A gas-distributed coupled supercritical CO2 Brayton cycle power generation zero-carbon device and method

Abstract

The present invention relates to the field of low-temperature waste heat power generation and clean production technology, and in particular to a gas-fired distributed coupled supercritical CO2 Brayton cycle power generation zero-carbon device and method, the device comprising a gas-fired distributed power generation system, a supercritical CO2 Brayton cycle power generation system, a low-temperature flue gas waste heat deep recovery and utilization system, and a CO2 capture system. Based on the thermodynamic advantages of the natural working fluid CO2, the present invention couples the supercritical CO2 Brayton cycle power generation system with the gas-fired distributed power generation system, connects the flue gas low-temperature waste heat deep utilization system and the CO2 capture system in series, recovers the sensible heat and latent heat of the flue gas, and achieves the dual goals of improving energy utilization and zero carbon emissions. Gas-fired power generation coupled with a supercritical CO2 Brayton cycle improves the power generation efficiency of the distributed gas system; the heat pump is used to absorb the low-temperature heat of the circulating cooling water to recover the heat dissipation of the air compressor and the cooler; the flue gas is utilized in multiple stages, and more than 75% of the total heat of the flue gas is recovered, achieving deep recovery of the flue gas waste heat.

Description

Technical Field

[0001] The present invention relates to the technical field of low-temperature power generation and clean production, and in particular to a gas-distributed coupled supercritical CO2 Brayton cycle zero-carbon power generation device and method. Background Art

[0002] Flue gas waste heat recovery is one of the main ways to improve the efficiency of fossil energy utilization. At present, in gas-fired distributed power generation systems at home and abroad, flue gas waste heat recovery is through a gas-steam combined cycle system. High-temperature flue gas enters the waste heat boiler, and the waste heat boiler generates high-temperature steam to drive the steam turbine to generate electricity. The shortcomings of this cycle are: the temperature matching between water and high-temperature flue gas is poor during the heat exchange process, and the heat loss is large; water vapor is a wet fluid. In order to prevent liquid hammer in the steam turbine, it must have a large superheat, which will lead to an excessively large superheater area; the volume specific work of the water vapor expansion process is small, and a larger turbine size or a higher speed has to be used, thereby increasing the system cost; the exhaust temperature must be at least 10°C higher than the flue gas dew point temperature, and the lowest can only be reduced to 80-90°C. There is a lot of water vapor in the flue gas, and the flue gas dew point temperature is generally between 40 and 50°C. Due to the limitation of the exhaust temperature, the latent heat of this part of water vapor cannot be used, and the flue gas waste heat recovery is incomplete. Summary of the invention

[0003] The purpose of the present invention is to provide a gas-distributed coupled supercritical CO2 Brayton cycle zero-carbon power generation device and method, which can solve the above-mentioned technical problems.

[0004] The present invention provides a gas-fired distributed coupled supercritical CO2 Brayton cycle power generation zero-carbon device, comprising a gas-fired distributed power generation system, a supercritical CO2 Brayton cycle power generation system, a low-temperature flue gas waste heat deep recovery and utilization system, and a CO2 capture system;

[0005] The gas-fired distributed power generation system comprises an air compressor, a combustion chamber and a gas turbine connected in sequence;

[0006] The supercritical CO2 Brayton cycle power generation system includes a high-pressure turbine, a low-pressure turbine, a first heater, a second heater, a first compressor, a second compressor, a high-temperature regenerator, a low-temperature regenerator and a cooler;

[0007] The low-temperature flue gas waste heat deep recovery and utilization system comprises a two-stage gas-liquid plate-shell heat exchanger, a heat pump and a user end;

[0008] The CO2 capture system includes a decarbonization absorption tower, a regeneration tower and a CO2 storage tank;

[0009] The flue gas outlet of the gas turbine is connected to the inlet of the first heater through a pipeline, the outlet of the first heater is connected to the inlet of the second heater through a pipeline, and the outlet of the second heater is connected to the inlet of the regeneration tower through a pipeline;

[0010] The outlet of the cooler is divided into two paths, one of which is connected to the inlet of the high-pressure turbine through the first compressor, the low-temperature regenerator, the high-temperature regenerator and the first heater, and the other is connected to the inlet of the low-pressure turbine through the second compressor and the second heater. The outlet of the high-pressure turbine is connected to the inlet of the cooler through the high-temperature regenerator and the low-temperature regenerator, and the outlet of the low-pressure turbine is connected to the inlet of the cooler through the low-temperature regenerator;

[0011] The outlet of the regeneration tower is connected to the inlet of the two-stage gas-liquid plate-shell heat exchanger through a pipeline, the outlet of the two-stage gas-liquid plate-shell heat exchanger is connected to the inlet of the decarbonization absorption tower, the outlet of the decarbonization absorption tower is connected to the regeneration tower, and the regeneration tower is connected to the inlet of the CO2 storage tank through a pipeline;

[0012] The first stage heat exchange of the two-stage gas-liquid plate and shell heat exchanger is connected to the user end through an inlet pipe and a return pipe, and the second stage heat exchange of the two-stage gas-liquid plate and shell heat exchanger is connected to a heat pump through an inlet pipe and a return pipe, and the heat pump is connected to the user end through an inlet pipe and a return pipe.

[0013] Preferably, a cold water coil is provided inside the air compressor, the outlet of the cold water coil is connected to the low-temperature heat source inlet of the heat pump through a pipeline, and the circulating cooling water outlet of the heat pump is connected to the inlet of the cold water coil through a pipeline.

[0014] Preferably, the cooling water outlet of the cooler is connected to the low-temperature heat source inlet of the heat pump through a pipeline.

[0015] The present invention also provides a zero-carbon method for power generation by gas-distributed coupling supercritical CO2 Brayton cycle, which is applied to the above system and comprises:

[0016] S1. Gas-fired distributed power generation system, which compresses air and gas into the burner to drive the gas turbine to drive the generator to generate electricity and be connected to the power grid;

[0017] S2. Supercritical CO2 Brayton cycle power generation system, high-temperature flue gas drives supercritical CO2 fluid through two-stage compression to drive high and low pressure turbine expansion to drive the generator to generate electricity and be connected to the power grid;

[0018] S3. Low-temperature flue gas waste heat deep recovery and utilization system, low-temperature flue gas is heat exchanged through a two-stage gas-liquid plate and shell heat exchanger, the hot water produced in the first stage is directly supplied to users, and the low-temperature hot water produced in the second stage is supplied to users after being lifted by a heat pump;

[0019] S4.CO2 capture system, low-temperature flue gas enters the absorption tower for decarbonization and then enters the regeneration tower, where it is recovered after heating and enters the CO2 storage tank for reuse.

[0020] Preferably, in step S1, the air compressor compresses the air and sends it into the combustion chamber to burn with the natural gas injected at the same time. The generated high-temperature flue gas expands and does work, driving the impeller to rotate, converting part of its thermal energy into mechanical energy, driving the generator to generate electricity, and the flue gas at 450-600°C after doing work enters the supercritical CO2 Brayton cycle power generation system.

[0021] Preferably, in step S1, the air compressor generates a large amount of heat during operation. This heat is collected by arranging a cold water coil inside the air compressor, and the cooling water is heated from 32°C to 37°C. The water enters the heat pump unit as a low-temperature heat source for the heat pump to produce hot water for the user end.

[0022] Preferably, in step S2, the CO2 fluid at the outlet of the cooler is divided into two parts, one part of which enters the first compressor to be compressed to a higher pressure, and then is heated three times in sequence through the high-pressure side of the low-temperature regenerator, the high-pressure side of the high-temperature regenerator, and the first heater. The heated high-temperature and high-pressure CO2 fluid expands in the high-pressure turbine to drive the generator to generate electricity; the other part of the fluid enters the second compressor to be compressed to a medium pressure, and then further absorbs the heat of the flue gas in the second heater, and then expands through the low-pressure turbine to do work, and finally merges with the CO2 fluid on the low-pressure side of the high-temperature regenerator to enter the low-temperature heater to recover waste heat, and then enters the cooler for further cooling, wherein the heat of the cooler is taken away by cooling water, and the cooling water is heated from 32°C to 37°C, and the cooling water of the cooler and the cooling water of the air compressor merge into the heat pump unit as the low-temperature heat source of the heat pump to produce hot water for supply to the user end.

[0023] Preferably, in step S3, the flue gas discharged from the regeneration tower of the CO2 capture system enters a two-stage gas-liquid plate and shell heat exchanger, the first-stage flue gas is cooled from 130°C to 65°C, and the air-conditioning hot water is simultaneously heated from 50°C to 60°C for user use; the second-stage flue gas is cooled from 65°C to 35°C, and the circulating cooling water is heated from 32°C to 37°C, and merged with the air compressor cooling water and the cooler cooling water to enter the heat pump unit as a low-temperature heat source for the heat pump to produce hot water for supply to the user end.

[0024] Preferably, in step S4, the exhaust temperature of the two-stage gas-liquid plate and shell heat exchanger is between 30 and 40°C, and the exhaust gas enters the decarbonization absorption tower. The alkaline absorbent in the absorption tower absorbs CO2 in the flue gas and then enters the regeneration tower. The reboiler in the regeneration tower is heated to 100 to 120°C by the flue gas, so that the CO2 in the absorbent solution is released, thereby finally achieving the separation and recovery of CO2.

[0025] Preferably, the heat source of the reboiler in the regeneration tower comes from the flue gas emitted by the supercritical CO2 Brayton cycle power generation system.

[0026] Beneficial effects:

[0027] Based on the thermodynamic advantages of the natural working fluid CO2, the present invention couples the supercritical CO2 Brayton cycle to generate electricity through the gas-fired distributed power generation system, connects the flue gas low-temperature waste heat deep utilization system and the CO2 capture system in series, recovers the sensible heat and latent heat of the flue gas, and achieves the dual goals of improving energy utilization and zero carbon emissions. The gas-fired power generation system coupled with the supercritical CO2 Brayton cycle improves the power generation efficiency of the traditional distributed gas system; the heat pump absorbs the low-temperature heat of the circulating cooling water, recovers the waste heat of the air compressor, cooler and other equipment, and plays a role in energy conservation and environmental protection; the flue gas is utilized in multiple stages, and the final emission temperature reaches about 30 to 40°C, recovering more than 75% of the total heat of the flue gas. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] In order to more clearly illustrate the specific implementation methods of the present invention or the technical solutions in the prior art, the drawings required for use in the specific implementation methods or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are some implementation methods of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0029] Figure 1 It is a schematic diagram of the overall structure of the system of the present invention;

[0030] Figure 2 It is a schematic diagram of the process flow of the method of the present invention.

[0031] Explanation of the reference numerals: 1-air compressor, 2-combustion chamber, 3-gas turbine, 4-high-pressure turbine, 5-low-pressure turbine, 601-first heater, 602-second heater, 701-first compressor, 702-second compressor, 8-high-temperature regenerator, 9-low-temperature regenerator, 10-cooler, 11-decarbonization absorption tower, 12-regeneration tower, 13-CO2 storage tank, 14-two-stage gas-liquid plate and shell heat exchanger, 15-heat pump, 16-user end. DETAILED DESCRIPTION

[0032] The technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the described embodiments are part of the embodiments of the present invention, rather than 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.

[0033] In the description of the present invention, it should be understood that the terms "center", "longitudinal", "lateral", "length", "width", "thickness", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside", "clockwise", "counterclockwise" and the like indicate orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, rather than indicating or implying that the referred device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as limiting the present invention.

[0034] In addition, the terms "first" and "second" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features. In the description of the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined. In addition, the terms "installed", "connected" and "connected" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal connection of two elements. For those of ordinary skill in the art, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0035] Example 1

[0036] A gas-fired distributed coupled supercritical CO2 Brayton cycle power generation zero-carbon device, comprising a gas-fired distributed power generation system, a supercritical CO2 Brayton cycle power generation system, a low-temperature flue gas waste heat deep recovery and utilization system, and a CO2 capture system;

[0037] like Figures 1-2 As shown, the gas-fired distributed power generation system includes an air compressor 1, a combustion chamber 2, a gas turbine 3 and a generator which are connected in sequence.

[0038] The supercritical CO2 Brayton cycle power generation system includes a high-pressure turbine 4, a low-pressure turbine 5, a first heater 601, a second heater 602, a first compressor 701, a second compressor 702, a high-temperature regenerator 8, a low-temperature regenerator 9 and a cooler 10; the flue gas outlet of the gas turbine 3 is connected to the inlet of the first heater 601 through a pipeline, the outlet of the first heater 602 is connected to the inlet of the second heater 602 through a pipeline, and the outlet of the second heater 602 is connected to the inlet of the regeneration tower 12 through a pipeline; the outlet of the cooler 10 is divided into two routes, one route is connected to the inlet of the high-pressure turbine 4 through the first compressor 701, the low-temperature regenerator 9, the high-temperature regenerator 8 and the first heater 601, and the other route is connected to the inlet of the low-pressure turbine 5 through the second compressor 702 and the second heater 602, the outlet of the high-pressure turbine 4 is connected to the inlet of the cooler 10 through the high-temperature regenerator 8 and the low-temperature regenerator 9, and the outlet of the low-pressure turbine 5 is connected to the inlet of the cooler 10 through the low-temperature regenerator 9.

[0039] The CO2 capture system includes a decarbonization absorption tower 11, a regeneration tower 12 and a CO2 storage tank 13. The outlet of the regeneration tower 12 is connected to the inlet of a two-stage gas-liquid plate and shell heat exchanger 14 through a pipeline, the outlet of the two-stage gas-liquid plate and shell heat exchanger 14 is connected to the inlet of the decarbonization absorption tower 11, the outlet of the decarbonization absorption tower 11 is connected to the regeneration tower 12, and the regeneration tower 12 is connected to the inlet of the CO2 storage tank 13 through a pipeline.

[0040] The low-temperature flue gas waste heat deep recovery and utilization system includes a two-stage gas-liquid plate and shell heat exchanger 14, a heat pump 15 and a user end 16; the first heat exchange stage of the two-stage gas-liquid plate and shell heat exchanger 14 is connected to the user end 16 through a water inlet pipe and a return pipe, the second heat exchange stage of the two-stage gas-liquid plate and shell heat exchanger 14 is connected to the heat pump 15 through a water inlet pipe and a return pipe, and the heat pump 15 is connected to the user end 16 through a water inlet pipe and a return pipe.

[0041] In addition, a cold water coil is provided inside the air compressor, the outlet of the cold water coil is connected to the low-temperature heat source inlet of the heat pump through a pipeline, and the circulating cooling water outlet of the heat pump is connected to the inlet of the cold water coil through a pipeline. The cooling water outlet of the cooling pump is connected to the low-temperature heat source inlet of the heat pump through a pipeline.

[0042] The air compressor 1 compresses the air and sends it into the combustion chamber 2, where it burns with the natural gas injected at the same time. The high-temperature flue gas generated expands and does work, driving the impeller to rotate, converting part of its thermal energy into mechanical energy, driving the generator to generate electricity. The flue gas after work, generally 450-600℃, enters the supercritical CO2 Brayton cycle power generation system.

[0043] The air compressor generates a lot of heat during operation, which mainly comes from the compression process, mechanical friction and motor heating. The traditional practice is to discharge this heat into the environment through the cooling system, causing energy waste and thermal pollution. Here, this part of the heat is collected by setting a cold water coil inside the air compressor, and the cooling water is heated from 32°C to 37°C and enters the heat pump unit as a low-temperature heat source for the heat pump to produce 60°C hot water for users.

[0044] The CO2 fluid at the outlet of the cooler 10 is divided into two parts, one of which enters the first compressor 701 to be compressed to a higher pressure, and then is heated three times in sequence by passing through the high-pressure side of the low-temperature regenerator, the high-pressure side of the high-temperature regenerator, and the first heater. The heated high-temperature and high-pressure CO2 fluid expands and works in the high-pressure turbine 4 to drive the generator to generate electricity; the other part enters the second compressor 702 to be compressed to a medium pressure, and then further absorbs the heat of the flue gas in the second heater 602, and then expands and works through the low-pressure turbine 5, and finally merges with the CO2 fluid on the high-pressure side of the high-temperature regenerator to enter the low-temperature heater 9 to recover the waste heat and then enter the cooler 10 for further cooling. The heat of the cooler 10 is taken away by the cooling water, which is heated from 32°C to 37°C, and merges with the cooling water of the air compressor 1 to enter the heat pump 15 unit as the low-temperature heat source of the heat pump to produce 60°C hot water for users.

[0045] The flue gas discharged from the reboiler in the regeneration tower 12 of the CO2 capture system is about 130℃ and enters the two-stage gas-liquid plate and shell heat exchanger 14. The first-stage flue gas is cooled from 130℃ to 65℃, and the air conditioning hot water is heated from 50℃ to 60℃ for users. The second-stage flue gas is cooled from 65℃ to 35℃ (between 30℃ and 40℃), and the circulating cooling water is heated from 32℃ to 37℃, and merged with the air compressor cooling water and the cooler cooling water to enter the heat pump unit as the low-temperature heat source of the heat pump to produce 60℃ hot water for users.

[0046] The exhaust gas temperature of the two-stage gas-liquid plate-shell heat exchanger 14 is between 30 and 40°C, and the exhaust gas enters the decarbonization absorption tower 11. The alkaline absorbent in the absorption tower absorbs CO2 in the flue gas and then enters the regeneration tower 12. In the regeneration tower 12, the reboiler is heated by the flue gas to about 100 to 120°C, so that the CO2 in the absorbent solution is released, and finally the CO2 is separated and recovered. The heat source of the reboiler comes from the flue gas at about 150°C emitted by the supercritical CO2 Brayton cycle power generation system.

[0047] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or replace some or all of the technical features therein with equivalents. However, these modifications or replacements 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 gas-fired distributed coupled supercritical CO2 Brayton cycle power generation zero-carbon device, characterized in that: Including gas-fired distributed power generation system, supercritical CO2 Brayton cycle power generation system, low-temperature flue gas waste heat deep recovery and utilization system and CO2 capture system; The gas-fired distributed power generation system comprises an air compressor, a combustion chamber and a gas turbine connected in sequence; The supercritical CO2 Brayton cycle power generation system includes a high-pressure turbine, a low-pressure turbine, a first heater, a second heater, a first compressor, a second compressor, a high-temperature regenerator, a low-temperature regenerator and a cooler; The low-temperature flue gas waste heat deep recovery and utilization system comprises a two-stage gas-liquid plate-shell heat exchanger, a heat pump and a user end; The CO2 capture system includes a decarbonization absorption tower, a regeneration tower and a CO2 storage tank; The flue gas outlet of the gas turbine is connected to the inlet of the first heater through a pipeline, the outlet of the first heater is connected to the inlet of the second heater through a pipeline, and the outlet of the second heater is connected to the inlet of the regeneration tower through a pipeline; The outlet of the cooler is divided into two paths, one of which is connected to the inlet of the high-pressure turbine through the first compressor, the low-temperature regenerator, the high-temperature regenerator and the first heater, and the other is connected to the inlet of the low-pressure turbine through the second compressor and the second heater. The outlet of the high-pressure turbine is connected to the inlet of the cooler through the high-temperature regenerator and the low-temperature regenerator, and the outlet of the low-pressure turbine is connected to the inlet of the cooler through the low-temperature regenerator; The outlet of the regeneration tower is connected to the inlet of the two-stage gas-liquid plate-shell heat exchanger through a pipeline, the outlet of the two-stage gas-liquid plate-shell heat exchanger is connected to the inlet of the decarbonization absorption tower, the outlet of the decarbonization absorption tower is connected to the regeneration tower, and the regeneration tower is connected to the inlet of the CO2 storage tank through a pipeline; The first stage heat exchange of the two-stage gas-liquid plate and shell heat exchanger is connected to the user end through an inlet pipe and a return pipe, and the second stage heat exchange of the two-stage gas-liquid plate and shell heat exchanger is connected to a heat pump through an inlet pipe and a return pipe, and the heat pump is connected to the user end through an inlet pipe and a return pipe.

2. The gas-fired distributed coupled supercritical CO2 Brayton cycle power generation zero-carbon device according to claim 1 is characterized in that: A cold water coil is provided inside the air compressor, the outlet of the cold water coil is connected to the low-temperature heat source inlet of the heat pump through a pipeline, and the circulating cooling water outlet of the heat pump is connected to the inlet of the cold water coil through a pipeline.

3. The gas-fired distributed coupled supercritical CO2 Brayton cycle power generation zero-carbon device according to claim 1 is characterized in that: The cooling water outlet of the cooler is connected to the low-temperature heat source inlet of the heat pump through a pipeline.

4. A zero-carbon method for power generation by gas-distributed coupling supercritical CO2 Brayton cycle, characterized in that: The method is applied to the system as claimed in claim 3, and the method comprises: S1. Gas-fired distributed power generation system, which compresses air and gas into the burner to drive the gas turbine to drive the generator to generate electricity and be connected to the power grid; S2. Supercritical CO2 Brayton cycle power generation system, high-temperature flue gas drives supercritical CO2 fluid through two-stage compression to drive high and low pressure turbine expansion to drive the generator to generate electricity and be connected to the power grid; S3. Low-temperature flue gas waste heat deep recovery and utilization system, low-temperature flue gas is heat exchanged through a two-stage gas-liquid plate and shell heat exchanger, the hot water produced in the first stage is directly supplied to users, and the low-temperature hot water produced in the second stage is supplied to users after being lifted by a heat pump; S4.CO2 capture system, low-temperature flue gas enters the absorption tower for decarbonization and then enters the regeneration tower, where it is recovered after heating and enters the CO2 storage tank for reuse.

5. The method according to claim 4, characterized in that In step S1, the air compressor compresses the air and sends it into the combustion chamber to burn with the natural gas injected at the same time. The generated high-temperature flue gas expands and does work, driving the impeller to rotate, converting part of its thermal energy into mechanical energy, driving the generator to generate electricity, and the flue gas at 450-600°C after doing work enters the supercritical CO2 Brayton cycle power generation system.

6. The method according to claim 4, characterized in that In step S1, the air compressor generates a large amount of heat during operation. This heat is collected by setting a cold water coil inside the air compressor, and the cooling water is heated from 32°C to 37°C. The water enters the heat pump unit as a low-temperature heat source for the heat pump to produce hot water for the user end.

7. The method according to claim 4, characterized in that In step S2, the CO2 fluid at the outlet of the cooler is divided into two parts, one part of which enters the first compressor to be compressed to a higher pressure, and then is heated three times in sequence through the high-pressure side of the low-temperature regenerator, the high-pressure side of the high-temperature regenerator, and the first heater. The heated high-temperature and high-pressure CO2 fluid expands and works in the high-pressure turbine to drive the generator to generate electricity; the other part of the fluid enters the second compressor to be compressed to a medium pressure, and then further absorbs the heat of the flue gas in the second heater, and then expands and works through the low-pressure turbine, and finally merges with the CO2 fluid on the low-pressure side of the high-temperature regenerator to enter the low-temperature heater to recover the waste heat, and then enters the cooler for further cooling, wherein the heat of the cooler is taken away by cooling water, and the cooling water is heated from 32°C to 37°C, and the cooling water of the cooler and the cooling water of the air compressor merge into the heat pump unit as the low-temperature heat source of the heat pump to produce hot water for supply to the user end.

8. The method according to claim 4, characterized in that In step S3, the flue gas discharged from the regeneration tower of the CO2 capture system enters the two-stage gas-liquid plate and shell heat exchanger, the first-stage flue gas is cooled from 130°C to 65°C, and the air-conditioning hot water is simultaneously heated from 50°C to 60°C for user use; the second-stage flue gas is cooled from 65°C to 35°C, and the circulating cooling water is heated from 32°C to 37°C, and merged with the air compressor cooling water and the cooler cooling water into the heat pump unit as the low-temperature heat source of the heat pump to produce hot water for the user end.

9. The method according to claim 4, characterized in that In step S4, the exhaust gas temperature of the two-stage gas-liquid plate and shell heat exchanger is between 30 and 40°C, and the exhaust gas enters the decarbonization absorption tower. The alkaline absorbent in the absorption tower absorbs CO2 in the flue gas and then enters the regeneration tower. The reboiler in the regeneration tower is heated to 100 to 120°C by the flue gas, so that the CO2 in the absorbent solution is released, and finally the CO2 is separated and recovered.

10. The method according to claim 9, characterized in that The heat source of the reboiler comes from the flue gas discharged from the supercritical CO2 Brayton cycle power generation system.

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