An ejector-enhanced liquid carbon dioxide compression energy storage system and method

Abstract

The present 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, medium- and low-pressure liquid CO2 storage tanks, 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. The present invention improves the system's comprehensive energy utilization efficiency, effectively solves the problem of insufficient comprehensive energy utilization, and reduces energy waste. It effectively improves energy storage efficiency and reduces system energy loss. It also enhances the system's utilization efficiency and safety performance, reduces the consumption of phase change materials, and improves the system's stability and reliability.

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 regulation of new renewable energy sources are also key challenges. Therefore, power storage technology has become an important means to solve this problem. This technology is the process of converting off-peak electricity into other forms of energy and converting it back into electricity as needed. In order to improve the energy utilization rate of energy storage systems, the use of ejectors to enhance energy storage is considered 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 and cold energy during the liquefaction and vaporization of carbon dioxide.

[0005] 2. Energy storage efficiency issues:

[0006] Traditional liquid compressed carbon dioxide energy storage systems suffer from energy loss during the energy conversion process, especially during 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 arise.

[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 purpose of the present invention is to provide an ejector-enhanced liquid carbon dioxide compression energy storage system and method to solve the above 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, compressor A, heat exchanger A, compressor B, heat exchanger B, and methanol heat exchanger C in sequence, and the other is directly connected to the inlet of the injector A.

[0016] The medium- and low-pressure liquid CO2 storage tanks are connected to the inlet of the ejector B through the pump, methanol heat exchanger D, heat exchanger C, steam turbine A, heat exchanger D, and steam turbine B in sequence, and the outlet of the ejector 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 ejector 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, reduced in pressure by the throttle valve A and 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 liquefied into liquid carbon dioxide through the methanol heat exchanger C and enters the ejector A as the active flow of the ejector; the other part of the fluid is directly used as the secondary fluid of the ejector A, and 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, the 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 interstage heating process of the multi-stage expansion and interstage heating device, and the carbon dioxide is used to drive the steam turbine to do work, thereby generating electricity; finally, the low-pressure carbon dioxide enters the ejector B and serves 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 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 capacity in the cold water tank is used to reduce the temperature of the supercritical carbon dioxide at the outlet of each stage of compressor; during the energy release process, the compression heat of the hot water tank is cooled down 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 carbon dioxide gasification process is stored in the low-temperature methanol tank B; during the energy storage process, the cold energy stored in the low-temperature methanol tank B is used to liquefy the supercritical carbon dioxide at the outlet of the compressor, converting it into liquid carbon dioxide and then entering the ejector A to serve as the secondary flow induced by the active flow of the ejector A.

[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 carbon dioxide gasification process 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] During the energy release process, the heat generated by the liquefaction heat exchange of the two-phase mixture at the outlet of 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 depressurization by throttle valve A, turning it into supercritical carbon dioxide, which is finally sent to the compressor for pressurization. Through the above scheme, the system and method for enhancing the compression energy storage of liquid carbon dioxide through the ejector have 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. This solves the problem of carbon dioxide being difficult to liquefy due to the limited low temperature of condensed water during the energy release process, 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 rationally 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, effectively solving the problem of unstable circulation system in traditional systems and improving 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 with reference to 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 following embodiments of the present invention are described in further detail with reference to 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, compressor A, heat exchanger A, compressor B, heat exchanger B, and methanol heat exchanger C in sequence, and the other is directly connected to the inlet of the injector A.

[0047] The medium- and low-pressure liquid CO2 storage tanks are connected to the inlet of the ejector B through the pump, methanol heat exchanger D, heat exchanger C, steam turbine A, heat exchanger D, and steam turbine B in sequence, and the outlet of the ejector 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 ejector 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 outlet of the ejector A is medium- and low-pressure carbon dioxide, which improves the reliability of the 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] This system combines the operation of an ejector with compressed carbon dioxide energy storage. During the energy storage phase, the high-pressure CO2 at the compressor outlet acts as the active flow of ejector A to eject the pre-compression low-pressure CO2, resulting in medium- and low-pressure CO2 entering the storage tank. During peak electricity consumption, a pump is used to pressurize the medium- and low-pressure CO2 to high-pressure CO2, which is then passed through an expander to generate electricity. Before the low-pressure CO2 enters the low-pressure CO2 storage tank, the CO2 condensation temperature is lowered by ejector B, and finally condensed into a liquid that enters and exits the low-pressure CO2 storage tank. By adding an ejector during the energy storage phase, the present invention reduces the power consumption of the compressor and liquefies and stores the condensed medium- and low-pressure CO2, improving the safety performance of the storage tank. During the energy release phase, the ejector is used to lower the condensation temperature of the low-pressure CO2, making it easier to condense, reducing temperature regulation costs, and extending the service life of 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 portion of the stream passes through methanol heat exchanger A, where it vaporizes (converts to gas) the liquid carbon dioxide to a supercritical state before entering the compressor. Supercritical high-pressure carbon dioxide is obtained through a multi-stage compression and interstage cooling process involving a multi-stage compression and interstage cooling device (compressor A, heat exchanger A, compressor B, heat exchanger B). This supercritical high-pressure carbon dioxide is then liquefied into liquid carbon dioxide by methanol heat exchanger C and enters ejector A, serving as the ejector's primary flow. The other portion of the stream directly serves as the secondary fluid of ejector A, passing through the mixing chamber of ejector A to be mixed into medium- and low-pressure liquid carbon dioxide, which then enters the medium- and low-pressure liquid CO2 storage tank. The vaporization of the liquid carbon dioxide by methanol heat exchanger A raises the temperature of the carbon dioxide. The cooling energy generated during the carbon dioxide temperature increase is stored in low-temperature methanol tank A and used in the energy release process.

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

[0058] During the energy release process, liquid CO2 stored at medium and low pressures is released from the medium and low pressure liquid CO2 storage tanks. A booster pump pressurizes the liquid CO2 to high pressure liquid CO2. Passing through methanol heat exchanger D, the high pressure liquid CO2 is vaporized to a supercritical state. Subsequently, the CO2 undergoes a multi-stage expansion and interstage heating process (heat exchanger A, steam turbine A, heat exchanger D, and steam turbine B). The CO2 drives the turbine to expand and produce work, thereby generating electricity. The cooling energy generated during the vaporization process is used for energy storage. Finally, the low pressure CO2 enters ejector B, serving as the ejector's main flow. From the second outlet of the low pressure liquid CO2 storage tank, the low pressure liquid CO2 is depressurized by throttle valve B and injected into ejector B as a secondary fluid. Within ejector B, the two fluids mix in the mixing chamber of ejector B to form low pressure CO2. The resulting low pressure CO2 is then liquefied by methanol heat exchanger B and stored back in the low pressure liquid CO2 storage tank, awaiting the next cycle.

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

[0060] During the energy storage process, the heat of compression generated during the CO2 compression process is stored in a heat storage tank. During the energy release process, the heat of compression stored in the heat storage tank is used to increase the temperature of the high-pressure CO2 entering the turbine inlet. Using the heat storage tank can increase the turbine inlet temperature and enhance the turbine's work capacity.

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

[0062] During the energy storage process, the cold capacity in the cold water tank is used to reduce the temperature of the supercritical carbon dioxide at the outlet of each stage of compressor; during the energy release process, the compression heat of the hot water tank is cooled down 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 carbon dioxide gasification process is stored in the low-temperature methanol tank B; during the energy storage process, the cold energy stored in the low-temperature methanol tank B is used to liquefy the supercritical carbon dioxide at the outlet of the compressor, converting it into liquid carbon dioxide and then entering the ejector A to serve as the secondary flow induced by the active flow of the ejector A.

[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 carbon dioxide gasification process 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 ejector-enhanced liquid carbon dioxide compression energy storage method and system has 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. This solves the problem of carbon dioxide being difficult to liquefy due to the limited low temperature of condensed water during the energy release process, 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 rationally 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, effectively solving the problem of unstable circulation system in traditional systems and improving 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 for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the technical principles of the present invention. These improvements and modifications should also be regarded as 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, compressor A, heat exchanger A, compressor B, heat exchanger B, and methanol heat exchanger C in sequence, and the other is directly connected to the inlet of the injector A. The medium- and low-pressure liquid CO2 storage tanks are connected to the inlet of the ejector B through the pump, methanol heat exchanger D, heat exchanger C, steam turbine A, heat exchanger D, and steam turbine B in sequence, and the outlet of the ejector 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 ejector 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, reduced in pressure by the throttle valve A and 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 liquefied into liquid carbon dioxide through the methanol heat exchanger C and enters the ejector A as the active flow of the ejector; the other part of the fluid is directly used as the secondary fluid of the ejector A, and 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, the 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 interstage heating process of the multi-stage expansion and interstage heating device, and the carbon dioxide is used to drive the steam turbine to do work, thereby generating electricity; finally, the low-pressure carbon dioxide enters the ejector B and serves 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 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 is cooled down after heat exchange and stored in the cold water storage tank until it returns to 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 carbon dioxide gasification process is stored in the low-temperature methanol tank B; During 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 low-temperature methanol tank B. The carbon dioxide then enters the ejector A and serves as the secondary flow of the ejector A's main 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 carbon dioxide gasification process 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.

Images