Compressed air energy storage system

Abstract

The utility model discloses a compressed air energy storage system, which comprises a constant-pressure diaphragm air pressure tank, an air compression energy release subsystem and a constant-pressure working medium gas gas-liquid conversion subsystem, and has the advantages that two heat exchangers are adopted on the constant-pressure working medium gas gas-liquid conversion subsystem to accelerate the working medium gas gas-liquid conversion efficiency; the conversion of air and working medium gas in the constant-pressure diaphragm air pressure tank is accelerated, so that the energy storage efficiency or the energy release efficiency is correspondingly improved; air is adopted as a main medium for compression expansion power generation, working medium gas serves as a medium with stable pressure and does not participate in acting, alternation of the air and the working medium gas in the tank is completed through gas film contraction / expansion, and the pressure stabilizing effect of the two stages of energy storage and energy release is achieved; air is adopted for compression and expansion power generation at the energy storage and release end, a carbon dioxide large-scale air storage bin at the traditional carbon dioxide energy storage low-pressure end is eliminated and replaced with inexhaustible natural air, and the air is directly discharged into the atmosphere at the energy release stage, so that the equipment cost and the medium cost are greatly reduced.

Description

Technical Field

[0001] This utility model relates to the field of energy storage system technology, specifically a compressed air energy storage system. Background Technology

[0002] Compressed air energy storage technology is a physical energy storage technology that uses compressed air to store energy. It has advantages such as large energy storage capacity, high safety, economic efficiency, environmental friendliness, and technological maturity. It plays an important role in future energy systems, especially in promoting the use of renewable energy and improving grid stability.

[0003] Carbon dioxide energy storage (CES) technology is a novel physical energy storage technology based on compressed air energy storage (CAES) and the Brayton cycle. As a new technology, CES utilizes off-peak electricity prices to convert atmospheric gaseous carbon dioxide into high-pressure liquid carbon dioxide via a multi-stage compressor, storing electrical energy as the internal energy of the carbon dioxide. During peak electricity demand periods, a multi-stage expander expands the high-pressure liquid carbon dioxide back into atmospheric gaseous carbon dioxide for power generation, ultimately achieving the storage and release of electrical energy. However, this system has some drawbacks: ① Huge equipment investment. The entire system comprises a low-pressure gas storage chamber, a high-pressure storage tank, a compressor unit, a turbine unit, a heat exchange system, and numerous cold and heat storage tanks. The low-pressure gas storage chamber, in particular, uses atmospheric pressure to store carbon dioxide. For example, a 10MW CES system would require a 1 million cubic meter low-pressure storage chamber, representing a significant land cost in developed regions. The investment costs for these systems are substantial, and the cost of technology promotion cannot be ignored, requiring improvement. Utility Model Content

[0004] One of the technical problems this application aims to solve is to overcome the shortcomings of the above-mentioned related technologies and provide an energy storage form that optimizes the traditional single-medium low-pressure storage of carbon dioxide energy storage and compressed air energy storage, replacing it with a new type of compressed air energy storage system that combines compressed air and compressed working gas with lightweight equipment and high energy storage efficiency.

[0005] The technical solution adopted by this utility model to solve the technical problem is as follows: a compressed air energy storage system, including a constant pressure diaphragm pressure tank, an air compression and energy release subsystem, and a constant pressure working gas gas-liquid conversion subsystem. The constant pressure diaphragm pressure tank is divided into a first cavity and a second cavity by a gas membrane, and the pressure of the second cavity is the same as that of the first cavity. The first cavity is connected to the air compression and energy release subsystem, which is used to inject compressed air into the first cavity during the energy storage stage and to discharge the compressed air in the first cavity during the energy release stage. The second cavity is connected to the constant pressure working gas gas-liquid conversion subsystem.

[0006] The constant pressure working gas gas-liquid conversion subsystem mainly consists of a working gas storage tank, heat exchanger C, heat exchanger D, a cold source and a heat source. The working gas storage tank is connected to heat exchanger C, heat exchanger D and the second cavity in sequence through pipelines.

[0007] The constant pressure working gas gas-liquid conversion subsystem is used in the energy storage stage. The working gas discharged from the second cavity sequentially passes through heat exchanger D and heat exchanger C to absorb the cold energy provided by the cold source, liquefies it, and then flows into the working gas storage tank.

[0008] The constant-pressure working gas gas-liquid conversion subsystem is used in the energy release stage. The liquid working gas flowing out of the working gas storage tank is vaporized by absorbing heat energy provided by the heat source through heat exchangers C and D in sequence and then discharged into the second cavity.

[0009] Compared with related technologies, this utility model has the following advantages: The constant-pressure working gas gas-liquid conversion subsystem employs two heat exchangers to accelerate the working gas-liquid conversion efficiency and expedite the conversion between air and working gas within the constant-pressure diaphragm pressure tank, thereby correspondingly improving energy storage efficiency or energy release efficiency. Simultaneously, two energy storage media are used: air serves as the primary medium for compression and expansion power generation, while the working gas, as a pressure-stable medium, does not participate in work. The alternation of the two media, air and working gas, within the tank is achieved through gas film contraction / expansion, realizing a pressure-stabilizing effect in both energy storage and energy release stages. At the energy storage and energy release end, air is used for compression and expansion power generation. Compared to traditional carbon dioxide energy storage, this eliminates the need for a large carbon dioxide storage chamber at the low-pressure end of traditional carbon dioxide energy storage, replacing it with inexhaustible natural air. During the energy release stage, the air is directly emitted into the atmosphere, significantly reducing equipment costs, land costs, and medium costs at the low-pressure gas storage end.

[0010] Preferably, the cold source is a cold storage tank and a refrigeration unit. The cold storage tank is connected to the heat exchange pipelines of heat exchangers C and D via the refrigeration unit. The cold storage tank and the refrigeration unit are used to sequentially provide cold energy to heat exchangers C and D. This is used to coordinate the working efficiency of heat exchangers C and D, thereby accelerating the replacement of the compressed working gas by the compressed air in the constant pressure diaphragm pressure tank, and thus correspondingly improving the energy storage efficiency.

[0011] Preferably, the heat source is a high-pressure heat storage tank A and a heat storage tank C; the high-pressure heat storage tank A is connected to the heat exchange pipeline of heat exchanger C and heat exchanger D, and is used to sequentially provide heat energy to heat exchanger D and heat exchanger C; the heat storage tank C is connected to the heat exchange branch between heat exchanger C and heat exchanger D, and is used to provide heat energy to heat exchanger C. This is used to coordinate with the working efficiency of heat exchanger C and heat exchanger D, to accelerate the replacement of compressed air with compressed working gas in the constant pressure diaphragm pressure tank, thereby correspondingly improving the energy release efficiency.

[0012] Preferably, the pressure inside the first cavity of the constant pressure diaphragm pressure tank is 1.5~15 MPa. Compared with the atmospheric pressure gas chamber, the constant pressure diaphragm pressure tank reduces the occupied volume by 15~150 times, greatly reducing the land use cost.

[0013] As an improvement, the pressure in the first cavity of the constant-pressure diaphragm pressure tank is 6 MPa, the working gas is carbon dioxide, and the second cavity is located inside the first cavity. Utilizing the physical property that carbon dioxide liquefies at 22°C under 6 MPa, the volume changes resulting from the vaporization and liquefaction of carbon dioxide are used to achieve pressure balance amidst changes in compressed air within the constant-pressure diaphragm pressure tank. This solves the risk of high-pressure alternating pressure operation in the constant-pressure diaphragm pressure tank, thereby achieving a new energy storage model characterized by miniaturization, lightweight equipment, high-quality energy storage, and greater flexibility.

[0014] Preferably, the air compression energy release subsystem includes an air compression component, an air energy release component, and a heat exchange circulation mechanism mainly composed of a high-pressure heat storage tank A, a cold storage tank, and a heat storage tank C. The heat exchange circulation mechanism is also used to provide the heat energy released by the air compression component in the energy storage stage to the air energy release component in the energy release stage. This reduces the number of cold and hot tanks and lowers equipment costs. Attached Figure Description

[0015] Figure 1 This is a connection diagram of the compressed air energy storage system of this application. Detailed Implementation

[0016] First, those skilled in the art should understand that these embodiments are merely used to explain the technical principles of the embodiments of this application and are not intended to limit the scope of protection of the embodiments of this application. Those skilled in the art can make adjustments as needed to adapt to specific application scenarios.

[0017] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0018] This preferred embodiment is as follows: Figure 1 The compressed air energy storage system shown includes a constant-pressure diaphragm pressure tank, an air compression and energy release subsystem, and a constant-pressure working gas gas-liquid conversion subsystem.

[0019] The constant pressure diaphragm pressure tank is divided into a first cavity and a second cavity by a gas membrane. The pressure in the first cavity and the second cavity is the same and remains constant.

[0020] The first cavity is connected to an air compression and energy release subsystem, which is used to store compressed air into the first cavity during the energy storage phase and to discharge the compressed air from the first cavity during the energy release phase.

[0021] The second cavity is connected to the constant pressure working gas gas-liquid conversion subsystem. The constant pressure working gas gas-liquid conversion subsystem mainly consists of a working gas storage tank, heat exchanger C, heat exchanger D, cold source and heat source. The working gas storage tank is connected to heat exchanger C, heat exchanger D and the second cavity in sequence through pipelines.

[0022] The constant pressure working gas gas-liquid conversion subsystem is used in the energy storage stage. The working gas discharged from the second cavity sequentially passes through heat exchanger D and heat exchanger C to absorb the cold energy provided by the cold source, liquefies it, and then flows into the working gas storage tank.

[0023] The constant-pressure working gas gas-liquid conversion subsystem is used in the energy release stage. The liquid working gas flowing out of the working gas storage tank is vaporized by absorbing heat energy provided by the heat source through heat exchangers C and D in sequence and then discharged into the second cavity.

[0024] In this embodiment, the cold source is a cold storage tank and a refrigeration unit. The cold storage tank is connected to the heat exchange pipelines of heat exchanger C and heat exchanger D through the refrigeration unit. The cold storage tank and the refrigeration unit are used to provide cold energy to heat exchanger C and heat exchanger D in sequence.

[0025] In this embodiment, the heat source is a high-pressure heat storage tank A and a heat storage tank C; the high-pressure heat storage tank A is connected to the heat exchange pipeline of heat exchanger C and heat exchanger D, and the high-pressure heat storage tank A is used to provide heat energy to heat exchanger D and heat exchanger C in sequence; the heat storage tank C is connected to the heat exchange branch between heat exchanger C and heat exchanger D, and the heat storage tank C is used to provide heat energy to heat exchanger C.

[0026] Specifically, during the energy storage phase, the gaseous working fluid discharged from the second cavity liquefies the cold energy from the cold storage tank and the refrigeration unit through heat exchangers D and C, and then flows into the working fluid gas storage tank. During the energy release phase, the liquid working fluid gas flowing out of the storage tank vaporizes the heat energy from the high-pressure heat storage tank A and the heat storage tank C through heat exchangers C and D, and then flows into the second cavity. The liquefaction and vaporization of the working fluid gas balance the volume changes of compressed air during the energy storage and release phases. The gas film flexibly deforms with the changes in the amount of air and working fluid stored, and the corresponding changes in the volume of the first and second cavities cause the gas film to contract / expand, maintaining a constant pressure inside the constant-pressure diaphragm pressure tank.

[0027] Preferably, the pressure inside the first cavity of the constant pressure diaphragm pressure tank is 1.5~15 MPa. At normal air pressure, it is 0.1 MPa, meaning the constant pressure diaphragm pressure tank occupies 15~150 times less volume compared to a normal pressure gas chamber.

[0028] In this embodiment, the pressure in the first cavity of the constant pressure diaphragm pressure vessel is 6 MPa, the working gas is carbon dioxide, and the second cavity is inside the first cavity, as shown below. Figure 1As shown, the outer cavity of the membrane is the first cavity, and the inner cavity is the second cavity. The working gas storage tank is a carbon dioxide storage tank. The balance pipe of the carbon dioxide storage tank is connected to the working gas pipeline between heat exchanger D and heat exchanger C. The pressure inside the carbon dioxide storage tank is the same as the pressure in the first and second cavities of the constant pressure diaphragm pressure tank, which is 6 MPa. The temperature of the liquid carbon dioxide inside the carbon dioxide storage tank is 22℃, which can effectively solve the risk of high-pressure alternating pressure operation of the constant pressure diaphragm pressure tank. Of course, the balance pipe of the carbon dioxide storage tank can also be connected to the working gas pipeline between heat exchanger D and the constant pressure diaphragm pressure tank, but this will have a certain impact on the airflow in the working gas pipeline.

[0029] The air compression energy release subsystem includes an air compression component, an air energy release component, and a heat exchange circulation mechanism mainly composed of a high-pressure heat storage tank A, a cold storage tank, and a heat storage tank C. The heat exchange circulation mechanism is also used to provide the heat energy released by the air compression component in the energy storage stage to the air energy release component in the energy release stage.

[0030] In this embodiment, the air compression assembly mainly consists of a primary air compressor, heat exchanger I (labeled heat exchanger 1 in the figure), a secondary air compressor, and heat exchanger II (labeled heat exchanger 2 in the figure) connected in sequence. The air compressor is used to absorb air from nature and compress it to 6 MPa. Of course, another compressor can be added to achieve compressed air of 15 MPa. High-pressure heat storage tank A is used to store the heat energy generated by air compression; the temperature of high-pressure heat storage tank A is around 200°C, and the temperature of the cold storage tank is around 40°C. The air energy release assembly consists of heat exchanger III (labeled heat exchanger 3 in the figure), a primary air turbine, heat exchanger IV (labeled heat exchanger 4 in the figure), and a secondary air turbine connected in sequence. The air turbine is used to expand the 6 MPa air to 0.1 MPa before discharging it into nature. High-pressure heat storage tank A provides the heat energy required for the expansion of compressed air, and heat storage tank C stores the cold energy generated by the expansion of air.

[0031] The operation process of the novel compressed air energy storage system of this utility model is as follows.

[0032] Energy Storage Phase: During off-peak electricity consumption at night, ambient air at normal temperature and pressure is compressed into 6 MPa high-pressure air by an air compressor unit and stored in an underground constant-pressure diaphragm pressure tank. Simultaneously, the heat generated during compression is stored in high-pressure heat storage tank A. As the high-pressure air in the constant-pressure diaphragm pressure tank increases, the 6 MPa high-pressure gaseous carbon dioxide in the second cavity of the air film is discharged from the pressure tank. It then undergoes efficient liquefaction through heat exchangers D and C, forming 6 MPa liquid carbon dioxide, which is stored in a carbon dioxide storage tank. This completes the process of nighttime air compression energy storage and high-pressure carbon dioxide liquefaction.

[0033] Energy Release Phase: During peak daytime electricity consumption, the 6MPa high-pressure gaseous air in the constant-pressure diaphragm pressure tank expands and generates electricity through an air turbine expander generator, releasing atmospheric-pressure gaseous air into the atmosphere. The heat energy required for the turbine expansion process comes from the high-pressure heat storage tank A, and the waste heat generated during expansion is stored in heat storage tank C. As the high-pressure air in the constant-pressure diaphragm pressure tank decreases, to maintain pressure balance, the 6MPa liquid carbon dioxide in the carbon dioxide storage tank is efficiently vaporized through a circulating pump and heat exchangers C and D to generate 6MPa gaseous carbon dioxide, which returns to the second cavity within the gas film of the constant-pressure diaphragm pressure tank. The heat energy required for vaporization comes from the high-pressure heat storage tanks A and C, and the collected cold energy is stored in a cold storage tank. This completes the daytime air energy release and power generation and carbon dioxide vaporization process.

[0034] During the carbon dioxide liquefaction process, the refrigeration unit provides sufficient cooling energy for the carbon dioxide liquefaction. Of course, other refrigeration compressor systems can also be used as replacements for the refrigeration unit.

[0035] In this embodiment, the temperature of high-pressure heat storage tank A is higher than that of heat storage tank C, and the temperature of heat storage tank C is higher than that of cold storage tank. The temperatures of high-pressure heat storage tank A, cold storage tank, and heat storage tank C will change depending on the operating conditions.

[0036] The above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A compressed air energy storage system, comprising a constant pressure diaphragm air tank, an air compression and energy release subsystem, and a constant pressure working gas gas-liquid conversion subsystem, the constant pressure diaphragm air tank is divided into a first cavity and a second cavity by a gas film, and the second cavity has the same pressure as the first cavity; the first cavity is in communication with the air compression and energy release subsystem, the air compression and energy release subsystem is used for storing compressed air in the first cavity in the energy storage stage, and is used for discharging the compressed air in the first cavity in the energy release stage; the second cavity is in communication with the constant pressure working gas gas-liquid conversion subsystem, characterized in that, The constant-pressure working medium gas and liquid conversion subsystem is mainly composed of a working medium gas storage tank, a heat exchanger C, a heat exchanger D, a cold source and a heat source. The constant-pressure working medium gas and liquid conversion subsystem is used for, in the energy storage stage, the working medium gas discharged from the second cavity to flow into the working medium gas storage tank after being liquefied by sequentially passing through the heat exchanger D and the heat exchanger C to absorb the cold energy provided by the cold source. The constant-pressure working medium gas and liquid conversion subsystem is used for, in the energy release stage, the liquid working medium gas discharged from the working medium gas storage tank to be vaporized by sequentially passing through the heat exchanger C and the heat exchanger D to absorb the heat energy provided by the heat source and then discharged into the second cavity.

2. A compressed air energy storage system according to claim 1, wherein, The cold source is a cold storage tank and a refrigeration unit, the cold storage tank is connected to the heat exchange pipelines of the heat exchanger C and the heat exchanger D through the refrigeration unit, and the cold storage tank and the refrigeration unit are used for sequentially providing the heat exchanger C and the heat exchanger D with cold energy.

3. A compressed air energy storage system according to claim 1, wherein, The heat source is a high-pressure heat storage tank A and a heat storage tank C, the high-pressure heat storage tank A is connected to the heat exchange pipelines of the heat exchanger C and the heat exchanger D, the high-pressure heat storage tank A is used for sequentially providing the heat exchanger D and the heat exchanger C with heat energy, and the heat storage tank C is connected to the heat exchange branch between the heat exchanger C and the heat exchanger D, and the heat storage tank C is used for providing the heat exchanger C with heat energy.

4. A compressed air energy storage system according to any one of claims 1 to 3, characterised in that, The pressure in the first cavity of the constant-pressure diaphragm gas pressure tank is 1.5-15 MPa.

5. A compressed air energy storage system according to claim 4, wherein, The pressure in the first cavity of the constant-pressure diaphragm gas pressure tank is 6 MPa, the working medium gas is carbon dioxide, and the second cavity is inside the first cavity.

6. A compressed air energy storage system according to any one of claims 1 to 3, wherein, The air compression and energy release subsystem comprises an air compression assembly, an air energy release assembly and a heat exchange circulation mechanism mainly composed of the high-pressure heat storage tank A, the cold storage tank and the heat storage tank C, and the heat exchange circulation mechanism is also used for providing the air energy release assembly in the energy release stage with heat energy released by the air compression assembly in the energy storage stage.

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