A power plant carbon capture system coupled with a refrigeration cycle to provide cooling

Abstract

The present application belongs to the technical field of carbon capture and energy saving of coal-fired power plants, and particularly relates to a power plant carbon capture system coupled with a refrigeration cycle to realize cold supply. The system is connected to a heat exchanger at the evaporation end of a cold supply system through a condenser of a power plant steam-water system, the heat exchanger at the evaporation end of the cold supply system is connected to a chilled water supply system, after circulating through the chilled water system, the system is connected to a heat carrier inlet of a carbonation reactor from a chilled water return system, a heat carrier outlet of the carbonation reactor is connected to a heat carrier inlet of a regenerated adsorbent cooling bed, a heat carrier outlet of the regenerated adsorbent cooling bed is connected to a regenerated mixed gas cooler, and the regenerated mixed gas cooler is connected to a low-pressure heater of the power plant steam-water system. The present application effectively recycles the low-temperature waste heat released by the carbon capture system, can greatly reduce the energy consumption and operation cost of the compression stage of the carbon capture system, and widens the utilization way of carbon dioxide.

Description

Technical Field

[0001] The present invention relates to the technical field of carbon capture and energy conservation in coal-fired power plants, and more particularly to a power plant carbon capture system coupled with a refrigeration cycle to achieve cooling. Background Art

[0002] To reduce CO2 emissions and mitigate the greenhouse effect, carbon capture and storage technologies will continue to play a key role. Among them, the use of highly active alkali metal-based solid adsorbents to adsorb CO2 can capture carbon dioxide at lower temperatures without the equipment corrosion problems associated with wet capture technology. Furthermore, the adsorbent is not easily deactivated and there is no secondary pollution, so it has good application prospects. The process of capturing CO2 with alkali metal-based solid adsorbents mainly involves the following two reactions:

[0003] Adsorption reaction: M2CO3(s)+CO2(g)+H2O(g)→2MHCO3(s)

[0004] Desorption reaction: 2MHCO3(s)→M2CO3(s)+CO2(g)+H2O(g)(M=K, Na)

[0005] Existing integrated, coupled heat recovery schemes for carbon capture and storage systems in coal-fired power plants are as follows: Steam extracted from the power plant's steam turbine provides the regeneration reaction heat. To prevent damage to the final blades caused by low steam flow in the low-pressure turbine, the cooling heat of the regenerated gas, the cooling heat of the regenerated adsorbent, and the heat released by the adsorption reaction are recovered to heat the power plant's condensate, replacing part of the feedwater low-pressure heat exchanger. This heat recovery scheme effectively recovers low-grade waste heat from the alkali metal-based solid adsorbent carbon capture process, significantly alleviating the problem of excessive energy consumption limiting the industrial application of carbon capture systems.

[0006] However, the cost of existing CO2 capture, transportation, and storage (CCUS) technologies remains high. Compression and storage account for significant energy consumption throughout the entire CCUS carbon lifecycle, but research that comprehensively considers reducing the cost and energy consumption of CCUS technologies is currently lacking. The energy-intensive pressurization process can result in a 3-4% loss in energy efficiency at power plants. Furthermore, due to geological constraints, not all EOR projects can be the final destination for CO2, making it imperative to expand the pathways for CO2 storage and utilization. Summary of the Invention

[0007] The purpose of the present invention is to provide a power plant carbon capture system that is coupled with a refrigeration cycle to achieve cooling, so as to solve the problem of low energy consumption and high energy consumption of the existing carbon dioxide pressurized liquefaction process, and at the same time solve the problem that the captured carbon dioxide cannot be stored in CO2 sites with suitable geological conditions and feasible costs.

[0008] A power plant carbon capture system coupled with a refrigeration cycle to achieve cooling, comprising a power generation system of a coal-fired unit, an alkali metal-based dry carbon dioxide capture system, a carbon dioxide post-processing system, a carbon dioxide refrigeration compression cycle system, and a chilled water circulation system;

[0009] The power generation system of the coal-fired unit includes the boiler, flue gas treatment device, steam turbine, generator, feedwater pump turbine, condenser, condensate pump, low-pressure heater, deaerator, feedwater pump, high-pressure heater and their connecting pipes and valves;

[0010] The alkali metal-based dry carbon dioxide capture system includes a booster fan, a carbonation reactor, a cyclone separator, a regeneration reactor, a regenerated adsorbent cooling bed, a regenerated mixed gas cooler, a circulating fan and its connecting pipes and valves;

[0011] The carbon dioxide post-processing system includes a first heat exchanger, a cooling water pump, a cooling tower, a second heat exchanger, a compressor, an air-cooled condenser, a throttle valve, a third heat exchanger and connecting pipes and valves thereof;

[0012] The carbon dioxide refrigeration cycle system includes an evaporator, a carbon dioxide-specific compressor, a high-temperature heat exchanger, a gas cooler, an expander, and connecting pipes and valves;

[0013] The chilled water circulation system includes a water distributor, a fan coil unit, a water collector, a dirt remover, a chilled water pump and its connecting pipes and valves;

[0014] A portion of the condensate at the condenser outlet is cooled by the refrigeration cycle evaporator, mixed with the cold water at the chiller evaporator outlet and sent to the fan coil unit. After heat exchange with the treated air, it passes through the water collector and the decontamination device for convergence and purification. The main stream of chilled water returns to the chiller, and its branch flows into the heat carrier pipeline of the carbonation reactor, taking away the heat released by the adsorption reaction to maintain the reaction temperature. The cooling heat released by the high-temperature solid adsorbent in the regenerated adsorbent cooling bed is then used to complete the second heating. Finally, the third heating is achieved by heat exchange with the regenerated mixed gas.

[0015] The boiler flue gas outlet is connected to the flue gas treatment device inlet and the steam turbine high-pressure cylinder. The steam turbine intermediate-pressure cylinder outlet is connected to the feedwater pump turbine. The steam turbine low-pressure cylinder is connected to the generator through a flange. The steam turbine low-pressure cylinder exhaust steam outlet and the feedwater pump turbine exhaust steam outlet are connected to the condenser. The condenser is connected to the low-pressure heater through the condensate pump. The low-pressure heater is connected to the deaerator. The deaerator is connected to the high-pressure heater through the feedwater pump. The high-pressure heater is then connected to the boiler feedwater inlet.

[0016] The feedwater pump turbine utilizes steam extracted from the intermediate pressure cylinder of the main steam turbine as its working fluid. The exhaust steam mixes with the main steam and enters the condenser, where the generated power is directly used to drive the feedwater pump. The flue gas treatment device is connected to the carbonation reactor via a booster fan, which in turn is connected to a cyclone separator, which is in turn connected to a regeneration reactor. One end of the regeneration reactor's product outlet is connected to a circulating fan via a cyclone separator, and the other end is connected to a regenerated adsorbent cooling bed.

[0017] In the dry carbon dioxide capture system, the flue gas after desulfurization, denitrification and dust removal is pressurized by a booster fan and then enters the carbonation reactor to react with a highly active sodium-based solid adsorbent to remove CO2 from the flue gas; the adsorbent after the reaction is separated by a cyclone separator, and a part of the mixed gas is discharged and then enters the regeneration reactor through a circulating fan for recycling. The high-temperature adsorbent after regeneration is heated by the steam extraction from the steam turbine and cooled by the condensate return water and then returned to the carbonation reactor. A large part of the regenerated mixed gas at the outlet of the regeneration reactor is used as the fluidizing medium, and the remaining part of the regenerated mixed gas enters the cooler to heat the extracted condensate return water.

[0018] The first heat exchanger is connected to the second heat exchanger, the second heat exchanger is connected to the compressor, and the compressor is connected to the third heat exchanger to form a mainstream flow of carbon dioxide;

[0019] The circulating cooling water that provides cooling capacity for the first stage of cooling passes through the first heat exchanger, cooling water pump and cooling tower in sequence to form a circulation. The refrigerant R717 that provides cooling capacity for the third stage of cooling passes through the third heat exchanger, compressor, air-cooled condenser and throttle valve in sequence to form a refrigeration cycle. The refrigerant cycle that provides cooling capacity for the second stage of cooling is similar to the above refrigeration cycle.

[0020] The carbon dioxide gas in the carbon dioxide post-treatment system, which has been pre-treated by the regenerative mixed gas cooler, enters the first heat exchanger and uses the circulating cooling water supplied by the cooling tower to achieve the first stage of cooling. It then enters the second heat exchanger and uses the compression refrigeration cycle of the refrigerant R717 to achieve the second stage of cooling. The carbon dioxide gas after the primary cooling enters the compressor for pressurization, and finally completes the final cooling through heat absorption at the evaporation end of the refrigerant R717 refrigeration cycle.

[0021] The exhaust port of the carbon dioxide dedicated compressor is connected to the high-temperature heat exchanger, the high-temperature heat exchanger is connected to the gas cooler, the gas cooler is connected to the expander, the exhaust port of the expander is connected to the evaporator, and the evaporator is connected to the air inlet of the carbon dioxide dedicated compressor to form a cycle;

[0022] In the carbon dioxide compression refrigeration cycle, the carbon dioxide gas that has undergone secondary treatment is injected into the compressor. After being compressed into a high-temperature, high-pressure supercritical state by the compressor, the carbon dioxide gas enters the high-temperature heat exchanger to be cooled by circulating hot water, and then enters the gas cooler to be further cooled by cooling water. The high-pressure carbon dioxide gas at the outlet of the gas cooler is cooled and depressurized by the expander, and then enters the evaporator to absorb a large amount of heat from the extracted condensate and vaporize into superheated steam. The steam enters the compressor to increase the pressure, and the cycle is repeated over and over again.

[0023] The chilled water supply port of the chiller is connected to the water distributor, the water distributor is connected to the fan coil unit, the fan coil unit is connected to the water collector, the water collector is connected to the sludge remover, the sludge remover is connected to the chilled water pump, and the chilled water pump is connected to the chilled water return port of the chiller.

[0024] Compared with the prior art, the present invention has the following significant advantages:

[0025] 1. Compared with existing power plant-coupled carbon capture systems, which utilize condensate at the condenser outlet to recover waste heat released during the carbon capture process, the present invention utilizes a portion of the condensate at the condenser outlet as a heat source at the evaporation end of the carbon dioxide compression refrigeration system. This realizes the refrigeration cycle while lowering the temperature of the condensate entering the heat carrier pipeline of the carbonation reactor. This increases the heat recovery temperature difference of the waste heat released by the adsorption reaction, thereby reducing the amount of heating surface layout, shrinking the reactor size, and effectively reducing equipment costs.

[0026] 2. The present invention processes carbon dioxide gas to the pressure and temperature state required by the refrigeration cycle, and applies carbon dioxide as a refrigerant to the refrigeration cycle, providing chilled water for the chilled water circulation system while heating the hot network water to the heating temperature, greatly reducing the operating cost of CO2 pressurized liquefaction treatment, to a certain extent reducing the power consumption required by the carbon capture system to capture unit mass of CO2, and creating economic value for cooling, broadening the ways to utilize CO2. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 It is a schematic diagram of the overall system of the present invention;

[0028] List of reference numerals: 1 is a boiler, 2 is a steam turbine, 3 is a generator, 4 is a feedwater pump turbine, 5 is a condenser, 6 is a condensate pump, 7 is a low-pressure heater, 8 is a deaerator, 9 is a feedwater pump, 10 is a high-pressure heater, 11 is a flue gas processor, 12 is a booster fan, 13 is a carbonation reactor, 14 is a cyclone separator, 15 is a regeneration reactor, 16 is a circulating fan, 17 is a regenerated adsorbent cooling bed, 18 is a regenerated mixed gas cooler, 19 is a regenerated adsorbent cooling bed, It is the first heat exchanger, 20 is the cooling water pump, 21 is the cooling tower, 22 is the second heat exchanger, 23 is the compressor, 24 is the third heat exchanger, 25 is the throttle valve, 26 is the air-cooled condenser, 27 is the carbon dioxide dedicated compressor, 28 is the high-temperature heat exchanger, 29 is the gas cooler, 30 is the expander, 31 is the evaporator, 32 is the water distributor, 33 is the fan coil unit, 34 is the water collector, 35 is the decontamination device, 36 is the chilled water pump, and 37 is the chiller. DETAILED DESCRIPTION

[0029] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of 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 described embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field are within the scope of protection of the present invention.

[0030] Figure 1 Schematic diagram of the overall system of the present invention, list of reference numerals: 1 is a boiler, 2 is a steam turbine, 3 is a generator, 4 is a feedwater pump turbine, 5 is a condenser, 6 is a condensate pump, 7 is a low-pressure heater, 8 is a deaerator, 9 is a feedwater pump, 10 is a high-pressure heater, 11 is a flue gas processor, 12 is a booster fan, 13 is a carbonation reactor, 14 is a cyclone separator, 15 is a regeneration reactor, 16 is a circulating fan, 17 is a regenerated adsorbent cooling bed, 18 is a regenerated mixed gas Body cooler, 19 is the first heat exchanger, 20 is the cooling water pump, 21 is the cooling tower, 22 is the second heat exchanger, 23 is the compressor, 24 is the third heat exchanger, 25 is the throttle valve, 26 is the air-cooled condenser, 27 is the carbon dioxide dedicated compressor, 28 is the high-temperature heat exchanger, 29 is the gas cooler, 30 is the expander, 31 is the evaporator, 32 is the water distributor, 33 is the fan coil unit, 34 is the water collector, 35 is the decontamination device, 36 is the chilled water pump, and 37 is the chiller.

[0031] As can be seen from the accompanying drawings, the present invention provides a power plant carbon capture system coupled with a refrigeration cycle to achieve cooling, comprising a power generation system of a coal-fired unit, a dry carbon dioxide capture system, a carbon dioxide post-processing system, a carbon dioxide refrigeration compression cycle system, and a chilled water circulation system;

[0032] The power generation system of the coal-fired unit includes a boiler 1, a flue gas treatment device 11, a steam turbine 2, a generator 3, a feedwater pump turbine 4, a condenser 5, a condensate pump 6, a low-pressure heater 7, a deaerator 8, a feedwater pump 9, a high-pressure heater 10 and their connecting pipes and valves;

[0033] The dry carbon dioxide capture system includes a booster fan 12, a carbonation reactor 13, a cyclone separator 14, a regeneration reactor 15, a regenerated adsorbent cooling bed 17, a regenerated mixed gas cooler 18, a circulating fan 16 and connecting pipes and valves;

[0034] The carbon dioxide post-treatment system includes a first heat exchanger 19, a cooling water pump 20, a cooling tower 21, a second heat exchanger 22, a compressor 23, an air-cooled condenser 26, a throttle valve 25, a third heat exchanger 24 and connecting pipes and valves thereof;

[0035] The carbon dioxide refrigeration cycle system includes an evaporator 31, a carbon dioxide-specific compressor 27, a high-temperature heat exchanger 28, a gas cooler 29, an expander 30, and connecting pipes and valves;

[0036] The chilled water circulation system includes a water distributor 32, a fan coil unit 33, a water collector 34, a dirt remover 35, a chilled water pump 36 and its connecting pipes and valves;

[0037] A portion of the condensate at the outlet of the condenser 4 is cooled by the refrigeration cycle evaporator 31, mixed with the cold water at the outlet of the chiller 37, and then fed into the fan coil unit 33. After heat exchange with the treated air, it passes through the water collector 34 and the decontaminator 35 for convergence and purification. The main stream of chilled water returns to the chiller 37, and its branch flows into the heat carrier pipeline of the carbonation reactor 13, taking away the heat released by the adsorption reaction to maintain the reaction temperature. The cooling heat released by the high-temperature solid adsorbent in the regenerated adsorbent cooling bed 17 is then used to complete the second heating. Finally, the third heating is achieved by heat exchange with the regenerated mixed gas.

[0038] The flue gas outlet of boiler 1 is connected to the inlet of flue gas treatment device 11 and the high-pressure cylinder of steam turbine 2. The outlet of intermediate-pressure cylinder of steam turbine 2 is connected to feedwater pump turbine 4. The low-pressure cylinder of steam turbine 2 is connected to generator 6 via flange. The exhaust steam outlet of low-pressure cylinder of steam turbine 2 and the exhaust steam outlet of feedwater pump turbine 4 are connected to condenser 4. Condenser 4 is connected to low-pressure heater 7 via condensate pump 5. Low-pressure heater 7 is connected to deaerator 8. Deaerator 8 is connected to high-pressure heater 10 via feedwater pump 9. High-pressure heater 10 is further connected to feedwater inlet of boiler 1.

[0039] The feedwater pump turbine 4 uses steam extracted from the intermediate pressure cylinder of the main steam turbine as its working fluid. Its exhaust steam mixes with the main steam and enters the condenser 5. The power generated is directly used to drive the feedwater pump 9. The flue gas treatment device is connected to the carbonation reactor 13 via a booster fan 12. The carbonation reactor 13 is connected to the cyclone separator 14. The cyclone separator 14 is connected to the regeneration reactor 15. The product outlet of the regeneration reactor 15 is connected to the circulation fan 16 at one end through the cyclone separator, and the other end is connected to the regenerated adsorbent cooling bed 17.

[0040] In the dry carbon dioxide capture system, the flue gas after desulfurization, denitrification and dust removal is pressurized by the booster fan 12 and then enters the carbonation reactor 13 to react with the highly active sodium-based solid adsorbent to remove CO2 in the flue gas; the adsorbent after the reaction is separated by the cyclone separator and a part of the mixed gas is discharged and then enters the regeneration reactor 15 through the circulating fan 16 for recycling. The high-temperature adsorbent after being regenerated by the extraction steam from the steam turbine 2 is cooled by the condensate return water and then returned to the carbonation reactor 13. A large part of the regenerated mixed gas at the outlet of the regeneration reactor 15 is used as the fluidizing medium, and the remaining part of the regenerated mixed gas enters the cooler to heat the extracted condensate return water.

[0041] The first heat exchanger 19 is connected to the second heat exchanger 22, the second heat exchanger 22 is connected to the compressor 23, and the compressor 23 is connected to the third heat exchanger 24 to form the mainstream flow of carbon dioxide;

[0042] The circulating cooling water providing cold for the first stage cooling passes through the first heat exchanger (19), the cooling water pump (20) and the cooling tower (21) in sequence to form a circulation. The refrigerant R717 providing cold for the third stage cooling passes through the third heat exchanger (23), the compressor, the air-cooled condenser (26) and the throttle valve (25) in sequence to form a refrigeration cycle. The refrigerant cycle providing cold for the second stage cooling is similar to the above refrigeration cycle.

[0043] The carbon dioxide gas pre-treated by the regenerative mixed gas cooler 18 in the carbon dioxide post-treatment system enters the first heat exchanger 19 and uses the cooling tower 21 to supply circulating cooling water to achieve the first stage of cooling. Then it enters the second heat exchanger 22 and uses the compression refrigeration cycle of the refrigerant R717 to achieve the second stage of cooling. After the primary cooling, the carbon dioxide gas enters the compressor 23 for pressurization, and finally completes the final cooling through heat absorption at the evaporation end of the refrigerant R717 refrigeration cycle.

[0044] The exhaust port of the dedicated carbon dioxide compressor 27 is connected to the high-temperature heat exchanger 28, the high-temperature heat exchanger 28 is connected to the gas cooler 29, the gas cooler 29 is connected to the expander 30, the exhaust port of the expander 30 is connected to the evaporator 31, and the evaporator 31 is connected to the air inlet of the dedicated carbon dioxide compressor 27 to form a cycle;

[0045] In the carbon dioxide compression refrigeration cycle, the secondary treated carbon dioxide gas is injected into compressor 27. After being compressed into a high-temperature, high-pressure supercritical state by compressor 27, the carbon dioxide gas enters high-temperature heat exchanger 28 to be cooled by circulating hot water, and then enters gas cooler 29 to be further cooled by cooling water. The high-pressure carbon dioxide gas at the outlet of gas cooler 29 is cooled and depressurized by expander 30, and then enters evaporator 31 to absorb a large amount of heat from the extracted condensate, and then vaporizes into superheated steam, which enters compressor 27 to increase the pressure. This cycle is repeated over and over again.

[0046] The chilled water supply port of the chiller 37 is connected to the water distributor 32, the water distributor 32 is connected to the fan coil unit 33, the fan coil unit 33 is connected to the water collector 34, the water collector 34 is connected to the decontaminator 35, the decontaminator 35 is connected to the chilled water pump 36, and the chilled water pump 36 is connected to the chilled water return port of the chiller 37.

[0047] The present invention is illustrated below by way of example:

[0048] A 300MW coal-fired unit was selected. It was assumed that the CO2 capture capacity of the unit accounted for 13.1% of the total CO2 emissions of the flue gas. The CO2 removal rate in the tail flue gas was still set at 90%. The adsorbent used was a highly active sodium-based solid adsorbent (70wt% Al2O3+30wt% Na2CO3).

[0049] In this system, the boiler 1, flue gas treatment device 11, steam turbine 2, generator 3, condenser 5, condensate pump 6, low-pressure heater 7, deaerator 8, feed water pump 9, high-pressure heater 10 and corresponding auxiliary equipment and pipelines constitute the power generation system; the booster fan 12, carbonation reactor 13, cyclone separator 14, regeneration reactor 15, regenerated adsorbent cooling bed 17, regenerated mixed gas cooler 18, circulating fan 16 and corresponding auxiliary equipment and pipelines constitute the dry carbon dioxide capture system; the carbon dioxide post-processing system mainly involves the first Heat exchanger 19, cooling water pump 20, cooling tower 21, second heat exchanger 22, compressor 23, air-cooled condenser 26, throttle valve 25, third heat exchanger 24 and their connecting pipes and valves; the carbon dioxide refrigeration cycle system mainly involves evaporator 31, carbon dioxide dedicated compressor 27, high-temperature heat exchanger 28, gas cooler 29, expander 30 and its connecting pipes and valves; and the chilled water circulation system mainly consists of water distributor 32, fan coil unit 33, water collector 34, desludger 35, chilled water pump 36 and its connecting pipes and valves.

[0050] In the dry CO2 capture system, a sodium-based solid adsorbent adsorbs CO2 from the flue gas in the carbonation reactor 13, maintaining the adsorption reaction temperature at 60°C. The CO2-adsorbed adsorbent is then fed into a cyclone separator 14, where it is separated from the remaining flue gas. The adsorbent then enters a regeneration reactor 15 for heating and regeneration at a temperature of 150°C. The regenerated adsorbent is too hot and must be cooled to 60°C in a regenerated adsorbent cooling bed 17 before entering the carbonation reactor 13 and being recycled into the carbonation reactor 14. A portion of the regenerated gas at the regeneration reactor outlet is separated and returned to the regeneration bed as a fluidizing medium, while the remaining gas enters a first heat exchanger 19 and a second heat exchanger 22 for initial cooling. After heat exchange, the regenerated gas enters a compressor 23, where it is pressurized to a charging pressure of 3.66 MPa. Finally, it is cooled again in a third heat exchanger 24 to produce a high-concentration CO2 refrigerant with a charging temperature of 7°C. This is higher than the temperature of liquefied CO2 required for tanker transportation, resulting in lower energy consumption for the cooling refrigeration unit.

[0051] Comparing the basic parameters of a 300MW unit of the same size, with the same CO2 capture capacity and steam extraction capacity, the relevant parameters are as follows:

[0052] Table 1: Comparison of main parameters of the system of the present invention and the control unit

[0053]

[0054] In this example, the proposed novel power plant carbon capture-coupled refrigeration cycle cooling system reduces power consumption during the compression process of the control unit while also providing both cooling and heating to end users through the introduction of a cooling system. This demonstrates the economic benefits of the novel system.

[0055] The technical means disclosed in the solution of the present invention are not limited to the technical means disclosed in the above technical means, but also include technical solutions composed of any combination of the above technical features.

[0056] With the above-described preferred embodiments of the present invention as inspiration, and with reference to the above description, relevant personnel are fully capable of making various changes and modifications without departing from the technical scope of this invention. The technical scope of this invention is not limited to the contents of the specification, but must be determined according to the scope of the claims.

Claims

1. A power plant carbon capture system coupled with a refrigeration cycle to provide cooling, characterized by: It includes the power generation system of coal-fired units, alkali metal-based dry carbon dioxide capture system, carbon dioxide post-processing system, carbon dioxide refrigeration compression cycle system and chilled water circulation system; The power generation system of the coal-fired unit comprises a boiler (1), a flue gas treatment device (11), a steam turbine (2), a generator (3), a feedwater pump turbine (4), a condenser (5), a condensate pump (6), a low-pressure heater (7), a deaerator (8), a feedwater pump (9), a high-pressure heater (10), and connecting pipes and valves thereof; The alkali metal-based dry carbon dioxide capture system comprises a booster fan (12), a carbonation reactor (13), a cyclone separator (14), a regeneration reactor (15), a regeneration adsorbent cooling bed (17), a regeneration mixed gas cooler (18), a circulation fan (16) and connecting pipes and valves thereof; The carbon dioxide post-processing system comprises a first heat exchanger (19), a cooling water pump (20), a cooling tower (21), a second heat exchanger (22), a compressor (23), an air-cooled condenser (26), a throttle valve (25), a third heat exchanger (24), and connecting pipes and valves thereof; The carbon dioxide refrigeration cycle system includes an evaporator (31), a carbon dioxide-specific compressor (27), a high-temperature heat exchanger (28), a gas cooler (29), an expander (30), and connecting pipes and valves thereof; The chilled water circulation system includes a water distributor (32), a fan coil unit (33), a water collector (34), a dirt remover (35), a chilled water pump (36) and connecting pipes and valves thereof; The condensate is used as a circulating working medium: the branch pipe at the outlet of the condenser (5) in the coal-fired unit power generation system is connected to the hot fluid inlet of the evaporator (31) in the carbon dioxide refrigeration cycle system, the hot fluid outlet of the evaporator (31) is connected to the water inlet joint of the water distributor (32) in the chilled water cycle system, the outlet of the chilled water pump (36) in the chilled water cycle system and the outlet of the condensate pump (6) in the coal-fired unit power generation system are connected to the heat carrier pipeline inlet of the carbonation reactor (13) in the alkali metal-based dry carbon dioxide capture system; the cold fluid outlet of the regenerated mixed gas cooler (18) in the alkali metal-based dry carbon dioxide capture system is connected to the cold fluid inlet of the low-pressure heater (7) in the coal-fired unit power generation system; The working medium acting on carbon dioxide is as follows: the outlet of the flue gas treatment device (11) in the coal-fired power generation system is connected to the inlet of the booster fan (12) in the carbon dioxide refrigeration cycle system, the hot fluid inlet of the regenerative mixed gas cooler (18) in the carbon dioxide refrigeration cycle system is connected, the hot fluid outlet of the regenerative mixed gas cooler (18) is connected to the hot fluid inlet of the first heat exchanger (19) in the carbon dioxide post-processing system, and the hot fluid outlet of the third heat exchanger (24) in the carbon dioxide post-processing system is connected to the refrigerant injection port of the carbon dioxide dedicated compressor (27) in the carbon dioxide refrigeration cycle system; The working process is as follows: a portion of the condensate at the outlet of the condenser (5) is cooled by the refrigeration cycle evaporator (31), mixed with the chilled water at the water supply port of the chiller (37), and then sent to the fan coil unit (33). After heat exchange with the treated air, it passes through the water collector (34) and the decontaminator (35) for convergence and purification. The main stream of chilled water returns to the chiller (37), and its branch flows into the heat carrier pipeline of the carbonation reactor (13), taking away the heat released by the adsorption reaction to maintain the reaction temperature. The cooling heat released by the high-temperature solid adsorbent in the regenerated adsorbent cooling bed (17) is then used to complete the second heating. Finally, the third heating is achieved by heat exchange with the regenerated mixed gas.

2. The power plant carbon capture system coupled with a refrigeration cycle to achieve cooling according to claim 1, characterized in that: The flue gas outlet of the boiler (1) is connected to the inlet of the flue gas treatment device (11) and the high-pressure cylinder of the steam turbine (2); an outlet of the intermediate-pressure cylinder of the steam turbine (2) is connected to the feedwater pump turbine (4); the low-pressure cylinder of the steam turbine (2) is connected to the generator (3) through a flange; the exhaust steam outlet of the low-pressure cylinder of the steam turbine (2) and the exhaust steam outlet of the feedwater pump turbine (4) are connected to the condenser (5); the condenser (5) is connected to the low-pressure heater (7) through a condensate pump (6); the low-pressure heater (7) is connected to the deaerator (8); the deaerator (8) is connected to the high-pressure heater (10) through a feedwater pump (9); and the high-pressure heater (10) is connected to the feedwater inlet of the boiler (1); The feedwater pump steam turbine (4) uses the extraction steam from the intermediate pressure cylinder of the main steam turbine as the working medium, and the exhaust steam is mixed with the main steam and enters the condenser (5). The generated power is directly used to drive the feedwater pump (9).

3. The power plant carbon capture system coupled with a refrigeration cycle to achieve cooling according to claim 1, characterized in that: The flue gas treatment device is connected to a carbonation reactor (13) via a booster fan (12), the carbonation reactor (13) is connected to a cyclone separator (14), the cyclone separator (14) is connected to a regeneration reactor (15), one end of a product outlet of the regeneration reactor (15) is connected to a circulation fan (16) via the cyclone separator, and the other end is connected to a regeneration adsorbent cooling bed (17); In an alkali metal-based dry carbon dioxide capture system, the flue gas after desulfurization, denitrification and dust removal treatment is pressurized by a booster fan (12) and then enters a carbonation reactor (13), where it reacts with a high-activity alkali metal-based solid adsorbent at a reaction temperature of 60°C to remove CO2 from the flue gas; the adsorbent after the reaction is separated into a portion of mixed gas by a cyclone separator and then enters a regeneration reactor (15) through a circulating fan (16) for recycling; the high-temperature adsorbent is heated to 150°C by exhaust steam from a steam turbine (2) to achieve regeneration and is then cooled by condensate return water and returned to the carbonation reactor (13); a large portion of the regenerated mixed gas at the outlet of the regeneration reactor (15) is used as a fluidizing medium, and the remaining portion of the regenerated mixed gas enters a regeneration mixed gas cooler (18) to heat the extracted condensate return water.

4. The power plant carbon capture system coupled with a refrigeration cycle to achieve cooling according to claim 1, characterized in that: The first heat exchanger (19) is connected to the second heat exchanger (22), the second heat exchanger (22) is connected to the compressor (23), and the compressor (23) is connected to the third heat exchanger (24) to form a mainstream flow of carbon dioxide; The circulating cooling water providing cold for the first stage cooling passes through the first heat exchanger (19), the cooling water pump (20) and the cooling tower (21) in sequence to form a circulation. The refrigerant R717 providing cold for the third stage cooling passes through the third heat exchanger (24), the compressor, the air-cooled condenser (26) and the throttle valve (25) in sequence to form a refrigeration cycle. The refrigerant cycle providing cold for the second stage cooling is similar to the above refrigeration cycle. The carbon dioxide gas pre-treated by the regenerative mixed gas cooler (18) in the carbon dioxide post-processing system enters the first heat exchanger (19) and uses the cooling tower (21) to supply circulating cooling water to achieve the first stage of cooling to 45°C, and then enters the second heat exchanger (22) to achieve the second stage of cooling to 0°C using the compression refrigeration cycle of the refrigerant R717. The carbon dioxide gas after the primary cooling enters the compressor (23) and is pressurized to 3.66MPa. At the same time, the temperature rises. Finally, the final cooling is completed by absorbing heat at the evaporation end of the refrigerant R717 refrigeration cycle, and a CO2 product with a filling temperature of 7°C is obtained.

5. The power plant carbon capture system coupled with a refrigeration cycle to achieve cooling according to claim 1, characterized in that: The exhaust port of the carbon dioxide dedicated compressor (27) is connected to the high-temperature heat exchanger (28), the high-temperature heat exchanger (28) is connected to the gas cooler (29), the gas cooler (29) is connected to the expander (30), the exhaust port of the expander (30) is connected to the evaporator (31), and the evaporator (31) is connected to the air inlet of the carbon dioxide dedicated compressor (27) to form a cycle; The carbon dioxide gas that has undergone secondary treatment in the carbon dioxide compression refrigeration cycle system is injected into a dedicated carbon dioxide compressor (27). After being compressed into a high-temperature, high-pressure supercritical state by the dedicated carbon dioxide compressor (27), the carbon dioxide gas enters a high-temperature heat exchanger (28) to be cooled by circulating hot water, and then enters a gas cooler (29) to be further cooled by cooling water. The high-pressure carbon dioxide gas at the outlet of the gas cooler (29) is cooled and depressurized by an expander (30), and then enters an evaporator (31) to absorb a large amount of heat from a portion of the extracted condensed water and vaporize into superheated steam, and then enters the dedicated carbon dioxide compressor (27) to increase the pressure, and this cycle is repeated over and over again.

6. The power plant carbon capture system coupled with a refrigeration cycle to achieve cooling according to claim 1, characterized in that: The chilled water supply port of the chiller (37) is connected to the water distributor (32), the water distributor (32) is connected to the fan coil unit (33), the fan coil unit (33) is connected to the water collector (34), the water collector (34) is connected to the dirt remover (35), the dirt remover (35) is connected to the chilled water pump (36), and the chilled water pump (36) is connected to the chilled water return port of the chiller (37).

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