System and method for circulating power plant compressor intake and low pressure cylinder exhaust

Abstract

This invention discloses a system and method for compressor intake and low-pressure cylinder exhaust in a combined cycle power plant, relating to the field of energy conservation, consumption reduction, and comprehensive utilization technology in gas turbine combined cycle power plants. It includes a gas turbine intake cooling section and a low-pressure cylinder exhaust cooling section. The gas turbine intake cooling section includes a liquefied natural gas (LNG) storage tank. The bottom outlet of the LNG storage tank is connected to an LNG booster pump and an LNG booster pump outlet flow control valve via a cryogenic pipeline. The pressurized LNG enters the natural gas side of the LNG-ethylene glycol aqueous solution heat exchanger. This invention fully utilizes the cold energy released during the gasification process of LNG to reduce the inlet air temperature of the gas turbine compressor, increasing air density and power generation. Simultaneously, it utilizes the cold energy released during LNG gasification to reduce the exhaust temperature of the turbine's low-pressure cylinder, lowering the condenser pressure and allowing the steam to fully expand and perform work within the low-pressure cylinder, thereby improving power generation and unit efficiency.

Description

Technical Field

[0001] This invention relates to the field of energy conservation, consumption reduction and comprehensive utilization technology in gas-fired combined cycle power plants, specifically to a system and method for compressor intake and low-pressure cylinder exhaust in a combined cycle power plant. Background Technology

[0002] Gas-fired combined cycle (COC) power plants, with their advantages of small size, fast start-up, and high thermal efficiency, are considered ideal for peak-shaving. However, during peak electricity consumption periods in summer, high ambient temperatures cause a decrease in unit output, significantly weakening peak-shaving capabilities. Studies show that a 1°C increase in ambient temperature can reduce the rated power generation capacity of a gas turbine by up to 1%. The decrease in gas turbine output with rising ambient temperature is primarily due to the fact that gas turbines are constant-volume-flow power devices; the mass of the air flowing through them depends on air density. Higher temperatures result in lower density, reducing the mass flow rate of air into the compressor and consequently decreasing the unit's work capacity. Furthermore, the compressor's power consumption is directly proportional to the thermodynamic temperature of the intake air; that is, as ambient temperature rises, compressor power consumption increases, leading to a decrease in the gas turbine's net output. Simultaneously, the increased ambient temperature leads to higher circulating water supply temperature, increasing the exhaust back pressure of the turbine's low-pressure cylinder and reducing its work capacity. These power losses at both the gas turbine inlet and exhaust ends significantly reduce the overall output of the COC power plant.

[0003] Because gas-fired combined cycle power plants are highly sensitive to upstream natural gas prices and downstream grid-connected electricity prices, related power generation companies have a strong demand for cost reduction, efficiency improvement, energy conservation, and consumption reduction, which puts forward new requirements for the optimization of related thermal systems. Summary of the Invention

[0004] This invention provides a system and method for compressor intake and low-pressure cylinder exhaust in a circulating power plant to solve the problems mentioned in the background art.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0006] A system and method for compressor intake and low-pressure cylinder exhaust in a circulating power plant includes a gas turbine intake cooling section and a low-pressure cylinder exhaust cooling section. The gas turbine intake cooling section includes a liquefied natural gas (LNG) storage tank. The bottom outlet of the LNG storage tank is connected to an LNG booster pump and an LNG booster pump outlet flow control valve via a cryogenic pipeline. The pressurized LNG enters the natural gas side of an LNG-ethylene glycol aqueous solution heat exchanger. Through this heat exchanger, the LNG transfers its cold energy to the ethylene glycol aqueous solution. Simultaneously, the LNG absorbs the heat transferred from the ethylene glycol aqueous solution and changes from a liquid state to a gas state before entering the gas turbine combustion chamber for combustion and power generation. The ethylene glycol solution on the ethylene glycol side of the liquefied natural gas-ethylene glycol aqueous solution heat exchanger absorbs the cold energy released by the liquefied natural gas, and its temperature can drop to near zero degrees Celsius. The low-temperature ethylene glycol aqueous solution enters the ethylene glycol side of the ethylene glycol aqueous solution-air heat exchanger installed in the gas turbine intake unit through the ethylene glycol aqueous solution circulation pump and the ethylene glycol aqueous solution circulation pump outlet flow control valve. After the gas turbine intake air passes through the air side of the heat exchanger, its temperature decreases and its mass flow rate increases, thereby improving the gas turbine's power generation capacity. During the heat exchange process, the condensate generated by the temperature drop on the air side of the ethylene glycol aqueous solution-air heat exchanger is discharged to the outside of the intake unit through the drain pipe along the heat exchange fins.

[0007] The low-pressure cylinder exhaust cooling section includes a liquefied natural gas (LNG) storage tank. The bottom outlet of the LNG storage tank is connected via a cryogenic pipeline to an LNG booster pump and an LNG booster pump outlet flow control valve. The pressurized LNG enters the LNG-condensate heat exchanger on the natural gas side. Through this heat exchanger, the LNG transfers its cooling energy to the condensate, and simultaneously absorbs the heat transferred from the condensate, changing from a liquid to a gaseous state before entering the gas turbine combustion chamber for combustion and power generation. The condenser hot well outlet is connected to the condensate... The condensate pump and condensate cooling circulation pump are used to pump condensate. Most of the condensate is pressurized by the condensate pump and then enters the low-pressure steam drum of the waste heat boiler. The other part of the condensate passes through the condensate cooling circulation pump and the condensate cooling circulation pump outlet flow control valve and enters the condensate side of the liquefied natural gas-condensate heat exchanger. After heat exchange, the condensate with a lower temperature enters the low-temperature condensate spray device arranged at the throat of the condenser. The low-temperature condensate sprayed by the low-temperature condensate spray device is fully mixed and heat exchanged with the exhaust steam of the low-pressure cylinder. The condensate enters the condenser hot well and is ready for the next cycle.

[0008] A further improvement of the technical solution of the present invention is that the liquefied natural gas storage tank is connected to liquefied natural gas booster pump one and liquefied natural gas booster pump two respectively through liquefied natural gas cryogenic transportation pipelines.

[0009] A further improvement of the technical solution of the present invention is that: after the liquefied natural gas passes through the liquefied natural gas-ethylene glycol aqueous solution heat exchanger and is heated to room temperature, it is mixed with the natural gas that has passed through the liquefied natural gas-condensate heat exchanger and been heated to room temperature. The mixed natural gas then enters the combustion chamber of the gas turbine for combustion and work.

[0010] A further improvement of the technical solution of the present invention is that: the ethylene glycol aqueous solution-air heat exchanger is arranged in the gas turbine intake device, and the heat exchange element adopts a finned tube bundle with low resistance and high heat transfer coefficient, arranged in layers, with each layer having a condensate drainage pipe.

[0011] A further improvement of the technical solution of the present invention is that: the low-temperature condensate spraying device is arranged in the throat of the condenser, including components such as spray pipe bundle, nozzle and baffle plate. After the condensate is sprayed out from the nozzle, it forms a vertical fan-shaped water film, sprays onto the baffle plate, and fully exchanges heat with the exhaust steam of the low-pressure cylinder to form condensate before returning to the hot well.

[0012] The operating method for the compressor intake and low-pressure cylinder exhaust of a circulating power plant includes the following steps:

[0013] Step 1: Compressor Inlet Cooling Section

[0014] A1. Inspect the integrity of the ethylene glycol side of the liquefied natural gas-ethylene glycol aqueous solution heat exchanger, the ethylene glycol aqueous solution circulation pump, the outlet flow control valve of the ethylene glycol aqueous solution circulation pump, and the ethylene glycol side circuit of the ethylene glycol aqueous solution-air heat exchanger. The system pressure is between 0.3 and 0.5 MPa, the concentration of ethylene glycol aqueous solution in the system is around 50%, and there are no leaks or defects in the system.

[0015] A2. Start the ethylene glycol aqueous solution circulation pump, and maintain the outlet pressure of the circulation pump at about 0.8MPa by controlling the outlet flow control valve of the ethylene glycol aqueous solution circulation pump to establish an ethylene glycol aqueous solution circulation loop;

[0016] A3. After the gas turbine is ignited, connected to the grid, and under load, check that the pressure, temperature, and level of the liquefied natural gas (LNG) storage tank are normal. Start the LNG booster pump one. By controlling the LNG booster pump outlet flow control valve one, ensure that the inlet temperature of the ethylene glycol aqueous solution circulation pump is not lower than 4°C. This prevents the ethylene glycol aqueous solution below zero degrees Celsius from entering the ethylene glycol aqueous solution-air heat exchanger, which would cause the air-side condensate to freeze, reducing the heat transfer coefficient and affecting the heat exchange effect. As the gas turbine load increases, simultaneously increase the opening of the ethylene glycol aqueous solution circulation pump outlet flow control valve and the LNG booster pump outlet flow control valve one to maintain a stable gas turbine inlet temperature and a stable natural gas outlet temperature on the natural gas side of the LNG-ethylene glycol aqueous solution heat exchanger.

[0017] A4. When a gas-fired combined cycle power plant is reducing its load or preparing to shut down, the natural gas outlet flow rate on the natural gas side of the liquefied natural gas-ethylene glycol aqueous solution heat exchanger should be reduced first. The gas volume missing in the combustion chamber should be supplemented by conventional natural gas to maintain stable gas turbine output. As the load decreases, the flow rate of the ethylene glycol aqueous solution should be controlled by reducing the opening of the outlet flow control valve of the ethylene glycol aqueous solution circulation pump. During the adjustment process, care should be taken to maintain the solution temperature at no less than 4°C.

[0018] Step 2: Low-pressure cylinder exhaust cooling section:

[0019] B1. Inspect the integrity of the condensate side of the liquefied natural gas-condensate heat exchanger, the condensate cooling circulation pump, the condensate cooling circulation pump outlet flow control valve, and the low-temperature condensate spray device circuit. The system has no leaks or defects.

[0020] B2. Start the condensate cooling circulation pump and maintain the outlet pressure of the circulation pump at about 1.0MPa by controlling the outlet flow control valve of the condensate cooling circulation pump to establish a condensate circulation loop.

[0021] B3. After the turbine is connected to the grid and under load, check that the pressure, temperature, and liquid level of the liquefied natural gas (LNG) storage tank are normal. Start the LNG booster pump II and control the opening of the LNG booster pump outlet flow control valve II to ensure that the condensate side outlet temperature of the LNG-condensate heat exchanger is not lower than 4°C to prevent freezing from affecting the normal operation of the low-temperature condensate spray device. As the turbine load increases, simultaneously increase the opening of the condensate cooling circulation pump outlet flow control valve and the LNG booster pump outlet flow control valve II to maintain the low-temperature condensate temperature and the natural gas side outlet temperature of the LNG-condensate heat exchanger.

[0022] B4. When the turbine is being reduced in load or is about to be shut down, the flow rate on the natural gas side of the liquefied natural gas-condensate heat exchanger should be reduced first. At the same time, the temperature of the low-temperature condensate should be maintained at no less than 4°C by gradually closing the outlet flow control valve of the condensate cooling circulation pump until the turbine is successfully shut down and the low-temperature condensate and liquefied natural gas operations are discontinued.

[0023] Due to the adoption of the above technical solution, the technical progress achieved by this invention compared to the prior art is as follows:

[0024] 1. This invention provides a system and method for compressor intake and low-pressure cylinder exhaust in a combined cycle power plant. By fully utilizing the cold energy released during the gasification process of liquefied natural gas, it is used for gas turbine intake cooling and steam turbine exhaust cooling in a combined cycle power plant, thereby improving the combined cycle power generation and thermal efficiency, reducing power plant operating costs, and enhancing the degree of energy cascade utilization.

[0025] This invention provides a system and method for compressor intake and low-pressure cylinder exhaust in a circulating power plant. During system operation, the flow rates of the working fluids on both sides of the liquefied natural gas-ethylene glycol aqueous solution heat exchanger and the liquefied natural gas-condensate heat exchanger can be adjusted in a timely manner according to changes in unit load to regulate the gas turbine intake temperature and low-pressure cylinder exhaust temperature, thereby adapting to different operating requirements.

[0026] This invention provides a system and method for compressor intake and low-pressure cylinder exhaust in a circulating power plant. The system operation mode enables efficient utilization of the cold energy released during the gasification process of liquefied natural gas, improves the overall efficiency and economy of the combined gas and steam power plant, and helps power companies gain a favorable position in future energy market competition, thereby enhancing their competitiveness.

[0027] This invention provides a system and method for compressor intake and low-pressure cylinder exhaust in a combined cycle power plant, which uses liquefied natural gas as fuel and has the potential for widespread application. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of the thermal system of the present invention.

[0029] In the diagram: 1. Liquefied natural gas (LNG) storage tank; 2. LNG booster pump one; 3. LNG booster pump outlet flow control valve one; 4. LNG-ethylene glycol aqueous solution heat exchanger; 5. Ethylene glycol aqueous solution circulating pump; 6. Ethylene glycol aqueous solution circulating pump outlet flow control valve; 7. Ethylene glycol aqueous solution-air heat exchanger; 8. LNG booster pump two; 9. LNG booster pump outlet flow control valve two; 10. Condensate cooling circulating pump; 11. Condensate cooling circulating pump outlet flow control valve; 12. LNG-condensate heat exchanger; 13. Low-temperature condensate spray device; 14. Condensate pump. Detailed Implementation

[0030] The present invention will now be described in further detail with reference to the accompanying drawings.

[0031] See Figure 1This invention provides a system for the intake air of a gas turbine compressor and the exhaust air of a low-pressure cylinder in a circulating power plant, including a gas turbine intake cooling section and a low-pressure cylinder exhaust cooling section. The gas turbine intake cooling section includes a liquefied natural gas (LNG) storage tank 1. The bottom outlet of the LNG storage tank 1 is connected to an LNG booster pump 2 and an LNG booster pump outlet flow control valve 3 via a cryogenic pipeline. The pressurized LNG enters the LNG-ethylene glycol aqueous solution heat exchanger 4 on the natural gas side. Through this heat exchanger, the LNG transfers its cold energy to the ethylene glycol aqueous solution. At the same time, the LNG absorbs the heat transferred by the ethylene glycol aqueous solution and changes from a liquid state to a gas state before entering the gas turbine combustion chamber to burn and perform work. The ethylene glycol solution on the ethylene glycol side of the liquefied natural gas-ethylene glycol aqueous solution heat exchanger 4 absorbs the cold energy released by the liquefied natural gas, and its temperature can be reduced to near zero degrees Celsius. The low-temperature ethylene glycol aqueous solution enters the ethylene glycol aqueous solution-air heat exchanger 7 installed in the gas turbine intake device through the ethylene glycol aqueous solution circulation pump 5 and the ethylene glycol aqueous solution circulation pump outlet flow control valve 6. After the gas turbine intake air passes through the air side of the heat exchanger, its temperature decreases and its mass flow rate increases, thereby improving the gas turbine's power generation capacity. During the heat exchange process, the condensate generated by the temperature drop on the air side of the ethylene glycol aqueous solution-air heat exchanger 7 is discharged to the outside of the intake device through the drain pipe along the heat exchange fins.

[0032] The low-pressure cylinder exhaust cooling section includes a liquefied natural gas (LNG) storage tank 1. The bottom outlet of LNG storage tank 1 is connected via a cryogenic pipeline to an LNG booster pump 8 and an LNG booster pump outlet flow control valve 9. The pressurized LNG enters the LNG-condensate heat exchanger 12 on the natural gas side. Through this heat exchanger, the LNG transfers its cooling energy to the condensate, and simultaneously absorbs the heat transferred from the condensate, changing from a liquid to a gaseous state before entering the gas turbine combustion chamber for combustion and power generation. The condenser hot well outlet is connected to a condensate pump 14 and a condensate pump 15. The condensate cooling circulation pump 10 pressurizes most of the condensate before it enters the low-pressure steam drum of the waste heat boiler. The remaining condensate enters the condensate side of the liquefied natural gas-condensate heat exchanger 12 after passing through the condensate cooling circulation pump 10 and the condensate cooling circulation pump outlet flow control valve 11. After heat exchange, the condensate with a lower temperature enters the low-temperature condensate spray device 13 arranged at the throat of the condenser. The low-temperature condensate sprayed by the low-temperature condensate spray device 13 mixes and exchanges heat fully with the exhaust steam from the low-pressure cylinder. The condensate enters the condenser hot well and is ready for the next cycle.

[0033] The liquefied natural gas storage tank 1 is connected to the liquefied natural gas booster pump 1 2 and the liquefied natural gas booster pump 2 8 via cryogenic liquefied natural gas pipelines.

[0034] After the liquefied natural gas passes through the liquefied natural gas-ethylene glycol aqueous solution heat exchanger 4 and is heated to room temperature, it mixes with the natural gas that has passed through the liquefied natural gas-condensate heat exchanger 12 and is heated to room temperature. The mixed natural gas then enters the combustion chamber of the gas turbine to burn and perform work.

[0035] The ethylene glycol aqueous solution-air heat exchanger 7 is arranged inside the gas turbine intake device. The heat exchange elements adopt low-resistance, high-heat-transfer-coefficient finned tube bundles, arranged in layers, with each layer having condensate drainage pipes.

[0036] The low-temperature condensate spraying device 13 is arranged at the throat of the condenser and includes components such as spray pipe bundle, nozzle and baffle plate. After the condensate is sprayed out from the nozzle, it forms a vertical fan-shaped water film, which is sprayed onto the baffle plate. After fully exchanging heat with the exhaust steam of the low-pressure cylinder to form condensate, it returns to the hot well.

[0037] The following section will explain in detail the working principle of the compressor intake and low-pressure cylinder exhaust system and method of this circulating power plant.

[0038] like Figure 1 As shown, during compressor intake cooling: check the integrity of the ethylene glycol side of the LNG-ethylene glycol aqueous solution heat exchanger 4, the ethylene glycol aqueous solution circulation pump 5, the ethylene glycol aqueous solution circulation pump outlet flow control valve 6, and the ethylene glycol side loop of the ethylene glycol aqueous solution-air heat exchanger 7. The system pressure should be between 0.3 and 0.5 MPa, the system ethylene glycol aqueous solution concentration should be around 50%, and the system should be free of leaks and defects. Start the ethylene glycol aqueous solution circulation pump 5 and maintain the circulation pump outlet pressure at around 0.8 MPa by controlling the ethylene glycol aqueous solution circulation pump outlet flow control valve 6 to establish the ethylene glycol aqueous solution circulation loop. After the gas turbine is ignited, connected to the grid, and under load, check that the pressure, temperature, and liquid level of the LNG storage tank 1 are normal. Start the LNG booster pump 2 and ensure that the inlet temperature of the ethylene glycol aqueous solution circulation pump 5 is not lower than 4℃ by controlling the LNG booster pump outlet flow control valve 3. To prevent sub-zero ethylene glycol aqueous solution from entering the ethylene glycol aqueous solution-air heat exchanger 7, which could cause condensate on the air side to freeze, reducing the heat transfer coefficient and affecting the heat exchange effect; as the gas turbine load increases, the opening of the ethylene glycol aqueous solution circulation pump outlet flow control valve 6 and the liquefied natural gas booster pump outlet flow control valve -3 should be increased simultaneously to maintain stable gas turbine inlet temperature and natural gas outlet temperature on the natural gas side of the liquefied natural gas-ethylene glycol aqueous solution heat exchanger 4; when the gas-fired steam combined cycle power plant reduces load or prepares to shut down, the natural gas outlet flow rate on the natural gas side of the liquefied natural gas-ethylene glycol aqueous solution heat exchanger 4 should be reduced first, and the missing gas in the combustion chamber should be supplemented by conventional natural gas to maintain stable gas turbine output; as the load decreases, the ethylene glycol aqueous solution flow rate should be controlled by reducing the opening of the ethylene glycol aqueous solution circulation pump outlet flow control valve 6, and care should be taken to maintain the solution temperature not lower than 4°C during the adjustment process;

[0039] During low-pressure cylinder exhaust cooling: Check the integrity of the circuits of the condensate side of the LNG-condensate heat exchanger 12, the condensate cooling circulation pump 10, the condensate cooling circulation pump outlet flow control valve 11, and the low-temperature condensate spray device 13, ensuring the system is leak-free and defect-free; start the condensate cooling circulation pump 10, and maintain the circulation pump outlet pressure at approximately 1.0 MPa by controlling the condensate cooling circulation pump outlet flow control valve 11 to establish the condensate circulation loop; after the turbine is connected to the grid and under load, check that the pressure, temperature, and liquid level of the LNG storage tank 1 are normal, start the LNG booster pump 8, and ensure the LNG-condensate heat exchange is maintained by controlling the opening of the LNG booster pump outlet flow control valve 9. The condensate outlet temperature of heat exchanger 12 should not be lower than 4℃ to prevent freezing from affecting the normal operation of the low-temperature condensate spray device 13. As the turbine load increases, the opening of the condensate cooling circulation pump outlet flow control valve 11 and the liquefied natural gas booster pump outlet flow control valve 9 should be increased simultaneously to maintain the low-temperature condensate temperature and the natural gas side outlet temperature of the liquefied natural gas-condensate heat exchanger 12. When the turbine load is reduced or the turbine is prepared to shut down, the natural gas side flow of the liquefied natural gas-condensate heat exchanger 12 should be reduced first, and the low-temperature condensate temperature should be maintained at no lower than 4℃ by gradually closing the condensate cooling circulation pump outlet flow control valve 11 until the turbine is successfully shut down and the low-temperature condensate and liquefied natural gas operations are discontinued.

[0040] The present invention has been described in detail above. However, modifications or improvements can be made to it, which will be obvious to those skilled in the art. Therefore, any modifications or improvements that do not depart from the spirit of the present invention are within the scope of protection of the present invention.

Claims

1. A system for the intake air of a gas turbine compressor and the exhaust air of a low-pressure cylinder in a circulating power plant, comprising a gas turbine intake cooling section and a low-pressure cylinder exhaust cooling section, characterized in that: The gas turbine intake cooling section includes a liquefied natural gas (LNG) storage tank (1). The bottom outlet of the LNG storage tank (1) is connected to an LNG booster pump (2) and an LNG booster pump outlet flow control valve (3) via a cryogenic pipeline. After being pressurized, the LNG enters the LNG-ethylene glycol aqueous solution heat exchanger (4) on the natural gas side. Through this heat exchanger, the LNG transfers its cold energy to the ethylene glycol aqueous solution. At the same time, the LNG absorbs the heat transferred by the ethylene glycol aqueous solution and changes from a liquid state to a gas state. It then enters the gas turbine combustion chamber to burn and perform work. After passing through the LNG-ethylene glycol aqueous solution heat exchanger (4), the LNG... The ethylene glycol aqueous solution on the alcohol side absorbs the cold energy released by liquefied natural gas, and its temperature decreases to no less than 4°C. The low-temperature ethylene glycol aqueous solution enters the ethylene glycol aqueous solution-air heat exchanger (7) installed in the gas turbine intake device through the ethylene glycol aqueous solution circulation pump (5) and the ethylene glycol aqueous solution circulation pump outlet flow control valve (6). After the gas turbine intake air passes through the air side of the heat exchanger, its temperature decreases and its mass flow rate increases, thereby improving the gas turbine's power generation. During the heat exchange process, the condensate generated by the condensation due to the decrease in air temperature on the air side of the ethylene glycol aqueous solution-air heat exchanger (7) is discharged to the outside of the intake device through the drain pipe along the heat exchange fins. The low-pressure cylinder exhaust cooling section includes a liquefied natural gas (LNG) storage tank (1). The bottom outlet of the LNG storage tank (1) is connected to an LNG booster pump (8) and an LNG booster pump outlet flow control valve (9) via a cryogenic pipeline. After being boosted, the LNG enters the LNG-condensate heat exchanger (12) on the natural gas side. Through this heat exchanger, the LNG transfers its cold energy to the condensate. At the same time, the LNG absorbs the heat transferred by the condensate and changes from a liquid state to a gas state, entering the gas turbine combustion chamber to burn and perform work. The condenser hot well outlet is connected to a condensate pump (14) and a gas pump (9). The condensate cooling circulation pump (10) pressurizes most of the condensate and enters the low-pressure steam drum of the waste heat boiler. The other part of the condensate enters the condensate side of the liquefied natural gas-condensate heat exchanger (12) after passing through the condensate cooling circulation pump (10) and the condensate cooling circulation pump outlet flow control valve (11). The condensate with reduced temperature after heat exchange enters the low-temperature condensate spray device (13) arranged at the throat of the condenser. The low-temperature condensate sprayed by the low-temperature condensate spray device (13) mixes and exchanges heat fully with the exhaust steam of the low-pressure cylinder. The condensate enters the condenser hot well and is ready for the next cycle.

2. The system for compressor intake and low-pressure cylinder exhaust in a circulating power plant according to claim 1, characterized in that: The liquefied natural gas storage tank (1) is connected to liquefied natural gas booster pump one (2) and liquefied natural gas booster pump two (8) through liquefied natural gas cryogenic transmission pipelines.

3. The system for compressor intake and low-pressure cylinder exhaust in a circulating power plant according to claim 1, characterized in that: After the liquefied natural gas passes through the liquefied natural gas-ethylene glycol aqueous solution heat exchanger (4) and is heated to room temperature, it is mixed with the natural gas that passes through the liquefied natural gas-condensate heat exchanger (12) and is heated to room temperature. The mixed natural gas then enters the combustion chamber of the gas turbine to burn and perform work.

4. The system for compressor intake and low-pressure cylinder exhaust in a circulating power plant according to claim 1, characterized in that: The ethylene glycol aqueous solution-air heat exchanger (7) is arranged inside the gas turbine intake device. The heat exchange elements are low-resistance, high-heat-transfer-coefficient finned tube bundles, arranged in layers, with each layer having a condensate drainage pipe.

5. The system for compressor intake and low-pressure cylinder exhaust in a circulating power plant according to claim 1, characterized in that: The low-temperature condensate spraying device (13) is arranged at the throat of the condenser and includes a spray tube bundle, a nozzle and a baffle plate component. After the condensate is sprayed out from the nozzle, it forms a vertical fan-shaped water film, which is sprayed onto the baffle plate. After fully exchanging heat with the exhaust steam of the low-pressure cylinder to form condensate, it returns to the hot well.

6. A system operation method for the compressor intake and low-pressure cylinder exhaust of a circulating power plant according to any one of claims 1-5, characterized in that, Includes the following steps: Step 1: Compressor Inlet Cooling Section A1. Check the integrity of the ethylene glycol side of the liquefied natural gas-ethylene glycol aqueous solution heat exchanger (4), the ethylene glycol aqueous solution circulation pump (5), the outlet flow control valve of the ethylene glycol aqueous solution circulation pump (6), and the ethylene glycol side circuit of the ethylene glycol aqueous solution-air heat exchanger (7). The system pressure is between 0.3 and 0.5 MPa, the concentration of ethylene glycol aqueous solution in the system is around 50%, and there are no leaks or defects in the system. A2. Start the ethylene glycol aqueous solution circulation pump (5), and maintain the outlet pressure of the circulation pump at about 0.8MPa by controlling the outlet flow control valve (6) of the ethylene glycol aqueous solution circulation pump to establish an ethylene glycol aqueous solution circulation loop; A3. After the gas turbine is ignited and connected to the grid under load, check that the pressure, temperature and liquid level of the liquefied natural gas storage tank (1) are normal. Start the liquefied natural gas booster pump (2). By controlling the outlet flow control valve (3) of the liquefied natural gas booster pump, ensure that the inlet temperature of the ethylene glycol aqueous solution circulation pump (5) is not lower than 4°C. Avoid the low temperature ethylene glycol aqueous solution below zero degrees entering the ethylene glycol aqueous solution-air heat exchanger (7) and causing the air side condensate to freeze, reducing the heat transfer coefficient and affecting the heat exchange effect. As the gas turbine load increases, simultaneously increase the opening of the outlet flow control valve (6) of the ethylene glycol aqueous solution circulation pump and the outlet flow control valve (3) of the liquefied natural gas booster pump to maintain the gas turbine inlet temperature and the natural gas outlet temperature on the natural gas side of the liquefied natural gas-ethylene glycol aqueous solution heat exchanger (4). A4. When the gas-steam combined cycle power plant is reducing load or preparing to shut down, the natural gas outlet flow rate of the liquefied natural gas-ethylene glycol aqueous solution heat exchanger (4) on the natural gas side should be reduced first. The gas volume missing in the combustion chamber should be supplemented by conventional natural gas to maintain the stable output of the gas turbine. As the load decreases, the flow rate of the ethylene glycol aqueous solution should be controlled by reducing the opening of the ethylene glycol aqueous solution circulation pump outlet flow control valve (6). During the adjustment process, attention should be paid to maintaining the solution temperature not lower than 4℃. Step 2: Low-pressure cylinder exhaust cooling section: B1. Check the integrity of the circuits of the condensate side of the liquefied natural gas-condensate heat exchanger (12), the condensate cooling circulation pump (10), the condensate cooling circulation pump outlet flow control valve (11), and the low-temperature condensate spray device (13). The system has no leaks or defects. B2. Start the condensate cooling circulation pump (10), and maintain the outlet pressure of the circulation pump at about 1.0MPa by controlling the outlet flow control valve (11) of the condensate cooling circulation pump to establish a condensate circulation loop; B3. After the turbine is connected to the grid and under load, check that the pressure, temperature and liquid level of the liquefied natural gas storage tank (1) are normal, start the liquefied natural gas booster pump (8), and ensure that the outlet temperature of the condensate side of the liquefied natural gas-condensate heat exchanger (12) is not lower than 4°C by controlling the opening of the outlet flow control valve (9) of the liquefied natural gas booster pump. Avoid freezing and affecting the normal operation of the low-temperature condensate spray device (13). As the turbine load increases, simultaneously increase the opening of the outlet flow control valve (11) of the condensate cooling circulation pump and the outlet flow control valve (9) of the liquefied natural gas booster pump to maintain the low-temperature condensate temperature and the natural gas side outlet temperature of the liquefied natural gas-condensate heat exchanger (12). B4. When the turbine is reduced in load or is about to be shut down, the flow rate of the natural gas side of the liquefied natural gas-condensate heat exchanger (12) should be reduced first. At the same time, the temperature of the low-temperature condensate should be maintained at no less than 4°C by gradually closing the outlet flow control valve (11) of the condensate cooling circulation pump until the turbine is successfully shut down and the low-temperature condensate and liquefied natural gas operation is stopped.

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