A device and method for coupling liquefied air energy storage and cryogenic air separation

Abstract

A device and method for coupling liquefied air energy storage and cryogenic air separation, wherein the device comprises an air liquefaction energy storage subsystem, a liquefied air power generation and energy release and cryogenic air separation coupling subsystem; during the period of sufficient renewable energy power generation (photovoltaic, wind power, etc.) or valley power, the air liquefaction energy storage subsystem and the cryogenic air separation subsystem operate independently of each other: after the air is compressed and cooled and liquefied by a compressor, the liquid air is stored in a liquid air storage tank through a gas-liquid separator; the heat generated during the compression process is stored in a heat storage tank, a part of this heat is used as the heat source required for the liquid air energy release stage, and the excess heat is directly or indirectly used for heating or electricity supply to industry and commerce; the present invention reduces the dependence of power-intensive air separation equipment on power grid electricity through large-scale utilization of valley power or intermittent renewable "green electricity", saves production electricity costs, and has good corporate economic benefits and national energy conservation and emission reduction benefits.

Description

Technical Field

[0001] The present invention relates to the technical field of energy conversion and air separation energy storage, and in particular to a device and method for coupling liquefied air energy storage and cryogenic air separation. Background Art

[0002] In order to balance the relationship between regional power load and supply, large-scale and long-term energy storage technology has become the main direction of current power technology research. Among many energy storage technologies, compared with pumped storage and electrochemical energy storage, liquid air energy storage has outstanding advantages such as low initial investment, high energy storage density, large scale, long energy storage time, clean and low carbon, safe, long life and no geographical restrictions, and has a wide range of application scenarios, especially in the fields of renewable energy consumption, grid peak and frequency regulation, distributed energy, and integrated energy services. However, due to the large number of liquefied air energy storage system equipment and the relatively complex system, the conventional liquefied air energy storage cycle efficiency is low, generally 40~50%. In addition, the high-purity air environment released after the expansion of power generation during the energy release process causes a waste of resources. Therefore, in view of the problems of high-purity air environment release after the liquefied air energy storage system releases energy, low electricity-to-electricity conversion efficiency, large compressor pressure ratio at each stage, and long cost recovery period, improving the overall cycle efficiency of the system has become the focus and difficulty of current research in universities and enterprises.

[0003] Cryogenic air separation is an important basic equipment in the field of industrial production, including compression, precooling, purification, pressurization, refrigeration, heat exchange and distillation. The refrigeration temperature is equivalent to that of liquefied air energy storage technology, and the raw material for production is ambient air. It is worth noting that the air separation equipment itself consumes a lot of electricity. Due to the improvement of the time-sharing electricity price mechanism, the price difference between peak and valley electricity prices has further widened, and its electricity consumption accounts for a considerable proportion. For example, by combining liquefied air energy storage technology with conventional air separation devices, the refrigeration energy levels of the two technologies can be accurately matched, and the raw materials can be used complementary, that is, the problem of high-purity air emissions in the energy release process of the liquefied air energy storage system can be overcome, and high-purity air raw materials with external pressure matching can be provided for air separation equipment, reducing the comprehensive electricity cost of air separation enterprises and improving economic benefits. In addition, the coupling integration of the two can also fundamentally solve the low electrical cycle efficiency of conventional liquefied air energy storage technology, and the improvement of electricity consumption during the valley period is also conducive to improving the operating efficiency of the generator set and reducing the peak power load demand.

[0004] Patent CN114383384A proposes an integrated method of air liquefaction and cryogenic air separation process. The patent adopts a conventional air liquefaction energy storage process. In the liquefied air power generation process, the liquefied air after the cryogenic pump and the low-temperature high-pressure air are directly sent to the distillation tower in the cryogenic air separation equipment for distillation, thereby recovering the cold and material of the liquefied air and improving the electric-to-electric conversion efficiency of the liquefied air energy storage. However, when the compression, precooling, purification, pressurization and refrigeration system loads of the cryogenic air separation unit are reduced accordingly, a complex control system that requires a fast response is added to the actual production air separation equipment, and the performance of the cryogenic distillation tower is disrupted. The gas product of the distillation is not fully reheated, and the main heat exchanger exceeds its load range, which has a negative impact on the operation of the equipment, which is not conducive to the accurate evaluation of the system and guiding it to be put into practical application. Summary of the invention

[0005] The technical problem to be solved by the present invention is: to provide a device and method for coupling liquefied air energy storage and cryogenic air separation, which is used to solve the problems of high power consumption of cryogenic air separation, low electricity-to-electricity conversion efficiency of conventional liquefied air energy storage, high-purity air venting loss in the energy release stage, and complicated control and load coupling between liquefied air energy storage and cryogenic air separation systems. When the two technologies are integrated and coupled with each other, the high-purity air in the energy release stage of the conventional liquefied air energy storage device can be efficiently and fully recovered and utilized in the cryogenic air separation system, and when the two types of systems are coupled, the operating mode of the cryogenic air separation system will not be changed and there is no need to reduce / increase load operation, which provides a strong guarantee for the stable operation of the entire air separation system; when the two technologies operate independently, the conventional operating states of the liquefied air energy storage device and the cryogenic air separation device are maintained respectively. Without changing the main process of the conventional cryogenic air device and the liquefied air energy storage device, the mutual coordination and independent operation of the two are achieved by adding control valves and the connecting pipes between them. To achieve the above-mentioned purpose, the present invention adopts: a device for coupling liquefied air energy storage and cryogenic air separation, which includes an air liquefaction energy storage subsystem and a liquefied air power generation and energy release and cryogenic air separation coupling subsystem, the air liquefaction energy storage subsystem includes a compressor, an interstage cooler, an aftercooler, a molecular sieve adsorber, an expansion refrigerator, a heat storage tank, a gas-liquid separator and a liquefied air storage tank, and each device is controlled by a valve and connected by a pipeline; the liquefied air power generation and energy release and cryogenic air separation coupling subsystem includes a low-temperature pump, an evaporator, a multi-stage reheater, an expansion generator matching the pressure of the compressor of the cryogenic air separation equipment, a high-purity air-waste heat utilization heat exchanger, and a cold storage tank, and each device is controlled by a valve and connected by a pipeline.

[0006] Preferably, the air liquefaction energy storage subsystem is further provided with a purification device of an aftercooler and a molecular sieve adsorber, which removes carbon dioxide and water from the air compressed by compressor I.

[0007] Preferably: the excess heat in the air liquefaction energy storage subsystem directly or indirectly provides heating or electricity for industry and commerce, and the compressed heat in the air liquefaction energy storage subsystem is recycled into two heat storage tanks in two levels, wherein the compressed heat with a temperature higher than 100 degrees Celsius is stored in heat storage tank I, and the compressed heat below 100 degrees Celsius is stored in heat storage tank II, providing a matching heat source for different forms of heat use; the excess heat in the air liquefaction energy storage subsystem is directly used in the high-purity air-waste heat utilization heat exchanger as a heat source for reheating the high-purity air extracted from the expansion generator and the final stage, wherein the gas extracted from the expansion generator is used as the pressurized feed gas for the deep-cold air separation subsystem, and the final stage high-purity air is used as the regeneration gas source for the molecular sieve adsorber.

[0008] Preferably, the compressor has a multi-stage structure, each compressor is connected to a cooler at the rear, and each stage of the compressor is connected to a group of aftercoolers to reduce the inlet air temperature of each stage of the compressor, thereby reducing the power consumption of the compressor.

[0009] Preferably, the cooler, evaporator, reheater, air liquefaction heat exchanger, and high-purity air-waste heat utilization heat exchanger are one or a combination of two or more of a plate structure, a plate-fin structure, a shell-and-tube structure, or a spiral structure, and the heat exchange mode is co-current, counter-current, or cross-current;

[0010] A method for coupling a liquefied air energy storage device with a cryogenic air separation device, the method comprising a time period when renewable energy generation is sufficient or valley power generation is required and a time period when renewable energy generation is insufficient or non-valley power generation is required, wherein during the time period when renewable energy generation is sufficient or valley power generation is required, the air liquefied energy storage subsystem and the cryogenic air separation subsystem operate independently of each other,

[0011] When renewable energy is scarce or during off-peak hours, the liquefied air power generation system and the deep-cold air separation subsystem are coupled and operated in a matching manner.

[0012] As a preferred method, the specific method of using the renewable energy during the period of sufficient power generation or off-peak power generation is as follows:

[0013] Step 1: The air in the air liquefaction energy storage subsystem first passes through the air filter and enters the compressor I for compression. The compressor I is matched with a corresponding interstage cooler, and the cooled air enters the aftercooler for cooling and dehumidification;

[0014] Step 2: The treated air is then sent to the molecular sieve adsorber for purification. The air that has further removed carbon dioxide and water enters compressor II for pressurization. Compressor II is matched with a corresponding interstage cooler. The pure air treated by the interstage cooler of compressor II is sent to the air liquefaction heat exchanger for liquefaction. A part of the pressurized air is expanded by the expansion refrigerator and then sent to the gas-liquid separator for gas-liquid separation. The unliquefied air is sent to the inlet of compressor II after the air liquefaction heat exchanger recovers the cold capacity to complete the air cycle.

[0015] Step 3: The liquefied air is sent to the liquefied air storage tank for storage, thus completing the high-purity air liquefaction energy storage process; the heat generated during the compression process is stored in heat storage tank I and heat storage tank II, and part of the stored heat is used as the heat source required for the liquefied air energy release process, and the excess heat is directly or indirectly used for heating or electricity for industry and commerce.

[0016] As a preferred method, the method of using the renewable energy shortage or non-peak electricity period is as follows:

[0017] Step 1: The liquefied air stored in the air liquefaction energy storage subsystem is pressurized by a cryogenic pump and sent to the evaporator for preheating. The cold energy of the liquefied air is recovered and stored in the cold storage tank and used as part of the cold energy in the air liquefaction process.

[0018] Step 2: The preheated high-pressure air is expanded and generated by an expansion generator that matches the pressure of the compressor of the cryogenic air separation equipment. The expansion generator matches a corresponding reheater. High-purity air is generated by the expansion generator and partially extracted from the expansion generator. The high-purity air extracted in the middle and the high-purity air at the end of the expansion generator are reheated with the heat storage medium pressurized by pumps I and II from heat storage tanks I and II in a high-purity air-waste heat utilization heat exchanger;

[0019] Step 3: The reheated high-purity pressurized air is used as the raw gas for cryogenic air separation, and the high-purity normal-pressure hot air is used as the regeneration gas source for the molecular sieve purification system in the cryogenic air separation equipment, thereby reducing the compression and boosting system, precooling system, and purification system required for the cryogenic air separation equipment, realizing the recycling of high-purity air in the liquefied air energy storage system and reducing the power consumption of the cryogenic air separation system.

[0020] The present invention can be used to solve the problems of high power consumption in cryogenic air separation, low electricity-to-electricity conversion efficiency of conventional liquefied air energy storage, and high-purity air venting loss in the energy release stage. When the two technologies are integrated and coupled with each other, the high-purity air in the energy release stage of the conventional liquefied air energy storage device can be efficiently and fully recovered and utilized in the cryogenic air separation system. The coupling subsystem of liquefied air power generation and energy release and cryogenic air separation greatly reduces the power consumption of the cryogenic air separation system, and the overall cycle efficiency of the liquefied air energy storage system is improved by 12% compared with the conventional system. When the two technologies operate independently, the conventional operating states of the liquefied air energy storage device and the cryogenic air separation device are maintained respectively. Without changing the main process of the conventional cryogenic air device and the liquefied air energy storage device, the mutual coordination and independent operation of the two are achieved by adding control valves and the connecting pipes between them. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the structure of the present invention. DETAILED DESCRIPTION

[0022] In order to make the technical problems, technical solutions and beneficial effects to be solved by the present invention clearer, the present invention is further described in detail below in conjunction with the accompanying drawings and specific implementation methods. It should be pointed out that for ordinary technicians in this technical field, the present invention can also be improved and modified without departing from the principle of the present invention, and these improvements and modifications also fall within the scope of protection of the claims of the present invention.

[0023] The present invention will be described in detail below in conjunction with the accompanying drawings: a device for coupling liquefied air energy storage and cryogenic air separation, which includes an air liquefaction energy storage subsystem and a liquefied air power generation and energy release and cryogenic air separation coupling subsystem, the air liquefaction energy storage subsystem includes a compressor, an interstage cooler, an aftercooler, a molecular sieve adsorber, an expansion refrigerator, a heat storage tank, a gas-liquid separator and a liquefied air storage tank, and each device is connected by valve control and pipelines; the liquefied air power generation and energy release and cryogenic air separation coupling subsystem includes a low-temperature pump, an evaporator, a multi-stage reheater, an expansion generator matching the pressure of the compressor of the cryogenic air separation equipment, a high-purity air-waste heat utilization heat exchanger, and a cold storage tank, and each device is connected by valve control and pipelines. The air liquefaction energy storage subsystem is also provided with a purification device of an aftercooler and a molecular sieve adsorber, and the purification device of the aftercooler and the molecular sieve adsorber removes carbon dioxide and water from the air compressed by compressor I, and the excess heat in the air liquefaction energy storage subsystem directly or indirectly provides heating or electricity for industry and commerce, and the The compression heat in the air liquefaction energy storage subsystem is divided into two levels and recycled into two heat storage tanks. The compression heat with a temperature higher than 100 degrees Celsius is stored in heat storage tank I, and the compression heat below 100 degrees Celsius is stored in heat storage tank II, providing a matching heat source for different forms of heat use; the excess heat in the air liquefaction energy storage subsystem is directly used in the high-purity air-waste heat utilization heat exchanger as the heat source for the extraction and final high-purity air in the expansion generator, and the gas extracted from the expansion generator is used as the pressurized heat source of the deep cold air separation subsystem. The raw gas and the final high-purity air are used as the regeneration gas source for the molecular sieve adsorber. The compressor is a multi-stage structure. A cooler is connected to the rear of each compressor. A group of aftercoolers is connected to the rear of each compressor to reduce the inlet air temperature of each compressor, thereby reducing the power consumption of the compressor. The cooler, evaporator, reheater, air liquefaction heat exchanger, and high-purity air-waste heat utilization heat exchanger are one or a combination of two or more of a plate structure, a plate-fin structure, a shell and tube structure, or a spiral structure. The heat exchange method is co-current, counter-current, or cross-current.

[0024] A method for coupling a liquefied air energy storage device with a cryogenic air separation device, the method comprising a time period when renewable energy generation is sufficient or valley power and a time period when renewable energy generation is insufficient or non-valley power, wherein during the time period when renewable energy generation is sufficient or valley power, the air liquefied energy storage subsystem and the cryogenic air separation subsystem operate independently of each other,

[0025] When renewable energy is scarce or during off-peak hours, the liquefied air power generation system and the deep-cold air separation subsystem are coupled and operated in a matching manner.

[0026] The specific usage methods during the period of sufficient renewable energy generation or off-peak electricity are as follows:

[0027] Step 1: The air in the air liquefaction energy storage subsystem first enters the compressors I2-1 to 2-n for compression through the air filter 1, and the compressor I is matched with the corresponding interstage coolers 3-1 to 3-n. The cooled air enters the aftercooler 4 for cooling and dehumidification;

[0028] Step 2: The treated air is then sent to the molecular sieve adsorber for purification, and the air from which carbon dioxide and water are further removed enters the compressors II 6-1 to 6-m for pressurization. The compressor II is matched with the corresponding interstage coolers 7-1 to 7-m. The pure air treated by the interstage cooler of the compressor II is sent to the air liquefaction heat exchanger 8 for liquefaction, and a part of the pressurized air is expanded by the expansion refrigerators 9-1 and 9-2 and then sent to the gas-liquid separators 10-1 and 10-2 for gas-liquid separation. The unliquefied air is sent to the inlet of the compressor II after the air liquefaction heat exchanger 8 recovers the cold capacity to complete the air cycle;

[0029] Step 3: The liquefied air is sent to the liquefied air storage tank 11 for storage, thereby completing the high-purity air liquefaction energy storage process; the heat generated during the compression process is stored in the heat storage tank I18-1 and the heat storage tank II18-2, and a part of the stored heat is used as the heat source required for the liquefied air energy release process, and the excess heat is directly or indirectly used for industrial and commercial heating or electricity supply;

[0030] The method of using the renewable energy in short supply or off-peak hours is as follows:

[0031] Step 1: The liquefied air stored in the air liquefaction energy storage subsystem is pressurized by the cryogenic pump 12 and sent to the evaporator 13 for preheating. The cold energy of the liquefied air is recovered and stored in the cold storage tank 14 and used as part of the cold energy of the air liquefaction process;

[0032] Step 2: The preheated high-pressure air is expanded and generated through expansion generators 16-1 to 16-k that match the pressure of the compressor of the cryogenic air separation equipment. The expansion generators match the corresponding reheaters 15-1 to 15-k. High-purity air is generated through the expansion generators and partially extracted from the expansion generators. The high-purity air extracted in the middle and the high-purity air at the end of the expansion generator are reheated with the heat storage medium pressurized by pumps I19-1 and II19-2 from the heat storage tank I18-1 and the heat storage tank II18-2 in the high-purity air-waste heat utilization heat exchanger 17;

[0033] Step 3: The reheated high-purity pressurized air is used as the raw gas for cryogenic air separation, and the high-purity normal-pressure hot air is used as the regeneration gas source for the molecular sieve purification system in the cryogenic air separation equipment, thereby reducing the compression and boosting system, precooling system, and purification system required for the cryogenic air separation equipment 20, realizing the recycling of high-purity air in the liquefied air energy storage system and reducing the power consumption of the cryogenic air separation system.

[0034] Specific implementation example: For example, during the time when renewable energy sources such as photovoltaic power generation and wind power generation are sufficient or in valley electricity, air at normal temperature and pressure first passes through an air filter 1 and is then compressed to about 8 kg by compressors I2-1 to 2-n. An interstage cooler is provided for compressor I. The heat generated during the compression process is transferred to two heat storage tanks I18-1 and II18-2 at different temperatures by matching corresponding interstage coolers 3-1 to 3-n in two stages for storage. The cooled air enters the aftercooler 4 for cooling and dehumidification. The treated air is then sent to a molecular sieve adsorber for purification. The air from which carbon dioxide and water are further removed enters compressors II6-1 to 6-m for pressurization to about 100 kg. Compressor II matches corresponding interstage coolers 7-1 to 7-m to transfer the compression heat of compressor II in two stages for storage by matching corresponding interstage coolers 7-1 to 7-m. The pure air treated by the interstage cooler of compressor II is sent to the air liquid After heat exchange, a part of the pressurized air at about 200K is extracted from the air liquefaction heat exchanger 8 and sent to the expansion refrigerator 9-2 for expansion. After the remaining pressurized air is completely heat exchanged from the air liquefaction heat exchanger 8, the temperature drops to about 115K and is sent to the expansion refrigerator 9-1 for expansion and liquefaction. The high-purity air expanded by the two types of expansion refrigerators 9-1 and 9-2 is sent to the gas-liquid separators 10-1 and 10-2 for gas-liquid separation. About 47% of the unliquefied air is sent to the air The liquefaction heat exchanger 8 recovers cold energy, and the reheated high-purity air of about 276K and about 8 kg is sent to the inlet of the compressor II to complete the air circulation, and the liquefied air is sent to the liquefied air storage tank 11 for storage, thereby completing the high-purity air liquefaction energy storage process; the heat generated during the compression process is stored in the heat storage tank I18-1 and the heat storage tank II18-2, and a part of the stored heat is used as the heat source required for the liquefied air energy release process, and the excess heat is directly or indirectly used for heating or electricity for industry and commerce.

[0035] During periods of scarcity of renewable energy or non-peak electricity demand, the liquefied air power generation and energy release system and the cryogenic air separation subsystem are coupled and matched for operation: the liquefied air stored in the air liquefaction energy storage subsystem is pressurized to about 100 kg by a cryogenic pump 12 and then sent to the evaporator 13 for preheating. The cold energy of the liquefied air is recovered and stored in the cold storage tank 14 and used as part of the cold energy in the air liquefaction process. The preheated high-pressure air is expanded and generated by expansion generators 16-1 to 16-k that match the pressure of the compressor of the cryogenic air separation equipment. The expansion generator is matched with the corresponding reheater 15-1 to 15-k. The high-purity air is generated by the expansion generator, and part of the pressurized high-purity air is extracted from the expansion generator. The high-purity air extracted in the middle The high-purity air at the final stage of the air and expansion generator is reheated with the heat storage medium pressurized by pumps I19-1 and II19-2 from heat storage tank I18-1 and heat storage tank II18-2 in the high-purity air-waste heat utilization heat exchanger 17, and the reheated high-purity pressurized air is used as the raw gas for cryogenic air separation, and the high-purity normal-pressure hot air is used as the regeneration gas source for the cryogenic air separation molecular sieve purification system, thereby reducing the compression and pressurization system, precooling system, and purification system required for the cryogenic air separation equipment 20, and the electric-to-electric conversion efficiency of the liquefied air energy storage system is increased by ~12% compared with the conventional system, thereby realizing the recycling of high-purity air in the liquefied air energy storage system and reducing the power consumption of the cryogenic air separation system.

[0036] The difference between the liquefied air power generation subsystem of the present invention and the conventional liquefied air power generation subsystem is that the expansion stage of its expansion generator matches the pressure of the air compressor and the booster of the cryogenic air separation subsystem; the cryogenic air separation device includes conventional process forms such as internal compression, external compression, and self-pressurization.

Claims

1. A device for coupling liquefied air energy storage and cryogenic air separation, comprising an air liquefaction energy storage subsystem and a liquefied air power generation and energy release and cryogenic air separation coupling subsystem, characterized in that: The air liquefaction energy storage subsystem includes a compressor, an interstage cooler, an aftercooler, a molecular sieve adsorber, an expansion refrigerator, a heat storage tank, a gas-liquid separator and a liquefied air storage tank, and each device is connected by valve control and pipelines; the liquefied air power generation and energy release and deep cold air separation coupling subsystem includes a low-temperature pump, an evaporator, a multi-stage reheater, an expansion generator that matches the pressure of the deep cold air separation equipment compressor, a high-purity air-waste heat utilization heat exchanger, and a cold storage tank, and each device is connected by valve control and pipelines; the air liquefaction energy storage subsystem is also provided with a purification device for an aftercooler and a molecular sieve adsorber, and the purification device of the aftercooler and the molecular sieve adsorber converts the air compressed by compressor I into carbon dioxide and water removal; the excess heat in the air liquefaction energy storage subsystem directly or indirectly provides heat or electricity for industry and commerce, and the compressed heat in the air liquefaction energy storage subsystem is divided into two levels and respectively recovered into two heat storage tanks, wherein the compressed heat with a temperature higher than 100 degrees Celsius is stored in heat storage tank I, and the compressed heat below 100 degrees Celsius is stored in heat storage tank II, providing a matching heat source for different forms of heat use; the excess heat in the air liquefaction energy storage subsystem is directly used in the high-purity air-waste heat utilization heat exchanger as a heat source for reheating the high-purity air extracted from the expansion generator and the final stage, wherein the gas extracted from the expansion generator is used as the pressurized feed gas for the deep cold air separation subsystem, and the final stage high-purity air is used as the regeneration gas source for the molecular sieve adsorber.

2. The device for coupling liquefied air energy storage and cryogenic air separation according to claim 1 is characterized in that: The compressor has a multi-stage structure, and a cooler is connected to the rear of each compressor. A group of aftercoolers is connected to the rear of each stage compressor to reduce the inlet air temperature of each stage compressor, thereby reducing the power consumption of the compressor.

3. The device for coupling liquefied air energy storage and cryogenic air separation according to claim 1 is characterized in that The cooler, evaporator, reheater, air liquefaction heat exchanger, and high-purity air-waste heat utilization heat exchanger are one or a combination of two or more types of plate structure, plate-fin structure, shell and tube structure, or spiral structure, and the heat exchange method is co-current, counter-current, or cross-current.

4. A method for coupling liquefied air energy storage and cryogenic air separation, the method being applied to the device for coupling liquefied air energy storage and cryogenic air separation according to any one of claims 1 to 3, characterized in that: The method includes two time periods, a time period when renewable energy generation is sufficient or during off-peak hours and a time period when renewable energy generation is insufficient or during non-off-peak hours. During the time period when renewable energy generation is sufficient or during off-peak hours, the air liquefaction energy storage subsystem and the deep-cold air separation subsystem operate independently of each other, and during the time period when renewable energy generation is insufficient or during non-off-peak hours, the liquefied air power generation and energy release system and the deep-cold air separation subsystem operate in a coupled and matched manner.

5. The method for coupling liquefied air energy storage and cryogenic air separation according to claim 4 is characterized in that: The specific method of using the renewable energy generation sufficient or valley power period is as follows: Step 1: The air in the air liquefaction energy storage subsystem first passes through the air filter (1) and enters the compressor I for compression. The compressor I is matched with a corresponding interstage cooler. The cooled air enters the aftercooler (4) for cooling and dehumidification. Step 2: The treated air is then sent to a molecular sieve adsorber for purification. The air from which carbon dioxide and water have been further removed enters compressor II for pressurization. Compressor II is matched with a corresponding interstage cooler. The pure air treated by the interstage cooler of compressor II is sent to an air liquefaction heat exchanger (8) for liquefaction. A portion of the pressurized air is expanded by an expansion refrigerator and then sent to a gas-liquid separator for gas-liquid separation. The unliquefied air is sent to the inlet of compressor II after the air liquefaction heat exchanger (8) recovers the cooling capacity to complete the air cycle. Step 3: The liquefied air is sent to the liquefied air storage tank (11) for storage, thereby completing the high-purity air liquefaction energy storage process; the heat generated during the compression process is stored in the heat storage tank I and the heat storage tank II, and a part of the stored heat is used as the heat source required for the liquefied air energy release process, and the excess heat is directly or indirectly used for industrial and commercial heating or electricity.

6. The method for coupling liquefied air energy storage and cryogenic air separation according to claim 5, characterized in that: The method of using the renewable energy in short supply or off-peak hours is as follows: Step 1: The liquefied air stored in the air liquefaction energy storage subsystem is pressurized by a cryogenic pump (12) and then sent to an evaporator (13) for preheating. The cold energy of the liquefied air is recovered and stored in a cold storage tank (14) and used as part of the cold energy in the air liquefaction process. Step 2: The preheated high-pressure air is expanded and generated by an expansion generator that matches the pressure of the compressor of the cryogenic air separation device. The expansion generator matches a corresponding reheater. High-purity air is generated by the expansion generator and partially extracted from the expansion generator. The high-purity air extracted in the middle and the high-purity air at the end of the expansion generator are reheated with the heat storage medium pressurized by pumps I (19-1) and II (19-2) from heat storage tank I (18-1) and heat storage tank II (18-2) in the high-purity air-waste heat utilization heat exchanger (17); Step 3: The reheated high-purity pressurized air is used as the raw gas for cryogenic air separation, and the high-purity atmospheric pressure hot air is used as the regeneration gas source for the molecular sieve purification system in the cryogenic air separation equipment, thereby reducing the compression and boosting system, precooling system, and purification system required for the cryogenic air separation equipment (20), realizing the recycling of high-purity air in the liquefied air energy storage system and reducing the power consumption of the cryogenic air separation system.

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