Power generation system based on supercritical carbon dioxide Brayton cycle

Abstract

The invention discloses a power generation system based on a supercritical carbon dioxide Brayton cycle, and the power generation system comprises a main circulation system which comprises an integrated part, a heating channel and a cooling channel, and the integrated part is connected between the heating channel and the cooling channel to form an overall loop of the Brayton cycle; the auxiliary circulation system comprises a leakage flow path and a heat pump circulation loop, the leakage flow path is connected between the drainage port of the integrated component and the main circulation system, the heat pump circulation loop is connected with an overall loop of the main circulation system through a drainage path, and the leakage flow path exchanges heat with the heat pump circulation loop through a heat exchange assembly. According to the Brayton cycle power generation system based on supercritical carbon dioxide, the working medium leaked from the integrated component cavity can be recycled, and the working medium is reinjected into the Brayton cycle with low compression power consumption and high 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 carbon dioxide Brayton cycle is usually used to convert heat energy into electrical energy. The supercritical carbon dioxide Brayton cycle uses high-temperature and high-pressure supercritical carbon dioxide to drive the turbine to rotate, thereby driving the motor to rotate and generate electricity, and drives the compressor to compress the supercritical carbon dioxide. The working fluid that has expanded and worked in the turbine enters the cooler to cool down, and then enters the compressor to be compressed. The pressurized working fluid enters the heater to absorb heat and heat up, and then enters the turbine again in a high-temperature and high-pressure state to work, realizing the Brayton cycle.

[0003] For integrated component machinery whose working fluid is supercritical carbon dioxide, due to the high pressure difference inside the integrated component machinery, 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 and the internal pressure to be too high, affecting the operation of the entire machinery and reducing the 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 a Brayton cycle is carried out using supercritical carbon dioxide as a working fluid, and the power generation system includes a main circulation system, including an integrated component, a heating passage and a cooling passage, wherein 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, wherein 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, and 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 discharge 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 flow cooling member is used to cool the working fluid leaking from the leakage port.

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

[0009] As above, a power generation system based on a 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 reinjection 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 reinjection element.

[0010] As above, a power generation system based on a supercritical carbon dioxide Brayton cycle, 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 above, the power generation system based on the supercritical carbon dioxide Brayton cycle, wherein the integrated components include a compressor, a turbine, a motor and a transmission shaft, the compressor, the turbine and the motor are coaxially connected through the transmission shaft, the compressor and the turbine are respectively connected to the two ends of the transmission shaft, and the motor is arranged in the middle of the transmission shaft; the heating passage is connected between the outlet of the compressor and the inlet of the turbine, and the cooling passage is connected between the outlet of the turbine and the inlet of the compressor.

[0013] In the power generation system based on the supercritical carbon dioxide Brayton cycle as described above, 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, in the power generation system based on the supercritical carbon dioxide Brayton cycle, there is also 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 arranged 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 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, so that supercritical carbon dioxide can be used as a working fluid, energy conversion can be completed through the Brayton cycle, and the power generation effect can be achieved.

[0016] The integrated component of the main circulation system also has a discharge port, and the carbon dioxide working fluid leaked during the operation of the integrated component can be discharged through the discharge port. The auxiliary circulation system includes a leakage flow path and a heat pump circulation loop, wherein the leakage flow path is connected between the discharge 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 discharge 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 injected back 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 injected back 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 solution 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 A schematic diagram of various loops and pathways in a power generation system based on a supercritical carbon dioxide Brayton cycle in an embodiment of the present application;

[0019] Figure 2 A 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 It is a temperature entropy diagram of the working fluid and the external cooling fluid in each circuit and passage of 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. Drainage 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 only 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 parts for heat and work conversion in the cycle, and their performance is an important factor affecting the cycle performance.

[0026] In the actual operation of the supercritical carbon dioxide Brayton cycle system, in order to improve the compactness and simplicity of the system, reduce the system's footprint and balance the axial force, the compressor and turbine are usually arranged on both sides of the same shaft, and the motor is arranged in the middle of the shaft to form an overall integrated component mechanical structure. This integrated component mechanical structure is usually referred to as TAC (Turbine-Alternator-Compressor). The integrated component uses the work generated by the rotation of the turbine blades to drive the compressor to rotate together to compress the supercritical carbon dioxide working fluid, and the excess work is converted into electrical energy in the motor, thereby realizing thermoelectric conversion.

[0027] For integrated components machinery with supercritical carbon dioxide as the working fluid, the volume size of the integrated components machinery will be relatively reduced due to the high density of the working fluid, but the internal gap size cannot be greatly reduced due to the limitation of processing technology. Therefore, the gap of the integrated components machinery with supercritical carbon dioxide as the working fluid is larger than that of conventional turbomachinery using air and water as the working fluid, and the leakage will be more serious. In the integrated components machinery, the carbon dioxide leaked from the compressor and turbine will flow into the chamber where the motor is located through seals, bearings and other components. If this part of carbon dioxide is not discharged in time, the pressure inside the chamber will become higher and higher, and the high-pressure and high-density carbon dioxide will rotate together with the high-speed rotation of the rotor components such as the motor and bearings in the gap between the rotor and the stator, generating a large amount of friction loss. This part of the friction loss is called wind resistance loss, which is proportional to the density of the working fluid and the cube of the rotor speed. The greater the chamber pressure, the greater the wind resistance loss caused by the rotation of the rotor components, and the greater the heat load, which not only puts the components in the chamber at risk of over-temperature failure, but also reduces the system performance.

[0028] At present, when solving the problem of internal leakage and windage loss of integrated component machinery, a pump is mainly used to extract the leakage flow in the integrated component machinery, cool and pressurize the leakage flow, and then inject it back into the main cycle, that is, the Brayton cycle where the integrated component machinery is located. This can not only recover the leakage flow, but also make the pressure in the chamber lower, meeting the operation requirements of higher speed and lower leakage of the integrated component. During the extraction process, if the pressure in the chamber is relatively high, the cooling system at room temperature can liquefy the extracted leaked carbon dioxide, so that it can be injected back only by using a pump. However, if the chamber pressure is low, the leaked carbon dioxide is still in a gaseous state after cooling. At this time, a compressor is required for compression, which will not only increase the power consumption, but also face the problem of too high temperature of the working fluid at the compressor outlet when the pressure ratio is too large, resulting in the compressor being unable to work normally, so the leaked carbon dioxide needs to be further cooled. In addition, an increase in speed or a decrease in leakage will cause the temperature of the internal components of the integrated component machinery to rise. At this time, if the chamber pressure can be further reduced, the windage loss can be greatly reduced, thereby reducing the internal temperature. Therefore, the present application proposes a power generation system based on a supercritical carbon dioxide Brayton cycle, which is capable of extracting 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, 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 the components with higher speeds and lower leakage.

[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 a 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, 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; an auxiliary circulation system 200, including a leakage flow passage 40 and a heat pump circulation loop 50, wherein 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, and the heat pump circulation loop 50 is connected to the overall loop of the main circulation system 100 via a drainage passage 60, and the leakage flow passage 40 performs heat exchange with the heat pump circulation loop 50 via a 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 It is a schematic diagram of the various circuits and pathways in the power generation system. Figure 2 Figure 1 is 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 in the main circulation system 100 and the heat pump circulation loop 50, 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 transmission shaft 15. The compressor 12, the turbine 13 and the motor 14 are coaxially connected through the transmission shaft 15. The compressor 12 and the turbine 13 are respectively connected to the two ends of the transmission shaft 15, and the motor 14 is arranged in the middle of the transmission 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, so that the turbine 13 can drive the transmission shaft 15 to rotate together, so that the compressor 12 and the motor 14 rotate with the transmission 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.

[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 a working fluid and energy conversion can be completed by the Brayton cycle to achieve a power generation effect.

[0034] The integrated component 10 of the main circulation system 100 also has a leakage port 11 , through which the carbon dioxide working medium leaking during the operation of the integrated component 10 can be discharged. 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 leakage 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 leakage port 11 of the integrated component 10 is relatively high, when the working fluid passes through the leakage flow path 40, it is firstly cooled by an external cooling fluid through the leakage flow cooling member 41. Subsequently, in the heat pump circulation loop 50, the working fluid injected from 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 increase the temperature, so that the leaked working fluid can be reinjected into the Brayton cycle at a higher temperature, thereby enabling the overall power generation system to operate normally 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 make the chamber of the integrated component 10 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] Moreover, if the overall flow rate of the circulating medium in the loop of the main circulation system 100 is high, the 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 medium in the loop of the main circulation system 100 is low, the 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 medium in the leakage flow passage 40, but also regulate and buffer the flow rate of the circulating medium in the loop of the main circulation system 100, so that the flow rate of the 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 discharge 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] In specific implementation, the heat pump circulation loop 50 is connected to the cooling passage 30 through the drainage passage 60. The colder working fluid in the cooling passage 30 can enter the heat pump circulation loop 50 through the drainage passage, while the working fluid leaked from the leakage port 11 is in a relatively hot state when entering the leakage flow passage 40. The working fluid in the leakage flow passage 40 can be cooled after heat exchange with the external cooling fluid passing through the leakage cooling member 41 and the working fluid in the heat pump circulation loop 50 passing through the heat exchange component 80. The cooled working fluid can be pressurized in the reinjection member 42 and can again exchange heat with the working fluid in the heat pump circulation loop 50 passing through the heat exchange component 80 to absorb heat and rise in 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 passage 20 is in a high temperature and high pressure state, and 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, and 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 in sequence by the first cooling member 31 and the second cooling member 32 of the cooling passage 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, and 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, and is finally converted into a high temperature and high pressure state after being heated by the heater 21 of the heating passage 20, forming a complete Brayton cycle.

[0041] In the power generation system based on the supercritical carbon dioxide Brayton cycle of the 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, and 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 performs heat exchange with the leaking working medium in the leakage flow path 40 through the normal temperature cooling fluid introduced from the outside.

[0042] In 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 preliminarily cool the working fluid leaking from the leakage port 11 to the leakage flow path 40. The working fluid after preliminarily cooling 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 the liquid compression of the leakage flow path 40, thereby reducing the overall power consumption.

[0043] The embodiment of the present application is a power generation system based on a supercritical carbon dioxide Brayton cycle, in which a re-injection component 42 is provided on the leakage flow path 40 behind the leakage flow cooling component 41, and the re-injection 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 reinjection 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 reinjection element 42.

[0046] In specific implementation, when heat exchange is performed, the working fluid in the heat pump circulation loop 50 cools the working fluid in the leakage flow path 40 through the second connecting end 812 through the first connecting end 811 of the first heat exchange component 81; the working fluid cooled through the second connecting end 812 can be pumped by the reinjection 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 heat the working fluid in the fourth connecting end 822 through the third connecting end 821, 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 a 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 a 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 after being 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 carry out the heat pump circulation.

[0050] When the heat pump circulation is performed in the heat pump circulation loop 50, the heat pump circulation component 70 and the heat exchange component 80 act together on the heat pump circulation loop. Specifically, the second heat exchange component 82, the heat pump circulation cooling component 71, the expansion valve 72, the first heat exchange component 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 is a temperature entropy diagram of the working fluid in each circuit and passage and the external cooling fluid, 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 flowing through each component, the single-point dashed line is the temperature change of the external normal temperature cooling fluid, and the double-point dashed line is the temperature change of the working fluid in the leakage flow passage 40. After the hotter working fluid in the drainage passage 60 enters the heat pump circulation circuit 50 through the second three-way valve 62, as shown in the 2 to 2p segment curve of the solid line part, 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 fluid 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 the solid line section 3 to 4, the completely cooled working medium is depressurized by the expansion valve 72; as shown by the curves of the solid line section 4 to 1, the depressurized working medium passes through the first connecting end 811 of the first heat exchange element 81, absorbs the working medium heat in the second connecting end 812, so that the working medium in the leakage flow path 40 passing through the second connecting end 812 is cooled. 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 line at the bottom; as shown by the curves of the solid line part 1 to 2, the heated working fluid reaches the heat pump circulation compressor 73 for boosting, and the boosted working fluid finally reaches the second heat exchange element 82 and the heat pump circulation cooling element 71 for cooling to complete the complete cycle. Therefore, in the heat pump circulation loop 50, the working fluid of the main cycle is used for heat pump circulation, and the working fluid passing through the leakage flow path 40 is successively cooled and heated through this circulation process, so that the working fluid in the leakage flow path 40 can not only be compressed in liquid form, but also be injected back into the main cycle at a higher temperature, without the need for a heating or cooling structure outside the power generation system, which plays a role in energy saving.

[0052] It should be noted that when the 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 passage 60 is in a closed state to allow the heat pump circulation loop 50 to circulate itself. It will be opened only 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] The power generation system based on the supercritical carbon dioxide Brayton cycle of the embodiment of the present application, wherein 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 leaked working fluid 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 leaked working fluid 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, thereby avoiding the leakage flow working fluid being reinjected using the compressor, resulting in overtemperature of the working fluid under a large pressure ratio.

[0055] The embodiment of the present application is a power generation system based on a supercritical carbon dioxide Brayton cycle, wherein 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, and the drain port 11 is arranged 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 inside. The seal 17 and the radial bearing 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] The gap 16 is arranged around all the parts inside the integrated component 10 and is arranged on the peripheral side of each part. The working fluid leaked from the compressor 12 and the turbine 13 can enter the gap 16. Since the working fluid at the turbine 13 is heated by the heating passage 20, the temperature is relatively high, while the working fluid at the compressor 12 is relatively low. The drain port 11 is arranged on the side of the motor 14 close to the turbine 13. When the working fluid at the turbine 13 with a relatively high temperature flows through the gap 16, it will not pass through the motor 14, and thus will not heat up the motor 14, thereby ensuring the normal operation of the motor 14. The working fluid at the compressor 12 with a relatively low temperature can cool the motor 14 when passing through the motor 14.

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

[0059] The above is only a specific implementation of the present application. Those skilled in the art can clearly understand that for the convenience and simplicity 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 protection scope of the present application is not limited to this. Any technician familiar with the technical field can easily think of various equivalent modifications or replacements within the technical scope disclosed in this application, and these modifications or replacements should be included in the protection scope of this application.

Claims

1. A power generation system based on supercritical carbon dioxide Brayton cycle, characterized in that: The Brayton cycle is carried out using supercritical carbon dioxide as a working fluid, and 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 passage (40) and a heat pump circulation loop (50), wherein the leakage flow passage (40) is connected between the leakage 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) via a drainage passage (60), and the leakage flow passage (40) performs heat exchange with the heat pump circulation loop (50) via a heat exchange component (80).

2. The power generation system based on supercritical carbon dioxide Brayton cycle according to claim 1, characterized in that: The inlet of the leakage flow passage (40) is connected to the drain port (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) via the drainage passage (60).

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

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

5. The power generation system based on supercritical carbon dioxide Brayton cycle according to claim 4, characterized in that: The heat exchange component (80) comprises a first heat exchange element (81) and a second heat exchange element (82), wherein the first heat exchange element (81) comprises 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) comprises 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).

6. The power generation system based on supercritical carbon dioxide Brayton cycle according to claim 5, 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 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).

7. The power generation system based on supercritical carbon dioxide Brayton cycle according to claim 6, characterized in that: The cooling passage (30) is provided with a first cooling element (31) and a second cooling element (32); the 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) via a first three-way valve (61); the 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) via a second three-way valve (62).

8. The power generation system based on supercritical carbon dioxide Brayton cycle according to claim 1 or 2, characterized in that: The integrated component (10) comprises a compressor (12), a turbine (13), a motor (14) and a transmission shaft (15); 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).

9. The power generation system based on supercritical carbon dioxide Brayton cycle according to claim 8, characterized in that: The heating passage (20) is provided with a heater (21), 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).

10. The power generation system based on supercritical carbon dioxide Brayton cycle according to claim 8, characterized in that: 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), and the drain port (11) is arranged on a side of the motor (14) close to the turbine (13).

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