Novel compressed air energy storage system

Abstract

The invention discloses a novel compressed air energy storage system which comprises a constant-pressure diaphragm air pressure tank, an air compression energy release subsystem and a working medium gas gas-liquid conversion subsystem and has the advantages that two energy storage media are adopted, air serves as a main medium for compression expansion power generation, and working medium gas serves as a medium with stable pressure and does not participate in acting; alternation of air and 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, compared with traditional carbon dioxide energy storage, a large carbon dioxide air storage bin at the low-pressure end of traditional carbon dioxide energy storage is removed and replaced with inexhaustible air, the air is directly discharged into the atmosphere in the energy release stage, and the equipment cost and the medium cost of the low-pressure air storage end are greatly reduced.

Description

Technical Field

[0001] The invention relates to the technical field of energy storage systems, and in particular to a novel compressed air energy storage system. Background Art

[0002] Compressed air energy storage technology is a physical energy storage technology that uses compressed air to store energy. It has the advantages of large energy storage capacity, high safety, economy, environmental protection and mature technology. It plays an important role in the future energy system, especially in promoting the use of renewable energy and improving the stability of the power grid.

[0003] Carbon dioxide energy storage (CES) technology is a new physical energy storage technology based on compressed air energy storage (CAES) and Brayton power generation cycle. As a new technology, carbon dioxide energy storage uses a multi-stage compressor to convert atmospheric pressure gaseous carbon dioxide into high-pressure liquid carbon dioxide during the low electricity price period, and converts electrical energy into the form of carbon dioxide internal energy for storage; during the peak period of electricity consumption, the high-pressure liquid carbon dioxide is expanded and converted into atmospheric pressure gaseous carbon dioxide through a multi-stage expander to generate electricity, and finally realize the storage and release of electrical energy. However, this system has some disadvantages: ① Huge equipment investment. The whole system consists of low-pressure gas storage warehouse, high-pressure storage tank, compressor unit, turbine unit, heat exchange system and a large number of cold and heat storage tanks. In particular, the low-pressure gas storage warehouse uses atmospheric pressure to store carbon dioxide. Taking a 10MW carbon dioxide energy storage system as an example, its low-pressure gas storage warehouse will reach 1 million cubic meters, which will be a huge land cost in developed areas. The investment cost of these systems will be very huge, and the cost of technology promotion cannot be ignored and needs to be improved. Summary of the invention

[0004] A technical problem to be solved by the present application is to overcome the defects of the above-mentioned related technologies and provide a storage form that optimizes the traditional carbon dioxide energy storage and compressed air energy storage single medium low-pressure storage, replacing it with a new compressed air energy storage system that combines compressed air and compressed carbon dioxide with lightweight equipment and high energy storage efficiency.

[0005] The technical solution adopted by the present invention to solve the technical problem is: a new type of compressed air energy storage system, including a constant pressure diaphragm air pressure tank, an air compression energy release subsystem and a working gas gas-liquid conversion subsystem,

[0006] The constant pressure diaphragm air pressure tank is divided into a first cavity and a second cavity by an air film;

[0007] The first cavity is connected to an air compression energy release subsystem, and the air compression energy release subsystem is used to store 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;

[0008] The second cavity is connected to the working gas gas-liquid conversion subsystem, which is composed of a working gas liquid storage tank, a heat exchanger V, a low-temperature heat storage tank and a low-temperature cold storage tank; in the energy storage stage, the working gas discharged from the second cavity absorbs the cold energy of the low-temperature cold storage tank through the heat exchanger V and is liquefied before flowing into the working gas liquid storage tank; in the energy release stage, the working gas flowing out of the working gas liquid storage tank absorbs the heat energy of the low-temperature heat storage tank through the heat exchanger V and is gasified before being discharged into the second cavity;

[0009] The pressure in the first cavity is the same as that in the second cavity.

[0010] Compared with the related art, the present invention has the following advantages: the present invention adopts two energy storage media, air is used as the main medium for compression and expansion power generation, and the working gas is used as a pressure-stable medium and does not participate in work. The alternation of the two media, air and working gas, in the tank is completed through the contraction / expansion of the gas film, thereby achieving the pressure stabilization effect in the two stages of energy storage and energy release; air is used for compression and expansion power generation at the energy storage and energy release end. Compared with traditional carbon dioxide energy storage, the large carbon dioxide gas storage warehouse at the low-pressure end of traditional carbon dioxide energy storage is eliminated and replaced by inexhaustible air, which is also directly discharged into the atmosphere during the energy release stage, greatly reducing the equipment cost, land cost and medium cost of the low-pressure gas storage end.

[0011] Preferably, the pressure in the first cavity of the constant pressure diaphragm air tank is 3-15 MPa. The constant pressure diaphragm air tank reduces the occupied volume by 30-150 times compared with the air tank of normal pressure, which greatly reduces the land use cost.

[0012] As an improvement, the pressure in the first cavity of the constant pressure diaphragm air tank is 6Mpa, the working gas is carbon dioxide, and the second cavity is inside the first cavity. The physical property of carbon dioxide liquefies at 22°C at 6Mpa is utilized, and the volume change caused by the gasification and liquefaction of carbon dioxide is used to achieve the pressure balance of the air changes in the constant pressure diaphragm air tank, which solves the risk of high-pressure alternating pressure operation of the constant pressure diaphragm air tank, thereby realizing equipment miniaturization, lightweight equipment investment, high-quality energy storage and a more flexible and changeable new energy storage mode.

[0013] 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-temperature heat storage tank and a high-temperature cold storage tank, and the heat exchange circulation mechanism is 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.

[0014] Preferably, the air compression assembly is composed of a primary air compressor, a heat exchanger I, a secondary air compressor and a heat exchanger II connected in sequence.

[0015] Preferably, the air energy release component is composed of a heat exchanger III, a primary air turbine, a heat exchanger IV and a secondary air turbine connected in sequence.

[0016] Preferably, the working gas gas-liquid conversion subsystem is further provided with a refrigeration compressor unit, which is connected to the heat exchanger V, the low-temperature heat storage tank and the low-temperature cold storage tank. The refrigeration compressor unit provides sufficient cold energy for carbon dioxide liquefaction and sufficient heat energy for carbon dioxide gasification.

[0017] Preferably, the refrigeration compressor unit includes an internal circulation heat exchanger VII, a compressor, a heat exchanger VIII and a throttle valve, the heat exchanger VII is connected to the heat exchanger V, and the heat exchanger VIII is respectively connected to a low-temperature heat storage tank and a low-temperature cold storage tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a connection diagram of the novel compressed air energy storage system of the present application. DETAILED DESCRIPTION

[0019] First, those skilled in the art should understand that these implementations are only used to explain the technical principles of the embodiments of the present application, and are not intended to limit the protection scope of the embodiments of the present application. Those skilled in the art can make adjustments to them as needed to adapt to specific application scenarios.

[0020] The present invention is further described in detail below with reference to the accompanying drawings and specific embodiments.

[0021] The preferred embodiment is as follows Figure 1 A novel compressed air energy storage system shown in FIG. 1 includes a constant pressure diaphragm air pressure tank, an air compression energy release subsystem and a working fluid gas-to-liquid conversion subsystem.

[0022] The constant pressure diaphragm air pressure tank is divided into a first cavity and a second cavity by an air film;

[0023] The first cavity is connected to an air compression energy release subsystem, and the air compression energy release subsystem is used to store 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;

[0024] The second cavity is connected to the working gas gas-liquid conversion subsystem, which is composed of a working gas liquid storage tank, a heat exchanger V, a low-temperature heat storage tank and a low-temperature cold storage tank; in the energy storage stage, the working gas discharged from the second cavity absorbs the cold energy of the low-temperature cold storage tank through the heat exchanger V and is liquefied before flowing into the working gas liquid storage tank; in the energy release stage, the working gas flowing out of the working gas liquid storage tank absorbs the heat energy of the low-temperature heat storage tank through the heat exchanger V and is gasified before being discharged into the second cavity;

[0025] The pressure in the first cavity is the same as that in the second cavity and remains constant. The volume change of the compressed air in the energy storage stage and the energy release stage is balanced by the liquefaction and gasification of the working gas. The air film deforms flexibly as the storage volume of the air and working gas changes. The volume of the first cavity and the second cavity changes accordingly, causing the air film to shrink / expand, and keeping the air pressure in the constant pressure diaphragm air tank constant.

[0026] Preferably, the pressure in the first cavity of the constant pressure diaphragm air tank is 3-15 MPa, which is 0.1 MPa under normal air pressure, that is, the constant pressure diaphragm air tank reduces the occupied volume by 30-150 times compared with the normal pressure air tank.

[0027] In this embodiment, the pressure in the first cavity of the constant pressure diaphragm air tank is 6Mpa, the working gas is carbon dioxide, and the second cavity is inside the first cavity. The working gas storage tank is a carbon dioxide storage tank, and the pressure in the carbon dioxide storage tank is the same as the pressure in the first cavity and the second cavity of the constant pressure diaphragm air tank, which is 6Mpa. The temperature of the liquid carbon dioxide in the carbon dioxide storage tank is 22°C, which can effectively solve the risk of high-pressure alternating pressure operation of the constant pressure diaphragm air tank.

[0028] Among them, 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-temperature heat storage tank and a high-temperature cold storage tank. The heat exchange circulation mechanism is used to collect the heat energy released by the air compression component in the energy storage stage and provide it to the air energy release component in the energy release stage.

[0029] In this embodiment, the air compression assembly is mainly composed of a primary air compressor, a heat exchanger I (labeled as heat exchanger 1 in the figure), a secondary air compressor and a heat exchanger II (labeled as heat exchanger 2 in the figure) connected in sequence. The primary air compressor is used to absorb air from nature and compress it to 6Mpa. Of course, additional compressors can be added to achieve 15Mpa compressed air. The high-temperature heat storage tank is used to store the heat energy generated by air compression, and the temperature of the high-temperature heat storage tank is about 200°C.

[0030] In this embodiment, the air energy release assembly is composed of a heat exchanger III (labeled as heat exchanger 3 in the figure), a first-stage air turbine, a heat exchanger IV (labeled as heat exchanger 4 in the figure) and a second-stage air turbine connected in sequence. The first-stage air turbine is used to expand 6Mpa air to 0.1Mpa and then discharge it into nature. The high-temperature heat storage tank is used to provide the heat energy required for air expansion, and the high-temperature cold storage tank is used to store the cold energy generated by air expansion.

[0031] Preferably, the working gas gas-liquid conversion subsystem is further provided with a refrigeration compressor unit, which is connected to a heat exchanger V (heat exchanger 5 is indicated in the figure), a low-temperature heat storage tank and a low-temperature cold storage tank. Of course, the refrigeration compressor unit can also be replaced by other heat exchange and heat storage and refrigeration compressor systems. The temperature of the low-temperature heat storage tank is about 50°C.

[0032] The refrigeration compressor unit includes an internal circulation heat exchanger VII (labeled as heat exchanger 7 in the figure), a compressor, a heat exchanger VIII (labeled as heat exchanger 8 in the figure) and a throttle valve. The heat exchanger VII is connected to the heat exchanger V, and the heat exchanger VIII is respectively connected to the low-temperature heat storage tank and the low-temperature cold storage tank.

[0033] In addition, a heat exchanger VI (labeled as heat exchanger 6 in the figure) is provided between the low temperature heat storage tank and the heat exchanger VII, and the heat exchanger VI is connected to the high temperature heat storage tank and the high temperature cold storage tank. A pressure balance pipe is connected between the carbon dioxide storage tank and the second cavity, and a normally closed valve is provided on the pressure balance pipe.

[0034] The operation process of the novel compressed air energy storage system of the present invention is as follows.

[0035] Energy storage stage: During the low-peak period of electricity consumption at night, the air at normal temperature and pressure in the atmosphere is compressed by the air compressor unit to form 6Mpa high-pressure air, and stored in the constant-pressure diaphragm air tank underground. At the same time, the heat energy generated by the compression is stored in the high-temperature heat storage tank. When the high-pressure air in the constant-pressure diaphragm air tank increases, the 6Mpa high-pressure gaseous carbon dioxide in the air film is discharged out of the constant-pressure diaphragm air tank, liquefied through the heat exchanger 5, forming 6Mpa liquid carbon dioxide, and stored in the carbon dioxide liquid storage tank. Finally, the process of nighttime air energy storage and carbon dioxide liquefaction is completed.

[0036] Energy release stage: During the peak period of electricity consumption during the day, the 6Mpa high-pressure gaseous air in the constant-pressure diaphragm air tank is expanded and generates electricity through the air turbine expansion generator set, forming normal-pressure gaseous air and discharging it into the atmosphere. The heat energy required in the turbine expansion process comes from the high-temperature heat storage tank, and the cold energy generated by the expansion is stored in the high-temperature cold storage tank. When the high-pressure air in the constant-pressure diaphragm air tank becomes less and less, in order to maintain the pressure balance in the constant-pressure diaphragm air tank, the 6Mpa liquid carbon dioxide in the carbon dioxide storage tank is gasified through the circulation pump and the heat exchanger 5 to generate 6Mpa gaseous carbon dioxide and return to the air film of the constant-pressure diaphragm air tank. The heat energy required for gasification comes from the low-temperature heat storage tank and the heat exchanger 6, and the collected cold energy is stored in the low-temperature heat storage tank. Finally, the process of air energy release and power generation and carbon dioxide gasification during the day is completed.

[0037] During the carbon dioxide energy storage liquefaction and gasification process, the refrigeration compressor unit provides sufficient cold energy for carbon dioxide liquefaction and sufficient heat energy for carbon dioxide gasification.

[0038] In this embodiment, the temperature of the high-temperature heat storage tank is higher than that of the low-temperature heat storage tank, the temperature of the high-temperature cold storage tank is higher than that of the low-temperature cold storage tank, and the temperatures of the high-temperature heat storage tank, the high-temperature cold storage tank, the low-temperature heat storage tank and the low-temperature cold storage tank will change according to different working conditions.

[0039] The above is only a specific implementation of the present application, but the protection scope of the present application is not limited thereto. Any changes or substitutions that can be easily thought of by a person skilled in the art within the technical scope disclosed in the present application should be included in the protection scope of the present application. Therefore, the protection scope of the present application shall be based on the protection scope of the claims.

Claims

1. A new type of compressed air energy storage system, characterized in that: It includes a constant pressure diaphragm air pressure tank, an air compression energy release subsystem and a working gas gas-liquid conversion subsystem. The constant pressure diaphragm air pressure tank is divided into a first cavity and a second cavity by an air film; The first cavity is connected to an air compression energy release subsystem, and the air compression energy release subsystem is used to store 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 working gas gas-liquid conversion subsystem, which is composed of a working gas liquid storage tank, a heat exchanger V, a low-temperature heat storage tank and a low-temperature cold storage tank; in the energy storage stage, the working gas discharged from the second cavity absorbs the cold energy of the low-temperature cold storage tank through the heat exchanger V and is liquefied before flowing into the working gas liquid storage tank; in the energy release stage, the working gas flowing out of the working gas liquid storage tank absorbs the heat energy of the low-temperature heat storage tank through the heat exchanger V and is gasified before being discharged into the second cavity; The pressure in the first cavity is the same as that in the second cavity.

2. A novel compressed air energy storage system according to claim 1, characterized in that: The pressure in the first cavity of the constant pressure diaphragm air pressure tank is 3-15 MPa.

3. A novel compressed air energy storage system according to claim 2, characterized in that: The pressure in the first cavity of the constant pressure diaphragm air pressure tank is 6 MPa, the working gas is carbon dioxide, and the second cavity is inside the first cavity.

4. A novel compressed air energy storage system according to claim 3, characterized in that: 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-temperature heat storage tank and a high-temperature cold storage tank. The heat exchange circulation mechanism is 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.

5. A novel compressed air energy storage system according to claim 4, characterized in that: The air compression assembly is composed of a primary air compressor, a heat exchanger I, a secondary air compressor and a heat exchanger II which are connected in sequence.

6. A novel compressed air energy storage system according to claim 4, characterized in that: The air energy release component is composed of a heat exchanger III, a primary air turbine, a heat exchanger IV and a secondary air turbine which are connected in sequence.

7. A novel compressed air energy storage system according to any one of claims 1 to 6, characterized in that: The working gas gas-liquid conversion subsystem is also provided with a refrigeration compressor unit, and the refrigeration compressor unit is connected to the heat exchanger V, the low-temperature heat storage tank and the low-temperature cold storage tank.

8. A novel compressed air energy storage system according to claim 7, characterized in that: The refrigeration compressor unit includes an internal circulation heat exchanger VII, a compressor, a heat exchanger VIII and a throttle valve. The heat exchanger VII is connected to the heat exchanger V, and the heat exchanger VIII is connected to a low-temperature heat storage tank and a low-temperature cold storage tank respectively.

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