An artificial chamber compressed air energy storage system and method based on molten salt and water

Abstract

The present invention relates to a molten salt and water-based artificial cavern compressed air energy storage system and method, comprising an air compression system, an artificial cavern storage system, and an expansion system, all connected in series, as well as a molten salt heat storage and exchange system and a water heat storage and exchange system. The air compression system comprises one or more series-connected air compressors. The output pipeline of at least one air compressor passes through the heat exchangers and water coolers of the molten salt heat storage and exchange system and the water heat storage and exchange system, and is then connected to the input of a downstream air compressor or artificial cavern storage system. The expansion system comprises one or more series-connected turbine expanders. The output pipeline of the artificial cavern storage system passes through the heat exchangers of the water heat storage and exchange system and the molten salt heat storage and exchange system, and is then connected to the input of a downstream turbine expander. This solution can improve the system's power generation efficiency, reduce the capacity of the system's gas storage reservoir, lower the system's application cost, and expand the system's scope of use.

Description

Technical Field

[0001] The present invention belongs to the field of energy storage technology, and in particular relates to an artificial chamber compressed air energy storage system and method based on molten salt and water. Background Art

[0002] In the future, energy consumption will gradually shift from a fossil fuel-dominated structure to one dominated by renewable energy. For the power system, building a new power system dominated by renewable energy will be key to achieving the dual carbon goals. However, renewable energy generation such as wind and solar power differs from traditional coal-fired power generation. While traditional coal-fired power generation is readily available, wind and solar power generation is subject to intermittent and unstable power generation, influenced by weather factors and the diurnal cycle. This can disrupt the balance of the power grid. As the capacity of renewable energy generation such as wind and solar power continues to increase, it will impact the safe and stable operation of the power grid. To improve the safety and reliability of future power systems and further increase the proportion of renewable energy generation such as wind and solar power, the development of energy storage systems is crucial. Energy storage includes various technologies, including physical, chemical, electromagnetic, and pumped hydro. Each technology has distinct characteristics and application scenarios.

[0003] Compressed air energy storage is a type of physical energy storage technology with advantages such as long energy storage time, large energy storage capacity, and high energy storage efficiency. However, the structure of existing energy storage systems of this type is relatively simple, and there is still room for improvement in energy storage and power generation efficiency. In addition, compressed air energy storage requires specific geographical conditions to build a large gas storage reservoir to store compressed air. If above-ground gas tanks or underground artificial chambers are used, the construction cost will be high. Therefore, currently, it is generally only based on existing rock caves, salt caves, abandoned mines, etc. for construction, which greatly limits the promotion and application of this technology. Therefore, there is a need for a compressed air energy storage solution with a wider site selection range, more efficient energy storage, and lower application cost. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to provide an artificial cavern compressed air energy storage system and method based on molten salt and water, so as to achieve more efficient energy storage and power generation, and can be constructed in an artificial cavern at a lower cost, thereby broadening the application scope of the compressed air energy storage system.

[0005] According to the technical solution of the present invention, the present invention provides an artificial cavern compressed air energy storage system based on molten salt and water, comprising an air compression system, an artificial cavern storage system and an expansion system connected in series in sequence, and also comprising a molten salt storage and heat exchange system and a water storage and heat exchange system; the air compression system comprises one or more air compressors connected in series; the output end pipeline of at least one air compressor passes through the heat exchanger and water cooler of the molten salt storage and heat exchange system in sequence and is connected to the input end of the downstream air compressor or the artificial cavern storage system; the expansion system comprises one or more turbine expanders connected in series; the output end pipeline of the artificial cavern storage system passes through the heat exchanger of the water storage and heat exchange system and the molten salt storage and heat exchange system in sequence and is connected to the input end of the downstream turbine expander.

[0006] Furthermore, the molten salt heat storage and exchange system includes a salt cold storage tank and a salt hot storage tank, and the output end of the salt cold storage tank is connected to the input end of the salt hot storage tank after passing through the first molten salt heat exchanger and the second molten salt heat exchanger respectively through two pipelines; the output end of the salt hot storage tank is connected to the input end of the salt cold storage tank after passing through the third molten salt heat exchanger and the fourth molten salt heat exchanger respectively; the water heat storage and exchange system includes a water cold storage tank and a water hot storage tank, and the output end of the water cold storage tank is connected to the input end of the water hot storage tank after passing through the first water heat exchanger and the second water heat exchanger respectively; the output end of the water hot storage tank is connected to the input end of the water cold storage tank after passing through the third water heat exchanger and the fourth water heat exchanger respectively through two pipelines.

[0007] Furthermore, the air compression system includes a first-stage air compressor, a second-stage air compressor and a third-stage air compressor; the output end pipeline of the first-stage air compressor passes through the first molten salt heat exchanger, the first water heat exchanger and the first water cooler in sequence and is connected to the input end of the second-stage air compressor; the output end pipeline of the second-stage air compressor passes through the second molten salt heat exchanger, the second water heat exchanger and the second water cooler in sequence and is connected to the input end of the third-stage air compressor; the output end pipeline of the third-stage air compressor passes through the third water cooler and is connected to the input end of the artificial chamber storage system.

[0008] Furthermore, the expansion system includes a first-stage turbine expander and a second-stage turbine expander; the output end pipeline of the artificial chamber storage system passes through the third water heat exchanger and the third molten salt heat exchanger in sequence and is connected to the input end of the first-stage turbine expander; the output end pipeline of the first-stage turbine expander passes through the fourth water heat exchanger and the fourth molten salt heat exchanger in sequence and is connected to the input end of the second-stage turbine expander.

[0009] Furthermore, the air compressors in the air compression system are all connected to electric motors; and the turbine expander at the end of the expansion system is connected to a generator.

[0010] Furthermore, the air compression system is one set or multiple sets arranged in parallel.

[0011] The present invention also provides a method for storing compressed air energy in an artificial chamber based on molten salt and water, which is implemented based on the artificial chamber compressed air energy storage system based on molten salt and water of the present invention, and includes the following steps:

[0012] During periods of low electricity consumption, redundant electricity is input into the air compression system. The air compressor in the air compression system draws in air for compression, increasing the temperature and pressure of the air.

[0013] The compressed air output by the air compressor passes through the heat exchangers and water coolers of the molten salt heat storage and exchange system and the water storage and exchange system in sequence, reducing the temperature of the compressed air. At the same time, the temperature of the heat storage medium in the heat exchangers of the molten salt heat storage and exchange system and the water storage and exchange system increases. The heat storage medium in the two heat storage and exchange systems flows from their respective cold tanks through the heat exchangers into their respective hot tanks.

[0014] The air compression system outputs compressed air to the artificial chamber storage system for storage;

[0015] During peak electricity consumption, the artificial chamber storage system outputs compressed air to the expansion system. During the transportation process, the compressed air passes through the heat exchangers of the water storage heat exchange system and the molten salt storage heat exchange system in turn, causing the temperature of the compressed air to rise; at the same time, the temperature of the heat storage medium in the heat exchangers of the water storage heat exchange system and the molten salt storage heat exchange system decreases, and the heat storage medium in the two heat storage systems flows from their respective hot tanks through the heat exchangers into their respective cold tanks;

[0016] The turbine expander at the end of the expansion system outputs air to drive a generator to generate electricity.

[0017] Furthermore, the operating temperature range of the heat storage medium molten salt in the molten salt heat storage and exchange system is 150°C to 600°C, and the operating temperature range of the heat storage medium water in the water heat storage and exchange system is 40°C to 185°C.

[0018] Furthermore, the air is compressed in three stages by three air compressors connected in series, and the air temperature at the output ends of at least two air compressors is not lower than 340°C.

[0019] Furthermore, the pressure in the turbine expansion system shall not be lower than 10MPa7MPa, the temperature shall not be lower than 300°C, and the pressure fluctuation range shall not be lower than 1MPa; the pressure in the artificial chamber storage system shall not be lower than 4MPa, and the pressure fluctuation range shall not be lower than 1MPa.

[0020] Compared with the prior art, the beneficial technical effects of the present invention are as follows:

[0021] 1. The solution of the present invention adopts wide-temperature molten salt + pressurized water as the storage and heat exchange medium, which can improve the energy storage and power generation efficiency of the system and reduce the system cost. It is calculated that the net power-to-electricity conversion efficiency can be no less than 70%, and the investment is no more than 7,000 yuan / kw.

[0022] 2. The solution of the present invention adopts artificial chambers, which can expand the flexibility of the site selection of the compressed air energy storage system, avoid its site selection being restricted to specific geographical locations such as existing molten salt chambers and abandoned chambers, and by adopting different chamber types, the investment in the system can be effectively reduced.

[0023] 3. The solution of the present invention adopts an artificial chamber with high pressure and large pressure fluctuation range, an artificial chamber storage system with high pressure and large pressure fluctuation range, and a turbine expansion system with high pressure, high temperature and large pressure fluctuation range, which can effectively reduce the volume of the required chamber, reduce the investment in the system and expand the scope of use of the system, and can realize a compressed air energy storage system using an artificial chamber at a relatively low application cost.

[0024] 4. The solution of the present invention compresses compressed air in three stages, which has higher energy storage efficiency. At the same time, the waste heat of the third-stage compressed air can be used to provide heating for surrounding enterprises or residents, thereby helping the power industry achieve its dual carbon goals. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 It is a block diagram of the overall structure and working principle of the present invention.

[0026] Figure 2 It is a structural diagram of an embodiment of the present invention.

[0027] Figure 3 is a flow chart of a method according to an embodiment of the present invention.

[0028] Description of reference numerals in the accompanying drawings:

[0029] A. Air compression system; A1. First-stage air compressor; A2. Second-stage air compressor; A3. Third-stage air compressor; A4. First water cooler; A5. Second water cooler; A6. Third water cooler;

[0030] B. Artificial chamber storage system;

[0031] C. Expansion system; C1. One-stage turbine expander; C2. Two-stage turbine expander;

[0032] D, molten salt heat storage and exchange system; D1, first molten salt heat exchanger; D2, second molten salt heat exchanger; D3, third molten salt heat exchanger; D4, fourth molten salt heat exchanger; D5, salt storage cold tank; D6, salt storage hot tank;

[0033] E, water storage and heat exchange system; E1, first water heat exchanger; E2, second water heat exchanger; E3, third water heat exchanger; E4, fourth water heat exchanger; E5, cold water storage tank; E6, hot water storage tank;

[0034] M, electric motor; G, generator. DETAILED DESCRIPTION

[0035] The compressed air energy storage system of the present invention is an artificial cavern compressed air energy storage system with high efficiency, high pressure and large pressure fluctuation range based on wide-temperature molten salt and water as heat storage and exchange media. By adopting wide-temperature molten salt + water as heat storage and exchange media, the system can improve the system's power generation efficiency, reduce the capacity of the system's gas storage reservoir, reduce the system's application cost and expand the system's scope of use, so that the site selection of the compressed air energy storage system is no longer limited to existing caves or abandoned caves; at the same time, the waste heat of compressed air can also be used to provide heating for surrounding enterprises or residents, helping the power industry to achieve its dual carbon goals.

[0036] See also Figure 1 、 Figure 2 The present invention provides an artificial cavern compressed air energy storage system based on molten salt and water. Generally speaking, it includes an air compression system A, an artificial cavern storage system B and an expansion system C which are connected in series through a pipeline system, and also includes a molten salt storage and heat exchange system D and a water storage and heat exchange system E.

[0037] Air compression system A utilizes valley electricity to compress air, converting electrical energy into the internal energy of the air and the thermal energy of the heat storage medium in the heat storage and exchange system. Air compression system A comprises one or more air compressors connected in series, each of which is connected to a motor M for driving. The output pipeline of at least one air compressor passes through the heat exchanger and water cooler of the molten salt heat storage and exchange system D and the water storage and exchange system E, and then connects to the input of the downstream air compressor or the artificial chamber storage system B.

[0038] Artificial chamber storage system B is located underground and is used to store compressed air. Depending on the situation, it can adopt two types of gas storage, such as tunnel-type gas storage or large tank-type gas storage. By adopting different chamber types, the system investment can be effectively reduced.

[0039] The expansion system C releases the energy stored during the compression process during peak electricity demand, converting the internal energy of the air and the thermal energy of the heat storage medium in the heat storage and exchange system into electrical energy. Expansion system C comprises one or more turbine expanders connected in series, with the final turbine expander in expansion system C connected to a generator G (e.g., a steam turbine). The output pipeline of the artificial chamber storage system B passes through the heat exchangers of the water storage and exchange system E and the molten salt storage and exchange system D, then connects to the input of the downstream turbine expander.

[0040] The molten salt heat storage and exchange system D and the water heat storage and exchange system E are used to store the heat generated during the compression process and release the corresponding energy during the expansion process. The solution of the present invention combines the molten salt heat storage and exchange system D and the water heat storage and exchange system E. For example, the operating temperature range of the heat storage medium molten salt (wide temperature lava) in the molten salt heat storage and exchange system D is 180℃~550℃ (more preferably 150℃~600℃), and the operating temperature range of the heat storage medium water (pressurized water) in the water heat storage and exchange system E is 40℃~185℃. Combining the two can achieve cascade heat storage and exchange, reducing the compressed air from, for example, 400℃ to, for example, 60℃ and collecting and storing (basically) all the released heat energy, making full use of the respective characteristics of molten salt and water, maximizing the maximum storage capacity of the heat storage and exchange system, improving the energy storage and power generation efficiency of the system, and reducing system costs. Molten salt heat storage and exchange system D is difficult to achieve at low temperatures. Current products on the market can only operate up to 180°C. The low-temperature portion can only be recovered through water. If only molten salt heat storage and exchange system D is used, a significant amount of heat energy remains uncollected after the compressed air passes through the heat exchanger, resulting in energy waste. For water, operating at too high a temperature increases the cost of the storage system and makes it difficult to manufacture the water storage tank. Combining the two enables both high-temperature power generation and cascaded energy utilization, while also reducing costs. The expansion process mirrors this, with the heat storage mediums water and molten salt heating sequentially from low to high temperatures, releasing (substantially) all the stored heat energy. In addition to the organic combination of molten salt and water heat exchange methods, this solution also features high temperatures, high pressures, and a wide pressure fluctuation range, achieving high efficiency and low cost. For example, the molten salt temperature range allows for low temperatures down to 180°C, even 150°C, and compressor outlet temperatures can reach 340°C. According to calculations, a specific embodiment of this solution can achieve a net power-to-electricity conversion efficiency of no less than 70%, with an investment of no more than RMB 7,000 / kw.

[0041] The piping system includes various pipes for transporting gas or liquid and the necessary pumps ( Figure 2 As shown by the circle symbol with an arrow in the figure), valves and corresponding control systems, etc. These parts are components that are common to pipeline systems in various fields. The relevant existing technologies are very mature and are not the improvement points of the present invention, so they will not be described in detail.

[0042] The following Figure 2 The structure shown is taken as an example for detailed description, wherein, in order to clearly show the working process, each section of the pipeline is marked with a number and the flow direction of the fluid therein.

[0043] The molten salt heat storage and exchange system D includes a cold salt storage tank D5 and a hot salt storage tank D6. The output of cold salt storage tank D5 is connected to the input of hot salt storage tank D6 via two pipelines (pipelines 10, 11, and 12, and pipelines 10, 13, and 14), respectively, passing through a first molten salt heat exchanger D1 and a second molten salt heat exchanger D2. The output of hot salt storage tank D6 is connected to the input of cold salt storage tank D5 via two pipelines (pipelines 15, 18, 19, and 20, and pipelines 15, 16, 17, and 20), respectively, passing through a third molten salt heat exchanger D3 and a fourth molten salt heat exchanger D4. Thus, the molten salt heat storage and exchange system D forms a closed ring loop. During the compression process, the heat storage medium is pumped from the salt storage cold tank D5 to the salt storage hot tank D6, and the temperature increases during the transportation process; during the expansion process, the heat storage medium is pumped from the salt storage hot tank D6 to the salt storage cold tank D5, and the temperature decreases during the transportation process; at any time, the temperature of the heat storage medium in the salt storage cold tank D5 or the salt storage hot tank D6 remains basically consistent.

[0044] Similarly, the water storage and heat exchange system E includes a cold water storage tank E5 and a hot water storage tank E6. The output of cold water storage tank E5 is connected to the input of hot water storage tank E6 via two pipelines (pipelines 21, 22, and 23, and pipelines 21, 24, and 25), respectively, through a first water heat exchanger E1 and a second water heat exchanger E2. The output of hot water storage tank E6 is connected to the input of cold water storage tank E5 via two pipelines (pipelines 26, 29, and 30, and pipelines 26, 27, 28, and 30), respectively, through a third water heat exchanger E3 and a fourth water heat exchanger E4. Thus, the water storage heat exchange system E forms a closed loop. During the compression process, the heat storage medium is pumped from the cold water storage tank E5 to the hot water storage tank E6, and the temperature increases during the transportation process; during the expansion process, the heat storage medium is pumped from the hot water storage tank E6 to the cold water storage tank E5, and the temperature decreases during the transportation process; at any time, the temperature of the heat storage medium in the cold water storage tank E5 or the hot water storage tank E6 remains basically consistent.

[0045] It should be noted that the actual number of independent pipelines leading to the corresponding heat exchangers in the molten salt heat storage and exchange system D and the water heat storage and exchange system E is related to the number of air compressors in the air compression system A, specifically the number of air compressors minus 1, and is at least one pipeline (one set). For example, if three air compressors are connected in series, there are two pipelines (two sets); if two air compressors are connected in series, there is one pipeline (one set); if there is only one air compressor, the number of pipelines is also one (one set).

[0046] Figure 2In the preferred embodiment shown, air compression system A includes a primary air compressor A1, a secondary air compressor A2, and a tertiary air compressor A3. Primary air compressor A1 draws air through pipeline 1, and its output passes sequentially through pipeline 2, the first molten salt heat exchanger D1, pipeline 3, the first water heat exchanger E1, and the first water cooler A4, before being connected to the input of secondary air compressor A2 via pipeline 4. The output of secondary air compressor A2 passes sequentially through pipeline 5, the second molten salt heat exchanger D2, pipeline 6, the second water heat exchanger E2, and the second water cooler A5, before being connected to the input of tertiary air compressor A3 via pipeline 7. The output of tertiary air compressor A3 passes through pipeline 8 and the third water cooler A6, before being connected to the input of artificial chamber storage system B via pipeline 9.

[0047] In another embodiment, a heat exchanger is provided between the output end of the three-stage air compressor A3 and the third water cooler A6 to provide heat to the surrounding buildings. In addition, as needed, only one air compression system A may be provided, or another air compression system A' may be provided in parallel, or more sets may be provided in parallel. The structure of each air compression system is basically the same, and the output end is connected to the input end of the artificial chamber storage system B, wherein the heat storage and exchange parts are all interconnected with the same molten salt heat storage and exchange system D and water heat storage and exchange system E (that is, the water storage cold tank E5 and the water storage hot tank E6 can be considered to be shared, and the four molten salt heat exchangers can also be considered to be shared, etc.), or the molten salt heat storage and exchange system D and the water storage and heat exchange system E also have multiple sets respectively.

[0048] Expansion system C includes a first-stage turbine expander C1 and a second-stage turbine expander C2. The output of the artificial chamber storage system B passes through pipeline 31, the third water heat exchanger E3, and the third molten salt heat exchanger D3, before being connected to the input of the first-stage turbine expander C1 via pipeline 32. The output of the first-stage turbine expander C1 passes through the fourth water heat exchanger E4 and the fourth molten salt heat exchanger D4, before being connected to the input of the second-stage turbine expander C2 via pipeline 33. The output of the second-stage turbine expander C2 is connected to pipeline 34 to exhaust air. The first-stage turbine expander C1, the second-stage turbine expander C2, and the generator G are coaxially arranged.

[0049] See also Figure 3 Based on the above-mentioned compressed air energy storage system, the present invention also provides an artificial cavern compressed air energy storage method based on molten salt and water, which comprises the following steps:

[0050] Step S1: During a low electricity consumption period, redundant electric energy is input into an air compression system. An air compressor in the air compression system sucks in air for compression, thereby increasing the temperature and pressure of the air.

[0051] In step S2, the compressed air output by the air compressor passes through the heat exchangers of the molten salt heat storage and exchange system and the water storage and exchange system and the water cooler in sequence, thereby reducing the temperature of the compressed air; at the same time, the temperature of the heat storage medium in the heat exchangers of the molten salt heat storage and exchange system and the water storage and exchange system increases, and the heat storage medium in the two heat storage and exchange systems flows from their respective cold tanks through the heat exchangers into their respective hot tanks;

[0052] Step S3: the air compression system outputs compressed air to the artificial chamber storage system for storage;

[0053] For the above steps, preferably, the air is compressed in three sections through three air compressors connected in series, and the air temperature at the output ends of the first two air compressors is not lower than 340°C (more preferably not lower than 410°C); the air output by the first two air compressors first enters the heat exchanger of the molten salt storage and heat exchange system, and then enters the heat exchanger of the water storage and heat exchange system, and then is sent to the water cooler to be cooled to about 40°C (such as ±10°C), and then enters the next-stage air compressor; the compressed air output by the third air compressor directly enters the water cooler to be cooled to about 40°C (such as ±10°C) and then enters the artificial chamber storage system, or the compressed air output by the third air compressor is first supplied to the outside for heat, and then enters the water cooler to be cooled to about 40°C (such as ±10°C) and then enters the artificial chamber storage system.

[0054] Step S4: During peak electricity consumption, the artificial chamber storage system outputs compressed air to the expansion system. During the transportation process, the compressed air passes through the heat exchangers of the water storage heat exchange system and the molten salt storage heat exchange system in sequence, causing the temperature of the compressed air to increase. At the same time, the temperature of the heat storage medium in the heat exchangers of the water storage heat exchange system and the molten salt storage heat exchange system decreases. The heat storage medium in the two heat storage systems flows from their respective hot tanks through the heat exchangers into their respective cold tanks.

[0055] In step S5, a turbine expander at the end of the expansion system outputs air to drive a generator to generate electricity, and the output air is discharged into the atmosphere.

[0056] It is further preferred that the pressure in the turbine expansion system be no less than 7 MPa, the temperature be no less than 300°C (more preferably no less than 340°C), and the pressure fluctuation range be no less than 1 MPa (more preferably 2 MPa to 8 MPa); the pressure in the artificial chamber storage system be no less than 4 MPa, and the pressure fluctuation range be no less than 1 MPa. This high-temperature, high-pressure, and wide-pressure fluctuation range approach effectively reduces the required volume of the artificial chamber storage system and lowers system investment.

[0057] To sum up, the present invention is an artificial cavern compressed air energy storage system based on molten salt and water, which adopts wide-temperature molten salt + pressurized water as the heat storage and exchange medium, which can improve the energy storage and power generation efficiency of the system; the compressed air is compressed in three stages, which has higher energy storage efficiency, and the waste heat of the third-stage compressed air can also be used to provide heating for surrounding enterprises or residents; the artificial cavern is used as a gas storage reservoir to expand the flexibility of the site selection of the compressed air energy storage system; the artificial cavern with high pressure and large pressure fluctuation range, the artificial cavern storage system with high pressure and large pressure fluctuation range, and the turbine expansion system with high pressure, high temperature and large pressure fluctuation range can be used to effectively reduce the volume of the required artificial cavern, and the compressed air energy storage system using artificial cavern can be realized at a relatively low application cost.

Claims

1. An artificial chamber compressed air energy storage system based on molten salt and water, characterized in that: It includes an air compression system (A), an artificial chamber storage system (B) and an expansion system (C) connected in series, as well as a molten salt storage and heat exchange system (D) and a water storage and heat exchange system (E); The air compression system (A) includes one or more air compressors connected in series; the output pipeline of at least one air compressor passes through the heat exchanger and water cooler of the molten salt storage and heat exchange system (D) and the water storage and heat exchange system (E) in sequence, and is then connected to the input end of the downstream air compressor or the artificial chamber storage system (B); The expansion system (C) includes one or more turbine expanders connected in series; the output end pipeline of the artificial chamber storage system (B) passes through the heat exchangers of the water storage and heat exchange system (E) and the molten salt storage and heat exchange system (D) in sequence and is connected to the input end of the turbine expander downstream thereof; The molten salt heat storage and exchange system (D) comprises a salt storage cold tank (D5) and a salt storage hot tank (D6), wherein the output end of the salt storage cold tank (D5) is connected to the input end of the salt storage hot tank (D6) after passing through a first molten salt heat exchanger (D1) and a second molten salt heat exchanger (D2); the output end of the salt storage hot tank (D6) is connected to the input end of the salt storage cold tank (D5) after passing through a third molten salt heat exchanger (D3) and a fourth molten salt heat exchanger (D4); The water storage and heat exchange system (E) includes a cold water storage tank (E5) and a hot water storage tank (E6). The output end of the cold water storage tank (E5) is connected to the input end of the hot water storage tank (E6) through two pipelines passing through a first water heat exchanger (E1) and a second water heat exchanger (E2); the output end of the hot water storage tank (E6) is connected to the input end of the cold water storage tank (E5) through two pipelines passing through a third water heat exchanger (E3) and a fourth water heat exchanger (E4). The air compression system (A) includes a first-stage air compressor (A1), a second-stage air compressor (A2) and a third-stage air compressor (A3); The output end pipeline of the first-stage air compressor (A1) passes through the first molten salt heat exchanger (D1), the first water heat exchanger (E1) and the first water cooler (A4) in sequence, and is then connected to the input end of the second-stage air compressor (A2); the output end pipeline of the second-stage air compressor (A2) passes through the second molten salt heat exchanger (D2), the second water heat exchanger (E2) and the second water cooler (A5) in sequence, and is then connected to the input end of the third-stage air compressor (A3); the output end pipeline of the third-stage air compressor (A3) passes through the third water cooler (A6) and is then connected to the input end of the artificial chamber storage system (B); The air compressors in the air compression system (A) are all connected to a motor (M); the turbine expander at the end of the expansion system (C) is connected to a generator (G); The air compression system (A) is one set or multiple sets arranged in parallel.

2. The artificial cavern compressed air energy storage system based on molten salt and water according to claim 1, characterized in that: The expansion system (C) includes a first-stage turbine expander (C1) and a second-stage turbine expander (C2); The output end pipeline of the artificial cavern storage system (B) passes through the third water heat exchanger (E3) and the third molten salt heat exchanger (D3) in sequence and is connected to the input end of the first-stage turbine expander (C1); the output end pipeline of the first-stage turbine expander (C1) passes through the fourth water heat exchanger (E4) and the fourth molten salt heat exchanger (D4) in sequence and is connected to the input end of the second-stage turbine expander (C2).

3. A method for storing compressed air energy in an artificial chamber based on molten salt and water, characterized in that: The method is implemented based on the molten salt and water-based artificial cavern compressed air energy storage system according to any one of claims 1 to 2, comprising the following steps: During periods of low electricity consumption, redundant electricity is input into the air compression system. The air compressor in the air compression system draws in air for compression, increasing the temperature and pressure of the air. The compressed air output by the air compressor passes through the heat exchangers and water coolers of the molten salt heat storage and exchange system and the water storage and exchange system in sequence, reducing the temperature of the compressed air. At the same time, the temperature of the heat storage medium in the heat exchangers of the molten salt heat storage and exchange system and the water storage and exchange system increases. The heat storage medium in the two heat storage and exchange systems flows from their respective cold tanks through the heat exchangers into their respective hot tanks. The air compression system outputs compressed air to the artificial chamber storage system for storage; During peak electricity consumption, the artificial chamber storage system outputs compressed air to the expansion system. During the transportation process, the compressed air passes through the heat exchangers of the water storage heat exchange system and the molten salt storage heat exchange system in turn, causing the temperature of the compressed air to rise; at the same time, the temperature of the heat storage medium in the heat exchangers of the water storage heat exchange system and the molten salt storage heat exchange system decreases, and the heat storage medium in the two heat storage systems flows from their respective hot tanks through the heat exchangers into their respective cold tanks; The turbine expander at the end of the expansion system outputs air to drive a generator to generate electricity.

4. The method for storing compressed air in an artificial chamber based on molten salt and water according to claim 3, wherein: The operating temperature range of the molten salt, the heat storage medium in the molten salt heat storage and exchange system, is 150°C to 600°C, and the operating temperature range of the water, the heat storage medium in the water heat storage and exchange system, is 40°C to 185°C.

5. The method for storing compressed air energy in an artificial chamber based on molten salt and water according to claim 3 or 4, characterized in that: The air is compressed in three sections by three air compressors connected in series, and the air temperature at the output end of at least two air compressors is not lower than 340℃.

6. The method for storing compressed air energy in an artificial chamber based on molten salt and water according to claim 3 or 4, characterized in that: The pressure in the turbine expansion system shall not be lower than 7MPa, the temperature shall not be lower than 300℃, and the pressure fluctuation range shall not be lower than 1MPa; the pressure in the artificial chamber storage system shall not be lower than 4MPa, and the pressure fluctuation range shall not be lower than 1MPa.

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