A pressure swing adsorption carbon dioxide capture and liquefaction system for thermal power units

Abstract

This invention provides a pressure swing adsorption (PSA) carbon dioxide capture and liquefaction system for thermal power units, relating to the field of thermal power generation technology. It includes a PSA unit and a liquefaction unit. The PSA unit comprises multiple absorption towers, a pressurization device, a vacuum device, and a pressure-stabilized storage tank. The pressurization device is connected to the bottom of each absorption tower via a flue gas shut-off valve. The bottom of each absorption tower is connected to the vacuum device and the pressure-stabilized storage tank. After pressurization, the raw flue gas enters the absorption towers for adsorption. After adsorption, the absorption towers undergo pressure equalization treatment, and then the vacuum device extracts the desorbed carbon dioxide into the pressure-stabilized storage tank. The liquefaction unit includes a compressor, a first heat exchanger, a second heat exchanger, a chiller, an expansion nozzle, a gas-liquid separator, and a storage tank. The carbon dioxide, after secondary cooling and refrigeration, enters the gas-liquid separator for separation, and the liquid carbon dioxide enters the storage tank. This system integrates the carbon dioxide PSA and liquefaction processes, improving the quality of captured carbon dioxide.

Description

Technical Field

[0001] This invention relates to the field of thermal power generation technology, and in particular to a pressure swing adsorption carbon dioxide capture and liquefaction system for thermal power units. Background Technology

[0002] With the increasing severity of global climate change, reducing greenhouse gas emissions has become an urgent global task, especially for carbon dioxide (CO2), one of the major greenhouse gases, whose emission control has received widespread attention. Coal, as one of the world's main energy sources, plays a crucial role in power generation; however, coal-fired power units generate substantial carbon emissions during power generation, causing serious environmental impacts. Therefore, developing efficient CO2 capture technologies to reduce CO2 emissions from coal-fired power units is of great significance for achieving carbon reduction targets and promoting energy structure transformation. Currently, various CO2 capture technologies exist, among which pressure swing adsorption (PSA), as a highly efficient gas separation technology, has received extensive research and application.

[0003] Pressure Swing Adsorption (PSA) technology is widely used for the separation and purification of industrial gases due to its unique working principle and advantages. This technology is based on the principle that different gases adsorb differently on the adsorbent surface under different pressures, and gas separation is achieved by changing the pressure. Compared with other CO2 capture technologies, PSA technology features low energy consumption, flexible operation, and strong adaptability. Especially when handling large flow rates and low concentrations of CO2 gas, PSA demonstrates high efficiency and economy. Furthermore, PSA equipment is compact and easy to scale up for industrial applications, making it ideal for CO2 capture in thermal power units.

[0004] In view of the above reasons, the present invention proposes a pressure swing adsorption carbon dioxide capture and liquefaction system for thermal power units to achieve CO2 capture in thermal power units. Summary of the Invention

[0005] The purpose of this invention is to provide a pressure swing adsorption (PSA) carbon dioxide capture and liquefaction system for thermal power units. This system can integrate the pressure swing adsorption and liquefaction processes of carbon dioxide to achieve cascaded energy utilization and improve the quality of captured carbon dioxide.

[0006] This invention provides a pressure swing adsorption (PSA) carbon dioxide capture and liquefaction system for thermal power units, comprising: a PSA unit and a liquefaction unit. The PSA unit includes multiple absorption towers, a pressurizing device, a vacuum device, and a pressure-stabilizing storage tank. The pressurizing device is connected to the bottom of each absorption tower via a flue gas shut-off valve. The bottom of each absorption tower is sequentially connected to the vacuum device and the pressure-stabilizing storage tank via pressure regulating valves. Flue gas from the thermal power unit is pressurized by the pressurizing device and enters the absorption tower. Carbon dioxide in the gas is adsorbed by the adsorption bed at the bottom of the absorption tower, while other gases are discharged from the top of the absorption tower. The absorption tower is then subjected to further treatment after adsorption. The pressure equalization process is performed, and then the vacuum device is turned on to extract the desorbed carbon dioxide and store it in the pressure-stabilized gas storage tank. The liquefaction unit includes a compressor, a first heat exchanger, a second heat exchanger, a refrigerator, an expansion nozzle, a gas-liquid separator, and a storage tank connected in sequence. The compressor is connected to the pressure-stabilized gas storage tank. The carbon dioxide stored in the pressure-stabilized gas storage tank is pressurized by the compressor and then enters the first heat exchanger and the second heat exchanger for secondary cooling. After cooling, it enters the refrigerator for refrigeration. The carbon dioxide cooled by the refrigerator is depressurized by the expansion nozzle and then enters the gas-liquid separator for separation. The resulting liquid carbon dioxide enters the storage tank.

[0007] Preferably, the number of absorption towers is at least four, with each pair of absorption towers forming a group, and at least two absorption towers in one group alternately operating in pressurized adsorption and vacuum desorption states, and at least two absorption towers in one group operating in a pressure equalization state.

[0008] Preferably, each of the absorption towers is equipped with a tail gas shut-off valve at its top, through which other gases not adsorbed by the adsorption bed are discharged.

[0009] Preferably, the inner sides of the tail gas shut-off valves at the top of each of the two absorption towers are connected by a pipe and a pressure balancing valve.

[0010] Preferably, each of the absorption towers is connected to the water inlet of the steam turbine condenser, and the inside of the absorption tower is heated by heat exchange with hot water taken from the water inlet of the steam turbine condenser, and the returned water after heat exchange is directed to the return water inlet of the steam turbine condenser.

[0011] Preferably, the power source of the compressor is the main steam of the steam turbine, and the steam after doing work is returned to the return water port of the steam turbine condenser.

[0012] Preferably, the liquid inlet of the first heat exchanger is connected to the water inlet of the condenser, and the liquid outlet of the first heat exchanger is connected to the water return outlet of the turbine condenser. The condensate from the water inlet of the turbine condenser is introduced into the first heat exchanger to exchange heat with carbon dioxide. After absorbing heat, the condensate returns to the water return outlet of the turbine condenser.

[0013] Preferably, the gas outlet of the gas-liquid separator is connected to the gas phase inlet of the second heat exchanger, and the gas phase outlet of the second heat exchanger is connected to the chimney. Carbon dioxide cooled by the first heat exchanger enters the second heat exchanger and exchanges heat with the low-temperature impurity gas separated by the gas-liquid separator before entering the refrigerator. The heated impurity gas is discharged into the chimney. Carbon dioxide cooled by the refrigerator enters the gas-liquid separator after being depressurized by the expansion nozzle. The liquid carbon dioxide generated after separation by the gas-liquid separator enters the storage tank for storage, and the impurity gas is returned to the second heat exchanger.

[0014] Preferably, the power source for both the pressurization device and the vacuum device is the main steam from the steam turbine, and the steam after doing work is returned to the return water port of the steam turbine condenser.

[0015] Preferably, the pressurizing device is a booster pump, and the vacuum device is a vacuum pump.

[0016] Compared with the prior art, the present invention has the following beneficial effects:

[0017] 1. The flue gas generated by thermal power units undergoes three processes in each absorption tower: pressurization adsorption, pressure equalization, and vacuum removal. Pressurization adsorption: Flue gas enters the absorption tower from the bottom. Carbon dioxide with a strong affinity for the adsorbent is selectively adsorbed into the adsorption bed, while other gases with a weak affinity are discharged from the top. The adsorption process ends before the carbon dioxide penetrates the adsorption bed. Pressure equalization: The absorption tower, after adsorption, is under high pressure and is connected to the absorption tower after vacuum removal to balance the pressure between the two towers. This process is mainly for recovering residual pressure energy. Vacuum removal: After pressure equalization, the absorption tower, filled with carbon dioxide, enters the regeneration stage. A vacuum pump is activated to evacuate the absorption tower, causing the CO2 adsorbed in the adsorption bed to be released from the adsorbent. The released carbon dioxide is stored in a pressure-stabilized gas storage tank for liquefaction. Through pressure swing adsorption and multiple absorption towers, continuous removal of carbon dioxide can be achieved, and residual pressure energy can be recovered and utilized, reducing the power consumption of the pressurization unit.

[0018] 2. The carbon dioxide stored in the pressure-stabilized gas storage tank can be cooled twice through the first and second heat exchangers. After cooling, it enters the refrigeration unit for cooling. The carbon dioxide cooled by the refrigeration unit enters the gas-liquid separator after being depressurized by the expansion nozzle. The resulting liquid carbon dioxide enters the storage tank for storage. The separated low-temperature impurity gas is passed to the second heat exchanger for heat exchange, which can reduce the amount of refrigerant extracted and used, realize the cascade utilization of energy, and improve the quality of carbon dioxide capture by combining pressure swing adsorption and liquefaction processes. Attached Figure Description

[0019] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 This is a schematic diagram of the working principle of the system of the present invention;

[0021] Explanation of reference numerals in the attached figures:

[0022] 1.1: First tail gas shut-off valve; 1.2: Second tail gas shut-off valve; 1.3: Third tail gas shut-off valve; 1.4: Fourth tail gas shut-off valve; 2.1: First pressure balancing valve; 2.2: Second pressure balancing valve; 3.1: First absorption tower; 3.2: Second absorption tower; 3.3: Third absorption tower; 3.4: Fourth absorption tower; 4.1: First flue gas shut-off valve; 4.2: Second flue gas shut-off valve; 4.3: Third flue gas shut-off valve; 4.4: Fourth flue gas shut-off valve; 5: Pressurization device; 6.1: First pressure regulating valve; 6.2: Second pressure regulating valve; 6.3: Third pressure regulating valve; 6.4: Fourth pressure regulating valve; 7: Vacuum device; 8: Pressure stabilizing gas storage tank; 9: Compressor; 10.1: First heat exchanger; 10.2: Second heat exchanger; 11: Refrigeration unit; 12: Expansion nozzle; 13: Gas-liquid separator; 14: Liquid storage tank;

[0023] P0: Raw flue gas; P1.1: Steam turbine condenser water inlet; P1.2: Steam turbine condenser water return outlet; P2: Steam turbine main steam; P3: Chimney. Detailed Implementation

[0024] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0025] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," and "counterclockwise," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limiting this invention.

[0026] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this invention, "a plurality of" means two or more, unless otherwise explicitly specified. Furthermore, the terms "installed," "connected," and "linked" should be interpreted broadly; for example, they may refer to a fixed connection, a detachable connection, or an integral connection; they may refer to a mechanical connection or an electrical connection; they may refer to a direct connection or an indirect connection through an intermediate medium; and they may refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0027] like Figure 1As shown, this invention discloses a pressure swing adsorption (PSA) carbon dioxide capture and liquefaction system for thermal power units, comprising: a PSA unit and a liquefaction unit. The PSA unit includes multiple absorption towers, a pressurizing device 5, a vacuum device 7, and a pressure-stabilizing storage tank 8. The pressurizing device 5 is connected to the bottom of each absorption tower via a flue gas shut-off valve. The bottom of each absorption tower is sequentially connected to the vacuum device 7 and the pressure-stabilizing storage tank 8 via pressure regulating valves. The raw flue gas P0 from the thermal power unit is pressurized by the pressurizing device 5 and enters the absorption tower. The carbon dioxide in the flue gas is adsorbed by the adsorption bed at the bottom of the absorption tower, while other gases are discharged from the top of the absorption tower. After adsorption, the pressure inside the absorption tower is equalized to reduce the pressure. Then, the vacuum device 7 is activated to extract the gases desorbed from the adsorption beds in each absorption tower. The carbon dioxide enters the pressure-stabilized gas storage tank 8 for storage; the liquefaction unit includes a compressor 9, a first heat exchanger 10.1, a second heat exchanger 10.2, a refrigerator 11, an expansion nozzle 12, a gas-liquid separator 13, and a storage tank 14 connected in sequence. The compressor 9 is connected to the pressure-stabilized gas storage tank 8. The carbon dioxide stored in the pressure-stabilized gas storage tank 8 is pressurized by the compressor 9 and then enters the first heat exchanger 10.1 and the second heat exchanger 10.2 for secondary cooling. After cooling, it enters the refrigerator 11 for refrigeration. The carbon dioxide cooled by the refrigerator 11 is depressurized by the expansion nozzle 12 and then enters the gas-liquid separator 13 for separation. The liquid carbon dioxide generated after separation enters the storage tank 14, and the separated low-temperature impurity gas is passed to the second heat exchanger 10.2 for heat exchange.

[0028] The pressure swing adsorption (PSA) unit contains at least four absorption towers. In this embodiment, there are four absorption towers, arranged in pairs: a first absorption tower 3.1, a second absorption tower 3.2, a third absorption tower 3.3, and a fourth absorption tower 3.4. The pressurization device 5 is connected to the bottoms of the first absorption tower 3.1, the second absorption tower 3.2, the third absorption tower 3.3, and the fourth absorption tower 3.4 via a first flue gas shut-off valve 4.1, a second flue gas shut-off valve 4.2, a third flue gas shut-off valve 4.3, and a fourth flue gas shut-off valve 4.4, respectively. The flow of raw flue gas into each absorption tower can be controlled via these flue gas shut-off valves. The bottoms of the first absorption tower 3.1, the second absorption tower 3.2, the third absorption tower 3.3, and the fourth absorption tower 3.4 are respectively connected to the vacuum device 7 through the first pressure regulating valve 6.1, the second pressure regulating valve 6.2, the third pressure regulating valve 6.3, and the fourth pressure regulating valve 6.4. The vacuum suction pressure of the vacuum device 7 can be controlled by each pressure regulating valve. At least two absorption towers in at least one group connected to the vacuum device 7 are alternately in the state of pressurized adsorption and vacuum desorption, and at least two absorption towers in at least one group are in the state of equal pressure, thereby realizing the continuous removal of carbon dioxide.

[0029] In this embodiment, the tops of the first absorption tower 3.1, the second absorption tower 3.2, the third absorption tower 3.3, and the fourth absorption tower 3.4 are respectively connected to a first tail gas shut-off valve 1.1, a second tail gas shut-off valve 1.2, a third tail gas shut-off valve 1.3, and a fourth tail gas shut-off valve 1.4. Other gases not adsorbed by the adsorption bed are discharged through each tail gas shut-off valve. The side of the first tail gas shut-off valve 1.1 and the second tail gas shut-off valve 1.2 closest to the first absorption tower 3.1 or the second absorption tower 3.2 is connected to a first pressure balancing valve 2.1 via a pipe. The side of the third tail gas shut-off valve 1.3 and the fourth tail gas shut-off valve 1.4 closest to the third absorption tower 3.3 or the fourth absorption tower 3.4 is connected to a second pressure balancing valve 2.2 via a pipe. The pressure balancing valves can balance the internal pressure of an absorption tower after adsorption is completed, thus reducing its internal pressure.

[0030] All four absorption towers involve three processes: pressurized adsorption, pressure equalization, and vacuum removal. Each adsorption stage is a combination of these three processes.

[0031] Pressurized adsorption: The raw flue gas enters the absorption tower from the bottom. Carbon dioxide, which has a strong affinity for the adsorbent, is selectively adsorbed in the adsorption bed in the flue gas entering the absorption tower, while other gases with a weak affinity for the adsorbent are discharged from the top of the tower through the tail gas shut-off valves. The adsorption process ends before carbon dioxide penetrates the adsorption bed.

[0032] Pressure equalization process: The absorption tower that has completed adsorption is under high pressure and will be connected to the absorption tower that has completed vacuum removal. That is, if the first absorption tower 3.1 has completed adsorption and is under high pressure, the first pressure balancing valve 2.1 will be opened to connect the second absorption tower 3.2 that has completed vacuum removal to it, so as to balance the pressure between the two towers. This process is mainly to realize the recovery of residual pressure energy.

[0033] Vacuum removal: After the equalization process is completed, the absorption tower, which is full of carbon dioxide, enters the regeneration stage. The vacuum device 7 is turned on to perform a vacuum operation on the absorption tower, which causes the CO2 adsorbed in the bed to be desorbed from the adsorbent. The desorbed carbon dioxide enters the pressure-stabilized gas storage tank 8 for storage.

[0034] The specific process for achieving continuous removal is as follows: By installing pressure balancing valves between each group of absorption towers, it is necessary to ensure that two absorption towers in one group are in the pressurized adsorption and vacuum desorption processes respectively, while two absorption towers in another group are in the pressure equalization process. The sequence of adsorption, desorption, and pressure equalization processes in the several adsorption tanks is as follows: When the first absorption tower 3.1 adsorbs, the second absorption tower 3.2 desorbs, and the third absorption tower 3.3 and the fourth absorption tower 3.4 equalize pressure. At the same time that the first absorption tower 3.1 completes adsorption, the second absorption tower 3.2 completes desorption, and the third absorption tower 3.3 and the fourth absorption tower 3.4 complete pressure equalization; subsequently, the fourth absorption tower 3.4 begins adsorption, the third absorption tower 3.3 desorbs, the first absorption tower 3.1 and the second absorption tower 3.2 enter the pressure equalization process, and simultaneously, the fourth absorption tower 3.4... 4. Upon completion of adsorption, the third absorption tower 3.3 completes desorption, and the first absorption tower 3.1 and the second absorption tower 3.2 achieve pressure equalization. Subsequently, the second absorption tower 3.2 begins adsorption, the first absorption tower 3.1 begins desorption, and the third absorption tower 3.3 and the fourth absorption tower 3.4 perform pressure equalization. When the second absorption tower 3.2 completes adsorption, the first absorption tower 3.1 completes desorption, and the third absorption tower 3.3 and the fourth absorption tower 3.4 achieve pressure equalization. This completes one full adsorption cycle.

[0035] Taking the first absorption tower 3.1 in the pressurized adsorption process, the second absorption tower 3.2 in the vacuum desorption process, and the third absorption tower 3.3 and the fourth absorption tower 3.4 in the pressure equalization process as an example, the operation process of the entire transformer system is described as follows:

[0036] The first flue gas shut-off valve 4.1 is in the open state, while the second, third, and fourth flue gas shut-off valves 4.2, 4.3, and 4.4 are in the closed state. The raw flue gas P0 from the thermal power unit is pressurized by the pressurization device 5 and enters the first absorption tower 3.1 from the bottom through the first flue gas shut-off valve 4.1. After being adsorbed by the adsorbent in the first absorption tower 3.1, carbon dioxide with a strong affinity for the adsorbent is selectively adsorbed in the bed, while other gases with a weak affinity for the adsorbent are discharged from the top of the first absorption tower 3.1 through the first tail gas shut-off valve 1.1 into the chimney P3. It should be noted that at this time, the first tail gas shut-off valve 1.1 is in the open state, the second, third, and fourth tail gas shut-off valves 1.2, 1.3, and 1.4 are in the closed state, the first pressure balancing valve 2.1 is in the closed state, and the second pressure balancing valve 2.2 is in the open state.

[0037] While the first absorption tower 3.1 is adsorbing, the carbon dioxide saturated in the second absorption tower 3.2 passes through the second pressure regulating valve 6.2 from the bottom of the tower, and then through the vacuum device 7 into the pressure-stabilized gas storage tank 8. It should be noted that at this time, the third pressure regulating valve 6.3, the fourth pressure regulating valve 6.4, and the first pressure regulating valve 6.1 are in the closed state, while the second pressure regulating valve 6.2 is in the open state.

[0038] Meanwhile, the third absorption tower 3.3, which has completed the carbon dioxide adsorption process, and the fourth absorption tower 3.4, which has completed the adsorption and desorption process, undergo a pressure equalization process. The impurity gas with higher pressure in the third absorption tower 3.3 enters the fourth absorption tower 3.4 through the second pressure balancing valve 2.2 until pressure balance is achieved.

[0039] In this embodiment, the absorption towers in the system require constant temperature during the adsorption process. Each absorption tower is connected to the water inlet P1.1 of the steam turbine condenser. Hot water taken from the steam turbine condenser water inlet is used to exchange heat and raise the temperature inside the absorption tower to stabilize the temperature inside the absorption tower. Since the system heats and cools simultaneously, the return water temperature is the same as the intake water temperature. Therefore, the water after heat exchange enters the steam turbine condenser return water inlet P1.2. The driving source of the vacuum device 7 and the compressor 9 in the system comes from the main steam P2 of the thermal power unit steam turbine. The steam after doing work also returns to the steam turbine condenser return water inlet P1.2.

[0040] In this embodiment, the liquid phase inlet of the first heat exchanger 10.1 is connected to the condenser water inlet P1.1, and the liquid phase outlet of the first heat exchanger 10.1 is connected to the turbine condenser return water inlet P1.2. Condensate from the turbine condenser water inlet P1.1 enters the first heat exchanger 10.1 to exchange heat with carbon dioxide. After absorbing heat, the condensate returns to the turbine condenser return water inlet P1.2. By using condenser condensate as a cold source, constant temperature control of the system is achieved, and the system's heat is used to heat the condensate, realizing the cascade utilization of energy.

[0041] The gas outlet of the gas-liquid separator 13 is connected to the gas phase inlet of the second heat exchanger 10.2. The gas phase outlet of the second heat exchanger 10.2 is connected to the chimney P3. The carbon dioxide cooled by the first heat exchanger 10.1 enters the second heat exchanger 10.2 and exchanges heat with the low-temperature impurity gas separated by the gas-liquid separator 13. After cooling, the impurity gas enters the refrigerator 11. The heated impurity gas is discharged into the chimney P3. The carbon dioxide cooled by the refrigerator 11 enters the gas-liquid separator 13 after being depressurized by the expansion nozzle 12. The liquid carbon dioxide generated after separation by the gas-liquid separator 13 enters the storage tank 14 for storage. The impurity gas returns to the second heat exchanger 10.2 for heat exchange, thereby realizing the cascade recovery and utilization of energy.

[0042] In this embodiment, the booster device 5 is a booster pump, and the vacuum device 7 is a vacuum pump. Both are powered by the main steam P2 of the steam turbine. The steam after performing work returns to the steam turbine condenser return port P1.2. Using the main steam P2 of the thermal power unit's steam turbine as the power source for the compression and vacuum equipment reduces the system's electricity consumption and improves the system's economy.

[0043] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A pressure swing adsorption carbon dioxide capture and liquefaction system for thermal power units, characterized in that, include: The system comprises a pressure swing adsorption (PSA) unit and a liquefaction unit. The PSA unit includes multiple absorption towers, a pressurizing device, a vacuum device, and a pressure-stabilized storage tank. The pressurizing device is connected to the bottom of each absorption tower via a flue gas shut-off valve. The bottom of each absorption tower is connected to the vacuum device and the pressure-stabilized storage tank sequentially via pressure regulating valves. Flue gas from the thermal power unit is pressurized by the pressurizing device and enters the absorption tower. Carbon dioxide is adsorbed by the adsorption bed at the bottom of the absorption tower, while other gases are discharged from the top. After adsorption, the absorption tower undergoes pressure equalization treatment, and then the vacuum device is activated to extract the desorbed carbon dioxide and store it in the pressure-stabilized storage tank. The liquefaction unit includes a compressor, a first heat exchanger, a second heat exchanger, a refrigerator, an expansion nozzle, a gas-liquid separator, and a storage tank, connected sequentially. The compressor is connected to the pressure-stabilized storage tank. Carbon dioxide stored in the pressure-stabilized storage tank is pressurized by the compressor and then sequentially enters the first heat exchanger and the liquefaction tank. The second heat exchanger performs secondary cooling, and the cooled water then enters the refrigeration unit for cooling. The liquid inlet of the first heat exchanger is connected to the water inlet of the turbine condenser, and the liquid outlet of the first heat exchanger is connected to the water return outlet of the turbine condenser. Condensate from the water inlet of the turbine condenser enters the first heat exchanger to exchange heat with carbon dioxide. After absorbing heat, the condensate returns to the water return outlet of the turbine condenser. The gas outlet of the gas-liquid separator is connected to the gas inlet of the second heat exchanger, and the gas outlet of the second heat exchanger is connected to the chimney. Carbon dioxide cooled by the first heat exchanger enters the second heat exchanger and exchanges heat with the low-temperature impurity gas separated by the gas-liquid separator. After cooling, the carbon dioxide enters the refrigeration unit, and the heated impurity gas is discharged into the chimney. Carbon dioxide cooled by the refrigeration unit enters the gas-liquid separator after being depressurized by the expansion nozzle. The liquid carbon dioxide generated after separation by the gas-liquid separator enters the storage tank for storage, and the impurity gas returns to the second heat exchanger.

2. The pressure swing adsorption carbon dioxide capture and liquefaction system for thermal power units according to claim 1, characterized in that, The number of absorption towers is at least four, with each pair of absorption towers forming a group. In at least one group, two absorption towers alternate between pressurized adsorption and vacuum desorption states, and in at least one group, two absorption towers are in a pressure equalization state.

3. The pressure swing adsorption carbon dioxide capture and liquefaction system for thermal power units according to claim 2, characterized in that, Each of the absorption towers is equipped with a tail gas shut-off valve at the top, through which other gases not adsorbed by the adsorption bed are discharged.

4. The pressure swing adsorption carbon dioxide capture and liquefaction system for thermal power units according to claim 3, characterized in that, The inner sides of the tail gas shut-off valves at the top of each of the two absorption towers are connected by pipes and pressure balancing valves.

5. The pressure swing adsorption carbon dioxide capture and liquefaction system for thermal power units according to claim 1, characterized in that, Each of the absorption towers is connected to the water inlet of the steam turbine condenser. The hot water taken from the water inlet of the steam turbine condenser is used to exchange heat and raise the temperature inside the absorption tower. The returned water after heat exchange is directed to the return water inlet of the steam turbine condenser.

6. The pressure swing adsorption carbon dioxide capture and liquefaction system for thermal power units according to claim 1, characterized in that, The compressor is powered by the main steam from the turbine, and the steam after it has done work is returned to the return water inlet of the turbine condenser.

7. The pressure swing adsorption carbon dioxide capture and liquefaction system for thermal power units according to claim 1, characterized in that, The power source for both the booster device and the vacuum device is the main steam from the steam turbine. The steam that has done work is returned to the return water inlet of the steam turbine condenser.

8. The pressure swing adsorption carbon dioxide capture and liquefaction system for thermal power units according to claim 7, characterized in that, The booster device is a booster pump, and the vacuum device is a vacuum pump.

Images