Small and medium-sized compressed air energy storage system and compressed air energy storage method

Abstract

The invention relates to the technical field of energy storage, in particular to a small and medium-sized compressed air energy storage system and a compressed air energy storage method.The output end of a compression unit is connected with the first input end of a heat storage and exchange unit, and the first output end of the heat storage and exchange unit is connected with the input end of an air storage unit; the output end of the gas storage unit is connected with the second input end of the heat storage and exchange unit, and the second output end of the heat storage and exchange unit is connected with the input end of the expansion unit; the heat storage and exchange unit is a heat storage and exchange integrated heat accumulator used for absorbing heat of compressed air input from the first input end or heating high-pressure air input from the second input end. The compression unit and the expansion unit are coaxially arranged, and the input end of the compression unit and the output end of the expansion unit are connected with the generator motor. According to the energy storage system, heat storage and heat exchange are completed at the same time and at the same position through the heat storage and exchange unit, the heat storage and heat exchange process is simplified, and the compressed air energy storage system is more suitable for small and medium-sized air energy storage.

Description

Technical Field

[0001] The present application relates to the field of energy storage technology, and in particular to a small and medium-sized compressed air energy storage system and a compressed air energy storage method. Background Art

[0002] In order to meet energy demand, the world is accelerating the adjustment of energy structure and vigorously developing clean and renewable energy. Renewable energy such as wind and solar energy is intermittent and unstable, which poses a huge challenge to the safety and stability of the power grid. Energy storage technology is urgently needed to provide effective support for a strong and stable power grid and convert the unstable electricity generated by renewable energy into smooth and high-quality electricity that can be connected to the Internet. On the user side, the power load is uneven, especially the demand for electricity during the day and night is quite different. Therefore, energy storage technology can be used to store excess electricity during the low power consumption period, so as to release it during the peak power consumption period, so as to achieve the purpose of "peak shaving and valley filling" and improve the efficiency of conventional power systems.

[0003] Compressed-Air Energy Storage (CAES) has been promoted and applied as a new energy storage technology. It stores energy through a certain medium and then releases the stored energy when needed, thereby improving the efficiency, safety and economy of the energy system. However, the current compressed air energy storage system still faces problems such as large investment, large land area and complex system. This has greatly restricted the further development and application of compressed air energy storage systems, especially on the user side and small and medium-sized scales. Summary of the invention

[0004] In response to the above problems, the present application provides a small and medium-sized compressed air energy storage system and a compressed air energy storage method. By adopting a heat storage and exchange unit, heat storage and heat exchange are completed at the same time and location, which simplifies the heat storage and heat exchange process and makes the compressed air energy storage system more suitable for small and medium-sized air energy storage scenarios.

[0005] To achieve the purpose of this application, this application provides the following technical solutions:

[0006] In a first aspect, the present application provides a small and medium-sized compressed air energy storage system, comprising a compression unit, an expansion unit, a heat storage and exchange unit, and a gas storage unit; the output end of the compression unit is connected to the first input end of the heat storage and exchange unit, the first output end of the heat storage and exchange unit is connected to the input end of the gas storage unit, the output end of the gas storage unit is connected to the second input end of the heat storage and exchange unit, and the second output end of the heat storage and exchange unit is connected to the input end of the expansion unit.

[0007] The heat storage and exchange unit is a heat storage and exchange integrated heat accumulator including a cylinder and a heat storage material arranged in the cylinder, and is used to absorb the heat of the compressed air input from the first input end, or to heat the high-pressure air input from the second input end;

[0008] The central axis of the compression unit and the central axis of the expansion unit are coaxially arranged, and the input end of the compression unit and the output end of the expansion unit are detachably connected to the generator motor.

[0009] In a possible implementation, the heat storage material is a solid heat storage material, and the solid heat storage material is filled inside the cylinder based on a metal wire mesh.

[0010] In a possible implementation, the heat storage material is a molten salt phase change material, and the cylinder is arranged with a partition-type heat exchange pipeline; wherein each partition is filled with the molten salt phase change material, and multiple channels formed between the partitions are used to circulate air to complete heat exchange.

[0011] In a possible implementation manner, an anti-phase separation additive is added into the molten salt phase change material.

[0012] In a possible implementation, the compression unit is a single-stage compressor, and the expansion unit is a single-stage expander.

[0013] In a possible implementation, the compression unit includes at least two-stage compressors, and the expansion unit includes at least two-stage expanders; when the compression unit is a two-stage compressor and the expansion unit is a two-stage expander, the heat storage and exchange unit includes a first heat storage and exchange integrated heat accumulator and a second heat storage and exchange integrated heat accumulator; wherein, in the energy storage working stage, the medium and high pressure air at the outlet of the first-stage compressor sequentially passes through the first heat storage and exchange integrated heat accumulator, the second-stage compressor, and the second heat storage and exchange integrated heat accumulator, and is stored in the gas storage unit, and a compression circuit is formed when the gas storage unit is turned on; in the energy release working stage, the high pressure air at the outlet of the gas storage unit sequentially passes through the second heat storage and exchange integrated heat accumulator, the first-stage expander, the first heat storage and exchange integrated heat accumulator, and the second-stage expander, and an expansion circuit is formed when the gas storage unit is turned on. .

[0014] In a second aspect, the present application provides a small and medium-sized compressed air energy storage system, including a compression and expansion dual-purpose integrated device, a heat storage and exchange unit, and an air storage unit;

[0015] The compression-expansion dual-purpose integrated device comprises a movable scroll and a fixed scroll; when the compression-expansion dual-purpose integrated device is in the energy storage working stage, the movable scroll rotates under the drive of the prime mover, sucks gas from the air inlet, and then the gas enters the compression chamber and the exhaust chamber in sequence, and the compressed gas is discharged through the central air hole after the compression is completed; when the compression-expansion dual-purpose integrated device is in the energy release working stage, the high-pressure gas enters through the central air hole, expands in the closed chamber formed by the movable scroll and the fixed scroll, and then outputs through the main shaft power;

[0016] The central air hole of the compression and expansion dual-purpose integrated device is connected to the first input end of the heat storage and exchange unit based on the energy storage pipeline, the first output end of the heat storage and exchange unit is connected to the input end of the gas storage unit, the output end of the gas storage unit is connected to the second input end of the heat storage and exchange unit, and the second output end of the heat storage and exchange unit is connected to the central air hole based on the energy release pipeline;

[0017] The heat storage and exchange unit is a heat storage and exchange integrated heat accumulator including a cylinder and a heat storage material arranged in the cylinder, and is used to absorb the heat of the compressed air input from the first input end, or to heat the high-pressure air input from the second input end;

[0018] The generator motor is connected to the compression-expansion dual-purpose integrated device shaft, and is used to provide electrical energy to the compression-expansion dual-purpose integrated device in the energy storage working stage, or to generate electrical energy based on the output power from the compression-expansion dual-purpose integrated device in the energy release working stage.

[0019] In a possible embodiment, the heat storage material is a solid heat storage material, and the solid heat storage material is filled inside the cylinder based on a metal wire mesh, or the heat storage material is a molten salt phase change material, and a partition-type heat exchange pipeline is arranged inside the cylinder; wherein the molten salt phase change material is filled inside each partition, and a plurality of channels formed between each partition are used to circulate air to complete heat exchange.

[0020] In a third aspect, the present application provides an electric power system, comprising a power grid and any of the above-mentioned small and medium-sized compressed air energy storage systems, wherein the generator motor in the compressed air energy storage system is electrically connected to the power grid.

[0021] In a fourth aspect, the present application provides a compressed air energy storage method, which is applied to the above-mentioned small and medium-sized compressed air energy storage system, and the method includes:

[0022] In the energy storage working stage, the compressed air output from the output end of the compression unit completes heat exchange and heat storage in the heat storage and exchange unit, and is then stored in the air storage unit for air energy storage;

[0023] During the energy release working stage, the high-pressure air stored in the gas storage unit is input into the heat storage and exchange unit, so that the heat storage and exchange unit heats the high-pressure gas to obtain heated high-pressure gas, and the heated high-pressure gas is input into the expansion unit for expansion work output.

[0024] The small and medium-sized compressed air energy storage system and compressed air energy storage method provided by this application combine heat exchange and heat storage, and replace heat exchangers and heat storage tanks with integrated heat storage and exchange accumulators, effectively reducing system processes and equipment investment and land occupation, making the compressed air energy storage system more suitable for small and medium-sized energy storage needs. At the same time, by arranging the central axis of the compression unit and the central axis of the expansion unit coaxially, the structure of the compressed air energy storage system is more compact, greatly reducing land costs and equipment costs. Under the same scale, the area occupied by the compressed air energy storage system of this scheme (excluding the gas storage unit) can be reduced by about 50% compared with the area occupied by traditional compressed air energy storage (excluding the gas storage unit). BRIEF DESCRIPTION OF THE DRAWINGS

[0025] The accompanying drawings are used to provide a further understanding of the present application and form a part of the specification. Together with the embodiments of the present application, they are used to explain the present application and do not constitute a limitation to the present application.

[0026] Figure 1 A flow chart of a typical compressed air energy storage system provided in an embodiment of the present application;

[0027] Figure 2 A schematic diagram of the structure of a small and medium-sized compressed air energy storage system provided in an embodiment of the present application;

[0028] Figure 3 An optional structural schematic diagram of a heat storage and exchange integrated heat accumulator for a small and medium-sized compressed air energy storage system provided in an embodiment of the present application;

[0029] Figure 4 An optional structural schematic diagram of a heat storage and exchange integrated heat accumulator for a small and medium-sized compressed air energy storage system provided in an embodiment of the present application;

[0030] Figure 5 A schematic diagram of the structure of a small and medium-sized compressed air energy storage system provided in an embodiment of the present application.

[0031] Reference numerals:

[0032] 1. Compression unit; 2. Expansion unit; 3. Heat storage and exchange unit; 4. Gas storage unit; 5. Generator motor; 11. First-stage compressor; 12. Second-stage compressor; 13. First valve; 14. Second valve; 15. Third valve; 21. First-stage expander; 22. Second-stage expander; 23. Fourth valve; 24. Fifth valve; 25. Sixth valve; 31. First heat storage and exchange integrated heat accumulator; 32. Second heat storage and exchange integrated heat accumulator. DETAILED DESCRIPTION

[0033] In order to make the purpose, technical solutions and advantages of this application clearer, the technical solutions in this application will be clearly and completely described below in conjunction with the drawings in this application. Obviously, the described embodiments are part of the embodiments of this application, not all of them. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0034] The terms "first" and "second" are used for descriptive purposes only and should not be understood as indicating or implying relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features; in the description of this application, unless otherwise specified, "plurality" means two or more.

[0035] The compressed air energy storage system is an electric energy storage system that can achieve large-capacity and long-term electrical energy storage. It compresses air through a compressor during low-load periods of the grid, converts excess electrical energy into pressure energy and heat energy, and expands and performs work through an expander during high-load periods of the grid, driving a generator to generate electricity. Figure 1 This is a typical flow chart of compressed air energy storage system. Figure 1 As shown, the system mainly includes a compression unit, a heat exchange unit, a heat storage unit, a gas storage unit, an expansion unit, a power generation unit, etc., and its working process is mainly divided into an energy storage stage and an energy release stage.

[0036] Energy storage stage: The air is compressed by a compressor. The compression process is often a multi-stage compression and inter-stage heat exchange cooling method. One side of the inter-stage heat exchanger is compressed air, and the other side is a heat storage medium. The heat storage medium usually uses water, heat transfer oil or molten salt. After the heat storage medium obtains the heat energy of the compressed air, it is transported to the high-temperature heat storage tank through a pipeline. The compressed air is cooled by the inter-stage heat exchanger and then enters the next stage compressor and is finally stored in the gas storage.

[0037] Energy release stage: High-pressure air is released from the gas storage, heated by the reheater (regenerator), and then enters the expander to expand and drive the generator to generate electricity. The expansion process often adopts multi-stage expansion and inter-stage reheating. One side of the interstage is air, and the other side is the heat storage medium from the high-temperature heat storage tank. The heat storage medium is transported to the inter-stage reheater (regenerator) for heat exchange. This process will release the heat energy from the compression stage to the air through the reheater (regenerator), which is used to increase the expansion work and improve the electricity-to-electricity conversion efficiency of the entire system. The heat storage medium after heat exchange is transported to the low-temperature heat storage tank (the heat storage medium in the compression stage flows out of the low-temperature heat storage tank again, enters the inter-stage heat exchanger of the compression unit to obtain compression heat, and then flows back to the high-temperature heat storage tank, forming a cycle); the high-pressure air is finally discharged into the atmosphere after multi-stage expansion.

[0038] However, the current compressed air energy storage system still faces problems such as large investment, large space, and complex system. This has greatly restricted the further development and application of compressed air energy storage systems, especially on the user side and on a small and medium-sized scale.

[0039] In order to solve the above technical problems, the present invention proposes the following technical solutions and corresponding embodiments.

[0040] Example 1

[0041] Combine the following Figures 2 to 5 The embodiments shown describe the technical solution of the present invention:

[0042] Figure 2 A schematic diagram of the structure of a small and medium-sized compressed air energy storage system according to an embodiment of the present application is shown. Figure 2 As shown, the small and medium-sized compressed air energy storage system of the embodiment of the present application includes: a compression unit 1, an expansion unit 2, a heat storage and exchange unit 3 and an air storage unit 4; the output end of the compression unit 1 is connected to the first input end of the heat storage and exchange unit 3, the first output end of the heat storage and exchange unit 3 is connected to the input end of the air storage unit 4, the output end of the air storage unit 4 is connected to the second input end of the heat storage and exchange unit 3, and the second output end of the heat storage and exchange unit 3 is connected to the input end of the expansion unit 2; the central axis of the compression unit 1 and the central axis of the expansion unit 2 are coaxially arranged, and the input end of the compression unit 1 and the output end of the expansion unit 2 are detachably connected to the generator motor 5.

[0043] In the embodiment of the present application, the heat storage and exchange unit 3 is a heat storage and exchange integrated heat storage device including a cylinder and a heat storage material disposed in the cylinder, which is used to absorb the heat of the compressed air input from the first input end, or to heat the high-pressure air input from the second input end. Figure 2As shown, in the energy storage working stage of the system, after the valve on the compression unit 1 side is opened and the clutch is connected, the air is compressed by the compressor of the compression unit 1 and then enters the integrated heat storage and exchanger accumulator, and the high-temperature and high-pressure air flows through the integrated heat storage and exchanger accumulator, and is gradually cooled by the heat storage material in the integrated heat storage and exchanger accumulator and then stored in the gas storage unit 4, and the integrated heat storage and exchanger accumulator stores the heat energy in the high-temperature and high-pressure air through the heat storage material to achieve heat storage; in the energy release working stage of the system, the valve on the expansion unit 2 side is opened and the clutch is connected, and the high-pressure air flows out of the gas storage reservoir and enters the integrated heat storage and exchanger accumulator, and after being gradually heated by the heat released by the heat storage material in the integrated heat storage and exchanger accumulator, it enters the expander of the expansion unit, prompting the expander to do work, thereby driving the generator motor 5 to generate electricity. In the embodiment of the present application, refer to Figure 3 As shown, the heat storage and exchange integrated heat accumulator is a long cylinder type, and the heat storage material can be a solid heat storage material, which is completely filled in the cylinder based on a preset porosity, wherein the axial direction of the long cylinder is parallel to the flow direction of the high-temperature and high-pressure air, that is, during the operation of the heat storage and exchange integrated heat accumulator, along the flow direction of the high-temperature and high-pressure air, its temperature presents a gradient from high to low. Exemplarily, the solid heat storage material can be quartz stone filled and arranged based on a metal mesh.

[0044] As a feasible implementation method, in addition to filling the cylinder with solid heat storage material and allowing the air entering the cylinder to circulate through the pores, the heat storage material can also be a molten salt phase change material: Reference Figure 4 As shown, a partition-type heat exchange pipeline is arranged in the cylinder; wherein each partition is filled with molten salt phase change material, and multiple channels formed between the partitions are used to circulate air to complete heat exchange, and the axis of the multiple channels is parallel to the axial direction of the cylinder to facilitate air circulation to complete heat exchange. Here, in order to ensure that the phase change material does not separate and affect the heat storage and heat release performance of the integrated heat storage and exchanger, an anti-phase separation additive is added to the molten salt phase change material.

[0045] In the embodiment of the present application, when compressed air flows into the gas storage reservoir, the molten salt phase change material inside the heat storage and exchange integrated accumulator absorbs thermal energy in the air. Since the thermal energy in the air is continuously absorbed by the molten salt phase change material, when the phase change temperature is reached, the phase change material undergoes a phase change, absorbs and stores heat, and increases the heat storage per unit volume, thereby lowering the air temperature. When high-pressure air flows out of the gas storage reservoir, the high-pressure air continuously absorbs the thermal energy stored in the phase change material when flowing through the heat storage and exchange integrated accumulator, and is continuously heated by the heat storage and exchange integrated accumulator, thereby allowing the thermal energy stored in the energy storage stage to be utilized in the energy release stage.

[0046] Exemplarily, the molten salt phase change material of the present application is sodium sulfate decahydrate.

[0047] In the embodiment of the present application, the generator motor 5 is coaxially connected to the compression unit 1 through the first clutch, and the generator motor 5 is coaxially connected to the expansion unit 2 through the second clutch. When the small and medium-sized compressed air energy storage system is in the energy storage working stage, the generator motor is switched to the motor mode, and the first clutch makes the generator motor 5 coaxially connected to the compressor of the compression unit 1 and disconnected from the expander of the expansion unit 2; the filtered ambient air is compressed by the compression unit 1 and then outputs the compressed air, which is input into the heat storage and exchange integrated accumulator for heat absorption and storage, and then the compressed air that absorbs the heat is discharged into the gas storage unit 4 for storage. Exemplarily, the gas storage unit 4 can be a gas storage reservoir / gas storage chamber. When the small and medium-sized compressed air energy storage system is in the energy release working stage, the generator motor 5 is switched to the generator mode, and the second clutch makes the generator motor 5 coaxially connected to the expander of the expansion unit 2 and disconnected from the compressor of the compression unit 1; the high-pressure air released from the gas storage reservoir / gas storage chamber enters the heat storage and exchange integrated accumulator for heating, and then enters the expander for expansion and work, driving the generator motor 5 to generate electricity. Here, the generator motor 5 can be replaced by a generator and an electric motor, the first clutch and the second clutch are removed, the generator is directly connected to the expansion unit coaxially, and the electric motor is directly connected to the compression unit coaxially, wherein the electric motor is one or more, that is, one electric motor drives one compressor or one electric motor drives multiple compressors. By using different numbers of electric motors to drive the compressor, the amount of electric energy absorbed can be changed to better meet the requirements of grid frequency regulation.

[0048] In the embodiment of the present application, the compressor of the compression unit and the expander of the expansion unit may be arranged in a single stage.

[0049] It should be noted that, in order to improve the energy storage efficiency, the small and medium-sized compressed air energy storage system of the present application can be equipped with two or more compressors and expanders in the compression unit 1 and the expansion unit 2, where the number of compressors and expanders is the same. Figure 5As shown, in the case where the compression unit 1 of the small and medium-sized compressed air energy storage system is a two-stage compressor and the expansion unit 2 is a two-stage expander, the heat storage and exchange unit 3 adopts a first heat storage and exchange integrated heat accumulator and a second heat storage and exchange integrated heat accumulator; wherein, in the energy storage working stage, the first valve 13, the second valve 14 and the third valve 15 are opened, and the fourth valve 23, the fifth valve 24 and the sixth valve 25 are closed, and the medium and high pressure air at the outlet of the first stage compressor 11 passes through the first heat storage and exchange integrated heat accumulator 31, the second stage compressor 12, and the second heat storage and exchange integrated heat accumulator 32 in sequence, and is stored in the gas storage unit 4, and a compression loop is formed when it is turned on; in the energy release working stage, the fourth valve 23, the fifth valve 24 and the sixth valve 25 are opened, the first valve 13, the second valve 14 and the third valve 15 are closed, and the high pressure air at the outlet of the gas storage unit 4 passes through the second heat storage and exchange integrated heat accumulator 32, the first stage expander 21, the first heat storage and exchange integrated heat accumulator 31, and the second stage expander 22 in sequence, and an expansion loop is formed when it is turned on.

[0050] The small and medium-sized compressed air energy storage system provided by this application combines heat exchange and heat storage, and replaces heat exchangers, heat storage tanks and other equipment with integrated heat storage and exchange accumulators, which effectively reduces the system process and equipment investment and land occupation, making the compressed air energy storage system more meet the power storage needs of small power stations and industrial park microgrids and other small and medium-sized scenarios. At the same time, by arranging the central axis of the compression unit and the central axis of the expansion unit coaxially, the structure of the compressed air energy storage system is more compact, greatly reducing land costs and equipment costs. Under the same scale, the area occupied by the compressed air energy storage system of this scheme (excluding the gas storage unit) can be reduced by about 50% compared with the area occupied by traditional compressed air energy storage (excluding the gas storage unit).

[0051] Example 2

[0052] Based on the foregoing embodiments, the embodiments of the present application further provide a small and medium-sized compressed air energy storage system, wherein the compression unit and the expansion unit are completed by a compression and expansion dual-purpose integrated device, wherein the compression and expansion dual-purpose integrated device is a turbine compression expander, including a movable scroll and a static scroll; when the compression and expansion dual-purpose integrated device is in the energy storage working stage, the movable scroll rotates under the drive of the prime mover, and the gas is sucked in from the air inlet, and then the gas enters the compression chamber and the exhaust chamber in sequence, and the compressed gas is discharged through the central air hole after the compression is completed; when the compression and expansion dual-purpose integrated device is in the energy release working stage, the high-pressure gas enters through the central air hole, expands in the closed chamber composed of the movable scroll and the static scroll, and then outputs through the main shaft power;

[0053] In the embodiment of the present application, the central air hole of the compression and expansion dual-purpose integrated device is connected to the first input end of the heat storage and exchange unit based on the energy storage pipeline, the first output end of the heat storage and exchange unit is connected to the input end of the gas storage unit, the output end of the gas storage unit is connected to the second input end of the heat storage and exchange unit, and the second output end of the heat storage and exchange unit is connected to the central air hole based on the energy release pipeline;

[0054] Similarly, the heat storage and exchange unit in the embodiment of the present application can be an integrated heat storage and exchange accumulator, which includes a cylinder and a heat storage material arranged in the cylinder, and is used to absorb the heat of the compressed air input from the first input end, or to heat the high-pressure air input from the second input end.

[0055] In an embodiment of the present application, a generator motor is connected to the compression and expansion dual-purpose integrated device shaft to provide electrical energy to the compression and expansion dual-purpose integrated device in the energy storage working stage, or to generate electrical energy based on the output power from the compression and expansion dual-purpose integrated device in the energy release working stage.

[0056] In this way, by replacing the two sets of equipment, the compression unit and the expansion unit, with a compression and expansion dual-purpose device, the process is greatly simplified, the energy storage efficiency is improved and the equipment cost is further reduced.

[0057] Based on the foregoing embodiments, an embodiment of the present application further provides a power system, including a power grid and the above-mentioned small and medium-sized compressed air energy storage system, wherein the generator motor in the small and medium-sized compressed air energy storage system is electrically connected to the power grid.

[0058] The above embodiments are only used to illustrate the technical solution of the present application, but not to limit it. The present application is not limited to the exact structure described above and illustrated in the accompanying drawings, and it cannot be determined that the specific implementation of the present application is limited to these descriptions. For ordinary technicians in the technical field to which the present application belongs, various changes and modifications made without departing from the concept of the present application should be deemed to belong to the protection scope of the present application.

[0059] In the several embodiments provided in the present application, it should be understood that the disclosed systems, modules and methods can be implemented in other ways. For example, the module embodiments described above are only schematic, for example, the division of units is only a logical function division, and there may be other division methods in actual implementation, such as multiple units or components can be combined or integrated into another system, or some features can be ignored or not executed. Another point is that the mutual coupling or direct coupling or communication connection shown or discussed can be an indirect coupling or communication connection through some interfaces, modules or units, which can be electrical, mechanical or other forms.

[0060] The above embodiments are only used to illustrate the technical solution of the present application, but not to limit it. The present application is not limited to the exact structure described above and illustrated in the accompanying drawings, and it cannot be determined that the specific implementation of the present application is limited to these descriptions. For ordinary technicians in the technical field to which the present application belongs, various changes and modifications made without departing from the concept of the present application should be deemed to belong to the protection scope of the present application.

Claims

1. A small and medium-sized compressed air energy storage system, characterized in that: The invention comprises a compression unit (1), an expansion unit (2), a heat storage and exchange unit (3) and a gas storage unit (4); the output end of the compression unit (1) is connected to the first input end of the heat storage and exchange unit (3), the first output end of the heat storage and exchange unit (3) is connected to the input end of the gas storage unit (4), the output end of the gas storage unit (4) is connected to the second input end of the heat storage and exchange unit (3), and the second output end of the heat storage and exchange unit (3) is connected to the input end of the expansion unit (2); The heat storage and exchange unit (3) is a heat storage and exchange integrated heat accumulator comprising a cylinder and a heat storage material arranged in the cylinder, and is used to absorb the heat of the compressed air input from the first input end, or to heat the high-pressure air input from the second input end; The central axis of the compression unit (1) and the central axis of the expansion unit (2) are coaxially arranged, and the input end of the compression unit (1) and the output end of the expansion unit (2) are detachably connected to the generator motor (5).

2. The small and medium-sized compressed air energy storage system according to claim 1, characterized in that: The heat storage material is a solid heat storage material, and the solid heat storage material is filled inside the cylinder based on a metal wire mesh.

3. The small and medium-sized compressed air energy storage system according to claim 1, characterized in that: The heat storage material is a molten salt phase change material; The cylinder is arranged with partition-type heat exchange pipelines; wherein each partition is filled with the molten salt phase change material, and a plurality of channels formed between the partitions are used to circulate air to complete heat exchange.

4. The small and medium-sized compressed air energy storage system according to claim 3 is characterized in that: An anti-phase separation additive is added into the molten salt phase change material.

5. The small and medium-sized compressed air energy storage system according to any one of claims 2 to 4, characterized in that: The compression unit (1) is a single-stage compressor, and the expansion unit (2) is a single-stage expander.

6. The small and medium-sized compressed air energy storage system according to any one of claims 2 to 4, characterized in that: The compression unit (1) comprises at least two stages of compressors, and the expansion unit (2) comprises at least two stages of expanders; When the compression unit (1) is a two-stage compressor and the expansion unit (2) is a two-stage expander, the heat storage and exchange unit (3) comprises a first heat storage and exchange integrated heat accumulator (31) and a second heat storage and exchange integrated heat accumulator (32); In the energy storage working stage, the medium and high pressure air at the outlet of the first-stage compressor (11) passes through the first integrated heat storage and exchange accumulator (31), the second-stage compressor (12), and the second integrated heat storage and exchange accumulator (32) in sequence, and is stored in the gas storage unit (4), forming a compression circuit when it is turned on; in the energy release working stage, the high pressure air at the outlet of the gas storage unit (4) passes through the second integrated heat storage and exchange accumulator (32), the first-stage expansion machine (21), the first integrated heat storage and exchange accumulator (31), and the second-stage expansion machine (22) in sequence, forming an expansion circuit when it is turned on.

7. A small and medium-sized compressed air energy storage system, characterized in that: It includes a compression and expansion dual-purpose integrated device, a heat storage and exchange unit and a gas storage unit; The compression-expansion dual-purpose integrated device comprises a movable scroll and a fixed scroll; when the compression-expansion dual-purpose integrated device is in the energy storage working stage, the movable scroll rotates under the drive of the prime mover, sucks gas from the air inlet, and then the gas enters the compression chamber and the exhaust chamber in sequence, and the compressed gas is discharged through the central air hole after the compression is completed; when the compression-expansion dual-purpose integrated device is in the energy release working stage, the high-pressure gas enters through the central air hole, expands in the closed chamber formed by the movable scroll and the fixed scroll, and then outputs through the main shaft power; The central air hole of the compression-expansion dual-purpose integrated device is connected to the first input end of the heat storage and exchange unit (3) based on the energy storage pipeline, the first output end of the heat storage and exchange unit (3) is connected to the input end of the gas storage unit (4), the output end of the gas storage unit (4) is connected to the second input end of the heat storage and exchange unit (3), and the second output end of the heat storage and exchange unit (3) is connected to the central air hole based on the energy release pipeline; The heat storage and exchange unit (3) is a heat storage and exchange integrated heat accumulator comprising a cylinder and a heat storage material arranged in the cylinder, and is used to absorb the heat of the compressed air input from the first input end, or to heat the high-pressure air input from the second input end; The generator motor (5) is connected to the compression and expansion dual-purpose integrated device shaft and is used to provide electric energy to the compression and expansion dual-purpose integrated device in the energy storage working stage, or to generate electric energy based on the output power from the compression and expansion dual-purpose integrated device in the energy release working stage.

8. The small and medium-sized compressed air energy storage system according to claim 7, characterized in that: The heat storage material is a solid heat storage material, and the solid heat storage material is filled inside the cylinder based on a metal wire mesh. Alternatively, the heat storage material is a molten salt phase change material, and the cylinder is arranged with a partition-type heat exchange pipeline; wherein each partition is filled with the molten salt phase change material, and a plurality of channels formed between the partitions are used to circulate air to complete heat exchange.

9. A power system, characterized in that: It comprises a power grid and the small and medium-sized compressed air energy storage system described in any one of claims 1 to 6 or the small and medium-sized compressed air energy storage system described in any one of claims 7 to 8, wherein the generator motor in the compressed air energy storage system is electrically connected to the power grid.

10. A compressed air energy storage method, applied to the small and medium-sized compressed air energy storage system according to any one of claims 1 to 6, characterized in that: include: In the energy storage working stage, the compressed air output from the output end of the compression unit (1) completes heat exchange and heat storage in the heat storage and exchange unit (3) and is then stored in the air storage unit (5) to perform air energy storage; During the energy release working stage, the high-pressure air stored in the gas storage unit (4) is input into the heat storage and exchange unit (3), so that the heat storage and exchange unit (3) heats the high-pressure gas to obtain heated high-pressure gas, and the heated high-pressure gas is input into the expansion unit (2) to perform expansion work output.

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