Liquid air energy storage system

Abstract

The utility model discloses a liquid air energy storage system which comprises an air compression unit, an air purification unit, an air liquefaction storage unit, an air expansion power generation unit, a cold storage unit and a heat storage unit. The air compression unit, the air purification unit and the air liquefaction storage unit are sequentially connected through an air liquefaction circulation pipeline, compression heat energy generated in the air compression process is stored to the heat storage unit through a heat storage circulation pipeline, and cold energy of the cold storage unit is transmitted to the air liquefaction storage unit through a cold storage circulation pipeline; the air liquefaction storage unit and the air expansion power generation unit are connected through an air power generation circulation pipeline, compression heat is transmitted to the heat storage unit through a heat storage circulation pipeline, and cold energy generated in the evaporation and gasification process is transmitted to the cold storage unit through a cold storage circulation pipeline. Compared with a conventional liquid air energy storage system, the liquid air energy storage system has higher power conversion efficiency and air liquefaction efficiency through one-stage or multi-stage expansion self-pressurization circulation, and is beneficial to improving the system stability and the system power generation capacity.

Description

Technical Field

[0001] The utility model relates to the technical field of liquid air energy storage, and more specifically to a liquid air energy storage system. Background Art

[0002] Vigorously developing renewable energy is an important measure to build a new energy system. However, the high proportion of renewable energy with intermittent and unstable characteristics connected to the power grid will pose severe challenges to the safe and stable operation of the power grid. Energy storage can provide services such as peak shaving, frequency modulation, and black start, which can solve the problem of high proportion of renewable energy connected to the power grid and is considered to be a key component of the new power system. Liquid air energy storage technology based on new deep cooling technology has the characteristics of high energy storage density, green and clean, high safety, and no restrictions on geographical conditions. It is one of the new large-scale long-term energy storage technologies that can realize the grid connection and consumption of new energy, reasonably absorb valley electricity, surplus cooling, and surplus heat resources, and can stably output various forms of energy such as cold, heat, electricity, and industrial steam. Although liquid air energy storage systems have great potential in improving energy utilization efficiency and responding to energy crises, their system efficiency and stability issues still need to be effectively solved. Utility Model Content

[0003] The technical problem to be solved by the utility model is to provide a liquid air energy storage system, which increases the refrigeration capacity of the expansion end, improves the system stability and is beneficial to the air liquefaction cycle process; by recovering and efficiently utilizing evaporation gasification cold energy, compression heat energy, and dry clean air, the system efficiency is improved while saving equipment manufacturing and system operation costs.

[0004] In order to solve the above technical problems, the technical solutions adopted by the present utility model are as follows.

[0005] A liquid air energy storage system comprises an air compression unit, an air purification unit, an air liquefaction storage unit, an air expansion power generation unit, a cold storage unit and a heat storage unit for realizing the process of storing and releasing ambient air energy; the air compression unit, the air purification unit and the air liquefaction storage unit are connected in sequence through an air liquefaction circulation pipeline, and are used to realize the compression, purification and expansion and decompression of ambient air after cooling to obtain liquid air and store it; the compression heat energy generated in the air compression process is stored in the heat storage unit through the heat storage circulation pipeline, and the cold energy of the cold storage unit is transferred to the air liquefaction storage unit through the cold storage circulation pipeline; the air liquefaction storage unit and the air expansion power generation unit are connected through the air power generation circulation pipeline, and are used to pressurize the stored liquid air, evaporate and gasify it, and drive the air expansion unit to do work; the compression heat is transferred to the heat storage unit through the heat storage circulation pipeline, and the cold energy generated in the evaporation and gasification process is transferred to the cold storage unit through the cold storage circulation pipeline.

[0006] To further optimize the technical solution, the air compression unit includes a driving unit for providing power, an air compressor unit for air compression and an air cooler for cooling the exhaust gas of the air compressor unit, the output end of the driving unit is connected to the input end of the air compressor unit, and the output end of the air compressor unit is connected to the input end of the air cooler; the air compressor unit includes a raw material compressor and a circulating compressor, the raw material compressor and the circulating compressor are connected in parallel with split shafts, the driving motor is respectively fixed to the transmission shafts of the raw material compressor and the circulating compressor, and the output ends of the raw material compressor and the circulating compressor are respectively connected to the first cooler and the second cooler.

[0007] To further optimize the technical solution, the air purification unit includes a cold source heat exchanger, a first gas-liquid separator and an air purification system which are sequentially connected to the cold source output end of the first cooler, and the output end of the air purification system is connected to the input end of the circulation compressor.

[0008] To further optimize the technical solution, the air liquefaction storage unit includes an air liquefaction expansion self-pressurization cycle connected in sequence to the second cooler for air cooling, a cold box for further air cooling, depressurization and liquefaction, and a liquid air storage tank for storing liquid air; the air liquefaction expansion self-pressurization cycle includes an air supercharging end and an air expansion end, the air supercharging end includes a first supercharger and a second supercharger connected in sequence to the cold source output end of the second cooler for achieving air supercharging, and a third cooler and a fourth cooler connected to the first supercharger and the second supercharger respectively; the air expansion end includes a first low-temperature expansion machine and a second low-temperature expansion machine connected to the first supercharger and the second supercharger respectively; the cold box includes a liquefaction main heat exchanger connected to the second cooler for heat exchange with air, a second gas-liquid separator connected to the liquefaction main heat exchanger through a first throttle valve, and a subcooler connected to the second gas-liquid separator, and the subcooler is connected to the liquid air storage tank through a second throttle valve.

[0009] To further optimize the technical solution, the air expansion power generation unit includes a cryogenic pump, an evaporator, an air heater, an air expansion generator set and a generator which are sequentially connected to the liquid air storage tank.

[0010] To further optimize the technical solution, the cold storage unit includes a cold storage device connected to the liquefied main heat exchanger and the evaporator through a cold storage circulation pipeline, and a cold fluid conveying device arranged on the cold storage circulation pipeline.

[0011] To further optimize the technical solution, the heat storage unit includes a heat storage device connected to the air cooler and the air heater through a heat storage circulation pipeline, and a heat fluid transport device is provided on the heat storage circulation pipeline.

[0012] Due to the adoption of the above technical scheme, the technical progress achieved by the utility model is as follows.

[0013] The utility model provides a liquid air energy storage system, which has higher power conversion efficiency and air liquefaction efficiency than conventional liquid air energy storage systems through one-stage or multi-stage expansion self-pressurization cycles, which is beneficial to improving system stability and system power generation capacity.

[0014] When the utility model does not contain a cold storage unit, the process technology of recovering the cold energy of the evaporator is used to reliquefy the air extracted by the expander, thereby saving equipment manufacturing and system operation costs; through the recovery and utilization of heat energy, cold energy and dry and clean air, the system realizes the combined supply of cold-heat-electricity-air, effectively improving the energy utilization rate. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 This is a schematic diagram of the structure of Embodiment 1 of the present utility model;

[0016] Figure 2 This is a schematic diagram of the structure of Embodiment 2 of the present utility model;

[0017] Figure 3 This is a schematic diagram of the structure of Embodiment 3 of the present utility model;

[0018] Figure 4 This is a schematic diagram of the structure of Embodiment 4 of the present utility model;

[0019] Figure 5 This is a schematic diagram of the structure of Example 5 of the present utility model.

[0020] Wherein: 101. Raw material compressor, 102. First cooler, 103. Cold source heat exchanger, 104. First gas-liquid separator, 105. Air purification system, 106. Circulation compressor, 107. Second cooler;

[0021] 201. liquefaction main heat exchanger, 202. first low-temperature expansion machine, 203. first supercharger, 204. third cooler, 205. second supercharger, 206. fourth cooler, 207. second low-temperature expansion machine, 208. first throttle valve, 209. second gas-liquid separator, 210. subcooler, 211. second throttle valve, 212. liquid air storage tank, 213. cryogenic pump, 214. evaporator, 215. third throttle valve, 216. third gas-liquid separator, 217. third supercharger, 218. fifth cooler;

[0022] 301. first heater, 302. first power generation expander, 303. second heater, 304. second power generation expander;

[0023] 401. cold storage device, 402. first cold fluid delivery device, 403. second cold fluid delivery device;

[0024] 501. heat storage device, 502. first thermal fluid transport device, 503. second thermal fluid transport device;

[0025] A1. Air liquefaction circulation pipeline, B1. Air power generation circulation pipeline, C1. Cold storage circulation pipeline, H1. Heat storage circulation pipeline, H2, heating pipeline, L1. Cold source pipeline, M. Drive unit, G. Generator, 39. Cooling output, 40. Regeneration cycle, 41. Heating output. DETAILED DESCRIPTION

[0026] The present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0027] A liquid air energy storage system, such as Figure 1 As shown, it includes an air compression unit, an air purification unit, an air liquefaction storage unit, an air expansion power generation unit, a cold storage unit and a heat storage unit. The air compression unit, the air purification unit and the air liquefaction storage unit are connected in sequence through an air liquefaction circulation pipeline A1 to realize the compression, purification and expansion and decompression of ambient air after cooling to obtain liquid air and store it. The compression heat energy generated in the air compression process is stored in the heat storage unit through the heat storage circulation pipeline H1, and the cold energy of the cold storage unit is transferred to the air liquefaction storage unit through the cold storage circulation pipeline C1; the air liquefaction storage unit and the air expansion power generation unit are connected through an air power generation circulation pipeline B1 to pressurize the stored liquid air, evaporate and gasify it, and drive the air expansion unit to do work. The compression heat is transferred from the heat storage circulation pipeline H1 to the heat storage unit, and the cold energy generated in the evaporation and gasification process is transferred to the cold storage unit through the cold storage circulation pipeline C1.

[0028] The air compression unit includes a driving unit M, an air compressor group and an air cooler. The driving unit is used to provide power to the air compressor group, the air compressor group is used to compress air, and the air cooler is used to cool the exhaust of the air compressor group. The output end of the driving unit is connected to the input end of the air compressor group, and the output end of the air compressor group is connected to the input end of the air cooler.

[0029] The driving unit M is a driving motor or a wind turbine. When it is a driving motor, one or more of conventional power station off-peak electricity, nuclear power, wind power, solar power, hydropower or tidal power is used as the power source.

[0030] The air compressor unit comprises a raw material compressor 101 and a circulating compressor 106 , which are connected in parallel with split shafts, and the driving motors are fixedly connected to the transmission shafts of the raw material compressor 101 and the circulating compressor 106 , respectively.

[0031] The air cooler includes a first cooler 102 and a second cooler 107 , and input ends of the first cooler 102 and the second cooler 107 are connected to output ends of the raw material compressor and the circulating compressor, respectively.

[0032] The outlet pressure of the raw material compressor unit is between 0.3MPa and 2MPa; the outlet pressure of the circulating compressor unit is between 1MPa and 8MPa. When the compressor unit is set up with multiple compressors, the multiple compressors are connected in series or in parallel with split shafts. In the parallel form, each split shaft is dynamically connected to the main drive shaft; the exhaust of each compressor passes through the air cooler, and the compressor and cooler are integrated with air purification and purification equipment to remove solid matter and impurity gases in the air.

[0033] The air purification unit includes a cold source heat exchanger 103, a first gas-liquid separator 104 and an air purification system 105 which are sequentially connected to the cold source output end of the first cooler 102. The output end of the air purification system 105 is connected to the input end of the circulating compressor 106. The air purification unit is used to remove CO2, water vapor and argon in the raw air, which are impurity gases that affect the normal operation of air compression, cooling and liquefaction equipment and the output of liquid air. Among them, the cooling medium used by the cold source heat exchanger is refrigerant, water or air. The cold source heat exchanger is connected to the cooling medium through the cold source pipeline L1 to reduce the inlet temperature of the air purification unit. The air purification system 105 is a double-tower parallel or single-tower intermittent operation air purification system.

[0034] The air liquefaction storage unit includes an air liquefaction expansion self-pressurization cycle, a cold box and a liquid air storage tank 212. The air liquefaction expansion self-pressurization cycle, the cold box and the liquid air storage tank 212 are connected to the second cooler 107 in sequence. The air liquefaction expansion self-pressurization cycle is used to cool the air, the cold box is used to further cool the air, reduce the pressure and liquefy it, and the liquid air storage tank 212 is used to store compressed liquid air.

[0035] The air liquefaction expansion self-pressurization cycle includes an air pressurization end and an air expansion end, wherein the air pressurization end includes a first supercharger 203, a third cooler 204, a second supercharger 205 and a fourth cooler 206, which are sequentially connected to the cold source output end of the second cooler 107. The air expansion end includes a first low-temperature expander 202 and a second low-temperature expander 207, which are respectively connected to the first supercharger 203 and the second supercharger 205.

[0036] The cold box includes a liquefied main heat exchanger 201, a second gas-liquid separator 209 and a subcooler 210. The liquefied main heat exchanger 201 is connected to the cold source output end of the second cooler 107. The liquefied main heat exchanger 201 is also connected to the first low-temperature expansion machine 202 and the second low-temperature expansion machine 207. The second gas-liquid separator 209 is connected to the liquefied main heat exchanger 201 through the first throttle valve 208. The subcooler 210 is connected to the second gas-liquid separator 209. The subcooler 210 is connected to the liquid air storage tank 212 through the second throttle valve 211.

[0037] The liquid air storage tank 212 is a Dewar tank or a cryogenic tank, the tank pressure is 0.1-2 MPa, and the liquid air is stored under normal pressure or under pressure.

[0038] The air liquefaction expansion self-pressurization cycle is one or more stages, the number of air pressurization end stages is consistent with the number of air expansion end stages, and the same-stage air pressurization end and air expansion end are connected in a coaxial series form. When the air liquefaction self-pressurization cycle is one stage, the inlet temperature of the first low-temperature expander 202 is between -50℃ and -140℃, and the exhaust pressure is between 0.1 and 2MPa; when the air liquefaction self-pressurization cycle is two stages, the inlet temperature of the first low-temperature expansion end 202 is between 0℃ and -50℃, the inlet temperature of the second low-temperature expander 207 is between -50℃ and -140℃, and the exhaust pressure is between 0.1 and 2MPa. The temperature of the first throttle valve 208 before throttling is between -140℃ and -196℃, and the pressure after throttling is between 0.1 and 2MPa.

[0039] The air expansion power generation unit includes a cryogenic pump 213, an evaporator 214, an air heater, an air expansion generator set and a generator G which are sequentially connected to the liquid air storage tank 212. The cryogenic pump 213 is of reciprocating, centrifugal or hybrid type, and pressurizes the liquid air to 3MPa to 25MPa. The air heater includes a first heater 301 and a second heater 303. The air expansion generator set includes a first power generation expander 302 and a second power generation expander 304. The first power generation expander 302 and the second power generation expander 304 are respectively connected to the heat source output ends of the first heater 301 and the second heater 304.

[0040] The air intake temperature of the air expansion generator set is between 100°C and 500°C. When the expansion unit is multi-stage, the multiple expansion machines are in a coaxial series form or a split-axis parallel form. In the present application, the first power generation expansion machine 302 and the second power generation expansion machine 304 are in a coaxial series form, and the generator G is fixedly connected to the transmission shaft of the two-stage expansion unit.

[0041] The cold storage unit includes a cold storage device 401, which is connected to the liquefied main heat exchanger 201 and the evaporator 214 respectively through a cold storage circulation pipeline C1. A cold fluid conveying device is arranged on the cold storage circulation pipeline C1, wherein the cold fluid conveying equipment includes a first cold fluid conveying device 402 arranged on the cold storage circulation pipeline connected to the liquefied main heat exchanger 201 and a second cold fluid conveying device 403 arranged on the cold storage circulation pipeline connected to the evaporator 214.

[0042] The cold storage form of the cold storage device 401 is one or a combination of sensible heat cold storage or solid-liquid phase change cold storage. When the sensible heat cold storage medium is used, it is one or more of sealed ice balls, sand and gravel, concrete, aluminum belt discs or other metal materials; when the solid-liquid phase change cold storage medium is used, it is one or more of ammonia and its aqueous solution, salt aqueous solution, alkane, olefin substances and their compounds, alcohols and their aqueous solutions with a solid-liquid phase change temperature of 81K to 273K. The cold storage medium is stored in an insulated container, and the liquid air is directly in contact with the cold storage medium in the cold storage device 401 for heat exchange or indirect contact. The cold fluid conveying equipment is a pump, a compressor or a fan.

[0043] The heat storage unit includes a heat storage device 501, which is connected to an air cooler and an air heater through a heat storage circulation pipeline H1. A heat fluid transport device is arranged on the heat storage circulation pipeline H1, wherein the heat fluid transport device includes a first heat fluid transport device 502 arranged on the heat storage circulation pipeline connected to the air cooler and a second heat fluid transport device 503 arranged on the heat storage circulation pipeline connected to the air heater.

[0044] The heat storage device 501 stores heat in the form of sensible heat, latent heat or chemical reaction heat, or in combination thereof. The heat storage medium used is water, paraffin, biomass oil, inorganic crystalline hydrated salt, molten salt, metal and its alloy, organic fatty acid, stone, rock or concrete. The heat storage medium is stored in an insulated container. The thermal fluid transport device is a pump, a compressor or a fan.

[0045] The working process of the present application includes two processes: energy storage and energy release. The energy storage and energy release processes cannot be run at the same time. When storing energy, the air compression unit, air purification unit and air liquefaction storage unit work, the air power generation expansion unit is closed, the heat storage unit recovers and stores compression heat, and the cold storage unit releases cold energy to cool the compressed air to a low temperature. When releasing energy, the opposite is true. The air compression unit, air purification unit and air liquefaction storage unit are closed, the air power generation expansion unit works, the cold storage unit recovers and stores evaporation gasification cold energy, and the heat storage unit releases compression heat to further increase the air temperature.

[0046] The process of the energy storage stage is as follows: the drive unit drives the raw material compressor to compress a certain amount of air to 0.3MPa~2MPa, the CO2, water vapor and argon components in the raw material air are removed by the purification unit, and the air enters the circulating compressor unit to be compressed to 1MPa~8MPa, and the compression heat is recovered and stored in the heat storage device. The air at the outlet of the circulating compressor unit is divided into two streams. One stream enters the main heat exchanger after cooling through the booster end of the booster turbine expander, and then enters the gas-liquid separator after throttling through the throttle valve. The temperature before throttling is between -140℃ and -196℃, and the pressure after throttling is between 0.1 and 2MPa. The liquid air in the gas-liquid separator is cooled and stored in the liquid air storage tank; the other stream enters the expansion end of the booster turbine expander after passing through the liquefied main heat exchanger, and then mixes with the gaseous air in the gas-liquid separator and returns to the main heat exchanger to release the cold, and then returns to the inlet of the raw material compressor to mix with the ambient air and participate in the next cycle. The cold storage device provides cold energy through the liquefied main heat exchanger.

[0047] The process of the energy release stage is as follows: the low-temperature liquid air is pressurized to 3MPa~25MPa by a low-temperature pump and then enters the evaporator to be converted from liquid phase to gas phase. The cold energy of air vaporization is absorbed and stored by the cold storage device; the vaporized high-pressure air enters the power generation unit, and passes through one or more stages of air heaters and expanders in turn. The heat storage device releases heat energy to heat the air before entering each stage of expanders, driving the air expansion unit to do work; the unexpanded exhaust gas is directly output for air regeneration cycle, or outputs cold energy and moist clean air through evaporative cooling; the excess heat energy of the heat storage unit is directly used to provide heat to users or heat the expanded exhaust gas for air regeneration cycle.

[0048] Example 1

[0049] The structural diagram of this embodiment is as follows Figure 1As shown, in the energy storage stage, the ambient air passes through the raw material compressor 101 and the first cooler 102, enters the air purification unit to remove CO2, water vapor, and argon components in the raw material air, and then passes through the circulating compressor 106 and the second cooler 107. At the same time, the heat storage device 501 connects the first cooler 102 and the second cooler 107 through the heat storage circulation pipeline H1 to recover and store the compression heat generated by the raw material compressor 101 and the circulating compressor 106. The system is provided with a two-stage booster turbine expander, and the air at the outlet of the second cooler 107 is divided into two air flows, one of which enters the first low-temperature expander 202 at the expansion end of the first-stage booster turbine after heat exchange in the liquefied main heat exchanger 201. When the compressed gas expands and depressurizes, it outputs mechanical work to the coaxial first booster 203 and mixes with the gaseous air in the second gas-liquid separator 209 after the temperature is reduced; the other air flow flows through the first booster 203 at the two-stage boosting end of the two-stage booster turbine expander in sequence. After entering the liquefied main heat exchanger 201, the second supercharger 205 and the third cooler 204 and the fourth cooler 206 connected to the outlet of each stage of the supercharger enter the second liquefied main heat exchanger 201, and then divided into two air flows, one of which enters the second low-temperature expander 207 to compress the gas, expand and reduce the pressure, and output mechanical work to the coaxial second supercharger 205, and after the temperature is reduced, it is mixed with the gaseous air in the second gas-liquid separator 209; the other air flow is throttled and liquefied by the first throttle valve 208, and then enters the second gas-liquid separator 209. At the same time, the cold storage device 401 is connected to the liquefied main heat exchanger 201 through the cold storage circulation pipeline C1 to cool the air. The gaseous air in the second gas-liquid separator 209 is mixed with the outlet air of the first low-temperature expander 202 and the second low-temperature expander 207, and then heat-exchanged in the liquefied main heat exchanger 201, and then returned to the outlet of the air purification system 105 through the air liquefaction circulation pipeline A1 to participate in the next cycle. The liquid air in the second gas-liquid separator 209 is divided into two streams after passing through the cooler 210 and the second throttle valve 211, one of which enters the liquid air storage tank 212 for storage; the other stream passes through the cooler 210 and the liquefaction main heat exchanger 201 in turn and returns to the inlet of the raw material compressor 101 through the air liquefaction circulation pipeline A1 to mix with the ambient air and participate in the next circulation.

[0050] In the energy release stage, the low-temperature liquid air output by the liquid air storage tank 212 is pressurized to high pressure by the cryogenic pump 213 and then enters the evaporator 214 to be converted from liquid phase to gas phase. At the same time, the cold storage device 401 is connected to the evaporator 214 through the cold storage circulation pipeline C1 to recover and store the cold released during the evaporation and gasification of the high-pressure liquid air. The vaporized high-pressure air enters the air expansion power generation unit, and passes through the first heater 301, the first power generation expander 302, the second heater 303 and the second power generation expander 304 in sequence. And the heat storage device 501 is connected to the first heater 301 and the second heater 303 through the heat storage circulation pipeline H1 to heat the air before entering the first power generation expander 302 and the second power generation expander 304, and drives the air expansion unit to do work. The outlet of the second power generation expander 304 is connected to the cooling and clean air pipeline, and the expanded exhaust gas is directly output through the heating pipeline H2 for air regeneration cycle 40, or cold energy and moist clean air are output for cooling output 39 through evaporative cooling; the outlet of the second thermal fluid transport device 503 is connected to the heating pipeline H2, and the thermal energy of the heat storage unit is directly output for user heating 41 or heated expanded exhaust gas for air regeneration cycle 40.

[0051] Example 2

[0052] This embodiment is a variation of the first embodiment, which uses the reliquefaction technology to recover the cold energy of liquid air vaporization. It does not contain a cold storage unit, but adds a reliquefaction unit. A stream of compressed air is introduced at the outlet of the expander of the expansion power generation unit to recover the cold energy of the evaporator. The structural diagram is shown in FIG. Figure 2 shown.

[0053] The reliquefaction unit includes a third throttle valve 215 and a third gas-liquid separator 216. The third gas-liquid separator 216 is connected to the evaporator 214 and the input end of the liquid air storage tank 212 through the cold storage circulation pipeline C1. The third throttle valve 215 is arranged on the gas pipeline between the evaporator 214 and the third gas-liquid separator 216.

[0054] In the energy storage stage, the cold energy of the liquefied main heat exchanger 201 is only provided by the first low-temperature expander 202, the second low-temperature expander 207 and the second gas-liquid separator 209 in reverse flow.

[0055] During the energy release stage, the outlet air from the first power expansion machine 302 in the air expansion power generation unit is divided into two air flows. One air flow passes through the evaporator 214 to recover the cold released during the evaporation and gasification of the high-pressure liquid air, and after being depressurized and liquefied by the third throttle valve 215, it enters the third gas-liquid separator 214 for cold energy supply. The unliquefied air is discharged through the cold storage circulation pipeline C1 after heat exchange in the evaporator 214; the other air flow enters the second heater 303 to participate in the subsequent expansion and power generation process, thereby achieving the purpose of system simplification, cost reduction and efficiency improvement.

[0056] Example 3

[0057] The main structure of this embodiment is the same as that of embodiment 1, except that the first stage of air liquefaction expansion self-pressurization cycle is reduced, and only one stage is retained. The second supercharger 205, the fourth cooler 206 and the second low-temperature expander 207 in embodiment 1 are removed. The structural diagram is shown in FIG. Figure 3 The air liquefaction expansion self-pressurization cycle includes a first low-temperature expander 202 , a first supercharger 203 and a third cooler 204 .

[0058] During the energy storage stage, the air at the outlet of the second cooler 107 is divided into two air flows, one of which enters the expansion end of the first low-temperature expander 202 after heat exchange through the liquefied main heat exchanger 201, and outputs mechanical work to the coaxial first booster 203 when the compressed gas expands and reduces the pressure, and after the temperature is reduced, it mixes with the gaseous air in the second gas-liquid separator 209; the other air flow passes through the first booster 203 and the third cooler 204 in sequence and enters the liquefied main heat exchanger 201, and then enters the second gas-liquid separator 209 after reducing the pressure and liquefying through the first throttle valve 208. At the same time, the cold storage device 401 is connected to the liquefied main heat exchanger 201 through the cold storage circulation pipeline C1 to cool the air, thereby simplifying the system.

[0059] The process of the energy release stage in this embodiment is the same as that in the energy release stage in Embodiment 1, and will not be described in detail here.

[0060] Example 4

[0061] The main structure of this embodiment is the same as that of embodiment 1, and an additional air compression unit is added, whose structure is as follows: Figure 4 The newly added air compression unit includes a third booster 217 and a fifth cooler 218 arranged on the air liquefaction circulation pipeline after passing through the subcooler 210 and the liquefaction main heat exchanger 201, and the output end of the fifth cooler 218 is connected to the output end of the air purification system 105.

[0062] During the energy storage stage, the liquid air in the second gas-liquid separator 209 is divided into two air flows after passing through the cooler 210 and the second throttle valve 211, one of which enters the liquid air storage tank 212 for storage; the other air flow passes through the subcooler 210 and the liquefied main heat exchanger 201 in turn, and is pressurized and cooled by the added third compressor 217 and the fifth cooler 218. The gaseous air in the second gas-liquid separator 209 is mixed with the air at the outlets of the first low-temperature expander 202 and the second low-temperature expander 207, and then mixed with the air liquefied circulation pipeline A1 after heat exchange in the liquefied main heat exchanger 201 and the gas pipeline coming out of the fifth cooler, and then returns to the outlet of the air purification system 105 after mixing to participate in the next cycle, thereby reducing the air purification cost.

[0063] The process of the energy release stage in this embodiment is the same as that in the energy release stage in Embodiment 1, and will not be described in detail here.

[0064] Example 5

[0065] The main structure of this embodiment is deformed to a certain extent compared with embodiments 1-3. Only a first-stage expansion and self-pressurization cycle is retained. Only the first low-temperature expander 202, the first supercharger 203 and the third cooler 204 are retained. At the same time, the airflow in and out of the supercharging end and the expansion end is changed from two airflows at the outlet of the second cooler 107 to the same airflow at the outlet of the second cooler 107.

[0066] During the energy storage stage, the air at the outlet of the second cooler 107 is divided into two air flows, one of which passes through the first supercharger 203 and the third cooler 204 at the supercharging end of the supercharged turbine expander in turn and then enters the liquefied main heat exchanger 201, and then enters the first low-temperature expander 202 at the expansion end of the turbine expander, and while the compressed gas expands and reduces the pressure, it outputs mechanical work to the coaxial first supercharger 203 and enters the second gas-liquid separator 209 after the temperature is reduced; the other air flow directly enters the liquefied main heat exchanger 201 and is throttled and liquefied by the first throttle valve 208, and then enters the second gas-liquid separator 209; at the same time, the cold storage device 401 is connected to the liquefied main heat exchanger 201 through the cold storage circulation pipeline C1 to cool the air, so that the same air flow passes through the supercharger and expander, the equipment is axially balanced, and the stability is guaranteed.

[0067] The process of the energy release stage in this embodiment is the same as that in the energy release stage in Embodiment 1, and will not be described in detail here.

Claims

1. A liquid air energy storage system, characterized in that: The invention comprises an air compression unit, an air purification unit, an air liquefaction storage unit, an air expansion power generation unit, a cold storage unit and a heat storage unit for realizing the process of storing and releasing ambient air energy; the air compression unit, the air purification unit and the air liquefaction storage unit are connected in sequence through an air liquefaction circulation pipeline (A1) for realizing the compression, purification and expansion and decompression of ambient air after cooling to obtain liquid air and store it; the compression heat energy generated in the air compression process is stored in the heat storage unit through a heat storage circulation pipeline (H1); the cold energy of the cold storage unit is transferred to the air liquefaction storage unit through a cold storage circulation pipeline (C1); the air liquefaction storage unit and the air expansion power generation unit are connected through an air power generation circulation pipeline (B1) for pressurizing the stored liquid air, evaporating and gasifying it and driving the air expansion unit to do work; the compression heat is transferred to the heat storage unit through the heat storage circulation pipeline (H1); the cold energy generated in the evaporation and gasification process is transferred to the cold storage unit through the cold storage circulation pipeline (C1).

2. A liquid air energy storage system according to claim 1, characterized in that: The air compression unit comprises a driving unit (M) for providing power, an air compressor unit for air compression, and an air cooler for cooling exhaust gas of the air compressor unit, wherein the output end of the driving unit is connected to the input end of the air compressor unit, and the output end of the air compressor unit is connected to the input end of the air cooler; the air compressor unit comprises a raw material compressor (101) and a circulating compressor (106), wherein the raw material compressor and the circulating compressor are connected in parallel with split shafts, the driving motor is respectively fixedly connected to the transmission shafts of the raw material compressor (101) and the circulating compressor (106), and the output ends of the raw material compressor (101) and the circulating compressor (106) are respectively connected to a first cooler (102) and a second cooler (107).

3. A liquid air energy storage system according to claim 2, characterized in that: The air purification unit comprises a cold source heat exchanger (103) connected in sequence to the cold source output end of the first cooler (102), a first gas-liquid separator (104) and an air purification system (105), wherein the output end of the air purification system (105) is connected to the input end of the circulation compressor (106).

4. A liquid air energy storage system according to claim 2, characterized in that: The air liquefaction storage unit comprises an air liquefaction expansion self-pressurization cycle for air cooling and a cold box for further air cooling, depressurization and liquefaction, and a liquid air storage tank (212) for storing liquid air, which are sequentially connected to the second cooler (107); The air liquefaction expansion self-pressurization cycle comprises an air pressurization end and an air expansion end, wherein the air pressurization end comprises a first supercharger (203) and a second supercharger (205) connected in sequence to a cold source output end of a second cooler (107) for achieving air pressurization, and a third cooler (204) and a fourth cooler (206) connected to the first supercharger (203) and the second supercharger (205) respectively; the air expansion end comprises a first low-temperature expander (202) and a second low-temperature expander (207) connected to the first supercharger (203) and the second supercharger (205) respectively; The cold box comprises a liquefaction main heat exchanger (201) connected to a second cooler (107) for exchanging heat with air, a second gas-liquid separator (209) connected to the liquefaction main heat exchanger via a first throttle valve (208), and a subcooler (210) connected to the second gas-liquid separator, wherein the subcooler (210) is connected to a liquid air storage tank (212) via a second throttle valve (211).

5. A liquid air energy storage system according to claim 4, characterized in that: The air expansion power generation unit comprises a cryogenic pump (213), an evaporator (214), an air heater, an air expansion power generation unit and a generator (G) which are sequentially connected to a liquid air storage tank (212).

6. A liquid air energy storage system according to claim 5, characterized in that: The cold storage unit comprises a cold storage device (401) connected to a liquefaction main heat exchanger (201) and an evaporator (214) respectively through a cold storage circulation pipeline (C1), and cold fluid conveying equipment arranged on the cold storage circulation pipeline (C1).

7. A liquid air energy storage system according to claim 5, characterized in that: The heat storage unit comprises a heat storage device (501) connected to an air cooler and an air heater respectively through a heat storage circulation pipeline (H1), and a heat fluid transport device is arranged on the heat storage circulation pipeline (H1).

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