Variable pressure absorption type carbon capture system based on compressed gas energy storage

Abstract

The invention belongs to the technical field of energy storage carbon capture, and particularly relates to a pressure swing absorption type carbon capture system based on compressed gas energy storage, the pressure swing absorption type carbon capture system comprises an energy storage unit, an energy release unit, a gas storage tank, a heat storage tank and a cold storage tank, the energy storage unit comprises a compressor set, a heat exchanger set, an ejector set, a gas-liquid separator set and a water turbine, and an amino solution is arranged in the ejector set; the amino solution is used for pressure swing absorption of CO2, the operation temperature is low, the risk of degradation of the amino solution can be effectively reduced, and the service life of equipment is prolonged; the ejector is used, so that the gas-liquid contact surface area can be increased, the sufficient mixing and absorption of the high-CO2-concentration gas and the amino solution are promoted, and the use of a huge absorption tower is avoided; according to the invention, an amino solution variable-pressure CO2 absorption method is combined with compressed gas energy storage, so that the device has the functions of electric peak regulation, safety guarantee and the like while capturing CO2, is suitable for industries such as electric power, chemical engineering, steel and the like, and has higher flexibility.

Description

Technical Field

[0001] The present invention relates to the technical field of energy storage carbon capture, and in particular to a pressure swing absorption carbon capture system based on compressed gas energy storage. Background Art

[0002] CO2 emission reduction is an important means to solve global warming. In order to effectively achieve the "dual carbon" goal, we must accelerate the low-carbonization of my country's energy structure. CO2 capture and storage technology can limit high CO2 concentration gas emissions in industries such as electricity, chemical and steel, and is an effective means to mitigate climate change. Post-combustion carbon capture technology based on amine-based solutions is easy to integrate with existing plants and is currently the most widely used carbon capture technology. However, this technology uses the principle of variable temperature absorption, that is, using amine-based solutions to absorb CO2 under low temperature conditions and desorb CO2 at high temperatures to obtain high-purity CO2 gas.

[0003] At present, the CO2 desorption process usually uses a large amount of low-pressure steam to provide heat. However, due to the poor thermal stability of amine-based solvents, thermal degradation problems are prone to occur during the desorption process. The thermal degradation of amines reduces the concentration of their solution, which will affect the subsequent CO2 absorption effect. The amine-based solvent needs to be continuously replenished, resulting in a large amount of solvent consumption. At the same time, the degradation products of amines are corrosive and will affect the service life of the equipment. Summary of the invention

[0004] The object of the present invention is to provide an environmentally friendly pressure swing absorption carbon capture system based on compressed gas energy storage, which can reduce the consumption of amine-based solvents, increase the life of capture equipment, and is environmentally friendly.

[0005] In order to achieve the above-mentioned object, the present invention adopts such a technical solution: a pressure swing absorption carbon capture system based on compressed gas energy storage, comprising an energy storage unit, an energy release unit, a gas storage tank, a heat storage tank and a cold storage tank; The energy storage unit comprises a compressor group, a heat exchanger group, an ejector group, a gas-liquid separator group and a turbine, wherein an amine-based solution is arranged in the ejector group; The compressor unit compresses the high-concentration CO2 gas to form a high-pressure high-CO2 concentration gas; The heat exchanger group is connected to the compressor group, and cools the high-pressure CO2 concentration gas to a temperature close to the ambient temperature to form a high-pressure, low-temperature CO2 concentration gas, and the compression heat is absorbed by the low-temperature heat transfer fluid in the cold storage tank, and the high-temperature heat transfer fluid after absorbing the compression heat is stored in the heat storage tank; The high-pressure, low-temperature, high-CO2 concentration gas enters the ejector group and is fully mixed with the pressurized amine-based solution, and the amine-based solution absorbs the high-CO2 concentration gas; The gas-liquid separator group is connected to the ejector group, and the unabsorbed low CO2 concentration gas is separated by the gas-liquid separator group and refluxed to the compressor group for re-pressurization, and finally the unabsorbed high-pressure low CO2 concentration gas is stored in the gas storage tank as an energy storage heat transfer fluid; The water turbine is connected to the gas-liquid separator group to expand and reduce the pressure of the amine-based solution that has reached CO2 absorption saturation, and obtain high-purity CO2 gas; The energy release unit includes an expansion unit, which is connected to the gas storage tank. After the low CO2 concentration gas in the gas storage tank absorbs the compression heat released by the heat storage tank, it enters the expansion unit to perform work and generate electricity.

[0006] Furthermore, the compression heat generated by the compressor group is stored in the heat storage tank, the compressor group includes at least two stages of compression of a first compressor and a second compressor, the heat exchanger group includes at least two stages of heat exchange of a first heat exchanger and a second heat exchanger, the number of the heat exchanger groups is consistent with the number of the compressor groups, and they are arranged one by one corresponding to the first compressor and the second compressor, the compression heat generated by the first compressor and the second compressor is absorbed by the low-temperature heat transfer fluid in the cold storage tank in the first heat exchanger and the second heat exchanger, and the high-temperature heat transfer fluid after heat absorption is stored in the heat storage tank.

[0007] Furthermore, the injector group includes at least two-stage injection subsystems of a first injector and a second injector, the gas-liquid separator group includes two-stage gas-liquid separation of a first gas-liquid separator and a second gas-liquid separator, the number of the gas-liquid separator groups is consistent with the number of the injector groups, and is arranged one by one corresponding to the first injector and the second injector, the CO2 concentration in the mixed gas in the second gas-liquid separator arranged at the rear is less than the CO2 concentration in the mixed gas in the first gas-liquid separator arranged at the front, and a booster pump is connected to the bottom of the second gas-liquid separator, and the amine-based solution containing no CO2 or a small amount of CO2 in the second gas-liquid separator is pressurized by a first booster pump to enter the first injector to continue absorbing CO2 gas.

[0008] Further, the working process of the energy storage unit is as follows: The flue gas generated after combustion in the thermal power plant, the high CO2 concentration gas after desulfurization, denitrification and dehydration treatment, enters the first compressor for compression to form high-pressure high-CO2 concentration gas. The compressed high-CO2 concentration gas is cooled to a temperature close to the ambient temperature through the first heat exchanger, and enters the first ejector to be fully mixed with the amine-based solution. The amine-based solution absorbs the high-CO2 concentration gas, and the unabsorbed gas is separated in the first gas-liquid separator and continues to enter the second ejector to repeat the absorption process. The remaining unabsorbed gas flows out from the top of the second gas-liquid separator, is further pressurized in the second compressor, and is cooled in the second heat exchanger. Finally, the unabsorbed high-pressure gas is stored in the gas storage tank as an energy storage heat transfer fluid.

[0009] Furthermore, it also includes a third heat exchanger and a second booster pump. During the process of pressure-switching absorption of CO2 by the amine-based solution, the amine-based solution containing no CO2 or a small amount of CO2 is pressurized by the second booster pump and then mixed with the gas with a lower CO2 concentration in the second ejector to absorb the CO2 gas therein; The amine-based solution that has absorbed part of the CO2 gas in the second gas-liquid separator is driven by the first booster pump and enters the first ejector to continue absorbing the CO2 gas to reach an absorption saturation state. The saturated CO2-rich amine-based solution is expanded and depressurized in the turbine and is moderately heated in the third heat exchanger by the excess compression heat in the heat storage tank.

[0010] Furthermore, it also includes a third gas-liquid separator and a fourth heat exchanger. The solution after the pressure reduction by the turbine is subjected to CO2 separation in the third gas-liquid separator. The amine-based solution containing no CO2 or a small amount of CO2 at the bottom of the third gas-liquid separator continues to be pressurized by the second booster pump or is cooled in the fourth heat exchanger and then pressurized to enter the second ejector to repeat the CO2 pressure swing absorption cycle, and high-purity CO2 gas is obtained at the top outlet of the third gas-liquid separator.

[0011] Further, the energy release unit further comprises an engine, a throttle valve, a fifth heat exchanger and a sixth heat exchanger, and the expansion unit comprises a two-stage expansion machine, namely a first expansion machine and a second expansion machine; The working process of the energy release unit is as follows: The high-pressure gas in the gas storage tank is throttled by the throttle valve, preheated in the fifth heat exchanger, expanded in the first expander, and then heated in the sixth heat exchanger. The low-pressure gas continues to expand in the second expander. The first expander and the second expander drive the generator to generate electricity.

[0012] Further, the heat in the fifth heat exchanger and the sixth heat exchanger comes from the heat storage tank.

[0013] By adopting the above-mentioned design scheme, the beneficial effects of the present invention are: 1. The present invention uses an amine-based solution to absorb CO2 by pressure swing, and the operating temperature is relatively low, which can effectively reduce the risk of degradation of the amine-based solution and increase the service life of the equipment; 2. The pressure swing absorption CO2 capture method based on compressed gas energy storage proposed in the present invention directly uses off-peak electricity as an energy source. By combining with compressed gas energy storage, it can reduce the carbon capture energy consumption of the amine-based solution pressure swing absorption method and improve energy utilization efficiency. 3. The present invention uses an ejector for CO2 absorption. The use of an ejector can increase the gas-liquid contact surface area, promote the full mixing and absorption of high CO2 concentration gas and amine-based solution, and avoid the use of a large absorption tower; 4. The present invention combines the method of absorbing CO2 by pressure swing of amine-based solution with compressed gas energy storage, which can capture CO2 while also having the functions of power peak regulation and safety assurance. It is suitable for industries such as power, chemical industry and steel, and has higher flexibility. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a structural schematic diagram of the present invention; In the figure: an air storage tank 1, a cold storage tank 21, a heat storage tank 22, a turbine 3, a first compressor 31, a second compressor 32, a first heat exchanger 41, a second heat exchanger 42, a third heat exchanger 43, a fourth heat exchanger 44, a fifth heat exchanger 45, a sixth heat exchanger 46, a first ejector 51, a second ejector 52, a first gas-liquid separator 61, a second gas-liquid separator 62, a third gas-liquid separator 63, a first boosting pump 71, a second boosting pump 72, a throttle valve 8, a first expander 91, and a second expander 92. DETAILED DESCRIPTION

[0015] The following is a clear and complete description of the technical solutions in the embodiments of the present invention in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0016] Reference Figure 1 : The pressure swing absorption carbon capture system based on compressed gas energy storage includes an energy storage unit, an energy release unit, a gas storage tank 1, a cold storage tank 21 and a heat storage tank 22. The energy storage unit includes a compressor group, a heat exchanger group, an ejector group, a gas-liquid separator group and a turbine 3.

[0017] The compressor unit compresses the high CO 2 concentration gas to form high-pressure high CO 2 concentration gas; the compression heat generated by the compressor unit is stored in the heat storage tank 22 .

[0018] Preferably, the compressor group includes at least two stages of compression of the first compressor 31 and the second compressor 32, the heat exchanger group includes at least two stages of heat exchange of the first heat exchanger 41 and the second heat exchanger 42, the number of the heat exchanger groups is consistent with the number of the compressor groups, and is arranged one by one corresponding to the first compressor 31 and the second compressor 32, and the compression heat generated by the first compressor 31 and the second compressor 32 is absorbed by the first heat exchanger 41 and the second heat exchanger 42 and then stored in the heat storage tank 22. Specifically, the cold source of the first heat exchanger 41 and the second heat exchanger 42 is provided by the cold storage tank 21, and the low-temperature heat transfer fluid of the cold storage tank 21 absorbs the compression heat generated by the first compressor 31 and the second compressor 32 in the first heat exchanger 41 and the second heat exchanger 42, and the high-temperature heat transfer fluid after absorbing the heat is stored in the heat storage tank 22.

[0019] Preferably, the injector group includes at least two-stage injection subsystems of a first injector 51 and a second injector 52, and amine-based solutions are provided in the first injector 51 and the second injector 52; high-pressure, low-temperature, high-CO2 concentration gas enters the first injector 51 and the second injector 52 to be fully mixed with the corresponding amine-based solution, and the amine-based solution absorbs the high-CO2 concentration gas.

[0020] The gas-liquid separator group is connected to the ejector group. The unabsorbed low CO2 concentration gas is separated by the gas-liquid separator group and returned to the compressor group for re-pressurization. Finally, the unabsorbed high-pressure low CO2 concentration gas is stored in the gas storage tank 1 as an energy storage heat transfer fluid.

[0021] Preferably, the gas-liquid separator group includes a first gas-liquid separator 61 and a second gas-liquid separator 62 for two-stage gas-liquid separation. The number of the gas-liquid separator groups is consistent with the number of the injector groups, and they are arranged one by one corresponding to the first injector 51 and the second injector 52. The CO2 concentration in the mixed gas in the second gas-liquid separator 62 arranged at the rear is less than the CO2 concentration in the mixed gas in the first separator arranged at the front. The bottom of the second gas-liquid separator is connected to a first booster pump 71, and the amine-based solution containing no CO2 or a small amount of CO2 in the second gas-liquid separator is pressurized by the first booster pump 71 to enter the first injector 51 to continue to absorb CO2 gas.

[0022] The turbine 3 is connected to the gas-liquid separator group to expand and reduce the pressure of the amine-based solution that has reached CO2 absorption saturation, and obtain high-purity CO2 gas.

[0023] Preferably, the present embodiment further comprises a third heat exchanger 43, a fourth heat exchanger 44, a third gas-liquid separator 63 and a second booster pump 72. During the pressure-swing absorption of CO2 by the amine-based solution, the amine-based solution containing no CO2 or a small amount of CO2 is pressurized by the second booster pump 72 and then mixed with the gas with a lower CO2 concentration in the second ejector 52 to absorb the CO2 gas therein; The amine solution that has absorbed part of the CO2 gas in the second gas-liquid separator 62 is driven by the first booster pump 71 and enters the first ejector 51 to continue absorbing the CO2 gas to reach an absorption saturation state. The saturated CO2-rich amine solution is expanded and depressurized in the turbine 3 and is moderately heated in the third heat exchanger 43 by the excess compression heat in the heat storage tank 22.

[0024] The solution after the pressure reduction by the turbine 3 is subjected to CO2 separation in the third gas-liquid separator 63, and the amine-based solution containing no CO2 or a small amount of CO2 at the bottom of the third gas-liquid separator 63 continues to be pressurized by the second booster pump 72 or is cooled in the fourth heat exchanger 44 and then pressurized to enter the second ejector 52 to repeat the CO2 pressure swing absorption cycle, and high-purity CO2 gas is obtained at the top outlet of the third gas-liquid separator 63.

[0025] The energy release unit includes an expansion unit, which is connected to the gas storage tank 1. After the low CO2 concentration gas in the gas storage tank 1 absorbs the compression heat released by the heat storage tank 22, it enters the expansion unit to perform work and generate electricity.

[0026] The workflow of the present invention is as follows: During the energy storage process, the high CO2 concentration gas after pretreatment (desulfurization, denitrification, and dehydration) is compressed to a higher pressure by the first compressor 31, which is driven by a motor and consumes off-peak electricity; The compressed high CO2 concentration gas is cooled to about ambient temperature through the first heat exchanger 41, and then enters the first ejector 51 to be fully mixed with the amine-based solution. The amine-based solution absorbs the CO2 gas, and the unabsorbed gas is separated in the first gas-liquid separator 61 and continues to enter the second ejector 52 to repeat the absorption process. The remaining unabsorbed gas flows out from the top of the second gas-liquid separator 62, is further pressurized in the second compressor 32, and is cooled in the second heat exchanger 42; The compression heat of the gas in the first heat exchanger 41 and the second heat exchanger 42 is absorbed by the low-temperature heat transfer fluid in the cold storage tank 21, and the high-temperature heat transfer fluid after absorbing heat is stored in the heat storage tank 22; Finally, the unabsorbed high-pressure gas is throttled by the throttle valve 8 and stored in the gas storage tank 1 as an energy storage heat transfer fluid.

[0027] During the process of pressure-switching absorption of CO2 by the amine-based solution, the amine-based solution containing no CO2 or a small amount of CO2 is pressurized by the second booster pump 72 and then mixed with the gas with a lower CO2 concentration in the second ejector 52 to absorb the CO2 gas therein. The use of an ejector can increase the gas-liquid contact surface ratio, promote the full mixing and absorption of CO2 and the amine-based solution in the gas, and avoid the use of a large absorption tower. Afterwards, the amine-based solution that has absorbed part of the CO2 gas is driven by the first booster pump 71 and enters the first ejector 51 to continue absorbing CO2 gas to reach the absorption saturation state. Therefore, the CO2 concentration in the mixed gas at the top outlet of the first gas-liquid separator 61 is higher than that at the outlet of the second gas-liquid separator 62. According to the difference in CO2 concentration in the gas at the outlets of the two separators, a multi-stage ejector subsystem can be adopted to increase the CO2 capture rate. The saturated CO2-rich amine-based solution expands and depressurizes in the turbine 3, and the turbine 3 can recover part of the electricity to reduce the energy consumption of CO2 capture. The depressurized solution can be directly separated from CO2 in the third gas-liquid separator 63, or can be moderately heated by the excess compression heat in the heat storage tank 21 to promote the CO2 desorption process. The amine-based solution containing no CO2 or a small amount of CO2 at the bottom of the third gas-liquid separator 63 continues to be pressurized by the second booster pump 72 or is cooled in the fourth heat exchanger 44 (heated by excess compression heat) and then pressurized into the second ejector 52 to repeat the CO2 pressure swing absorption cycle. High-purity CO2 gas is obtained at the top outlet of the third gas-liquid separator 63. The continuous ejector cycle CO2 absorption process can be carried out between the first compressor 31 and the second compressor 32, or after the second compressor 32. Carrying it out between the first compressor 31 and the second compressor 32 can reduce the gas compression energy consumption, and after the second compressor 32, the CO2 absorption-desorption pressure ratio can be increased to generate more excess compression heat.

[0028] The energy release process of the system is similar to that of a conventional compressed air energy storage system. The high-pressure gas in the gas storage tank 1 is released after being throttled by the throttle valve 8 to maintain a constant gas pressure. The throttled high-pressure gas is preheated in the fifth heat exchanger 45 and then expanded in the first expander 91. It is then heated in the sixth heat exchanger 46 and continues to expand in the second expander 92 to increase the output power. The two-stage expansion unit drives the generator to generate electricity to output electricity. The heat in the fifth heat exchanger 45 and the sixth heat exchanger 46 comes from the heat storage tank 22. After the heat in the heat storage tank 22 is used to heat the high-pressure gas, some heat is still left. This is because during the energy storage process, after the high CO2 concentration gas is compressed in the first compressor 31, part of the CO2 gas is captured, but the gas compression heat is absorbed by the heat transfer fluid and stored in the heat storage tank 22, so there is excess compression heat that can be used in the third heat exchanger 43 to heat the amine solution and promote CO2 desorption.

[0029] By adopting the above-mentioned design scheme, the beneficial effects of the present invention are: 1. The conventional amine-based solution CO2 absorption method adopts variable temperature absorption, i.e. low temperature absorption-high temperature desorption. The high temperature desorption process will produce thermal degradation, resulting in large solvent consumption, equipment corrosion and other problems. This patent uses amine-based solution to absorb CO2 with variable pressure, and the operating temperature is relatively low, which can effectively reduce the risk of amine-based solution degradation and increase the service life of the equipment. 2. Conventional amine-based solution temperature-swing absorption CO2 methods usually require a large amount of low-pressure steam to provide the heat required for solvent regeneration, which is very unfriendly to non-power production departments; the pressure-swing absorption CO2 capture method based on compressed gas energy storage proposed in this patent directly uses low-peak electricity as an energy source. By combining with compressed gas energy storage, it can reduce the carbon capture energy consumption of the amine-based solution pressure-swing absorption method and improve energy utilization efficiency; 3. Conventional amine-based solution temperature-variable CO2 absorption methods use an absorption tower to absorb CO2 gas. The amine-based solution and CO2 in the absorption tower cannot be fully mixed and absorbed, so the absorption tower needs to be equipped with multiple layers of trays, resulting in a large volume of the absorption tower. This patent uses an ejector to absorb CO2. The use of an ejector can increase the gas-liquid contact surface area, promote the full mixing and absorption of high CO2 concentration gas and amine-based solution, and avoid the use of a large absorption tower; 4. Conventional amine-based solution temperature-variable absorption of CO2 method can only achieve the purpose of carbon capture and has a single function. This patent combines the amine-based solution pressure-variable absorption of CO2 method with compressed gas energy storage, which can capture CO2 while also having functions such as power peak regulation and safety assurance. It is suitable for industries such as power, chemical and steel, and has higher flexibility.

[0030] The pressure swing absorption carbon capture system based on compressed gas energy storage of the present invention captures CO2 by means of pressure absorption-pressure reduction desorption assisted by a compressor, which can effectively reduce the thermal degradation problem of the amine-based solution and increase the service life of the equipment. At the same time, the unabsorbed gas can be used for energy storage, thereby improving energy utilization efficiency and reducing the energy consumption of the pressure swing absorption carbon capture method.

[0031] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A pressure swing absorption carbon capture system based on compressed gas energy storage, characterized in that: It includes energy storage unit, energy release unit, gas storage tank, heat storage tank and cold storage tank; The energy storage unit comprises a compressor group, a heat exchanger group, an ejector group, a gas-liquid separator group and a turbine, wherein an amine-based solution is arranged in the ejector group; The compressor unit compresses the high-concentration CO2 gas to form a high-pressure high-CO2 concentration gas; The heat exchanger group is connected to the compressor group, and cools the high-pressure CO2 concentration gas to a temperature close to the ambient temperature to form a high-pressure, low-temperature CO2 concentration gas, and the compression heat is absorbed by the low-temperature heat transfer fluid in the cold storage tank, and the high-temperature heat transfer fluid after absorbing the compression heat is stored in the heat storage tank; The high-pressure, low-temperature, high-CO2 concentration gas enters the ejector group and is fully mixed with the pressurized amine-based solution, and the amine-based solution absorbs the high-CO2 concentration gas; The gas-liquid separator group is connected to the ejector group, and the unabsorbed low CO2 concentration gas is separated by the gas-liquid separator group and refluxed to the compressor group for re-pressurization, and finally the unabsorbed high-pressure low CO2 concentration gas is stored in the gas storage tank as an energy storage heat transfer fluid; The water turbine is connected to the gas-liquid separator group to expand and reduce the pressure of the amine-based solution that has reached CO2 absorption saturation, and obtain high-purity CO2 gas; The energy release unit includes an expansion unit, which is connected to the gas storage tank. After the low CO2 concentration gas in the gas storage tank absorbs the compression heat released by the heat storage tank, it enters the expansion unit to perform work and generate electricity.

2. The pressure swing absorption carbon capture system based on compressed gas energy storage according to claim 1 is characterized in that: The compression heat generated by the compressor group is stored in the heat storage tank. The compressor group includes at least two stages of compression of a first compressor and a second compressor. The heat exchanger group includes at least two stages of heat exchange of a first heat exchanger and a second heat exchanger. The number of the heat exchanger groups is consistent with the number of the compressor groups, and they are arranged one by one corresponding to the first compressor and the second compressor. The compression heat generated by the first compressor and the second compressor is absorbed by the low-temperature heat transfer fluid in the cold storage tank in the first heat exchanger and the second heat exchanger, and the high-temperature heat transfer fluid after heat absorption is stored in the heat storage tank.

3. The pressure swing absorption carbon capture system based on compressed gas energy storage according to claim 2 is characterized in that: The injector group includes at least two-stage injection subsystems of a first injector and a second injector, and the gas-liquid separator group includes two-stage gas-liquid separation of a first gas-liquid separator and a second gas-liquid separator. The number of the gas-liquid separator groups is consistent with the number of the injector groups, and they are arranged one by one corresponding to the first injector and the second injector. The CO2 concentration in the mixed gas in the second gas-liquid separator arranged at the rear is less than the CO2 concentration in the mixed gas in the first gas-liquid separator arranged at the front. The bottom of the second gas-liquid separator is connected to a first booster pump, and the amine-based solution containing no CO2 or a small amount of CO2 in the second gas-liquid separator is pressurized by the first booster pump to enter the first injector to continue absorbing CO2 gas.

4. The pressure swing absorption carbon capture system based on compressed gas energy storage according to claim 3 is characterized in that: The working process of the energy storage unit is as follows: The flue gas generated after combustion in the thermal power plant, the high CO2 concentration gas after desulfurization, denitrification and dehydration treatment, enters the first compressor for compression to form high-pressure high-CO2 concentration gas. The compressed high-CO2 concentration gas is cooled to a temperature close to the ambient temperature through the first heat exchanger, and enters the first ejector to be fully mixed with the amine-based solution. The amine-based solution absorbs the high-CO2 concentration gas, and the unabsorbed gas is separated in the first gas-liquid separator and continues to enter the second ejector to repeat the absorption process. The remaining unabsorbed gas flows out from the top of the second gas-liquid separator, is further pressurized in the second compressor, and is cooled in the second heat exchanger. Finally, the unabsorbed high-pressure gas is stored in the gas storage tank as an energy storage heat transfer fluid.

5. The pressure swing absorption carbon capture system based on compressed gas energy storage according to claim 4 is characterized in that: It also includes a third heat exchanger and a second booster pump. During the process of amine-based solution absorbing CO2 by pressure swing, the amine-based solution containing no CO2 or containing a small amount of CO2 is pressurized by the second booster pump and then mixed with the gas with a lower CO2 concentration in the second ejector to absorb the CO2 gas therein; The amine-based solution that has absorbed part of the CO2 gas in the second gas-liquid separator is driven by the first booster pump and enters the first ejector to continue absorbing the CO2 gas to reach an absorption saturation state. The saturated CO2-rich amine-based solution is expanded and depressurized in the turbine and is moderately heated in the third heat exchanger by the excess compression heat in the heat storage tank.

6. The pressure swing absorption carbon capture system based on compressed gas energy storage according to claim 5 is characterized in that: It also includes a third gas-liquid separator and a fourth heat exchanger. The solution after depressurization by the turbine undergoes CO2 separation in the third gas-liquid separator. The amine-based solution containing no CO2 or a small amount of CO2 at the bottom of the third gas-liquid separator continues to be pressurized by the second booster pump or is cooled in the fourth heat exchanger and then pressurized to enter the second ejector to repeat the CO2 pressure swing absorption cycle. High-purity CO2 gas is obtained at the top outlet of the third gas-liquid separator.

7. The pressure swing absorption carbon capture system based on compressed gas energy storage according to claim 6 is characterized in that: The energy release unit further includes an engine, a throttle valve, a fifth heat exchanger and a sixth heat exchanger. The expansion unit includes a first expander and a second expander. The working process of the energy release unit is as follows: The high-pressure gas in the gas storage tank is throttled by the throttle valve, preheated in the fifth heat exchanger, expanded in the first expander, and then heated in the sixth heat exchanger. The low-pressure gas continues to expand in the second expander. The first expander and the second expander drive the generator to generate electricity.

8. The pressure swing absorption carbon capture system based on compressed gas energy storage according to claim 7 is characterized in that: The heat in the fifth heat exchanger and the sixth heat exchanger comes from the heat storage tank.

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