Power generation system based on supercritical carbon dioxide brayton cycle

Abstract

The application discloses a supercritical carbon dioxide Brayton cycle-based power generation system, which comprises a main cycle system, an auxiliary cycle system and a heat exchange assembly. The main cycle system comprises 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. The auxiliary cycle system comprises a leakage flow passage and a heat pump cycle loop. The leakage flow passage is connected between a leakage port of the integrated component and the main cycle system. The heat pump cycle loop is connected with the overall loop of the main cycle system through a flow guide passage. The leakage flow passage exchanges heat with the heat pump cycle loop through the heat exchange assembly. The supercritical carbon dioxide Brayton cycle-based power generation system can recycle working medium leaked from the chamber of the integrated component, and the working medium can be injected into the Brayton cycle at a lower compression power consumption and a higher temperature.

Description

Technical Field

[0001] The present application belongs to the field of thermal power generation technology, and in particular relates to a power generation system based on a supercritical carbon dioxide Brayton cycle. Background Art

[0002] In the field of thermal power generation, the supercritical CO2 Brayton cycle is often used to convert heat energy into electrical energy. This cycle uses high-temperature, high-pressure supercritical CO2 to drive a turbine, which in turn drives a motor to generate electricity and a compressor to compress the supercritical CO2. After expanding and performing work in the turbine, the working fluid enters a cooler for cooling, then enters a compressor for compression. The pressurized working fluid then enters a heater to absorb heat and heat up, before entering the turbine again at a high temperature and high pressure to perform work, completing the Brayton cycle.

[0003] For integrated component machines whose working fluid is supercritical carbon dioxide, due to the high pressure difference inside the integrated component machine, the carbon dioxide at the turbine and compressor will leak into the chamber where the motor is located through the gap, causing the working fluid to accumulate, making the internal pressure too high, affecting the operation of the entire machine and reducing system performance. Summary of the Invention

[0004] The present application provides a power generation system based on a supercritical carbon dioxide Brayton cycle, which can pump out the working fluid accumulated in the chamber and at the same time inject the working fluid back into the Brayton cycle with lower compression power consumption and higher temperature, so that the overall power generation system can operate normally and ensure the overall performance of the system.

[0005] The present application provides a power generation system based on a supercritical carbon dioxide Brayton cycle, wherein the Brayton cycle is carried out using supercritical carbon dioxide as a working fluid. The power generation system includes a main circulation system, including 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, including a leakage flow passage and a heat pump circulation loop. The leakage flow passage is connected between the discharge 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 through a drainage passage. The leakage flow passage performs heat exchange with the heat pump circulation loop through a heat exchange component.

[0006] As described above, the power generation system based on the supercritical carbon dioxide Brayton cycle, wherein the inlet of the leakage flow path is connected to the drain port of the integrated component, and the outlet is connected to the heating path; the heat pump circulation loop is connected to the cooling path through the drainage path.

[0007] In the power generation system based on the supercritical carbon dioxide Brayton cycle as described above, a leakage flow cooling member is provided in the leakage flow path between the leakage port and the heat exchange component, and the leakage cooling member is used to cool the working medium discharged from the leakage port.

[0008] As described above, in the power generation system based on the supercritical carbon dioxide Brayton cycle, a return component is provided on the leakage flow path behind the leakage flow cooling component, and the return component is used to pressurize the working fluid in the leakage flow path and inject it back into the main circulation system.

[0009] As described above, the power generation system based on the supercritical carbon dioxide Brayton cycle, wherein the heat exchange component includes a first heat exchange element and a second heat exchange element, the first heat exchange element includes a first connecting end and a second connecting end, the first connecting end is connected to the heat pump circulation loop, the second connecting end is connected to the leakage flow path, and the second connecting end is arranged between the leakage flow cooling element and the return injection element; the second heat exchange element includes a third connecting end and a fourth connecting end, the third connecting end is connected to the heat pump circulation loop, the fourth connecting end is connected to the leakage flow path, and the fourth connecting end is arranged after the return injection element.

[0010] As described above, a power generation system based on a supercritical carbon dioxide Brayton cycle is provided, wherein a heat pump circulation component includes a heat pump circulation cooling element, an expansion valve and a heat pump circulation compressor. The heat pump circulation cooling element and the expansion valve are sequentially arranged on the heat pump circulation loop from the third connecting end to the first connecting end, and the heat pump circulation compressor is arranged on the heat pump circulation loop from the first connecting end to the third connecting end.

[0011] As described above, a power generation system based on a supercritical carbon dioxide Brayton cycle is provided with a first cooling element and a second cooling element on the cooling passage, a first end of the drainage passage is connected to the cooling passage between the first cooling element and the second cooling element through a first three-way valve, and a second end of the drainage passage is connected to the heat pump circulation loop between the second heat exchange element and the heat pump circulation compressor through a second three-way valve.

[0012] As described above, the power generation system based on the supercritical carbon dioxide Brayton cycle comprises an integrated component including a compressor, a turbine, a motor and a drive shaft. The compressor, the turbine and the motor are coaxially connected through the drive shaft. The compressor and the turbine are respectively connected to the two ends of the drive shaft, and the motor is arranged in the middle of the drive shaft. The heating path is connected between the outlet of the compressor and the inlet of the turbine, and the cooling path is connected between the outlet of the turbine and the inlet of the compressor.

[0013] In the above-mentioned power generation system based on the supercritical carbon dioxide Brayton cycle, a heater is provided on the heating passage, and the leakage flow passage is connected to the passage between the heater and the outlet of the compressor through a third three-way valve.

[0014] As described above, the power generation system based on the supercritical carbon dioxide Brayton cycle has a through gap inside the integrated component, and the compressor and the turbine are connected to the drain port through the through gap, and the drain port is provided on the side of the motor close to the turbine.

[0015] The power generation system based on the supercritical carbon dioxide Brayton cycle of the present application includes a main circulation system and an auxiliary circulation system. The main circulation system includes an integrated component, a heating path and a cooling path. The integrated component is connected between the heating path and the cooling path to form an overall loop of the Brayton cycle, so that supercritical carbon dioxide can be used as a working fluid to complete energy conversion through the Brayton cycle and achieve power generation effect.

[0016] The integrated component of the main circulation system also has a drain port, through which the carbon dioxide working fluid leaked during the operation of the integrated component can be discharged. The auxiliary circulation system includes a leakage flow path and a heat pump circulation loop, wherein the leakage flow path is connected between the drain port and the main circulation system, and the heat pump circulation loop is connected to the overall loop of the main circulation system through the drainage path. Since the working fluid leaked from the drain port of the integrated component has a high temperature, it needs to be cooled by the heat exchange component in the heat pump circulation loop, so that the leaked working fluid can be reinjected into the main circulation system with lower compression power consumption. At the same time, the pressurized leaked working fluid can also exchange heat with the heat exchange component in the heat pump circulation loop again to increase the temperature, so that it can be reinjected into the main circulation system at a higher temperature, so that the overall power generation system can operate normally and ensure the overall performance of the system. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the following is a brief introduction to the drawings required for use in the embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without any creative work.

[0018] Figure 1 Schematic diagram of various circuits and pathways in a power generation system based on a supercritical carbon dioxide Brayton cycle according to an embodiment of the present application;

[0019] Figure 2 Schematic diagram of various components in a power generation system based on a supercritical carbon dioxide Brayton cycle according to an embodiment of the present application;

[0020] Figure 3 This is a temperature entropy diagram of the working fluid and the external cooling fluid in each circuit and passage in the power generation system based on the supercritical carbon dioxide Brayton cycle in an embodiment of the present application.

[0021] Description of Figure Numbers:

[0022] 100, main circulatory system; 200, auxiliary circulatory system;

[0023] 10. Integrated component; 11. Drain port; 12. Compressor; 13. Turbine; 14. Motor; 15. Drive shaft; 16. Through gap; 17. Seal; 18. Radial bearing; 19. Thrust bearing; 20. Heating passage; 21. Heater; 30. Cooling passage; 31. First cooling element; 32. Second cooling element; 40. Leakage flow passage; 41. Leakage cooling element; 42. Re-injection element; 43. Third three-way valve; 50. Heat pump circulation loop; 60. Drainage passage; 61. First three-way valve; 62. Second three-way valve; 70. Heat pump circulation assembly; 71. Heat pump circulation cooling element; 72. Expansion valve; 73. Heat pump circulation compressor; 80. Heat exchange assembly; 81. First heat exchange element; 811. First connecting end; 812. Second connecting end; 82. Second heat exchange element; 821. Third connecting end; 822. Fourth connecting end. DETAILED DESCRIPTION

[0024] The features and exemplary embodiments of various aspects of the present application will be described in detail below. In order to make the purpose, technical solutions and advantages of the present application clearer, the present application will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only intended to explain the present application, rather than to limit the present application. For those skilled in the art, the present application can be implemented without the need for some of these specific details. The following description of the embodiments is merely to provide a better understanding of the present application by illustrating the examples of the present application.

[0025] The supercritical carbon dioxide Brayton cycle is a power cycle that can achieve efficient heat-to-electricity conversion. It usually requires four major components: a turbine, a compressor, a heater, and a cooler to realize the cycle. Among them, the turbine and compressor are the rotating components for heat and power conversion in the cycle, and their performance is an important factor affecting the cycle performance.

[0026] In the actual operation of a supercritical carbon dioxide Brayton cycle system, to improve the system's compactness and simplicity, reduce its 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, forming an integrated mechanical structure. This integrated mechanical structure is often referred to as a TAC (Turbine-Alternator-Compressor). The integrated structure utilizes the power generated by the rotation of the turbine blades to drive the compressor, which then rotates together to compress the supercritical carbon dioxide working fluid. Excess power is converted into electricity in the motor, thereby achieving thermoelectric conversion.

[0027] For integrated machinery using supercritical carbon dioxide as the working fluid, the high density of the working fluid allows for a relatively small size. However, due to limitations in processing technology, internal gaps cannot be significantly reduced. Therefore, the gaps in integrated machinery using supercritical carbon dioxide as the working fluid are larger than those in conventional turbomachinery using air or water, resulting in more severe leakage. In integrated machinery, carbon dioxide leaking from the compressor and turbine flows through seals, bearings, and other components into the chamber where the motor resides. If this carbon dioxide is not promptly discharged, the pressure inside the chamber will increase. The high-pressure, high-density carbon dioxide will rotate with the high-speed rotation of the motor, bearings, and other rotor components within the rotor-stator gap, generating significant friction losses. This friction loss is called windage, and it is proportional to the working fluid density and the cube of the rotor speed. Higher chamber pressure increases the windage losses caused by the rotating rotor components, resulting in greater heat loads. This not only puts components within the chamber at risk of overheating and failure, but also degrades system performance.

[0028] Currently, the main approach to addressing internal leakage and windage losses within integrated components is to extract the leaked carbon dioxide using a pump, cool it, and pressurize it before reinjecting it into the main cycle, the Brayton cycle within which the integrated component resides. This not only recovers the leaked carbon dioxide but also reduces the pressure within the chamber, meeting the requirements for higher speeds and lower leakage within the integrated component. During the extraction process, if the chamber pressure is relatively high, a cooling system at room temperature can liquefy the extracted leaked carbon dioxide, allowing reinjection using only the pump. However, if the chamber pressure is low, the leaked carbon dioxide remains gaseous after cooling, requiring compression by a compressor. This not only increases power consumption but also poses the risk of excessively high working fluid temperatures at the compressor outlet when compression is performed at excessively high pressure ratios, potentially causing compressor failure. Therefore, further cooling of the leaked carbon dioxide is necessary. Furthermore, increasing the speed or reducing the leakage will cause the temperature of the internal components of the integrated component to rise. Further reducing the chamber pressure would significantly reduce windage losses and, consequently, the internal temperature. Therefore, the present application proposes a power generation system based on the supercritical carbon dioxide Brayton cycle, which can extract the working fluid accumulated in the chamber with lower power consumption, while maintaining a lower chamber pressure, and injecting the working fluid back into the Brayton cycle at a higher temperature, so that the overall power generation system can operate normally, 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 speed and lower leakage of the components.

[0029] like Figure 1 and Figure 2As shown, an embodiment of the present application provides a power generation system based on a supercritical carbon dioxide Brayton cycle, wherein the Brayton cycle is carried out using supercritical carbon dioxide as a working fluid, and the power generation system includes a main circulation system 100, including an integrated component 10, a heating passage 20 and a cooling passage 30, and 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, including a leakage flow passage 40 and a heat pump circulation loop 50, the leakage flow passage 40 is connected between the discharge 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 through the drainage passage 60, and the leakage flow passage 40 performs heat exchange with the heat pump circulation loop 50 through the heat exchange component 80.

[0030] It should be noted that supercritical carbon dioxide refers to the state of carbon dioxide when the temperature and pressure exceed its critical point (30.98°C and 7.38MPa). At this time, carbon dioxide has the characteristics of both liquid and gas, such as high density, low viscosity and good heat transfer performance.

[0031] Figure 1 This is a schematic diagram of the various circuits and pathways in the power generation system. Figure 2 A schematic diagram of the components in the power generation system. Figure 1 and Figure 2 In the figure, the solid line represents the circuit diagram of the main circulation and heat pump circulation loop 50 in the main circulation system 100, with carbon dioxide as the working medium inside; the dotted line represents the circuit diagram of the leakage flow path 40, with leaked carbon dioxide as the working medium inside; the dotted line represents the external normal temperature cooling fluid introduced, which is used to cool the carbon dioxide working medium.

[0032] In the embodiment of the present application, 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 connected to opposite ends of the drive shaft 15, respectively, and the motor 14 is located in the middle of the drive shaft 15. The turbine 13 converts 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, driving the impeller to rotate. This causes the turbine 13 to drive the drive shaft 15 to rotate together, causing the compressor 12 and motor 14 to rotate along with the drive shaft 15. The rotation of the compressor 12 compresses the supercritical carbon dioxide, while the rotation of the motor 14 outputs electrical energy, thus realizing the power generation function of the integrated component 10.

[0033] In specific implementation, the power generation system based on the supercritical carbon dioxide Brayton cycle of the present 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 the Brayton cycle, so that supercritical carbon dioxide can be used as the working fluid and the Brayton cycle can be used to complete energy conversion and achieve power generation effect.

[0034] The integrated component 10 of the main circulation system 100 further has a drain port 11 , through which the carbon dioxide working medium leaking 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, wherein the leakage flow path 40 is connected between the drain port 11 and the main circulation system 100, and the heat pump circulation loop 50 is connected to the overall loop of the main circulation system 100 through the drainage path 60. Since the temperature of the working fluid discharged from the drain port 11 of the integrated component 10 is relatively high, when the working fluid passes through the leakage flow path 40, it is first preliminarily cooled by the leakage cooling member 41 using an external cooling fluid. Subsequently, in the heat pump circulation loop 50, the working fluid injected from the main circulation system 100 will pass through the heat exchange component 80 to further cool the leaked carbon dioxide in the leakage flow path 40 to a liquid state, 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 increase the temperature, so that the leaked working fluid can be reinjected into the Brayton cycle at a higher temperature, thereby enabling the normal operation of the entire power generation system and ensuring the overall performance of the system.

[0035] 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 for the high-pressure wall of the integrated component 10, further meet the operating requirements of the integrated component 10 with higher speed and lower leakage, and enable the overall power generation system to have a wider range of operating conditions.

[0036] Furthermore, if the overall flow rate of the circulating working medium in the loop of the main circulation system 100 is high, the working medium in the loop of the main circulation system 100 can be further introduced into the internal volume of the heat pump circulation loop 50 through the drainage passage 60 to reduce the flow rate in the loop of the main circulation system 100; if the overall flow rate of the circulating working medium in the loop of the main circulation system 100 is low, the working medium in the internal volume of the heat pump circulation loop 50 can be introduced into the loop of the main circulation system 100 through the drainage passage 60 to increase the flow rate in the loop of the main circulation system 100. Therefore, the heat pump circulation loop 50 can not only adjust the temperature of the working medium in the leakage flow passage 40, but also regulate and buffer the flow rate of the circulating working medium in the loop of the main circulation system 100, so that the flow rate of the working medium in the loop of the main circulation system 100 reaches a range that meets the circulation requirements.

[0037] The embodiment of the present application is a power generation system based on a supercritical carbon dioxide Brayton cycle, wherein the inlet of the leakage flow path 40 is connected to the drain port 11 of the integrated component 10, and the outlet is connected to the heating path 20; the heat pump circulation loop 50 is connected to the cooling path 30 through the drainage path 60.

[0038] During specific implementation, the heat pump circulation loop 50 is connected to the cooling passage 30 through the drainage passage 60. The colder working medium in the cooling passage 30 can enter the heat pump circulation loop 50 through the drainage passage, while the working medium leaked from the leakage port 11 is in a relatively hot state when entering the leakage flow passage 40. After the working medium in the leakage flow passage 40 exchanges heat with the external cooling fluid passing through the leakage cooling part 41 and the working medium in the heat pump circulation loop 50 passing through the heat exchange component 80, the working medium in the leakage flow passage 40 can be cooled. After the cooled working medium is pressurized in the reinjection part 42, it can also exchange heat with the working medium in the heat pump circulation loop 50 passing through the heat exchange component 80 again to absorb heat and increase temperature, and finally be reinjected into the heating passage 20 through the leakage flow passage 40.

[0039] In an embodiment of the present application, a heating passage 20 is connected between the outlet of the compressor 12 and the inlet of the turbine 13, and a heater 21 is provided on the heating passage 20 for heating the working fluid flowing through the heating passage 20. A cooling passage 30 is connected between the outlet of the turbine 13 and the inlet of the compressor 12, and a first cooling member 31 and a second cooling member 32 are provided on the cooling passage 30 for cooling the working fluid flowing through the cooling passage 30.

[0040] In the Brayton cycle implemented by the main circulation system 100, the supercritical carbon dioxide heated by the heater 21 of the heating path 20 is in a high-temperature and high-pressure state. The high-temperature and high-pressure supercritical carbon dioxide enters from the inlet of the turbine 13. The turbine 13 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 path 30 is in a high-temperature and low-pressure state. After being cooled in sequence by the first cooling member 31 and the second cooling member 32 of the cooling path 30, the temperature of the supercritical carbon dioxide decreases and is converted into a low-temperature and low-pressure state. The supercritical carbon dioxide in the low-temperature and low-pressure state enters the compressor 12 from 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 path 20 is in a low-temperature and high-pressure state. Finally, it is converted into a high-temperature and high-pressure state after being heated by the heater 21 of the heating path 20, forming a complete Brayton cycle.

[0041] In the power generation system based on the supercritical carbon dioxide Brayton cycle according to an embodiment of the present application, a leakage flow cooling member 41 is provided on the leakage flow path 40 between the leakage port 11 and the heat exchange assembly 80. The leakage flow cooling member 41 is used to cool the working medium leaking from the leakage port 11. It should be noted that the leakage flow cooling member 41 exchanges heat with the leaking working medium in the leakage flow path 40 via a normal temperature cooling fluid introduced from the outside.

[0042] During specific implementation, a leakage cooling member 41 is provided on the leakage flow path 40 between the leakage port 11 and the heat exchange component 80, which can perform preliminary cooling on the working fluid leaking from the leakage port 11 to the leakage flow path 40. After preliminary cooling, the working fluid reaches the heat exchange component 80, and 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, so that the working fluid in the leakage flow path 40 can be cooled to a liquid state under low pressure, which facilitates liquid compression of the leakage flow path 40, thereby reducing the overall power consumption.

[0043] In the embodiment of the present application, a power generation system based on a supercritical carbon dioxide Brayton cycle is provided, wherein a return component 42 is provided on the leakage flow path 40 behind the leakage flow cooling component 41. The return component 42 is a pump body for pressurizing the working fluid in the leakage flow path 40 and injecting it back into the main circulation system 100.

[0044] In a specific implementation, after cooling, the working medium in the leakage flow path 40 is converted into liquid, and the re-injection component 42 can pump the liquid working medium back into the heating path 20 at a relatively low power.

[0045] The embodiment of the present application is a power generation system based on a supercritical carbon dioxide Brayton cycle, wherein the heat exchange component 80 includes a first heat exchange element 81 and a second heat exchange element 82, the first heat exchange element 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, the second connecting end 812 is connected to the leakage flow path 40, and the second connecting end 812 is arranged between the leakage flow cooling element 41 and the return injection element 42; the second heat exchange element 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, the fourth connecting end 822 is connected to the leakage flow path 40, and the fourth connecting end 822 is arranged after the return injection element 42.

[0046] In specific implementation, when heat exchange is carried out, the working fluid in the heat pump circulation loop 50 passes through the first connecting end 811 of the first heat exchange component 81 to cool the working fluid in the leakage flow path 40 passing through the second connecting end 812; the working fluid cooled through the second connecting end 812 can be pumped by the re-injection component 42 to the fourth connecting 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 pass through the third connecting end 821 to heat the working fluid in the fourth connecting end 822, so that the leaked working fluid can be reinjected into the heating path 20 at a higher temperature and directly participate in the main circulation.

[0047] The embodiment of the present application is a power generation system based on a supercritical carbon dioxide Brayton cycle, wherein the heat pump circulation component 70 includes a heat pump circulation cooling element 71, an expansion valve 72 and a heat pump circulation compressor 73. The heat pump circulation cooling element 71 and the expansion valve 72 are sequentially arranged 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 arranged on the heat pump circulation loop 50 from the first connecting end 811 to the third connecting end 821.

[0048] The embodiment of the present application is a power generation system based on a supercritical carbon dioxide Brayton cycle, wherein a first cooling member 31 and a second cooling member 32 are provided on the cooling passage 30, a first end of the drainage passage 60 is connected to the cooling passage 30 between the first cooling member 31 and the second cooling member 32 through a first three-way valve 61, and a second end of the drainage passage 60 is connected to the heat pump circulation loop 50 between the second heat exchange member 82 and the heat pump circulation compressor 73 through a second three-way valve 62.

[0049] During specific implementation, the working fluid cooled by the first cooling member 31 has its temperature reduced by a part, but is still in a relatively hot state. A part of the relatively hot working fluid enters the drainage passage 60 through the first three-way valve 61, and the other part enters the second cooling member 32 through the first three-way valve 61 to be cooled and continue the main circulation; part of the working fluid that enters the drainage passage 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.

[0050] When heat pump circulation is performed in the heat pump circulation loop 50, the heat pump circulation assembly 70 and the heat exchange assembly 80 work together in the heat pump circulation loop. Specifically, the second heat exchange element 82, the heat pump circulation cooling element 71, the expansion valve 72, the first heat exchange element 81, and the heat pump circulation compressor 73 are sequentially connected and arranged in the heat pump circulation loop 50, and the working medium circulates in the heat pump circulation loop 50 in the above order.

[0051] like Figure 3 As shown, Figure 3 The figure is a temperature entropy diagram of the working fluid and the external cooling fluid in each circuit and passage, wherein the dotted line is the saturation line of carbon dioxide, the solid line is the temperature entropy change of the working fluid in the heat pump circulation circuit 50 as it flows through each component, the single-dash line is the temperature change of the external normal-temperature cooling fluid, and the double-dash line is the temperature change of the working fluid in the leakage flow passage 40. After the hotter working fluid in the diversion passage 60 enters the heat pump circulation circuit 50 through the second three-way valve 62, as shown by the curve of the 2 to 2p segment of the solid line, the hotter working fluid enters the third connecting end 821 to release heat to heat the working fluid in the fourth connecting end 822. At this time, in the fourth connecting end 822, the temperature entropy change of the working fluid in the leakage flow passage 40 is as shown in FIG. Figure 3 As shown by the double-dotted line at the top; as shown by the solid line portion 2p to 3 curves, the working medium after the initial cooling is further cooled by the external normal temperature cooling fluid in the heat pump circulation cooling element 71, and the temperature change of the normal temperature cooling fluid is as shown Figure 3 As shown by the single dotted line in the middle; as shown by the curves of segments 3 to 4 of the solid line part, the working medium after being completely cooled is reduced in pressure through the expansion valve 72; as shown by the curves of segments 4 to 1 of the solid line part, the working medium after being reduced in pressure passes through the first connecting end 811 of the first heat exchange element 81, absorbs the heat of the working medium in the second connecting end 812, so as to cool the working medium in the leakage flow path 40 passing through the second connecting end 812. At this time, in the second connecting end 812, the temperature change of the working medium in the leakage flow path 40 is as shown in FIG. Figure 3 As shown by the double-dotted dashed line at the bottom of the figure; as shown by the solid line portion 1 to 2 of the curve, the heated working fluid reaches the heat pump cycle compressor 73 for pressure boosting. The pressurized working fluid ultimately reaches the second heat exchange element 82 and the heat pump cycle cooling element 71 for cooling, completing the cycle. Therefore, in the heat pump cycle loop 50, the working fluid of the main cycle is utilized for heat pump circulation. This cycle also achieves the sequential cooling and heating of the working fluid passing through the leakage flow path 40. 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 cycle at a higher temperature. This eliminates the need for a heating or cooling structure outside the power generation system, thus achieving energy conservation.

[0052] It should be noted that when heat pump circulation is carried out in the heat pump circulation loop 50, one end of the second three-way valve 62 used to connect the drainage path 60 is in a closed state to allow the heat pump circulation loop 50 to circulate itself. It will only be opened when the working fluid in the main circulation needs to be drained into the heat pump circulation loop 50 to achieve regulation and buffering of the working fluid in the main circulation.

[0053] In the power generation system based on the supercritical carbon dioxide Brayton cycle of the embodiment of the present application, a heater 21 is provided on the heating passage 20, and the leakage flow 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.

[0054] In specific implementation, the leakage flow path 40 is connected to the path between the heater 21 and the outlet of the compressor 12 through the third three-way valve 43. When the working fluid leaked 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 leaked in the leakage flow path 40 is cooled after passing through the leakage flow cooling member 41 and the heat exchange component 80, it can be compressed in liquid form using a pump, avoiding the leakage flow working fluid being reinjected using the compressor, resulting in overheating of the working fluid under large pressure ratio conditions.

[0055] The embodiment of the present application is a power generation system based on a supercritical carbon dioxide Brayton cycle, in which 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 provided on the side of the motor 14 close to the turbine 13.

[0056] The integrated component 10 also has a seal 17, a radial bearing 18 and a thrust bearing 19. Seals 17 and radial bearings 18 are provided between the compressor 12 and the motor 14, and between the turbine 13 and the motor 14. The thrust bearing 19 is provided between the seal 17 and the radial bearing 18 on one side of the compressor 12.

[0057] A through-gap 16 surrounds all components within the integrated component 10 and is provided around each component. Refrigerant leaking from the compressor 12 and turbine 13 can enter through the through-gap 16. Since the refrigerant at the turbine 13 is heated by the heating passage 20 and has a higher temperature, the refrigerant at the compressor 12 is at a lower temperature. Discharge port 11 is located on the side of the motor 14 near the turbine 13. The higher-temperature refrigerant at the turbine 13 does not pass through the motor 14 when flowing through the through-gap 16, thereby preventing the motor 14 from heating up. This ensures the normal operation of the motor 14. Meanwhile, the lower-temperature refrigerant at the compressor 12 cools the motor 14 when passing through the through-gap 16.

[0058] It should be noted that, in this document, relational terms such as first and second, etc., are used only to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply any actual relationship or order between these entities or operations. Moreover, the terms "comprises," "comprising," or any other variants thereof are intended to cover non-exclusive inclusion, so that a process, method, article, or device comprising a series of elements includes not only those elements, but also other elements not explicitly listed, or elements inherent to such process, method, article, or device. In the absence of further limitations, the elements defined by the phrase "comprising..." do not exclude the presence of other identical elements in the process, method, article, or device comprising the elements.

[0059] The above description is only a specific embodiment of the present application. Those skilled in the art will clearly understand that for the convenience and brevity of description, the specific working processes of the systems, modules and units described above can refer to the corresponding processes in the aforementioned method embodiments, and will not be repeated here. It should be understood that the scope of protection of the present application is not limited thereto. Any person skilled in the art can easily think of various equivalent modifications or replacements within the technical scope disclosed in the present application, and these modifications or replacements should be included in the scope of protection of the present application.

Claims

1. A power generation system based on a supercritical carbon dioxide Brayton cycle, characterized in that: The Brayton cycle is carried out using supercritical carbon dioxide as a working fluid. The power generation system comprises: A main circulation system (100) comprises 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 a Brayton cycle; The auxiliary circulation system (200) comprises a leakage flow path (40) and a heat pump circulation loop (50), wherein the leakage flow path (40) is connected between the leakage port (11) of the integrated component (10) and the overall loop of the main circulation system (100), the inlet of the leakage flow path (40) is connected to the leakage port (11) of the integrated component (10), and the outlet is connected to the heating path (20), the heat pump circulation loop (50) is connected to the cooling path (30) of the main circulation system (100) through a drainage path (60), and the leakage flow path (40) performs heat exchange with the heat pump circulation loop (50) through a heat exchange component (80).

2. The power generation system based on supercritical carbon dioxide Brayton cycle according to claim 1, characterized in that: A leakage flow cooling member (41) is provided on the leakage flow passage (40) between the leakage port (11) and the heat exchange assembly (80), and the leakage flow cooling member (41) is used to cool the working medium leaking from the leakage port (11).

3. The power generation system based on supercritical carbon dioxide Brayton cycle according to claim 2, characterized in that: A return component (42) is provided on the leakage flow passage (40) behind the leakage flow cooling component (41), and the return component (42) is used to pressurize and inject the working medium in the leakage flow passage (40) back into the main circulation system (100).

4. The power generation system based on supercritical carbon dioxide Brayton cycle according to claim 3, characterized in that: The heat exchange assembly (80) includes a first heat exchange element (81) and a second heat exchange element (82), wherein the first heat exchange element (81) includes a first connecting end (811) and a second connecting end (812), wherein 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 arranged between the leakage flow cooling element (41) and the return injection element (42); the second heat exchange element (82) includes a third connecting end (821) and a fourth connecting end (822), wherein 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 arranged after the return injection element (42).

5. The power generation system based on supercritical carbon dioxide Brayton cycle according to claim 4, characterized in that: A heat pump circulation component (70) is provided on the heat pump circulation loop (50), and the heat pump circulation component (70) includes a heat pump circulation cooling element (71), an expansion valve (72) and a heat pump circulation compressor (73). The heat pump circulation cooling element (71) and the expansion valve (72) are sequentially provided 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 provided on the heat pump circulation loop (50) from the first connecting end (811) to the third connecting end (821).

6. The power generation system based on supercritical carbon dioxide Brayton cycle according to claim 5, characterized in that: The cooling passage (30) is provided with a first cooling element (31) and a second cooling element (32); a first end of the drainage 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); a second end of the drainage 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).

7. The power generation system based on supercritical carbon dioxide Brayton cycle according to claim 1, characterized in that: The integrated component (10) includes a compressor (12), a turbine (13), a motor (14) and a transmission shaft (15), wherein the compressor (12), the turbine (13) and the motor (14) are coaxially connected via the transmission shaft (15), the compressor (12) and the turbine (13) are respectively connected to two ends of the transmission shaft (15), and the motor (14) is arranged in the middle of the transmission 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).

8. The power generation system based on supercritical carbon dioxide Brayton cycle according to claim 7, characterized in that: A heater (21) is provided on the heating passage (20), and the leakage flow passage (40) is connected to the passage between the heater (21) and the outlet of the compressor (12) via a third three-way valve (43).

9. The power generation system based on supercritical carbon dioxide Brayton cycle according to claim 7, characterized in that: The integrated component (10) further 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), and the drain port (11) is provided on a side of the motor (14) close to the turbine (13).

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