Supercritical co2 photo-thermal power generation and liquid compression energy storage system and operation method thereof

Abstract

The application discloses a supercritical CO2 photo-thermal power generation and liquid compression energy storage system and an operation method thereof. The system realizes comprehensive energy storage by combining liquid compression CO2 mixture energy storage and supercritical CO2 mixture photo-thermal power generation through a core low-temperature molten salt storage tank, a solar heat absorber, a high-temperature molten salt storage tank, a molten salt heat exchanger, a high-temperature mixture storage tank, a turbine, a regenerator, a condenser, a low-temperature liquid mixture storage tank, an evaporator and a compressor. The system not only solves the defect that a traditional compressed air energy storage system needs a large storage space, but also avoids the technical difficulty that a new generation of liquefied compressed air energy storage system needs low-temperature cooling.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of solar energy and energy storage system, and particularly relates to a supercritical CO2 photo-thermal power generation and liquid compression energy storage system and an operation method thereof. BACKGROUND

[0002] With the increase of new energy, especially wind power and solar photovoltaic power generation, the impact of new energy power generation on the power grid is becoming greater and greater. In order to solve this problem, more and more researches are carried out in the direction of photovoltaic supporting energy storage, wind power supporting energy storage, and energy storage peak shaving power station. Although there are many forms of energy storage, such as pumped storage, battery energy storage, compressed air energy storage, heat storage, and flywheel energy storage. However, at present, only compressed air energy storage, heat storage, and pumped storage are suitable for large-scale energy storage. Although battery energy storage has the highest efficiency, its cost is too high, and it is suitable for small and compact applications such as new energy vehicles, but it is not suitable for large-scale energy storage of power station level. Flywheel energy storage is suitable for frequency modulation which requires fast response, and is also not suitable for large-scale energy storage of power station level. Compared with compressed air energy storage, pumped storage, and heat storage, pumped storage has the lowest cost and relatively high efficiency, but the disadvantage is that it needs to build a reservoir, and is only suitable for construction in areas rich in water resources such as rivers and lakes. Heat storage is a rising energy storage method in recent years, and is widely used in the field of solar photo-thermal power generation. However, heat storage cannot be used alone, but is used as a supporting system for solar power generation system. If used as a separate energy storage power station, the cost is relatively high at present. Compressed air energy storage is another energy storage method comparable to pumped storage.

[0003] Compressed air energy storage has successively experienced the development process of supplemental combustion compressed air energy storage power station and heat storage compressed air energy storage power station, and is currently developing towards liquid compressed air energy storage power station and supercritical compressed air energy storage power station. Traditional supplemental combustion compressed air energy storage power station and heat storage compressed air energy storage power station need to store a large amount of compressed air, and generally choose special topography such as natural caves, abandoned mines, underground cavities, and aquifers to store compressed air. The newly built heat storage compressed air energy storage power station in China mainly uses ground storage tanks and pipeline gas storage. There are also designs of underwater air bag storage of compressed air abroad. However, these storage methods all have the problems of large occupation of land and high investment. The storage space of the most advanced liquid compressed air energy storage and supercritical compressed air energy storage can be theoretically reduced to one twentieth of the original, but these two technologies involve low-temperature cooling technology, which needs to cool the air to below -200℃ and -196℃. The difficulty of cryogenic technology is large, and the investment is large. That is, while solving the problem of compressed air storage space, these two new technologies introduce new technical difficulties.

[0004] Meanwhile, solar thermal power generation gradually rises, an important advantage of solar thermal power generation is that it can use cheap heat storage method for energy storage, so solar thermal power generation is gradually regarded as a supporting energy storage power station or regulating power station of photovoltaic power generation, and the solar thermal power station as an energy storage power station is also a large-scale energy storage method, but the development of the solar thermal power station is restricted by the defects of the solar thermal power generation itself, and the cost is too high. When it is used as a solar power generation device alone, it is difficult to compete with photovoltaic power generation, and only when it is combined with energy storage requirements can it be comparable to photovoltaic power generation, that is, when the cost of the photovoltaic power station equipped with the energy storage system is examined, the price can be compared with the solar thermal power generation. And the solar thermal power station as an energy storage power station can only store solar heat, and if the power grid needs to store more power, the solar thermal power station itself has no energy storage advantage. SUMMARY

[0005] The purpose of the present application is to overcome the above-mentioned defects of the prior art, and to provide a supercritical CO2 light and heat power generation and liquid compression energy storage system and its operation method, so as to solve the problems of large occupation area of compressed air energy storage and high cost of solar energy storage in the prior art.

[0006] In order to achieve the above-mentioned purpose, the following technical solutions are adopted in the present application:

[0007] A supercritical CO2 light and heat power generation and liquid compression energy storage system, comprising a low-temperature molten salt storage tank, a solar heat absorber, a high-temperature molten salt storage tank, a molten salt heat exchanger, a high-temperature mixture storage tank, a turbine, a regenerator, a condenser, a low-temperature liquid mixture storage tank, an evaporator and a compressor;

[0008] The outlet of the low-temperature molten salt storage tank is connected with the inlet of the solar heat absorber and the molten salt side inlet of the molten salt heat exchanger respectively; the outlet of the solar heat absorber is connected with the inlet of the high-temperature molten salt storage tank; the outlet of the low-temperature molten salt storage tank and the outlet of the high-temperature molten salt storage tank are both connected with the molten salt side inlet of the molten salt heat exchanger; the molten salt side outlet of the molten salt heat exchanger is connected with the inlet of the high-temperature molten salt storage tank and the inlet of the low-temperature molten salt storage tank respectively;

[0009] The working medium side outlet of the molten salt heat exchanger is connected with the turbine and the high-temperature mixture storage tank respectively; the outlet of the turbine is connected with the hot side inlet of the regenerator and the inlet of the condenser respectively; the hot side outlet of the regenerator is connected with the inlet of the condenser; the cold side outlet of the regenerator is connected with the working medium inlet of the molten salt heat exchanger; the outlet of the condenser is connected with the low-temperature liquid mixture storage tank and the compressor respectively; the outlet of the low-temperature liquid mixture storage tank is connected with the evaporator; the outlet of the evaporator is connected with the inlet of the compressor; the outlet of the compressor is connected with the working medium inlet of the molten salt heat exchanger.

[0010] Further improvement of the present application is as follows:

[0011] Preferably, the turbine comprises a high-pressure turbine and a low-pressure turbine connected in sequence, the inlet of the high-pressure turbine is connected with the outlet of the working medium side of the molten salt heat exchanger, and the outlet of the low-pressure turbine is connected with the inlet of the condenser.

[0012] Preferably, the outlet of the high-pressure turbine is connected with the hot side inlet of the regenerator and the inlet of the low-pressure turbine respectively.

[0013] Preferably, the outlet of the compressor is connected with the cold side inlet of the regenerator and the working medium side inlet of the molten salt heat exchanger respectively.

[0014] Preferably, the outlet of the high-temperature mixture tank is connected with the working medium side inlet of the molten salt heat exchanger.

[0015] Preferably, the compressor comprises a low-pressure compressor and a high-pressure compressor connected in sequence, the inlet of the low-pressure compressor is connected with the outlet of the evaporator, and the outlet of the high-pressure compressor is connected with the working medium inlet of the molten salt heat exchanger.

[0016] Preferably, the outlet of the condenser is connected with the inlet of the high-pressure compressor.

[0017] A method for operating the supercritical CO2 photo-thermal power generation and liquid compression energy storage system, when the power grid stores excess power, the CO2 mixture working medium in the low-temperature liquid mixture tank enters the evaporator and evaporates into a gaseous state, the gaseous CO2 mixture working medium is pressurized by the low-pressure compressor and the high-pressure compressor in sequence and then enters the working medium side of the molten salt heat exchanger; the low-temperature molten salt in the low-temperature molten salt tank flows into the molten salt side of the molten salt heat exchanger, the low-temperature molten salt and the working medium side of the molten salt heat exchanger are heat-exchanged, and the molten salt after absorbing heat in the molten salt heat exchanger is stored in the high-temperature molten salt tank.

[0018] When storing solar energy, the low-temperature molten salt flows from the low-temperature molten salt tank into the solar heat absorber, and after absorbing heat, the molten salt is stored in the high-temperature molten salt tank.

[0019] A method for operating the supercritical CO2 photo-thermal power generation and liquid compression energy storage system, when outputting power, the high-temperature molten salt in the high-temperature molten salt tank enters the molten salt heat exchanger to release heat and is stored in the low-temperature molten salt tank; the CO2 mixture working medium in the high-temperature mixture tank enters the molten salt heat exchanger to absorb heat and then enters the turbine to do work, the CO2 mixture working medium after doing work is cooled into a liquid state in the condenser, and the liquid CO2 mixture working medium is stored in the low-temperature liquid mixture tank.

[0020] Preferably, when the high-pressure working medium of the high-temperature mixture storage tank is consumed, the high-pressure CO2 mixture pressurized by the compressor is heated in the regenerator and then enters the working medium side of the molten salt heat exchanger to absorb heat, and then does work in the high-pressure turbine; the CO2 mixture after doing work has a pressure above the critical pressure, and after heat is released in the hot side of the regenerator, it is cooled in the condenser, and then enters the high-pressure compressor to do work.

[0021] Compared with the prior art, the present application has the following beneficial effects:

[0022] The application discloses a supercritical CO2 photo-thermal power generation and liquid compression energy storage system, which realizes comprehensive energy storage by combining liquid compression CO2 mixture energy storage and supercritical CO2 mixture photo-thermal power generation through a core low-temperature molten salt storage tank, a solar heat absorber, a high-temperature molten salt storage tank, a molten salt heat exchanger, a high-temperature mixture storage tank, a turbine, a regenerator, a condenser, a low-temperature liquid mixture storage tank, an evaporator and a compressor. The system not only solves the defect of a large amount of storage space required by a traditional compressed air energy storage system, but also avoids the technical difficulty of low-temperature cooling required by a new generation of liquefied compressed air energy storage system. Meanwhile, the working range of the original energy storage system is expanded, and not only the excess power of a power grid can be stored, but also solar energy can be stored, and solar energy can be directly used for power generation. In addition, since part of the equipment (the high-temperature molten salt storage tank, the low-temperature molten salt storage tank, the molten salt heat exchanger, the high-pressure turbine, the high-pressure compressor, the condenser and corresponding pipeline accessories) is shared by the two systems, the overall investment is much less than the sum of the investments of the two independent systems. The two systems share part of the equipment, and can realize the respective functions of the two systems, thereby reducing the overall cost and improving the overall functional range of the system.

[0023] The application further discloses a running method of the supercritical CO2 photo-thermal power generation and liquid compression energy storage system, which not only solves the defect of a large amount of storage space required by a traditional compressed air energy storage system, but also avoids the technical difficulty of low-temperature cooling required by a new generation of liquefied compressed air energy storage system. Meanwhile, the working range of the original energy storage system is expanded, and not only the excess power of a power grid can be stored, but also solar energy can be stored, and solar energy can be directly used for power generation. In addition, since part of the equipment (the high-temperature molten salt storage tank, the low-temperature molten salt storage tank, the molten salt heat exchanger, the high-pressure turbine, the high-pressure compressor, the condenser and corresponding pipeline accessories) is shared by the two systems, the overall investment is much less than the sum of the investments of the two independent systems. The method not only solves the problem of a large occupation space of compressed air energy storage, but also does not introduce the technical difficulty of low-temperature cooling, that is, greatly expands the application range of compressed air energy storage, and is helpful for the development and utilization of new energy and the impact of unstable power sources on the power grid. BRIEF DESCRIPTION OF DRAWINGS

[0024] Figure 1 Figure 1 is a schematic diagram of an example 1 of the system of the present application.

[0025] Wherein, 1 is a low-temperature molten salt storage tank, 2 is a solar heat absorber, 3 is a high-temperature molten salt storage tank, 4 is a molten salt heat exchanger, 5 is a high-temperature mixture storage tank, 6 is a high-pressure turbine, 7 is a low-pressure turbine, 8 is a regenerator, 9 is a condenser, 10 is a low-temperature liquid mixture storage tank, 11 is an evaporator, 12 is a low-pressure compressor, and 13 is a high-pressure compressor. DETAILED DESCRIPTION

[0026] The application will be further described below in conjunction with the drawings:

[0027] In the description of the present application, it should be noted that the terms "center", "upper", "lower", "left", "right", "vertical", "horizontal", "inner", "outer", and the like indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the present application; the terms "first", "second", "third" are only for the purpose of description, and cannot be understood as indicating or implying relative importance; in addition, unless otherwise explicitly specified and limited, the terms "mounting", "connection", "connection" should be understood broadly, for example, it can be fixed connection, or detachable connection; it can be directly connected, or indirectly connected through an intermediate medium; it can be the communication inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0028] One of the embodiments of the present application discloses a supercritical CO2 mixture photo-thermal power generation and liquid compression energy storage system, which comprises a low-temperature molten salt storage tank 1, a solar heat absorber 2, a high-temperature molten salt storage tank 3, a molten salt heat exchanger 4, a high-temperature mixture storage tank 5, a high-pressure turbine 6, a low-pressure turbine 7, a regenerator 8, a condenser 9, a low-temperature liquid mixture storage tank 10, an evaporator 11, a low-pressure compressor 12, and a high-pressure compressor 13.

[0029] The molten salt heat exchanger 4 is provided with two heat exchange pipelines, one pipeline is the molten salt side, and the other pipeline is the working medium side. The outlet of the high-pressure compressor 13, the cold side outlet of the regenerator 8, and the outlet of the high-temperature mixture storage tank 5 are merged and connected with the working medium side inlet of the molten salt heat exchanger 4; the working medium side outlet of the molten salt heat exchanger 4 is divided into two paths, one path is communicated with the inlet of the high-temperature mixture storage tank 5, and the other path is communicated with the inlet of the high-pressure turbine 6. The outlet of the molten salt side of the molten salt heat exchanger 4 is divided into two paths, one path is communicated with the inlet of the low-temperature molten salt storage tank 1, and the other path is communicated with the inlet of the high-temperature molten salt storage tank 3.

[0030] The outlet of the low-temperature molten salt storage tank 1 is divided into two paths, one of which is connected with the inlet of the solar heat absorber 2, and the other is connected with the molten salt side inlet of the molten salt heat exchanger 4. The outlet of the solar heat absorber 2 is connected with the inlet of the high-temperature molten salt storage tank 3, and the outlet of the high-temperature molten salt storage tank 3 is connected with the molten salt side inlet of the molten salt heat exchanger 4. The outlet of the high-pressure turbine 6 is divided into two paths, one of which is connected with the inlet of the low-pressure turbine 7, and the other is connected with the hot side inlet of the regenerator 8. The outlet of the low-pressure turbine 7 is connected with the inlet of the condenser 9.

[0031] The hot side inlet of the regenerator 8 is connected with the outlet of the high-pressure turbine 6, and the hot side outlet of the regenerator 8 and the outlet of the low-pressure turbine 7 are connected with the hot side inlet of the condenser 9. The cold side inlet of the regenerator 8 is connected with the outlet of the high-pressure compressor 13, and the cold side outlet of the regenerator 8 is connected with the working medium side inlet of the molten salt heat exchanger 4.

[0032] The hot side outlet of the condenser 9 is divided into two paths, one of which is connected with the inlet of the high-pressure compressor 13, and the other is connected with the inlet of the low-temperature liquid mixture storage tank 10. The outlet of the low-temperature liquid mixture storage tank 10 is connected with the cold side inlet of the evaporator 11, and the cold side outlet of the evaporator 11 is connected with the inlet of the low-pressure compressor 12. The outlet of the low-pressure compressor 12 is connected with the inlet of the high-pressure compressor 13, and the outlet of the high-pressure compressor 13 is divided into two paths, one of which is connected with the cold side inlet of the regenerator 8, and the other is directly connected with the working medium side inlet of the molten salt heat exchanger 4.

[0033] The operation method of the application is as follows:

[0034] When the grid has excess power to be stored, first start the low-pressure compressor 12, the liquid CO2 mixture working medium stored in the low-temperature liquid mixture storage tank 10 is sucked into the cold side of the evaporator 11 to absorb heat, the liquid CO2 mixture working medium evaporates into gas, the gaseous CO2 mixture working medium is pressurized in the low-pressure compressor 12, and then sent to the high-pressure compressor 13 for further pressurization. The high-pressure and high-temperature CO2 mixture working medium output from the high-pressure compressor 13 enters the working medium side of the molten salt heat exchanger 4, at this time the pipeline between the outlet of the high-pressure compressor 13 and the inlet of the cold side of the regenerator 8 is closed, the high-pressure and high-temperature CO2 mixture working medium releases heat in the molten salt heat exchanger 4 and then enters the high-temperature mixture storage tank 5 for storage. At the same time, the low-temperature molten salt flows from the outlet of the low-temperature molten salt storage tank 1 into the molten salt side of the molten salt heat exchanger 4, absorbs heat in the molten salt heat exchanger 4, and then enters the high-temperature molten salt storage tank 3 for storage. At this time, the molten salt side of the molten salt heat exchanger 4 enters the low-temperature molten salt storage tank 1, the molten salt side of the molten salt heat exchanger 4 enters the solar heat absorber 2, and the pipeline between the solar heat absorber 2 and the high-temperature molten salt storage tank 3 is closed. The pipeline between the outlet of the high-temperature molten salt storage tank 3 and the inlet of the molten salt side of the molten salt heat exchanger 4 is also closed. If the heat of solar thermal energy needs to be stored at the same time, a part of the low-temperature molten salt flows from the outlet of the low-temperature molten salt storage tank 1 into the solar heat absorber 2, absorbs the heat of solar energy, and then enters the high-temperature molten salt storage tank 3 for storage. The pipeline between the outlet of the high-temperature molten salt storage tank 3 and the inlet of the molten salt side of the molten salt heat exchanger 4 is still closed, and the pipeline between the outlet of the molten salt side of the molten salt heat exchanger 4 and the inlet of the low-temperature molten salt storage tank 1 is also closed.

[0035] When the grid has excess power to be stored, first start the low-pressure compressor 12, the liquid CO2 mixture working medium stored in the low-temperature liquid mixture storage tank 10 is sucked into the cold side of the evaporator 11 to absorb heat, the liquid CO2 mixture working medium evaporates into gas, the gaseous CO2 mixture working medium is pressurized in the low-pressure compressor 12, and then sent to the high-pressure compressor 13 for further pressurization. The high-pressure and high-temperature CO2 mixture working medium output from the high-pressure compressor 13 enters the working medium side of the molten salt heat exchanger 4, at this time the pipeline between the outlet of the high-pressure compressor 13 and the inlet of the cold side of the regenerator 8 is closed, the high-pressure and high-temperature CO2 mixture working medium releases heat in the molten salt heat exchanger 4 and then enters the high-temperature mixture storage tank 5 for storage. At the same time, the low-temperature molten salt flows from the outlet of the low-temperature molten salt storage tank 1 into the molten salt side of the molten salt heat exchanger 4, absorbs heat in the molten salt heat exchanger 4, and then enters the high-temperature molten salt storage tank 3 for storage. At this time, the molten salt side of the molten salt heat exchanger 4 enters the low-temperature molten salt storage tank 1, the molten salt side of the molten salt heat exchanger 4 enters the solar heat absorber 2, and the pipeline between the solar heat absorber 2 and the high-temperature molten salt storage tank 3 is closed. The pipeline between the outlet of the high-temperature molten salt storage tank 3 and the inlet of the molten salt side of the molten salt heat exchanger 4 is also closed. If the heat of solar thermal energy needs to be stored at the same time, a part of the low-temperature molten salt flows from the outlet of the low-temperature molten salt storage tank 1 into the solar heat absorber 2, absorbs the heat of solar energy, and then enters the high-temperature molten salt storage tank 3 for storage. The pipeline between the outlet of the high-temperature molten salt storage tank 3 and the inlet of the molten salt side of the molten salt heat exchanger 4 is still closed, and the pipeline between the outlet of the molten salt side of the molten salt heat exchanger 4 and the inlet of the low-temperature molten salt storage tank 1 is also closed.

[0036] When the high pressure working medium in the high temperature mixture storage tank 5 is consumed, if there is still high temperature molten salt in the high temperature molten salt storage tank 3, the supercritical CO2 cycle can be switched to supply power to the power grid at this time. At this time, the high pressure compressor 13 is started, the high pressure CO2 mixture after being pressurized enters the cold side of the regenerator 8 to absorb heat, and then enters the working medium side of the molten salt heat exchanger 4 to continue to absorb heat, and then enters the high pressure turbine 6 to do work. The working medium after doing work has a pressure above the critical pressure, directly enters the hot side of the regenerator 8 to release heat, and then enters the hot side of the condenser 9 to continue to release heat. At this time, the working medium at the outlet of the condenser 9 is in a supercritical state with a pressure above the critical pressure, and the cooled working medium returns to the inlet of the high pressure compressor 13 to complete the cycle. In this process, the low pressure turbine 7 and the low pressure compressor 12 do not work, the inlet and outlet pipelines of the low pressure turbine 7, the inlet pipeline of the low temperature liquid mixture storage tank 10, the outlet pipeline of the low pressure turbine 7, the pipeline between the high pressure compressor 13 and the inlet of the working medium side of the molten salt heat exchanger 4, and the inlet and outlet pipelines of the high temperature mixture storage tank 5 are all closed.

[0037] The above only describes the preferred embodiments of the present application and is not used to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A supercritical CO2 solar thermal power generation and liquid compression energy storage system, characterized in that, It includes a low-temperature molten salt storage tank (1), a solar absorber (2), a high-temperature molten salt storage tank (3), a molten salt heat exchanger (4), a high-temperature mixture storage tank (5), a turbine, a regenerator (8), a condenser (9), a low-temperature liquid mixture storage tank (10), an evaporator (11), and a compressor; The outlet of the low-temperature molten salt storage tank (1) is connected to the inlet of the solar absorber (2) and the molten salt side inlet of the molten salt heat exchanger (4), respectively; the outlet of the solar absorber (2) is connected to the inlet of the high-temperature molten salt storage tank (3); the outlet of the low-temperature molten salt storage tank (1) and the outlet of the high-temperature molten salt storage tank (3) are both connected to the molten salt side inlet of the molten salt heat exchanger (4); the molten salt side outlet of the molten salt heat exchanger (4) is connected to the inlet of the high-temperature molten salt storage tank (3) and the inlet of the low-temperature molten salt storage tank (1), respectively. The working fluid side outlet of the molten salt heat exchanger (4) is connected to a turbine and a high-temperature mixture storage tank (5), respectively. The outlet of the turbine is connected to the hot side inlet of the regenerator (8) and the inlet of the condenser (9), respectively. The hot side outlet of the regenerator (8) is connected to the inlet of the condenser (9), and the cold side outlet of the regenerator (8) is connected to the working fluid inlet of the molten salt heat exchanger (4). The outlet of the condenser (9) is connected to the cryogenic liquid mixture storage tank (10) and the compressor respectively. The outlet of the cryogenic liquid mixture storage tank (10) is connected to the evaporator (11). The outlet of the evaporator (11) is connected to the inlet of the compressor. The outlet of the compressor is connected to the working fluid inlet of the molten salt heat exchanger (4). The turbine includes a high-pressure turbine (6) and a low-pressure turbine (7) connected in sequence. The inlet of the high-pressure turbine (6) is connected to the working fluid side outlet of the molten salt heat exchanger (4), and the outlet of the low-pressure turbine (7) is connected to the inlet of the condenser (9). The compressor includes a low-pressure compressor (12) and a high-pressure compressor (13) connected in sequence. The inlet of the low-pressure compressor (12) is connected to the outlet of the evaporator (11), and the outlet of the high-pressure compressor (13) is connected to the working fluid inlet of the molten salt heat exchanger (4). The outlet of the high-pressure turbine (6) is connected to the hot side inlet of the regenerator (8) and the inlet of the low-pressure turbine (7), respectively. The outlet of the high-pressure compressor (13) is connected to the cold side inlet of the regenerator (8) and the working fluid side inlet of the molten salt heat exchanger (4), respectively. The outlet of the high-temperature mixture storage tank (5) is connected to the working fluid side inlet of the molten salt heat exchanger (4); The outlet of the condenser (9) is connected to the inlet of the high-pressure compressor (13).

2. A method for operating the supercritical CO2 solar thermal power generation and liquid compression energy storage system as described in claim 1, characterized in that, When the power grid stores surplus electrical energy, the CO2 mixture working medium in the low-temperature liquid mixture storage tank (10) enters the evaporator (11) and evaporates into a gaseous state. The gaseous CO2 mixture working medium is pressurized by the low-pressure compressor (12) and the high-pressure compressor (13) in sequence, and then enters the working medium side of the molten salt heat exchanger (4). The low-temperature molten salt in the low-temperature molten salt storage tank (1) flows into the molten salt side of the molten salt heat exchanger (4). The low-temperature molten salt and the working medium side exchange heat in the molten salt heat exchanger (4). The molten salt that absorbs heat in the molten salt heat exchanger (4) is stored in the high-temperature molten salt storage tank (3). When storing solar energy, low-temperature molten salt flows from the low-temperature molten salt storage tank (1) into the solar heat absorber (2), absorbs heat, and then enters the high-temperature molten salt storage tank (3) for storage.

3. A method for operating the supercritical CO2 solar thermal power generation and liquid compression energy storage system as described in claim 1, characterized in that, When outputting electrical energy, the high-temperature molten salt in the high-temperature molten salt storage tank (3) enters the molten salt heat exchanger (4) to release heat and enters the low-temperature molten salt storage tank (1) for storage; the CO2 mixed working medium in the high-temperature mixture storage tank (5) enters the molten salt heat exchanger (4) to absorb heat and then enters the turbine to do work. After doing work, the CO2 mixed working medium is cooled into a liquid state in the condenser (9), and the liquid CO2 mixed working medium is stored in the low-temperature liquid mixture storage tank (10).

4. The operation method of the supercritical CO2 solar thermal power generation and liquid compression energy storage system according to claim 3, characterized in that, When the high-pressure working fluid in the high-temperature mixture storage tank (5) is consumed, the high-pressure CO2 mixture after being pressurized by the compressor absorbs heat in the regenerator (8) and then enters the working fluid side of the molten salt heat exchanger (4) to absorb heat and do work in the high-pressure turbine (6). After doing work, the pressure of the CO2 mixture is above the critical pressure. After releasing heat on the hot side of the regenerator (8), it is cooled in the condenser (9) and then enters the high-pressure compressor (13) to do work.

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