Solid-liquid phase double-coupled liquid air energy and cold storage system

Abstract

The utility model discloses a solid-phase and liquid-phase double-coupled liquid air energy storage and cold storage system. Comprising an air liquefaction storage module used for cooling, liquefying and storing compressed air, a liquid phase cold storage / release module used for storing and releasing high-quality cooling capacity of liquid air, and a solid phase cold storage / release module used for storing and releasing medium-low-quality cooling capacity of the liquid air. The liquid phase cold storage / release module and the solid phase cold storage / release module are connected to the rear end of the air liquefaction storage module in series, and heat exchange is conducted between the liquid phase cold storage / release module and the air liquefaction storage module and between the solid phase cold storage / release module and the air liquefaction storage module. High-quality cooling capacity in the power generation process of the liquid air energy storage system is stored in a liquid-phase cold storage mode, medium-low-quality cooling capacity in the power generation process of the liquid air energy storage system is stored in a solid-phase cold storage mode, the defect of large exergy loss caused by solid-phase cold storage is overcome, and the cold storage efficiency of the energy storage system is improved.

Description

Technical Field

[0001] This utility model relates to the field of liquid air energy storage technology, and more specifically to a liquid air energy storage and cooling system with solid-liquid phase dual coupling. Background Technology

[0002] As my country accelerates its energy structure transformation towards low-carbon and clean energy, the proportion of new energy power generation, represented by wind power and photovoltaic power, in the energy structure continues to rise. However, the intermittent and fluctuating characteristics of new energy power generation and large-scale grid connection pose severe challenges to the peak-shaving, frequency regulation, safe and stable operation of the power system, making the demand for flexible power sources for the power system increasingly urgent. As a key support for energy transformation, energy storage technology can effectively smooth out the fluctuations in new energy output and improve the flexibility and reliability of the power grid.

[0003] Liquid air energy storage, as a novel physical energy storage technology, boasts advantages such as high energy density, long service life, environmental friendliness, and strong geographical adaptability. It is considered a potential solution to support future high-proportion renewable energy power systems. As a core component of liquid air energy storage systems, the operating characteristics and efficiency of the cold storage system significantly impact the overall efficiency and reliability of the system. Currently, there are few mature cases of cold energy storage and release below -150℃. The main limiting factor is the cold storage medium. While solid-phase cold storage media such as marble, granite, and ceramics are relatively inexpensive, they require secondary transfer of cold energy using a circulating medium, resulting in significant exergy losses, especially in the high-quality portion. Among liquid-phase cold storage media, there are few selectable materials, as there are not many working fluids existing in liquid form within the temperature range below -150℃. Currently, a two-stage liquid-phase cold storage system using methanol and propane is feasible, achieving high cold storage efficiency. However, since both methanol and propane are flammable and explosive media, this introduces numerous safety hazards to liquid air energy storage systems, limiting their application scope in many scenarios, such as densely populated areas and load centers. Therefore, it is necessary to improve and optimize liquid air energy storage and cold storage systems to achieve high efficiency while avoiding the use of flammable and explosive media, and to expand the application scenarios of energy storage systems. Utility Model Content

[0004] The technical problem to be solved by this utility model is to provide a liquid air energy storage and cold storage system with solid-liquid phase dual coupling. It aims to solve the problems of low efficiency and significant loss of high-quality cold energy in the cold storage system during solid phase cold storage. The system uses liquid phase cold storage to store high-quality cold energy and solid phase cold storage to store medium and low-quality cold energy, thereby improving system efficiency and enhancing the safety of the energy storage system.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by this utility model is as follows.

[0006] A solid-liquid phase dual-coupling liquid air energy storage and cooling system includes an air liquefaction storage module for cooling and liquefying compressed air, a liquid phase cold storage / release module for storing and releasing high-quality cold energy of liquid air, and a solid phase cold storage / release module for storing and releasing medium- and low-quality cold energy of liquid air. The liquid phase cold storage / release module and the solid phase cold storage / release module are connected in series at the rear end of the air liquefaction storage module, and the liquid phase cold storage / release module and the solid phase cold storage / release module exchange heat with the air liquefaction storage module respectively.

[0007] To further optimize the technical solution, the air liquefaction and storage module includes a first liquefaction main heat exchanger and a second liquefaction main heat exchanger connected in series for cooling compressed air. The liquid air pipeline of the second liquefaction main heat exchanger is connected to a liquid air storage tank for storing liquid air via a gas-liquid separator. The low-temperature reflux gas pipe of the gas-liquid separator is connected to the first liquefaction main heat exchanger and the second liquefaction main heat exchanger in sequence. A throttling valve for depressurizing the liquid air flowing out of the second liquefaction main heat exchanger is installed on the pipeline between the second liquefaction main heat exchanger and the gas-liquid separator.

[0008] The technical solution is further optimized. The liquid phase cold storage / release module includes a first evaporator located after the air liquefaction storage module for heat exchange with low-temperature liquid air, and a first liquid phase cold storage tank and a second liquid phase cold storage tank for storing the cold storage medium. A low-temperature pump for pressurizing the stored liquid air is provided between the first evaporator and the air liquefaction storage module. The liquid air output end of the first evaporator is connected to the solid phase cold storage / release module. The first liquid phase cold storage tank is connected to the heat exchange inlet end of the first evaporator through a low-temperature cold storage pump, and the second liquid phase cold storage tank is connected to the heat exchange outlet end of the first evaporator. The first liquid phase cold storage tank and the second liquid phase cold storage tank are connected to the air liquefaction storage module through a low-temperature cold release pump to release cold energy.

[0009] The technical solution is further optimized so that the low-temperature cold storage medium stored in the first liquid phase cold storage tank and the second liquid phase cold storage tank are both low-temperature liquid working fluids. The temperature of the working fluid in the first liquid phase cold storage tank is higher than that in the second liquid phase cold storage tank. The temperature of the working fluid in both the first liquid phase cold storage tank and the second liquid phase cold storage tank is lower than the saturation temperature of the liquid phase cold storage medium corresponding to the operating pressure of the liquid phase cold storage / release module.

[0010] To further optimize the technical solution, the solid phase cold storage / release module includes a second evaporator connected in series with the liquid phase cold storage / release module and a solid phase cold storage packed bed connected to the heat exchange end of the second evaporator for storing the cold energy of low-temperature air. The two ends of the solid phase cold storage packed bed are connected to the air liquefaction storage module to realize the release of cold energy.

[0011] To further optimize the technical solution, the solid-phase cold storage filling bed is equipped with a top control valve and a bottom control valve.

[0012] The technological advancements achieved by this utility model are as follows, due to the adoption of the above technical solutions.

[0013] This invention provides a solid-liquid phase dual-coupling liquid air energy storage and cooling system. It utilizes liquid-phase cooling to store high-quality cooling energy generated during the power generation process of the liquid air energy storage system, and solid-phase cooling to store medium- and low-quality cooling energy generated during the same process. This overcomes the drawback of significant exergy loss caused by solid-phase cooling, thus improving the cooling efficiency of the energy storage system. The selected liquid-phase cooling medium is a non-flammable and non-explosive liquid working fluid such as liquid air, liquid argon, or liquid nitrogen at a certain pressure. Compared with liquid-phase cooling systems using hydrocarbons and alcohols, this improves the safety of the cooling system and expands the application scenarios of liquid air energy storage. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of this utility model.

[0015] The components are: 1. First liquefaction main heat exchanger, 2. Second liquefaction main heat exchanger, 3. Throttling valve, 4. Gas-liquid separator, 5. Liquid air storage tank, 6. Cryogenic pump, 7. First evaporator, 8. Second liquid phase cold storage tank, 9. Cryogenic cold release pump, 10. First liquid phase cold storage tank, 11. Cryogenic cold storage pump, 12. Second evaporator, 13. Top control valve of packed bed, 14. Bottom control valve of packed bed, and 15. Solid phase cold storage packed bed. Detailed Implementation

[0016] The present invention will now be described in further detail with reference to the accompanying drawings and specific embodiments.

[0017] A solid-liquid phase dual-coupling liquid air energy storage and cooling system, combined with Figure 1 As shown, it includes an air liquefaction storage module, a liquid phase cold storage / release module, and a solid phase cold storage / release module. The liquid phase cold storage / release module and the solid phase cold storage / release module are connected in series at the rear end of the air liquefaction storage module. The liquid phase cold storage / release module and the solid phase cold storage / release module exchange heat with the air liquefaction storage module respectively. The outlet pipe of the solid phase cold storage / release module is connected to a heater to heat the compressed air.

[0018] The air liquefaction and storage module cools, liquefies, and stores compressed air during operation. The module includes a first liquefaction main heat exchanger 1 and a second liquefaction main heat exchanger 2 connected in series. The first and second heat exchangers 1 and 2 are used to cool the compressed air. A liquid air storage tank 5 is connected to the liquid air pipeline of the second heat exchanger 2 via a gas-liquid separator 4 for storing liquid air. A low-temperature reflux pipe of the gas-liquid separator 4 is sequentially connected to the first and second heat exchangers 1 and 2. A throttling valve 3 is installed on the pipeline between the second heat exchanger 2 and the gas-liquid separator 4 to reduce the pressure of the liquid air flowing out of the second heat exchanger 2. The high-pressure liquid air flowing out of the second heat exchanger 2, after being depressurized by the throttling valve 3, passes through the gas-liquid separator 4 and is stored in the liquid air storage tank 5 in a lower-pressure liquid form.

[0019] During operation, the compressed air in the air liquefaction storage module absorbs cold energy by passing through the first liquefaction main heat exchanger 1 and the second liquefaction main heat exchanger 2 in sequence; correspondingly, the low-temperature reflux gas from the gas-liquid separator 4 releases cold energy by passing through the second liquefaction main heat exchanger 2 and the first liquefaction main heat exchanger 1 in sequence.

[0020] The first liquefaction main heat exchanger 1 and the second liquefaction main heat exchanger 2 in the air liquefaction storage module can be arranged as two or more units, or they can be combined into one unit, depending on the specific process parameters. In this embodiment, the first liquefaction main heat exchanger 1 and the second liquefaction main heat exchanger are arranged as two units for illustration.

[0021] The liquid-phase cold storage / release module is used to store and release high-quality cold energy from liquid air during operation. It includes a cryogenic pump 6, a first evaporator 7, a first liquid-phase cold storage tank 10, and a second liquid-phase cold storage tank 8. The cryogenic pump 6 is located downstream of the liquid air storage tank 5 to pressurize the liquid air. The first evaporator 7 is located downstream of the cryogenic pump 6 to exchange heat with the cryogenic liquid air. The first evaporator 7 is connected to the solid-phase cold storage / release module. The first liquid-phase cold storage tank 10 and the second liquid-phase cold storage tank 8 are used to store the cold storage medium. The first liquid-phase cold storage tank 10 is connected to the heat exchange inlet of the first evaporator 7 via a cryogenic cold storage pump 11, and the second liquid-phase cold storage tank 8 is connected to the heat exchange outlet of the first evaporator 7. The first liquid-phase cold storage tank 10 and the second liquid-phase cold storage tank 8 are connected to the second liquefaction main heat exchanger 2 via a cryogenic cold release pump 9 to release the cold energy.

[0022] During the cold storage process, the cold storage medium in the first liquid phase cold storage tank 10 enters the first evaporator 7 after passing through the low-temperature cold storage pump 11 and exchanges heat with the low-temperature liquid air. Then, it enters the second liquid phase cold storage tank 8 to complete one cold storage cycle. The outlet of the second liquid phase cold storage tank 8 is connected to the inlet of the low-temperature cold release pump 9. During the cold release process, the cold storage medium in the second liquid phase cold storage tank 8 enters the second liquefaction main heat exchanger 2 after passing through the low-temperature cold release pump 9 to release the cold energy. Then, it enters the first liquid phase cold storage tank 10 to complete one cold release cycle.

[0023] The low-temperature cold storage medium stored in the first liquid phase cold storage tank 10 and the second liquid phase cold storage tank 8 is a low-temperature liquid working medium. The temperature of the working medium in the first liquid phase cold storage tank 10 is higher than the temperature of the working medium in the second liquid phase cold storage tank 8. The temperatures of the working medium in the first liquid phase cold storage tank 10 and the second liquid phase cold storage tank 8 are both lower than the saturation temperature of the liquid phase cold storage medium corresponding to the operating pressure of the liquid phase cold storage / release module.

[0024] In the liquid phase cold storage / release module, the cold storage medium is not limited to any non-flammable and non-explosive cryogenic liquid medium such as liquid air, liquid nitrogen, or liquid argon.

[0025] The solid-phase cold storage / release module is used to store and release medium-to-low quality cold energy of liquid air during operation. It includes a second evaporator 12 and a solid-phase cold storage packed bed 15. The second evaporator 12 is connected in series after the first evaporator 7. The solid-phase cold storage packed bed 15 is connected to the heat exchange end of the second evaporator 12 to store low-temperature air cold energy. The solid-phase cold storage packed bed 15 is connected to the first liquefaction main heat exchanger 1 to release the cold energy. The solid-phase cold storage packed bed 15 is equipped with a top control valve 13 and a bottom control valve 14.

[0026] When the system is storing cold, the circulating medium in the solid-phase cold storage bed 15 flows from bottom to top, then exchanges heat with the low-temperature air in the second evaporator 12 to absorb cold energy, and then returns to the solid-phase cold storage bed 15 to transfer the cold energy to the solid-phase cold storage medium, completing the cold storage cycle. Correspondingly, when the system is releasing cold, the circulating medium in the solid-phase cold storage bed 15 flows from top to bottom, exchanges heat with the compressed air in the first liquefaction main heat exchanger 1 to release cold energy, and then returns to the solid-phase cold storage bed 15 to complete the cold release cycle.

[0027] In the solid-phase cold storage / release module, the cold storage medium is not limited to solid media such as stone, ceramics, and metals, and the selected circulation medium is not limited to media such as air and nitrogen. Correspondingly, the cold storage / release temperature in the liquid-phase cold storage / release module is lower than the cold storage / release temperature in the solid-phase cold storage / release module during the cold storage and release processes.

[0028] The second evaporator 12 connected to the first evaporator 7 can be configured as two or more evaporators, or they can be combined into one evaporator arrangement.

Claims

1. A liquid air energy storage and cold storage system with solid-liquid phase dual coupling, characterized in that: It includes an air liquefaction storage module for cooling and liquefying compressed air, a liquid phase cold storage / release module for storing and releasing high-quality cold energy of liquid air, and a solid phase cold storage / release module for storing and releasing medium- and low-quality cold energy of liquid air. The liquid phase cold storage / release module and the solid phase cold storage / release module are connected in series at the rear end of the air liquefaction storage module, and the liquid phase cold storage / release module and the solid phase cold storage / release module exchange heat with the air liquefaction storage module respectively.

2. The liquid air energy storage and cold storage system with solid-liquid phase dual coupling according to claim 1, characterized in that: The air liquefaction storage module includes a first liquefaction main heat exchanger (1) and a second liquefaction main heat exchanger (2) connected in series for cooling compressed air. The liquid air pipeline of the second liquefaction main heat exchanger (2) is connected to a liquid air storage tank (5) for storing liquid air through a gas-liquid separator (4). The low-temperature reflux gas pipe of the gas-liquid separator (4) is connected to the first liquefaction main heat exchanger (1) and the second liquefaction main heat exchanger (2) in sequence. A throttle valve (3) is provided on the pipeline between the second liquefaction main heat exchanger (2) and the gas-liquid separator (4) for depressurizing the liquid air flowing out of the second liquefaction main heat exchanger (2).

3. The liquid air energy storage and cold storage system with solid-liquid phase dual coupling according to claim 1, characterized in that: The liquid phase cold storage / release module includes a first evaporator (7) located behind the air liquefaction storage module for exchanging heat with low-temperature liquid air, and a first liquid phase cold storage tank (10) and a second liquid phase cold storage tank (8) for storing the cold storage medium. A low-temperature pump (6) for pressurizing the stored liquid air is provided between the first evaporator (7) and the air liquefaction storage module. The liquid air output end of the first evaporator (7) is connected to the solid phase cold storage / release module. The first liquid phase cold storage tank (10) is connected to the heat exchange inlet end of the first evaporator (7) through a low-temperature cold storage pump (11), and the second liquid phase cold storage tank (8) is connected to the heat exchange outlet end of the first evaporator (7). The first liquid phase cold storage tank (10) and the second liquid phase cold storage tank (8) are connected to the air liquefaction storage module through a low-temperature cold release pump (9) to realize the release of cold energy.

4. The liquid air energy storage and cold storage system with solid-liquid phase dual coupling according to claim 3, characterized in that: The low-temperature cold storage medium stored in the first liquid phase cold storage tank (10) and the second liquid phase cold storage tank (8) is a low-temperature liquid working medium. The temperature of the working medium in the first liquid phase cold storage tank (10) is higher than the temperature of the working medium in the second liquid phase cold storage tank (8). The temperatures of the working medium in the first liquid phase cold storage tank (10) and the second liquid phase cold storage tank (8) are both lower than the saturation temperature of the liquid phase cold storage medium corresponding to the operating pressure of the liquid phase cold storage / release module.

5. The liquid air energy storage and cold storage system with solid-liquid phase dual coupling according to claim 1, characterized in that: The solid phase cold storage / release module includes a second evaporator (12) connected in series with the liquid phase cold storage / release module and a solid phase cold storage bed (15) connected to the heat exchange end of the second evaporator (12) for storing the cold energy of low-temperature air. The two ends of the solid phase cold storage bed (15) are connected to the air liquefaction storage module to realize the release of cold energy.

6. The liquid air energy storage and cold storage system with solid-liquid phase dual coupling according to claim 5, characterized in that: The solid-phase cold storage packed bed (15) is equipped with a top control valve (13) and a bottom control valve (14).

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