Power generation system based on supercritical carbon dioxide brayton cycle

Abstract

The present application discloses a power generation system based on a supercritical carbon dioxide Brayton cycle. The power generation system comprises: a main cycle system, comprising an integrated component, a heating path, and a cooling path, wherein the integrated component is connected between the heating path and the cooling path, so as to form an overall loop of the Brayton cycle; and an auxiliary cycle system, comprising a leakage flow path and a heat pump cycle loop, wherein the leakage flow path is connected between a bleed port of the integrated component and the main cycle system, the heat pump cycle loop is connected to the overall loop of the main cycle system by means of a drainage path, and the leakage flow path exchanges heat with the heat pump cycle loop by means of a heat exchange assembly.

Description

Power generation system based on supercritical carbon dioxide Brayton cycle

[0001] Cross-reference to related applications

[0002] This application claims priority to Chinese patent application 202411426992.4, filed on October 12, 2024, entitled “Power Generation System Based on Supercritical Carbon Dioxide Brayton Cycle”, the entire contents of which are incorporated herein by reference. Technical Field

[0003] This application belongs to the field of thermal power generation technology, and in particular relates to a power generation system based on supercritical carbon dioxide Brayton cycle. Background Technology

[0004] In the field of thermal power generation, supercritical carbon dioxide Brayton cycles are typically used to convert thermal energy into electrical energy. A supercritical carbon dioxide Brayton cycle uses high-temperature, high-pressure supercritical carbon dioxide to drive a turbine, which in turn drives a motor to generate electricity and a compressor to compress the supercritical carbon dioxide. After expanding and doing work in the turbine, the working fluid enters a cooler to cool down, then enters the compressor to be compressed. The pressurized working fluid then enters a heater to absorb heat and rise in temperature before returning to the turbine at high temperature and pressure to do work, thus realizing the Brayton cycle.

[0005] For integrated mechanical components using supercritical carbon dioxide as the working fluid, due to the high pressure differential inside the integrated mechanical components, carbon dioxide from the turbine and compressor can leak through gaps into the chamber where the motor is located, causing the working fluid to accumulate, resulting in excessively high internal pressure, affecting the operation of the overall machine, and reducing system performance. Summary of the Invention

[0006] This application provides a power generation system based on supercritical carbon dioxide Brayton cycle, which can pump out the working fluid accumulated in the chamber and reinject the working fluid into the Brayton cycle with low compression power consumption and high temperature, so that the overall power generation system can operate normally and ensure the overall performance of the system.

[0007] This application provides a power generation system based on supercritical carbon dioxide Brayton cycle. The Brayton cycle is performed using supercritical carbon dioxide as the working fluid. The power generation system includes a main circulation system comprising an integrated component, a heating passage, and a cooling passage. The integrated component is connected between the heating passage and the cooling passage to form an overall loop of the Brayton cycle. An auxiliary circulation system includes a leakage passage and a heat pump circulation loop. The leakage passage is connected between the drain port of the integrated component and the main circulation system. The heat pump circulation loop is connected to the overall loop of the main circulation system via a guide passage. The leakage passage exchanges heat with the heat pump circulation loop via a heat exchange component.

[0008] In the above power generation system based on supercritical carbon dioxide Brayton cycle, the inlet of the leakage flow path is connected to the outlet of the integrated component, and the outlet is connected to the heating passage; the heat pump circulation loop is connected to the cooling passage through the diversion path.

[0009] In the power generation system based on supercritical carbon dioxide Brayton cycle as described above, a leakage cooling element is provided in the leakage flow path between the vent and the heat exchange component. The leakage cooling element is used to cool the working fluid leaking from the vent.

[0010] In the power generation system based on supercritical carbon dioxide Brayton cycle as described above, a reinjection device is provided in the leakage flow path after the bleed-out cooling device. The reinjection device is used to pressurize the working fluid in the leakage flow path and inject it back into the main circulation system.

[0011] In the above-described power generation system based on supercritical carbon dioxide Brayton cycle, the heat exchange components include a first heat exchanger and a second heat exchanger. The first heat exchanger includes a first connecting end and a second connecting end. The first connecting end is connected to the heat pump circulation loop, and the second connecting end is connected to the leakage flow path. The second connecting end is located between the leakage cooling component and the reinjection component. The second heat exchanger includes a third connecting end and a fourth connecting end. The third connecting end is connected to the heat pump circulation loop, and the fourth connecting end is connected to the leakage flow path. The fourth connecting end is located after the reinjection component.

[0012] In the power generation system based on the supercritical carbon dioxide Brayton cycle described above, the heat pump cycle assembly includes a heat pump cycle cooling component, an expansion valve, and a heat pump cycle compressor. The heat pump cycle cooling component and the expansion valve are sequentially arranged on the heat pump cycle loop from the third connecting end to the first connecting end, and the heat pump cycle compressor is arranged on the heat pump cycle loop from the first connecting end to the third connecting end.

[0013] In the power generation system based on supercritical carbon dioxide Brayton cycle as described above, a first cooling element and a second cooling element are provided in the cooling passage. The first end of the diversion passage is connected to the cooling passage between the first cooling element and the second cooling element through a first three-way valve, and the second end of the diversion passage is connected to the heat pump cycle loop between the second heat exchange element and the heat pump cycle compressor through a second three-way valve.

[0014] The above-mentioned power generation system based on supercritical carbon dioxide Brayton cycle includes an integrated component comprising a compressor, a turbine, a motor, and a drive shaft. The compressor, turbine, and motor are coaxially connected via the drive shaft, with the compressor and turbine connected to both ends of the drive shaft and the motor located in the middle of the drive shaft. A heating passage is connected between the compressor outlet and the turbine inlet, and a cooling passage is connected between the turbine outlet and the compressor inlet.

[0015] In the above power generation system based on supercritical carbon dioxide Brayton cycle, a heater is provided in the heating passage, and the leakage passage is connected to the passage between the heater and the compressor outlet through a third three-way valve.

[0016] In the above-mentioned power generation system based on supercritical carbon dioxide Brayton cycle, the integrated component also has a passage gap, through which the compressor and the turbine are connected to the drain port, which is located on the side of the motor near the turbine.

[0017] The power generation system based on supercritical carbon dioxide Brayton cycle in this application includes a main cycle system and an auxiliary cycle system. The main cycle system includes an integrated component, a heating passage, and a cooling passage. The integrated component is connected between the heating passage and the cooling passage to form an overall loop of Brayton cycle, thereby enabling the use of supercritical carbon dioxide as the working fluid to complete energy conversion through Brayton cycle and achieve power generation.

[0018] The integrated component of the main circulation system also has a vent, through which leaked carbon dioxide working fluid can be released during the operation of the integrated component. The auxiliary circulation system includes a leakage flow path and a heat pump circulation loop. The leakage flow path connects the vent and the main circulation system, while the heat pump circulation loop is connected to the overall loop of the main circulation system via a guide path. Since the working fluid leaking from the vent of the integrated component is at a high temperature, it needs to be cooled by the heat exchange components in the heat pump circulation loop. This allows the leaked working fluid to be reinjected into the main circulation system with lower compression power consumption. At the same time, the pressurized leaked working fluid can exchange heat again with the heat exchange components in the heat pump circulation loop to raise its temperature, allowing it to be reinjected into the main circulation system at a higher temperature. This ensures the normal operation of the entire power generation system and guarantees the overall performance of the system. Attached Figure Description

[0019] To more clearly illustrate the technical solutions of the embodiments of this application, the drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in this application. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0020] Figure 1 is a schematic diagram of each loop and path in a power generation system based on supercritical carbon dioxide Brayton cycle according to an embodiment of this application;

[0021] Figure 2 is a schematic diagram of the components in a power generation system based on a supercritical carbon dioxide Brayton cycle according to an embodiment of this application;

[0022] Figure 3 is a temperature entropy diagram of the working fluid and external cooling fluid in each loop and passage of a power generation system based on supercritical carbon dioxide Brayton cycle according to an embodiment of this application. Detailed Implementation

[0023] The features and exemplary embodiments of various aspects of this application will be described in detail below. To make the objectives, technical solutions, and advantages of this application clearer, the application will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain this application and not to limit it. For those skilled in the art, this application can be implemented without some of these specific details. The following description of the embodiments is merely to provide a better understanding of this application by illustrating examples.

[0024] The supercritical carbon dioxide Brayton cycle is a power cycle that can achieve efficient thermoelectric conversion. It typically requires four main components to work together to achieve the cycle: turbine, compressor, heater, and cooler. Among them, the turbine and compressor are rotating components that convert heat into work in the cycle, and their performance is an important factor affecting the cycle performance.

[0025] In the actual operation of a supercritical carbon dioxide Brayton cycle system, to improve system compactness and simplicity, reduce system footprint, and balance axial forces, the compressor and turbine are typically arranged on opposite sides of the same shaft, with the motor positioned in the middle of the shaft, forming an integrated mechanical structure. This integrated mechanical structure is commonly referred to as a TAC (Turbine-Alternator-Compressor). The integrated component utilizes the work generated by the rotation of the turbine blades to drive the compressor to rotate and compress the supercritical carbon dioxide working fluid. Excess work is converted into electrical energy in the motor, thus achieving thermoelectric conversion.

[0026] For integrated mechanical components using supercritical carbon dioxide as the working fluid, the high density of the working fluid allows for a relatively smaller overall size. However, the internal clearance dimensions cannot be significantly reduced due to manufacturing limitations. Therefore, the clearances in integrated mechanical components using supercritical carbon dioxide are larger than those in conventional turbines using air or water, leading to more severe leakage. In these integrated mechanical components, carbon dioxide leaking from the compressor and turbine flows into the motor chamber through seals, bearings, and other components. If this carbon dioxide is not discharged in time, the pressure inside the chamber increases. The high-pressure, high-density carbon dioxide rotates along with the rotor components (motor, bearings, etc.) in the rotor-stator gap, generating significant frictional losses. This frictional loss is called wind resistance loss, which is proportional to the working fluid density and the cube of the rotor speed. The higher the chamber pressure, the greater the wind resistance loss generated by the rotor components, resulting in a greater heat load. This not only exposes the components inside the chamber to the risk of overheating failure but also reduces system performance.

[0027] Currently, the main approach to addressing internal leakage and air resistance losses in integrated mechanical components is to use a pump to extract the leaking flow, cool and pressurize it, and then reinject it into the main circulation, i.e., the Brayton cycle in which the integrated component operates. This not only recovers the leaking flow but also keeps the pressure within the chamber low, meeting the operational requirements of higher speeds and lower leakage for the integrated component. During the extraction process, if the pressure within the chamber is relatively high, the cooling system at room temperature can liquefy the extracted leaking carbon dioxide, allowing for reinjection using only a pump. However, if the chamber pressure is low, the leaking carbon dioxide remains gaseous after cooling, requiring compression with a compressor. This not only increases power consumption but also presents the problem of excessively high working fluid temperature at the compressor outlet due to excessively high pressure ratios, potentially causing the compressor to malfunction. Therefore, further cooling of the leaking carbon dioxide is necessary. Additionally, increasing the speed or reducing the leakage rate can lead to an increase in the internal temperature of the integrated mechanical component. Further reducing the chamber pressure in these situations can significantly reduce air resistance losses, thereby lowering the internal temperature. Therefore, this application proposes a power generation system based on supercritical carbon dioxide Brayton cycle, which can extract the working fluid accumulated in the chamber with low power consumption, while maintaining a low chamber pressure and reinjecting the working fluid into the Brayton cycle at a high temperature, thereby enabling the overall power generation system to operate normally and ensuring the overall performance of the system. At the same time, it can also enable the integrated component chamber to operate at a lower pressure, further meeting the operating requirements of higher component speed and lower leakage.

[0028] As shown in Figures 1 and 2, this application provides a power generation system based on supercritical carbon dioxide Brayton cycle. The Brayton cycle is performed using supercritical carbon dioxide as the working fluid. The power generation system includes a main circulation system 100, comprising an integrated component 10, a heating passage 20, and a cooling passage 30. The integrated component 10 is connected between the heating passage 20 and the cooling passage 30 to form an overall loop of the Brayton cycle. An auxiliary circulation system 200 includes a leakage passage 40 and a heat pump circulation loop 50. The leakage passage 40 is connected between the drain port 11 of the integrated component 10 and the compressor outlet of the main circulation system 100. The heat pump circulation loop 50 is connected to the overall loop of the main circulation system 100 via a guide passage 60. The leakage passage 40 exchanges heat with the heat pump circulation loop 50 via a heat exchange component 80.

[0029] It should be noted that supercritical carbon dioxide refers to the state of carbon dioxide when the temperature and pressure exceed its critical points (30.98℃ and 7.38MPa). At this point, carbon dioxide has the characteristics of both liquid and gas, such as high density, low viscosity and good heat transfer performance.

[0030] Figure 1 is a schematic diagram of each loop and path in the power generation system, and Figure 2 is a schematic diagram of each component in the power generation system. In Figures 1 and 2, the solid lines represent the circuit diagrams of the main circulation loop and the heat pump circulation loop 50 in the main circulation system 100, with carbon dioxide as the working fluid inside; the dashed lines represent the circuit diagram of the leakage flow path 40, with leaked carbon dioxide as the working fluid inside; and the dotted lines represent the external ambient temperature cooling fluid introduced to cool the carbon dioxide working fluid.

[0031] In this embodiment, the integrated component 10 includes a compressor 12, a turbine 13, a motor 14, and a drive shaft 15. The compressor 12, turbine 13, and motor 14 are coaxially connected via the drive shaft 15. The compressor 12 and turbine 13 are respectively connected to both ends of the drive shaft 15, and the motor 14 is located in the middle of the drive shaft 15. The turbine 13 can convert the energy in the supercritical carbon dioxide working fluid into mechanical energy. When the supercritical carbon dioxide flows through the impeller of the turbine 13, it impacts the blades and drives the impeller to rotate, thereby enabling the turbine 13 to drive the drive shaft 15 to rotate together. This causes the compressor 12 and motor 14 to rotate with the drive shaft 15. The rotation of the compressor 12 can compress the supercritical carbon dioxide, and the rotation of the motor 14 can output electrical energy, realizing the power generation function of the integrated component 10.

[0032] In specific implementation, the power generation system based on supercritical carbon dioxide Brayton cycle of this application includes a main circulation system 100 and an auxiliary circulation system 200. The main circulation system 100 includes an integrated component 10, a heating passage 20 and a cooling passage 30. The integrated component 10 is connected between the heating passage 20 and the cooling passage 30 to form an overall loop of Brayton cycle, thereby enabling the use of supercritical carbon dioxide as the working fluid and the completion of energy conversion through Brayton cycle to achieve power generation.

[0033] The integrated component 10 of the main circulation system 100 also has a drain port 11, through which the carbon dioxide working fluid leaked during the operation of the integrated component 10 can be drained. The auxiliary circulation system 200 includes a leakage flow path 40 and a heat pump circulation loop 50. The leakage flow path 40 is connected between the vent 11 and the main circulation system 100, while the heat pump circulation loop 50 is connected to the overall loop of the main circulation system 100 via a guide flow path 60. Since the working fluid leaking from the vent 11 of the integrated component 10 has a high temperature, when the working fluid passes through the leakage flow path 40, it is first cooled by external cooling fluid through the vent cooling component 41. Subsequently, in the heat pump circulation loop 50, the working fluid injected by the main circulation system 100 will further cool the leaked carbon dioxide in the leakage flow path 40 to a liquid state through the heat exchange component 80, so that the leaked working fluid can be reinjected into the Brayton cycle in a liquid state with low compression work consumption. At the same time, the pressurized leaked working fluid can also exchange heat with the heat exchange component 80 in the heat pump circulation loop 50 to raise its temperature, so that the leaked working fluid can be reinjected into the Brayton cycle at a higher temperature, thereby ensuring the normal operation of the overall power generation system and guaranteeing the overall performance of the system.

[0034] Furthermore, since the working fluid injected by the main circulation system 100 will further cool the leaked carbon dioxide in the leakage flow path 40 to a liquid state through the heat exchange component 80, the leaked working fluid can be reinjected into the Brayton cycle with lower compression power consumption. Therefore, this system can enable the chamber of the integrated component 10 to operate at a lower pressure, generate less wind resistance loss, reduce the processing requirements of the high-pressure wall of the integrated component 10, further meet the operating requirements of the integrated component 10 for higher speed and lower leakage, and enable the overall power generation system to have a wider range of operating conditions.

[0035] Furthermore, if the overall flow rate of the circulating working fluid in the main circulation system 100 is high, the working fluid in the main circulation system 100 can be further introduced into the internal volume of the heat pump circulation loop 50 through the diversion path 60 to reduce the flow rate in the main circulation system 100. Conversely, if the overall flow rate of the circulating working fluid in the main circulation system 100 is low, the working fluid in the internal volume of the heat pump circulation loop 50 can be introduced into the main circulation system 100 through the diversion path 60 to increase the flow rate in the main circulation system 100. Therefore, the heat pump circulation loop 50 can not only regulate the temperature of the working fluid in the leakage path 40, but also regulate and buffer the flow rate of the circulating working fluid in the main circulation system 100, ensuring that the flow rate of the working fluid in the main circulation system 100 meets the circulation requirements.

[0036] In the supercritical carbon dioxide Brayton cycle-based power generation system of this application embodiment, the inlet of the leakage flow path 40 is connected to the vent 11 of the integrated component 10, and the outlet is connected to the heating passage 20; the heat pump circulation loop 50 is connected to the cooling passage 30 through the guide flow path 60.

[0037] In specific implementation, the heat pump circulation loop 50 is connected to the cooling passage 30 through the lead-in passage 60. The cooler working fluid in the cooling passage 30 can enter the heat pump circulation loop 50 through the lead-in passage, while the working fluid leaking from the drain port 11 is in a warmer state when it enters the leakage passage 40. After the working fluid in the leakage passage 40 exchanges heat with the external cooling fluid passing through the drain cooling component 41 and the working fluid in the heat pump circulation loop 50 through the heat exchange component 80, the working fluid in the leakage passage 40 can be cooled. After being pressurized in the reinjection component 42, the cooled working fluid can exchange heat again with the working fluid in the heat pump circulation loop 50 through the heat exchange component 80 to absorb heat and increase its temperature. Finally, it is reinjected into the heating passage 20 through the leakage passage 40.

[0038] In this embodiment, the heating passage 20 is connected between the outlet of the compressor 12 and the inlet of the turbine 13. A heater 21 is provided on the heating passage 20 for heating the working fluid flowing through the heating passage 20. The cooling passage 30 is connected between the outlet of the turbine 13 and the inlet of the compressor 12. A first cooling element 31 and a second cooling element 32 are provided on the cooling passage 30 for cooling the working fluid flowing through the cooling passage 30.

[0039] In the Brayton cycle implemented in the main circulation system 100, the supercritical carbon dioxide, after being heated by the heater 21 of the heating passage 20, is in a high-temperature and high-pressure state. The high-temperature and high-pressure supercritical carbon dioxide enters through the inlet of the turbine 13, which can convert its internal energy into mechanical energy for rotation. The supercritical carbon dioxide discharged from the outlet of the turbine 13 to the cooling passage 30 is in a high-temperature and low-pressure state. After being cooled sequentially by the first cooling element 31 and the second cooling element 32 of the cooling passage 30, the temperature of the supercritical carbon dioxide decreases and it is transformed into a low-temperature and low-pressure state. The supercritical carbon dioxide in the low-temperature and low-pressure state enters the compressor 12 through the inlet of the compressor 12 for compression to achieve pressure increase. The supercritical carbon dioxide discharged from the outlet of the compressor 12 to the inlet of the heating passage 20 is in a low-temperature and high-pressure state. Finally, after being heated by the heater 21 of the heating passage 20, it is transformed into a high-temperature and high-pressure state, forming a complete Brayton cycle.

[0040] The supercritical carbon dioxide Brayton cycle-based power generation system of this application embodiment includes a leakage cooling element 41 on the leakage flow path 40 between the vent 11 and the heat exchange assembly 80. The leakage cooling element 41 is used to cool the working fluid leaking from the vent 11. It should be noted that this leakage cooling element 41 exchanges heat with the leaking working fluid in the leakage flow path 40 through an externally introduced ambient temperature cooling fluid.

[0041] In specific implementation, a leakage cooling component 41 is installed on the leakage flow path 40 between the vent 11 and the heat exchange component 80. This component can initially cool the working fluid that leaks from the vent 11 to the leakage flow path 40. After initial cooling, the working fluid reaches the heat exchange component 80. The working fluid in the heat pump circulation loop 50 further cools the working fluid in the leakage flow path 40 through the heat exchange component 80. This allows the working fluid in the leakage flow path 40 to be cooled to a liquid state under low pressure, facilitating liquid compression in the leakage flow path 40 and reducing overall power consumption.

[0042] In the power generation system based on supercritical carbon dioxide Brayton cycle of this application embodiment, a reinjection component 42 is provided on the leakage flow path 40 after the venting cooling component 41. The reinjection component 42 is a pump body used to pressurize and inject the working fluid in the leakage flow path 40 back to the main circulation system 100.

[0043] In practice, after cooling, the working fluid in the leakage flow path 40 is converted into a liquid state, and the return component 42 can pump the liquid working fluid back to the heating passage 20 at a lower power.

[0044] The power generation system based on supercritical carbon dioxide Brayton cycle according to the embodiments of this application includes a heat exchange component 80 comprising a first heat exchange component 81 and a second heat exchange component 82. The first heat exchange component 81 includes a first connecting end 811 and a second connecting end 812. The first connecting end 811 is connected to the heat pump circulation loop 50, and the second connecting end 812 is connected to the leakage flow path 40, and the second connecting end 812 is located between the venting cooling component 41 and the reinjection component 42. The second heat exchange component 82 includes a third connecting end 821 and a fourth connecting end 822. The third connecting end 821 is connected to the heat pump circulation loop 50, and the fourth connecting end 822 is connected to the leakage flow path 40, and the fourth connecting end 822 is located after the reinjection component 42.

[0045] In specific implementation, during heat exchange, the working fluid in the heat pump circulation loop 50 cools the working fluid in the leakage flow path 40 through the second connection end 812 via the first connection end 811 of the first heat exchange component 81. The working fluid cooled by the second connection end 812 can be pumped by the reinjection component 42 to the fourth connection end 822 of the second heat exchange component 82. At this time, the working fluid with a higher temperature in the heat pump circulation loop 50 can heat the working fluid in the fourth connection end 822 via the third connection end 821, so that the leaked working fluid can be reinjected into the heating passage 20 at a higher temperature and directly participate in the main circulation.

[0046] The power generation system based on supercritical carbon dioxide Brayton cycle in this application embodiment includes a heat pump cycle assembly 70 comprising a heat pump cycle cooling component 71, an expansion valve 72, and a heat pump cycle compressor 73. The heat pump cycle cooling component 71 and the expansion valve 72 are sequentially disposed on the heat pump cycle loop 50 from the third connecting end 821 to the first connecting end 811, and the heat pump cycle compressor 73 is disposed on the heat pump cycle loop 50 from the first connecting end 811 to the third connecting end 821.

[0047] In the supercritical carbon dioxide Brayton cycle-based power generation system of this application embodiment, a first cooling element 31 and a second cooling element 32 are provided on the cooling passage 30. The first end of the guide passage 60 is connected to the cooling passage 30 between the first cooling element 31 and the second cooling element 32 through a first three-way valve 61. The second end of the guide passage 60 is connected to the heat pump cycle loop 50 between the second heat exchange element 82 and the heat pump cycle compressor 73 through a second three-way valve 62.

[0048] In practice, the working fluid, after being cooled by the first cooling element 31, has a reduced temperature but is still in a relatively hot state. Part of the hot working fluid enters the diversion path 60 through the first three-way valve 61, and the other part enters the second cooling element 32 through the first three-way valve 61 to be cooled and continue the main circulation. The part of the working fluid that enters the diversion path 60 reaches the second three-way valve 62 and enters the heat pump circulation loop 50 through the second three-way valve 62 to perform heat pump circulation.

[0049] During heat pump circulation in the heat pump loop 50, the heat pump loop assembly 70 and the heat exchange assembly 80 work together in the heat pump loop. Specifically, the second heat exchanger 82, the heat pump loop cooling assembly 71, the expansion valve 72, the first heat exchanger 81, and the heat pump loop compressor 73 are sequentially connected in the heat pump loop 50, and the working fluid circulates in the heat pump loop 50 in the above order.

[0050] As shown in Figure 3, Figure 3 is a temperature entropy diagram of the working fluid and external cooling fluid in each loop and passage. The dashed line is the carbon dioxide saturation line, the solid line is the temperature entropy change of the working fluid flowing through each component in the heat pump circulation loop 50, the single-dotted line is the temperature change of the external ambient temperature cooling fluid, and the double-dotted line is the temperature change of the working fluid in the leakage passage 40. After the hotter working fluid in the diversion path 60 enters the heat pump circulation loop 50 through the second three-way valve 62, as shown by curves 2 to 2p (solid line), the hotter working fluid enters the third connecting end 821 to release heat, thereby raising the temperature of the working fluid in the fourth connecting end 822. At this time, the temperature entropy change of the working fluid in the leakage path 40 in the fourth connecting end 822 is shown by the double-dotted line at the top in Figure 3. As shown by curves 2p to 3 (solid line), the initially cooled working fluid is further cooled by the external ambient temperature cooling fluid in the heat pump circulation cooling component 71. At this time, the temperature change of the ambient temperature cooling fluid is shown by the single-dotted line in Figure 3. As shown by curves 3 to 4 (solid line), the temperature change of the ambient temperature cooling fluid is shown by the single-dotted line in Figure 3. After being fully cooled, the working fluid is depressurized through the expansion valve 72. As shown by curves 4 to 1 in the solid line section, the depressurized working fluid absorbs heat from the working fluid in the second connection end 812 through the first connection end 811 of the first heat exchanger 81, thereby cooling the working fluid in the leakage flow path 40 at the second connection end 812. At this time, the temperature change of the working fluid in the leakage flow path 40 in the second connection end 812 is shown by the double-dotted line at the bottom of Figure 3. As shown by curves 1 to 2 in the solid line section, the heated working fluid reaches the heat pump cycle compressor 73 for pressurization. The pressurized working fluid finally reaches the second heat exchanger 82 and the heat pump cycle cooling component 71 for cooling to complete the complete cycle. Therefore, in the heat pump circulation loop 50, the working fluid of the main circulation is used for heat pump circulation, and the working fluid passing through the leakage flow path 40 is cooled and heated sequentially through this circulation process. This allows the working fluid in the leakage flow path 40 to not only be compressed in liquid form, but also to be reinjected into the main circulation at a higher temperature. There is no need to use heating or cooling structures outside the power generation system, which achieves energy saving.

[0051] It should be noted that when the heat pump is circulating in the heat pump loop 50, the end of the second three-way valve 62 used to connect the diversion path 60 is closed so that the heat pump loop 50 circulates on its own. It will only be opened when the working fluid in the main loop needs to be diverted to the heat pump loop 50, so as to achieve regulation and buffering of the working fluid in the main loop.

[0052] In the supercritical carbon dioxide Brayton cycle-based power generation system of this application embodiment, a heater 21 is provided on the heating passage 20, and a leakage passage 40 is connected to the passage between the heater 21 and the outlet of the compressor 12 through a third three-way valve 43.

[0053] In specific implementation, the leakage flow path 40 is connected to the passage between the heater 21 and the outlet of the compressor 12 through the third three-way valve 43. When the working fluid leaking in the leakage flow path 40 is reinjected into the main circulation through the third three-way valve 43, it merges with the working fluid at the outlet of the compressor 12 and enters the heater 21 for heating. Since the working fluid leaking in the leakage flow path 40 is cooled after passing through the venting cooling component 41 and the heat exchange component 80, it can be compressed by the pump in liquid form, avoiding the situation where the working fluid overheats under high pressure ratio conditions when the leaking working fluid is reinjected by the compressor.

[0054] In the supercritical carbon dioxide Brayton cycle-based power generation system of this application embodiment, the integrated component 10 also has a through gap 16 inside, and the compressor 12 and the turbine 13 are both connected to the drain port 11 through the through gap 16. The drain port 11 is located on the side of the motor 14 near the turbine 13.

[0055] The integrated component 10 also includes a seal 17, a radial bearing 18, and a thrust bearing 19. The seal 17 and the radial bearing 18 are provided between the compressor 12 and the motor 14, as well as between the turbine 13 and the motor 14. The thrust bearing 19 is located between the seal 17 and the radial bearing 18 on one side of the compressor 12.

[0056] The gap 16 surrounds all the parts inside the integrated component 10 and is located on the periphery of each part. The working fluid leaking from the compressor 12 and turbine 13 can enter the gap 16. Since the working fluid at turbine 13 has been heated by the heating passage 20, its temperature is higher, while the working fluid at compressor 12 has a lower temperature. The drain port 11 is located on the side of motor 14 near turbine 13. The higher-temperature working fluid at turbine 13 will not pass through motor 14 when flowing through the gap 16, thus preventing motor 14 from heating up and ensuring normal operation of motor 14. Meanwhile, the lower-temperature working fluid at compressor 12 can cool motor 14 when passing through motor 14.

[0057] It should be noted that, in this document, relational terms such as "first" and "second" are used merely to distinguish one entity or operation from another, and do not necessarily require or imply any such actual relationship or order between these entities or operations. Furthermore, the terms "comprising," "including," or any other variations thereof are intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent to such a process, method, article, or apparatus. Without further limitations, an element defined by the phrase "comprising..." does not exclude the presence of additional identical elements in the process, method, article, or apparatus that includes said element.

[0058] The above description is merely a specific implementation of this application. Those skilled in the art will clearly understand that, for the sake of convenience and brevity, the specific working processes of the systems, modules, and units described above can be referred to the corresponding processes in the foregoing method embodiments, and will not be repeated here. It should be understood that the protection scope of this application is not limited thereto. Any person skilled in the art can easily conceive of various equivalent modifications or substitutions within the technical scope disclosed in this application, and these modifications or substitutions should all be covered within the protection scope of this application.

Claims

1. A power generation system based on a supercritical carbon dioxide Brayton cycle, wherein, The power generation system, which uses supercritical carbon dioxide as the working fluid in a Brayton cycle, includes: The main circulation system (100) includes an integrated component (10), a heating passage (20) and a cooling passage (30), wherein the integrated component (10) is connected between the heating passage (20) and the cooling passage (30) to form an overall loop of the Brayton cycle; The auxiliary circulation system (200) includes a leakage flow path (40) and a heat pump circulation loop (50). The leakage flow path (40) is connected between the drain port (11) of the integrated component (10) and the overall loop of the main circulation system (100). The heat pump circulation loop (50) is connected to the main circulation system (100) through a guide flow path (60). The leakage flow path (40) exchanges heat with the heat pump circulation loop (50) through a heat exchange assembly (80).

2. The power generation system based on supercritical carbon dioxide Brayton cycle according to claim 1, wherein, The inlet of the leakage flow path (40) is connected to the outlet (11) of the integrated component (10), and the outlet is connected to the heating passage (20); The heat pump circulation loop (50) is connected to the cooling passage (30) through the drainage path (60).

3. The power generation system based on supercritical carbon dioxide Brayton cycle according to claim 1 or 2, wherein, A leakage cooling element (41) is provided on the leakage flow path (40) between the vent (11) and the heat exchange assembly (80), and the leakage cooling element (41) is used to cool the working fluid leaking from the vent (11).

4. The power generation system based on supercritical carbon dioxide Brayton cycle according to claim 3, wherein, A reinjection component (42) is provided on the leakage flow path (40) after the leakage cooling component (41). The reinjection component (42) is used to pressurize and inject the working fluid in the leakage flow path (40) back to the main circulation system (100).

5. The power generation system based on supercritical carbon dioxide Brayton cycle according to claim 4, wherein, The heat exchange assembly (80) includes a first heat exchange component (81) and a second heat exchange component (82). The first heat exchange component (81) includes a first connecting end (811) and a second connecting end (812). The first connecting end (811) is connected to the heat pump circulation loop (50), and the second connecting end (812) is connected to the leakage flow path (40). The second connecting end (812) is located between the leakage cooling component (41) and the reinjection component (42). The second heat exchange component (82) includes a third connecting end (821) and a fourth connecting end (822). The third connecting end (821) is connected to the heat pump circulation loop (50), and the fourth connecting end (822) is connected to the leakage flow path (40). The fourth connecting end (822) is located after the reinjection component (42).

6. The power generation system based on supercritical carbon dioxide Brayton cycle according to claim 5, wherein, The heat pump circulation loop (50) is provided with a heat pump circulation assembly (70), which includes a heat pump circulation cooling component (71), an expansion valve (72), and a heat pump circulation compressor (73). The heat pump circulation cooling component (71) and the expansion valve (72) are sequentially disposed on the heat pump circulation loop (50) from the third connecting end (821) to the first connecting end (811), and the heat pump circulation compressor (73) is disposed on the heat pump circulation loop (50) from the first connecting end (811) to the third connecting end (821).

7. The power generation system based on supercritical carbon dioxide Brayton cycle according to claim 6, wherein, The cooling passage (30) is provided with a first cooling element (31) and a second cooling element (32). The first end of the diversion passage (60) is connected to the cooling passage (30) between the first cooling element (31) and the second cooling element (32) through a first three-way valve (61). The second end of the diversion passage (60) is connected to the heat pump circulation loop (50) between the second heat exchange element (82) and the heat pump circulation compressor (73) through a second three-way valve (62).

8. The power generation system based on supercritical carbon dioxide Brayton cycle according to claim 1 or 2, wherein, The integrated component (10) includes a compressor (12), a turbine (13), a motor (14), and a drive shaft (15). The compressor (12), the turbine (13), and the motor (14) are coaxially connected through the drive shaft (15). The compressor (12) and the turbine (13) are respectively connected to the two ends of the drive shaft (15), and the motor (14) is located in the middle of the drive shaft (15). The heating passage (20) is connected between the outlet of the compressor (12) and the inlet of the turbine (13), and the cooling passage (30) is connected between the outlet of the turbine (13) and the inlet of the compressor (12).

9. The power generation system based on supercritical carbon dioxide Brayton cycle according to claim 8, wherein, A heater (21) is provided on the heating passage (20), and the leakage passage (40) is connected to the passage between the heater (21) and the outlet of the compressor (12) through a third three-way valve (43).

10. The power generation system based on supercritical carbon dioxide Brayton cycle according to claim 8, wherein, The integrated component (10) also has a passage gap (16) inside, through which the compressor (12) and the turbine (13) are connected to the drain port (11) via the passage gap (16), and the drain port (11) is located on the side of the motor (14) near the turbine (13).

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