Liquid air energy storage and LNG (Liquefied Natural Gas) cold energy complementary system

Abstract

The invention belongs to the technical field of liquid air energy storage systems and LNG cold energy utilization, and discloses a liquid air energy storage and LNG cold energy complementary system which comprises a compressor unit subsystem, a heat storage subsystem, a liquid gasification subsystem, a liquid air storage tank subsystem, a cold storage subsystem and an expansion power generation subsystem. The compressor unit subsystem comprises an air filter, a normal-temperature compressor, a heat exchanger, a molecular sieve purifier, a low-temperature heat exchanger, a low-temperature compressor and a pipeline valve and is used for compressing air. The invention provides a liquid air energy storage system and method coupled with LNG cold energy complementary utilization. High-grade cold energy complementary utilization between the liquid air energy storage system and LNG is achieved. The LNG cold energy is utilized to the maximum extent, meanwhile, high-grade cold energy generated in the energy release stage can be reversely provided for BOG of the LNG receiving station, liquefaction of the BOG is achieved, waste of the BOG of the LNG receiving station and energy consumption of a BOG compressor are reduced, and complementary utilization of the cold energy is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid air energy storage system and LNG cold energy utilization, and more specifically, to a system for complementary liquid air energy storage and LNG cold energy. Background Art

[0002] With the rapid development of renewable energy in my country, renewable energy represented by wind power and photovoltaic power is promoting the green and low-carbon transformation of my country's energy structure and realizing the "dual carbon" strategy. At the same time, due to its inherent volatility, intermittency and randomness, it has brought great impact and challenges to the safe and stable operation of the power grid system. Due to the time and space mismatch of new energy power supply and demand, the power grid system urgently needs a large-scale long-term energy storage system to smooth the peak and fill the valley, so as to achieve the balance of power supply and demand while fully absorbing new energy and reducing power supply costs, improve the flexible adjustment ability of the power system, and support the construction of a new power system.

[0003] Liquid air energy storage technology is one of the important large-scale long-term energy storage technologies. It is derived from compressed air energy storage technology, but does not require the construction of underground gas storage, and is free from geological restrictions, greatly improving the flexibility, controllability, and safety of system construction. However, due to the harsh conditions of the air liquefaction process, a large amount of electricity is required to generate cold, which greatly limits the system conversion efficiency of the liquid air energy storage system.

[0004] Liquefied natural gas (LNG) is a liquid form of natural gas, which is stored in a low-temperature liquid form. It contains a large amount of high-grade cold energy, but most of the cold energy cannot be effectively recycled and is wasted. At the same time, LNG will produce a certain amount of BOG during daily storage and unloading. For large LNG receiving stations, BOG compressors are generally used to re-liquefy some of the BOG through the re-condensation process as much as possible, but some BOG cannot be recovered in time and is emptied and burned, resulting in energy waste. In addition, the compression and condensation process of BOG will also increase the compression energy consumption.

[0005] The liquid air energy storage system requires high-quality cold energy to liquefy air during the energy storage stage, and vaporizes and releases a large amount of high-quality cold energy during the energy release stage. Coupling the liquid air energy storage system with LNG to achieve efficient utilization of cold energy is an effective way to combine the advantages of LNG cold energy utilization and liquid air energy storage.

[0006] At present, the coupling modes of liquid air energy storage system and LNG cold energy only consider the utilization of LNG cold energy in the energy storage stage of the energy storage system to realize air liquefaction, but lack the application of cold energy complementarity between the liquid air energy storage system and the LNG receiving station. That is, the liquid air energy storage will provide the high-grade cold energy generated in the energy release and gasification stage back to the LNG receiving station to provide services for the liquefaction of BOG, so as to reduce the energy consumption of the BOG processing process of the LNG receiving station and the waste of BOG emission and combustion.

[0007] At the same time, the current method of utilizing liquid air energy storage coupled with LNG cold energy is either only used for the liquefaction link of the liquefaction cold box, without reducing the energy consumption of the compression link as much as possible; or the LNG cold energy is utilized by reverse heat exchange from the liquefaction cold box to the intercoolers of each section of the compressor in a cascade manner to utilize the LNG cold energy most efficiently. However, in this method, on the one hand, there is a time difference in the reverse flow of air and natural gas, the air is transported from the compressor inlet to the liquefaction cold box, and the natural gas cold energy is transported from the liquefaction cold box to the front end of the compressor. This will cause the air cooling liquefaction process and the LNG heating process to be in a dynamically changing non-steady-state process every time the system is started, and the system compression energy storage is also in a variable operating condition process. Although the system will gradually converge and reach the design operating condition, this process brings great uncertainty and impact to the system performance and LNG gasification demand. Summary of the invention

[0008] The purpose of the present invention is to solve the shortcomings of the prior art and to propose a system that complements liquid air energy storage with LNG cold energy.

[0009] To solve the above problems, the present invention adopts the following technical solutions: A system for complementary liquid air energy storage and LNG cold energy, comprising: a compressor unit subsystem, a heat storage subsystem, a liquefaction gasification subsystem, a liquid air storage tank subsystem, a cold storage subsystem and an expansion power generation subsystem; The compressor unit subsystem includes an air filter, a normal temperature compressor, a heat exchanger, a molecular sieve purifier, a low temperature heat exchanger, a low temperature compressor and pipeline valves, which are used to compress the air; The thermal storage subsystem includes a cold storage tank, a hot storage tank and a water pump, which are used to store and circulate thermal media; The liquefaction and gasification subsystem includes a liquefaction cold box, a liquid expander, a throttle valve, a gas-liquid separator, an evaporator, a BOG condenser, a BOG buffer tank, a BOG control valve and an LNG buffer tank, which are used to realize the liquefaction and gasification of air and the recondensation and liquefaction of BOG; The liquid air storage tank subsystem includes a liquid air storage tank and a cryogenic liquid pump, which are used to store and pump liquid air; The cold storage subsystem includes a cold storage device and a driving device, valves and pipelines, which are used to store and release cold energy; The expansion power generation subsystem includes a reheater, a preheater and an expansion power generation unit, which is used to utilize high-temperature pressurized air to drive the expander to expand and perform work, thereby driving the generator to generate electricity.

[0010] As a further solution of the present invention: the outlet end of the air filter is connected to the inlet end of the normal temperature compressor, the outlet end of the normal temperature compressor is connected to the inlet end of the air medium stream of the heat exchanger, the outlet of the heat exchanger is connected to the inlet end of the molecular sieve purifier, the inlet end of the heat medium stream of the heat exchanger is connected to the cold storage tank of the heat storage subsystem, and the outlet end of the heat medium stream of the interstage heat exchanger is connected to the hot storage tank of the heat storage subsystem; The air medium stream outlet end of the low-temperature heat exchanger is connected to the inlet of the low-temperature compressor, the low-temperature medium stream inlet end of the low-temperature heat exchanger is connected to the LNG pipeline on the high-pressure side of the LNG station, and the low-temperature medium stream outlet end of the low-temperature heat exchanger is connected to the NG pipeline of the LNG station.

[0011] As a further solution of the present invention: the water pump includes a cold water pump and a hot water pump, the cold storage tank is used to store the heat medium before heat storage or after cooling, the inlet end of the cold storage tank is connected to the outlet of the heat medium flow stream of the reheater of the expansion power generation subsystem, and the outlet of the cold storage tank is connected to the cold water pump; the cold water pump is connected to the inlet end of the heat medium flow stream of the heat exchanger of the compressor unit subsystem; The heat storage tank is used to store the heat medium after heat storage, the outlet end of the heat storage tank is connected to the hot water pump, the inlet end of the heat storage tank is connected to the heat exchanger heat medium flow outlet of the compressor unit subsystem, and the hot water pump is connected to the reheater heat medium flow inlet end of the expansion power generation subsystem.

[0012] As a further solution of the present invention: the air stream inlet end of the hot side of the liquefied cold box is connected to the outlet of the last section of the compressor unit subsystem, the air stream outlet end of the hot side of the liquefied cold box is connected to the liquid expander, the LNG stream inlet end of the cold side of the liquefied cold box is connected to the LNG pipeline on the high-pressure side of the LNG station, and the LNG stream outlet end of the cold side of the liquefied cold box is connected to the NG pipeline of the LNG station; the cold side cold storage device stream inlet end of the liquefied cold box is connected to the cold release outlet end of the cold storage subsystem, and the cold side cold storage device stream outlet end of the liquefied cold box is connected to the cold release inlet end of the cold storage subsystem; the cold side return air stream inlet end of the liquefied cold box is connected to the BOG condenser air stream outlet, and the cold side air stream outlet end of the liquefied cold box is connected to the inlet of the low-temperature compressor; The liquid expander is connected to the liquefied cold box and the throttle valve; The gas-liquid separator inlet is connected to the throttle valve outlet, the gas-liquid separator liquid air outlet is connected to the liquid air storage tank subsystem, and the gaseous air outlet of the gas-liquid separator is connected to the cold side air stream inlet of the BOG condenser; The BOG condenser is used to realize the recondensation and liquefaction of BOG at the LNG receiving station. The cold side outlet of the BOG condenser is connected to the cold side return air stream inlet end of the liquefaction cold box, the hot side inlet of the BOG condenser is connected to the outlet of the BOG control valve, and the hot side outlet of the BOG condenser is connected to the LNG buffer tank; The air stream inlet end of the cold side of the evaporator is connected to the outlet of the low-temperature liquid pump of the liquid-to-air storage tank system, the air stream outlet end of the cold side of the evaporator is connected to the air stream inlet end of the reheater of the expansion generator subsystem, the cold storage stream inlet end of the hot side of the evaporator is connected to the cold storage outlet end of the cold storage subsystem, the cold storage stream outlet end of the hot side of the evaporator is connected to the cold storage inlet end of the cold storage subsystem, the BOG stream inlet end of the hot side of the evaporator is connected to the outlet of the BOG control valve, and the hot side outlet of the evaporator is connected to the LNG cache tank.

[0013] As a further solution of the present invention: the inlet of the liquid air storage tank is connected to the liquid outlet end of the gas-liquid separator, the outlet of the liquid air storage tank is connected to the cryogenic liquid pump, and the outlet end of the cryogenic liquid pump is connected to the evaporator.

[0014] As a further solution of the present invention: the reheater air stream inlet end is connected to the evaporator air stream outlet or the preheater outlet, and the reheater outlet end is connected to the expansion generator set inlet; the reheater heat medium stream inlet end is connected to the heat storage subsystem hot storage tank and the hot water pump, and the reheater heat medium stream outlet end is connected to the heat storage subsystem cold storage tank; The inlet end of the preheater air stream is connected to the outlet of the expansion generator set, and the outlet end of the preheater air stream is connected to the inlet end of the reheater air stream.

[0015] Compared with the prior art, the advantages of the present invention are: The present invention provides a liquid air energy storage system and method coupled with complementary utilization of LNG cold energy, realizing complementary utilization of high-quality cold energy between the liquid air energy storage system and LNG. While maximizing the utilization of LNG cold energy, the high-quality cold energy generated in the energy release stage can be reversely provided to the BOG of the LNG receiving station to realize the liquefaction of BOG, reduce the waste of BOG at the LNG receiving station and the energy consumption of the BOG compressor, and realize complementary utilization of cold energy.

[0016] At the same time, by optimizing the system process flow, the energy consumption in the compression stage is reduced, and the non-steady-state variable operating condition process caused by the time difference of the reverse transmission of cold and hot streams is avoided, so as to meet the design conditions of the liquid air energy storage system and LNG gasification project and ensure the stability of system operation. Other waste heat and waste heat can also be used to greatly improve the system efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] Figure 1 It is a system diagram of the present invention.

[0018] Description of the numbers in the figure: 1. Air filter; 2. Normal temperature compressor; 3. Heat exchanger; 4. Molecular sieve purifier; 5. Cryogenic heat exchanger; 6. Cryogenic compressor; 7. Liquefaction cold box; 8. Liquid expander; 9. Throttle valve; 10. Gas-liquid separator; 11. Cold storage device; 12. Liquid-air storage tank; 13. Cryogenic liquid pump; 14. Evaporator; 15. Reheater; 16. Preheater; 17. Expansion generator set; 18. Cold storage tank; 19. Hot storage tank; 20. Water pump; 21. BOG condenser; 22. BOG buffer tank; 23. BOG control valve; 24. LNG buffer tank. DETAILED DESCRIPTION

[0019] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention; it is obvious that the described embodiments are only part of the embodiments of the present invention, rather than all the embodiments, and all other embodiments obtained by ordinary technicians in this field based on the embodiments of the present invention without making creative work are within the scope of protection of the present invention.

[0020] See also Figure 1 , a system that complements liquid air energy storage and LNG cold energy, including: a compressor unit subsystem, a heat storage subsystem, a liquefaction and gasification subsystem, a liquid air storage tank subsystem, a cold storage subsystem and an expansion and power generation subsystem.

[0021] The compressor unit subsystem includes an air filter 1, a normal temperature compressor 2, a heat exchanger 3, a molecular sieve purifier 4, a low temperature heat exchanger 5, a low temperature compressor 6 and pipeline valves, which are used to compress the air.

[0022] The outlet of the air filter 1 is connected to the inlet of the normal temperature compressor 2, to filter the ambient air particles. The outlet of the normal temperature compressor 2 is connected to the inlet of the air medium stream of the heat exchanger 3 to compress the air. The outlet of the heat exchanger 3 is connected to the inlet of the molecular sieve purifier 4, the inlet of the heat medium stream of the heat exchanger 3 is connected to the cold storage tank 18 of the heat storage subsystem, and the outlet of the heat medium stream of the interstage heat exchanger 3 is connected to the hot storage tank 19 of the heat storage subsystem.

[0023] Furthermore, the normal temperature compressor 2 can adopt a multi-stage compression mode, and the spaces and outlets of each stage of the normal temperature compressor are connected to the heat exchanger 3. The heat exchanger 3 and the heat exchange and heat storage medium are used to realize heat exchange cooling with the high-temperature and high-pressure air compressed by each stage of the compressor, so that the air entering the molecular sieve purifier 4 and the inlet of the next stage of the compressor is reduced to normal temperature.

[0024] The molecular sieve purifier 4 realizes adsorption and filtration of water, CO2 and hydrocarbon substances, and its outlet end is connected to the air medium stream inlet end of the low-temperature heat exchanger 5.

[0025] The air medium stream outlet of the cryogenic heat exchanger 5 is connected to the inlet of the cryogenic compressor 6, the cryogenic medium (LNG) stream inlet is connected to the LNG pipeline on the high pressure side of the LNG station, and the cryogenic medium (LNG) stream outlet is connected to the NG pipeline of the LNG station. The exchange of normal temperature air and LNG cold energy working medium is achieved through the cryogenic heat exchanger 5, which greatly reduces the compressor inlet temperature, thereby greatly reducing the compressor power consumption.

[0026] The low-temperature compressor 6 can adopt a multi-stage compression mode, each stage of the low-temperature compressor 6 is connected to a low-temperature heat exchanger 5, and the outlet of the last stage of the low-temperature compressor 6 is connected to the liquefaction cold box 7.

[0027] Furthermore, the low-temperature heat exchanger 5 and the low-temperature compressor 6 are both effectively insulated or placed in a cold box and filled with pearl sand for insulation.

[0028] The heat storage subsystem includes a cold storage tank 18, a hot storage tank 19 and a water pump 20, which are used to store and circulate heat medium. The water pump 20 includes a cold water pump and a hot water pump. The cold storage tank 18 is used to store heat medium before or after heat storage. Its inlet end is connected to the outlet of the heat medium flow stream of the reheater 15 of the expansion power generation subsystem, and its outlet is connected to the cold water pump; the cold water pump is connected to the inlet end of the heat medium flow stream of the heat exchanger 3 of the compressor unit subsystem.

[0029] The heat storage tank 19 is used to store the heat medium after heat storage, and its outlet end is connected to the hot water pump, and its inlet end is connected to the heat medium flow outlet of the heat exchanger 3 of the compressor unit subsystem, and the hot water pump is connected to the heat medium flow inlet end of the reheater 15 of the expansion power generation subsystem.

[0030] Furthermore, the heat storage medium of the heat storage subsystem may be pressurized water, thermal oil, molten salt or other fluid media.

[0031] The liquefaction and gasification subsystem includes a liquefaction cold box 7, a liquid expander 8, a throttle valve 9, a gas-liquid separator 10, an evaporator 14, a BOG condenser 21, a BOG buffer tank 22, a BOG control valve 23 and an LNG buffer tank 24, which are used to realize the liquefaction and gasification of air and the recondensation and liquefaction of BOG.

[0032] The liquefied cold box 7 adopts a multi-stream design. The air stream inlet end of the hot side of the liquefied cold box 7 is connected to the outlet of the last section of the compressor unit subsystem, the air stream outlet end of the hot side of the liquefied cold box 7 is connected to the liquid expander 8, the LNG stream inlet end of the cold side of the liquefied cold box 7 is connected to the LNG pipeline on the high-pressure side of the LNG station, and the LNG stream outlet end of the cold side of the liquefied cold box 7 is connected to the NG pipeline of the LNG station.

[0033] The cold side cold storage stream inlet end of the liquefied cold box 7 is connected to the cold storage subsystem cold release outlet end, and the refluxed unliquefied air provides a portion of the high-grade cold energy required for air liquefaction to the liquefied cold box 7. The cold side cold storage stream outlet end of the liquefied cold box 7 is connected to the cold storage subsystem cold release inlet end; the cold side return air stream inlet end of the liquefied cold box 7 is connected to the BOG condenser 21 air stream outlet end, and the cold side air stream outlet end of the liquefied cold box 7 is connected to the inlet of the low-temperature compressor 6, and enters the compressor inlet for recirculation.

[0034] Furthermore, the liquefied cold box 7 includes a low-temperature heat exchanger, a heat-insulating box body and corresponding passages. The low-temperature heat exchanger and the corresponding low-temperature passages are placed inside the cold box body and filled with pearl sand for insulation.

[0035] The liquid expander 8 is connected to the liquefied cold box 7 and the throttle valve 9, and the high-pressure and low-temperature liquid air liquefied by the liquefied cold box 7 is depressurized to the pressure required for storage in the liquid air storage tank 12 through the liquid expander 8 and the throttle valve 9. In some possible embodiments, the liquid expander 8 can be selected to output as a full liquid expander, or it can continue to reduce pressure and temperature through the throttle valve 9 or use a gas-liquid mixed liquid expander with a large liquid volume.

[0036] The gas-liquid separator 10 realizes the separation of gas-liquid two-phase air, the inlet of the gas-liquid separator 10 is connected to the outlet end of the throttle valve 9, the liquid air outlet end of the gas-liquid separator 10 is connected to the liquid air storage tank subsystem, and the gaseous air outlet end of the gas-liquid separator 10 is connected to the cold side air stream inlet end of the BOG condenser 21.

[0037] The BOG condenser 21 is used to realize the recondensation and liquefaction of BOG at the LNG receiving station. The cold side outlet of the BOG condenser 21 is connected to the cold side reflux air flow inlet end of the liquefaction cold box 7, the hot side inlet of the BOG condenser 21 is connected to the outlet of the BOG control valve 23, and the hot side outlet of the BOG condenser 21 is connected to the LNG buffer tank 24.

[0038] The evaporator 14 is used to realize the heating and gasification of liquid air and the recondensation and liquefaction of BOG in the energy release stage, and adopts a multi-stream design. The cold side air stream inlet end of the evaporator 14 is connected to the outlet of the cryogenic liquid pump 13 of the liquid air storage tank system, the cold side air stream outlet end of the evaporator 14 is connected to the air stream inlet end of the expansion generator subsystem reheater 15, the hot side cold storage stream inlet end of the evaporator 14 is connected to the cold storage outlet end of the cold storage subsystem, the hot side cold storage stream outlet end of the evaporator 14 is connected to the cold storage inlet end of the cold storage subsystem, the hot side BOG stream inlet end of the evaporator 14 is connected to the outlet of the BOG control valve 23, and the hot side outlet of the evaporator 14 is connected to the LNG buffer tank 24.

[0039] Furthermore, the evaporator 14, the BOG buffer tank 22 and the LNG buffer tank 24 form a BOG liquefaction circuit in the energy release stage; the high-grade cold energy carried by the low-temperature liquid air is provided to the BOG of the LNG receiving station through the heat exchange of the evaporator 14, so that the BOG is liquefied and refluxed and stored in the LNG buffer tank 24, thereby reducing the waste of BOG and the power consumption of the BOG compressor.

[0040] Furthermore, the liquid expander 8, throttle valve 9, gas-liquid separator 10, BOG condenser 21, evaporator 14, BOG buffer tank 22, LNG buffer tank 24, BOG control valve 23 and corresponding low-temperature pipelines all need to take effective thermal insulation measures or be placed inside the cold box body and filled with pearlescent sand for insulation.

[0041] Furthermore, the liquefied cold box 7, the low-temperature heat exchanger 5, the evaporator 14, and the BOG condenser 21 need to use low-temperature and high-pressure resistant materials, and the heat exchanger type is not limited to plate-fin type, shell-and-tube type, coiled-tube type, etc.

[0042] The liquid air storage tank subsystem includes a liquid air storage tank 12 and a cryogenic liquid pump 13, which are used to store and pump liquid air.

[0043] The inlet of the liquid air storage tank 12 is connected to the liquid outlet end of the gas-liquid separator 10, and the outlet of the liquid air storage tank 12 is connected to the cryogenic liquid pump 13. The outlet end of the cryogenic liquid pump 13 is connected to the evaporator 14. During the energy release stage, the liquid air in the liquid air storage tank 12 is pressurized and pumped to the evaporator 14.

[0044] Furthermore, the liquid air storage tank 12 has a complete pressure control system and related valves and pipelines; the liquid air storage tank 12 can be insulated by double-layer vacuum or placed in an insulation box together with the cryogenic liquid pump 13 and filled with pearlescent sand for insulation.

[0045] The cold storage subsystem includes a cold storage device 11 and related auxiliary facilities such as driving equipment, valves and pipelines, and is used to store and release cold energy.

[0046] Furthermore, the cold storage side is connected to the evaporator 14 through pipelines, valves, driving equipment, etc. to form a circulation loop. During the energy release stage, the cold energy released by the vaporization of liquid air is recovered and stored through the cold storage circulation loop.

[0047] Furthermore, its cold release side is connected to the liquefied cold box 7 through pipelines, valves, driving equipment, etc. to form a circulation loop. During the energy storage stage, cold energy is released through the cold release circulation loop, and the stored cold energy is provided to the liquefied cold box.

[0048] Furthermore, the tank body of the cold storage device 11 and the corresponding pipelines are placed in an insulation box and filled with pearl sand for insulation; the cold storage medium can be one or more of solid phase cold storage materials (rocks, metals, compounds and mixed materials, etc.), phase change cold storage materials, and low-temperature liquid cold storage materials; the cold storage method of the cold storage device 11 can be indirect or direct heat exchange with the air in the liquefied cold box 7 or the evaporator 14.

[0049] The expansion power generation subsystem includes a reheater 15, a preheater 16 and an expansion power generation unit 17, which is used to use high-temperature pressurized air to drive the expander to expand and perform work, thereby driving the generator to generate electricity.

[0050] The air stream inlet of the reheater 15 is connected to the air stream outlet of the evaporator 14 or the preheater outlet, and the outlet of the reheater 15 is connected to the inlet of the expansion generator set; the heat medium stream inlet of the reheater 15 is connected to the heat storage tank 19 and the hot water pump 20 of the heat storage subsystem, and the heat medium stream outlet of the reheater 15 is connected to the cold storage tank 18 of the heat storage subsystem; The air stream inlet end of the preheater 16 is connected to the outlet of the expansion generator set 17, and the air stream outlet end of the preheater 16 is connected to the air stream inlet end of the reheater 15, which is used to preheat the low-temperature air at the expander outlet to room temperature; the preheating heat source can be waste heat from other systems or waste heat from seawater.

[0051] The inlet of the expansion generator set 17 is connected to the reheater 15, and the high-temperature pressurized air is used to drive the multi-stage expander to expand and do work, thereby driving the generator to generate electricity.

[0052] Furthermore, the expansion generator set 17 can adopt a multi-stage expansion mode, and the reheater 15 and the preheater 16 are connected in series between the expansion machines of each stage to reheat the air.

[0053] Furthermore, during the energy release phase, the molecular sieve purifier needs to be regenerated. The clean air discharged from the expander outlet can be heated by compression heat or electric heating to hot-blow the molecular sieve purifier, and then cold-blow the clean air to complete the regeneration of the molecular sieve purifier 4.

[0054] The above is only a preferred specific implementation of the present invention; however, the protection scope of the present invention is not limited thereto. Any technician familiar with the technical field can make equivalent replacements or changes according to the technical solution and its improved conception within the technical scope disclosed by the present invention, which should be covered by the protection scope of the present invention.

Claims

1. A system for complementary liquid air energy storage and LNG cold energy, characterized in that: include: Compressor unit subsystem, heat storage subsystem, liquefied gasification subsystem, liquid air storage tank subsystem, cold storage subsystem and expansion subsystem The compressor unit subsystem comprises an air filter (1), a normal temperature compressor (2), a heat exchanger (3), a molecular sieve purifier (4), a low temperature heat exchanger (5), a low temperature compressor (6) and pipeline valves, and is used to compress air; The heat storage subsystem comprises a cold storage tank (18), a hot storage tank (19) and a water pump (20), which are used to store and circulate heat medium; The liquefaction and gasification subsystem comprises a liquefaction cold box (7), a liquid expander (8), a throttle valve (9), a gas-liquid separator (10), an evaporator (14), a BOG condenser (21), a BOG buffer tank (22), a BOG control valve (23) and an LNG buffer tank (24), and is used to realize the liquefaction and gasification of air and the recondensation and liquefaction of BOG; The liquid air storage tank subsystem comprises a liquid air storage tank (12) and a cryogenic liquid pump (13), which are used to store and pump liquid air; The cold storage subsystem comprises a cold storage device (11) and a driving device, a valve and a pipeline, and is used for storing and releasing cold energy; The expansion power generation subsystem comprises a reheater (15), a preheater (16) and an expansion power generation unit (17), and is used to utilize high-temperature pressurized air to drive the expander to expand and perform work, thereby driving the generator to generate electricity.

2. According to claim 1, a system for complementary liquid air energy storage and LNG cold energy, characterized in that: The outlet end of the air filter (1) is connected to the inlet end of the normal temperature compressor (2), the outlet end of the normal temperature compressor (2) is connected to the air medium stream inlet end of the heat exchanger (3), the outlet of the heat exchanger (3) is connected to the inlet end of the molecular sieve purifier (4), the heat medium stream inlet end of the heat exchanger (3) is connected to the cold storage tank (18) of the heat storage subsystem, and the heat medium stream outlet end of the interstage heat exchanger (3) is connected to the hot storage tank (19) of the heat storage subsystem; The air medium stream outlet end of the low-temperature heat exchanger (5) is connected to the inlet of the low-temperature compressor (6), the low-temperature medium stream inlet end of the low-temperature heat exchanger (5) is connected to the LNG pipeline on the high-pressure side of the LNG station, and the low-temperature medium stream outlet end of the low-temperature heat exchanger (5) is connected to the NG pipeline of the LNG station.

3. According to claim 1, a system for complementary liquid air energy storage and LNG cold energy, characterized in that: The water pump (20) comprises a cold water pump and a hot water pump. The cold storage tank (18) is used to store the heat medium before heat storage or after cooling. The inlet end of the cold storage tank (18) is connected to the outlet of the heat medium flow stream of the reheater (15) of the expansion power generation subsystem. The outlet of the cold storage tank (18) is connected to the cold water pump. The cold water pump is connected to the inlet end of the heat medium flow stream of the heat exchanger (3) of the compressor unit subsystem. The heat storage tank (19) is used to store the heat medium after heat storage. The outlet end of the heat storage tank (19) is connected to the hot water pump. The inlet end of the heat storage tank (19) is connected to the outlet of the heat exchanger (3) of the compressor unit subsystem. The hot water pump is connected to the inlet end of the heat medium flow of the reheater (15) of the expansion power generation subsystem.

4. According to claim 1, a system for complementary liquid air energy storage and LNG cold energy, characterized in that: The hot side air stream inlet end of the liquefied cold box (7) is connected to the outlet of the last section of the compressor unit subsystem, the hot side air stream outlet end of the liquefied cold box (7) is connected to the liquid expander (8), the cold side LNG stream inlet end of the liquefied cold box (7) is connected to the LNG pipeline on the high pressure side of the LNG station, and the cold side LNG stream outlet end of the liquefied cold box (7) is connected to the NG pipeline of the LNG station; the cold side cold storage stream inlet end of the liquefied cold box (7) is connected to the cold release outlet end of the cold storage subsystem, and the cold side cold storage stream outlet end of the liquefied cold box (7) is connected to the cold release inlet end of the cold storage subsystem; the cold side return air stream inlet end of the liquefied cold box (7) is connected to the air stream outlet of the BOG condenser (21), and the cold side air stream outlet end of the liquefied cold box (7) is connected to the inlet of the low-temperature compressor (6); The liquid expander (8) is connected to the liquefaction cold box (7) and the throttle valve (9); The inlet of the gas-liquid separator (10) is connected to the outlet of the throttle valve (9), the liquid air outlet of the gas-liquid separator (10) is connected to the liquid air storage tank subsystem, and the gaseous air outlet of the gas-liquid separator (10) is connected to the cold side air stream inlet of the BOG condenser (21); The BOG condenser (21) is used to realize the recondensation and liquefaction of BOG at the LNG receiving station. The cold side outlet of the BOG condenser (21) is connected to the cold side return air stream inlet end of the liquefaction cold box (7), the hot side inlet of the BOG condenser (21) is connected to the outlet of the BOG control valve (23), and the hot side outlet of the BOG condenser (21) is connected to the LNG buffer tank (24); The cold side air stream inlet end of the evaporator (14) is connected to the outlet of the low temperature liquid pump (13) of the liquid air storage tank system, the cold side air stream outlet end of the evaporator (14) is connected to the air stream inlet end of the expansion generator subsystem reheater (15), the hot side cold storage stream inlet end of the evaporator (14) is connected to the cold storage outlet end of the cold storage subsystem, the hot side cold storage stream outlet end of the evaporator (14) is connected to the cold storage inlet end of the cold storage subsystem, the hot side BOG stream inlet end of the evaporator (14) is connected to the outlet of the BOG control valve (23), and the hot side outlet of the evaporator (14) is connected to the LNG buffer tank (24).

5. According to claim 1, a system for complementary liquid air energy storage and LNG cold energy, characterized in that: The inlet of the liquid air storage tank (12) is connected to the liquid outlet end of the gas-liquid separator (10), the outlet of the liquid air storage tank (12) is connected to the cryogenic liquid pump (13), and the outlet end of the cryogenic liquid pump (13) is connected to the evaporator (14).

6. A system for complementary liquid air energy storage and LNG cold energy according to claim 1, characterized in that: The air stream inlet end of the reheater (15) is connected to the air stream outlet of the evaporator (14) or the preheater outlet, and the outlet end of the reheater (15) is connected to the inlet of the expansion generator set; the heat medium stream inlet end of the reheater (15) is connected to the heat storage tank (19) and the hot water pump 20 of the heat storage subsystem, and the heat medium stream outlet end of the reheater (15) is connected to the cold storage tank (18) of the heat storage subsystem; The air stream inlet end of the preheater (16) is connected to the outlet of the expansion generator set (17), and the air stream outlet end of the preheater (16) is connected to the air stream inlet end of the reheater (15).

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