Ejector enhanced liquid carbon dioxide compression energy storage system and method

Abstract

The invention relates to an ejector enhanced liquid carbon dioxide compression energy storage system and method. The system comprises a low-pressure liquid CO2 storage tank, a throttle valve A, a methanol heat exchanger A, a compressor A, a heat exchanger A, a compressor B, a heat exchanger B, a methanol heat exchanger C, an ejector A, a medium-low pressure liquid CO2 storage tank, a pump, a methanol heat exchanger D, a heat exchanger C, a steam turbine A, a heat exchanger D, a steam turbine B, an ejector B, a methanol heat exchanger B, a throttle valve B, a hot water storage tank, a cold water storage tank, a high-temperature methanol tank B and a low-temperature methanol tank B, and a high-temperature methanol tank A and a low-temperature methanol tank A. The energy comprehensive utilization efficiency of the system is improved, the problem of insufficient energy comprehensive utilization is effectively solved, and energy waste is reduced. The energy storage efficiency is effectively improved, and the energy loss of the system is reduced. And the utilization efficiency and the safety performance of the system are improved. And the consumption of the phase change material is reduced. And the stability and the reliability of the system are improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of electric energy storage, and in particular relates to an ejector-enhanced liquid carbon dioxide compression energy storage system and method. Background Art

[0002] In recent years, due to the increasingly severe situation of fossil fuel shortage and global warming, the use of renewable energy has gradually become dominant worldwide. However, the instability, intermittency and peak load of new renewable energy are also a key challenge. Therefore, power storage technology has become an important means to solve this problem. This technology is the process of converting non-peak electricity into other forms of energy and converting it back into electrical energy as needed. In order to improve the energy utilization rate of energy storage systems, the use of ejectors to enhance energy storage is considered to be a technical solution. Traditional compressed carbon dioxide energy storage systems have the following technical problems:

[0003] 1. Comprehensive utilization of energy:

[0004] Traditional liquid compressed carbon dioxide energy storage systems have the problem of insufficient comprehensive energy utilization and fail to effectively recover and utilize the heat energy and cold energy in the process of carbon dioxide liquefaction and vaporization.

[0005] 2. Energy storage efficiency issues:

[0006] Traditional liquid compressed carbon dioxide energy storage systems have energy losses during the energy conversion process, especially in the compression and expansion stages.

[0007] 3. Heat loss problem:

[0008] In traditional liquid compressed carbon dioxide energy storage systems, the heat generated during the compression and expansion of carbon dioxide cannot be effectively recovered and utilized, resulting in heat energy loss in the system.

[0009] 4. Circulatory system instability problem:

[0010] There are challenges in the stability of the circulation system in traditional liquid compressed carbon dioxide energy storage systems, especially in the process of releasing and storing liquid carbon dioxide, where problems such as carbon dioxide being difficult to condense occur.

[0011] 5. Overall system reliability issues:

[0012] There is a bottleneck in the reliability of traditional liquid compressed carbon dioxide energy storage systems, because their operation under complex working conditions often leads to system failures, and the storage of liquid carbon dioxide under high-pressure conditions poses a great safety hazard. Summary of the invention

[0013] The object of the present invention is to provide an ejector-enhanced liquid carbon dioxide compression energy storage system and method to solve the above-mentioned technical problems.

[0014] The present invention provides an ejector-enhanced liquid carbon dioxide compression energy storage system, comprising a low-pressure liquid CO2 storage tank, a throttle valve A, a methanol heat exchanger A, a compressor A, a heat exchanger A, a compressor B, a heat exchanger B, a methanol heat exchanger C, an ejector A, a medium- and low-pressure liquid CO2 storage tank, a pump, a methanol heat exchanger D, a heat exchanger C, a steam turbine A, a heat exchanger D, a steam turbine B, an ejector B, a methanol heat exchanger B, a throttle valve B, a hot water storage tank, a cold water storage tank, a high-temperature methanol tank B, a low-temperature methanol tank B, a high-temperature methanol tank A, and a low-temperature methanol tank A;

[0015] The first outlet of the low-pressure liquid CO2 storage tank is connected to the inlet of the throttle valve A. The outlet of the throttle valve A is divided into two paths, one of which is connected to the inlet of the injector A through the methanol heat exchanger A, the compressor A, the heat exchanger A, the compressor B, the heat exchanger B, the methanol heat exchanger C in sequence, and the other is directly connected to the inlet of the injector A;

[0016] The medium-low pressure liquid CO2 storage tank is connected to the inlet of the injector B through the pump, methanol heat exchanger D, heat exchanger C, turbine A, heat exchanger D, and turbine B in sequence, and the outlet of the injector B is connected to the inlet of the low pressure liquid CO2 storage tank through the methanol heat exchanger B;

[0017] The second outlet of the low-pressure liquid CO2 storage tank is connected to the inlet of the injector B;

[0018] The outlet of the methanol heat exchanger B is connected to the inlet of the methanol heat exchanger A through the high-temperature methanol tank A, and the outlet of the methanol heat exchanger A is connected to the inlet of the methanol heat exchanger B through the low-temperature methanol tank A;

[0019] The outlets of the heat exchanger A and the heat exchanger B are connected to the inlet of the hot water storage tank, and the outlet of the hot water storage tank is connected to the inlet of the heat exchanger D and the heat exchanger C; the outlets of the heat exchanger D and the heat exchanger C are connected to the inlet of the cold water storage tank, and the outlet of the cold water storage tank is connected to the inlet of the heat exchanger A and the heat exchanger B;

[0020] The outlet of the methanol heat exchanger C is connected to the inlet of the high-temperature methanol tank B, the outlet of the high-temperature methanol tank B is connected to the inlet of the methanol heat exchanger D, the outlet of the methanol heat exchanger D is connected to the inlet of the low-temperature methanol tank B, and the outlet of the low-temperature methanol tank B is connected to the inlet of the methanol heat exchanger C.

[0021] The present invention also provides a method for enhancing liquid carbon dioxide compression energy storage using an ejector of the system, comprising:

[0022] During the energy storage process, liquid carbon dioxide is released from the first outlet of the low-pressure liquid CO2 storage tank, is depressurized by the throttle valve A and is split into two streams. One part of the fluid passes through the methanol heat exchanger A to gasify the liquid carbon dioxide into a supercritical state and enters the compressor. Supercritical high-pressure carbon dioxide is obtained through the multi-stage compression and interstage cooling process of the multi-stage compression and interstage cooling device, and then it is liquefied into liquid carbon dioxide through the methanol heat exchanger C and enters the ejector A as the ejector main flow; the other part of the fluid is directly used as the secondary fluid of the ejector A, is mixed into medium- and low-pressure liquid carbon dioxide through the mixing chamber of the ejector A, and enters the medium- and low-pressure liquid CO2 storage tank.

[0023] Furthermore, the method further comprises:

[0024] During the energy release process, liquid carbon dioxide stored at medium and low pressures is released from the medium and low pressure liquid CO2 storage tanks, and the liquid carbon dioxide is pressurized by a booster pump to be elevated to high-pressure liquid carbon dioxide. The high-pressure liquid carbon dioxide is gasified to a supercritical state through the methanol heat exchanger D, and then undergoes a multi-stage expansion and inter-stage heating process of a multi-stage expansion and inter-stage heating device, and the carbon dioxide is used to drive the steam turbine to do work, thereby generating electrical energy; finally, the low-pressure carbon dioxide enters the ejector B as the active flow of the ejector; the low-pressure liquid carbon dioxide is depressurized from the second outlet of the low-pressure liquid CO2 storage tank through the throttle valve B, and is injected into the ejector B as a secondary fluid. In the ejector B, the two fluids are mixed into low-pressure carbon dioxide in the mixing chamber of the ejector B, and then the mixed low-pressure carbon dioxide is liquefied through the methanol heat exchanger B, and is stored again in the low-pressure liquid CO2 storage tank, waiting for the next cycle.

[0025] Furthermore, the method further comprises:

[0026] During the energy storage process, the compression heat generated during the compression of carbon dioxide is stored in the hot water storage tank; during the energy release process, the compression heat stored in the hot water storage tank is used to increase the temperature of the high-pressure carbon dioxide entering the turbine inlet.

[0027] Furthermore, the method further comprises:

[0028] During the energy storage process, the cold water in the cold water tank is used to reduce the temperature of the supercritical carbon dioxide at the outlet of each compressor; during the energy release process, the compression heat of the hot water tank is lowered after heat exchange and stored in the cold water tank until it reaches room temperature and waits for reuse in the next round of energy storage process.

[0029] Furthermore, the method further comprises:

[0030] During the energy release process, the cold energy generated during the gasification of carbon dioxide is stored in the cryogenic methanol tank B. During the energy storage process, the cold energy stored in the cryogenic methanol tank B is used to liquefy the supercritical carbon dioxide at the outlet of the compressor, so that it is converted into liquid carbon dioxide and then enters the ejector A to serve as the secondary flow of the ejector A main flow.

[0031] Furthermore, the ejector-enhanced liquid carbon dioxide compression energy storage method further comprises:

[0032] During the energy storage process, the heat generated during the liquefaction of carbon dioxide is stored in the high-temperature methanol tank B. During the energy release process, the heat stored in the high-temperature methanol tank B is used to vaporize the high-pressure liquid carbon dioxide pressurized by the pump, and finally sent to the turbine through the heat exchanger C to perform work.

[0033] Furthermore, the method further comprises:

[0034] During the energy storage process, the cold energy generated during the gasification of carbon dioxide is stored in the cryogenic methanol tank A; during the energy release process, the cold energy stored in the cryogenic methanol tank A is used to liquefy the two-phase mixture at the outlet of the ejector B, converting it into liquid carbon dioxide and then entering the low-pressure liquid CO2 storage tank.

[0035] Furthermore, the ejector-enhanced liquid carbon dioxide compression energy storage method further comprises:

[0036] In the energy release process, the heat generated by the liquefaction heat exchange of the two-phase mixture at the outlet of the ejector B is stored in the high-temperature methanol tank A, and finally sent to the low-pressure liquid CO2 storage tank for storage; in the energy storage process, the heat stored in the high-temperature methanol tank A is used to gasify the two-phase mixture after throttling and depressurization by the throttle valve A, so that it becomes supercritical carbon dioxide, and finally sent to the compressor for pressurization. Through the above scheme, the liquid carbon dioxide compression energy storage system and method enhanced by the ejector has the following technical effects:

[0037] 1) By introducing a methanol heat exchanger, the carbon dioxide at the outlet of the liquid CO2 storage tank can be gasified more conveniently and safely, and the problem that the carbon dioxide is not easily liquefied due to the limited low temperature of the condensed water during the energy release process is solved, thereby improving the comprehensive energy utilization efficiency of the system, effectively solving the problem of insufficient comprehensive energy utilization, and reducing energy waste.

[0038] 2) Through multi-stage compression, inter-stage cooling, multi-stage expansion and inter-stage heating, the energy storage efficiency is effectively improved and the energy loss of the system is reduced.

[0039] 3) By introducing an ejector during the energy storage process, the power consumption of the compressor for compressing a large amount of gas is reduced, and the low-pressure fluid is ejected by the high-pressure fluid to generate medium- and low-pressure fluids at the outlet of the mixing chamber, making it easier to store carbon dioxide at medium and low pressures, thereby improving the utilization efficiency and safety performance of the system.

[0040] 4) By adding an ejector during the energy release process, the pressure and temperature of the carbon dioxide at the turbine outlet are reduced, making the gas easier to condense before entering the liquid CO2 storage tank, thereby reducing the consumption of phase change materials.

[0041] 5) Through a reasonably designed circulation system, stable liquid carbon dioxide transmission between the low-pressure liquid CO2 storage tank and the medium- and low-pressure liquid CO2 storage tank is ensured, which effectively solves the problem of unstable circulation system in traditional systems and improves the stability and reliability of the system.

[0042] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention and implement it according to the contents of the specification, the following is a detailed description of the preferred embodiments of the present invention in conjunction with the accompanying drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0043] Figure 1 It is a structural schematic diagram of the ejector-enhanced liquid carbon dioxide compression energy storage system of the present invention. DETAILED DESCRIPTION

[0044] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0045] Ginseng Figure 1 As shown, this embodiment provides an ejector-enhanced liquid carbon dioxide compression energy storage system, including a low-pressure liquid CO2 storage tank, a throttle valve A, a methanol heat exchanger A, a compressor A, a heat exchanger A, a compressor B, a heat exchanger B, a methanol heat exchanger C, an ejector A, a medium- and low-pressure liquid CO2 storage tank, a pump, a methanol heat exchanger D, a heat exchanger C, a steam turbine A, a heat exchanger D, a steam turbine B, an ejector B, a methanol heat exchanger B, a throttle valve B, a hot water storage tank, a cold water storage tank, a high-temperature methanol tank B, a low-temperature methanol tank B, a high-temperature methanol tank A, and a low-temperature methanol tank A;

[0046] The first outlet of the low-pressure liquid CO2 storage tank is connected to the inlet of the throttle valve A. The outlet of the throttle valve A is divided into two paths, one of which is connected to the inlet of the injector A through the methanol heat exchanger A, the compressor A, the heat exchanger A, the compressor B, the heat exchanger B, the methanol heat exchanger C in sequence, and the other is directly connected to the inlet of the injector A;

[0047] The medium-low pressure liquid CO2 storage tank is connected to the inlet of the injector B through the pump, methanol heat exchanger D, heat exchanger C, turbine A, heat exchanger D, and turbine B in sequence, and the outlet of the injector B is connected to the inlet of the low pressure liquid CO2 storage tank through the methanol heat exchanger B;

[0048] The second outlet of the low-pressure liquid CO2 storage tank is connected to the inlet of the injector B;

[0049] The outlet of the methanol heat exchanger B is connected to the inlet of the methanol heat exchanger A through the high-temperature methanol tank A, and the outlet of the methanol heat exchanger A is connected to the inlet of the methanol heat exchanger B through the low-temperature methanol tank A;

[0050] The outlets of the heat exchanger A and the heat exchanger B are connected to the inlet of the hot water storage tank, and the outlet of the hot water storage tank is connected to the inlet of the heat exchanger D and the heat exchanger C; the outlets of the heat exchanger D and the heat exchanger C are connected to the inlet of the cold water storage tank, and the outlet of the cold water storage tank is connected to the inlet of the heat exchanger A and the heat exchanger B;

[0051] The outlet of the methanol heat exchanger C is connected to the inlet of the high-temperature methanol tank B, the outlet of the high-temperature methanol tank B is connected to the inlet of the methanol heat exchanger D, the outlet of the methanol heat exchanger D is connected to the inlet of the low-temperature methanol tank B, and the outlet of the low-temperature methanol tank B is connected to the inlet of the methanol heat exchanger C.

[0052] The ejector A is used to reduce the power consumption of the compressor in the process of compressing carbon dioxide during the energy storage process, and the ejector A outlet is medium-low pressure carbon dioxide, which improves the reliability of high-pressure storage of the carbon dioxide storage tank.

[0053] The ejector B is used to lower the condensation temperature of carbon dioxide during the energy release process, making it easier to condense and liquefy and send it to a low-pressure liquid CO2 storage tank for storage.

[0054] The system operates the ejector and compressed carbon dioxide energy storage in combination. In the energy storage stage, the high-pressure CO2 at the compressor outlet is used as the active flow of the ejector A to eject the low-pressure CO2 before compression, and the medium-low-pressure CO2 enters the storage tank; during the peak period of electricity consumption, the medium-low-pressure CO2 is pressurized to high-pressure CO2 by a pump and then generates electricity through an expander. Before the low-pressure CO2 enters the low-pressure CO2 storage tank, the CO2 condensation temperature is reduced by the ejector B, and finally condensed into liquid to enter and exit the low-pressure CO2 storage tank. The present invention reduces the power consumption of the compressor by adding an ejector in the energy storage stage, and liquefies and stores the condensed medium-low-pressure CO2, thereby improving the safety performance of the storage tank. In the energy release stage, the ejector is used to reduce the condensation temperature of the low-pressure CO2, making it easier to condense, reducing the temperature regulation cost, and extending the service life of the components.

[0055] The present invention also provides a method for enhancing liquid carbon dioxide compression energy storage using an ejector of the system, comprising:

[0056] During the energy storage process, liquid carbon dioxide is released from the first outlet of the low-pressure liquid CO2 storage tank, depressurized by throttle valve A and split into two streams. One part of the fluid passes through methanol heat exchanger A to gasify (convert to gaseous state) the liquid carbon dioxide into a supercritical state and enters the compressor. Supercritical high-pressure carbon dioxide is obtained through multi-stage compression and interstage cooling of multi-stage compression and interstage cooling devices (compressor A, heat exchanger A, compressor B, heat exchanger B), and then liquefied into liquid carbon dioxide through methanol heat exchanger C and enters ejector A as the main flow of the ejector; the other part of the fluid is directly used as the secondary fluid of ejector A, mixed into medium and low pressure liquid carbon dioxide through the mixing chamber of ejector A, and enters the medium and low pressure liquid CO2 storage tank. Among them, the temperature of carbon dioxide is increased when the liquid carbon dioxide is gasified by methanol heat exchanger A, and the cold generated during the heating process of carbon dioxide is stored in low-temperature methanol tank A for use in the energy release process.

[0057] In this embodiment, the method further includes:

[0058] In the energy release process, the liquid carbon dioxide stored in the medium and low pressure is released from the medium and low pressure liquid CO2 storage tank, and the liquid carbon dioxide is pressurized by the booster pump to be raised to high pressure liquid carbon dioxide, and the high pressure liquid carbon dioxide is gasified to a supercritical state through the methanol heat exchanger D, and then through the multi-stage expansion and inter-stage heating process of the multi-stage expansion and inter-stage heating device (heat exchanger A, turbine A, heat exchanger D, turbine B), the carbon dioxide is used to drive the turbine to expand and do work, thereby generating electrical energy, wherein the cold generated in the gasification process is used in the energy storage process; finally, the low pressure carbon dioxide enters the ejector B as the ejector main flow; the low pressure liquid carbon dioxide is depressurized from the second outlet of the low pressure liquid CO2 storage tank through the throttle valve B, and is injected into the ejector B as a secondary fluid. In the ejector B, the two fluids are mixed into low pressure carbon dioxide in the mixing chamber of the ejector B, and then the low pressure carbon dioxide obtained by the mixture is liquefied through the methanol heat exchanger B, and is stored again in the low pressure liquid CO2 storage tank, waiting for the next cycle.

[0059] In this embodiment, the method further includes:

[0060] In the energy storage process, the compression heat generated during the compression of carbon dioxide is stored in the hot water storage tank; in the energy release process, the compression heat stored in the hot water storage tank is used to increase the temperature of the high-pressure carbon dioxide entering the turbine inlet. The hot water storage tank can increase the turbine inlet temperature and increase the turbine's work capacity.

[0061] In this embodiment, the method further includes:

[0062] During the energy storage process, the cold water in the cold water tank is used to reduce the temperature of the supercritical carbon dioxide at the outlet of each compressor; during the energy release process, the compression heat of the hot water tank is lowered after heat exchange and stored in the cold water tank until it reaches room temperature and waits for reuse in the next round of energy storage process.

[0063] Using a cold water storage tank can lower the compressor inlet temperature and reduce the compressor power consumption.

[0064] In this embodiment, the method further includes:

[0065] During the energy release process, the cold energy generated during the gasification of carbon dioxide is stored in the cryogenic methanol tank B. During the energy storage process, the cold energy stored in the cryogenic methanol tank B is used to liquefy the supercritical carbon dioxide at the outlet of the compressor, so that it is converted into liquid carbon dioxide and then enters the ejector A to serve as the secondary flow of the ejector A main flow.

[0066] In this embodiment, the method further includes:

[0067] During the energy storage process, the heat generated during the liquefaction of carbon dioxide is stored in the high-temperature methanol tank B. During the energy release process, the heat stored in the high-temperature methanol tank B is used to vaporize the high-pressure liquid carbon dioxide pressurized by the pump, and finally sent to the turbine through the heat exchanger C to perform work.

[0068] In this embodiment, the method further includes:

[0069] During the energy storage process, the cold energy generated during the gasification of carbon dioxide is stored in the cryogenic methanol tank A; during the energy release process, the cold energy stored in the cryogenic methanol tank A is used to liquefy the two-phase mixture at the outlet of the ejector B, converting it into liquid carbon dioxide and then entering the low-pressure liquid CO2 storage tank.

[0070] In this embodiment, the method further includes:

[0071] During the energy release process, the heat generated by the liquefaction heat exchange of the two-phase mixture at the outlet of the ejector B is stored in the high-temperature methanol tank A, and finally sent to the low-pressure liquid CO2 storage tank for storage; during the energy storage process, the heat stored in the high-temperature methanol tank A is used to vaporize the two-phase mixture after throttling and reducing the pressure by the throttle valve A, so that it becomes supercritical carbon dioxide, and finally sent to the compressor for pressurization.

[0072] The method and system for injector-enhanced liquid carbon dioxide compression energy storage have the following technical effects:

[0073] 1) By introducing a methanol heat exchanger, the carbon dioxide at the outlet of the liquid CO2 storage tank can be gasified more conveniently and safely, and the problem that the carbon dioxide is not easily liquefied due to the limited low temperature of the condensed water during the energy release process is solved, thereby improving the comprehensive energy utilization efficiency of the system, effectively solving the problem of insufficient comprehensive energy utilization, and reducing energy waste.

[0074] 2) Through multi-stage compression, inter-stage cooling, multi-stage expansion and inter-stage heating, the energy storage efficiency is effectively improved and the energy loss of the system is reduced.

[0075] 3) By introducing an ejector during the energy storage process, the power consumption of the compressor for compressing a large amount of gas is reduced, and the low-pressure fluid is ejected by the high-pressure fluid to generate medium- and low-pressure fluids at the outlet of the mixing chamber, making it easier to store carbon dioxide at medium and low pressures, thereby improving the utilization efficiency and safety performance of the system.

[0076] 4) By adding an ejector during the energy release process, the pressure and temperature of the carbon dioxide at the turbine outlet are reduced, making the gas easier to condense before entering the liquid CO2 storage tank, thereby reducing the consumption of phase change materials.

[0077] 5) Through a reasonably designed circulation system, stable liquid carbon dioxide transmission between the low-pressure liquid CO2 storage tank and the medium- and low-pressure liquid CO2 storage tank is ensured, which effectively solves the problem of unstable circulation system in traditional systems and improves the stability and reliability of the system.

[0078] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. It should be pointed out that a person skilled in the art can make several improvements and modifications without departing from the technical principles of the present invention, and these improvements and modifications should also be regarded as within the scope of protection of the present invention.

Claims

1. An ejector-enhanced liquid carbon dioxide compression energy storage system, characterized in that: Including low-pressure liquid CO2 storage tank, throttle valve A, methanol heat exchanger A, compressor A, heat exchanger A, compressor B, heat exchanger B, methanol heat exchanger C, ejector A, medium and low pressure liquid CO2 storage tank, pump, methanol heat exchanger D, heat exchanger C, steam turbine A, heat exchanger D, steam turbine B, ejector B, methanol heat exchanger B, throttle valve B, hot water storage tank, cold water storage tank, high temperature methanol tank B, low temperature methanol tank B, high temperature methanol tank A, low temperature methanol tank A; The first outlet of the low-pressure liquid CO2 storage tank is connected to the inlet of the throttle valve A. The outlet of the throttle valve A is divided into two paths, one of which is connected to the inlet of the injector A through the methanol heat exchanger A, the compressor A, the heat exchanger A, the compressor B, the heat exchanger B, the methanol heat exchanger C in sequence, and the other is directly connected to the inlet of the injector A; The medium-low pressure liquid CO2 storage tank is connected to the inlet of the injector B through the pump, methanol heat exchanger D, heat exchanger C, turbine A, heat exchanger D, and turbine B in sequence, and the outlet of the injector B is connected to the inlet of the low pressure liquid CO2 storage tank through the methanol heat exchanger B; The second outlet of the low-pressure liquid CO2 storage tank is connected to the inlet of the injector B; The outlet of the methanol heat exchanger B is connected to the inlet of the methanol heat exchanger A through the high-temperature methanol tank A, and the outlet of the methanol heat exchanger A is connected to the inlet of the methanol heat exchanger B through the low-temperature methanol tank A; The outlets of the heat exchanger A and the heat exchanger B are connected to the inlet of the hot water storage tank, and the outlet of the hot water storage tank is connected to the inlet of the heat exchanger D and the heat exchanger C; the outlets of the heat exchanger D and the heat exchanger C are connected to the inlet of the cold water storage tank, and the outlet of the cold water storage tank is connected to the inlet of the heat exchanger A and the heat exchanger B; The outlet of the methanol heat exchanger C is connected to the inlet of the high-temperature methanol tank B, the outlet of the high-temperature methanol tank B is connected to the inlet of the methanol heat exchanger D, the outlet of the methanol heat exchanger D is connected to the inlet of the low-temperature methanol tank B, and the outlet of the low-temperature methanol tank B is connected to the inlet of the methanol heat exchanger C.

2. A method for enhancing liquid carbon dioxide compression energy storage using an ejector of the system according to claim 1, characterized in that: include: During the energy storage process, liquid carbon dioxide is released from the first outlet of the low-pressure liquid CO2 storage tank, is depressurized by the throttle valve A and is split into two streams. One part of the fluid passes through the methanol heat exchanger A to gasify the liquid carbon dioxide into a supercritical state and enters the compressor. Supercritical high-pressure carbon dioxide is obtained through the multi-stage compression and interstage cooling process of the multi-stage compression and interstage cooling device, and then it is liquefied into liquid carbon dioxide through the methanol heat exchanger C and enters the ejector A as the ejector main flow; the other part of the fluid is directly used as the secondary fluid of the ejector A, is mixed into medium- and low-pressure liquid carbon dioxide through the mixing chamber of the ejector A, and enters the medium- and low-pressure liquid CO2 storage tank.

3. The ejector-enhanced liquid carbon dioxide compression energy storage method according to claim 2, characterized in that: Also includes: During the energy release process, liquid carbon dioxide stored at medium and low pressures is released from the medium and low pressure liquid CO2 storage tanks, and the liquid carbon dioxide is pressurized by a booster pump to be elevated to high-pressure liquid carbon dioxide. The high-pressure liquid carbon dioxide is gasified to a supercritical state through the methanol heat exchanger D, and then undergoes a multi-stage expansion and inter-stage heating process of a multi-stage expansion and inter-stage heating device, and the carbon dioxide is used to drive the steam turbine to do work, thereby generating electrical energy; finally, the low-pressure carbon dioxide enters the ejector B as the active flow of the ejector; the low-pressure liquid carbon dioxide is depressurized from the second outlet of the low-pressure liquid CO2 storage tank through the throttle valve B, and is injected into the ejector B as a secondary fluid. In the ejector B, the two fluids are mixed into low-pressure carbon dioxide in the mixing chamber of the ejector B, and then the mixed low-pressure carbon dioxide is liquefied through the methanol heat exchanger B, and is stored again in the low-pressure liquid CO2 storage tank, waiting for the next cycle.

4. The ejector-enhanced liquid carbon dioxide compression energy storage method according to claim 3, characterized in that: Also includes: During the energy storage process, the compression heat generated during the compression of carbon dioxide is stored in a hot water storage tank; During the energy release process, the compression heat stored in the hot water storage tank is used to increase the temperature of the high-pressure carbon dioxide entering the turbine inlet.

5. The ejector-enhanced liquid carbon dioxide compression energy storage method according to claim 4, characterized in that: Also includes: During the energy storage process, the cold energy in the cold water storage tank is used to reduce the temperature of supercritical carbon dioxide at the outlet of each compressor; During the energy release process, the compression heat of the hot water storage tank becomes lower in temperature after heat exchange and is stored in the cold water storage tank until it reaches room temperature and waits for reuse in the next round of energy storage process.

6. The ejector-enhanced liquid carbon dioxide compression energy storage method according to claim 5, characterized in that: Also includes: During the energy release process, the cold energy generated during the gasification of carbon dioxide is stored in the low-temperature methanol tank B; In the energy storage process, the supercritical carbon dioxide at the outlet of the liquefied compressor is converted into liquid carbon dioxide by using the cold stored in the cryogenic methanol tank B. The carbon dioxide then enters the ejector A and serves as the ejector A main flow ejection secondary flow.

7. The ejector-enhanced liquid carbon dioxide compression energy storage method according to claim 6, characterized in that: Also includes: During the energy storage process, the heat generated during the liquefaction of carbon dioxide is stored in the high-temperature methanol tank B. During the energy release process, the heat stored in the high-temperature methanol tank B is used to vaporize the high-pressure liquid carbon dioxide pressurized by the pump, and finally sent to the turbine through the heat exchanger C to perform work.

8. The ejector-enhanced liquid carbon dioxide compression energy storage method according to claim 7, characterized in that: Also includes: During the energy storage process, the cold energy generated during the gasification of carbon dioxide is stored in the cryogenic methanol tank A; during the energy release process, the cold energy stored in the cryogenic methanol tank A is used to liquefy the two-phase mixture at the outlet of the ejector B, converting it into liquid carbon dioxide and then entering the low-pressure liquid CO2 storage tank.

9. The ejector-enhanced liquid carbon dioxide compression energy storage method according to claim 8, characterized in that: Also includes: During the energy release process, the heat generated by the liquefaction heat exchange of the two-phase mixture at the outlet of the ejector B is stored in the high-temperature methanol tank A, and finally sent to the low-pressure liquid CO2 storage tank for storage; during the energy storage process, the heat stored in the high-temperature methanol tank A is used to vaporize the two-phase mixture after throttling and reducing the pressure by the throttle valve A, so that it becomes supercritical carbon dioxide, and finally sent to the compressor for pressurization.

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