Subcritical water compression gas energy storage system and control method thereof

Abstract

The present application relates to compressed gas energy storage technology field, specifically to a kind of subcritical water compressed gas energy storage system and control method thereof.Energy storage system includes: gas storage device, energy storage pipeline, energy release pipeline, compression component, expansion component, cold storage tank, heat storage tank, supercooling pipeline, first heat exchanger, first pressure regulating component etc., first pressure regulating component is directly or indirectly communicated with the cold storage tank.The subcritical water compressed gas energy storage system provided by the present application sets first pressure regulating component, so that the water pressure of cold subcritical water in supercooling pipeline can be adjusted in real time, so that cold subcritical water can be in the best pressure state at any temperature, improve the heat exchange efficiency of compressed gas energy storage system using subcritical water as heat exchange medium.At the same time, through the control method of system, the pressure of subcritical water in heat exchange process of heat storage system can be automatically selected according to the temperature of compressed air at the outlet of compression component, realize the efficient and stable operation of compressed air energy storage power station heat storage system.

Description

Technical Field

[0001] This invention relates to the field of compressed gas energy storage technology, specifically to a subcritical water compressed gas energy storage system and its control method. Background Technology

[0002] For large-scale energy storage systems, traditional physical energy storage methods such as pumped hydro storage and compressed air energy storage are currently the most widely used energy storage technologies. However, pumped hydro storage and compressed air energy storage have high requirements for geographical site selection, which limits their widespread application. Therefore, compressed air energy storage technology, with its advantages of large energy storage capacity, long energy storage cycle, low investment, and environmental friendliness, is considered to be the large-scale energy storage technology with the broadest development prospects.

[0003] The heat exchange system is one of the core components of compressed gas energy storage systems. Traditional compressed air energy storage power stations primarily use subcritical water as the heat exchange medium. Subcritical water refers to water heated to above its boiling point but below its critical point, with the system pressure controlled to maintain the water in a liquid state. However, the heat exchange efficiency of subcritical water varies greatly under different temperature and pressure conditions. Therefore, how to achieve higher heat exchange efficiency in compressed gas energy storage systems using subcritical water as the heat exchange medium is a pressing issue that needs to be addressed. Summary of the Invention

[0004] Therefore, the technical problem to be solved by the present invention is to overcome the defect in the existing compressed gas energy storage system that uses subcritical water as the heat exchange medium, where the heat exchange efficiency of subcritical water varies greatly under different temperature and pressure conditions.

[0005] Therefore, the present invention provides a subcritical water compressed gas energy storage system, comprising:

[0006] Gas storage device, suitable for storing energy gases;

[0007] The energy storage pipeline and the energy release pipeline are respectively connected to the gas storage device;

[0008] A compression assembly and an expansion assembly are provided, wherein the compression assembly is disposed on the energy storage pipeline and is adapted to compress the energy storage gas to store energy, and the expansion assembly is disposed on the energy release pipeline and is adapted to expand the energy storage gas to release energy;

[0009] Cold storage tanks and hot storage tanks are suitable for storing cold subcritical water and hot subcritical water, respectively.

[0010] A subcooling pipeline connects the cold storage tank and the heat storage tank, and the subcooling pipeline is adapted to guide the subcritical cold water.

[0011] A first heat exchanger is heat-exchangeably disposed between the energy storage pipeline and the subcooling pipeline;

[0012] The first pressure regulating component is directly or indirectly connected to the cold storage tank and is suitable for regulating the water pressure of the cold subcritical water.

[0013] Optionally, it also includes:

[0014] A superheated pipeline connects the cold storage tank and the hot storage tank, and the superheated pipeline is adapted to guide the subcritical thermal water.

[0015] A second heat exchanger is heat-exchangeably disposed between the energy-releasing pipeline and the superheating pipeline;

[0016] The second pressure regulating component is directly or indirectly connected to the thermal storage tank and is suitable for regulating the water pressure of the thermal subcritical water.

[0017] Optionally, the first pressure regulating component is disposed on the subcooling pipeline, and the first pressure regulating component is adapted to regulate the water pressure of the subcritical cold water discharged from the cold storage tank.

[0018] Optionally, the second pressure regulating component is connected to the thermal storage tank, and the second pressure regulating component is adapted to regulate the water pressure of the cold subcritical water stored in the cold storage tank.

[0019] Optionally, the system further includes a controller, which is communicatively connected to the first voltage regulating component and the second voltage regulating component, respectively, and the controller is adapted to control the start and stop of the first voltage regulating component or the second voltage regulating component.

[0020] Optionally, a buffer tank suitable for storing subcritical water is provided on the superheated pipeline. The buffer tank is located above the altitude of the cold storage tank. A water turbine is provided at the outlet of the buffer tank, and the water turbine is powered by a first generator.

[0021] Optionally, the first pressure regulating component is configured as a cold water pump.

[0022] Optionally, the second pressure regulating component is configured as a nitrogen regulating tank, the nitrogen regulating tank including a receiving cavity adapted to contain nitrogen and a piston adapted to compress the receiving cavity, the receiving cavity being in communication with the heat storage tank.

[0023] Optionally, it further includes an atmospheric pressure nitrogen tank, which is connected to the cold storage tank, and the atmospheric pressure nitrogen tank is adapted to introduce atmospheric pressure nitrogen into the cold storage tank; and / or

[0024] The compression assembly includes a compressor and an electric motor connected to the compressor, and the expansion assembly includes an expander and a second generator connected to the expander.

[0025] The present invention also provides a control method, which is applied to the subcritical water compressed gas energy storage system described in any of the above embodiments, comprising:

[0026] S1: Lower the water level in the heat storage tank to the lowest level and adjust the second pressure regulating component to make the internal pressure of the heat storage tank 2.0 MPa;

[0027] S2: Start the compression assembly, obtain the gas temperature T1 at the outlet of the compression assembly, obtain the water temperature T2 of the cold storage tank, and calculate the internal target pressure P1 of the heat storage tank according to the following formula;

[0028]

[0029] S3: Adjust the second pressure regulating component to make the internal pressure of the heat storage tank reach P1;

[0030] S4: Adjust the first pressure regulating component to make the water pressure in the subcooled pipeline reach P1, thus completing the initial adjustment of the subcritical water pressure.

[0031] S5: When the gas temperature T1 at the outlet of the compression component and the water temperature T2 in the cold storage tank change, repeat S2-S4 to adjust the subcritical water pressure in real time.

[0032] The technical solution of this invention has the following advantages:

[0033] 1. This invention provides a subcritical water compressed gas energy storage system, comprising: a gas storage device suitable for storing energy-storing gas; an energy storage pipeline and an energy release pipeline respectively connected to the gas storage device; a compression component and an expansion component, wherein the compression component is disposed on the energy storage pipeline and is suitable for compressing the energy-storing gas to store energy, and the expansion component is disposed on the energy release pipeline and is suitable for expanding the energy-storing gas to release energy; a cold storage tank and a hot storage tank suitable for storing cold subcritical water and hot subcritical water respectively; a subcooling pipeline connecting the cold storage tank and the hot storage tank, wherein the subcooling pipeline is suitable for guiding the cold subcritical water; a first heat exchanger heat-exchangeably disposed between the energy storage pipeline and the subcooling pipeline; and a first pressure regulating component directly or indirectly connected to the cold storage tank and suitable for regulating the water pressure of the cold subcritical water.

[0034] This invention provides a subcritical water compressed gas energy storage system. By incorporating a first pressure regulating component in the subcritical water circulation system used for heat exchange, the water pressure of the cold subcritical water in the subcooled pipeline can be adjusted in real time. This ensures that the cold subcritical water in the subcooled pipeline is at its optimal pressure state at any temperature, thereby improving the heat exchange efficiency of the compressed gas energy storage system using subcritical water as the heat exchange medium. This overcomes the deficiency in existing compressed gas energy storage systems using subcritical water as the heat exchange medium, where the heat exchange efficiency of subcritical water varies greatly under different temperature and pressure conditions.

[0035] 2. The present invention provides a subcritical water compressed gas energy storage system, further comprising: a superheated pipeline connecting the cold storage tank and the heat storage tank, the superheated pipeline being adapted to guide the thermal subcritical water; a second heat exchanger being heat-exchangeably disposed between the energy release pipeline and the superheated pipeline; and a second pressure regulating component being directly or indirectly connected to the heat storage tank and adapted to regulate the water pressure of the thermal subcritical water.

[0036] Subcritical water flows through the entire superheated pipeline, keeping the entire pipeline at a high temperature. The subcooled and superheated pipelines are connected between the cold and hot storage tanks, respectively, enabling the circulation of subcritical water between them. A second heat exchanger exchanges heat between the subcritical water in the superheated pipeline and the low-temperature gas in the energy release pipeline, causing the gas to expand and release energy. This released energy is then further converted into usable energy by a conversion device. A second pressure regulating component is directly or indirectly connected to the hot storage tank to regulate the water pressure of the subcritical water in the tank, or to regulate the water pressure of the subcritical water in the superheated pipeline at the tank's outlet. This ensures that the subcritical water in the superheated pipeline is at its optimal pressure at any temperature, further improving the heat exchange efficiency of the compressed gas energy storage system using subcritical water as the heat exchange medium.

[0037] 3. The present invention provides a subcritical water compressed gas energy storage system, wherein the first pressure regulating component is disposed on the subcooled pipeline, and the first pressure regulating component is adapted to regulate the water pressure of the cold subcritical water discharged from the cold storage tank.

[0038] The first pressure regulating component is installed on the subcooling pipeline. This means that the pressure of the subcritical cold water in the subcooling pipeline of the cold storage tank outlet is regulated by the first pressure regulating component. There is no need to directly pressurize the subcritical cold water in the cold storage tank. The cold storage tank is only needed to store subcritical cold water at normal pressure. Therefore, there is no need to reinforce the cold storage tank with thick walls. Compared with the cold storage tank that requires thick walls to be used to directly pressurize the subcritical cold water in the cold storage tank, the construction cost of the cold storage tank is reduced, and the cost of the entire heat exchange system is reduced. Attached Figure Description

[0039] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0040] Figure 1 This is a schematic diagram of a subcritical water compressed gas energy storage system provided by the present invention.

[0041] Explanation of reference numerals in the attached figures:

[0042] 1. Gas storage device; 2. Compression assembly; 201. Compressor; 202. Electric motor; 3. Expansion assembly; 301. Expander; 302. Second generator; 4. Cold storage tank; 5. Heat storage tank; 6. First heat exchanger; 7. First pressure regulating assembly; 8. Second heat exchanger; 9. Second pressure regulating assembly; 10. Controller; 11. Buffer tank; 1101. Water turbine; 1102. First generator; 1103. Gearbox; 12. Cold water pump; 13. Nitrogen regulating tank; 1301. High-pressure nitrogen replenishment valve; 1302. High-pressure nitrogen relief valve; 14. Atmospheric pressure nitrogen tank; 1401. Atmospheric pressure nitrogen replenishment valve; 15. Hot water pump; 16. Check valve;

[0043] L1, energy storage pipeline; L2, energy release pipeline; L3, subcooling pipeline; L4, superheating pipeline. Detailed Implementation

[0044] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0045] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0046] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0047] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0048] For large-scale energy storage systems, traditional physical energy storage methods such as pumped hydro storage and compressed air energy storage are currently the most widely used energy storage technologies. However, pumped hydro storage and compressed air energy storage have high requirements for geographical site selection, which limits their widespread application. Therefore, compressed air energy storage technology, with its advantages of large energy storage capacity, long energy storage cycle, low investment, and environmental friendliness, is considered to be the large-scale energy storage technology with the broadest development prospects.

[0049] The heat exchange system is one of the core components of compressed gas energy storage systems. Traditional compressed air energy storage power stations primarily use subcritical water as the heat exchange medium. Subcritical water refers to water heated to above its boiling point but below its critical point, with the system pressure controlled to maintain the water in a liquid state. However, the heat exchange efficiency of subcritical water varies greatly under different temperature and pressure conditions. Therefore, how to achieve higher heat exchange efficiency in compressed gas energy storage systems using subcritical water as the heat exchange medium is a pressing issue that needs to be addressed.

[0050] Therefore, the technical problem to be solved by the present invention is to overcome the defect in the existing compressed gas energy storage system that uses subcritical water as the heat exchange medium, where the heat exchange efficiency of subcritical water varies greatly under different temperature and pressure conditions.

[0051] Example 1

[0052] This embodiment provides a subcritical water compressed gas energy storage system, including: a gas storage device 1, an energy storage pipeline L1, an energy release pipeline L2, a compression assembly 2, an expansion assembly 3, a cold storage tank 4, a heat storage tank 5, a subcooling pipeline L3, a first heat exchanger 6, a first pressure regulating assembly 7, etc.

[0053] The gas storage device 1 is suitable for storing energy-storing gas; the energy storage pipeline L1 and the energy release pipeline L2 are respectively connected to the gas storage device 1; the compression component 2 is installed on the energy storage pipeline L1 and is suitable for compressing the energy storage gas to store energy; the expansion component 3 is installed on the energy release pipeline L2 and is suitable for expanding the energy storage gas to release energy.

[0054] Specifically, such as Figure 1 As shown, the gas storage device 1 stores energy-storing gas that flows through the energy storage pipeline L1 and the energy release pipeline L2. Under the combined action of the compression component 2 and the expansion component 3, the gas undergoes compression and expansion to release energy. The compression component 2, located on the energy storage pipeline L1, is suitable for compressing the gas and generating a higher temperature for temporary storage in the gas storage device 1, thus achieving gas energy storage. The expansion component 3, located on the energy release pipeline L2, is suitable for expanding the gas and generating a lower temperature. During this conversion process, the gas releases energy, which is then further converted into usable energy using a conversion device, thus completing the gas energy storage and release operation.

[0055] Furthermore, another gas storage device can be connected to the gas inlet and gas outlet respectively to form a complete cycle energy storage system. Of course, the gas storage device 1 itself can also form two chambers, one chamber is suitable for introducing the compressed gas after compression by the compression component 2, and the other chamber is suitable for introducing the expanded gas after expansion by the expansion component 3, thus forming a complete cycle energy storage system.

[0056] Furthermore, the gas can be air, or carbon dioxide, nitrogen, etc.

[0057] Furthermore, the first heat exchanger 6 is configured as a cooler.

[0058] The cold storage tank 4 and the hot storage tank 5 are suitable for storing cold subcritical water and hot subcritical water respectively; the subcooling pipeline L3 connects the cold storage tank 4 and the hot storage tank 5, and the subcooling pipeline L3 is suitable for guiding the cold subcritical water; the first heat exchanger 6 is heat-exchangeably arranged between the energy storage pipeline L1 and the subcooling pipeline L3.

[0059] Specifically, such as Figure 1 As shown, cold subcritical water flows through the entire subcooled pipeline L3, keeping the entire subcooled pipeline L3 at a low temperature. The first heat exchanger 6 compresses the gas in the energy storage pipeline L1, releasing a large amount of heat, which exchanges heat with the cold subcritical water in the subcooled pipeline L3. After the heat exchange is completed, the cold subcritical water is heated and converted into hot subcritical water, which is stored in the heat storage tank 5. When the gas expands and releases energy, the hot subcritical water can be used as a heating unit through other pipes and heat exchange elements to heat the low-temperature gas after the energy is released. After the hot subcritical water cools down, it becomes cold subcritical water and continues to be stored in the cold storage tank 4, thus realizing the circulation and utilization of subcritical water.

[0060] The first pressure regulating component 7 is directly or indirectly connected to the cold storage tank 4 and is suitable for regulating the water pressure of the cold subcritical water.

[0061] Specifically, the first pressure regulating component 7 is directly or indirectly connected to the cold storage tank 4 and is used to regulate the water pressure of the cold subcritical water in the cold storage tank 4, or to regulate the water pressure of the cold subcritical water in the subcooling pipeline L3 of the outlet pipe of the cold storage tank 4, so that the cold subcritical water in the subcooling pipeline L3 can be in the optimal pressure state at any temperature, thereby improving the heat exchange efficiency of the compressed gas energy storage system using subcritical water as the heat exchange medium.

[0062] Furthermore, when the first pressure regulating component 7 is directly connected to the cold storage tank 4, the first pressure regulating component 7 directly regulates the water pressure of the cold subcritical water in the cold storage tank 4; when the first pressure regulating component 7 is indirectly connected to the cold storage tank 4, the first pressure regulating component 7 regulates the water pressure of the cold subcritical water in the subcooling pipeline L3 of the outlet pipeline of the cold storage tank 4.

[0063] Furthermore, the first pressure regulating component 7 can be configured as a flow pump, a gas replenishment tank, etc.

[0064] This embodiment provides a subcritical water compressed gas energy storage system. By incorporating a first pressure regulating component 7 in the subcritical water circulation system used for heat exchange, the water pressure of the cold subcritical water in the subcooled pipeline L3 can be adjusted in real time. This ensures that the cold subcritical water in the subcooled pipeline L3 is at its optimal pressure state at any temperature, thereby improving the heat exchange efficiency of the compressed gas energy storage system using subcritical water as the heat exchange medium. This overcomes the deficiency in existing compressed gas energy storage systems using subcritical water as the heat exchange medium, where the heat exchange efficiency of subcritical water varies greatly under different temperature and pressure conditions.

[0065] Based on the above embodiments, as a further limiting embodiment, such as... Figure 1 As shown, the subcritical water compressed gas energy storage system also includes: superheated pipeline L4, second heat exchanger 8, second pressure regulating component 9, etc.

[0066] The superheated pipeline L4 connects the cold storage tank 4 and the heat storage tank 5. The superheated pipeline L4 is suitable for guiding subcritical thermal water. The second heat exchanger 8 is heat-exchangeably arranged between the energy release pipeline L2 and the superheated pipeline L4.

[0067] Specifically, subcritical water flows through the entire superheated pipeline L4, keeping the entire superheated pipeline L4 at a high temperature. The subcooled pipeline L3 and the superheated pipeline L4 are connected between the cold storage tank 4 and the heat storage tank 5, respectively, enabling the subcritical water to circulate and be utilized between the two tanks. A second heat exchanger 8 is used to exchange heat between the subcritical water in the superheated pipeline L4 and the low-temperature gas in the energy release pipeline L2, causing the gas to expand and release energy. A conversion device further converts the released energy into usable energy.

[0068] The second pressure regulating component 9 is directly or indirectly connected to the thermal storage tank 5 and is suitable for regulating the water pressure of the thermal subcritical water.

[0069] Specifically, the second pressure regulating component 9 is directly or indirectly connected to the heat storage tank 5 and is used to regulate the water pressure of the hot subcritical water in the heat storage tank 5, or to regulate the water pressure of the hot subcritical water in the superheated pipeline L4 of the outlet pipe of the heat storage tank 5. This also ensures that the cold subcritical water in the superheated pipeline L4 is in the optimal pressure state at any temperature, further improving the heat exchange efficiency of the compressed gas energy storage system using subcritical water as the heat exchange medium.

[0070] Furthermore, when the second pressure regulating component 9 is directly connected to the thermal storage tank 5, the second pressure regulating component 9 directly regulates the water pressure of the cold subcritical water in the thermal storage tank 5; when the second pressure regulating component 9 is indirectly connected to the thermal storage tank 5, the second pressure regulating component 9 regulates the water pressure of the cold subcritical water in the superheated pipeline L4 of the outlet pipe of the thermal storage tank 5.

[0071] Furthermore, similarly, the first pressure regulating component 7 can be configured as a flow pump, a gas replenishment tank, etc.

[0072] Furthermore, the second heat exchanger 8 is configured as a heater.

[0073] Furthermore, a hot water pump 15 is installed in the superheated pipeline L4 to guide the subcritical heat exchange water.

[0074] Based on the above embodiments, as a further limiting embodiment, such as... Figure 1 As shown, the first pressure regulating component 7 is installed on the subcooling pipeline L3, and the first pressure regulating component 7 is adapted to regulate the water pressure of the subcritical cold water discharged from the cold storage tank 4.

[0075] Specifically, to prevent liquid water from vaporizing at high temperatures, a high-pressure state is required within the system, resulting in a very high system design pressure. This necessitates thick-walled components for the system's metal pipes and pressure vessels, leading to a high overall system cost. Therefore, reducing system cost is crucial. In this embodiment, the first pressure regulating component 7 is installed on the subcooling pipe L3. This component regulates the water pressure of the subcritical cold water in the subcooling pipe L3, the outlet pipe of the cold storage tank 4, eliminating the need to directly pressurize the subcritical cold water in the cold storage tank 4. The cold storage tank 4 is sufficient for storing subcritical cold water at atmospheric pressure, thus eliminating the need for thick-walled reinforcement. Compared to the need for a thick-walled cold storage tank 4 for directly pressurizing the subcritical cold water, this reduces the construction cost of the cold storage tank 4 and lowers the overall cost of the heat exchange system.

[0076] Furthermore, a check valve 16 is installed in the subcooling pipe L3 of the outlet pipe of the cold storage tank 4 to prevent the pressurized subcritical cold water in the subcooling pipe L3 from flowing back into the cold storage tank 4.

[0077] Based on the above embodiments, as a further limiting embodiment, such as... Figure 1 As shown, the second pressure regulating component 9 is connected to the thermal storage tank 5, and the second pressure regulating component 9 is suitable for regulating the water pressure of the cold subcritical water stored in the cold storage tank 4.

[0078] Specifically, since the thermal storage tank 5 itself needs to store high-pressure cold subcritical water, the second pressure regulating component 9 is directly connected to the thermal storage tank 5, and the second pressure regulating component 9 can directly regulate the water pressure of the cold subcritical water in the thermal storage tank 5.

[0079] Furthermore, cold storage tank 4 and heat storage tank 5 were designed for high-pressure subcritical water and atmospheric-pressure subcritical water, respectively, reducing the cost of the heat exchange system by about 40%.

[0080] Based on the above embodiments, as a further limiting embodiment, such as... Figure 1 As shown, the subcritical water compressed gas energy storage system also includes a controller 10.

[0081] The controller 10 is communicatively connected to the first voltage regulating component 7 and the second voltage regulating component 9 respectively, and the controller 10 is adapted to control the start and stop of the first voltage regulating component 7 or the second voltage regulating component 9.

[0082] Specifically, the controller 10 controls the start and stop of the first pressure regulating component 7 or the second pressure regulating component 9, and adjusts the subcritical water system pressure in real time through model calculation, so that the subcritical water compressed gas energy storage system can ensure high heat exchange efficiency under any operating conditions, and has the advantages of simple system, convenient operation and stable operation.

[0083] Based on the above embodiments, as a further limiting embodiment, such as... Figure 1 As shown, a buffer tank 11 suitable for storing subcritical water is installed on the superheated pipeline L4. The buffer tank 11 is located above the altitude of the cold storage tank 4. A water turbine 1101 is installed at the outlet of the buffer tank 11. The water turbine 1101 is powered by the first generator 1102.

[0084] Specifically, the buffer tank 11 is set above the altitude of the cold storage tank 4. The subcritical water in the superheated pipeline L4 flows under its own high pressure through the buffer tank 11 at the higher altitude, and then flows from the buffer tank 11 into the cold storage tank 4. The pressure energy and potential energy of the subcritical water are recovered by utilizing the height difference between the buffer tank 11 and the cold storage tank 4. The water turbine 1101 converts the water turbine 1101 into mechanical energy. The gearbox 1103 connects the water turbine 1101 to the first generator 1102. The first generator 1102 further converts the mechanical energy into electrical energy, thereby recovering energy for power generation and improving system efficiency.

[0085] Furthermore, the buffer tank 11 is positioned 20m-50m above the altitude of the cold storage tank 4.

[0086] Based on the above embodiments, as a preferred embodiment, such as Figure 1 As shown, the first pressure regulating component 7 is configured as a cold water pump 12.

[0087] Specifically, the cold water pump 12 is installed in the subcooling pipe L3. While guiding the heat exchange subcritical water, it can also regulate the water pressure in the subcooling pipe L3, so that the cold subcritical water in the subcooling pipe L3 can be in the optimal pressure state at any temperature.

[0088] Furthermore, the controller 10 adjusts the subcritical water system pressure in real time according to the model calculation, controls the regulating device on the cold water pump 12, and regulates the cold water pump 12.

[0089] Based on the above embodiments, as a further limiting embodiment, such as... Figure 1 As shown, the second pressure regulating component 9 is configured as a nitrogen regulating tank 13, which includes a receiving cavity suitable for containing nitrogen and a piston suitable for compressing the receiving cavity. The receiving cavity is connected to the heat storage tank 5.

[0090] Specifically, the nitrogen regulating tank 13 is directly connected to the heat storage tank 5. By pushing the piston to compress the volume of the receiving cavity, high-pressure nitrogen is injected into the heat storage tank 5 to regulate the water pressure in the heat storage tank 5, so that the subcritical water in the superheated pipeline L4 can be in the optimal pressure state at any temperature.

[0091] Furthermore, the controller 10 adjusts the subcritical water system pressure in real time according to the model calculation, controls the movement of the connecting rod of the piston on the cold water pump 12, and regulates the nitrogen regulating tank 13.

[0092] Furthermore, injecting nitrogen into the thermal storage tank 5 facilitates nitrogen sealing of the subcritical water surface in the thermal storage tank 5, preventing the subcritical water from contacting the air and dissolving and absorbing oxygen from the air.

[0093] Furthermore, such as Figure 1 As shown, by providing a pipe and a high-pressure nitrogen replenishment valve 1301 that are connected to the containment cavity, it is convenient to replenish nitrogen to the nitrogen regulating tank 13.

[0094] Furthermore, such as Figure 1 As shown, by setting up a pipe connected to the heat storage tank 5 and a high-pressure nitrogen relief valve 1302, it is convenient to release nitrogen from the nitrogen regulating tank 13 to achieve the pressure relief operation.

[0095] Based on the above embodiments, as a further limiting embodiment, such as... Figure 1As shown, the subcritical water compressed gas energy storage system also includes an atmospheric pressure nitrogen tank 14, which is connected to the cold storage tank 4. The atmospheric pressure nitrogen tank 14 is adapted to introduce atmospheric pressure nitrogen into the cold storage tank 4.

[0096] Specifically, nitrogen is injected into the cold storage tank 4 through the atmospheric pressure nitrogen tank 14 to facilitate nitrogen sealing of the subcritical water in the cold storage tank 4, thereby preventing the subcritical water from contacting the air and dissolving and absorbing oxygen from the air.

[0097] Furthermore, such as Figure 1 As shown, by setting up a pipe connected to the cold storage tank 4 and an atmospheric pressure nitrogen replenishment valve 1401, it is convenient to replenish nitrogen to the cold storage tank 4.

[0098] Based on the above embodiments, as a further limiting embodiment, such as... Figure 1 As shown, the compression assembly 2 includes a compressor 201 and an electric motor 202 that is powered by the compressor 201, and the expansion assembly 3 includes an expander 301 and a second generator 302 that is powered by the expander 301.

[0099] Specifically, the electric motor 202 supplies power to the compressor 201, enabling the compressor 201 to compress the gas and generate a higher temperature for temporary storage in the gas storage device 1, thereby realizing gas energy storage and ensuring the normal operation of gas compression energy storage; the expander 301 rotates under the pressure of the gas to generate mechanical energy, and the second generator 302 connected to its power source converts this mechanical energy into electrical energy, thereby completing the conversion of gas expansion energy release into subsequent energy utilization.

[0100] Example 2

[0101] This embodiment provides a control method applied to a subcritical water compressed gas energy storage system provided in Embodiment 1, comprising the following steps:

[0102] S1: Lower the water level in the thermal storage tank 5 to the minimum level and adjust the second pressure regulating component 9 to make the internal pressure of the thermal storage tank 5 2.0 MPa;

[0103] S2: Start the compression assembly 2, obtain the gas temperature T1 at the outlet of the compression assembly 2, obtain the water temperature T2 in the cold storage tank 4, and calculate the internal target pressure P1 of the heat storage tank 5 according to the following formula;

[0104]

[0105] S3: Adjust the second pressure regulating component 9 to make the internal pressure of the heat storage tank 5 reach P1;

[0106] S4: Adjust the first pressure regulating component 7 to make the water pressure in the subcooling pipe L3 reach P1, thus completing the initial adjustment of the subcritical water pressure.

[0107] S5: When the gas temperature T1 at the outlet of the compression component 2 and the water temperature T2 in the cold storage tank 4 change, repeat S2-S4 to adjust the subcritical water pressure in real time.

[0108] This embodiment provides a control method for a subcritical water compressed gas energy storage system. By regulating the first pressure regulating component 7 and the second pressure regulating component 9, the cold subcritical water in the subcooled pipeline L3 and the cold subcritical water in the superheated pipeline L4 can be maintained at optimal pressure at any temperature, thereby improving the heat exchange efficiency of the compressed gas energy storage system using subcritical water as the heat exchange medium. This overcomes the deficiency in existing compressed gas energy storage systems using subcritical water as the heat exchange medium, where the heat exchange efficiency of subcritical water varies greatly under different temperature and pressure conditions.

[0109] Furthermore, a subcritical water compressed gas energy storage system, through the above-mentioned control method, can automatically select the pressure of subcritical water during the heat exchange process of the heat storage system according to the temperature of the compressed air at the outlet of the compression component 2, thereby achieving efficient and stable operation of the compressed air energy storage power station's heat storage system.

[0110] Furthermore, the compression component 2 is configured as a compressor.

[0111] Obviously, the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A subcritical water gas compression energy storage system, characterized by, include: Gas storage device (1), suitable for storing energy storage gas; The energy storage pipeline (L1) and the energy release pipeline (L2) are respectively connected to the gas storage device (1); Compression assembly (2) and expansion assembly (3), wherein the compression assembly (2) is disposed on the energy storage pipeline (L1) and is adapted to compress the energy storage gas to store energy, and the expansion assembly (3) is disposed on the energy release pipeline (L2) and is adapted to expand the energy storage gas to release energy; The cold storage tank (4) and the hot storage tank (5) are suitable for storing cold subcritical water and hot subcritical water respectively; The subcooling pipeline (L3) connects the cold storage tank (4) and the heat storage tank (5), and the subcooling pipeline (L3) is adapted to guide the subcritical cold water; The first heat exchanger (6) is heat-exchangeably disposed between the energy storage pipeline (L1) and the subcooling pipeline (L3); The first pressure regulating component (7) is directly or indirectly connected to the cold storage tank (4) and is suitable for regulating the water pressure of the cold subcritical water; A superheated pipeline (L4) connects the cold storage tank (4) and the heat storage tank (5), and the superheated pipeline (L4) is adapted to guide the subcritical thermal water; The second heat exchanger (8) is heat-exchangeably disposed between the energy release pipeline (L2) and the superheated pipeline (L4); The second pressure regulating component (9) is directly or indirectly connected to the thermal storage tank (5) and is suitable for regulating the water pressure of the thermal subcritical water. The second pressure regulating component (9) is connected to the heat storage tank (5), and the second pressure regulating component (9) is adapted to regulate the water pressure of the cold subcritical water stored in the cold storage tank (4).

2. The subcritical water compression gas energy storage system of claim 1, wherein, The first pressure regulating component (7) is installed on the subcooled pipeline (L3) and is adapted to regulate the water pressure of the subcritical cold water discharged from the cold storage tank (4).

3. The subcritical water compression gas energy storage system of claim 1, wherein, It also includes a controller (10), which is communicatively connected to the first voltage regulating component (7) and the second voltage regulating component (9), respectively. The controller (10) is adapted to control the start and stop of the first voltage regulating component (7) or the second voltage regulating component (9).

4. The subcritical water compression gas energy storage system according to any one of claims 1 to 3, characterized in that, The superheated pipeline (L4) is equipped with a buffer tank (11) suitable for storing subcritical water. The buffer tank (11) is located above the altitude of the cold storage tank (4). A water turbine (1101) is installed at the outlet of the buffer tank (11). The water turbine (1101) is powered by a first generator (1102).

5. The subcritical water compressed gas energy storage system according to claim 3, characterized in that, The first pressure regulating component (7) is configured as a cold water pump (12).

6. The subcritical water compressed gas energy storage system according to claim 3, characterized in that, The second pressure regulating component (9) is configured as a nitrogen regulating tank (13), which includes a receiving cavity suitable for containing nitrogen and a piston suitable for compressing the receiving cavity, and the receiving cavity is connected to the heat storage tank (5).

7. The subcritical water compressed gas energy storage system according to claim 1, characterized in that, It also includes an atmospheric pressure nitrogen tank (14), which is connected to the cold storage tank (4), and the atmospheric pressure nitrogen tank (14) is adapted to introduce atmospheric pressure nitrogen into the cold storage tank (4); and / or The compression assembly (2) includes a compressor (201) and an electric motor (202) powered by the compressor (201), and the expansion assembly (3) includes an expander (301) and a second generator (302) powered by the expander (301).

8. A control method, said control method being applied to the subcritical water compressed gas energy storage system according to any one of claims 1-7, characterized in that, include: S1: Lower the water level in the heat storage tank (5) to the lowest level and adjust the second pressure regulating component (9) to make the internal pressure of the heat storage tank (5) 2.0 MPa; S2: Start the compression assembly (2), obtain the gas temperature T1 at the outlet of the compression assembly (2), obtain the water temperature T2 of the cold storage tank (4), and calculate the internal target pressure P1 of the heat storage tank (5) according to the following formula; S3: Adjust the second pressure regulating component (9) to make the internal pressure of the heat storage tank (5) reach P1; S4: Adjust the first pressure regulating component (7) to make the water pressure of the subcooling pipeline (L3) reach P1, and complete the initial adjustment of the subcritical water pressure; S5: When the gas temperature T1 at the outlet of the compression component (2) and the water temperature T2 in the cold storage tank (4) change, repeat S2-S4 to adjust the subcritical water pressure in real time.

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