Coal supercritical water gasification power generation system coupled with supercritical carbon dioxide cycle and operation method

Abstract

The application discloses a coal supercritical water gasification power generation system coupled with a supercritical carbon dioxide cycle and an operation method, and the system comprises a supercritical water gasification unit, a power generation unit and a cooling carbon capture unit; the application realizes efficient, clean and low-carbon power generation of coal based on the supercritical water gasification technology; after being cooled and separated, a part of high-concentration carbon dioxide enters a regenerator to recover exhaust heat of a turbine, and is recycled to a combustor to control the inlet temperature of the turbine; the remaining carbon dioxide can be completely captured; by coupling the supercritical carbon dioxide cycle at a hot flow end of the system, the waste heat of gasification synthesis gas and turbine exhaust can be fully recovered, and efficient matching of the waste heat of the system can be realized; by reasonably distributing the gasification synthesis gas and the supercritical carbon dioxide working medium in the system, the heat exchange temperature difference of the heat exchanger at the cold end and the heat transfer irreversible loss can be effectively reduced, and the power generation efficiency of the system is improved.

Description

Technical Field

[0001] This invention relates to the field of efficient, clean, and low-carbon coal power generation technology, specifically to a coal supercritical water gasification power generation system coupled with a supercritical carbon dioxide cycle and its operation method. Background Technology

[0002] Supercritical water gasification technology converts the chemical energy of coal into hydrogen-rich syngas, enabling the cascade utilization of coal. It has advantages such as low gasification temperature, high hydrogen production rate, easy deposition of nitrogen and sulfur elements, and easy carbon capture, and is a potential technological foundation for efficient and low-carbon emissions from coal-fired power plants.

[0003] Currently, most coal-fired power generation systems built on supercritical water gasification technology rely on circulating water as the working fluid or recover waste heat through steam Rankine cycles. However, the supercritical water heating process in these systems suffers from significant heat transfer irreversibility due to heat source mismatch. To reduce irreversible losses during heat exchange and achieve efficient matching of system waste heat, it is necessary to explore novel power cycles integrated with supercritical water gasification systems.

[0004] Compared to the conventional steam Rankine cycle, the supercritical carbon dioxide Brayton cycle has a higher energy conversion efficiency and great application potential in coal-fired power generation. Therefore, it is urgent to explore technical routes that couple supercritical carbon dioxide power cycles with supercritical coal water gasification power generation systems to realize the technological advantages of efficient, clean, and low-carbon power generation from supercritical coal water gasification. Summary of the Invention

[0005] To achieve efficient, clean, and low-carbon coal power generation, this invention provides a coal supercritical water gasification power generation system coupled with a supercritical carbon dioxide cycle and its operation method. This system fully recovers the waste heat from gasification syngas and turbine exhaust by coupling a supercritical carbon dioxide cycle at the heat flow end, achieving efficient matching of system waste heat, effectively reducing the heat exchange temperature difference between the hot and cold ends of the heat exchanger and irreversible heat transfer losses, and improving the power generation efficiency of the system.

[0006] To achieve the above objectives, the present invention adopts the following technical solution.

[0007] A coal supercritical water gasification power generation system coupled with a supercritical carbon dioxide cycle, the system comprising a supercritical water gasification unit, a power generation unit, and a cooling carbon capture unit;

[0008] The supercritical water gasification unit includes a feedwater pump 1, a low-temperature preheater 2, a medium-temperature preheater 3, a high-temperature preheater 4, a supercritical water gasifier 5, a first heater 6, and a first gas-liquid separator 7. The gasification feedwater passes through the feedwater pump 1, sequentially through the cold ends of the low-temperature preheater 2, the medium-temperature preheater 3, and the high-temperature preheater 4, and then connects to the inlet of the supercritical water gasifier 5. Coal and oxygen are connected to the inlet of the supercritical water gasifier 5. Ash is discharged from the supercritical water gasifier 5. Syngas exits the supercritical water gasifier 5 and sequentially passes through the hot ends of the high-temperature preheater 4, the medium-temperature preheater 3, and the low-temperature preheater 2. Part of the syngas from the hot end outlet of the high-temperature preheater 4 enters the hot end inlet of the first heater 6. The hot end outlet of the first heater 6 mixes with the hot end outlet of the medium-temperature preheater 3 and enters the hot end inlet of the low-temperature preheater 2. The hot end outlet of the low-temperature preheater 2 is connected to the inlet of the first gas-liquid separator 7.

[0009] The power generation unit includes a burner 8, a gas turbine 9, a regenerator 10, a second heater 11, a precooler 14, a compressor 15, a low-temperature regenerator 16, and a high-pressure turbine 17. Oxygen and the syngas from the outlet of the first gas-liquid separator 7 are connected to the inlet of the burner 8. Part of the carbon dioxide separated by the system passes through the cold end of the regenerator 10 and then connects to the inlet of the burner 8. The product from the outlet of the burner 8 is connected to the gas turbine 9 to generate electricity, and then passes through the hot end of the regenerator 10 and the second heater 11 in sequence. In the integrated supercritical carbon dioxide power generation cycle, the carbon dioxide working fluid from the outlet of the precooler 14 is split into two paths after passing through the compressor 15: the first path is connected to the cold end of the low-temperature regenerator 16 and the first heater 6 in sequence, and the second path is connected to the cold end of the second heater 11. Finally, the two carbon dioxide working fluids are connected to the high-pressure turbine 17 to generate electricity, and then pass through the hot end of the low-temperature regenerator 16 and enter the precooler 14, completing a closed supercritical carbon dioxide power generation cycle.

[0010] The cooling carbon capture unit includes an exhaust cooler 12 and a second gas-liquid separator 13; the hot end outlet of the second heater 11 is connected to the inlet of the second gas-liquid separator 13 through the exhaust cooler 12 to separate carbon dioxide in the gas phase and water in the liquid phase; part of the carbon dioxide at the gas phase outlet of the second gas-liquid separator 13 is recycled back into the system through the burner 8, and the remaining carbon dioxide is completely captured.

[0011] The supercritical water gasifier 5 operates at a temperature of 500℃-800℃ and a pressure of 23MPa-32MPa.

[0012] Oxygen is split into two streams. One stream of oxygen enters the supercritical water gasifier 5, where it undergoes a partial oxidation supercritical water gasification reaction with the coal and gasification feedwater. The heat released is just enough to provide the heat required for the gasification reaction. The other stream of oxygen enters the burner 8, where it undergoes a complete oxidation reaction with the syngas. The main components of the product at the outlet of the burner 8 are carbon dioxide and water.

[0013] After the system is cooled and separated, part of the carbon dioxide is preheated by the regenerator 10 and then recirculated into the burner 8 as the cooling gas for the gas turbine 9. The inlet temperature of the gas turbine 9 is adjusted by changing the flow rate of the recirculated carbon dioxide working fluid.

[0014] The inlet temperature of the gas turbine 9 is 1000℃-1600℃, and the inlet pressure is 1.5MPa-3MPa.

[0015] The exhaust pressure of the high-pressure turbine 17 is 7.6MPa-8.5MPa.

[0016] The temperature of the working fluid at the outlet of the precooler 14 is 31℃-38℃.

[0017] The supercritical carbon dioxide working fluid at the outlet of the compressor 15 is split into two paths: the first path first enters the low-temperature regenerator 16 for preheating, and then enters the first heater 6 to recover the waste heat of the syngas; the second path enters the second heater 11 to recover the exhaust waste heat of the turbine. Through the reasonable splitting of the working fluid at the outlet of the compressor 15, the minimum heat exchange temperature difference between the low-temperature regenerator 16, the first heater 6 and the second heater 11 is 5℃-15℃.

[0018] The operation method of the coal supercritical water gasification power generation system coupled with supercritical carbon dioxide cycle is as follows: Gasification feedwater, after passing through feedwater pump 1, is preheated sequentially through the cold ends of low-temperature preheater 2, medium-temperature preheater 3, and high-temperature preheater 4. The preheated gasification feedwater, along with coal and oxygen, enters the supercritical water gasifier 5, where a partially oxidized supercritical water gasification reaction occurs. Ash is discharged from the outlet of the supercritical water gasifier 5 through an ash discharge pipe. Syngas from the outlet of the supercritical water gasifier 5 sequentially passes through the hot ends of the high-temperature preheater 4, medium-temperature preheater 3, and low-temperature preheater 2 to preheat the gasification feedwater. Part of the syngas from the hot end outlet of the high-temperature preheater 4 enters the hot end inlet of heater 6. The syngas from the hot end outlet of heater 6 mixes with the syngas from the hot end outlet of the medium-temperature preheater 3 and enters the hot end inlet of the low-temperature preheater 2. The syngas from the hot end outlet of the low-temperature preheater 2 enters the gas-liquid separator. Gas-liquid separation is performed in separator 7; oxygen and syngas from the outlet of separator 7 enter combustor 8; part of the separated carbon dioxide is preheated at the cold end of regenerator 10 before entering combustor 8; the product from combustor 8 enters gas turbine 9 to generate electricity; the turbine exhaust from gas turbine 9 enters the hot end inlet of regenerator 10 to preheat the circulating carbon dioxide working fluid; the working fluid from the hot end outlet of regenerator 10 enters the hot end inlet of heater 11 to further recover waste heat from turbine exhaust; the working fluid from the hot end outlet of heater 11 enters exhaust cooler 12 for cooling, and then enters gas-liquid separator 13 to separate gaseous carbon dioxide and liquid water; part of the carbon dioxide from the gaseous outlet of gas-liquid separator 13 is preheated at regenerator 10 and then circulated back into combustor 8, achieving complete carbon capture of the remaining carbon dioxide.

[0019] In the integrated supercritical carbon dioxide power generation cycle, the carbon dioxide working fluid from the outlet of the precooler 14 enters the compressor 15 for pressurization. The pressurized supercritical carbon dioxide working fluid is split into two paths: the first path enters the low-temperature regenerator 16 for preheating, and then enters the first heater 6 to recover the waste heat of the syngas; the second path enters the second heater 11 to recover the waste heat of the turbine exhaust. The working fluids from the outlets of the first heater 6 and the second heater 11 are mixed and enter the high-pressure turbine 17 to generate electricity. The working fluid from the outlet of the high-pressure turbine 17 enters the hot end inlet of the low-temperature regenerator 16, and then enters the precooler 14 for cooling, completing a closed loop.

[0020] Compared with the prior art, the present invention has the following advantages:

[0021] 1) This invention is based on supercritical water gasification technology, which avoids the generation of nitrogen and sulfur pollutants. The high-concentration carbon dioxide after cooling and separation is partially recycled back to the burner to control the turbine inlet temperature, and complete carbon capture of carbon dioxide in the system, which can realize efficient, clean and low-carbon power generation from coal.

[0022] 2) This invention couples a supercritical carbon dioxide power generation cycle to the heat flow end of a coal supercritical water gasification power generation system, thereby fully recovering the waste heat from the gasification syngas and turbine exhaust gas, and achieving efficient matching of system waste heat.

[0023] 3) This invention effectively reduces the heat exchange temperature difference and irreversible heat transfer loss at the hot and cold ends of the heat exchanger by rationally separating the gasified syngas and supercritical carbon dioxide working fluid in the system, thereby improving the power generation efficiency of the system. Attached Figure Description

[0024] Figure 1 This is a schematic diagram of the coal supercritical water gasification power generation system coupled with a supercritical carbon dioxide cycle according to the present invention.

[0025] Figure 1 In the middle section: 1 is the feed water pump, 2 is the low-temperature preheater, 3 is the medium-temperature preheater, 4 is the high-temperature preheater, 5 is the supercritical water gasification furnace, 6 is the No. 1 heater, 7 is the No. 1 gas-liquid separator, 8 is the burner, 9 is the gas turbine, 10 is the regenerator, 11 is the No. 2 heater, 12 is the exhaust cooler, 13 is the No. 2 gas-liquid separator, 14 is the precooler, 15 is the compressor, 16 is the low-temperature regenerator, and 17 is the high-pressure turbine. Detailed Implementation

[0026] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0027] like Figure 1 As shown, the coal supercritical water gasification power generation system coupled with supercritical carbon dioxide cycle of the present invention includes a supercritical water gasification unit, a power generation unit and a cooling carbon capture unit.

[0028] The supercritical water gasification unit includes a feedwater pump 1, a low-temperature preheater 2, a medium-temperature preheater 3, a high-temperature preheater 4, a supercritical water gasifier 5, a first heater 6, and a first gas-liquid separator 7. The gasification feedwater passes through the feedwater pump 1, sequentially through the cold ends of the low-temperature preheater 2, the medium-temperature preheater 3, and the high-temperature preheater 4, and then connects to the inlet of the supercritical water gasifier 5. Coal and oxygen are connected to the inlet of the supercritical water gasifier 5. Ash is discharged from the supercritical water gasifier 5. Syngas exits the supercritical water gasifier 5 and sequentially passes through the hot ends of the high-temperature preheater 4, the medium-temperature preheater 3, and the low-temperature preheater 2. Part of the syngas from the hot end outlet of the high-temperature preheater 4 enters the hot end inlet of the first heater 6. The hot end outlet of the first heater 6 mixes with the hot end outlet of the medium-temperature preheater 3 and enters the hot end inlet of the low-temperature preheater 2. The hot end outlet of the low-temperature preheater 2 is connected to the inlet of the first gas-liquid separator 7.

[0029] The power generation unit includes a burner 8, a gas turbine 9, a regenerator 10, a second heater 11, a precooler 14, a compressor 15, a low-temperature regenerator 16, and a high-pressure turbine 17. Oxygen and the syngas from the outlet of the first gas-liquid separator 7 are connected to the inlet of the burner 8. Part of the carbon dioxide separated by the system passes through the cold end of the regenerator 10 and then connects to the inlet of the burner 8. The product from the outlet of the burner 8 is connected to the gas turbine 9 to generate electricity, and then passes through the hot end of the regenerator 10 and the second heater 11 in sequence. In the integrated supercritical carbon dioxide power generation cycle, the carbon dioxide working fluid from the outlet of the precooler 14 is split into two paths after passing through the compressor 15: the first path is connected to the cold end of the low-temperature regenerator 16 and the first heater 6 in sequence, and the second path is connected to the cold end of the second heater 11. Finally, the two carbon dioxide working fluids are connected to the high-pressure turbine 17 to generate electricity, and then pass through the hot end of the low-temperature regenerator 16 and enter the precooler 14, completing a closed supercritical carbon dioxide power generation cycle.

[0030] The cooling carbon capture unit includes an exhaust cooler 12 and a second gas-liquid separator 13; the hot end outlet of the second heater 11 is connected to the inlet of the second gas-liquid separator 13 through the exhaust cooler 12 to separate carbon dioxide in the gas phase and water in the liquid phase; part of the carbon dioxide at the gas phase outlet of the second gas-liquid separator 13 is recycled back into the system through the burner 8, and the remaining carbon dioxide is completely captured.

[0031] Preferably, the supercritical water gasifier 5 operates at a temperature of 500℃-800℃ and an operating pressure of 23MPa-32MPa, so that the supercritical water gasification reaction of coal can occur under these conditions.

[0032] Preferably, the oxygen is split into two streams. One stream of oxygen enters the supercritical water gasifier 5, where it undergoes a partial oxidation supercritical water gasification reaction with the coal and gasification feedwater. The heat released is just enough to provide the heat required for the gasification reaction, achieving the self-heating balance of the system. The other stream of oxygen enters the burner 8, where it undergoes a complete oxidation reaction with the syngas. The main components of the product at the outlet of the burner 8 are carbon dioxide and water.

[0033] Preferably, a portion of the carbon dioxide separated by the system cooling is preheated by the regenerator 10 and then recirculated into the burner 8 as cooling gas for the gas turbine 9. By changing the flow rate of the recirculated carbon dioxide working fluid, the inlet temperature of the gas turbine 9 can be adjusted, thus meeting different turbine inlet temperature requirements and improving the flexibility of unit operation.

[0034] Preferably, the inlet temperature of the gas turbine 9 is 1000℃-1600℃ and the inlet pressure is 1.5MPa-3MPa, which gives the gas turbine 9 high inlet parameters.

[0035] Preferably, the exhaust pressure of the high-pressure turbine 17 is 7.6MPa-8.5MPa, so that while maintaining the high output power of the high-pressure turbine 17, the carbon dioxide working fluid is kept in a supercritical state throughout the entire supercritical carbon dioxide power generation cycle.

[0036] Preferably, the temperature of the working fluid at the outlet of the precooler 14 is 31°C-38°C, which keeps the carbon dioxide working fluid at the outlet of the precooler 14 near the critical point, reducing the compression power consumption of the compressor 15 and thereby improving the power generation efficiency of the supercritical carbon dioxide cycle.

[0037] Preferably, the supercritical carbon dioxide working fluid at the outlet of the compressor 15 is split into two paths: the first path first enters the low-temperature regenerator 16 for preheating, and then enters the first heater 6 to recover the waste heat of the syngas; the second path enters the second heater 11 to recover the exhaust waste heat of the turbine. By reasonably splitting the working fluid at the outlet of the compressor 15, the minimum heat exchange temperature difference between the low-temperature regenerator 16, the first heater 6, and the second heater 11 is 5℃-15℃. This can reduce the heat exchange temperature difference and irreversible losses at the hot and cold ends of the heat exchanger, and improve the power generation efficiency of the system.

[0038] like Figure 1 As shown, the operation method of the coal supercritical water gasification power generation system coupled with a supercritical carbon dioxide cycle according to the present invention is as follows: Gasification feedwater, after passing through feedwater pump 1, is preheated sequentially through the cold ends of low-temperature preheater 2, medium-temperature preheater 3, and high-temperature preheater 4; the preheated gasification feedwater, coal, and oxygen enter the supercritical water gasifier 5, where a partially oxidized supercritical water gasification reaction occurs. The heat released by the partial oxidation of coal is just enough to provide the heat required for the supercritical water gasification reaction, achieving the system's self-heating balance; ash is discharged from the outlet of the supercritical water gasifier 5 through an ash discharge pipe; the syngas from the outlet of the supercritical water gasifier 5 is sequentially passed through… The gasification feedwater is preheated to approximately 400°C by passing through the hot ends of the high-temperature preheater 4, the medium-temperature preheater 3, and the low-temperature preheater 2. To ensure that the gasification feedwater is preheated to a high temperature while further recovering the waste heat of the syngas, a portion of the syngas from the hot end outlet of the high-temperature preheater 4 is diverted into the hot end inlet of the No. 1 heater 6 for partial waste heat recovery. The syngas from the hot end outlet of the No. 1 heater 6 is mixed with the syngas from the hot end outlet of the medium-temperature preheater 3 and enters the hot end inlet of the low-temperature preheater 2. The syngas from the hot end outlet of the low-temperature preheater 2 then enters the No. 1 gas-liquid separator 7 for gas-liquid separation.

[0039] Syngas and oxygen from the outlet of gas-liquid separator 7 enter burner 8. Part of the separated carbon dioxide, after preheating at the cold end of regenerator 10, enters burner 8. Complete oxidation of the syngas occurs in burner 8, yielding combustion products primarily composed of carbon dioxide and water. The outlet products of burner 8 enter gas turbine 9 to generate electricity. Turbine exhaust from gas turbine 9 enters the hot end inlet of regenerator 10 to preheat the circulating carbon dioxide working fluid. The working fluid from the hot end outlet of regenerator 10 enters the hot end inlet of heater 11 to further recover waste heat from the turbine exhaust. The working fluid from the hot end outlet of heater 11 enters exhaust cooler 12 for cooling, then enters gas-liquid separator 13 to separate gaseous carbon dioxide and liquid water. Part of the carbon dioxide from the gaseous outlet of gas-liquid separator 13, after preheating in regenerator 10, recirculates into burner 8 as cooling gas to regulate the inlet temperature of gas turbine 9. The remaining carbon dioxide can be completely captured.

[0040] To further recover waste heat from syngas and turbine exhaust, a supercritical carbon dioxide power generation cycle is coupled at the system's heat flow end. Syngas and turbine exhaust recover waste heat through supercritical carbon dioxide working fluid in heater 6 and heater 11 respectively, improving the system's power generation efficiency. The integrated supercritical carbon dioxide power generation cycle operates as follows: The carbon dioxide working fluid at the outlet of precooler 14 enters compressor 15 for pressurization; the pressurized supercritical carbon dioxide working fluid is split into two paths: the first path enters cryogenic regenerator 16 for preliminary preheating, and then enters heater 6 to recover waste heat from syngas; the second path enters heater 11 to recover waste heat from turbine exhaust. The working fluids at the outlets of heater 6 and heater 11 are mixed and enter high-pressure turbine 17 to generate electricity, achieving efficient recovery of system waste heat; the working fluid at the outlet of high-pressure turbine 17 enters the hot end inlet of cryogenic regenerator 16, and then enters precooler 14 for cooling, completing a closed supercritical carbon dioxide power generation cycle.

[0041] This invention couples a supercritical carbon dioxide power generation cycle to the heat flow end of a coal supercritical water gasification power generation system, fully recovering the waste heat from the gasification syngas and turbine exhaust gas, thus achieving efficient matching of system waste heat. By rationally separating the gasification syngas and supercritical carbon dioxide working fluid in the system, the heat exchange temperature difference between the hot and cold ends of the heat exchanger and irreversible heat transfer losses are effectively reduced, improving the system's power generation efficiency and ultimately promoting efficient, clean, and low-carbon coal power generation.

Claims

1. A coal supercritical water gasification power generation system coupled with a supercritical carbon dioxide cycle, characterized in that: The system includes a supercritical water gasification unit, a power generation unit, and a cooling carbon capture unit; The supercritical water gasification unit includes a feedwater pump (1), a low-temperature preheater (2), a medium-temperature preheater (3), a high-temperature preheater (4), a supercritical water gasifier (5), a first heater (6), and a first gas-liquid separator (7). Gasification feedwater passes through the feedwater pump (1), sequentially through the cold ends of the low-temperature preheater (2), the medium-temperature preheater (3), and the high-temperature preheater (4), and then connects to the inlet of the supercritical water gasifier (5). Coal and oxygen are connected to the inlet of the supercritical water gasifier (5). Ash is extracted from the supercritical... Water gasifier (5) discharges; syngas from the outlet of supercritical water gasifier (5) passes sequentially through the hot end of high temperature preheater (4), medium temperature preheater (3) and low temperature preheater (2). Part of the syngas from the hot end outlet of high temperature preheater (4) enters the hot end inlet of No. 1 heater (6). The hot end outlet of No. 1 heater (6) mixes with the hot end outlet of medium temperature preheater (3) and enters the hot end inlet of low temperature preheater (2). The hot end outlet of low temperature preheater (2) is connected to the inlet of No. 1 gas-liquid separator (7). The power generation unit includes a burner (8), a gas turbine (9), a regenerator (10), a second heater (11), a precooler (14), a compressor (15), a low-temperature regenerator (16), and a high-pressure turbine (17); oxygen and the syngas from the outlet of the first gas-liquid separator (7) are connected to the inlet of the burner (8); part of the carbon dioxide separated by the system passes through the cold end of the regenerator (10) and is then connected to the inlet of the burner (8); the outlet product of the burner (8) is connected to the gas turbine (9) to generate electricity, and then passes through the regenerator (10) and the gas turbine (17) in sequence. The hot end of the second heater (11); In the integrated supercritical carbon dioxide power generation cycle, the carbon dioxide working fluid at the outlet of the precooler (14) is split into two paths after passing through the compressor (15): the first path is connected to the cold end of the low temperature regenerator (16) and the first heater (6) in sequence, the second path is connected to the cold end of the second heater (11), and finally the two paths of carbon dioxide working fluid are connected to the high pressure turbine (17) to do work and generate electricity, and then enter the precooler (14) after passing through the hot end of the low temperature regenerator (16) to complete a closed supercritical carbon dioxide power generation cycle. The cooling carbon capture unit includes an exhaust cooler (12) and a second gas-liquid separator (13); the hot end outlet of the second heater (11) is connected to the inlet of the second gas-liquid separator (13) through the exhaust cooler (12) to separate carbon dioxide in the gas phase and water in the liquid phase; part of the carbon dioxide at the gas phase outlet of the second gas-liquid separator (13) is recycled back into the system through the burner (8), and the remaining carbon dioxide is completely captured. Oxygen is split into two streams. One stream of oxygen enters the supercritical water gasifier (5) and undergoes a supercritical water gasification reaction with coal and gasification feedwater, releasing heat that provides the heat required for the gasification reaction. The other stream of oxygen enters the burner (8) and undergoes a complete oxidation reaction with the syngas. The main components of the product at the outlet of the burner (8) are carbon dioxide and water. After the system is cooled and separated, part of the carbon dioxide is preheated by the regenerator (10) and then recirculated into the burner (8) as the cooling gas of the gas turbine (9). By changing the flow rate of the recirculated carbon dioxide working fluid, the inlet temperature of the gas turbine (9) can be adjusted.

2. The coal supercritical water gasification power generation system coupled with a supercritical carbon dioxide cycle according to claim 1, characterized in that: The supercritical water gasifier (5) operates at a temperature of 500℃ – 800℃ and a pressure of 23 MPa – 32 MPa.

3. The coal supercritical water gasification power generation system coupled with a supercritical carbon dioxide cycle according to claim 1, characterized in that: The inlet temperature of the gas turbine (9) is 1000℃ – 1600℃, and the inlet pressure is 1.5 MPa – 3MPa.

4. The coal supercritical water gasification power generation system coupled with a supercritical carbon dioxide cycle according to claim 1, characterized in that: The exhaust pressure of the high-pressure turbine (17) is 7.6 MPa – 8.5 MPa.

5. The coal supercritical water gasification power generation system coupled with a supercritical carbon dioxide cycle according to claim 1, characterized in that: The temperature of the working fluid at the outlet of the precooler (14) is 31℃ – 38℃.

6. The coal supercritical water gasification power generation system coupled with a supercritical carbon dioxide cycle according to claim 1, characterized in that: The supercritical carbon dioxide working fluid at the outlet of the compressor (15) is split into two paths: the first path first enters the low-temperature regenerator (16) for preheating, and then enters the first heater (6) to recover the waste heat of the synthesis gas; the second path enters the second heater (11) to recover the exhaust waste heat of the turbine; through the reasonable splitting of the working fluid at the outlet of the compressor (15), the minimum heat exchange temperature difference between the low-temperature regenerator (16), the first heater (6) and the second heater (11) is 5℃ – 15℃.

7. The operation method of the coal supercritical water gasification power generation system coupled with a supercritical carbon dioxide cycle as described in any one of claims 1 to 6, characterized in that: After passing through the feedwater pump (1), the gasification feedwater is preheated sequentially through the cold ends of the low-temperature preheater (2), the medium-temperature preheater (3), and the high-temperature preheater (4). The preheated gasification feedwater, coal, and oxygen enter the supercritical water gasifier (5) and undergo a partially oxidized supercritical water gasification reaction. Ash is discharged from the outlet of the supercritical water gasifier (5) through the ash discharge pipe. The syngas from the outlet of the supercritical water gasifier (5) passes sequentially through the hot ends of the high-temperature preheater (4), the medium-temperature preheater (3), and the low-temperature preheater (2) to preheat the gasification feedwater. Part of the syngas from the hot end outlet of the high-temperature preheater (4) enters the hot end inlet of the No. 1 heater (6). The syngas from the hot end outlet of the No. 1 heater (6) mixes with the syngas from the hot end outlet of the medium-temperature preheater (3) and enters the hot end inlet of the low-temperature preheater (2). The syngas from the hot end outlet of the low-temperature preheater (2) enters the No. 1 gas-liquid separator (7) for gas-liquid separation. Oxygen and... The syngas from the outlet of the No. 7 gas-liquid separator enters the burner (8). After separation, part of the carbon dioxide is preheated at the cold end of the regenerator (10) and then enters the burner (8). The product from the outlet of the burner (8) enters the gas turbine (9) to generate electricity. The exhaust gas from the outlet of the gas turbine (9) enters the hot end inlet of the regenerator (10) to preheat the circulating carbon dioxide working fluid. The working fluid from the hot end outlet of the regenerator (10) enters the hot end inlet of the second heater (11) to further recover the waste heat from the turbine exhaust. The working fluid from the hot end outlet of the second heater (11) enters the exhaust cooler (12) for cooling and then enters the No. 2 gas-liquid separator (13) to separate carbon dioxide in the gas phase and water in the liquid phase. Part of the carbon dioxide from the gas phase outlet of the No. 2 gas-liquid separator (13) is preheated at the regenerator (10) and then circulated back into the burner (8), achieving complete carbon capture of the remaining carbon dioxide. In the integrated supercritical carbon dioxide power generation cycle, the carbon dioxide working fluid at the outlet of the precooler (14) enters the compressor (15) for pressurization; the pressurized supercritical carbon dioxide working fluid is split into two paths: the first path first enters the low-temperature regenerator (16) for preheating, and then enters the No. 1 heater (6) to recover the waste heat of the synthesis gas; the second path enters the No. 2 heater (11) to recover the waste heat of the turbine exhaust gas. The working fluids at the outlets of the No. 1 heater (6) and the No. 2 heater (11) are mixed and enter the high-pressure turbine (17) to generate electricity; the working fluid at the outlet of the high-pressure turbine (17) enters the hot end inlet of the low-temperature regenerator (16), and then enters the precooler (14) for cooling, completing a closed loop.

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