Liquid air energy storage and liquefied natural gas coupling efficient power generation device and method

Abstract

The invention relates to the field of liquid air energy storage, and discloses a liquid air energy storage and liquefied natural gas coupling efficient power generation device and method. The method comprises the steps that an air liquefaction circulation loop purifies, compresses and cools ambient air and then expands and decompresses the ambient air to obtain liquid air, and the liquid air is transmitted to an air power generation circulation loop; generated air compression heat is stored in the heat storage unit; the air power generation circulation loop generates power through expansion of received liquid air, and generated cold energy is stored in a cold storage unit; the LNG vaporization supply loop pressurizes, evaporates and gasifies liquefied natural gas and then supplies the liquefied natural gas to a user side, generated cold energy is stored in a cold storage unit or directly supplied to the air liquefaction circulation loop, and meanwhile gaseous natural gas naturally released by an LNG tank is collected and conveyed to a combustion chamber. The high-grade heat energy utilization loop conducts heat conduction oil circulation, low-grade heat energy and high-grade natural gas combustion heat energy of the heat storage unit are recycled in sequence, high-grade heat energy is transmitted to the air power generation circulation loop, and heat conduction oil returns to the initial state to continue circulation after releasing the heat energy.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid air energy storage, and in particular to a liquid air energy storage and liquefied natural gas coupled high-efficiency power generation device and method. Background Art

[0002] As an important technical reserve for large-scale energy storage, liquid air energy storage has attracted the attention of more and more experts and scholars due to its advantages such as being not restricted by geographical conditions, high energy storage density, and environmental friendliness. The liquid air energy storage system uses liquid air or nitrogen as the "electricity storage medium" and also includes a complex heat storage and cold storage process. Its basic operating principle is: the surplus electricity of the power grid drives the compressor to work, carry out the air liquefaction process, store electricity in the form of liquid air, and store the compression heat; when it is necessary to supply power to the outside world, the liquid air is pressurized by a cryogenic pump and the cryogenic cold energy is recovered, and then the air generator expander is driven to generate electricity.

[0003] In the liquid air energy storage system, the recycling of low-temperature cold energy and high-temperature heat energy is the key to improving the system's cycle power generation efficiency. However, in an independent liquid air energy storage system, both low-temperature cold energy and high-temperature heat energy are lacking, making the system's cycle power generation efficiency only about 50%, limiting the development of liquid air energy storage technology. Many experts and scholars have noticed that integrating the LNG energy station with the liquid air energy storage system, using the vaporization cold energy of LNG to increase the liquefaction rate of the air liquefaction process and using the heat of natural gas combustion to increase the power generation of the expander are effective means to improve the system's cycle power generation efficiency. In the liquid air energy storage system that utilizes LNG cold energy and gas peak-shaving power generation waste heat disclosed in the patent document with publication number CN112254561B, it is pointed out that the LNG vaporization cold energy is used to reduce the air temperature before entering the compressor, thereby reducing the power consumption of the compressor. In addition, the heat generated by the combustion of natural gas after vaporization is used to heat the air temperature before entering the power generation expander, thereby increasing the work of the expander and ultimately improving the system's cycle power generation efficiency. However, the integrated system of LNG and liquid air energy storage still has the following technical problems: ① From From an analytical perspective, LNG high-grade vaporization refrigeration It should be used in places where high-quality cold energy is urgently needed (such as deep cooling of imported high-pressure air in a cold box). The temperature difference between the hot end and the cold end of the heat exchanger and the heat exchange temperature difference should not be too large; ② When the recovered compressed heat grade is not high enough, the heat generated by the combustion of natural gas is used to continue to increase the heat source grade to further heat the air temperature before entering the power expansion machine, which can improve the system's cycle power generation efficiency and cogeneration efficiency. However, natural gas is often not free to use. Summary of the invention

[0004] In view of the above problems, the purpose of the present invention is to provide a liquid air energy storage and liquefied natural gas coupling high-efficiency power generation device and method, which can maximize the utilization of LNG resources and improve the system cycle power generation efficiency.

[0005] To achieve the above objectives, in the first aspect, the technical solution adopted by the present invention is: a liquid air energy storage and liquefied natural gas coupled high-efficiency power generation device, which includes: an air liquefaction circulation loop, an air power generation circulation loop, an LNG vaporization supply loop and a high-grade thermal energy utilization loop; the air liquefaction circulation loop is used to purify, compress and cool the ambient air, expand and reduce the pressure to obtain liquid air, and the liquid air is transmitted to the air power generation circulation loop, and the air compression heat generated in the compression process is stored in the heat storage unit; the air power generation circulation loop pressurizes, evaporates and vaporizes the received liquid air, and further heats it to expand and generate electricity, and the liquid air vaporization process generates The cold energy is stored in the cold storage unit; the LNG vaporization supply loop supplies the liquefied natural gas to the user side after pressurization, evaporation and gasification. The cold energy generated in the liquefied natural gas vaporization process is stored in the cold storage unit or directly supplied to the air liquefaction circulation loop. At the same time, the gaseous natural gas naturally released by the LNG tank is effectively collected and transmitted to the combustion chamber in the high-grade thermal energy utilization loop according to usage needs; the high-grade thermal energy utilization loop is driven by a pump to circulate the heat transfer oil, first recovering the lower-grade heat energy of the heat storage unit, then recovering the high-grade natural gas combustion heat energy, and finally transferring the high-grade heat energy to the air power generation circulation loop. After the heat transfer oil releases the heat energy, it returns to the initial state and continues to circulate.

[0006] Furthermore, the air liquefaction circulation loop includes a cold storage unit, a heat storage unit, an air compressor unit, an air purification unit, a cold box, a low-temperature expander, a low-temperature throttle valve, a gas-liquid separator and a liquid air storage tank; the cold storage unit is provided in two: a first cold storage unit and a second cold storage unit;

[0007] The first input end of the air compressor group is used to input ambient air, and the first output end of the air compressor group is connected to the first input end of the cold box; the second output end of the air compressor group is connected to the first input end of the air purification unit, and the second input end of the air compressor group is connected to the first output end of the air purification unit; the third input end of the air compressor group is connected to the first output end of the heat storage unit, and the third output end of the air compressor group is connected to the first input end of the heat storage unit, and the fourth input end of the air compressor group is connected to the second output end of the cold box;

[0008] The air purification unit includes a precooler and a molecular sieve adsorption bed; the first output end of the cold box is connected to the input end of the low-temperature expander, and the second input end of the cold box is connected to the second output end of the gas-liquid separator; the third input end of the cold box is connected to the first output end of the first cold storage unit, and the third output end of the cold box is connected to the first input end of the first cold storage unit; the fourth input end of the cold box is connected to the second output end of the second cold storage unit, and the fourth output end of the cold box is connected to the second input end of the second cold storage unit;

[0009] The output end of the cryogenic expander is connected to the input end of the gas-liquid separator via a cryogenic throttle valve, and the first output end of the gas-liquid separator is connected to the liquid air storage tank.

[0010] Further, the first cold storage unit is located at the lower side of the cold box; the second cold storage unit is located at the lower side of the cold box, or is arranged at the upper side of the cold box;

[0011] When the first cold storage unit and the second cold storage unit adopt a parallel structure, the second cold storage unit is arranged on the upper side of the cold box, and the LNG cold energy is independently stored in the second cold storage unit; when the first cold storage unit and the second cold storage unit adopt a series structure, the second cold storage unit is arranged on the lower side of the cold box, and the LNG cold energy is coupled with the cold energy of vaporization of a partial temperature zone of liquid air and stored in the second cold storage unit, and the first cold storage unit and the second cold storage unit form a series ladder temperature cold energy storage.

[0012] Further, the air power generation cycle loop includes a cold storage unit, a liquid air storage tank, a first cryogenic liquid pump, an evaporator, a high-grade heat energy utilization unit and a power generation expansion unit;

[0013] The input end of the first cryogenic liquid pump is connected to the output end of the liquid air storage tank, and the output end of the first cryogenic liquid pump is connected to the first input end of the evaporator;

[0014] The first output end of the evaporator is connected to the first input end of the power generation expansion unit, the second output end of the evaporator is connected to the third input end of the first cold storage unit, and the second input end of the evaporator is connected to the third output end of the first cold storage unit;

[0015] The first output end of the power generation expansion unit is connected to the external environment, the second input end of the power generation expansion unit is connected to the first output end of the high-grade thermal energy utilization unit, and the second output end of the power generation expansion unit is connected to the first input end of the high-grade thermal energy utilization unit.

[0016] Furthermore, the LNG vaporization supply circuit is an LNG vaporization supply unit, comprising:

[0017] LNG storage tank, LNG storage tank has a liquid outlet and an exhaust port; the liquid outlet is used to discharge liquefied natural gas to the outside; the exhaust port is used to maintain the pressure balance of the tank body, and the discharged gaseous natural gas is effectively collected and burned to obtain high-grade heat energy to improve the efficiency of the power generation expander;

[0018] a second cryogenic liquid pump, wherein an input end of the second cryogenic liquid pump is connected to a liquid outlet of the LNG storage tank;

[0019] LNG vaporizer, the first input end of the LNG vaporizer is connected to the output end of the second cryogenic liquid pump, the first output end of the LNG vaporizer is connected to the user side as the third output end of the LNG vaporization supply unit; the second input end of the LNG vaporizer is connected to the fourth output end of the second cold storage unit as the first input end of the LNG vaporization supply unit, and the second output end of the LNG vaporizer is connected to the fourth input end of the second cold storage unit as the first output end of the LNG vaporization supply unit;

[0020] A natural gas collecting tank, the input end of which is connected to the exhaust port of the LNG storage tank, and the output end of which, as the second output end of the LNG vaporization supply unit, is connected to the third input end of the high-grade thermal energy utilization unit.

[0021] Furthermore, the heat storage unit comprises:

[0022] A normal temperature water tank having an upper port and a lower port, wherein the lower port serves as a second input end of the heat storage unit and is connected to a second output end of the high-grade heat energy utilization unit;

[0023] A first radiator, wherein an input end of the first radiator is connected to an upper port of the normal temperature water tank;

[0024] A first water pump, wherein an input end of the first water pump is connected to an output end of the first radiator, and an output end of the first water pump is connected to a third input end of the air compressor unit as a first output end of the heat storage unit;

[0025] A hot water tank having an upper port and a lower port, wherein the upper port serves as a first input end of the heat storage unit and is connected to a third output end of the air compressor unit;

[0026] A second water pump, the input end of the second water pump is connected to the lower port of the hot water tank, and the output end of the second water pump is connected to the second input end of the high-quality thermal energy utilization unit as the second output end of the heat storage unit.

[0027] Furthermore, the high-grade heat energy utilization loop is a high-grade heat energy utilization unit, including:

[0028] Oil replenishment tank, used to replenish hot oil working medium to the circulation;

[0029] An oil pump, arranged on the oil outlet pipeline of the oil replenishment tank, is used to provide power for the working medium circulation;

[0030] An oil-water heat exchanger, wherein a first input end of the oil-water heat exchanger is connected to an output end of the oil pump, a second input end of the oil-water heat exchanger is connected to a second output end of the heat storage unit as a second input end of the high-quality heat energy utilization unit, and a second output end of the oil-water heat exchanger is connected to a second input end of the heat storage unit as a second output end of the high-quality heat energy utilization unit;

[0031] A combustion chamber, wherein the first input end of the combustion chamber is connected to the second output end of the LNG vaporization supply unit as the third input end of the high-grade thermal energy utilization unit, the first output end of the combustion chamber is connected to the external environment as the third output end of the high-grade thermal energy utilization unit, the second input end of the combustion chamber is connected to the first output end of the oil-water heat exchanger, and the second output end of the combustion chamber is connected to the second input end of the power generation expansion unit as the first output end of the high-grade thermal energy utilization unit;

[0032] The second radiator, the input end of the second radiator is connected to the second output end of the power generation expansion unit as the first input end of the high-grade thermal energy utilization unit, and the output end of the second radiator is connected to the input end of the oil pump.

[0033] Further, the first cold storage unit comprises:

[0034] A first solid cold storage tank assembly having an upper port and a lower port;

[0035] A first air supply tank, which is connected in parallel with the first solid cold storage tank group and is used for circulating air supply;

[0036] A first circulation fan, wherein an input end of the first circulation fan is connected to an upper port of the first solid cold storage tank group;

[0037] a first cold fluid three-way valve, wherein a first port of the first cold fluid three-way valve is connected to an output end of the first circulation fan, a second port of the first cold fluid three-way valve is connected to a third output end of the cold box as a first input end of the cold storage unit, and a third port of the first cold fluid three-way valve is connected to a second input end of the evaporator as a third output end of the cold storage unit;

[0038] A second cold fluid three-way valve, wherein the first port of the second cold fluid three-way valve is connected to the lower port of the first solid cold storage tank group, the second port of the second cold fluid three-way valve is connected to the third input end of the cold box as the first output end of the cold storage unit, and the third port of the first cold fluid three-way valve is connected to the second output end of the evaporator as the third input end of the cold storage unit;

[0039] The second cold storage unit comprises:

[0040] a second solid cold storage tank assembly having an upper port and a lower port;

[0041] A second air supply tank, which is connected in parallel with the second solid cold storage tank group and is used for circulating air supply;

[0042] a third cold fluid three-way valve, wherein a first port of the third cold fluid three-way valve is connected to an upper port of the second solid cold storage tank group;

[0043] A second circulation fan, wherein the output end of the second circulation fan is connected to the second port of the third cold fluid three-way valve, and the input end of the second circulation fan is connected to the fourth output end of the cold box as the second input end of the second cold storage unit;

[0044] A fourth cold fluid three-way valve, wherein the first port of the fourth cold fluid three-way valve is connected to the lower port of the second solid cold storage tank group, the second port of the second cold fluid three-way valve is connected to the fourth input end of the cold box as the second output end of the second cold storage unit, and the third port of the fourth cold fluid three-way valve is connected to the first output end of the LNG vaporization supply unit as the fourth input end of the cold storage unit;

[0045] The third circulation fan, the input end of the third circulation fan is connected to the first input end of the LNG vaporization supply unit as the fourth output end of the cold storage unit, and the output end of the third circulation fan is connected to the third port of the third cold fluid three-way valve.

[0046] Furthermore, when the first cold storage unit and the second cold storage unit are connected in parallel, the LNG vaporization cold energy is fully utilized in the temperature range in the cold box; when connected in series, the LNG vaporization cold energy is only utilized in a part of the temperature range in the cold box, and high-grade low-temperature cold energy is provided by liquid air.

[0047] In the second aspect, the technical solution adopted by the present invention is: a liquid air energy storage method that utilizes LNG cold energy and combustion heat energy to improve cycle efficiency, which is realized based on the above-mentioned liquid air energy storage and liquefied natural gas coupling high-efficiency power generation device, and includes: an air liquefaction cycle process, an air power generation cycle process, an LNG vaporization supply process, and a high-grade thermal energy utilization process;

[0048] Air liquefaction cycle process: ambient air is pressurized and inter-stage cooled by the compressor unit, purified by the air purification unit, cooled in the cold box, expanded, throttled, and separated into liquid form before being stored in a liquid air storage tank; the air compression heat is stored in the heat storage unit;

[0049] Air power generation cycle: the liquid air output from the liquid air storage tank is pressurized to high pressure by the first cryogenic liquid pump, enters the evaporator to undergo a liquid-gas phase change process, and then enters the power generation expander to generate power; the cold energy of the liquid air vaporization is stored in the cold storage unit;

[0050] LNG vaporization supply process: The liquefied natural gas output from the LNG storage tank is pressurized by the second cryogenic liquid pump, enters the LNG vaporizer for vaporization, and then delivers natural gas to the user's pipeline network. The waste natural gas naturally discharged from the LNG storage tank is collected by the natural gas collection tank. At the same time, the cold energy of LNG vaporization is used in the cold box to cooperate with the cold energy of liquid air vaporization to further cool the inlet air, so as to obtain a higher air liquefaction rate and system cycle efficiency;

[0051] High-grade thermal energy utilization process: The oil pump drives the heat transfer oil to circulate, and the lower-grade thermal energy is extracted from the heat storage unit through the oil-water heat exchanger. The higher-grade thermal energy is then obtained by burning natural gas in the combustion chamber. The heat transfer oil circulation is used to transfer high-quality thermal energy to the front inlet air of the power generation expander, thereby obtaining higher expansion power generation power and system cycle efficiency.

[0052] The present invention adopts the above technical solution, which has the following advantages:

[0053] 1. The present invention utilizes the cold energy of LNG vaporization and the heat energy of combustion to act synergistically on the system, effectively improving the system's cycle power generation efficiency.

[0054] 2. The present invention proposes two cold storage schemes, parallel and series, and related control methods to achieve effective integrated application of LNG cold energy in liquid air energy storage systems.

[0055] 3. The present invention collects and utilizes the waste natural gas naturally discharged from LNG storage tanks, which is environmentally friendly and enables free acquisition of gas resources.

[0056] In summary, the present invention utilizes the collected waste natural gas to burn in the combustion chamber, and the combustion heat energy is effectively obtained and transferred to the inlet air before the power generation expander, greatly improving the power generation expander power; on the other hand, the recovered LNG vaporization cold energy is combined with the liquid air vaporization cold energy to cool the inlet air in the cold box to the maximum extent, effectively improving the air liquefaction rate. In order to achieve efficient recycling of LNG cold energy, the present invention provides optional parallel and series cold storage solutions, which can be controlled by valves for cold storage. BRIEF DESCRIPTION OF THE DRAWINGS

[0057] Figure 1 It is a schematic structural diagram of a cold storage tank group parallel type liquid air energy storage device in one embodiment of the present invention;

[0058] Figure 2 This is a schematic structural diagram of a cold storage tank group series-connected liquid air energy storage device in one embodiment of the present invention;

[0059] Reference numerals:

[0060] Air compressor unit 100, first compressor 101, first cooler 102, second compressor 103, second cooler 104, third compressor 105, third cooler 106, fourth compressor 107, fourth cooler 108;

[0061] Air purification unit 200, precooler 201, molecular sieve adsorption bed 202;

[0062] Cold box 301, cryogenic expander 302, cryogenic throttle valve 303, gas-liquid separator 304;

[0063] Liquid air storage tank 401, first cryogenic liquid pump 402, evaporator 403;

[0064] A power generation expander unit 500, a first heater 501, a first power generation expander 502, a second heater 503, a second power generation expander 504, a third heater 505, a third power generation expander 506, a fourth heater 507, and a fourth power generation expander 508;

[0065] Cold storage unit 600, first solid cold storage tank group 601, first air supply tank 602, first circulation fan 603, first cold fluid three-way valve 604, second cold fluid three-way valve 605, second solid cold storage tank group 606, second air supply tank 607, third cold fluid three-way valve 608, second circulation fan 609, fourth cold fluid three-way valve 610, third circulation fan 611;

[0066] Heat storage unit 700, normal temperature water tank 701, first radiator 702, first water pump 703, hot water tank 704, second water pump 705;

[0067] High-grade heat energy utilization unit 800, oil replenishment tank 801, oil pump 802, oil-water heat exchanger 803, combustion chamber 804, second radiator 805;

[0068] LNG vaporization supply unit 900 , LNG storage tank 901 , second cryogenic liquid pump 902 , LNG vaporizer 903 , and natural gas collection tank 904 . DETAILED DESCRIPTION

[0069] In order to make the purpose, technical solution and advantages of the embodiment of the present invention clearer, the technical solution of the embodiment of the present invention will be clearly and completely described below in conjunction with the drawings of the embodiment of the present invention. Obviously, the described embodiment is a part of the embodiment of the present invention, not all of the embodiments. Based on the described embodiment of the present invention, all other embodiments obtained by ordinary technicians in this field belong to the scope of protection of the present invention.

[0070] It should be noted that the terms used herein are only for describing specific embodiments and are not intended to limit the exemplary embodiments according to the present application. As used herein, unless the context clearly indicates otherwise, the singular form is also intended to include the plural form. In addition, it should be understood that when the terms "comprise" and / or "include" are used in this specification, it indicates the presence of features, steps, operations, devices, components and / or combinations thereof.

[0071] The present invention relates to a liquid air energy storage device and method that utilizes LNG cold energy and combustion heat energy to improve cycle efficiency; during the off-peak period of electricity consumption, the ambient air is purified, compressed and cooled, and then expanded and depressurized to obtain liquid air, while recovering and storing the air compression heat energy; during the peak period of electricity consumption, the liquid air is pressurized, evaporated, vaporized and heated, and then enters the power generation expansion unit to generate electricity, while recovering and storing the liquid air vaporization cold energy; while the LNG vaporization supply process continues to operate, the LNG vaporization cold energy can both instantly enhance the air liquefaction process and be stored in the cold storage unit. The present invention utilizes LNG vaporization cold energy to further improve the air liquefaction rate and utilizes waste natural gas combustion heat energy to further improve the air power generation power. Through two series and parallel cold storage schemes and related controls, the LNG resources are maximized, and the purpose of effectively improving the cycle power generation efficiency of the liquid air energy storage system is finally achieved.

[0072] Example 1: In this example, a liquid air energy storage and liquefied natural gas coupling high-efficiency power generation device is provided, which utilizes the cold energy of liquefied natural gas and the heat energy of combustion to improve the cycle efficiency. Figure 1 , Figure 2 As shown, the device includes: an air liquefaction circulation loop, an air power generation circulation loop, an LNG vaporization supply loop and a high-grade thermal energy utilization loop.

[0073] The air liquefaction circulation loop is used to purify, compress and cool the ambient air, expand and reduce the pressure to obtain liquid air, and the liquid air is transmitted to the air power generation circulation loop, and the air compression heat generated during the compression process is stored in the heat storage unit 700;

[0074] The air power generation cycle pressurizes, evaporates and further heats the received liquid air to expand and generate electricity, and the cold energy generated by the liquid air vaporization process is stored in the cold storage unit 600;

[0075] The LNG vaporization supply loop supplies liquefied natural gas to the user side after pressurization, evaporation and gasification. The cold energy generated during the liquefied natural gas vaporization process is stored in the cold storage unit 600 or directly supplied to the air liquefaction circulation loop. At the same time, the gaseous natural gas naturally released by the LNG tank is effectively collected and transmitted to the combustion chamber 804 in the high-grade heat energy utilization loop according to the use demand;

[0076] The high-grade heat energy utilization loop is driven by a pump to circulate the heat transfer oil, first recovering the lower-grade heat energy of the heat storage unit 700, then recovering the high-grade natural gas combustion heat energy, and finally transferring the high-grade heat energy to the air power generation circulation loop. After the heat transfer oil releases the heat energy, it returns to the initial state and continues to circulate.

[0077] In an optional embodiment, the air liquefaction circulation loop includes, in addition to the cold storage unit 600 and the heat storage unit 700, an air compressor unit 100, an air purification unit 200, a cold box 301, a low-temperature expander 302, a low-temperature throttle valve 303, a gas-liquid separator 304 and a liquid air storage tank 401. The cold storage unit 600 is provided in two parts: a first cold storage unit 600 and a second cold storage unit 600.

[0078] The first input end 1 of the air compressor group 100 is used to input ambient air, and the first output end of the air compressor group 100 is connected to the first input end 12 of the cold box 301; the second output end 5 of the air compressor group 100 is connected to the first input end of the air purification unit 200, and the second input end 7 of the air compressor group 100 is connected to the first output end of the air purification unit 200; the third input end H1 of the air compressor group 100 is connected to the first output end of the heat storage unit 700, the third output end H6 of the air compressor group 100 is connected to the first input end of the heat storage unit 700, and the fourth input end 8 of the air compressor group 100 is connected to the second output end 18 of the cold box 301.

[0079] The air purification unit 200 mainly includes a precooler 201 and a molecular sieve adsorption bed 202; the first output end 13 of the cold box 301 is connected to the input end of the low-temperature expander 302, and the second input end 17 of the cold box 301 is connected to the second output end of the gas-liquid separator 304; the third input end C1 of the cold box 301 is connected to the first output end of the first cold storage unit 600, and the third output end C2 of the cold box 301 is connected to the first input end of the first cold storage unit 600; the fourth input end C5 of the cold box 301 is connected to the second output end of the second cold storage unit 600, and the fourth output end C6 of the cold box 301 is connected to the second input end of the second cold storage unit 600.

[0080] The output end of the cryogenic expander 302 is connected to the input end of the gas-liquid separator 304 via the cryogenic throttle valve 303. Specifically, the output end of the cryogenic expander 302 is connected to the input end 14 of the cryogenic throttle valve 303, and the output end 15 of the cryogenic throttle valve 303 is connected to the input end of the gas-liquid separator 304; the first output end 16 of the gas-liquid separator 304 is connected to the liquid air storage tank 401.

[0081] In this embodiment, the first cold storage unit 600 is located at the lower side of the cold box 301; the second cold storage unit 600 can be located at the lower side of the cold box 301, or can be set at the upper side of the cold box 301. When the first cold storage unit 600 and the second cold storage unit 600 adopt a parallel structure, the second cold storage unit 600 is set at the upper side of the cold box 301, and the LNG cold energy is independently stored in the second cold storage unit 600; when the first cold storage unit 600 and the second cold storage unit 600 adopt a series structure, the second cold storage unit 600 is set at the lower side of the cold box 301, and the LNG cold energy is coupled with the liquid air partial temperature zone vaporization cold energy and stored in the second cold storage unit 600, and the first cold storage unit 600 and the second cold storage unit 600 form a series ladder temperature cold energy storage.

[0082] In the above embodiment, the air compressor unit 100 includes:

[0083] A first compressor 101, wherein an input end of the first compressor 101 serves as a first input end 1 of the air compressor unit 100, and is used to input ambient air;

[0084] A first cooler 102, wherein a first input end 2 of the first cooler 102 is connected to an output end of the first compressor 101;

[0085] A second compressor 103, the second compressor 103 is connected in series with the first compressor 101, and an input terminal 3 of the second compressor 103 is connected to a first output terminal of the first cooler 102;

[0086] A second cooler 104, wherein a first input end of the second cooler 104 is connected to an output end 4 of the second compressor 103; a first output end 5 of the second cooler 104, as a second output end 5 of the air compressor unit 100, is connected to a first input end of the air purification unit 200;

[0087] A third compressor 105, the input end of the third compressor 105 serves as the second input end 7 and the fourth input end 8 of the air compressor unit 100, and is connected to the first output end of the air purification unit 200 and the second output end 18 of the cold box 301 respectively;

[0088] A third cooler 106, wherein a first input end of the third cooler 106 is connected to an output end 9 of the third compressor 105;

[0089] A fourth compressor 107 is connected in series with the third compressor 105 , and an input end 10 of the fourth compressor 107 is connected to a first output end of the third cooler 106 ;

[0090] A fourth cooler 108, wherein a first input end of the fourth cooler 108 is connected to an output end 11 of a fourth compressor 107, and a first output end of the fourth cooler 108 is connected to a first input end 12 of a cold box 301 as a first output end of an air compressor unit 100;

[0091] The second input end of the first cooler 102, the second input end of the second cooler 104, the second input end of the third cooler 106 and the second input end of the fourth cooler 108 are connected in parallel as the third input end H1 of the air compressor group 100, which is connected to the first output end of the heat storage unit 700; the second output end H2 of the first cooler 102, the second output end H3 of the second cooler 104, the second output end H4 of the third cooler 106 and the second output end H5 of the fourth cooler 108 are connected in parallel as the third output end H6 of the air compressor group 100, which is connected to the first input end of the heat storage unit 700.

[0092] In an optional embodiment, the air power generation cycle loop includes, in addition to the cold storage unit 600 and the liquid air storage tank 401 , a first cryogenic liquid pump 402 , an evaporator 403 , a high-grade thermal energy utilization unit 800 and a power generation expansion unit 500 .

[0093] The input end 19 of the first cryogenic liquid pump 402 is connected to the output end of the liquid air storage tank 401 , and the output end 20 of the first cryogenic liquid pump 402 is connected to the first input end of the evaporator 403 ;

[0094] The first output end 21 of the evaporator 403 is connected to the first input end of the power generation expansion unit 500, the second output end C4 of the evaporator 403 is connected to the third input end of the first cold storage unit 600, and the second input end C3 of the evaporator 403 is connected to the third output end of the first cold storage unit 600;

[0095] The first output end 29 of the power generation expansion unit 500 is connected to the external environment, the second input end H11 of the power generation expansion unit 500 is connected to the first output end of the high-grade thermal energy utilization unit 800, and the second output end H16 of the power generation expansion unit 500 is connected to the first input end of the high-grade thermal energy utilization unit 800.

[0096] In the above embodiment, the power generation expansion unit 500 includes:

[0097] A first heater 501, wherein a first input end of the first heater 501 serves as a first input end of the power generation expansion unit 500 and is connected to a first output end of the evaporator 403;

[0098] A first power-generating expander 502, wherein an input end of the first power-generating expander 502 is connected to a first output end 22 of the first heater 501;

[0099] A second heater 503, wherein a first input end 23 of the second heater 503 is connected to an output end of the first power generation expander 502;

[0100] A second power-generating expander 504, wherein an input end of the second power-generating expander 504 is connected to a first output end 24 of the second heater 503;

[0101] A third heater 505, wherein a first input end 25 of the third heater 505 is connected to an output end of the second power generation expander 504;

[0102] A third power-generating expander 506, wherein the input end of the third power-generating expander 506 is connected to the first output end 26 of the third heater 505;

[0103] a fourth heater 507, wherein the first input end 27 of the fourth heater 507 is connected to the output end of the third power generation expander 506;

[0104] The fourth power-generating expander 508 has its input end connected to the first output end 28 of the fourth heater 507 , and its output end is connected to the external environment as the first output end 29 of the power-generating expander group 500 .

[0105] The second input end of the first heater 501, the second input end of the second heater 503, the second input end of the third heater 505 and the second input end of the fourth heater 507 are connected in parallel as the second input end of the power generation expansion unit 500 as the second input end H11 of the power generation expansion unit 500, and are connected to the first output end of the high-quality thermal energy utilization unit 800; the second output end H12 of the first heater 501, the second output end H13 of the second heater 503, the second output end H14 of the third heater 505 and the second output end H15 of the fourth heater 507 are connected in parallel as the second output end H16 of the power generation expansion unit 500, and are connected to the first input end of the high-quality thermal energy utilization unit 800.

[0106] In an optional embodiment, the LNG vaporization supply circuit is an LNG vaporization supply unit 900, which includes:

[0107] LNG storage tank 901, LNG storage tank 901 has a liquid outlet L1 and an exhaust port; the liquid outlet L1 is used to discharge liquefied natural gas to the outside; the exhaust port is to maintain the pressure balance of the tank body, wherein the discharged gaseous natural gas is effectively collected and burned to obtain high-grade thermal energy for improving the efficiency of the power generation expander.

[0108] A second cryogenic liquid pump 902, the input end of the second cryogenic liquid pump 902 is connected to the liquid outlet L1 of the LNG storage tank 901;

[0109] LNG vaporizer 903, the first input end L2 of the LNG vaporizer 903 is connected to the output end of the second cryogenic liquid pump 902, and the first output end L3 of the LNG vaporizer 903 is connected to the user side as the third output end of the LNG vaporization supply unit 900; the second input end C7 of the LNG vaporizer 903 is connected to the fourth output end of the second cold storage unit 600 as the first input end of the LNG vaporization supply unit 900, and the second output end C8 of the LNG vaporizer 903 is connected to the fourth input end of the second cold storage unit 600 as the first output end of the LNG vaporization supply unit 900;

[0110] The natural gas collecting tank 904 has an input end connected to the exhaust port of the LNG storage tank 901 , and an output end of the natural gas collecting tank 904 is connected to the third input end of the high-grade thermal energy utilization unit 800 as the second output end of the LNG vaporization supply unit 900 .

[0111] In the above embodiments, the heat storage unit 700 includes:

[0112] A normal temperature water tank 701, which has an upper port and a lower port, wherein the lower port serves as a second input end of the heat storage unit 700 and is connected to a second output end H8 of the high-quality thermal energy utilization unit 800;

[0113] A first radiator 702, wherein an input end of the first radiator 702 is connected to an upper port of the normal temperature water tank 701;

[0114] A first water pump 703, wherein the input end of the first water pump 703 is connected to the output end of the first radiator 703, and the output end of the first water pump 703 is connected to the third input end H1 of the air compressor unit 100 as the first output end of the heat storage unit 700;

[0115] The hot water tank 704 has an upper port and a lower port, wherein the upper port serves as a first input port of the heat storage unit 700 and is connected to a third output port H6 of the air compressor unit 100;

[0116] The second water pump 705, the input end of the second water pump 705 is connected to the lower port of the hot water tank 704, and the output end of the second water pump 705 is connected to the second input end H7 of the high-quality thermal energy utilization unit 800 as the second output end of the heat storage unit 700.

[0117] In an optional embodiment, the high-grade thermal energy utilization loop is a high-grade thermal energy utilization unit 800, which includes:

[0118] The oil replenishment tank 801 is used to replenish the hot oil working medium to the circulation;

[0119] The oil pump 802 is arranged on the oil outlet pipeline of the oil replenishment tank 801 and is used to provide power for the working medium circulation;

[0120] An oil-water heat exchanger 803, wherein a first input end H9 of the oil-water heat exchanger 803 is connected to an output end of the oil pump 802, a second input end H7 of the oil-water heat exchanger 803 is connected to a second output end of the heat storage unit 700 as a second input end H7 of the high-quality thermal energy utilization unit 800, and a second output end H8 of the oil-water heat exchanger 803 is connected to a second input end of the heat storage unit 700 as a second output end H8 of the high-quality thermal energy utilization unit 800;

[0121] Combustion chamber 804, the first input end of combustion chamber 804 is connected to the second output end of LNG vaporization supply unit 900 as the third input end of high-grade thermal energy utilization unit 800, the first output end of combustion chamber 804 is connected to the external environment as the third output end of high-grade thermal energy utilization unit 800, the second input end of combustion chamber 804 is connected to the first output end H10 of oil-water heat exchanger 803, the second output end of combustion chamber 804 is connected to the second input end H11 of power generation expansion unit 500 as the first output end of high-grade thermal energy utilization unit 800;

[0122] The second radiator 805 , the input end of the second radiator 805 is connected to the second output end H16 of the power generation expansion unit 500 as the first input end of the high-grade thermal energy utilization unit 800 , and the output end of the second radiator 805 is connected to the input end of the oil pump 802 .

[0123] In the above embodiments, the first cold storage unit 600 includes:

[0124] A first solid cold storage tank group 601 having an upper port and a lower port;

[0125] A first air supply tank 602, which is connected in parallel with the first solid cold storage tank group 601, is used for circulating air supply; a control valve is provided on the pipeline connecting the first air supply tank 602 and the first solid cold storage tank group 601;

[0126] A first circulation fan 603, wherein an input end of the first circulation fan 603 is connected to an upper port of the first solid cold storage tank group 601;

[0127] A first cold fluid three-way valve 604, wherein a first port of the first cold fluid three-way valve 604 is connected to an output end of the first circulation fan 603, a second port of the first cold fluid three-way valve 604 is connected to a third output end C2 of the cold box 301 as a first input end of the cold storage unit 600, and a third port of the first cold fluid three-way valve 604 is connected to a second input end C3 of the evaporator 403 as a third output end of the cold storage unit 600;

[0128] The second cold fluid three-way valve 605, the first port of the second cold fluid three-way valve 605 is connected to the lower port of the first solid cold storage tank group 601, the second port of the second cold fluid three-way valve 605 is connected to the third input terminal C1 of the cold box 301 as the first output terminal of the cold storage unit 600, and the third port of the first cold fluid three-way valve 602 is connected to the second output terminal C4 of the evaporator 403 as the third input terminal of the cold storage unit 600.

[0129] In the above embodiments, the second cold storage unit 600 includes:

[0130] A second solid cold storage tank set 606 having an upper port and a lower port;

[0131] A second air supply tank 607, which is connected in parallel with the second solid cold storage tank group 606, is used for circulating air supply; a control valve is provided on the pipeline connecting the second air supply tank 607 and the second solid cold storage tank group 606;

[0132] A third cold fluid three-way valve 608, wherein a first port of the third cold fluid three-way valve 608 is connected to an upper port of the second solid cold storage tank group 606;

[0133] A second circulation fan 609, the output end of the second circulation fan 609 is connected to the second port of the third cold fluid three-way valve 608, and the input end of the second circulation fan 609 is connected to the fourth output end C6 of the cold box 301 as the second input end of the second cold storage unit 600;

[0134] A fourth cold fluid three-way valve 610, a first port of the fourth cold fluid three-way valve 610 is connected to the lower port of the second solid cold storage tank group 606, a second port of the second cold fluid three-way valve 605 is connected to the fourth input end C5 of the cold box 301 as the second output end of the second cold storage unit 600, and a third port of the fourth cold fluid three-way valve 610 is connected to the first output end C8 of the LNG vaporization supply unit 900 as the fourth input end of the cold storage unit 600;

[0135] The third circulation fan 611, the input end of the third circulation fan 611 is connected to the first input end C7 of the LNG vaporization supply unit 900 as the fourth output end of the cold storage unit 600, and the output end of the third circulation fan 611 is connected to the third port of the third cold fluid three-way valve 608.

[0136] In the above embodiment, the first cold storage unit 600 and the second cold storage unit 600 can adopt a parallel solid cold storage tank group solution, or a series solid cold storage tank group solution. In the parallel solid cold storage tank group solution, the LNG vaporization cold energy is fully utilized in the cold box 301; while in the series solid cold storage tank group solution, the LNG vaporization cold energy is only utilized in a part of the temperature section in the cold box 301, and the high-grade low-temperature cold energy is provided by liquid air.

[0137] At the same time, no matter which form it is, the LNG vaporization cold energy should be transferred to the cold box 301 for use through valve control first, because the cold energy is lost in the cold storage unit. At this time, the cold energy from the cold storage unit 600 in the cold box 301 includes both LNG instant vaporization cold energy and cold energy stored in the solid cold storage tank; when the LNG vaporization cold energy cannot be used immediately, the solid cold storage tank is stored through valve control.

[0138] The circulating medium in the cold storage unit 600 may be nitrogen / air, methanol / propane, argon, etc., which is not limited in this embodiment.

[0139] Embodiment 2, in this embodiment, a liquid air energy storage method for improving cycle efficiency by utilizing LNG cold energy and combustion heat energy is provided, and this method is implemented based on the liquid air energy storage and liquefied natural gas coupled high-efficiency power generation device in embodiment 1. In this embodiment, the method includes an air liquefaction cycle process, an air power generation cycle process, an LNG vaporization supply process, and a high-grade thermal energy utilization process.

[0140] Air liquefaction cycle process: ambient air is pressurized and inter-stage cooled by the compressor unit 100, purified by the air purification unit 200, and then enters the cold box 301 for cooling, expansion, throttling, and separation of liquid, and then stored in the liquid air storage tank 401; the air compression heat is stored through the heat storage unit 700.

[0141] Air power generation cycle process: the liquid air output from the liquid air storage tank 401 is pressurized to high pressure by the first cryogenic liquid pump 402, enters the evaporator 403 to undergo a liquid-gas phase change process, and then enters the power generation expander 800 to generate power; the cold energy of the vaporization of the liquid air is stored in the cold storage unit 600.

[0142] LNG vaporization supply process: the liquefied natural gas output from the LNG storage tank 901 is pressurized by the second cryogenic liquid pump 902, enters the LNG vaporizer 903 for vaporization, and then delivers the natural gas to the user pipeline network. The waste natural gas naturally discharged from the LNG storage tank 901 is collected by the natural gas collection tank 904), thereby obtaining natural gas resources for free. At the same time, the cold energy of LNG vaporization is used in the cold box 301 to cooperate with the cold energy of liquid air vaporization to further cool the imported air, thereby obtaining a higher air liquefaction rate and system cycle efficiency.

[0143] High-grade thermal energy utilization process: The oil pump 802 promotes the circulation of the heat transfer oil, extracts the lower-grade thermal energy from the heat storage unit 700 through the oil-water heat exchanger 803, and then obtains the higher-grade thermal energy through the combustion of natural gas in the combustion chamber 804. The heat transfer oil circulation is used to transfer the high-quality thermal energy to the inlet air before the power generation expander, thereby obtaining higher expansion power generation power and system cycle efficiency.

[0144] Embodiment 3: In this embodiment, the effects of the application of the present invention are further described based on the above-mentioned embodiments 1 and 2. Figure 1 As shown, the liquid air energy storage and liquefied natural gas coupled high-efficiency power generation device in Example 1 uses a cold storage unit to store the low-temperature cold energy of liquefied natural gas and liquid air for liquefied air. The system performance parameters and design parameters are shown in Tables 1 and 2. The cycle efficiency of the coupled system can reach 64.9%, which is about 29.8% higher than that of the traditional independent liquid air energy storage system.

[0145] Table 1 System performance parameters

[0146] parameter Numeric parameter Numeric Compressor power consumption (MWh) 182.64 Cryogenic pump power consumption (MWh) 5.824 Liquid expander output power (MWh) 2.184 Expander output power (MWh) 130.4 Circulation fan 1 cooling power consumption (MWh) 1.104 Circulation fan 1 cooling power consumption (MWh) 1.86 Cooling power consumption of circulating fan 2 (MWh) 3.216 Circulation fan 2 cold storage power consumption (MWh) 4.359 Electric heating power consumption (MWh) 0 Liquefaction rate 86％ System cycle efficiency 64.9％ LNG inlet temperature(℃) -145 LNG outlet temperature (℃) 5.44 LNG mass flow rate (kg / s) 12.75 Liquid air output per kWh of electricity consumption (kg) 4.34 LNG cooling capacity (MWh) 68

[0147] Table 2 System design parameters

[0148]

[0149]

[0150] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A liquid air energy storage and liquefied natural gas coupled high-efficiency power generation device, characterized in that: include: Air liquefaction circulation loop, air power generation circulation loop, LNG vaporization supply loop and high-grade thermal energy utilization loop; The air liquefaction circulation loop is used to purify, compress and cool the ambient air, expand and reduce the pressure to obtain liquid air, and the liquid air is transmitted to the air power generation circulation loop, and the air compression heat generated during the compression process is stored in the heat storage unit (700); The air power generation cycle loop pressurizes, evaporates and further heats the received liquid air to expand and generate electricity, and the cold energy generated in the liquid air vaporization process is stored in the cold storage unit (600); The LNG vaporization supply loop supplies liquefied natural gas to the user side after pressurization, evaporation and gasification. The cold energy generated in the liquefied natural gas vaporization process is stored in the cold storage unit (600) or directly supplied to the air liquefaction circulation loop. At the same time, the gaseous natural gas naturally released by the LNG tank is effectively collected and transmitted to the combustion chamber (804) in the high-grade thermal energy utilization loop according to the use demand. The high-grade heat energy utilization loop is driven by a pump to circulate the heat transfer oil, first recovering the lower-grade heat energy of the heat storage unit (700), then recovering the high-grade natural gas combustion heat energy, and finally transferring the high-grade heat energy to the air power generation circulation loop. After the heat transfer oil releases all the heat energy, it returns to the initial state and continues to circulate.

2. The liquid air energy storage and liquefied natural gas coupled high-efficiency power generation device as claimed in claim 1, characterized in that: The air liquefaction circulation loop comprises a cold storage unit (600), a heat storage unit (700), an air compressor unit (100), an air purification unit (200), a cold box (301), a low-temperature expander (302), a low-temperature throttle valve (303), a gas-liquid separator (304) and a liquid air storage tank (401); the cold storage unit (600) is provided in two: a first cold storage unit (600) and a second cold storage unit (600); The first input end of the air compressor group (100) is used to input ambient air, and the first output end of the air compressor group (100) is connected to the first input end of the cold box (301); the second output end of the air compressor group (100) is connected to the first input end of the air purification unit (200), and the second input end of the air compressor group (100) is connected to the first output end of the air purification unit (200); the third input end of the air compressor group (100) is connected to the first output end of the heat storage unit (700), and the third output end of the air compressor group (100) is connected to the first input end of the heat storage unit (700), and the fourth input end of the air compressor group (100) is connected to the second output end of the cold box (301); The air purification unit (200) comprises a precooler (201) and a molecular sieve adsorption bed (202); a first output end of the cold box (301) is connected to an input end of a low-temperature expander (302), and a second input end of the cold box (301) is connected to a second output end of a gas-liquid separator (304); a third input end of the cold box (301) is connected to a first output end of a first cold storage unit (600), and a third output end of the cold box (301) is connected to a first input end of the first cold storage unit (600); a fourth input end of the cold box (301) is connected to a second output end of a second cold storage unit (600), and a fourth output end of the cold box (301) is connected to a second input end of the second cold storage unit (600); The output end of the low-temperature expander (302) is connected to the input end of the gas-liquid separator (304) via the low-temperature throttle valve (303), and the first output end of the gas-liquid separator (304) is connected to the liquid air storage tank (401).

3. The liquid air energy storage and liquefied natural gas coupled high-efficiency power generation device as claimed in claim 2, characterized in that: The first cold storage unit (600) is located at the lower side of the cold box (301); the second cold storage unit (600) is located at the lower side of the cold box (301), or is arranged at the upper side of the cold box (301); When the first cold storage unit (600) and the second cold storage unit (600) adopt a parallel structure, the second cold storage unit (600) is arranged on the upper side of the cold box (301), and the LNG cold energy is independently stored in the second cold storage unit (600); when the first cold storage unit (600) and the second cold storage unit (600) adopt a series structure, the second cold storage unit (600) is arranged on the lower side of the cold box (301), and the LNG cold energy is coupled with the cold energy of vaporization of a part of the temperature zone of the liquid air and stored in the second cold storage unit (600), and the first cold storage unit (600) and the second cold storage unit (600) form a series ladder temperature cold energy storage.

4. The liquid air energy storage and liquefied natural gas coupled high-efficiency power generation device as claimed in claim 1, characterized in that: The air power generation circulation loop comprises a cold storage unit (600), a liquid air storage tank (401), a first cryogenic liquid pump (402), an evaporator (403), a high-quality thermal energy utilization unit (800) and a power generation expansion unit (500); The input end of the first cryogenic liquid pump (402) is connected to the output end of the liquid air storage tank (401), and the output end of the first cryogenic liquid pump (402) is connected to the first input end of the evaporator (403); The first output end of the evaporator (403) is connected to the first input end of the power generation expansion unit (500), the second output end of the evaporator (403) is connected to the third input end of the first cold storage unit (600), and the second input end of the evaporator (403) is connected to the third output end of the first cold storage unit (600); The first output end of the power generation expansion unit (500) is connected to the external environment, the second input end of the power generation expansion unit (500) is connected to the first output end of the high-quality thermal energy utilization unit (800), and the second output end of the power generation expansion unit (500) is connected to the first input end of the high-quality thermal energy utilization unit (800).

5. The liquid air energy storage and liquefied natural gas coupled high-efficiency power generation device as claimed in claim 1, characterized in that: The LNG vaporization supply circuit is an LNG vaporization supply unit (900), comprising: The LNG storage tank (901) has a liquid outlet and an exhaust port; the liquid outlet is used to discharge liquefied natural gas to the outside; the exhaust port is used to maintain the pressure balance of the tank body, and the discharged gaseous natural gas is effectively collected and burned to obtain high-grade thermal energy for improving the work efficiency of the power generation expander; A second cryogenic liquid pump (902), wherein an input end of the second cryogenic liquid pump (902) is connected to a liquid outlet of the LNG storage tank (901); An LNG vaporizer (903), wherein a first input end of the LNG vaporizer (903) is connected to an output end of the second cryogenic liquid pump (902), and a first output end of the LNG vaporizer (903) is connected to a user side as a third output end of the LNG vaporization supply unit (900); a second input end of the LNG vaporizer (903) is connected to a fourth output end of the second cold storage unit (600) as a first input end of the LNG vaporization supply unit (900), and a second output end of the LNG vaporizer (903) is connected to a fourth input end of the second cold storage unit (600) as a first output end of the LNG vaporization supply unit (900); A natural gas collection tank (904), wherein the input end of the natural gas collection tank (904) is connected to the exhaust port of the LNG storage tank (901), and the output end of the natural gas collection tank (904) is connected to the third input end of the high-quality thermal energy utilization unit (800) as the second output end of the LNG vaporization supply unit (900).

6. The liquid air energy storage and liquefied natural gas coupled high-efficiency power generation device as claimed in claim 1, characterized in that: The heat storage unit (700) comprises: A normal temperature water tank (701) having an upper port and a lower port, wherein the lower port serves as a second input end of the heat storage unit (700) and is connected to a second output end of the high-quality thermal energy utilization unit (800); A first radiator (702), wherein an input end of the first radiator (702) is connected to an upper port of the normal temperature water tank (701); A first water pump (703), wherein an input end of the first water pump (703) is connected to an output end of the first radiator (703), and an output end of the first water pump (703) is connected to a third input end of the air compressor unit (100) as a first output end of the heat storage unit (700); A hot water tank (704) having an upper port and a lower port, wherein the upper port serves as a first input end of the heat storage unit (700) and is connected to a third output end of the air compressor unit (100); A second water pump (705), the input end of the second water pump (705) is connected to the lower port of the hot water tank (704), and the output end of the second water pump (705) is connected to the second input end of the high-quality thermal energy utilization unit (800) as the second output end of the heat storage unit (700).

7. The liquid air energy storage and liquefied natural gas coupled high-efficiency power generation device as claimed in claim 1, characterized in that: The high-grade heat energy utilization circuit is a high-grade heat energy utilization unit (800), comprising: The oil replenishment tank (801) is used to replenish the hot oil working medium to the circulation; An oil pump (802) is arranged on the oil outlet pipeline of the oil replenishment tank (801) and is used to provide power for the working medium circulation; An oil-water heat exchanger (803), wherein a first input end of the oil-water heat exchanger (803) is connected to an output end of the oil pump (802), a second input end of the oil-water heat exchanger (803) is connected to a second output end of the heat storage unit (700) as a second input end of the high-quality thermal energy utilization unit (800), and a second output end of the oil-water heat exchanger (803) is connected to a second input end of the heat storage unit (700) as a second output end of the high-quality thermal energy utilization unit (800); A combustion chamber (804), wherein a first input end of the combustion chamber (804) is connected to a second output end of the LNG vaporization supply unit (900) as a third input end of the high-quality thermal energy utilization unit (800), a first output end of the combustion chamber (804) is connected to an external environment as a third output end of the high-quality thermal energy utilization unit (800), a second input end of the combustion chamber (804) is connected to a first output end of an oil-water heat exchanger (803), and a second output end of the combustion chamber (804) is connected to a second input end of a power generation expansion unit (500) as a first output end of the high-quality thermal energy utilization unit (800); A second radiator (805), the input end of the second radiator (805) is connected to the second output end of the power generation expansion unit (500) as the first input end of the high-quality thermal energy utilization unit (800), and the output end of the second radiator (805) is connected to the input end of the oil pump (802).

8. The liquid air energy storage and liquefied natural gas coupled high-efficiency power generation device as claimed in claim 2, characterized in that: The first cold storage unit (600) comprises: A first solid cold storage tank group (601) having an upper port and a lower port; A first air replenishment tank (602), which is connected in parallel with the first solid cold storage tank group (601) and is used for circulating air replenishment; A first circulation fan (603), wherein an input end of the first circulation fan (603) is connected to an upper port of the first solid cold storage tank group (601); A first cold fluid three-way valve (604), wherein a first port of the first cold fluid three-way valve (604) is connected to an output end of a first circulation fan (603), a second port of the first cold fluid three-way valve (604) is connected to a third output end of a cold box (301) as a first input end of a cold storage unit (600), and a third port of the first cold fluid three-way valve (604) is connected to a second input end of an evaporator (403) as a third output end of a cold storage unit (600); A second cold fluid three-way valve (605), wherein a first port of the second cold fluid three-way valve (605) is connected to a lower port of the first solid cold storage tank group (601), a second port of the second cold fluid three-way valve (605) is connected to a third input end of the cold box (301) as a first output end of the cold storage unit (600), and a third port of the first cold fluid three-way valve (602) is connected to a second output end of the evaporator (403) as a third input end of the cold storage unit (600); The second cold storage unit (600) comprises: A second solid cold storage tank set (606) having an upper port and a lower port; A second air supply tank (607), which is connected in parallel with the second solid cold storage tank group (606) and is used for circulating air supply; A third cold fluid three-way valve (608), wherein a first port of the third cold fluid three-way valve (608) is connected to an upper port of the second solid cold storage tank group (606); A second circulation fan (609), the output end of the second circulation fan (609) is connected to the second port of the third cold fluid three-way valve (608), and the input end of the second circulation fan (609) is connected to the fourth output end of the cold box (301) as the second input end of the second cold storage unit (600); a fourth cold fluid three-way valve (610), wherein a first port of the fourth cold fluid three-way valve (610) is connected to a lower port of the second solid cold storage tank group (606), a second port of the second cold fluid three-way valve (605) is connected to a fourth input end of the cold box (301) as a second output end of the second cold storage unit (600), and a third port of the fourth cold fluid three-way valve (610) is connected to a first output end of the LNG vaporization supply unit (900) as a fourth input end of the cold storage unit (600); A third circulation fan (611), the input end of the third circulation fan (611) is connected to the first input end of the LNG vaporization supply unit (900) as the fourth output end of the cold storage unit (600), and the output end of the third circulation fan (611) is connected to the third port of the third cold fluid three-way valve (608).

9. The liquid air energy storage and liquefied natural gas coupled high-efficiency power generation device as claimed in claim 8, characterized in that: When the first cold storage unit (600) and the second cold storage unit (600) are connected in parallel, the LNG vaporization cold energy is fully utilized in the temperature range in the cold box (301); when they are connected in series, the LNG vaporization cold energy is only utilized in a part of the temperature range in the cold box (301), and high-quality low-temperature cold energy is provided by liquid air.

10. A liquid air energy storage method for improving cycle efficiency by utilizing LNG cold energy and combustion heat energy, based on the liquid air energy storage and liquefied natural gas coupled high-efficiency power generation device as claimed in any one of claims 1 to 9, characterized in that: include: Air liquefaction cycle process, air power generation cycle process, LNG vaporization supply process and high-grade thermal energy utilization process; Air liquefaction cycle process: ambient air is pressurized and inter-stage cooled by the compressor unit (100), purified by the air purification unit (200), and then enters the cold box (301) for cooling, expansion, throttling, and separation of liquid, and then stored in the liquid air storage tank (401); wherein the air compression heat is stored by the heat storage unit (700); Air power generation cycle process: the liquid air output from the liquid air storage tank (401) is pressurized to high pressure by the first cryogenic liquid pump (402), enters the evaporator (403) to undergo a liquid-gas phase change process, and then enters the power generation expander (800) to generate power; wherein the cold energy of the vaporized liquid air is stored by the cold storage unit (600); LNG vaporization supply process: the liquefied natural gas output from the LNG storage tank (901) is pressurized by the second cryogenic liquid pump (902), enters the LNG vaporizer (903) for vaporization, and then delivers the natural gas to the user pipeline network, wherein the waste natural gas naturally discharged from the LNG storage tank (901) is collected by the natural gas collection tank (904), and at the same time, the cold energy of LNG vaporization is used in the cold box (301) to cooperate with the cold energy of liquid air vaporization to further cool the inlet air, thereby obtaining a higher air liquefaction rate and system cycle efficiency; High-quality thermal energy utilization process: The oil pump (802) promotes the circulation of heat transfer oil, extracts lower-quality thermal energy from the heat storage unit (700) through the oil-water heat exchanger (803), and then obtains higher-quality thermal energy through the combustion of natural gas in the combustion chamber (804). The heat transfer oil circulation is used to transfer high-quality thermal energy to the front inlet air of the power generation expander, thereby obtaining higher expansion power generation power and system cycle efficiency.

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