Internal compression air separation-liquid air energy storage coupling method capable of stably switching storage and release working conditions

Abstract

The invention provides an internal compression air separation-liquid air energy storage coupling method capable of stably switching storage and release working conditions, and relates to the technical field of deep cooling air separation. According to the method, a gas-state raw material for air separation rectification is continuously provided by an air separation self-compressor, and a liquid-state raw material for air separation rectification is continuously input by a liquid-state air energy storage system. Only a small part of a liquid product obtained through air separation rectification provides cold energy for an air separation system, most of cold energy of the liquid product is input into a liquid air energy storage system in a direct or indirect mode, a cold energy source is provided for air liquefaction in the energy storage process, and therefore complementary utilization of the cold energy of the air separation system and the cold energy of the liquid air energy storage system is achieved. According to the internal compression air separation system, pressurization and expansion equipment does not need to be arranged, and stable switching of storage / release working conditions of the coupling system can be achieved only by adjusting the air separation liquid product flow output flow path proportion and changing the flow path direction of the regenerator. According to the method, while large-scale and distributed energy storage is realized, the use amount of air separation equipment can be reduced, and the power consumption cost of air separation operation can be reduced.

Description

Technical Field

[0001] This invention relates to the field of cryogenic air separation technology, and in particular to an internal compression air separation-liquid air energy storage coupling method with smooth switching of storage and release conditions. Background Technology

[0002] Air separation equipment, as a high-power-consuming device, accounts for approximately 5% of China's total annual electricity consumption, exhibiting characteristics of large-scale electricity consumption. Coupled with air separation equipment and liquid air energy storage systems, air separation equipment can not only achieve distributed and large-scale energy storage on the load side of industrial equipment, but also reduce the operating electricity costs of air separation equipment by leveraging the peak-valley load switching and electricity price differences of energy storage technology, thus significantly improving the economic benefits of air separation enterprises.

[0003] However, the continuous operation requirements of air separation equipment conflict with the periodic load-changing requirements of liquid air energy storage technology. This results in core equipment in the air separation section, such as compressors, booster compressors, expanders, and heat exchangers, needing to operate under a wide range of conditions when switching between storage and release modes. In particular, booster compressors and expanders may need to be frequently started and stopped to dynamically adjust the cooling balance inside the air separation system. This conflicts with the continuous and stable operation requirements of air separation equipment, thus hindering the promotion and application of liquid air energy storage technology in the air separation industry. Summary of the Invention

[0004] To address the challenges of wide-range load variations in air separation equipment and frequent start-ups and shutdowns of some equipment during the switching between storage and release modes in existing air separation and liquid air energy storage coupling technologies, this invention provides an internal compression air separation-liquid air energy storage coupling method for smooth switching between storage and release modes. The technical solution is as follows:

[0005] A method for smoothly switching between internal compression air separation and liquid air energy storage operating conditions, wherein the method is achieved through the coordinated operation of an air separation unit and a liquefied energy storage unit, specifically including: S1, Energy storage process: The air separation unit and the liquefied energy storage unit operate synchronously. S11. The ambient air in the air separation unit is compressed, cooled, washed and dried by the air compression system, precooling system and purification system 1, and then enters heat exchanger 1. After being cooled, it provides gaseous feedstock for the air separation distillation system. S12. The ambient air in the liquefied energy storage unit is compressed, cooled and purified in sequence through the compressor, cooler one, purification system two, booster and cooler two before entering heat exchanger two. S13. The high-pressure air, after being liquefied by the heat exchanger, enters the liquid air storage tank through the expander. S14. The air output from the liquid air storage tank enters the second heat exchanger for reheating and is then recovered and enters the compressor inlet. The cryogenic liquid air output from the liquid air storage tank is pressurized by the liquid air pump and then input into the air separation unit's distillation system to provide liquid feedstock for the air separation distillation system. S15. The liquid oxygen output from the air separation and distillation system is pressurized by the liquid oxygen pump and divided into two parts: more than 90% of the liquid oxygen enters the second heat exchanger of the liquefied energy storage unit for vaporization and reheating, and the remaining liquid oxygen directly enters the first heat exchanger of the air separation unit for vaporization and reheating. S2, during the energy release process, the compressor, cooler one, purification system two, booster compressor, cooler two, expansion refrigeration unit, heat exchanger two, and expander of the liquefied energy storage unit all stop operating. The cryogenic liquid in the liquid air storage tank is boosted by the liquid air pump and sent to the air separation distillation system to participate in distillation. The air separation unit maintains the same operating state as the energy storage process, and switches the liquid oxygen product entering heat exchanger 2 from the energy storage process to the liquid oxygen evaporator, realizing the storage / release change operation of the coupled system.

[0006] In S11, the ambient air enters the air separation and distillation system after heat exchange in heat exchanger one. In the air separation and distillation system, liquid oxygen, nitrogen and waste nitrogen are separated. The nitrogen and waste nitrogen are then reheated by heat exchanger one and output from the air separation system.

[0007] After the nitrogen and waste nitrogen are output from the air separation system, the stored cold energy is extracted through a cold accumulator during the energy storage process, and then enters heat exchanger 2 to provide cold energy for the liquefaction of high-pressure air.

[0008] In S13, a portion of the high-pressure air (approximately 11%-15% by volume) in heat exchanger two is extracted from the middle of heat exchanger two and enters the expansion and refrigeration unit. The cold air output after expansion and refrigeration enters heat exchanger two for reheating, and then enters purification system two.

[0009] In S2, the liquid oxygen product is vaporized and reheated in the liquid oxygen evaporator and then output to the main oxygen pipeline. The liquid oxygen vaporization cooling energy is stored in the cold storage tank using the waste nitrogen or nitrogen output from the air separation unit as a carrier. The waste nitrogen or nitrogen from the cold storage unit is reheated and then merged into the waste nitrogen or nitrogen main pipeline output from the air separation unit.

[0010] The reheated oxygen from heat exchanger S11 and heat exchanger S12 is all fed into the main oxygen pipeline.

[0011] The air separation unit includes an air compression system, a precooling system, a purification system, a heat exchanger, a distillation system, and a liquid oxygen pump; The liquefied energy storage unit includes a compressor, a cooler I, a purification system II, a booster compressor, a cooler II, an expansion refrigeration unit, a heat exchanger II, a liquid air storage tank, a liquid air pump, a cold accumulator, a liquid oxygen evaporator, and an expander.

[0012] The air compression system, precooling system, purification system one, and heat exchanger one are connected in sequence. The air outlet of heat exchanger one is connected to the distillation system. The nitrogen and waste nitrogen outlets of the distillation system are connected to the nitrogen and waste nitrogen inlets of heat exchanger one, respectively. The oxygen outlet of the distillation system is connected to the liquid oxygen pump inlet. The liquid oxygen pump outlet is connected to the oxygen inlet of heat exchanger one, the liquid oxygen evaporator, and the oxygen inlet of heat exchanger two, respectively. The oxygen outlets of heat exchanger one, the liquid oxygen evaporator, and the heat exchanger two are all connected to the main oxygen pipeline. The nitrogen outlet of heat exchanger one is connected to the main nitrogen pipeline. The waste nitrogen outlet of heat exchanger one is connected to the precooling system, purification system one, cold storage, and liquid oxygen evaporator. The compressor, cooler one, purification system two, booster compressor, cooler two, and heat exchanger two are connected in sequence. The liquid air outlet of heat exchanger two is connected to the expander. The high-pressure air outlet of heat exchanger two is connected to the expansion refrigeration unit. The outlet of the expansion refrigeration unit is connected to heat exchanger two. The outlet of the expander is connected to the liquid air storage tank. The air outlet of the liquid air storage tank is connected to heat exchanger two. The liquid outlet of the liquid air storage tank is connected to the liquid air pump. The outlet of the liquid air pump is connected to the distillation system. Another air outlet of heat exchanger two is connected to the compressor. The third air outlet of heat exchanger two is connected to purification system two. The waste nitrogen outlet of heat exchanger two is connected to the precooling system and purification system one. The cold storage unit is connected to heat exchanger 2, heat exchanger 1 and liquid oxygen evaporator, and the waste nitrogen outlet of the cold storage unit is connected to the precooling system and purification system 1. The liquid oxygen evaporator is connected to heat exchanger one and heat exchanger two, and the oxygen outlet of the liquid oxygen evaporator is connected to the main oxygen pipeline.

[0013] Valves are installed on the pipelines connecting the liquid oxygen pump to heat exchanger two and the liquid oxygen evaporator, respectively. A valve is installed on the pipeline connecting the heat exchanger to the cold accumulator. Valves are installed on the pipeline connecting the cold accumulator and the heat exchanger. Valves are installed on the pipeline connecting the cold accumulator and the liquid oxygen evaporator; Valves are installed on the pipeline connecting the cold storage unit, precooler, and purification system.

[0014] In the above method, after gaseous and liquid air feedstocks are input into the air separation distillation system, liquid oxygen, nitrogen, and waste nitrogen are obtained through distillation. The nitrogen and waste nitrogen are output after heat exchange with the positive flow low-pressure air in S11 in the air separation heat exchange equipment. The liquid oxygen is pressurized by a cryogenic pump and divided into two parts: a small amount of liquid oxygen enters the air separation heat exchange equipment to compensate for the cooling capacity of the air separation; most of the liquid oxygen is directly input into the heat exchange equipment of the liquefaction unit during the energy storage period, and the cold energy is stored in the accumulator during the energy release period and extracted during the energy storage period for the air liquefaction process in the liquefaction unit.

[0015] Liquid oxygen cold energy storage can be achieved by exchanging heat with the waste nitrogen output from air separation distillation. That is, during the energy release period, the waste nitrogen output from air separation exchanges heat with the pressurized liquid oxygen and then stores the liquid oxygen cold energy through a cold accumulator. After that, the waste nitrogen is input into the pre-cooling or purification system of air separation. During the energy storage period, the waste nitrogen is again used to extract cold energy through the cold accumulator and then input into the heat exchange equipment of the liquefied energy storage unit. After reheating, the waste nitrogen is then input into the air separation pre-cooling or purification system.

[0016] In the above method, during the energy storage process, the flow path of liquid oxygen into the liquid oxygen evaporator is closed, while the flow path of liquid oxygen into the heat exchange equipment of the liquefaction unit and the cold energy extraction flow path of the cold accumulator are started; during the energy release process, the flow path of liquid oxygen into the heat exchange equipment of the liquefaction unit is closed, while the flow path of liquid oxygen into the liquid oxygen evaporator and the cold energy storage flow path of the cold accumulator are started. That is, the smooth switching of the air separation equipment during the storage / release process can be achieved simply by changing the liquid oxygen flow distribution ratio and switching the direction of the cold accumulator flow path.

[0017] The liquid products obtained by distillation in the above-mentioned distillation system are not limited to liquid oxygen, but can also be liquid nitrogen.

[0018] This method can also be applied to process systems that couple external compressed air separation with liquid air energy storage, as well as to all-liquid air separation processes.

[0019] The beneficial effects of the technical solutions provided in the embodiments of the present invention include at least the following: In the above scheme, the air separation unit eliminates the air pressurization and expansion equipment based on conventional internal compression air separation, reducing the high-pressure air liquefaction and expansion cooling heat exchange streams in the conventional internal compression air separation heat exchange unit. By splitting the raw material source of the air separation unit—that is, all the gaseous feedstock for distillation comes from the internal compressor of the air separation unit, and all the liquid feedstock for distillation comes from the liquefaction unit—and by providing the liquid product obtained from the air separation unit with a cold source for the air liquefaction of the liquefaction unit in both direct and indirect forms, efficient coupling between the air separation and liquid air energy storage systems can be achieved. During energy storage, the air separation unit and the liquefaction unit operate synchronously. The liquefaction unit provides liquid air feedstock to the air separation unit, and the air separation unit provides liquid product cold energy to the liquefaction unit. During energy release, the liquefaction unit stops operating, and the stored cryogenic liquid air is pressurized and continuously inputs liquid feedstock to the air separation unit. Most of the cold energy of the liquid product obtained from air separation distillation is stored and used for the air liquefaction process of the liquefaction unit during energy storage. This method not only enables high-quality complementary utilization of cold energy between the two systems and stable operation of the air separation equipment during the switching of storage and release conditions, but also simplifies the internal compression air separation process and significantly reduces the production and operating costs of the air separation equipment. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a flowchart of an internal compression air separation-liquid air energy storage coupling method for smooth switching of storage and release conditions provided in an embodiment of the present invention.

[0022] Wherein: 1-Air compression system; 2-Precooling system; 3-Purification system one; 4-Heat exchanger one; 5-Liquid oxygen pump; 6-Distillation system; 7-Compressor; 8-Cooler one; 9-Purification system two; 10-Booster; 11-Cooler two; 12-Expansion refrigeration unit; 13-Heat exchanger two; 14-Liquid air storage tank; 15-Liquid air pump; 16-Crystal accumulator; 17-Liquid oxygen evaporator; 18-Expander. Detailed Implementation

[0023] The technical solution of the present invention will now be described with reference to the accompanying drawings.

[0024] In embodiments of the present invention, words such as "exemplarily," "for example," etc., are used to indicate that something is an example, illustration, or description. Any embodiment or design described as "exemplary" in the present invention should not be construed as being more preferred or advantageous than other embodiments or designs. Specifically, the use of the word "exemplary" is intended to present the concept in a concrete manner. Furthermore, in embodiments of the present invention, the meaning expressed by "and / or" can be both, or either one.

[0025] In this embodiment of the invention, sometimes a subscript such as W1 may be written in a non-subscript form such as W1. When the difference is not emphasized, the meaning they express is the same.

[0026] To make the technical problems, technical solutions and advantages of the present invention clearer, a detailed description will be given below in conjunction with the accompanying drawings and specific embodiments.

[0027] This invention provides a method for smoothly switching between internal compression air separation and liquid air energy storage conditions. For example... Figure 1 The flowchart shown illustrates a coupling method for internal compression air separation and liquid air energy storage that allows for smooth switching between storage and release conditions. This method is achieved through the coordinated operation of the air separation unit and the liquefied energy storage unit, and specifically includes:

[0028] S1, Energy storage process: The air separation unit and the liquefied energy storage unit operate synchronously. S11. The ambient air in the air separation unit is compressed, cooled, washed and dried by the air compression system 1, the precooling system 2 and the purification system 3, and then enters the heat exchanger 4. After being cooled, it provides gaseous feedstock for the air separation distillation system 6. S12. The ambient air in the liquefied energy storage unit is compressed, cooled and purified in sequence through compressor 7, cooler 1 8, purification system 2 9, booster 10 and cooler 2 11 before entering heat exchanger 2 13. S13. The high-pressure air liquefied by heat exchanger 13 enters the liquid air storage tank 14 through expander 18. S14 The air output from the liquid air storage tank 14 enters the heat exchanger 13 for reheating and is then recovered and enters the compressor 7 inlet. The cryogenic liquid air output from the liquid air storage tank 14 is pressurized by the liquid air pump 15 and then input into the air separation unit distillation system 6 to provide liquid feedstock for the air separation distillation system. S15. The liquid oxygen output from the air separation and distillation system 6 is pressurized by the liquid oxygen pump 5 and divided into two parts: more than 90% of the liquid oxygen enters the heat exchanger 13 of the liquefied energy storage unit for vaporization and reheating, and the remaining liquid oxygen directly enters the heat exchanger 4 of the air separation unit for vaporization and reheating. S2, during the energy release process, the compressor 7, cooler 1 8, purification system 2 9, booster 10, cooler 2 11, expansion refrigeration unit 12, heat exchanger 2 13 and expander 18 of the liquefied energy storage unit all stop operating. The cryogenic liquid in the liquid air storage tank 14 is boosted by the liquid air pump 15 and sent to the air separation distillation system 6 to participate in distillation. The air separation unit maintains the same operating state as the energy storage process, and switches the liquid oxygen product entering the heat exchanger 13 of the energy storage process to the liquid oxygen evaporator 17 to realize the storage / release change operation of the coupled system.

[0029] In S11, the ambient air enters the air separation and distillation system 6 after heat exchange in the heat exchanger 4. In the distillation system 6, liquid oxygen, nitrogen and waste nitrogen are separated. The nitrogen and waste nitrogen are then reheated by the heat exchanger 4 and output to the air separation system.

[0030] The air separation unit includes an air compression system 1, a precooling system 2, a purification system 3, a heat exchanger 4, a distillation system 6, and a liquid oxygen pump 5; The liquefied energy storage unit includes a compressor 7, a cooler 8, a purification system 9, a booster 10, a cooler 11, an expansion refrigeration unit 12, a heat exchanger 13, a liquid air storage tank 14, a liquid air pump 15, a cold accumulator 16, a liquid oxygen evaporator 17, and an expander 18.

[0031] The air compression system 1, precooling system 2, purification system 3, and heat exchanger 4 are connected in sequence. The air outlet of heat exchanger 4 is connected to distillation system 6. The nitrogen and waste nitrogen outlets of distillation system 6 are connected to the nitrogen and waste nitrogen inlets of heat exchanger 4, respectively. The oxygen outlet of distillation system 6 is connected to the inlet of liquid oxygen pump 5. The outlet of liquid oxygen pump 5 is connected to the oxygen inlet of heat exchanger 4, liquid oxygen evaporator 17, and heat exchanger 13, respectively. The oxygen outlets of heat exchanger 4, liquid oxygen evaporator 17, and heat exchanger 13 are all connected to the main oxygen pipeline. The nitrogen outlet of heat exchanger 4 is connected to the main nitrogen pipeline. The waste nitrogen outlet of heat exchanger 4 is connected to precooling system 2, purification system 3, cold storage 16, and liquid oxygen evaporator 17. The compressor 7, cooler 1 8, purification system 2 9, booster 10, cooler 2 11, and heat exchanger 2 13 are connected in sequence. The liquid air outlet of heat exchanger 2 13 is connected to expander 18. The high-pressure air outlet of heat exchanger 2 13 is connected to expansion refrigeration unit 12. The outlet of expansion refrigeration unit 12 is connected to heat exchanger 2 13. The outlet of expander 18 is connected to liquid air storage tank 14. The air outlet of liquid air storage tank 14 is connected to heat exchanger 2 13. The liquid outlet of liquid air storage tank 14 is connected to liquid air pump 15. The outlet of liquid air pump 15 is connected to distillation system 6. Another air outlet of heat exchanger 2 13 is connected to compressor 7. The third air outlet of heat exchanger 2 13 is connected to purification system 2 9. The waste nitrogen outlet of heat exchanger 2 13 is connected to precooling system 2 and purification system 1 3. The cold storage 16 is connected to heat exchanger 2 13, heat exchanger 1 4 and liquid oxygen evaporator 17, and the waste nitrogen outlet of the cold storage 16 is connected to precooling system 2 and purification system 1 3. The liquid oxygen evaporator 17 is connected to heat exchanger 4 and heat exchanger 13, and the oxygen outlet of the liquid oxygen evaporator 17 is connected to the main oxygen pipeline.

[0032] Valves are respectively installed on the pipeline connecting the liquid oxygen pump 5 to the heat exchanger 2 13 and the liquid oxygen evaporator 17. A valve is provided on the pipeline connecting the heat exchanger 4 to the cold accumulator 16; Valves are installed on the pipeline connecting the cold accumulator 16 and the heat exchanger 13. Valves are installed on the pipeline connecting the cold accumulator 16 and the liquid oxygen evaporator 17; Valves are installed on the pipelines connecting the cold storage 16, the precooling system 2, and the purification system 3.

[0033] The following description, in conjunction with specific embodiments, illustrates this point.

[0034] like Figure 1 The figure shown illustrates the oxygen production of 40,000 Nm³ in an embodiment of the present invention. 3 / h Flow diagram of the integrated process of internal compression air separation and liquid air energy storage coupling with smooth switching of storage and release conditions.

[0035] During the energy storage process, the air separation unit and the liquefaction unit operate synchronously. Ambient air from the air separation unit is compressed, cooled, washed, and dried by the compression system 1, precooling system 2, and purification system 3 before entering heat exchanger 4. In heat exchanger 4, the air is cooled to approximately -173°C and then enters the air separation distillation system 6. Liquid oxygen, nitrogen, and waste nitrogen are separated in distillation system 6. The nitrogen and waste nitrogen are reheated in heat exchanger 4 and then output from the air separation system. The liquid oxygen product is pressurized by liquid oxygen pump 5 and divided into two parts: less than 10% of the liquid oxygen enters heat exchanger 4 to compensate for the cooling load in the air separation heat exchange system; the remaining liquid oxygen enters heat exchanger 13 of the liquefaction unit to provide a cooling source for the air liquefaction of the liquefaction unit. The ambient air in the liquefaction unit is compressed, cooled, and purified sequentially through compressor 7, cooler 8, purification system 9, booster compressor 10, and cooler 11 before entering heat exchanger 13. In heat exchanger 13, some of the high-pressure air is drawn from the middle and enters expansion refrigeration unit 12. The cold air output after expansion refrigeration reheats in heat exchanger 13 before entering purification system 9. The high-pressure air liquefied in heat exchanger 13 passes through expander 18 and then enters liquid air storage tank 14. The air output from liquid air storage tank 14 reheats in heat exchanger 13 before being recycled to the inlet of compressor 7. The cryogenic liquid air output from liquid air storage tank 14 is boosted by liquid air pump 15 and then input into the air separation unit's distillation system 6 to provide liquid feedstock for air separation distillation.

[0036] The waste nitrogen or nitrogen gas output from the air separation unit is used to extract and store cold energy through the cold storage unit 16, and then enters the heat exchanger 13 to provide cold energy for the liquefaction of high-pressure air.

[0037] During the energy release process, the compressor 7, cooler 1 8, purification system 2 9, booster compressor 10, cooler 2 11, expansion refrigeration unit 12, heat exchanger 2 13, and expander 18 of the liquefaction unit all stop operating. The cryogenic liquid in the liquid air storage tank 14 is pressurized by the liquid air pump 15 and sent to the air separation distillation system 6 for distillation. The air separation unit maintains the same operating state as the energy storage process. The storage / release operation of the coupled system can be achieved simply by switching the liquid oxygen product entering the heat exchanger 2 13 during the energy storage process to the liquid oxygen evaporator 17. In the liquid oxygen evaporator 17, the liquid oxygen product is vaporized and reheated before being output to the main oxygen pipeline. The cold energy from the liquid oxygen vaporization is stored in the cold accumulator 16 using the waste nitrogen or nitrogen gas output from the air separation unit as a carrier. The waste nitrogen or nitrogen gas from the cold accumulator 16 is reheated and then merged into the waste nitrogen or nitrogen gas main pipeline output from the air separation unit.

[0038] The implementation of the coupling integration method of this invention can achieve 2.75 MW / 10,000 Nm 3 The energy storage capacity of oxygen air separation production and 44 MWh / 10,000 Nm³ 3The energy storage capacity of the oxygen air separation production line has an energy storage power conversion efficiency of no less than 80%. When the peak-to-valley electricity price is 3:2:1 (valley electricity price is 0.298 yuan / kWh), the total daily electricity cost of the coupled system can be reduced by 22.6% compared to conventional internal compression air separation equipment. Therefore, this invention improves the efficiency of liquid-air energy storage, promotes cost reduction in air separation equipment operation, and also enables stable operation of time-separated air separation equipment with storage-release switching conditions.

[0039] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any variations or substitutions that can be easily conceived by those skilled in the art within the technical scope disclosed in the present invention should be included within the scope of protection of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A method for smooth switching between internal compressed air separation and liquid air energy storage, characterized in that, The method is achieved through the coordinated operation of an air separation unit and a liquefied energy storage unit, specifically including: S1, Energy storage process: The air separation unit and the liquefied energy storage unit operate synchronously. S11. The ambient air in the air separation unit is compressed, cooled, washed and dried by the air compression system, precooling system and purification system 1, and then enters heat exchanger 1. After being cooled, it provides gaseous feedstock for the air separation distillation system. S12. The ambient air in the liquefied energy storage unit is compressed, cooled and purified in sequence through the compressor, cooler one, purification system two, booster and cooler two before entering heat exchanger two. S13. The high-pressure air, after being liquefied by the heat exchanger, enters the liquid air storage tank through the expander. S14. The air output from the liquid air storage tank enters the second heat exchanger for reheating and is then recovered and enters the compressor inlet. The cryogenic liquid air output from the liquid air storage tank is pressurized by the liquid air pump and then input into the air separation unit's distillation system to provide liquid feedstock for the air separation distillation system. S15. The liquid oxygen output from the air separation and distillation system is pressurized by the liquid oxygen pump and divided into two parts: more than 90% of the liquid oxygen enters the second heat exchanger of the liquefied energy storage unit for vaporization and reheating, and the remaining liquid oxygen directly enters the first heat exchanger of the air separation unit for vaporization and reheating. S2, during the energy release process, the compressor, cooler one, purification system two, booster compressor, cooler two, expansion refrigeration unit, heat exchanger two, and expander of the liquefied energy storage unit all stop operating. The cryogenic liquid in the liquid air storage tank is boosted by the liquid air pump and sent to the air separation distillation system to participate in distillation. The air separation unit maintains the same operating state as the energy storage process, and switches the liquid oxygen product entering heat exchanger 2 from the energy storage process to the liquid oxygen evaporator, realizing the storage / release change operation of the coupled system.

2. The internal compression air separation-liquid air energy storage coupling method with smooth switching of storage and release conditions according to claim 1, characterized in that, In S11, the ambient air enters the air separation and distillation system after heat exchange in heat exchanger one. In the air separation and distillation system, liquid oxygen, nitrogen and waste nitrogen are separated. The nitrogen and waste nitrogen are then reheated by heat exchanger one and output from the air separation system.

3. The internal compression air separation-liquid air energy storage coupling method with smooth switching of storage and release conditions according to claim 2, characterized in that, During the energy storage process, after the nitrogen and waste nitrogen are output from the air separation system, the stored cold energy is extracted through the cold storage device and then enters the second heat exchanger to provide cold energy for the liquefaction of high-pressure air.

4. The internal compression air separation-liquid air energy storage coupling method with smooth switching of storage and release conditions according to claim 1, characterized in that, In S13, 11%-15% of the high-pressure air in heat exchanger two is extracted from the middle of heat exchanger two and enters the expansion and refrigeration unit. The cold air output after expansion and refrigeration enters heat exchanger two for reheating, and then enters purification system two.

5. The internal compression air separation-liquid air energy storage coupling method with smooth switching of storage and release conditions according to claim 1, characterized in that, In S2, the liquid oxygen product is vaporized and reheated in the liquid oxygen evaporator and then output to the main oxygen pipeline. The liquid oxygen vaporization cooling energy is stored in the cold storage tank using the waste nitrogen or nitrogen output from the air separation unit as a carrier. The waste nitrogen or nitrogen from the cold storage unit is reheated and then merged into the waste nitrogen or nitrogen main pipeline output from the air separation unit.

6. The internal compression air separation-liquid air energy storage coupling method with smooth switching of storage and release conditions according to claim 1, characterized in that, The reheated oxygen from heat exchanger S11 and heat exchanger S12 is all fed into the main oxygen pipeline.

7. The internal compression air separation-liquid air energy storage coupling method with smooth switching of storage and release conditions according to claim 1, characterized in that, The air separation unit includes an air compression system, a precooling system, a purification system, a heat exchanger, a distillation system, and a liquid oxygen pump; The liquefied energy storage unit includes a compressor, a cooler I, a purification system II, a booster compressor, a cooler II, an expansion refrigeration unit, a heat exchanger II, a liquid air storage tank, a liquid air pump, a cold accumulator, a liquid oxygen evaporator, and an expander.

8. The internal compression air separation-liquid air energy storage coupling method with smooth switching of storage and release conditions according to claim 7, characterized in that, The air compression system, precooling system, purification system one, and heat exchanger one are connected in sequence. The air outlet of heat exchanger one is connected to the distillation system. The nitrogen and waste nitrogen outlets of the distillation system are connected to the nitrogen and waste nitrogen inlets of heat exchanger one, respectively. The oxygen outlet of the distillation system is connected to the liquid oxygen pump inlet. The liquid oxygen pump outlet is connected to the oxygen inlet of heat exchanger one, the liquid oxygen evaporator, and the oxygen inlet of heat exchanger two, respectively. The oxygen outlets of heat exchanger one, the liquid oxygen evaporator, and the heat exchanger two are all connected to the main oxygen pipeline. The nitrogen outlet of heat exchanger one is connected to the main nitrogen pipeline. The waste nitrogen outlet of heat exchanger one is connected to the precooling system, purification system one, cold storage, and liquid oxygen evaporator. The compressor, cooler one, purification system two, booster compressor, cooler two, and heat exchanger two are connected in sequence. The liquid air outlet of heat exchanger two is connected to the expander. The high-pressure air outlet of heat exchanger two is connected to the expansion refrigeration unit. The outlet of the expansion refrigeration unit is connected to heat exchanger two. The outlet of the expander is connected to the liquid air storage tank. The air outlet of the liquid air storage tank is connected to heat exchanger two. The liquid outlet of the liquid air storage tank is connected to the liquid air pump. The outlet of the liquid air pump is connected to the distillation system. Another air outlet of heat exchanger two is connected to the compressor. The third air outlet of heat exchanger two is connected to purification system two. The waste nitrogen outlet of heat exchanger two is connected to the precooling system and purification system one. The cold storage unit is connected to heat exchanger 2, heat exchanger 1 and liquid oxygen evaporator, and the waste nitrogen outlet of the cold storage unit is connected to the precooling system and purification system 1. The liquid oxygen evaporator is connected to heat exchanger one and heat exchanger two, and the oxygen outlet of the liquid oxygen evaporator is connected to the main oxygen pipeline.

9. The internal compression air separation-liquid air energy storage coupling method with smooth switching of storage and release conditions according to claim 1, characterized in that, Valves are installed on the pipelines connecting the liquid oxygen pump to heat exchanger two and the liquid oxygen evaporator, respectively. A valve is installed on the pipeline connecting the heat exchanger to the cold accumulator. Valves are installed on the pipeline connecting the cold accumulator and the heat exchanger. Valves are installed on the pipeline connecting the cold accumulator and the liquid oxygen evaporator; Valves are installed on the pipelines connecting the cold storage unit, the precooling system, and the purification system.

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