A liquid air energy storage system and method coupled with photo-thermal and ultra-high temperature heat pumps

Abstract

The application relates to a liquid air energy storage system and method coupled with photothermal and ultra-high temperature heat pumps, which comprises a liquid air energy storage subsystem, a heat pump subsystem and a photothermal energy storage subsystem, the photothermal energy storage subsystem comprises a molten salt storage and conveying device, a molten salt steam heat exchange device, a steam turbine generator unit, a steam condensing device and a pump, the molten salt steam heat exchange device is provided with a steam generating part, the steam generating part is communicated with the steam turbine generator unit, the steam condensing device and the pump through a power generation circulating pipe to form a closed power generation circulating pipeline, the molten salt storage and conveying device and the molten salt steam heat exchange device are communicated through a molten salt circulating pipe to form a closed molten salt circulating pipeline, and the liquid air energy storage subsystem and the photothermal energy storage subsystem share the molten salt storage and conveying device.

Description

Technical Field

[0001] This invention relates to the field of liquid air energy storage technology, specifically to a liquid air energy storage system and method that couples photothermal and ultra-high temperature heat pumps. Background Technology

[0002] Liquid air energy storage systems (LAES) are based on cryogenic air liquefaction and cold storage technologies. In the energy storage phase, ambient air is compressed and liquefied using electrical energy, stored as a low-temperature, low-pressure, high-density liquid air. In the energy release and power generation phase, the liquid air is reheated and vaporized in a cold box, then heated in a heat exchanger before entering an expander to drive a generator, thus releasing electrical energy. LAES is a novel energy storage method that enables deep grid integration of new energy sources such as wind and solar power, rational absorption of off-peak electricity and various forms of waste heat resources, and stable output of various forms of energy, including cooling, heating, electricity, and industrial gas, when needed. However, currently, due to some waste heat, LAES systems still suffer from relatively low electro-electric efficiency.

[0003] Concentrated solar energy storage (CSP) uses mirrors to concentrate sunlight onto a solar collector, heating a heat transfer medium (such as molten salt) to a high temperature. This heat is then used to generate steam to drive a steam turbine generator set to produce electricity. The advantages of CSP include continuous and stable power supply, high security, and the ability to replace some of the regulation capabilities of thermal power plants. The disadvantage is that environmental factors limit the steam turbines in CSP plants from operating at full capacity, resulting in a shorter annual effective power generation period.

[0004] Currently, independent liquid air energy storage power stations suffer from high thermal storage costs due to the relatively low temperature of the heat storage medium but its large volume. In addition, a large amount of low-grade waste heat remains unutilized, resulting in low system-to-electric efficiency. Furthermore, due to various constraints such as weather conditions, solar thermal energy storage power stations experience periods where the turbines cannot operate at full capacity, resulting in a short annual effective power generation period. Summary of the Invention

[0005] The present invention aims to provide a liquid air energy storage system and method that couples solar thermal and ultra-high temperature heat pumps. The technical problems to be solved include at least how to improve the electro-electric efficiency of existing independent liquid air energy storage power station systems, reduce thermal storage costs, and extend the power generation time of solar thermal power stations.

[0006] To achieve the above objectives, the present invention provides a liquid air energy storage system coupled with solar thermal and heat pump, comprising a liquid air energy storage subsystem, a heat pump subsystem, and a solar thermal energy storage subsystem. The solar thermal energy storage subsystem includes a molten salt storage and transportation device, a molten salt steam heat exchange device, a steam turbine generator set, a steam condensation device, and a pump. The molten salt steam heat exchange device is equipped with a steam generation section, which is connected to the steam turbine generator set, the steam condensation device, and the pump through a power generation circulation pipe to form a closed power generation circulation pipeline. The molten salt storage and transportation device is connected to the molten salt steam heat exchange device through a molten salt circulation pipe to form a closed molten salt circulation pipeline. The liquid air energy storage subsystem and the solar thermal energy storage subsystem share the molten salt storage and transportation device.

[0007] Preferably, the liquid air energy storage subsystem includes, in sequence, an air compressor unit, an outlet cooler of the air compressor unit, a second air compressor unit, a first-stage outlet cooler of the second air compressor unit, a second-stage outlet cooler of the second air compressor unit, an air purification device, a cold storage device, a liquid air expander, a liquid air storage tank, and a liquid air pump, all connected by air pipes. The outlet of the liquid air pump is connected to the cold storage device through an outlet pipe.

[0008] Preferably, a control valve is installed on the air pipe between the air expander and the air storage tank.

[0009] Preferably, the liquid air energy storage subsystem further includes a regenerator, a compressed air preheater, and an air turbine unit connected in a closed loop via an air circulation pipe, and the cold storage device and the regenerator are connected via an air pipe.

[0010] Preferably, the outlet cooler of the air compressor unit is provided with a cooling heat exchange section, and the cooling heat exchange section is connected to the molten salt storage and conveying device through a molten salt cooling circulation pipe to form a closed molten salt heat exchange circulation pipeline.

[0011] Preferably, the second-stage cooler at the outlet of the two-stage air compressor unit is provided with a second-stage cooling heat exchange section, and the second-stage cooling heat exchange section is connected to the preheater, the heat transfer medium cooler and the heat transfer medium delivery pump through a second-stage cooling circulation pipe to form a closed second-stage heat transfer medium cooling circulation pipeline.

[0012] Preferably, the first cooler at the outlet of the two-stage air compressor unit is provided with a first cooling heat exchange section, and the first cooling heat exchange section is connected to the molten salt storage and conveying device through a first cooling circulation pipe to form a closed molten salt heat exchange circulation pipeline.

[0013] Preferably, the top of the liquid air storage tank is connected to the cold storage device via a top pipe.

[0014] Preferably, the outlets of the cold storage device and the regenerator are respectively connected to exhaust pipes to discharge the air that has completed heat exchange in the cold storage device and the regenerator to the outside.

[0015] Preferably, the compressed air preheater is provided with a compressed air preheating heat exchange section, and the compressed air preheating heat exchange section is connected to the molten salt storage and conveying device through a compressed air preheating circulation pipe to form a closed molten salt preheating circulation pipeline.

[0016] Preferably, the heat pump subsystem includes a compressor unit, a first cooler, a circulating gas expansion generator, a preheater, a heat transfer medium delivery pump, and a heat transfer medium cooler. The preheater is provided with a preheating heat exchange section, and the preheating heat exchange section is connected to the compressor unit, the first cooler, and the circulating gas expansion generator through a working fluid circulation pipe to form a closed heat pump circulation pipeline.

[0017] Preferably, the first-stage cooler is provided with a first-stage cooling heat exchange section, and the first-stage cooling heat exchange section is connected to the molten salt storage and conveying device through a first-stage cooling circulation pipe to form a closed first-stage molten salt heat exchange circulation pipeline.

[0018] Preferably, the circulating gas in the closed heat pump circulation pipeline includes air or nitrogen.

[0019] Preferably, the heat transfer medium in the closed second-stage heat transfer medium cooling circulation pipeline includes water or an aqueous solution of ethylene glycol.

[0020] Preferably, the heat transfer medium cooler in the heat pump subsystem includes a dry air cooler or a wet air cooler.

[0021] The present invention also provides a control method for a liquid air energy storage system coupled with photothermal and heat pump, comprising the following steps:

[0022] S1. In the energy storage stage, the liquid air energy storage subsystem uses renewable energy or off-peak electricity from the grid to drive a first-stage air compressor unit to compress ambient air. The compressed air is cooled by molten salt in the outlet cooler of the first-stage air compressor unit. The cooled air is then further compressed by a second-stage air compressor unit. The further compressed air is cooled by molten salt in the first-stage cooler at the outlet of the second-stage air compressor unit, and then cooled by the second-stage cooler at the outlet of the second-stage air compressor unit. The cooled air enters an air purification device to remove impurities, and then enters a cold storage device to absorb cold energy, cool, and liquefy. After exiting the cold storage device, the air is depressurized and expanded by a liquid air expander, and then throttled by a control valve to produce liquid air, which is stored in a liquid air storage tank. Part of the air flows back to the cold storage device to provide some cooling energy, thus completing the energy storage process of the liquid air energy storage subsystem.

[0023] S2. In the energy storage stage, the cold molten salt in the solar thermal energy storage subsystem is heated into hot molten salt in the outlet cooler of the first-stage air compressor unit, the first-stage cooler of the outlet of the second-stage air compressor unit, and the high-temperature cooler, and then stored in the molten salt storage and transportation device.

[0024] S3. In the energy storage stage, the heat transfer medium in the heat pump subsystem delivers the heat transfer medium to the second-stage cooler at the outlet of the two-stage air compressor unit for heat exchange and temperature increase. Then, it enters the preheater to heat and cool the circulating gas of the heat pump. The cooled heat transfer medium enters the heat transfer medium cooler for further cooling. After the circulating gas is heated and raised in the preheater, it is further heated and pressurized by the compressor. Then, it enters the first cooler to exchange heat with molten salt and cool. The cooled gas enters the circulating gas expansion generator set for expansion and power generation. The gas after de-temperature and depressurization enters the preheater for temperature increase.

[0025] S4. During the energy release phase, the liquid air in the liquid air storage tank of the liquid air energy storage subsystem is pressurized by the liquid air pump and then enters the cold storage device, where it is heated. At the same time, the cold storage device absorbs the cold energy of the liquid air, thus completing the storage of cold energy. The ambient temperature high-pressure air is heated in the regenerator and then enters the compressed air preheater for further heating by molten salt. After that, it drives the air turbine unit to rotate and do work, which in turn drives the generator to generate electricity and transmit it to the grid, thus completing the energy release process of the liquid air energy storage device.

[0026] S5. During the energy release phase, the molten salt in the molten salt storage and transportation device of the solar thermal energy storage subsystem is divided into two streams. One stream is used to generate steam by heat exchange in the molten salt steam heat exchange device, and the other stream is sent to the compressed air preheater in the liquid air energy storage subsystem to heat the air. Water is heated and vaporized into steam in the molten salt steam heat exchange device, and then enters the steam turbine generator set to expand and generate electricity. The expanded steam enters the steam condensation device for condensation, and then is pressurized by a water pump and sent back to the molten salt steam heat exchange device to complete the cycle.

[0027] Compared with the prior art, the beneficial effects of the present invention are:

[0028] Compared with existing technologies, the liquid air energy storage system of coupled solar thermal and ultra-high temperature heat pump described in this invention has several advantages. First, the liquid air energy storage subsystem shares the molten salt storage and transportation device with the solar thermal energy storage subsystem, which can reduce the heat storage cost of the liquid air energy storage power station. Second, the increased heat storage temperature improves the electro-electric efficiency of the liquid air energy storage power station system. Third, the use of ultra-high temperature heat pumps to recover low-grade waste heat improves energy utilization and reduces the inability of the solar thermal power station turbine to generate full power due to environmental factors, thus increasing the turbine's power generation time. Attached Figure Description

[0029] The accompanying drawings are provided to further understand the technical solutions of the present invention and constitute a part of the specification. They are used together with the specific embodiments of this application to explain the technical solutions of the present invention and do not constitute a limitation on the technical solutions of the present invention.

[0030] Figure 1 This is a schematic diagram of the liquid air energy storage system that couples photothermal and heat pumps according to the present invention.

[0031] Figure label:

[0032] 1: First-stage air compressor unit; 2: First-stage air compressor unit outlet cooler; 3: Second-stage air compressor; 4: Second-stage air compressor unit outlet first-stage cooler; 5: Second-stage air compressor unit outlet second-stage cooler; 6: Air purification unit; 7: Cold storage unit; 8: Liquid air expander; 9: Liquid air storage tank; 10: Liquid air pump; 11: Regenerator; 12: Compressed air preheater; 13: Air turbine unit; 21: Heat transfer medium transfer pump; 22: Preheater; 23: Heat transfer medium cooler; 31: Ultra-high temperature compressor unit; 32: High temperature cooler; 33: Circulating gas expander; 40: Molten salt storage and conveying device; 41: Molten salt steam heat exchanger; 42: Steam turbine generator set; 43: Steam condensation device; 44: Pump; 101: Control valve. Detailed Implementation

[0033] The invention is described in more detail below to aid in understanding it.

[0034] like Figure 1 As shown, the liquid air energy storage system of coupled solar thermal and ultra-high temperature heat pumps of the present invention includes a liquid air energy storage subsystem 100, an ultra-high temperature heat pump subsystem 200 (i.e., a heat pump subsystem), and a solar thermal energy storage subsystem 300. The solar thermal energy storage subsystem 300 includes a molten salt storage and transportation device 40, a molten salt steam heat exchange device 41, a steam turbine generator set 42, a steam condensation device 43, and a pump 44. The molten salt steam heat exchange device 41 is provided with a steam generation section. The steam generation section is connected to the steam turbine generator set 42, the steam condensation device 43, and the pump 44 through a power generation circulation pipe to form a closed power generation circulation pipeline. The molten salt storage and transportation device 40 and the molten salt steam heat exchange device 41 are connected to each other through a molten salt circulation pipe to form a closed molten salt circulation pipeline. The liquid air energy storage subsystem 100 and the solar thermal energy storage subsystem 300 share the molten salt storage and transportation device 40.

[0035] Preferably, the liquid air energy storage subsystem 100 includes, in sequence, an air compressor unit 1, an outlet cooler 2 of the air compressor unit, a second air compressor unit 3, a first-stage outlet cooler 4 of the second air compressor unit, a second-stage outlet cooler 5 of the second air compressor unit, an air purification device 6, a cold storage device 7, a liquid air expander 8, a liquid air storage tank 9, and a liquid air pump 10, the outlet of the liquid air pump 10 being connected to the cold storage device 7 via an outlet pipe.

[0036] Preferably, the top of the liquid air storage tank 9 is connected to the cold storage device 7 via a top pipe.

[0037] Preferably, a control valve 101 is provided on the air pipe between the air expander 8 and the air storage tank 9.

[0038] Preferably, the liquid air energy storage subsystem 100 further includes a regenerator 11, a compressed air preheater 12, and an air turbine unit 13 connected to form a closed loop via an air circulation pipe, and the cold storage device 7 is connected to the regenerator 11 via an air pipe.

[0039] Preferably, the outlets of the cold storage device 7 and the regenerator 11 are respectively connected to exhaust pipes, which are used to discharge the air that has completed heat exchange in the cold storage device 7 and the regenerator 11 to the outside.

[0040] Preferably, the outlet cooler 2 of the air compressor unit is provided with a cooling heat exchange section, and the cooling heat exchange section is connected to the molten salt storage and conveying device 40 through a molten salt cooling circulation pipe to form a closed molten salt heat exchange circulation pipeline.

[0041] Preferably, the first-stage cooler 4 at the outlet of the two-stage air compressor unit is provided with a first-stage cooling heat exchange section, and the first-stage cooling heat exchange section is connected to the molten salt storage and conveying device 40 through a first-stage cooling circulation pipe to form a closed molten salt heat exchange circulation pipeline.

[0042] Preferably, the second-stage cooler 5 at the outlet of the two-stage air compressor unit is provided with a second-stage cooling heat exchange section. The second-stage cooling heat exchange section is connected to the preheater 22, the heat transfer medium cooler 23 and the heat transfer medium delivery pump 21 through a second-stage cooling circulation pipe to form a closed second-stage heat transfer medium cooling circulation pipeline.

[0043] Preferably, the compressed air preheater 12 is provided with a compressed air preheating heat exchange section, and the compressed air preheating heat exchange section is connected to the molten salt storage and conveying device 40 through a compressed air preheating circulation pipe to form a closed molten salt preheating circulation pipeline.

[0044] Preferably, the ultra-high temperature heat pump subsystem 200 (i.e., heat pump subsystem) includes an ultra-high temperature compressor unit 31 (i.e., compressor unit), a high temperature cooler 32 (i.e., first cooler), a circulating gas expansion generator 33, a preheater 22, a heat transfer medium delivery pump 21, and a heat transfer medium cooler 23. The preheater 22 is provided with a preheating heat exchange section. The preheating heat exchange section is connected to the ultra-high temperature compressor unit 31, the high temperature cooler 32, and the circulating gas expansion generator 33 through a working fluid circulation pipe to form a closed heat pump circulation pipeline.

[0045] Preferably, the circulating gas in the ultra-high temperature heat pump subsystem (i.e., the circulating gas in the closed heat pump circulation pipeline) includes, but is not limited to, air, nitrogen, etc.

[0046] Preferably, the heat transfer medium in the ultra-high temperature heat pump subsystem (i.e., the heat transfer medium in the closed second-stage heat transfer medium cooling circulation pipeline) includes, but is not limited to, water, ethylene glycol aqueous solution, etc.

[0047] Preferably, the heat transfer medium cooler 23 in the ultra-high temperature heat pump subsystem includes, but is not limited to, dry air coolers, wet air coolers, etc.

[0048] Preferably, the high-temperature cooler 32 (i.e., the first cooler) is provided with a cooling heat exchange section, and the cooling heat exchange section is connected to the molten salt storage and conveying device 40 through a cooling circulation pipe to form a closed molten salt heat exchange circulation pipeline.

[0049] The present invention also provides a control method for a liquid air energy storage system coupled with photothermal and heat pump, comprising the following steps:

[0050] S1. In the energy storage stage, the liquid air energy storage subsystem uses new energy sources such as wind power and photovoltaic power or off-peak electricity from the power grid to drive a first-stage air compressor unit 1 to compress ambient air to a high temperature and medium pressure. The high temperature compressed air is then cooled to a medium temperature by molten salt at the outlet of the first-stage air compressor unit 2. The medium temperature and medium pressure air is then further compressed to a high temperature and high pressure by a second-stage air compressor unit 3. The high temperature and high pressure air is cooled by molten salt at the outlet of the second-stage air compressor unit 4, and then cooled to a slightly higher temperature than the ambient temperature by the outlet of the second-stage air compressor unit 5. The cooled high pressure air enters the air purification device 6 to remove impurities with high freezing point temperatures, such as water and carbon dioxide. Then it enters the cold storage device 7 to absorb cold energy, cool to a low temperature, and liquefy. After exiting the cold storage device 7, the low temperature and high pressure air is depressurized and expanded by the liquid air expander 8, and then throttled by the control valve 101 to produce low temperature and low pressure liquid air, which is stored in the liquid air storage tank 9. The low temperature gaseous air flows back to the cold storage device 7 to provide some cooling energy, thus completing the energy storage process of the liquid air energy storage subsystem.

[0051] S2. In the energy storage stage, the cold molten salt in the solar thermal energy storage subsystem is heated into hot molten salt in the first-stage air compressor unit outlet cooler 2, the second-stage air compressor unit outlet first-stage cooler 4 and high-temperature cooler 32 and stored in the molten salt storage and conveying device 40.

[0052] S3. In the energy storage stage, the heat transfer medium transport pump 21 in the ultra-high temperature heat pump subsystem transports the heat transfer medium to the second-stage cooler 5 at the outlet of the second-stage air compressor unit for heat exchange and temperature increase. Then, it enters the preheater 22 to heat and cool the circulating gas of the ultra-high temperature heat pump. The cooled heat transfer medium enters the heat transfer medium cooler 23 for further cooling. After the circulating gas is heated and raised in the preheater 22, it is further heated and pressurized by the ultra-high temperature compressor 31. Then, it enters the high temperature cooler 32 to exchange heat with the cold molten salt and cool to the medium temperature. The cooled high-pressure gas enters the circulating gas expansion generator set 33 for expansion and power generation. The gas after de-temperatureing and depressurization enters the preheater 22 for temperature increase.

[0053] S4. During the energy release phase, the liquid air in the liquid air storage tank 9 of the liquid air energy storage subsystem is pressurized by the liquid air pump 10 and enters the cold storage device 7. The cold storage device 7 is heated to room temperature and absorbs the cold energy of the liquid air to complete the storage of cold energy. The room temperature high-pressure air is heated in the regenerator 11 and then enters the compressed air preheater 12, where it is further heated by hot molten salt to become high temperature and high pressure air. After that, it drives the air turbine unit 13 to rotate and do work, which further drives the generator to generate electricity and transmit it to the grid, thus completing the energy release process of the liquid air energy storage device.

[0054] S5. During the energy release phase, the hot molten salt in the molten salt storage and transportation device 40 of the solar thermal energy storage subsystem is divided into two streams. One stream is used to generate high-temperature and high-pressure steam by heat exchange in the molten salt steam heat exchange device 41, and the other stream is sent to the compressed air preheater 12 in the liquid air energy storage subsystem to heat the air. Water is heated and vaporized into high-temperature and high-pressure steam in the molten salt steam heat exchange device 41, and then enters the steam turbine generator set 42 to expand and generate electricity. The expanded low-temperature and low-pressure steam enters the steam condensing device 43 for condensation, and then is pressurized by the water pump 44 and sent back to the molten salt steam heat exchange device 41 to complete the cycle.

[0055] The beneficial effects of this invention are as follows: compared with the prior art, on the one hand, the liquid air energy storage subsystem and the solar thermal energy storage subsystem share the molten salt storage and transportation device, reducing the heat storage cost of the liquid air energy storage power station; on the other hand, the increase in heat storage temperature improves the electro-electric efficiency of the liquid air energy storage power station system; in addition, the use of ultra-high temperature heat pumps to recover low-grade waste heat improves energy utilization and reduces the amount of solar thermal power station turbine power generation caused by environmental factors, increasing the turbine power generation time.

[0056] The core idea of ​​the liquid air energy storage system method for coupled solar thermal and ultra-high temperature heat pumps described in this invention is as follows: The liquid air energy storage subsystem uses off-peak electricity or new energy power for energy storage, and then enters a resting period, waiting to release energy and generate electricity during peak electricity demand. In addition, the solar thermal energy storage subsystem shares the molten salt storage and transportation device; the ultra-high temperature heat pump system recovers the low-grade waste heat generated by the second-stage air compressor during the energy storage stage and uses off-peak electricity or new energy power to heat the cold molten salt into hot molten salt; the solar thermal energy storage subsystem uses the hot molten salt generated by the ultra-high temperature heat pump subsystem as a supplementary heat source. During the energy release and power generation stage, the hot molten salt heats the water in the solar thermal energy storage subsystem to vaporize into high-temperature and high-pressure steam to drive the steam turbine to generate electricity, increasing the power generation time.

[0057] The preferred embodiments of the present invention have been described above, but are not intended to limit the invention. Those skilled in the art can make modifications and variations to the embodiments disclosed herein without departing from the scope and spirit of the invention.

Claims

1. A liquid air energy storage system coupled with photothermal and heat pump, characterized in that, The aforementioned liquid air energy storage system coupled with solar thermal and heat pumps includes a liquid air energy storage subsystem, a heat pump subsystem, and a solar thermal energy storage subsystem. The solar thermal energy storage subsystem includes a molten salt storage and transport device, a molten salt steam heat exchange device, a steam turbine generator set, a steam condensation device, and a pump. The molten salt steam heat exchange device is equipped with a steam generation section, which is connected to the steam turbine generator set, the steam condensation device, and the pump via a power generation circulation pipe to form a closed power generation circulation pipeline. The molten salt storage and transport device is connected to the molten salt steam heat exchange device via a molten salt circulation pipe to form a closed molten salt circulation pipeline. The liquid air energy storage subsystem and the solar thermal energy storage subsystem share the molten salt storage and transport device. The liquid air energy storage subsystem includes, in sequence, an air compressor unit, an outlet cooler of the air compressor unit, a second air compressor unit, a first-stage outlet cooler of the second air compressor unit, a second-stage outlet cooler of the second air compressor unit, an air purification device, a cold storage device, a liquid air expander, a liquid air storage tank, and a liquid air pump, all connected by air pipes. The outlet of the liquid air pump is connected to the cold storage device through an outlet pipe. The liquid air energy storage subsystem also includes a regenerator, a compressed air preheater, and an air turbine unit connected in a closed loop via air circulation pipes. The cold storage device and the regenerator are connected via an air pipe. The outlet cooler of the air compressor unit is provided with a cooling heat exchange section, and the cooling heat exchange section is connected to the molten salt storage and conveying device through a molten salt cooling circulation pipe to form a closed molten salt heat exchange circulation pipeline. The compressed air preheater is provided with a compressed air preheating heat exchange section, and the compressed air preheating heat exchange section is connected to the molten salt storage and conveying device through a compressed air preheating circulation pipe to form a closed molten salt preheating circulation pipeline. The second-stage cooler at the outlet of the two-stage air compressor unit is provided with a second-stage cooling heat exchange section. The second-stage cooling heat exchange section is connected to the preheater, the heat transfer medium cooler and the heat transfer medium delivery pump through a second-stage cooling circulation pipe to form a closed second-stage heat transfer medium cooling circulation pipeline. The heat pump subsystem includes a compressor unit, a first cooler, a circulating gas expansion generator, a preheater, a heat transfer medium delivery pump, and a heat transfer medium cooler. The preheater is equipped with a preheating heat exchange section, and the preheating heat exchange section is connected to the compressor unit, the first cooler, and the circulating gas expansion generator through a working fluid circulation pipe to form a closed heat pump circulation pipeline. The first cooler is provided with a first-stage cooling heat exchange section, and the first-stage cooling heat exchange section is connected to the molten salt storage and conveying device through a first-stage cooling circulation pipe to form a closed molten salt first-stage molten salt heat exchange circulation pipeline.

2. The liquid air energy storage system coupled with photothermal and heat pump according to claim 1, characterized in that, A control valve is installed on the air pipe between the air expander and the air storage tank.

3. The liquid air energy storage system coupled with photothermal and heat pump according to claim 1, characterized in that, The first-stage cooler at the outlet of the two-stage air compressor unit is equipped with a first-stage cooling heat exchange section. The first-stage cooling heat exchange section is connected to the molten salt storage and conveying device through a first-stage cooling circulation pipe to form a closed first-stage molten salt heat exchange circulation pipeline.

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