Variable-working-condition produced gas carbon dioxide trapping system and process method

Abstract

The invention belongs to the technical field of ground engineering CCUS, and particularly relates to a variable-working-condition produced gas carbon dioxide capturing system and a process method. The trapping system comprises an oilfield associated gas source outlet, a pressure swing adsorption compressor, a first-stage pressure swing adsorption unit, a second-stage pressure swing adsorption unit, a membrane separation unit and a vacuum pump, the preparation method comprises the following steps: performing primary pressure swing adsorption on CO2-containing mixed gas; then carrying out secondary pressure swing adsorption; and finally, performing membrane separation to obtain gas with carbon dioxide purity of more than or equal to 95%. The invention mainly solves the problem that the CO2 concentration and gas quantity in associated gas are changed by adopting a variable-working-condition produced gas carbon dioxide capture membrane and psa coupling process method, is high in applicability, adopts a pressure swing adsorption device at the front section, can reduce the maintenance work of the membrane, and can also be suitable for the change of gas quantity through series-parallel connection. The purification process is reduced, and the purposes of technology coupling, energy conservation, carbon reduction and green development are achieved.

Description

Technical Field

[0001] The present invention belongs to the technical field of CCUS in ground engineering, and specifically relates to a system and process for capturing carbon dioxide from produced gas under variable operating conditions. Background Art

[0002] As a large-scale greenhouse gas emission reduction technology, carbon dioxide capture, utilization and storage (CCUS) technology has been increasingly improving in scientific research and technological capabilities and levels.

[0003] At present, Xinjiang Oilfield has carried out industrial test projects of CO2 miscible drive in some blocks of oil reservoirs. How to capture CO2 is a direction that needs to be explored. The main methods currently used for CO2 capture are chemical absorption, physical absorption, pressure swing adsorption, low-temperature condensation and membrane separation. However, during the exploitation of the oilfield, the CO2 content changes greatly with the time of exploitation. The development process is divided into three stages: the first stage: the gas volume is small and the CO2 content concentration is low in the early stage of exploitation; the second stage: the gas volume is large and the CO2 content concentration is high in the middle stage of exploitation; the third stage: the gas volume is small and the CO2 content concentration is high in the late stage of exploitation. How to select appropriate processes and equipment solutions to solve the problem of low-concentration, medium-concentration and high-concentration carbon dioxide capture while the gas volume changes is a direction for saving energy.

[0004] For low-concentration CO2 in the early stage of mining, chemical absorption + thermal decomposition is often used for capture; its characteristics are high energy consumption, long process, large floor space, and relatively complex operation, which is suitable for large-scale carbon source capture; for medium and high-concentration CO2, membrane separation and PSA are often used, and its characteristics are that membrane separation is a rapidly developing CO2 separation technology. It is a newer physical separation method without phase change. It has obvious advantages such as low investment cost, simple operation, high separation efficiency, small floor space, low energy consumption, and environmental friendliness, which is suitable for small-scale carbon source capture. In terms of combined capture, gas membrane separation technology can be used in conjunction with other separation processes because of its advantages such as low operating difficulty and easy coupling with other separation technologies, thereby improving the separation effect.

[0005] Chinese invention patent application CN201710654278.4 discloses a method for removing CO2 from tail gas of hydrogen production conversion gas pressure swing adsorption process, where the PSA tail gas from the pressure swing adsorption device enters the membrane assembly for separation, CO2 is separated as permeate gas, and other components in the PSA tail gas leave the membrane assembly as retentate gas. This method can solve the problem of removing carbon dioxide from the pressure swing adsorption tail gas in the hydrogen production process, and the introduction of the membrane assembly can greatly simplify the process flow and operating costs while improving the process economy.

[0006] Chinese invention patent application CN202110954080.4 discloses a process and equipment for recovering light hydrocarbons and carbon dioxide from associated gas of oilfield drive. When the CO2 content of associated gas is 30% to 75%, the associated gas is first treated by a membrane separation device. After the membrane separation device treats the associated gas with a CO2 content of 71% to 92%, it enters a pressure swing adsorption device. Through selective adsorption by different types of adsorbents loaded in the adsorption tower, the analyzed gas is subjected to carbon dioxide content purity ≥ 95%, and is sent to a pressurized integrated device. After the gas discharged by the pressure swing adsorption flows back to the membrane separation system, the CO2 ≤ 5.0% of the natural gas on the non-permeable side of the membrane separation is directly sent to the gas pipeline network. The present invention relates to the field of oilfield carbon dioxide recovery technology. There is no waste gas emission in the entire process, and the environmental benefits are good. The membrane method + pressure swing adsorption method is used to separate the CO2 and dry gas in the associated gas of the oilfield. The whole adopts a skid-mounted mode, and the membrane separation skid is assembled by the provider. After the whole is transported to the construction unit for on-site installation, it can be debugged and produced.

[0007] The above patents have all explored CO2 recovery methods, but during the exploitation process of the oil field, the associated gas content and CO2 content concentration change significantly with the time of exploitation. It is impossible to use a set of capture technologies to solve the capture problem of different associated gas amounts and different CO2 concentrations. Therefore, how to establish a carbon dioxide capture process for produced gas using variable operating conditions to support the efficient development of CCUS demonstration areas is an issue that needs to be urgently addressed in this field. Summary of the invention

[0008] In view of the deficiencies of the above-mentioned prior art, the present invention aims to form a set of capture technology for different concentrations of carbon dioxide in oilfield associated gas throughout its life cycle, through secondary capture of a burner-coupled pressure swing adsorption and membrane separation combination, and at the same time using a carbon molecular sieve membrane prepared from a carboxylated polyimide with characteristics, to effectively recover CO2, so as to realize the equipment-coupled development of the CCUS industry chain.

[0009] In order to achieve the purpose of the present invention, the technical solution adopted is as follows:

[0010] A variable operating condition produced gas carbon dioxide capture system, the capture system comprising an oilfield associated gas source outlet, a pressure swing adsorption compressor, a primary pressure swing adsorption unit, a secondary pressure swing adsorption unit, a membrane separation unit and a vacuum pump; wherein a first valve is arranged between the oilfield associated gas inlet and the pressure swing adsorption compressor; a second valve is arranged between the pressure swing adsorption compressor and the bottom of the primary pressure swing adsorption unit, a sixth valve and a seventh valve are arranged in sequence between the top of the secondary pressure swing adsorption unit and the membrane separation unit, a fourth valve is arranged between the pipeline between the top of the secondary pressure swing adsorption unit and the sixth valve and the top of the primary pressure swing adsorption unit, a third valve is arranged between the pipeline between the top of the primary pressure swing adsorption unit and the fourth valve and the bottom of the secondary pressure swing adsorption unit, a fifth valve is arranged between the pipeline between the pressure swing adsorption compressor and the second valve and the pipeline between the bottom of the secondary pressure swing adsorption unit and the third valve, and an eighth valve is arranged between the membrane separation unit and the vacuum pump.

[0011] Preferably, in the first type, the outlet of the associated gas source of the oil field is a mixed gas containing 30%-60% CO2 and a gas volume of ≤50,000 cubic meters / day, and the method of using the capture system is: first open the first valve, the second valve, the third valve, the sixth valve, the seventh valve, and the eighth valve, close the fourth valve and the fifth valve, and pass the mixed gas into the pressure swing adsorption compressor, and then pass through the first pressure swing adsorption unit and the second pressure swing adsorption unit in sequence, and then pass through the membrane separation unit, and after passing through the vacuum pump, obtain carbon dioxide with a purity of ≥95%.

[0012] Preferably, in the second type, the outlet of the associated gas source of the oil field is a mixed gas containing ≥60% CO2 and a gas volume ≤50,000 cubic meters / day, and the method of using the capture system is: first open the first valve, the second valve, the fourth valve, the fifth valve, the sixth valve, the seventh valve, and the eighth valve, and close the third valve. The mixed gas first passes through the pressure swing adsorption compressor, and then is divided into a parallel primary pressure swing adsorption unit and a secondary pressure swing adsorption unit, and finally passes through a membrane separation unit, and after passing through a vacuum pump, a carbon dioxide with a purity of ≥95% is obtained.

[0013] Preferably, in the third type, the outlet of the associated gas source of the oil field is a mixed gas containing ≥60% CO2 and a gas volume ≥50,000 cubic meters / day, and the method of using the capture system is: first open the first valve, the fifth valve, the sixth valve, the seventh valve, and the eighth valve, and close the second valve, the third valve, and the fourth valve, and the mixed gas is introduced into the pressure swing adsorption compressor, and then passes through the secondary pressure swing adsorption unit, the membrane separation unit and the vacuum pump in sequence to obtain carbon dioxide with a purity of ≥95%.

[0014] Another object of the present invention is to provide a process for capturing carbon dioxide from produced gas under variable operating conditions, wherein the process adopts the above-mentioned capture system and comprises the following steps:

[0015] (1) subjecting the CO2-containing mixed gas to a first-stage pressure swing adsorption;

[0016] (2) performing secondary pressure swing adsorption;

[0017] (3) Perform membrane separation to obtain carbon dioxide gas with a purity of ≥95%.

[0018] Preferably, the membrane in step (3) is selected from a 6FBI / ZIF-8-based carbon molecular sieve membrane doped with ZIF-8.

[0019] Preferably, the CO2 concentration in step (1) is 30-60% and the gas volume is ≤50,000 cubic meters per day, and the process method adopts the first capture system mentioned above.

[0020] Preferably, in step (1), the concentration of CO2 in the mixed gas is ≥60% and the gas volume is ≤50,000 cubic meters per day, the primary pressure swing adsorption step is omitted, and the process method adopts the second capture system mentioned above.

[0021] Preferably, in step (1), the concentration of CO2 in the mixed gas is ≥60% and the gas volume is ≥50,000 cubic meters / day, the mixed gas is divided into two parts, one part is subjected to primary pressure swing adsorption to obtain gas A, and the other part is subjected to secondary pressure swing adsorption to obtain gas B, and gas A and gas B are separated by membrane together; the process method adopts the third capture system mentioned above.

[0022] Another object of the present invention is to provide an application of the above process method in capturing carbon dioxide from associated gas with different CO2 concentrations and gas volumes.

[0023] Compared with the prior art, the present invention has the following characteristics:

[0024] (1) The present invention adopts a variable working condition produced gas carbon dioxide capture membrane and a PSA coupling process method, which mainly solves the problem that the CO2 concentration and gas volume in the associated gas are changing, and has strong applicability. At the same time, the front stage adopts a pressure swing adsorption device, which can reduce the maintenance work of the membrane, and the series and parallel connection can also adapt to the change of gas volume. Reduce the purification process, achieve technical coupling, energy saving and carbon reduction, and green development.

[0025] (2) The process of the present invention is a combined capture process in which both the concentration and the amount of CO2 in the associated gas of the CO2 miscible flooding block can be changed;

[0026] (3) The present invention uses a 6FBI / ZIF-8-based carbon molecular sieve membrane doped with ZIF-8, which has a better separation effect than other carbon molecular sieve membranes and can recover CO2 to the greatest extent.

[0027] (4) The existing technology usually uses chemical absorption + thermal decomposition method to capture low-concentration CO2, which is characterized by high energy consumption, long process, large floor space, complex operation, and is suitable for large-scale carbon source capture; membrane separation and pressure swing adsorption are usually used to capture medium and high concentration CO2, which are characterized by short process, small floor space, simple operation, and are suitable for small-scale carbon source capture. The present invention aims to achieve carbon source capture in the CO2 mixed phase drive industrial test block. The block is characterized by a small-scale carbon source and the concentration and gas volume of CO2 change with the time of mining. The existing technology cannot solve the problem of carbon source capture at different concentrations by investing in one equipment. The present invention uses a variable operating condition produced gas carbon dioxide capture membrane and a PSA coupling process method to solve the problem of carbon source capture at different concentrations and gas volumes. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a process flow chart of the present invention;

[0029] Figure 2 The present invention is a variable operating condition produced gas carbon dioxide capture system; in the figure, 1, pressure swing adsorption compressor; 2-1, primary pressure swing adsorption unit; 2-2, secondary pressure swing adsorption unit; 3, membrane separation unit 4, vacuum pump; 5, oil field associated gas source outlet;

[0030] V1, the first valve; V2, the second valve; V3, the third valve; V4, the fourth valve; V5, the fifth valve; V6, the sixth valve, V7, the seventh valve, V8, the eighth valve. DETAILED DESCRIPTION

[0031] The present invention is further described below in conjunction with specific embodiments. The materials used in the following equipment are all commercially available conventional materials.

[0032] Example 1

[0033] The specific process flow chart of the present invention is shown in Figure 1 .

[0034] The present invention discloses a system for capturing carbon dioxide from produced gas under variable working conditions. Figure 2 .

[0035] The system includes an oilfield associated gas source outlet, a pressure swing adsorption compressor, a primary pressure swing adsorption unit, a secondary pressure swing adsorption unit, a membrane separation unit and a vacuum pump; wherein a first valve is arranged between the oilfield associated gas inlet and the pressure swing adsorption compressor; a second valve is arranged between the pressure swing adsorption compressor and the bottom of the primary pressure swing adsorption unit, a sixth valve and a seventh valve are arranged in sequence between the top of the secondary pressure swing adsorption unit and the membrane separation unit, a fourth valve is arranged between a pipeline between the top of the secondary pressure swing adsorption unit and the sixth valve and the top of the primary pressure swing adsorption unit, a third valve is arranged between a pipeline between the top of the primary pressure swing adsorption unit and the fourth valve and the bottom of the secondary pressure swing adsorption unit, a fifth valve is arranged between a pipeline between the pressure swing adsorption compressor and the second valve and a pipeline between the bottom of the secondary pressure swing adsorption unit and the third valve, and an eighth valve is arranged between the membrane separation unit and the vacuum pump.

[0036] Among them, the adsorption towers in the primary pressure swing adsorption unit and the secondary pressure swing adsorption unit are filled with conventional adsorbent MOFs materials;

[0037] The membrane separation unit is a 6FBI / ZIF-8 based carbon molecular sieve membrane separation device doped with ZIF-8, wherein the preparation method of ZIF-8 is as follows:

[0038] Weigh 3.3g of 2-methylimidazole and 1.5g of zinc nitrate hexahydrate and add them to 70ml of methanol. Use an oil bath to control the temperature of the zinc nitrate methanol solution at about 25°C. Add the imidazole solution to the zinc nitrate solution and stir. Observe that the solution gradually turns white, and then stir and synthesize for 24h. After the mixed solution is centrifuged and washed with methanol three times, the remaining methanol solvent is filtered off. After the powder is completely dried, it is placed in a vacuum oven at 80°C and dried for 12h to obtain a ZIF-8 sample.

[0039] The preparation method of 6FDA-BI polyimide is as follows:

[0040] 2-(4-aminophenyl)-5-aminobenzimidazole was added to a 100mL flask, followed by NMP (45mL), and after complete dissolution under N2 atmosphere, 6FDA (8.8848g, 0.02mol) was added at low temperature. The reaction mixture was stirred at room temperature for 24h to form the corresponding polyamic acid. Afterwards, 3-methylpyridine (1.9mL, 0.02mol) and acetic anhydride (18.9mL, 0.2mol) were added to the reaction mixture and stirred for 24h to induce complete imidization of polyamic acid to form polyimide. The polyimide was precipitated in methanol, washed, and then vacuum dried at 100°C for 24h to obtain 6FDA-BI polyimide.

[0041] The preparation method of 6FBI / ZIF-8 based carbon molecular sieve membrane is as follows:

[0042] 0.1 g of ZIF-8 was dispersed in DMAc (dimethylacetamide) and stirred overnight, and then the ZIF-8 solution was ultrasonically treated for 3 min to form a uniform suspension. The required amount of 6FDA-BI was dissolved in DMAc and then mixed with the ZIF-8 solution to obtain a dispersion. The prepared dispersion was stirred for 30 min and then ultrasonically treated for 3 min. The remaining 6FDA-BI was added to the above solution in three batches to obtain the desired mixed matrix membrane solution, and the stirring and ultrasonic treatment steps were repeated 3 times. Finally, the mixed solution was stirred overnight, and the solution was cast on a glass substrate using a scraper and dried in an oven at 60 ° C for 2-3 h. After the solvent was completely evaporated, the film was scraped off the glass plate, soaked in a methanol solution for 12 h, and then dried in a vacuum oven at 150 ° C for 12 h.

[0043] The 6FBI / ZIF-8 polymer was thermally cross-linked and then pyrolyzed at 550-580°C to obtain a 6FBI / ZIF-8 based carbon molecular sieve membrane.

[0044] The working principle is:

[0045] For a mixed gas containing 30%-60% CO2 and a low gas volume, first open the first valve, the second valve, the third valve, the sixth valve, the seventh valve, and the eighth valve, close the fourth valve and the fifth valve, and pass the mixed gas into a pressure swing adsorption compressor, and then pass through a primary pressure swing adsorption unit and a secondary pressure swing adsorption unit in sequence, and then pass through a membrane separation unit, and after passing through a vacuum pump, obtain carbon dioxide with a purity of ≥95%.

[0046] For the oilfield associated gas source outlet containing ≥60% CO2 and low gas volume mixed gas, the capture system is used as follows: first open the first valve, the second valve, the fourth valve, the fifth valve, the sixth valve, the seventh valve, and the eighth valve, and close the third valve. The mixed gas first passes through the pressure swing adsorption compressor, and then is divided and connected to the first-level pressure swing adsorption unit and the second-level pressure swing adsorption unit, and finally passes through the membrane separation unit and the vacuum pump to obtain carbon dioxide with a purity of ≥95%.

[0047] For the oilfield associated gas source outlet containing ≥60% CO2 and a high gas volume mixed gas, the capture system is used as follows: first open the first valve, the fifth valve, the sixth valve, the seventh valve, and the eighth valve, and close the second valve, the third valve, and the fourth valve. The mixed gas is introduced into the pressure swing adsorption compressor, and then passes through the secondary pressure swing adsorption unit, the membrane separation unit, and the vacuum pump in sequence to obtain carbon dioxide with a purity of ≥95%.

[0048] The following examples are directed to the geological prediction indicators of the industrialized experimental block of CO2 miscible flooding in Xinjiang Oilfield, where the CO2 content of the associated gas is 10.0-85.33%.

[0049] Example 2

[0050] For a mixed gas with low CO2 concentration (≥30%) and low gas volume (<50,000 cubic meters / day), the first valve, the second valve, the third valve, the sixth valve, the seventh valve, and the eighth valve are opened, and the fourth valve and the fifth valve are closed. First, the mixed gas passes through a primary pressure swing adsorption unit to adsorb and analyze the gas to obtain a carbon dioxide content purity (≥60%), and then passes through a secondary pressure swing adsorption unit to adsorb and analyze the gas to obtain a carbon dioxide content purity (≥85%), and finally is sent to a 6FBI / ZIF-8-based carbon molecular sieve membrane separation device with selective doping of ZIF-8, and the analyzed gas is separated to obtain high-purity carbon dioxide (content purity 99%).

[0051] Example 3

[0052] Open the first valve, the second valve, the fourth valve, the fifth valve, the sixth valve, the seventh valve, and the eighth valve, and close the third valve. Pass the medium-concentration CO2 (≥60%) mixed gas and low gas volume (<50,000 cubic meters / day) gas directly through the pressure swing adsorption compressor, and then divert it to the parallel primary pressure swing adsorption unit and the secondary pressure swing adsorption unit, and finally pass through the membrane separation unit and the vacuum pump to obtain carbon dioxide with a purity of 99%.

[0053] Example 4

[0054] Open the first valve, the fifth valve, the sixth valve, the seventh valve and the eighth valve, and close the second valve, the third valve and the fourth valve, and pass the medium-concentration CO2 (≥60%) mixed gas and high-volume gas (>50,000 cubic meters / day) gas into the pressure swing adsorption compressor, and then pass it through the secondary pressure swing adsorption unit, the membrane separation unit and the vacuum pump in sequence to obtain carbon dioxide with a purity of 99%.

[0055] Comparative Example 1

[0056] Under variable operating conditions, the carbon dioxide from the produced gas is captured, and the order of the purification device is adjusted so that the associated gas first passes through the membrane separation device, and then is connected to the first-stage pressure swing adsorption device, and then passes through the second-stage pressure swing adsorption device. During the test, we found that the pressure of the associated gas entering the membrane separation device is too low, and the membrane separation effect is poor. Finally, the separated and analyzed gas obtains the carbon dioxide content with a purity of 79%. In addition, due to the high price of the membrane in the membrane separation device, it is a waste of cost and cannot achieve the separation effect.

[0057] The above detailed description is a specific description of one feasible embodiment of the present invention. The embodiment is not intended to limit the patent scope of the present invention. Any equivalent implementation or modification that does not deviate from the present invention should be included in the scope of the technical solution of the present invention.

Claims

1. A variable operating condition produced gas carbon dioxide capture system, characterized in that: The capture system comprises an oilfield associated gas source outlet, a pressure swing adsorption compressor, a primary pressure swing adsorption unit, a secondary pressure swing adsorption unit, a membrane separation unit and a vacuum pump; wherein a first valve is arranged between the oilfield associated gas inlet and the pressure swing adsorption compressor; a second valve is arranged between the pressure swing adsorption compressor and the bottom of the primary pressure swing adsorption unit, a sixth valve and a seventh valve are arranged in sequence between the top of the secondary pressure swing adsorption unit and the membrane separation unit, a fourth valve is arranged between the pipeline between the top of the secondary pressure swing adsorption unit and the sixth valve and the top of the primary pressure swing adsorption unit, a third valve is arranged between the pipeline between the top of the primary pressure swing adsorption unit and the fourth valve and the bottom of the secondary pressure swing adsorption unit, a fifth valve is arranged between the pipeline between the pressure swing adsorption compressor and the second valve and the pipeline between the bottom of the secondary pressure swing adsorption unit and the third valve, and an eighth valve is arranged between the membrane separation unit and the vacuum pump.

2. The capture system according to claim 1, characterized in that: The associated gas source outlet of the oil field is a mixed gas containing 30%-60% CO2 and a gas volume of ≤50,000 cubic meters / day. The method of using the capture system is: first open the first valve, the second valve, the third valve, the sixth valve, the seventh valve, and the eighth valve, close the fourth valve and the fifth valve, and pass the mixed gas into the pressure swing adsorption compressor, and then pass through the first pressure swing adsorption unit and the second pressure swing adsorption unit in sequence, and then pass through the membrane separation unit, and after passing through the vacuum pump, obtain carbon dioxide with a purity of ≥95%.

3. The capture system according to claim 1, characterized in that: The associated gas source outlet of the oil field is a mixed gas containing ≥60% CO2 and a gas volume of ≤50,000 cubic meters / day. The method of using the capture system is: first open the first valve, the second valve, the fourth valve, the fifth valve, the sixth valve, the seventh valve, and the eighth valve, and close the third valve. The mixed gas first passes through the pressure swing adsorption compressor, and then is divided into a parallel primary pressure swing adsorption unit and a secondary pressure swing adsorption unit, and finally passes through a membrane separation unit and a vacuum pump to obtain carbon dioxide with a purity of ≥95%.

4. The capture system according to claim 1, characterized in that: The associated gas source outlet of the oil field is a mixed gas containing ≥60% CO2 and a gas volume of ≥50,000 cubic meters / day. The method of using the capture system is: first open the first valve, the fifth valve, the sixth valve, the seventh valve, and the eighth valve, and close the second valve, the third valve, and the fourth valve. The mixed gas is introduced into the pressure swing adsorption compressor, and then passes through the secondary pressure swing adsorption unit, the membrane separation unit and the vacuum pump in sequence to obtain carbon dioxide with a purity of ≥95%.

5. A process for capturing carbon dioxide from produced gas under variable operating conditions, characterized in that: The process method adopts the capture system according to any one of claims 1 to 4, and the method comprises the following steps: (1) subjecting the CO2-containing mixed gas to a first-stage pressure swing adsorption; (2) performing secondary pressure swing adsorption; (3) Perform membrane separation to obtain carbon dioxide gas with a purity of ≥95%.

6. The process according to claim 1, characterized in that: The membrane in step (3) is selected from 6FBI / ZIF-8 based carbon molecular sieve membrane doped with ZIF-8.

7. The process according to claim 5, characterized in that: The CO2 concentration in step (1) is 30-60% and the gas volume is ≤50,000 cubic meters per day. The process method adopts the capture system described in claim 2.

8. The process according to claim 5, characterized in that: In step (1), the concentration of CO2 in the mixed gas is ≥60% and the gas volume is ≤50,000 cubic meters / day, the primary pressure swing adsorption step is omitted, and the process method adopts the capture system described in claim 3.

9. The process according to claim 5, characterized in that: In step (1), the concentration of CO2 in the mixed gas is ≥60% and the gas volume is ≥50,000 cubic meters / day. The mixed gas is divided into two parts, one part is subjected to primary pressure swing adsorption to obtain gas A, and the other part is subjected to secondary pressure swing adsorption to obtain gas B. Gas A and gas B are separated by membrane together; the process method adopts the capture system described in claim 4.

10. Use of the capture system according to any one of claims 1 to 4 or the process according to any one of claims 5 to 9 in capturing carbon dioxide from associated gas with different CO2 concentrations and gas volumes.

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