Turbine self-cooling combined cycle system for supercritical carbon dioxide Brayton cycle

Abstract

The invention provides a turbine self-cooling combined cycle system for a supercritical carbon dioxide Brayton cycle. The turbine self-cooling combined cycle system comprises a Brayton cycle system, a heat pump heat supply system and a turbine cooling branch. Wherein the Brayton cycle system is constructed to perform Brayton cycle by taking supercritical carbon dioxide as first working medium gas, output mechanical energy through the turbine assembly and output electric energy through the energy conversion assembly; the heat pump heat supply system is configured to take carbon dioxide as second working medium gas to output heat at the heat output end; the turbine cooling branch is configured to be connected with the Brayton cycle system and the heat pump heat supply system, the turbine cooling branch is configured to lead out at least part of first working medium gas as exchange gas and convey the exchange gas to the heat pump heat supply system, and at least part of second working medium gas as cooling gas and convey the cooling gas to the turbine assembly; therefore, self-cooling of the turbine assembly is achieved, and the first working medium gas is supplemented to the Brayton cycle system.

Description

Technical Field

[0001] The present disclosure relates to the technical field of supercritical carbon dioxide Brayton cycle power generation and the technical field of heat pumps, and in particular to a turbine self-cooling combined cycle system for a supercritical carbon dioxide Brayton cycle. Background Art

[0002] With the rapid development of society, the contradiction between energy and environment has become increasingly prominent. Exploring efficient and clean energy conversion methods has become one of the main directions of development in the domestic energy field. Supercritical carbon dioxide (sCO2) Brayton cycle, as a flexible, efficient and suitable power generation method for small and medium-sized power generation, has shown great application potential in power generation fields such as solar energy, nuclear energy, and waste heat utilization. In the research of related technologies, it was found that when the heat source temperature is in the range of 550-720℃, the thermoelectric conversion efficiency of sCO2 power generation can reach 40-50%, which can be increased by 3-5 percentage points compared with the steam Rankine cycle; in addition, a notable feature of the sCO2 power generation method is that the overall system volume is compact and highly flexible. The volume of the main engine is 1 / 20-1 / 30 of that of the steam turbine, and the volume of the heat exchanger is 1 / 7-1 / 15 of that of the traditional shell and tube heat exchanger, which can be better used in power generation scenarios such as ships and solar thermal power stations; at the same time, the critical temperature and pressure of CO2 (31℃, 7.38MPa) are much lower than the critical point of water, and it is easy to reach a supercritical state, which is conducive to engineering applications.

[0003] In the process of the Brayton cycle system (sCO2 cycle system), the high-temperature turbine, as the direct energy output device of the system, converts the thermal energy of high-temperature and high-pressure sCO2 into mechanical energy for the operation of the generator. It is one of the key equipment for the operation of the system, and its performance directly affects the efficiency of the system. In order to maintain the efficient operation of the power generation system, the heat source temperature of the heater generally exceeds 550°C, causing the high-temperature turbine flow components to work in a high-temperature and high-pressure state for a long time, which puts high demands on the shaft end seal design of the turbine.

[0004] At present, due to the large leakage of labyrinth seals, it is difficult to meet the sealing requirements, and most units use dry gas seals as the shaft end seals of sCO2 turbine machinery. However, the dry gas seal is limited by the material, sealing structure, etc. The temperature of the working environment should not be too high. Cooling measures must be taken between the seal and the turbine to ensure thermal safety and prevent the dry gas seal from being damaged due to over-temperature operation. In related technologies, the cooling gas of the dry gas seal is mainly extracted within the system, which increases the compression power consumption of the main compressor on the one hand, and also requires heat to be absorbed from the system, resulting in reduced system efficiency.

[0005] Therefore, in the Brayton cycle system, designing a reasonable cooling method for the high-temperature turbine under dry gas seal has far-reaching practical significance. Summary of the invention

[0006] In view of this, in order to solve at least one technical problem in the related art and other aspects, the present disclosure proposes a combined cycle system for turbine self-cooling of supercritical carbon dioxide Brayton cycle, including a Brayton cycle system, a heat pump heating system and a turbine cooling branch. Among them, the Brayton cycle system is configured to use supercritical carbon dioxide as the first working gas to perform a Brayton cycle, and output mechanical energy through a turbine component, and output electrical energy through an energy conversion component; the heat pump heating system is configured to use carbon dioxide as the second working gas to output heat at the heat output end; the turbine cooling branch is configured to connect the Brayton cycle system and the heat pump heating system, and the turbine cooling branch is configured to lead out at least part of the first working gas as exchange gas, and transport it to the heat pump heating system to participate in the heating of the heat pump heating system, and transport at least part of the second working gas as cooling gas to the turbine component to achieve self-cooling and cooling of the turbine component, and replenish the first working gas to the Brayton cycle system.

[0007] According to an embodiment of the present disclosure, the turbine cooling branch includes a first branch and a second branch. The inlet of the first branch is connected to the working rear section of the Brayton cycle system, and the outlet of the first branch is connected to the working front section of the heat pump heating system. The first branch is suitable for drawing out at least part of the first working fluid gas after working in the Brayton cycle system as exchange gas, and transporting it to the heat pump heating system to mix with the second working fluid gas; the second branch is suitable for drawing out at least part of the second working fluid gas in the heat pump heating system as cooling gas, and transporting it to the turbine assembly to cool the turbine assembly. The flow rates of the exchange gas and the cooling gas are the same.

[0008] According to an embodiment of the present disclosure, the first branch includes a first pressure regulating component and a first flow regulating component. The first pressure regulating component is used to adjust the pressure of the exchange gas so that the exchange gas enters the heat pump heating system through the first branch; the first flow regulating component is used to adjust the flow of the exchange gas. The second branch includes a second flow regulating component, and the second flow regulating component is used to adjust the flow of the cooling gas so that the flow of the cooling gas is the same as the flow of the exchange gas.

[0009] According to an embodiment of the present disclosure, the flow rate of the exchange air and the cooling air is 0.15-0.4 kg / s.

[0010] According to the embodiments of the present disclosure, the pressure of the exchange gas is 7.5-8.5 MPa, and the temperature of the exchange gas is 33-35°C; the pressure of the cooling gas is 9-18 MPa, and the temperature of the cooling gas is 90-120°C.

[0011] According to an embodiment of the present disclosure, the Brayton cycle system includes a first compressor, a heater, a turbine assembly, an energy conversion assembly, and a cooler. Among them, the first compressor is suitable for pressurizing the first working fluid gas; the heater is configured to receive heat from outside the combined cycle system and heat the pressurized first working fluid gas; the turbine assembly is suitable for receiving the heated and pressurized first working fluid gas, accommodating the heated and pressurized first working fluid gas to expand and output mechanical energy; the energy conversion assembly is suitable for receiving mechanical energy, converting and outputting electrical energy, the inlet of the cooler is connected to the outlet of the turbine assembly, and is suitable for receiving the first working fluid gas after work and cooling it down, and the outlet of the cooler is connected to the inlet of the first compressor, so that the cooled first working fluid gas returns to the first compressor for the next cycle.

[0012] According to an embodiment of the present disclosure, the Brayton cycle system further comprises a first regenerator. The first regenerator is respectively connected to the first compressor and the heater, as well as the turbine assembly and the cooler, and is suitable for recovering waste heat of the Brayton cycle system and performing heat exchange with the first working fluid gas.

[0013] According to an embodiment of the present disclosure, a turbine assembly includes an impeller, a main shaft, and a shaft end. The impeller is suitable for converting thermal energy into mechanical energy; the main shaft is suitable for supporting the impeller and transmitting rotational torque; the shaft end is configured to prevent leakage of the first working fluid gas through a dry gas seal. A cooling gas inlet is provided at a position of the main shaft near the shaft end, which is suitable for receiving cooling gas and cooling the dry gas seal; a cooling gas outlet is provided at a position of the main shaft near the impeller, which is suitable for leading out cooling gas and merging with the first working fluid gas.

[0014] According to an embodiment of the present disclosure, a heat pump heating system includes an evaporator, a second compressor, a heat output end, and a throttle valve. The evaporator is configured to receive heat from outside the combined system and heat the second working fluid gas; the second compressor is adapted to pressurize the heated second working fluid gas; the heat output end is adapted to receive the heated and pressurized second working fluid gas and output heat; the inlet of the throttle valve is connected to the outlet of the heat output end, and the outlet of the throttle valve is connected to the inlet of the evaporator, and is adapted to reduce the pressure of the second working fluid gas.

[0015] According to an embodiment of the present disclosure, the heat pump heating system further includes a second regenerator. The second regenerator is respectively connected to the evaporator and the second compressor, as well as the heat output end and the throttle valve, and is suitable for recovering waste heat of the heat pump heating system and performing heat exchange with the second working fluid gas.

[0016] According to the embodiments of the present disclosure, the present disclosure proposes a combined cycle system of turbine self-cooling coupled with a Brayton cycle system and a heat pump heating system. The combination of the two realizes the recycling of the working gas, and uses part of the working gas as cooling gas to cool the turbine in the Brayton cycle system, thereby avoiding damage to the dry gas seal by high temperature and ensuring the safety of the dry gas seal. The Brayton cycle system is combined with the heat pump heating system to reduce the power consumption of the compression of the cooling gas involved in the turbine cooling, while reducing the energy loss of adjusting the cooling gas temperature, and improving the efficiency of the supercritical carbon dioxide Brayton cycle. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 is a schematic diagram of the principle of a combined cycle system in an embodiment of the present disclosure;

[0018] Figure 2 It is a partial cross-sectional schematic diagram of a turbine assembly of a combined cycle system in an embodiment of the present disclosure.

[0019] In the above drawings, the specific symbols have the following meanings:

[0020] M001-motor;

[0021] C001-first compressor;

[0022] H001-first regenerator;

[0023] H002-heater;

[0024] TU001-turbine assembly;

[0025] T001-impeller;

[0026] T002-spindle;

[0027] T003- shaft end;

[0028] G001-Energy conversion components;

[0029] H003-Cooler;

[0030] C002-second compressor;

[0031] H004-heat output terminal;

[0032] H005-evaporator;

[0033] H006-second regenerator;

[0034] YJ001-throttle valve;

[0035] X001-first branch;

[0036] X002-Second branch. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solution and advantages of the present disclosure more clearly understood, the present disclosure is further described in detail below in combination with specific embodiments and with reference to the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present disclosure, not all of them.

[0038] The terms used herein are only for describing specific embodiments and are not intended to limit the present disclosure. The terms "comprise", "include", etc. used herein indicate the existence of the features, steps, operations and / or components, but do not exclude the existence or addition of one or more other features, steps, operations or components.

[0039] In the present disclosure, unless otherwise clearly specified and limited, the terms "installed", "connected", "connected", "fixed" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or can communicate with each other; it can be a direct connection, or it can be indirectly connected through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements. For ordinary technicians in this field, the specific meanings of the above terms in the present disclosure can be understood according to specific circumstances.

[0040] In the description of the present disclosure, it is necessary to understand that the terms "longitudinal", "length", "circumferential", "front", "rear", "left", "right", "top", "bottom", "inside", "outside", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings, and are only for the convenience of describing the present disclosure and simplifying the description, and do not indicate or imply that the subsystem or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present disclosure.

[0041] Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or configurations will be omitted when they may cause confusion in the understanding of the present disclosure. The shapes, sizes, and positional relationships of the components in the drawings do not reflect the actual size, proportion, and actual positional relationship. In addition, in the present disclosure, any reference symbol between brackets should not be constructed as a limitation to the present disclosure.

[0042] Similarly, in order to simplify the present disclosure and help understand one or more of the various disclosed aspects, in the above description of the exemplary embodiments of the present disclosure, the various features of the present disclosure are sometimes grouped together into a single embodiment, figure, or description thereof. The description with reference to the terms "one embodiment", "some embodiments", "example", "specific example", or "some examples" and the like means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present disclosure. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0043] In addition, the terms "first", "second", etc. are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the feature. In the description of the present disclosure, the meaning of "plurality" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined.

[0044] The Brayton cycle system is the direct energy output device of the sCO2 cycle system, and the turbine components have a high operating temperature. To ensure the safe operation of the dry gas seal, cooling measures must be taken between the seal and the turbine to ensure thermal safety and prevent the dry gas seal from being damaged due to over-temperature operation.

[0045] In the related technology, most of the units that have been built draw air from the system when performing turbine cooling. For example, a regulating valve is used to adjust the cooling air flow rate, which can maintain the temperature of the dry gas seal component and prevent the dry gas seal from being damaged due to over-temperature operation. However, in this way, the cooling air participating in turbine cooling still needs to be pressurized by the main compressor, and the system needs to provide heat to it so that its temperature and pressure meet the requirements for participating in cooling, so the system performance is not greatly improved.

[0046] During the implementation of the present disclosure, it was found that in order to ensure the thermal safety of the dry gas seal in the Brayton cycle system (sCO2 cycle system), a system of combined circulation of the Brayton cycle system and the heat pump heating system can be designed, and the CO2 in the CO2 heat pump system can be used as cooling gas by using a turbine cooling branch, and introduced into the sCO2 system to participate in turbine cooling; at the same time, the CO2 in the sCO2 cycle system can also be introduced into the CO2 heat pump system through the turbine cooling branch to achieve continuous and stable operation of the system.

[0047] In the present disclosure, the term "turbine" means: a turbine assembly (turbine machine), which is a machine that converts energy contained in a fluid medium into mechanical energy. The specific form can be a compressor, a steam turbine, a turbine, a flue gas turbine, and an expander. The working fluid of the turbine assembly involved in the present disclosure is carbon dioxide (CO2) and supercritical carbon dioxide (sCO2).

[0048] Figure 1 It is a schematic diagram of the principle of the combined cycle system in the embodiment of the present disclosure.

[0049] In one aspect of the present disclosure, a combined cycle system for turbine self-cooling of a supercritical carbon dioxide Brayton cycle is proposed, comprising a Brayton cycle system, a heat pump heating system, and a turbine cooling branch. The Brayton cycle system is configured to use supercritical carbon dioxide as a first working gas to perform a Brayton cycle, and output mechanical energy through a turbine component TU001, and output electrical energy through an energy conversion component G001; the heat pump heating system is configured to use carbon dioxide as a second working gas to output heat at a heat output end H004; the turbine cooling branch is configured to connect the Brayton cycle system and the heat pump heating system, the turbine cooling branch is configured to draw out at least part of the first working gas as an exchange gas, and transport it to the heat pump heating system to participate in the heating of the heat pump heating system, and transport at least part of the second working gas as a cooling gas to the turbine component TU001, so as to achieve self-cooling and cooling of the turbine component TU001, and replenish the first working gas to the Brayton cycle system.

[0050] According to the embodiments of the present disclosure, the present disclosure proposes a combined cycle system of turbine self-cooling coupled with a Brayton cycle system and a heat pump heating system. The combination of the two realizes the recycling of the working gas, and uses part of the working gas as cooling gas to cool the turbine in the Brayton cycle system, thereby avoiding damage to the dry gas seal by high temperature and ensuring the safety of the dry gas seal. The Brayton cycle system is combined with the heat pump heating system to reduce the power consumption of the compression of the cooling gas involved in the turbine cooling, while reducing the energy loss of adjusting the cooling gas temperature, and improving the efficiency of the supercritical carbon dioxide Brayton cycle.

[0051] According to an embodiment of the present disclosure, the turbine cooling branch includes a first branch X001 and a second branch X002. The inlet of the first branch X001 is connected to the working rear section of the Brayton cycle system, and the outlet of the first branch X001 is connected to the working front section of the heat pump heating system. The first branch X001 is suitable for drawing out at least part of the first working fluid gas after working in the Brayton cycle system as exchange gas, and transporting it to the heat pump heating system to mix with the second working fluid gas; the second branch X002 is suitable for drawing out at least part of the second working fluid gas in the heat pump heating system as cooling gas, and transporting it to the turbine component TU001 to cool the turbine component TU001. The flow rates of the exchange gas and the cooling gas are the same.

[0052] According to an embodiment of the present disclosure, the Brayton cycle system includes a first compressor C001, a heater H002, a turbine assembly TU001, an energy conversion assembly G001 and a cooler H003. Among them, the first compressor C001 is suitable for pressurizing the first working fluid gas; the heater H002 is configured to receive heat outside the combined cycle system and heat the pressurized first working fluid gas; the turbine assembly TU001 is suitable for receiving the heated and pressurized first working fluid gas, accommodating the heated and pressurized first working fluid gas to expand and output mechanical energy; the energy conversion assembly is suitable for receiving mechanical energy, converting and outputting electrical energy, the inlet of the cooler H003 is connected to the outlet of the turbine assembly TU001, and is suitable for receiving the first working fluid gas after work and cooling it down, and the outlet of the cooler H003 is connected to the inlet of the first compressor C001, so that the cooled first working fluid gas returns to the first compressor C001 for the next cycle.

[0053] In some specific embodiments, the turbine assembly TU001 may be in the form of an expander, and the energy conversion device G001 may be in the form of a generator. The form of the first compressor C001 and the turbine assembly TU001 may be adjusted according to demand, such as using multi-stage compression and multi-stage expansion, or using a TAC structure according to demand.

[0054] According to an embodiment of the present disclosure, the heat pump heating system includes an evaporator H005, a second compressor C002, a heat output terminal H004 and a throttle valve YJ001. The evaporator H005 is configured to receive heat from outside the combined system and heat the second working fluid gas; the second compressor C002 is suitable for pressurizing the heated second working fluid gas; the heat output terminal H004 is suitable for receiving the heated and pressurized second working fluid gas and outputting heat; the inlet of the throttle valve YJ001 is connected to the outlet of the heat output terminal H004, and the outlet of the throttle valve YJ001 is connected to the inlet of the evaporator H005, which is suitable for reducing the pressure of the second working fluid gas.

[0055] In some specific embodiments, the second compressor C002 may also be a supercritical carbon dioxide compressor, that is, the pressure of the second working fluid gas in the heat pump heating system is maintained above the critical pressure.

[0056] In some specific embodiments, the first branch X001 introduces the CO2 gas after work cooling in the Brayton cycle system to the outlet of the throttle valve YJ001 of the heat pump heating cycle system, and can also be introduced to the cold end inlet of the regenerator H006, the cold end outlet of the regenerator H006, etc. according to the state of the working gas. That is, the outlet of the first branch X001 needs to be ensured to be in the low-pressure pipe section of the heat pump heating system.

[0057] In some specific embodiments, the second branch X002 introduces the pressurized and heated CO2 in the heat pump heating system into the Brayton cycle system as cooling gas for the turbine assembly TU001. Specifically, the inlet of the second branch X002 can be the outlet of the second compressor C002, or it can be drawn from the outlet of the heat output end H004 according to the state of the second working fluid gas in the heat pump heating system. That is, the inlet of the second branch X002 needs to ensure that the temperature and pressure of CO2 meet the requirements of the temperature and pressure of the cooling gas. More specifically, the temperature requirement of the cooling gas is 90-120°C, and the pressure requirement of the cooling gas is 9-18MPa.

[0058] According to an embodiment of the present disclosure, the first branch X001 includes a first pressure regulating component and a first flow regulating component. The first pressure regulating component is suitable for adjusting the pressure of the exchange gas so that the exchange gas enters the heat pump heating system through the first branch X001; the first flow regulating component is suitable for adjusting the flow of the exchange gas. The second branch X002 includes a second flow regulating component, which is suitable for adjusting the flow of the cooling gas so that the flow of the cooling gas is the same as the flow of the exchange gas.

[0059] According to an embodiment of the present disclosure, the flow rate of the exchange air and the cooling air is 0.15-0.4 kg / s.

[0060] According to the embodiment of the present disclosure, the exchange air and the cooling air are connected to the Brayton cycle system and the heat pump heating system through the first branch X001 and the second branch X002 respectively. In order to ensure the stable operation of the two, the flow rates of the exchange air and the cooling air must be consistent. Specifically, the flow rate of the exchange air depends on the flow rate of the cooling air required by the turbine component during the actual operation of the combined cycle system.

[0061] According to the embodiments of the present disclosure, the pressure of the exchange gas is 7.5-8.5 MPa, and the temperature of the exchange gas is 33-35°C; the pressure of the cooling gas is 9-18 MPa, and the temperature of the cooling gas is 90-120°C.

[0062] According to an embodiment of the present disclosure, the Brayton cycle system further includes a first regenerator H001. The first regenerator H001 is connected to the first compressor C001 and the heater H002, as well as the turbine assembly TU001 and the cooler H003, and is suitable for recovering waste heat of the Brayton cycle system and performing heat exchange with the first working fluid gas.

[0063] In some specific embodiments, the Brayton cycle system further includes a motor M001 for driving the first compressor C001.

[0064] According to an embodiment of the present disclosure, the cycle process of the Brayton cycle system is as follows: the sCO2 working fluid near the critical point enters the first compressor C001 to increase the pressure, enters the first regenerator H001 to absorb heat, and is heated to high-temperature and high-pressure sCO2 in the heater H002; then, the high-temperature and high-pressure SCO2 enters the turbine component TU001 to expand and drive the turbine to do work, converting thermal energy into mechanical energy, driving the energy conversion component G001 to work, and the temperature and pressure of sCO2 decrease; finally, since the temperature of sCO2 after doing work is relatively high, it enters the first regenerator H001 to recover part of the heat energy, and then enters the cooler H003 to cool to the required temperature at the inlet of the first compressor C001, and re-enters the first compressor C001 to complete a cycle.

[0065] Figure 2 It is a partial cross-sectional schematic diagram of a turbine assembly of a combined cycle system in an embodiment of the present disclosure.

[0066] According to an embodiment of the present disclosure, the turbine assembly TU001 includes an impeller T001, a main shaft T002, and a shaft end T003. The impeller T001 is suitable for converting thermal energy into mechanical energy; the main shaft T002 is suitable for supporting the impeller and transmitting rotational torque; the shaft end T003 is configured to prevent leakage of the first working fluid gas through a dry gas seal. Among them, the main shaft T002 is provided with a cooling gas inlet near the shaft end T003, which is suitable for receiving cooling gas and cooling the dry gas seal, and the main shaft T002 is provided with a cooling gas outlet near the impeller T001, which is suitable for drawing out cooling gas and merging with the first working fluid gas.

[0067] According to an embodiment of the present disclosure, the heat pump heating system further includes a second regenerator H006. The second regenerator H006 is connected to the evaporator H005 and the second compressor C002, as well as the heat output terminal H004 and the throttle valve YJ001, and is suitable for recovering waste heat of the heat pump heating system and performing heat exchange with the second working fluid gas.

[0068] In some specific embodiments, whether a second heat regenerator is needed in the heat pump heating system can be considered based on the actual operation and design status of the second working fluid. If the addition of the second heat regenerator does not significantly improve the performance of the heat pump heating system, there is no need to add a second heat regenerator.

[0069] According to the embodiment of the present disclosure, the circulation process of the heat pump heating system is as follows: part of the CO2 from the outlet of the cooler H003 in the Brayton cycle system enters the inlet part of the evaporator H005 in the heat pump heating system through the first branch X001, and then mixes with the CO2 in the heat pump heating system, and enters the second regenerator H006 to absorb heat after being heated by the evaporator H005. The CO2 after absorbing heat enters the second compressor C002 for pressurization, and then part of the CO2 enters the Brayton cycle system through the second branch X002 to cool the turbine component TU001, and the remaining CO2 enters the heat output end H004 to release heat, and after releasing heat, continues to enter the second regenerator H006 to dissipate heat, and then enters the throttle valve YJ001 for throttling and pressure reduction, completing the circulation of the heat pump heating system.

[0070] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present disclosure. It should be understood that the above description is only a specific embodiment of the present disclosure and is not intended to limit the present disclosure. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present disclosure should be included in the protection scope of the present disclosure.

Claims

1. A combined cycle system for turbine self-cooling of a supercritical carbon dioxide Brayton cycle, comprising: A Brayton cycle system, configured to perform a Brayton cycle using supercritical carbon dioxide as a first working gas, and output mechanical energy through a turbine component, and output electrical energy through an energy conversion component; The heat pump heating system is configured to output heat at a heat output end using carbon dioxide as a second working gas; as well as A turbine cooling branch is connected to the Brayton cycle system and the heat pump heating system, wherein the turbine cooling branch is configured to draw out at least a portion of the first working fluid gas as exchange gas and deliver it to the heat pump heating system, and to deliver at least a portion of the second working fluid gas as cooling gas to the turbine assembly, so as to achieve self-cooling of the turbine assembly and replenish the first working fluid gas to the Brayton cycle system.

2. The combined cycle system according to claim 1, wherein: The turbine cooling branch comprises: A first branch, wherein the inlet of the first branch is connected to the work-doing rear section of the Brayton cycle system, the outlet of the first branch is connected to the work-doing front section of the heat pump heating system, and the first branch is suitable for drawing out at least part of the first working fluid gas after work in the Brayton cycle system as exchange gas, and transporting it to the heat pump heating system to mix with the second working fluid gas; The second branch is adapted to lead out at least a portion of the second working fluid gas in the heat pump heating system as cooling gas, and transport it to the turbine assembly to cool the turbine assembly; The flow rates of the exchange air and the cooling air are the same.

3. The combined cycle system according to claim 2, wherein: The first branch comprises: a first pressure regulating component, adapted to adjust the pressure of the exchange gas so that the exchange gas enters the heat pump heating system through the first branch; A first flow regulating component, adapted to adjust the flow of the exchange gas; The second branch includes a second flow regulating component, and the second flow regulating component is suitable for adjusting the flow of the cooling air so that the flow of the cooling air is the same as the flow of the exchange air.

4. The combined cycle system according to claim 3, wherein the flow rates of the exchange gas and the cooling gas are 0.15-0.4 kg / s.

5. The combined cycle system according to claim 2, wherein: The pressure of the exchange gas is 7.5-8.5Mpa, and the temperature of the exchange gas is 33-35°C; The pressure of the cooling gas is 9-18 MPa, and the temperature of the cooling gas is 90-120°C.

6. The combined cycle system according to claim 1, wherein: The Brayton cycle system comprises: A first compressor, adapted to pressurize the first working fluid gas; a heater configured to receive heat from outside the combined cycle system and heat the pressurized first working fluid gas; A turbine assembly, adapted to receive the heated and pressurized first working fluid gas, and accommodate the heated and pressurized first working fluid gas to expand and output mechanical energy; an energy conversion component adapted to receive the mechanical energy, convert and output electrical energy, A cooler, wherein the inlet of the cooler is connected to the outlet of the turbine assembly, and is suitable for receiving and cooling the first working fluid gas after work. The outlet of the cooler is connected to the inlet of the first compressor so that the first working fluid gas after cooling can return to the first compressor for the next cycle.

7. The combined cycle system according to claim 6, wherein: The Brayton cycle system also includes a first regenerator, which is respectively connected to the first compressor and the heater, as well as the turbine assembly and the cooler, and is suitable for recovering waste heat of the Brayton cycle system and performing heat exchange with the first working fluid gas.

8. The combined cycle system according to claim 6, wherein: The turbine assembly comprises: an impeller, adapted to convert thermal energy into mechanical energy; A main shaft, adapted to support the impeller and transmit rotational torque; A shaft end, configured to prevent leakage of the first working fluid gas through a dry gas seal; Among them, a cooling gas inlet is opened near the shaft end of the main shaft, which is suitable for receiving the cooling gas and cooling the dry gas seal. A cooling gas outlet is opened near the impeller of the main shaft, which is suitable for leading out the cooling gas and merging it with the first working fluid gas.

9. The combined cycle system according to claim 1, wherein: The heat pump heating system comprises: an evaporator configured to receive heat from outside the combined system and heat the second working fluid gas; a second compressor, adapted to pressurize the heated second working fluid gas; A heat output end, adapted to receive the heated and pressurized second working fluid gas and output heat; A throttle valve, wherein the inlet of the throttle valve is connected to the outlet of the heat output end, and the outlet of the throttle valve is connected to the inlet of the evaporator, and is suitable for reducing the pressure of the second working fluid gas.

10. The combined cycle system according to claim 9, wherein: The heat pump heating system also includes: The second regenerator is connected to the evaporator and the second compressor, as well as the heat output end and the throttle valve, respectively, and is suitable for recovering waste heat of the heat pump heating system and performing heat exchange with the second working fluid gas.

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