CO2 dry gas cooler to ultimately produce high-pressure CO2 dry gas L with a pressure of 2.5 to 4 MPa and a temperature of 50°C. Subsequently, the high-pressure CO2 dry gas L and the methane stream C are mixed and enter the CO2 membrane separator to further separate the CO2. The circulating carbon dioxide E produced on the permeate side enters the CO2 compression and condensation device to liquefy into liquid CO2. The retentate side produces fuel gas F, the main components of which are methane, CO, and a small amount of H2.

[0015] In the CO2 compression and condensing unit, cooling capacity is provided by heating saturated liquid ethylene. In order to prevent the liquid ethylene from vaporizing during the heating process, the liquid ethylene needs to be pressurized first. The saturated liquid ethylene (-104°C, 101.8kPa) O from the tank truck is pressurized to 1.5-2.0MPa by an ethylene shielded pump, and then enters the three-stage CO2 condenser, the second-stage CO2 condenser, and the first-stage CO2 condenser in sequence to perform countercurrent heat exchange with CO2. Finally, high-pressure and high-temperature liquid ethylene P is obtained at the outlet of the first-stage CO2 condenser and is sent to the ethylene spherical tank at a temperature of -35--25°C. The cooling capacity consumed by the enriched H2 stream D during the compression and cooling process is provided by the vaporization of ethylene discharged from the ethylene spherical tank. The liquid ethylene M from the spherical tank enters the tertiary H2 cooler, the secondary H2 cooler and the primary H2 cooler in sequence, is reduced to 0.5-1.0 MPa by the pressure reducing valve, and then enters the CO2 dry gas cooler for heat exchange with the CO2 dry gas S. The obtained ethylene gas is sent into the device area through a pipeline for reaction.

[0016] The beneficial effects of the present invention are as follows: (1) the cooling capacity of the liquid ethylene heated and vaporized in the ethylene spherical tank area is fully utilized, the cascade utilization of cooling capacity from high grade to low grade is realized, the closed cycle utilization of cooling capacity is realized, and a large amount of cooling capacity is avoided from being wasted; (2) by coupling the PSA tail gas double membrane separation device, the CO2 membrane separation device, the CO adsorption device and the CO2 compression and condensation device, the cooling capacity loss of the inert components in the compression and condensation process and the additional cooling capacity caused by the low CO2 partial pressure are reduced, the cooling capacity utilization rate and separation efficiency are improved, and the energy consumption is reduced; (3) the coupling process can simultaneously obtain fuel cell grade high-purity H2, liquid high-purity CO2 and fuel gas, wherein the fuel cell grade high-purity H2 has a purity of 99.9999% (wherein the CO concentration is <0.2ppm) and a recovery rate of >90%, the liquid CO2 has a purity of >99% and a recovery rate of >90%, the CO2 content in the fuel gas is less than 10%, the calorific value of the fuel gas is improved, and the reuse of the PSA tail gas is realized, which has huge economic, social and environmental benefits. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 This is a process flow diagram of a device for efficient resource utilization of PSA tail gas by deep cooling of liquefied hydrocarbons coupled with double membrane separation.

[0018] In the figure: 1. First demister; 2. First precision filter; 3. PSA double membrane separator; 4. Second demister; 5. Second precision filter; 6. CO2 membrane separator; 7. First-stage CO2 compressor; 8. First-stage CO2 condenser; 9. Second-stage CO2 compressor; 10. Second-stage CO2 condenser; 11. Third-stage CO2 compressor; 12. Third-stage CO2 condenser; 13. CO2 separator; 14. Ethylene shielded pump; 15. First-stage H2 compressor; 16. First-stage H2 cooler; 17. Second-stage H2 compressor; 18. Second-stage H2 cooler; 19. Third-stage H2 compressor; 20. Third-stage H2 cooler; 21. CO adsorption device; 22. Adsorption tail Gas compressor; 23. Adsorption tail gas cooler; 24. First-stage CO2 dry gas compressor; 25. Second-stage CO2 dry gas compressor and; 26. CO2 dry gas cooler; 27. Pressure reducing valve; A. PSA tail gas; B. Enriched CO2 stream; C. Methane stream; D. Enriched H2 stream; E. Circulating CO2 stream; F. Fuel gas; G. Carbon dioxide gas-liquid mixture; H. Liquid CO2; J. Adsorption tail gas; K. Fuel cell grade H2; L. High-pressure CO2 dry gas; M. Spherical tank liquid ethylene; N. Low-temperature ethylene gas; O. Saturated liquid ethylene; P. High-pressure and high-temperature liquid ethylene; Q. High-pressure adsorption tail gas; R. High-pressure H2; S. CO2 dry gas; T. Ethylene production gas. DETAILED DESCRIPTION

[0019] The specific implementation methods of the present invention are described in detail below in conjunction with the technical solutions and the accompanying drawings. The following examples will further help to understand the present invention, but do not constitute a limitation to the contents of the present invention.

[0020] Example 1

[0021] Please combine the attached Figure 1In this embodiment, the PSA tail gas is primarily composed of H2, CO2, CO, and methane, with contents of 28.66 mol%, 48.56 mol%, 5.31 mol%, and 17.47 mol%, respectively. The pressure is 3 MPa and the temperature is 50°C. PSA tail gas A passes through a first demister 1 and a first precision filter 2 to remove moisture and impurities before entering a PSA double-membrane separator 3 for separation. H2-enriched stream D and CO2-enriched stream B are obtained on the H2 membrane side and the CO2 membrane side, respectively, while a methane-enriched stream C is obtained on the retentate side. The obtained enriched H2 stream D passes through the first-stage H2 compressor 15, the first-stage H2 cooler 16, the second-stage H2 compressor 17, the second-stage H2 cooler 18, the third-stage H2 compressor 19 and the third-stage H2 cooler 20 in sequence to obtain high-pressure H2R with a temperature of 50°C and a pressure of 2.1MPa. The stream for heat exchange with the enriched H2 stream D is the spherical tank liquid ethylene M coming out of the ethylene spherical tank, with a temperature of -30°C and a pressure of 1.94MPa. After three-stage countercurrent heat exchange, high-pressure ethylene gas with a temperature of 14.33°C and a pressure of 1.94MPa is obtained. After being reduced to 0.5MPa by the pressure reducing valve 27, low-temperature ethylene gas with a temperature of -3.9°C is obtained. After entering the CO adsorption unit 21, the high-pressure H2R is adsorbed by activated carbon, silica gel, and molecular sieves to produce high-purity fuel cell-grade H2K with a concentration of 99.9999%. The CO and CH4 contents are 0.13ppm and 0.16ppm, respectively, meeting the maximum CO and methane contents (0.2ppm) specified in GB / T 34872-2017. The hydrogen-containing adsorbed tail gas J generated at the bottom of the CO adsorption unit 21 passes through the adsorption tail gas compressor 22 and the adsorption tail gas cooler 23 to become high-pressure adsorption tail gas Q. After passing through the first demister 1 and the first precision filter 2, it returns to the PSA double-membrane separator 3 for further H2 separation, thereby improving the H2 recovery rate.

[0022] The enriched CO2 stream B produced by the PSA double-membrane separator 3 is cooled and compressed in sequence through the first-stage CO2 compressor 7, the first-stage CO2 condenser 8, the second-stage CO2 compressor 9, the second-stage CO2 condenser 10, the third-stage CO2 compressor 11 and the third-stage CO2 condenser 12 to obtain a CO2 gas-liquid mixture G with a temperature of -50°C and a pressure of 1.0 MPa. It then enters the CO2 separator 13 to obtain liquid CO2 H, in which the CO2 purity is 99.37 mol%. The obtained liquid CO2 is sent to the CO2 tank area through a pipeline for storage. The CO2 dry gas S generated at the top is heat exchanged with the adsorbed tail gas J generated by the CO adsorption device 21 and then enters the first-stage CO2 dry gas compressor 24 and the second-stage CO2 dry gas compressor 25 to be pressurized to 3.0 MPa. It then passes through the CO2 dry gas cooler 26 and exchanges heat with the low-temperature ethylene gas N after decompression to obtain high-pressure CO2 dry gas L with a temperature of 50°C. It is then mixed with the methane stream C on the retentate side of the PSA double membrane separator 3 and passes through the second demister 4 and the second precision filter 5 before entering the CO2 membrane separator 6 to further separate the CO2. The low-temperature ethylene gas N is heated to 20°C after heat exchange and is sent to the ethylene device through a pipeline as ethylene production gas T for reaction.

[0023] After the mixed gas enters the CO2 membrane separator 6, a circulating CO2 stream E is obtained on the permeate side. The circulating CO2 stream E is then mixed with the enriched CO2 stream B from the PSA double-membrane separator 3 and compressed and condensed to improve the CO2 recovery rate. The retentate side produces fuel gas F containing methane and CO. The methane and CO content exceeds 80%, which can be used as fuel gas or for further hydrogen production through the water-gas shift reaction. The cooling capacity required for the CO2 condensation process is provided by heating liquid ethylene. The atmospheric pressure saturated liquid ethylene O from the tank truck is first pressurized to 1.78 MPa by an ethylene shielded pump 14. It then passes through the tertiary CO2 condenser 12, the secondary CO2 condenser 10, and the primary CO2 condenser 8 in sequence for countercurrent heat exchange with CO2. High-pressure, high-temperature liquid ethylene P at -35.15°C is obtained at the outlet and then transported via a pipeline to an ethylene spherical tank for storage.

[0024] In this example, the resulting fuel cell-grade H2 had a purity of 99.9999% and an H2 recovery rate of 90.45%. The resulting liquid CO2 had a purity of 99.37% and a CO2 recovery rate of 94.99%. The fuel gas contained over 80% methane and CO, with small amounts of H2 and CO2. The table shows the operating parameters and compositions of the main streams in this example.

[0025]

[0026]

[0027] Example 2

[0028] Please combine the attached Figure 1 The composition of the PSA tail gas feed is 75 mol% H2, 18 mol% CO2, 3 mol% CO and 4 mol% CH4, the feed pressure is reduced to 2.5 MPa, and the feed saturated ethylene flow rate is 8.5m 3 / h, the liquid ethylene flow rate of the spherical tank is 4.5m 3 The process flow and other operating conditions are the same as those in Example 1.

[0029] In this implementation, the fuel cell-grade H2 produced had a purity of 99.99997% and a recovery rate of 94.21%. The liquid CO2 produced had a purity of 99.69% and a recovery rate of 96.45%. The combined CO and methane content of the fuel gas was 58.5%, and the H2 content was 36.01%. The presence of a small amount of CO2 increased the calorific value of the fuel gas. The main stream parameters and composition are shown in the table below.

[0030]

[0031]

[0032] In summary, the present invention realizes the separation of H2 and CO2 in PSA tail gas, obtains fuel cell-grade H2, high-purity liquid CO2, and fuel gas mainly composed of methane and CO, and at the same time fully utilizes the cooling capacity of the liquid ethylene in the ethylene spherical tank area during heating and gasification, realizes the cascade utilization of cooling capacity from high grade to low grade, completes the closed cycle utilization of cooling capacity, and realizes the reduction of CO2 emissions and the reuse of resource gas, with good economic and environmental benefits.

Claims

1. A device for efficient resource recovery of PSA tail gas by cryogenic utilization of liquefied hydrocarbons coupled with double membrane separation, characterized in that: The invention comprises a PSA double membrane separator (3), a CO2 membrane separator (6), a CO adsorption device (21), a CO2 compression condensation device and a H2 compression cooling device. Specifically, the PSA tail gas pipeline is connected to the inlet of the PSA double membrane separator (3), the enriched H2 outlet of the PSA double membrane separator (3) is connected to the inlet of the CO adsorption device (21) after passing through the H2 compression cooling device, the top outlet of the CO adsorption device (21) is connected to the hydrogen storage tank, and the bottom outlet of the CO adsorption device (21) is connected to the PSA tail gas pipeline after passing through the adsorption tail gas compressor (22) and the adsorption tail gas cooler (23). The enriched CO2 outlet of the separator (3) is connected to the inlet of the CO2 separator (13) after passing through the CO2 compression and condensation device, the bottom outlet of the CO2 separator (13) is connected to the liquid CO2 storage tank, the top outlet of the CO2 separator (13) is connected to the adsorption tail gas cooler (23) and the CO2 dry gas compression and cooling device in sequence, and then connected to the methane stream outlet pipeline of the PSA double membrane separator (3), the methane stream outlet pipeline is connected to the inlet of the CO2 membrane separator (6), the permeate side outlet of the CO2 membrane separator (6) is connected to the CO2 compression and condensation device, and the retentate side outlet is connected to the fuel gas pipeline network; The high-pressure saturated ethylene device is connected to the CO2 compression condensing device after passing through the ethylene shielded pump (14), and the cold energy released by the high-pressure ethylene temperature rise is used to provide cooling for the CO2 compression condensing device; the liquid ethylene spherical tank is connected to the H2 compression cooling device, and the cold energy released by the latent heat of liquid ethylene vaporization is used to provide the required cooling energy for the H2 compression cooling device. The ethylene outlet of the H2 compression cooling device is connected to the CO2 dry gas cooler (26) for heat exchange and then connected to the ethylene production gas device.

2. The device for efficient resource recovery of PSA tail gas by cryogenic utilization of liquefied hydrocarbon coupled with double membrane separation according to claim 1, characterized in that: The CO2 compression and condensing device comprises a first-stage CO2 compressor (7), a first-stage CO2 condenser (8), a second-stage CO2 compressor (9), a second-stage CO2 condenser (10), a third-stage CO2 compressor (11), and a third-stage CO2 condenser (12) connected in sequence, wherein the outlet of the third-stage CO2 condenser (12) is connected to the inlet of the CO2 liquid separation tank (13); the H2 compression and cooling device comprises a first-stage H2 compressor (15), a first-stage H2 cooler (16), a second-stage H2 compressor (17), a second-stage H2 cooler (18), a third-stage H2 compressor (19), and a third-stage H2 cooler (20) connected in sequence, wherein the outlet of the third-stage H2 cooler (20) is connected to the inlet of the CO adsorption device (21); the CO2 dry gas compression and cooling device comprises a first-stage CO2 dry gas compressor (24), a second-stage CO2 dry gas compressor (25), and a CO2 dry gas cooler (26) connected in sequence.

3. A process for utilizing the device for efficient resource utilization of PSA tail gas by using the liquefied hydrocarbon cryogenic utilization coupled with double membrane separation according to any one of claims 1-2, characterized in that: The process includes the following steps: (a) the PSA tail gas pressurized by the pre-process enters the PSA double membrane separator (3) for separation, and three gas streams, namely, an H2-enriched stream, a CO2-enriched stream and a methane stream, are obtained respectively; (b) the H2-enriched stream enters the CO adsorption device (21) after pressurization and cooling, and obtains fuel cell-grade high-purity hydrogen; the adsorbed tail gas of the CO adsorption device (21) is pressurized and heated, and then returns to the PSA double membrane separator (3) to further purify H2 and improve the H2 recovery rate; (c) the CO2-enriched stream enters the CO adsorption device (21) after pressurization and heating, and then returns to the PSA double membrane separator (3) to further purify H2 and improve the H2 recovery rate; After pressure cooling, it enters the CO2 separator (13) to obtain high-purity liquid CO2 and CO2 dry gas; after the CO2 dry gas is pressurized and heated, it is mixed with the methane stream and enters the CO2 membrane separator (6) to further purify the CO2, and an enriched CO2 circulating stream and a fuel gas stream are obtained on the permeate side and the retentate side respectively. The enriched CO2 circulating stream is sent to the CO2 compression and condensation device to further liquefy the CO2, thereby improving the CO2 recovery rate. The fuel gas stream is used as fuel or is further used to produce hydrogen through a water-gas change reaction or a methane steam reforming reaction.

4. The process according to claim 3, characterized in that: The PSA tail gas contains H2, CO2, methane and CO, wherein the CO content does not exceed 10 mol%.

5. The process according to claim 3, characterized in that: The process of the CO2 compression and condensation device is as follows: the CO2 enriched gas is compressed and cooled in two stages through a first-stage CO2 compressor (7), a first-stage CO2 condenser (8), a second-stage CO2 compressor (9) and a second-stage CO2 condenser (10) to obtain 0.5MPa, 40~50℃ compressed gas, which is further pressurized to 1.0~2.0MPa through a third-stage CO2 compressor (11), and then cooled to -70~-50℃ through a third-stage CO2 condenser (12) to obtain a CO2 gas-liquid mixture, which is then separated from the gas by a CO2 separator (13) to obtain a liquid CO2 product, which is then sent to a CO2 horizontal storage tank for storage, while the unliquefied CO2 dry gas returns to the CO2 membrane separator (6) to further separate the CO2, and then passes through the CO2 compression and condensation device again to separate the CO2, thereby further improving the CO2 recovery rate.

6. The process according to claim 3, characterized in that: The pressurized cooling process of the enriched H2 stream is as follows: the enriched H2 stream is pressurized and cooled in sequence through a first-stage H2 compressor (15), a first-stage H2 cooler (16), a second-stage H2 compressor (17), a second-stage H2 cooler (18), a third-stage H2 compressor (19) and a third-stage H2 cooler (20) to obtain high-pressure hydrogen, which then enters a CO adsorption device (21).

7. The process according to claim 3, characterized in that: The CO2 dry gas compression and cooling process includes: the CO2 dry gas from the CO2 separator (13) is first heated to -10~0°C by heat exchange with the adsorption tail gas generated by the CO adsorption device (21), and then enters the first-stage CO2 dry gas compressor (24) and the second-stage CO2 dry gas compressor (25), where the temperature is raised to 100~140°C. The CO2 dry gas then enters the CO2 dry gas cooler (26) for heat exchange to 50°C and enters the CO2 membrane separator (6) for further separation of CO2, thereby improving the CO2 recovery rate.

8. The process according to claim 3, characterized in that: The liquefied hydrocarbons utilized in the deep cooling of the liquefied hydrocarbons include but are not limited to one or more of ethylene, ethane, propylene, propane, butylene, and butane. The cold energy released by the heating and gasification of the liquefied hydrocarbons provides the required cold energy for the H2 compression cooling device and the CO2 compression condensing device.

9. The process according to claim 8, characterized in that: The cooling capacity required by the CO2 compression and condensing device comes from the cooling capacity released by the heating of high-pressure ethylene. Specifically, during the unloading process of the ethylene tank truck, the liquid ethylene is pressurized to 1.5~2.0MPa through the ethylene shielded pump (14), and then enters the third-stage CO2 condenser (12), the second-stage CO2 condenser (10) and the first-stage CO2 condenser (8) in sequence, which is used to reduce the compressor outlet gas temperature; at the same time, after the liquid ethylene is heated to -40~-30℃, it leaves the CO2 compression and condensing device and is sent to the ethylene spherical tank area for storage; The cooling capacity required by the H2 compression cooling device comes from the cooling capacity released by the latent heat of ethylene vaporization. Specifically, the saturated ethylene spherical tank needs to be vaporized into gas before being sent to the ethylene unit. Then it can be sent to the ethylene unit area for use. The cooling medium of the three-stage H2 cooler (20), the two-stage H2 cooler (18) and the one-stage H2 cooler (16) for heat exchange with the enriched H2 stream is liquid ethylene. The ethylene stored in the spherical tank enters the three-stage H2 cooler (20), the two-stage H2 cooler (18) and the one-stage H2 cooler (16) in turn for heating and vaporization, and then is reduced to 0.5~1MPa by a pressure reducing valve. At this time, the temperature of the ethylene gas drops to 10-20℃. After entering the CO2 dry gas cooler (26) for heat exchange, ethylene gas at room temperature is finally obtained and sent to the ethylene unit area through a pipeline to participate in the reaction.

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