Liquid air energy storage nitrogen and electric energy combined supply system and method

Abstract

The invention discloses a liquid air energy storage nitrogen and electric energy combined supply system and method, and belongs to the technical field of liquid air energy storage and air separation. The system comprises an air compression and purification unit, a cold box, a gas-liquid separator, a nitrogen preparation unit, a cold storage unit, a heat storage unit and an air expansion power generation unit; the air liquefaction circulation loop, the nitrogen preparation circulation loop and the air power generation circulation loop are formed, liquid air can be prepared in the electricity utilization trough period, nitrogen can be prepared by using the obtained liquid air in the level period and the peak period, and the electricity utilization cost of nitrogen preparation is remarkably reduced. Through electricity and gas combined supply, the system is more powerful in function, the double functions of power grid peak regulation and user gas supply can be achieved, the system economy is better, and application and popularization are convenient.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid air energy storage and air separation, and in particular to a liquid air energy storage nitrogen and electric energy combined supply system and method. Background Art

[0002] With the large-scale integration of fluctuating renewable energy sources such as wind power and photovoltaics, the power system faces severe peak load regulation pressure. Low-cost, long-duration energy storage technologies are urgently needed to enable energy transfer across time periods.

[0003] Liquid air energy storage (LAES) is considered one of the most promising large-scale energy storage technologies due to its unique advantages, including high energy storage density, unrestricted geographic location, long lifespan, and environmental friendliness. During periods of low electricity demand, electricity is used to drive a compressor to liquefy air, recovering the heat of compression as energy storage. During peak periods, the stored heat of compression is used to vaporize the liquid air and expand it to generate electricity, releasing energy. The core of LES is the conversion of "electricity → liquid air cooling / pressure energy → electricity" to complete the energy storage cycle.

[0004] Nitrogen, a key raw material in the chemical, electronics, and metallurgical industries, has an annual global demand exceeding 150 million tons. Traditional air separation nitrogen production relies on continuous electricity input, resulting in high energy consumption and poor responsiveness to electricity price fluctuations. Furthermore, evaporation losses during liquid nitrogen storage and transportation make nitrogen use expensive for small users. Summary of the Invention

[0005] In order to solve the above problems, the present invention provides a liquid air energy storage nitrogen and electric energy combined supply system and method.

[0006] To achieve the above object, the technical solutions adopted by the present invention are as follows:

[0007] A liquid air energy storage nitrogen and electric energy combined supply system comprises an air compression and purification unit, a cold box, a gas-liquid separator, a nitrogen production unit, a cold storage unit, an air expansion power generation unit, and a heat storage unit. The air compression and purification unit is used to compress air, and the compression heat generated during the air compression process is stored in the heat storage unit. The air compression and purification unit is connected to the gas-liquid separator via the cold box. The high-pressure air output by the air compression and purification unit enters the cold box for cooling and pressure reduction. The cooled and reduced-pressure air enters the gas-liquid separator and is separated into liquid air and gaseous air. The liquid air enters the air expansion power generation unit, undergoes pressurization and liquid-to-gas phase change, and the evaporation cold energy is stored in the cold storage unit. Part of the gaseous air returns to the cold box to release cold energy, and the other part enters the nitrogen production unit to prepare nitrogen, which is then supplied to users.

[0008] Furthermore, the first input end of the air compression and purification unit is used to input ambient air, the first output end of the air compression and purification unit is connected to the first input end of the cold box, the second output end of the air compression and purification unit is connected to the first input end of the heat storage unit, the second input end of the air compression and purification unit is connected to the first output end of the heat storage unit, the third input end of the air compression and purification unit is connected to the third output end of the cold box, and the fourth input end of the air compression and purification unit is connected to the fourth output end of the cold box;

[0009] The first output end of the cold box is connected to the input end of the gas-liquid separator, the second output end of the cold box is connected to the first input end of the cold storage unit, and the second input end of the cold box is connected to the first output end of the cold storage unit;

[0010] The first input end of the nitrogen production unit is connected to the second output end of the gas-liquid separator, the second input end of the nitrogen production unit is connected to the fifth output end of the cold box, the third input end of the nitrogen production unit is connected to the first output end of the air expansion power generation unit, the fourth input end of the nitrogen production unit is connected to the second output end of the air expansion power generation unit, the fifth input end of the nitrogen production unit is connected to the third output end of the air expansion power generation unit, the first output end of the nitrogen production unit is connected to the third input end of the cold box, the second output end of the nitrogen production unit is connected to the fourth input end of the cold box, and the third output end of the nitrogen production unit is connected to the second input end of the air expansion power generation unit;

[0011] The first input end of the air expansion power generation unit is connected to the first output end of the gas-liquid separator, the third input end of the air expansion power generation unit is connected to the second output end of the cold storage unit, the fourth input end of the air expansion power generation unit is connected to the second output end of the heat storage unit, the fourth output end of the air expansion power generation unit is connected to the second input end of the cold storage unit, and the fifth output end of the air expansion power generation unit is connected to the second input end of the heat storage unit.

[0012] Furthermore, the air compression purification unit includes:

[0013] a first compressor, wherein an input end of the first compressor serves as a first input end of an air compression and purification unit;

[0014] a first cooler, wherein a first input end of the first cooler is connected to an output end of the first compressor;

[0015] a second compressor, wherein an input end of the second compressor is connected to a first output end of the first cooler;

[0016] a second cooler, wherein a first input end of the second cooler is connected to an output end of the second compressor;

[0017] an air cooling tower, wherein a first input end of the air cooling tower is connected to a first output end of the second cooler;

[0018] a first water pump, wherein an input end of the first water pump is connected to a first output end of the air cooling tower;

[0019] an electric refrigerator, wherein the input end of the electric refrigerator is connected to the output end of the first water pump, and the output end of the electric refrigerator is connected to the second input end of the air cooling tower;

[0020] a water cooling tower, wherein a first input end of the water cooling tower is connected to an output end of the first water pump, and the first output end of the water cooling tower is discharged to the air;

[0021] a second water pump, wherein an input end of the second water pump is connected to a second output end of the water cooling tower, and an output end of the second water pump is connected to a third input end of the air cooling tower;

[0022] an adsorption tower, wherein an input end of the adsorption tower is connected to a second output end of the air cooling tower;

[0023] a first three-way valve, wherein a first port of the first three-way valve is connected to the output end of the adsorption tower, and a third port of the first three-way valve is connected to the third output end of the cold box as the third input end of the air compression purification unit;

[0024] a third compressor, wherein an input end of the third compressor is connected to the second port of the first three-way valve;

[0025] a third cooler, wherein a first input end of the third cooler is connected to an output end of the third compressor;

[0026] a fourth compressor, wherein an input end of the fourth compressor is connected to the first output end of the third cooler;

[0027] a fourth cooler, wherein a first input end of the fourth cooler is connected to an output end of the fourth compressor; a first output end of the fourth cooler, serving as a first output end of an air compression and purification unit, is connected to a first input end of a cold box;

[0028] The second input end of the first cooler, the second input end of the second cooler, the second input end of the third cooler, and the second input end of the fourth cooler are connected in parallel as the second input end of the air compression and purification unit, which is connected to the first output end of the heat storage unit; the second output end of the first cooler, the second output end of the second cooler, the second output end of the third cooler, and the second output end of the fourth cooler are connected in parallel as the second output end of the air compression and purification unit, which is connected to the first input end of the heat storage unit;

[0029] a second three-way valve, wherein a first port of the second three-way valve is connected to the second input end of the water cooling tower, and a third port of the second three-way valve is connected to the fourth output end of the cold box as the fourth input end of the air compression and purification unit;

[0030] A desorption tower, wherein the input end of the desorption tower is connected to the second port of the second three-way valve, and the output end of the desorption tower is discharged to the air.

[0031] Furthermore, the cold box includes:

[0032] An air cooler, wherein the first input end of the air cooler is connected to the first output end of the air compression and purification unit as the first input end of the cold box, the second input end of the air cooler is connected to the first output end of the cold storage unit as the second input end of the cold box, the third input end of the air cooler is connected to the first output end of the nitrogen production unit as the third input end of the cold box, the fourth input end of the air cooler is connected to the second output end of the nitrogen production unit as the fourth input end of the cold box, the second output end of the air cooler is connected to the first input end of the cold storage unit as the second output end of the cold box, the third output end of the air cooler is connected to the third input end of the air compression and purification unit as the third output end of the cold box, and the fourth output end of the air cooler is connected to the fourth input end of the air compression and purification unit as the fourth output end of the cold box;

[0033] a refrigeration expander, wherein the input end of the refrigeration expander is connected to the fifth output end of the air cooler, and the output end of the refrigeration expander is connected to the second input end of the nitrogen production unit as the fifth output end of the cold box;

[0034] A first throttle valve, wherein the input end of the first throttle valve is connected to the first output end of the air cooler, and the output end of the first throttle valve is connected to the input end of the gas-liquid separator as the first output end of the cold box.

[0035] Furthermore, the nitrogen production unit includes:

[0036] a third three-way valve, wherein the first port of the third three-way valve is supplied to the user, and the third port of the third three-way valve is connected to the second output end of the distillation tower;

[0037] a condenser evaporator, wherein a first input end of the condenser evaporator is connected to an output end of the second throttle valve, a second input end of the condenser evaporator is connected to a second port of the third three-way valve, and a second output end of the condenser evaporator is connected to a fourth input end of the cold box as a second output end of the nitrogen production unit;

[0038] a distillation tower, wherein a first input end of the distillation tower is connected to an output end of the second switch valve, a second input end of the distillation tower is connected to an output end of the first switch valve, a third input end of the distillation tower is connected to a first port of a sixth three-way valve, and a fourth input end of the distillation tower is connected to a first output end of a condenser evaporator;

[0039] a second throttle valve, wherein an input end of the second throttle valve is connected to a first output end of the distillation column;

[0040] a first switch valve, wherein an input end of the first switch valve is connected to a first port of the seventh three-way valve;

[0041] a liquid air pump, wherein the input end of the liquid air pump serves as the third input end of the nitrogen production unit and is connected to the first output end of the air expansion power generation unit, and the output end of the liquid air pump is connected to the second port of the seventh three-way valve;

[0042] a second on-off valve, wherein an input end of the second on-off valve is connected to the second port of the fifth three-way valve;

[0043] a third switch valve, wherein an input end of the third switch valve is connected to the third port of the fifth three-way valve;

[0044] a fourth three-way valve, wherein the first port of the fourth three-way valve is connected to the fifth output end of the cold box as the second input end of the nitrogen production unit, and the second port of the fourth three-way valve is connected to the third input end of the cold box as the first output end of the nitrogen production unit; and the third port of the fourth three-way valve is connected to the output end of the third switch valve;

[0045] a fifth three-way valve, wherein a first port of the fifth three-way valve serves as a first input end of the nitrogen production unit and is connected to the second output end of the gas-liquid separator;

[0046] a sixth three-way valve, wherein the second port of the sixth three-way valve is connected to the second output end of the air expansion power generation unit as the fourth input end of the nitrogen production unit, and the third port of the sixth three-way valve is connected to the third output end of the air expansion power generation unit as the fifth input end of the nitrogen production unit;

[0047] A seventh three-way valve, wherein the third port of the seventh three-way valve serves as the third output end of the nitrogen production unit and is connected to the second input end of the air expansion power generation unit.

[0048] Furthermore, the cold storage unit includes:

[0049] A cold storage packed bed having a left port and a right port

[0050] a first circulation fan, wherein an input end of the first circulation fan is connected to the second output end of the cold box as a first input end of the cold storage unit, and an output end of the first circulation fan is connected to a left port of the cold storage filled bed;

[0051] A second circulation fan, wherein the input end of the second circulation fan is connected to the left port of the cold storage filled bed, and the output end of the second circulation fan is connected to the third input end of the air expansion power generation unit as the second output end of the cold storage unit;

[0052] The fourth switch valve has an input end connected to the output end of the second circulation fan, and the fourth switch valve is opened only during the grid flat period and the grid peak period.

[0053] Furthermore, the air expansion power generation unit includes:

[0054] A liquid air storage tank, wherein an input end of the liquid air storage tank is connected to a first output end of the gas-liquid separator as a first input end of the air expansion power generation unit, and a second output end of the liquid air storage tank is connected to a third input end of the nitrogen production unit as a first output end of the air expansion power generation unit;

[0055] A cryogenic liquid pump, the input end of which is connected to the first output end of the liquid air storage tank

[0056] an evaporator, wherein a first input end of the evaporator is connected to an output end of a cryogenic liquid pump, a second input end of the evaporator is connected to a second output end of a cold storage unit as a third input end of an air expansion power generation unit, a third input end of the evaporator is connected to a third port of an eighth three-way valve, a fourth input end of the evaporator is connected to an output end of a sixth switch valve, a second output end of the evaporator is connected to a second input end of a cold storage unit as a fourth output end of an air expansion power generation unit, and a third output end of the evaporator is connected to a fourth input end of a nitrogen production unit as a second output end of the air expansion power generation unit;

[0057] a first heater, wherein a first input end of the first heater is connected to a first output end of the evaporator;

[0058] a first expansion generator, wherein an input end of the first expansion generator is connected to a first output end of the first heater;

[0059] A second heater, a first input end of the second heater is connected to an output end of the first expansion generator

[0060] a second expansion generator, wherein an input end of the second expansion generator is connected to the first output end of the second heater;

[0061] a third heater, wherein a first input end of the third heater is connected to an output end of the second expansion generator;

[0062] a third expansion generator, wherein an input end of the third expansion generator is connected to the first output end of the third heater;

[0063] a fourth heater, wherein a first input end of the fourth heater is connected to an output end of the third expansion generator;

[0064] a fourth expansion generator, wherein an input end of the fourth expansion generator is connected to the first port of the eighth three-way valve;

[0065] The second input end of the first heater, the second input end of the second heater, the second input end of the third heater, and the second input end of the fourth heater are connected in parallel as the fourth input end of the air expansion power generation unit, which is connected to the second output end of the heat storage unit; the second output end of the first heater, the second output end of the second heater, the second output end of the third heater, and the second output end of the fourth heater are connected in parallel as the fifth output end of the air expansion power generation unit, which is connected to the second input end of the heat storage unit;

[0066] an eighth three-way valve, wherein a second port of the eighth three-way valve is connected to the first output end of the fourth heater;

[0067] a fifth switch valve, wherein the input end of the fifth switch valve is connected to the fourth output end of the evaporator, and the output end of the fifth switch valve serves as the third output end of the air expansion power generation unit and is connected to the fifth input end of the nitrogen production unit;

[0068] A sixth switch valve, wherein the input end of the sixth switch valve serves as the second input end of the air expansion power generation unit and is connected to the third output end of the nitrogen production unit.

[0069] Furthermore, the heat storage unit includes:

[0070] A heat storage tank, wherein an input end of the heat storage tank serves as a first input end of the heat storage unit and is connected to a second output end of the air compression and purification unit;

[0071] a first circulating water pump, wherein the input end of the first circulating water pump is connected to the output end of the normal temperature storage tank, and the output end of the first circulating water pump serves as the first output end of the heat storage unit and is connected to the second input end of the air compression purification unit;

[0072] a second circulating water pump, wherein the input end of the second circulating water pump is connected to the output end of the heat storage tank, and the input and output ends of the second circulating water pump serve as the second output end of the heat storage unit and are connected to the fourth input end of the air expansion power generation unit;

[0073] A normal temperature storage tank, wherein the input end of the normal temperature storage tank serves as the second input end of the heat storage unit and is connected to the fifth output end of the air expansion power generation unit.

[0074] The present invention also provides a method for combining liquid air energy storage nitrogen and electric energy supply, which is implemented by using the above-mentioned liquid air energy storage nitrogen and electric energy combined supply system.

[0075] During off-peak hours of the power grid, the air liquefaction cycle and the nitrogen production cycle operate in conjunction. After air purification, it is compressed to obtain high-pressure air. After cooling, pressurization, and separation, liquid air and gaseous air are obtained. The liquid air is stored in the liquid air storage tank of the air expansion power generation unit; the gaseous air is passed through the nitrogen production unit to obtain nitrogen and liquid nitrogen.

[0076] During peak hours of the power grid, the air power generation loop and the nitrogen production loop operate in conjunction. The liquid air output from the liquid air storage tank is divided into two streams. One stream of liquid air undergoes pressurization and liquid-to-gas phase change to recover evaporative cooling energy, while the other stream of liquid air is passed through the nitrogen production unit to obtain nitrogen gas and liquid nitrogen.

[0077] During periods of grid flatness, the nitrogen production cycle operates to produce nitrogen gas and liquid nitrogen.

[0078] Furthermore, the air liquefaction circulation loop is as follows:

[0079] The first input end of the air compression and purification unit is used to input ambient air, the first output end of the air compression and purification unit is connected to the first input end of the cold box, the second output end of the air compression and purification unit is connected to the first input end of the heat storage unit, the second input end of the air compression and purification unit is connected to the first output end of the heat storage unit, the third input end of the air compression and purification unit is connected to the third output end of the cold box, and the fourth input end of the air compression and purification unit is connected to the fourth output end of the cold box;

[0080] The first output end of the cold box is connected to the input end of the gas-liquid separator, the second output end of the cold box is connected to the first input end of the cold storage unit, and the second input end of the cold box is connected to the first output end of the cold storage unit;

[0081] The nitrogen production cycle is as follows:

[0082] The first input end of the nitrogen production unit is connected to the second output end of the gas-liquid separator, the second input end of the nitrogen production unit is connected to the fifth output end of the cold box, the third input end of the nitrogen production unit is connected to the first output end of the air expansion power generation unit, the fourth input end of the nitrogen production unit is connected to the second output end of the air expansion power generation unit, the fifth input end of the nitrogen production unit is connected to the third output end of the air expansion power generation unit, the first output end of the nitrogen production unit is connected to the third input end of the cold box, the second output end of the nitrogen production unit is connected to the fourth input end of the cold box, and the third output end of the nitrogen production unit is connected to the second input end of the air expansion power generation unit;

[0083] The air power generation cycle is as follows:

[0084] The first input end of the air expansion power generation unit is connected to the first output end of the gas-liquid separator, the third input end of the air expansion power generation unit is connected to the second output end of the cold storage unit, the fourth input end of the air expansion power generation unit is connected to the second output end of the heat storage unit, the fourth output end of the air expansion power generation unit is connected to the second input end of the cold storage unit, and the fifth output end of the air expansion power generation unit is connected to the second input end of the heat storage unit.

[0085] Furthermore, during the off-peak period of the power grid, the air liquefaction cycle and the nitrogen production cycle are operated in conjunction: after two-stage compression and inter-stage cooling, the ambient air enters the air cooling tower for cooling, and then enters the adsorption tower to remove water, carbon dioxide, alkanes and other components in the air, and then is further compressed to high pressure by the third compressor and the fourth compressor. At the same time, the compression heat generated by the air compression process is recovered by the heat exchange fluid and stored in the heat storage unit; the high-pressure air output by the air compression and purification unit enters the air cooler, a part of the pre-cooled air passes through the refrigeration expander, and the other part continues to cool and throttle and reduce the pressure, and then enters the gas-liquid separator to separate the liquid air and gaseous air, where the liquid air is stored In the liquid air storage tank, the gaseous air is divided into two parts. One part merges with the cold air from the refrigeration expander and flows back to the air cooler to release the cold energy. It then enters the first three-way valve, and the other part directly enters the distillation tower. The air entering the distillation tower is separated, and oxygen-rich liquid air is obtained at the bottom of the distillation tower, and high-purity nitrogen is obtained at the top of the distillation tower. The oxygen-rich liquid air extracted from the bottom of the distillation tower undergoes a liquid-to-gas phase change in the condenser evaporator, then enters the air cooler for reheating and is subsequently divided into two parts. One part is used as regeneration gas for the desorption tower, and the other part is supplied to the water-cooled tower. The nitrogen at the top of the distillation tower is divided into two streams. One stream is directly supplied to users, and the other stream is cooled in the condenser evaporator to become liquid nitrogen and flows back to the distillation tower.

[0086] During peak hours of the power grid, the air power generation cycle and the nitrogen production cycle operate in conjunction: the liquid air output from the liquid air storage tank is divided into two streams. One stream is pressurized to high pressure by a cryogenic liquid pump and then enters the evaporator to undergo a liquid-to-gas phase change process. The evaporation cold energy is recovered and stored in the cold storage packed bed through a heat exchange fluid. The high-pressure air at the evaporator outlet undergoes three-stage expansion and interstage heating and is divided into two parts. One part returns to the evaporator and enters the distillation tower, while the other part continues to expand and generate power. The other part passes through a liquid air pump and directly enters the distillation tower. The air entering the distillation tower is separated, and oxygen-rich liquid air is obtained at the bottom of the distillation tower, and high-purity nitrogen is obtained at the top of the distillation tower. The oxygen-rich liquid air extracted from the bottom of the distillation tower undergoes a liquid-to-gas phase change in the condenser evaporator, then enters the air cooler to be reheated to room temperature and then discharged to the outside environment. The nitrogen at the top of the distillation tower is divided into two streams. One stream is directly supplied to users, and the other stream is cooled in the condenser evaporator to become liquid nitrogen and return to the distillation tower.

[0087] During the period of grid flatness, nitrogen production cycles: the liquid air output from the liquid air storage tank is divided into two parts after passing through the liquid air pump. One part directly enters the distillation tower, and the other part undergoes a liquid-gas phase change in the evaporator to become low-temperature gaseous air, and then enters the distillation tower. The air entering the distillation tower is separated, and oxygen-rich liquid air is obtained at the bottom of the distillation tower, and high-purity nitrogen is obtained at the top of the distillation tower; the oxygen-rich liquid air extracted from the bottom of the distillation tower undergoes a liquid-gas phase change in the condenser evaporator, and then enters the air cooler to be reheated to room temperature, and then discharged to the external environment. The nitrogen at the top of the distillation tower is divided into two streams, one is directly supplied to users, and the other is cooled in the condenser evaporator to become liquid nitrogen and reflux to the distillation tower.

[0088] Compared with the prior art, the present invention has the following technical advances:

[0089] The present invention forms an air liquefaction circulation loop, a nitrogen production circulation loop and an air power generation circulation loop through the mutual cooperation of an air compression and purification unit, a cold box, a gas-liquid separator, a nitrogen production unit, a cold storage unit, a heat storage unit and an air expansion and power generation unit. Liquid air can be produced during off-peak hours, and nitrogen can be produced from the obtained liquid air during level hours and peak hours, significantly reducing the electricity cost of nitrogen production. Moreover, through the combined power supply, the system function is made more powerful, and the dual functions of grid peak regulation and user gas supply can be realized. BRIEF DESCRIPTION OF THE DRAWINGS

[0090] The accompanying drawings are used to provide further understanding of the present invention and constitute a part of the specification. They are used to explain the present invention together with the embodiments of the present invention and do not constitute a limitation of the present invention.

[0091] In the attached figure:

[0092] Figure 1A schematic structural diagram of a liquid air energy storage nitrogen and electricity combined supply system provided in an embodiment of the present invention;

[0093] In the picture:

[0094] 100. Air compression and purification unit, 101. First compressor, 102. First cooler, 103. Second compressor, 104. Second cooler, 105. Air cooling tower, 106. First water pump, 107. Electric refrigerator, 108. Water cooling tower, 109. Second water pump, 110. Adsorption tower, 111. First three-way valve, 112. Third compressor, 113. Third cooler, 114. Fourth compressor, 115. Fourth cooler, 116. Second three-way valve, 117. Desorption tower;

[0095] 200, cold box, 201, air cooler, 202, refrigeration expander, 203, first throttle valve; 300, gas-liquid separator;

[0096] 400, nitrogen production unit, 401, third three-way valve, 402, condenser evaporator, 403, distillation column, 404, second throttle valve, 405, first on-off valve, 406, liquid air pump, 407, second on-off valve, 408, third on-off valve, 409, fourth three-way valve, 410, fifth three-way valve, 411, sixth three-way valve, 412, seventh three-way valve;

[0097] 500, cold storage unit, 501, cold storage packed bed, 502, first circulation fan, 503, second circulation fan, 504, fourth switch valve;

[0098] 600, air expansion power generation unit, 601, liquid air storage tank, 602, cryogenic liquid pump, 603, evaporator, 604, first heater, 605, first expansion generator, 606, second heater, 607, second expansion generator, 608, third heater, 609, third expansion generator, 610, fourth heater, 611, fourth expansion generator, 612, eighth three-way valve, 613, fifth on-off valve, 614, sixth on-off valve;

[0099] 700. Heat storage unit, 701. Heat storage tank, 702. First circulating water pump, 703. Second circulating water pump, 704. Normal temperature storage tank. DETAILED DESCRIPTION

[0100] The following specific embodiments can be combined with each other, and the same or similar concepts or processes may not be described in detail in some embodiments. The embodiments of the present invention will be described below with reference to the accompanying drawings.

[0101] like Figure 1As shown, an embodiment of the present invention provides a liquid air energy storage nitrogen and electric energy combined supply system, including an air compression and purification unit 100, a cold box 200, a gas-liquid separator 300, a nitrogen production unit 400, a cold storage unit 500, an air expansion power generation unit 600 and a heat storage unit 700. The air compression and purification unit 100 is used to compress air, and the compression heat generated during the air compression process is stored in the heat storage unit 700; the air compression and purification unit 100 is connected to the gas-liquid separator 300 through the cold box 200. The high-pressure air output by the air compression and purification unit 100 enters the cold box 200 for cooling and pressure reduction. The cooled and depressurized air enters the gas-liquid separator 300 and is separated into liquid air and gaseous air. The liquid air enters the air expansion power generation unit 600, undergoes pressurization and liquid-gas phase change, and the evaporative cold energy is stored in the cold storage unit 500; part of the gaseous air returns to the cold box 200 to release cold energy, and the other part enters the nitrogen production unit 400 to prepare nitrogen, which is supplied to users.

[0102] The above 7 units are interconnected to form an air liquefaction circulation loop, a nitrogen production circulation loop and an air power generation circulation loop;

[0103] The air liquefaction circulation loop is composed of an air compression and purification unit 100, a cold box 200, a gas-liquid separator 300, a cold storage unit 500, and a heat storage unit 700. The connection relationship between the units is as follows:

[0104] The first input end of the air compression and purification unit 100 is used to input ambient air, the first output end of the air compression and purification unit 100 is connected to the first input end of the cold box 200, the second output end of the air compression and purification unit 100 is connected to the first input end of the heat storage unit 700, the second input end of the air compression and purification unit 100 is connected to the first output end of the heat storage unit 700, the third input end of the air compression and purification unit 100 is connected to the third output end of the cold box 200, and the fourth input end of the air compression and purification unit 100 is connected to the fourth output end of the cold box 200;

[0105] The first output end of the cold box 200 is connected to the input end of the gas-liquid separator 300, the second output end of the cold box 200 is connected to the first input end of the cold storage unit 500, and the second input end of the cold box 200 is connected to the first output end of the cold storage unit 500;

[0106] The nitrogen production cycle is formed by connecting the cold box 200, the gas-liquid separator 300, the nitrogen production unit 400 and the air expansion power generation unit 600. The connection relationship between the units is as follows:

[0107] The first input end of the nitrogen production unit 400 is connected to the second output end of the gas-liquid separator 300, the second input end of the nitrogen production unit 400 is connected to the fifth output end of the cold box 200, the third input end of the nitrogen production unit 400 is connected to the first output end of the air expansion power generation unit 600, the fourth input end of the nitrogen production unit 400 is connected to the second output end of the air expansion power generation unit 600, the fifth input end of the nitrogen production unit 400 is connected to the third output end of the air expansion power generation unit 600, the first output end of the nitrogen production unit 400 is connected to the third input end of the cold box 200, the second output end of the nitrogen production unit 400 is connected to the fourth input end of the cold box 200, and the third output end of the nitrogen production unit 400 is connected to the second input end of the air expansion power generation unit 600;

[0108] The air power generation cycle is composed of a gas-liquid separator 300, a nitrogen production unit 400, a cold storage unit 500, a heat storage unit 700 and an air expansion power generation unit 600. The connection relationship between the units is as follows:

[0109] The first input end of the air expansion power generation unit 600 is connected to the first output end of the gas-liquid separator 300, the third input end of the air expansion power generation unit 600 is connected to the second output end of the cold storage unit 500, the fourth input end of the air expansion power generation unit 600 is connected to the second output end of the heat storage unit 700, the fourth output end of the air expansion power generation unit 600 is connected to the second input end of the cold storage unit 500, and the fifth output end of the air expansion power generation unit 600 is connected to the second input end of the heat storage unit 700.

[0110] In specific design, the air compression and purification unit 100 includes:

[0111] A first compressor 101, wherein an input end of the first compressor 101 serves as a first input end of the air compression and purification unit 100;

[0112] A first cooler 102, wherein a first input end of the first cooler 102 is connected to an output end of the first compressor 101;

[0113] a second compressor 103 , wherein an input end of the second compressor 103 is connected to a first output end of the first cooler 102 ;

[0114] a second cooler 104 , wherein a first input end of the second cooler 104 is connected to an output end of the second compressor 103 ;

[0115] an air cooling tower 105 , wherein a first input end of the air cooling tower 105 is connected to a first output end of the second cooler 104 ;

[0116] a first water pump 106 , wherein an input end of the first water pump 106 is connected to a first output end of the air cooling tower 105 ;

[0117] An electric refrigerator 107, wherein the input end of the electric refrigerator 107 is connected to the output end of the first water pump 106, and the output end of the electric refrigerator 107 is connected to the second input end of the air cooling tower 105;

[0118] a water cooling tower 108 , wherein a first input end of the water cooling tower 108 is connected to an output end of the first water pump 106 , and a first output end of the water cooling tower 108 is discharged to the air;

[0119] a second water pump 109 , wherein the input end of the second water pump 109 is connected to the second output end of the water cooling tower 108 , and the output end of the second water pump 109 is connected to the third input end of the air cooling tower 105 ;

[0120] an adsorption tower 110 , wherein the input end of the adsorption tower 110 is connected to the second output end of the air cooling tower 105 ;

[0121] A first three-way valve 111, wherein a first port of the first three-way valve 111 is connected to the output end of the adsorption tower 110, and a third port of the first three-way valve 111 is connected to the third output end of the cold box 200 as the third input end of the air compression and purification unit 100;

[0122] a third compressor 112 , wherein an input end of the third compressor 112 is connected to a second port of the first three-way valve 111 ;

[0123] A third cooler 113, wherein a first input end of the third cooler 113 is connected to an output end of the third compressor 112;

[0124] a fourth compressor 114 , wherein an input end of the fourth compressor 114 is connected to a first output end of the third cooler 113 ;

[0125] A fourth cooler 115, wherein a first input end of the fourth cooler 115 is connected to an output end of the fourth compressor 114; a first output end of the fourth cooler 108, serving as a first output end of the air compression and purification unit 100, is connected to a first input end of the cold box 200;

[0126] 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 113, and the second input end of the fourth cooler 115 are connected in parallel as the second input end of the air compression and purification unit 100, which is connected to the first output end of the heat storage unit 700; the second output end of the first cooler 102, the second output end of the second cooler 104, the second output end of the third cooler 106, and the second output end of the fourth cooler 108 are connected in parallel as the second output end of the air compression and purification unit 100, which is connected to the first input end of the heat storage unit 700;

[0127] a second three-way valve 116, wherein a first port of the second three-way valve 116 is connected to a second input end of the water cooling tower 108, and a third port of the second three-way valve 116 is connected to a fourth output end of the cold box 200 as a fourth input end of the air compression and purification unit 100;

[0128] The desorption tower 117 has an input end connected to the second port of the second three-way valve 116 , and an output end of the desorption tower 117 is discharged to the air.

[0129] Specifically, the cold box 200 includes:

[0130] An air cooler 201, wherein a first input end of the air cooler 201 is connected to a first output end of the air compression and purification unit 100 as a first input end of the cold box 200, a second input end of the air cooler 201 is connected to a first output end of the cold storage unit 500 as a second input end of the cold box 200, a third input end of the air cooler 201 is connected to a first output end of the nitrogen production unit 400 as a third input end of the cold box 200, a fourth input end of the air cooler 201 is connected to a second output end of the nitrogen production unit 400 as a fourth input end of the cold box 200, a second output end of the air cooler 201 is connected to a first input end of the cold storage unit 500 as a second output end of the cold box 200, a third output end of the air cooler 201 is connected to a third input end of the air compression and purification unit 100 as a third output end of the cold box 200, and a fourth output end of the air cooler 201 is connected to a fourth input end of the air compression and purification unit 100 as a fourth output end of the cold box 200;

[0131] A refrigeration expander 202, wherein the input end of the refrigeration expander 202 is connected to the fifth output end of the air cooler 201, and the output end of the refrigeration expander 202 is connected to the second input end of the nitrogen production unit 400 as the fifth output end of the cold box 200;

[0132] The first throttle valve 203 has an input end connected to a first output end of the air cooler 201 , and an output end of the first throttle valve 203 is connected to an input end of the gas-liquid separator 300 as a first output end of the cold box 200 .

[0133] Specifically, the nitrogen production unit 400 includes:

[0134] A third three-way valve 401 , wherein a first port of the third three-way valve 401 is supplied to the user, and a third port of the third three-way valve 401 is connected to the second output end of the distillation tower 403 ;

[0135] A condenser evaporator 402, wherein a first input end of the condenser evaporator 402 is connected to an output end of the second throttle valve 404, a second input end of the condenser evaporator 402 is connected to a second port of the third three-way valve 401, and a second output end of the condenser evaporator 402 is connected to a fourth input end of the cold box 200 as a second output end of the nitrogen production unit 400;

[0136] a distillation tower 403, wherein a first input end of the distillation tower 403 is connected to an output end of a second on-off valve 407, a second input end of the distillation tower 403 is connected to an output end of a first on-off valve 405, a third input end of the distillation tower 403 is connected to a first port of a sixth three-way valve 411, and a fourth input end of the distillation tower 403 is connected to a first output end of a condenser evaporator 402;

[0137] a second throttle valve 404 , wherein an input end of the second throttle valve 404 is connected to a first output end of the distillation column 403 ;

[0138] a first switch valve 405 , wherein an input end of the first switch valve 405 is connected to a first port of the seventh three-way valve 412 ;

[0139] a liquid air pump 406, wherein the input end of the liquid air pump 406 is connected to the first output end of the air expansion power generation unit 600 as the third input end of the nitrogen production unit 400, and the output end of the liquid air pump 406 is connected to the second port of the seventh three-way valve 412;

[0140] a second switch valve 407 , wherein an input end of the second switch valve 407 is connected to a second port of the fifth three-way valve 410 ;

[0141] a third switch valve 408 , wherein an input end of the third switch valve 408 is connected to a third port of the fifth three-way valve 410 ;

[0142] A fourth three-way valve 409, wherein a first port of the fourth three-way valve 409 is connected to the fifth output end of the cold box 200 as the second input end of the nitrogen production unit 400, and a second port of the fourth three-way valve 409 is connected to the third input end of the cold box 200 as the first output end of the nitrogen production unit 400; and a third port of the fourth three-way valve 409 is connected to the output end of the third on-off valve 408;

[0143] a fifth three-way valve 410 , wherein a first port of the fifth three-way valve 410 serves as a first input end of the nitrogen production unit 400 and is connected to a second output end of the gas-liquid separator 300 ;

[0144] a sixth three-way valve 411, wherein a second port of the sixth three-way valve 411 is connected to the second output end of the air expansion power generation unit 600 as the fourth input end of the nitrogen production unit 400, and a third port of the sixth three-way valve 411 is connected to the third output end of the air expansion power generation unit 600 as the fifth input end of the nitrogen production unit 400;

[0145] The seventh three-way valve 412 has a third port serving as the third output end of the nitrogen production unit 400 connected to the second input end of the air expansion power generation unit 600 .

[0146] Specifically, the cold storage unit 500 includes:

[0147] Cold storage packed bed 501, which has a left port and a right port

[0148] A first circulation fan 502, wherein the input end of the first circulation fan 502 is connected to the second output end of the cold box 200 as the first input end of the cold storage unit 500, and the output end of the first circulation fan 502 is connected to the left port of the cold storage filled bed 501;

[0149] A second circulation fan 503, wherein the input end of the second circulation fan 503 is connected to the left port of the cold storage filled bed 501, and the output end of the second circulation fan 503 is connected to the third input end of the air expansion power generation unit 600 as the second output end of the cold storage unit 500;

[0150] The fourth switch valve 504 has its input end connected to the output end of the second circulation fan 503 , and the fourth switch valve 504 is only opened during the grid flat period and the grid peak period.

[0151] Specifically, the air expansion power generation unit 600 includes:

[0152] A liquid air storage tank 601, wherein an input end of the liquid air storage tank 601 is connected to a first output end of the gas-liquid separator 300 as a first input end of the air expansion power generation unit 600, and a second output end of the liquid air storage tank 601 is connected to a third input end of the nitrogen production unit 400 as a first output end of the air expansion power generation unit 600;

[0153] A cryogenic liquid pump 602, the input end of which is connected to the first output end of the liquid air storage tank 601

[0154] an evaporator 603, wherein a first input end of the evaporator 603 is connected to an output end of the cryogenic liquid pump 602, a second input end of the evaporator 603 is connected to a second output end of the cold storage unit 500 as a third input end of the air expansion power generation unit 600, a third input end of the evaporator 603 is connected to a third port of an eighth three-way valve 612, a fourth input end of the evaporator 603 is connected to an output end of a sixth on-off valve 614, a second output end of the evaporator 603 is connected to a second input end of the cold storage unit 500 as a fourth output end of the air expansion power generation unit 600, and a third output end of the evaporator 603 is connected to a fourth input end of the nitrogen production unit 400 as a second output end of the air expansion power generation unit 600;

[0155] a first heater 604 , wherein a first input end of the first heater 604 is connected to a first output end of the evaporator 603 ;

[0156] a first expansion generator 605 , wherein an input end of the first expansion generator 605 is connected to a first output end of the first heater 604 ;

[0157] The second heater 606 has a first input end connected to the output end of the first expansion generator 605.

[0158] a second expansion generator 607 , wherein an input end of the second expansion generator 607 is connected to a first output end of the second heater 606 ;

[0159] a third heater 608 , wherein a first input end of the third heater 608 is connected to an output end of the second expansion generator 607 ;

[0160] a third expansion generator 609 , wherein an input end of the third expansion generator 609 is connected to a first output end of the third heater 608 ;

[0161] a fourth heater 610 , wherein a first input end of the fourth heater 610 is connected to an output end of the third expansion generator 609 ;

[0162] a fourth expansion generator 611 , wherein an input end of the fourth expansion generator 611 is connected to a first port of an eighth three-way valve 612 ;

[0163] The second input end of the first heater 604, the second input end of the second heater 606, the second input end of the third heater 608, and the second input end of the fourth heater 610 are connected in parallel as the fourth input end of the air expansion power generation unit 600, which is connected to the second output end of the heat storage unit 700; the second output end of the first heater 604, the second output end of the second heater 606, the second output end of the third heater 608, and the second output end of the fourth heater 610 are connected in parallel as the fifth output end of the air expansion power generation unit 600, which is connected to the second input end of the heat storage unit 700;

[0164] an eighth three-way valve 612 , wherein a second port of the eighth three-way valve 612 is connected to the first output end of the fourth heater 610 ;

[0165] a fifth switch valve 613, wherein the input end of the fifth switch valve 613 is connected to the fourth output end of the evaporator 603, and the output end of the fifth switch valve 613, serving as the third output end of the air expansion power generation unit 600, is connected to the fifth input end of the nitrogen production unit 400;

[0166] The sixth switch valve 614 has an input end serving as the second input end of the air expansion power generation unit 600 connected to the third output end of the nitrogen production unit 400 .

[0167] Specifically, the heat storage unit 700 includes:

[0168] A heat storage tank 701, wherein the input end of the heat storage tank 701 serves as the first input end of the heat storage unit 700 and is connected to the second output end of the air compression and purification unit 100;

[0169] A first circulating water pump 702, wherein the input end of the first circulating water pump 702 is connected to the output end of the normal temperature storage tank 704, and the output end of the first circulating water pump 702 serves as the first output end of the heat storage unit 700 and is connected to the second input end of the air compression and purification unit 100;

[0170] A second circulating water pump 703, wherein the input end of the second circulating water pump 703 is connected to the output end of the heat storage tank 701, and the input and output ends of the second circulating water pump 703 serve as the second output end of the heat storage unit 700 and are connected to the fourth input end of the air expansion power generation unit 600;

[0171] The normal temperature storage tank 704 has an input end serving as the second input end of the heat storage unit 700 connected to the fifth output end of the air expansion power generation unit 600 .

[0172] The present invention also provides a method for combining liquid air energy storage nitrogen and electric energy supply, which is implemented by using the above-mentioned liquid air energy storage nitrogen and electric energy combined supply system.

[0173] During the off-peak period of the power grid, the air liquefaction cycle and the nitrogen production cycle are operated in conjunction: after two-stage compression and inter-stage cooling, the ambient air enters the air cooling tower 105 for cooling, and then enters the adsorption tower 110 to remove water, carbon dioxide, alkanes and other components in the air, and then is further compressed to high pressure by the third compressor 112 and the fourth compressor 114. At the same time, the compression heat generated by the air compression process is recovered by the heat exchange fluid and stored in the heat storage unit 700; the high-pressure air output by the air compression and purification unit 100 enters the air cooler 201, a part of the pre-cooled air passes through the refrigeration expander 202, and the other part continues to cool and throttle and reduce the pressure, and then enters the gas-liquid separator 300 to separate liquid air and gaseous air, of which the liquid air is stored in the liquid air storage tank 601 and the gaseous air is stored in the gas storage tank 601. The air is divided into two parts. One part merges with the cold air from the refrigeration expander 202 and then flows back to the air cooler 201 to release the cold energy. It then enters the first three-way valve 111, and the other part directly enters the distillation tower 403. The air entering the distillation tower 403 is separated, and oxygen-rich liquid air is obtained at the bottom of the distillation tower 403, and high-purity nitrogen is obtained at the top of the distillation tower 403. The oxygen-rich liquid air extracted from the bottom of the distillation tower 403 undergoes a liquid-to-gas phase transition in the condenser evaporator 402, then enters the air cooler 201 for reheating, and is then divided into two parts. One part is used as regeneration gas for the desorption tower 117, and the other part is supplied to the water-cooling tower 108. The nitrogen at the top of the distillation tower 403 is divided into two streams. One stream is directly supplied to users, and the other stream is cooled in the condenser evaporator 402 to become liquid nitrogen and flows back to the distillation tower 403.

[0174] During the peak hours of the power grid, the air power generation cycle and the nitrogen production cycle are operated in conjunction: the liquid air output from the liquid air storage tank 601 is divided into two streams. One stream is pressurized to high pressure by the cryogenic liquid pump 602, and then enters the evaporator 603 to undergo a liquid-gas phase change process, and the evaporation cold energy is recovered and stored in the cold storage packed bed 501 through the heat exchange fluid. The high-pressure air at the outlet of the evaporator 603 is divided into two parts after three-stage expansion and inter-stage heating. One part flows back to the evaporator 603 and enters the distillation tower 403, and the other part continues to expand to generate power; the other part is After passing through liquid air pump 406, it directly enters distillation tower 403. The air entering distillation tower 403 is separated, and oxygen-enriched liquid air is obtained at the bottom of distillation tower 403, and high-purity nitrogen is obtained at the top of distillation tower 403. The oxygen-enriched liquid air extracted from the bottom of distillation tower 403 undergoes a liquid-to-gas phase transition in condenser evaporator 402, then enters air cooler 201 to be reheated to room temperature and subsequently discharged to the external environment. The nitrogen at the top of distillation tower 403 is divided into two streams, one of which is directly supplied to users, and the other is cooled in condenser evaporator 102 to become liquid nitrogen and reflux to distillation tower 403.

[0175] During periods of grid flatness, nitrogen production operates in a cycle: the liquid air output from the liquid air storage tank 601 passes through the liquid air pump 602 and is divided into two parts. One part directly enters the distillation tower 403, and the other part undergoes a liquid-to-gas phase change in the evaporator 603 to become low-temperature gaseous air, which then enters the distillation tower 403. The air entering the distillation tower 403 is separated, and oxygen-rich liquid air is obtained at the bottom of the distillation tower 403, and high-purity nitrogen is obtained at the top of the distillation tower 403. The oxygen-rich liquid air extracted from the bottom of the distillation tower 403 undergoes a liquid-to-gas phase change in the condenser evaporator 402, then enters the air cooler 201 to be reheated to room temperature, and then discharged to the external environment. The nitrogen at the top of the distillation tower 403 is divided into two streams. One stream is directly supplied to users, and the other stream is cooled in the condenser evaporator 402 to become liquid nitrogen and refluxes to the distillation tower 403.

[0176] During the off-peak period of the power grid, the first switch valve 405, the second switch valve 407 and the third switch valve 408 are opened, and the first circulation fan 502 serves as the driving force for the gas in the cold storage packed bed, using the heat exchange fluid to release cold energy;

[0177] During the peak hours of the power grid, the first on-off valve 405 and the fourth on-off valve 504 are opened, and the second circulating fan 503 acts as the driving force for the gas in the cold storage packed bed, using the heat exchange fluid to recover the cold energy from the evaporation process of the liquid air and the reheating process of the oxygen-rich liquid air and store it in the cold storage packed bed 501;

[0178] During the grid flat period, the first switch valve 405, the fourth switch valve 504, the fifth switch valve 613 and the sixth switch valve 614 are opened, and the second circulation fan 503 serves as the driving force for the gas in the cold storage packed bed, using the heat exchange fluid to recover the cold energy of the liquid air evaporation process and the oxygen-rich liquid air reheating process and store it in the cold storage packed bed 501.

[0179] In summary, the present invention produces liquid air during off-peak hours and uses the obtained liquid air to produce nitrogen during level and peak hours, thereby significantly reducing the electricity cost of nitrogen production. Furthermore, through combined power supply, the system function is made more powerful, and the dual functions of grid peak regulation and user gas supply can be achieved, resulting in better system economy.

[0180] Finally, it should be noted that the above descriptions are merely preferred embodiments of the present invention and are not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art will be able to modify the technical solutions described in the aforementioned embodiments or substitute equivalents for some of the technical features. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention shall be included within the scope of protection of the claims of the present invention.

Claims

1. A liquid air energy storage nitrogen and electricity combined supply system, characterized by: The invention comprises an air compression and purification unit (100), a cold box (200), a gas-liquid separator (300), a nitrogen production unit (400), a cold storage unit (500), an air expansion power generation unit (600), and a heat storage unit (700). The air compression and purification unit (100) is used to compress air, and compression heat generated during the air compression process is stored in the heat storage unit (700). The air compression and purification unit (100) is connected to the gas-liquid separator (300) through the cold box (200). The high-pressure air output by the air compression and purification unit (100) enters the cold box (200) for cooling and reducing pressure. The cooled and reduced-pressure air enters the gas-liquid separator (300) to be separated into liquid air and gaseous air. The liquid air enters the air expansion power generation unit (600) and undergoes pressurization and liquid-gas phase change to store the evaporative cold energy in the cold storage unit (500). A part of the gaseous air returns to the cold box (200) to release cold energy, and the other part enters the nitrogen production unit (400) to prepare nitrogen, which is supplied to users.

2. The liquid air energy storage nitrogen and electricity combined supply system according to claim 1, characterized in that: The first input end of the air compression and purification unit (100) is used to input ambient air, the first output end of the air compression and purification unit (100) is connected to the first input end of the cold box (200), the second output end of the air compression and purification unit (100) is connected to the first input end of the heat storage unit (700), the second input end of the air compression and purification unit (100) is connected to the first output end of the heat storage unit (700), the third input end of the air compression and purification unit (100) is connected to the third output end of the cold box (200), and the fourth input end of the air compression and purification unit (100) is connected to the fourth output end of the cold box (200); The first output end of the cold box (200) is connected to the input end of the gas-liquid separator (300), the second output end of the cold box (200) is connected to the first input end of the cold storage unit (500), and the second input end of the cold box (200) is connected to the first output end of the cold storage unit (500); The first input end of the nitrogen production unit (400) is connected to the second output end of the gas-liquid separator (300), the second input end of the nitrogen production unit (400) is connected to the fifth output end of the cold box (200), the third input end of the nitrogen production unit (400) is connected to the first output end of the air expansion power generation unit (600), the fourth input end of the nitrogen production unit (400) is connected to the second output end of the air expansion power generation unit (600), the fifth input end of the nitrogen production unit (400) is connected to the third output end of the air expansion power generation unit (600), the first output end of the nitrogen production unit (400) is connected to the third input end of the cold box (200), the second output end of the nitrogen production unit (400) is connected to the fourth input end of the cold box (200), and the third output end of the nitrogen production unit (400) is connected to the second input end of the air expansion power generation unit (600); The first input end of the air expansion power generation unit (600) is connected to the first output end of the gas-liquid separator (300), the third input end of the air expansion power generation unit (600) is connected to the second output end of the cold storage unit (500), the fourth input end of the air expansion power generation unit (600) is connected to the second output end of the heat storage unit (700), the fourth output end of the air expansion power generation unit (600) is connected to the second input end of the cold storage unit (500), and the fifth output end of the air expansion power generation unit (600) is connected to the second input end of the heat storage unit (700).

3. The liquid air energy storage nitrogen and electricity combined supply system according to claim 2, characterized in that: The air compression and purification unit (100) comprises: a first compressor (101), wherein an input end of the first compressor (101) serves as a first input end of the air compression and purification unit (100); a first cooler (102), wherein a first input end of the first cooler (102) is connected to an output end of the first compressor (101); a second compressor (103), wherein an input end of the second compressor (103) is connected to a first output end of the first cooler (102); a second cooler (104), wherein a first input end of the second cooler (104) is connected to an output end of the second compressor (103); an air cooling tower (105), wherein a first input end of the air cooling tower (105) is connected to a first output end of the second cooler (104); a first water pump (106), wherein an input end of the first water pump (106) is connected to a first output end of the air cooling tower (105); An electric refrigerator (107), wherein the input end of the electric refrigerator (107) is connected to the output end of the first water pump (106), and the output end of the electric refrigerator (107) is connected to the second input end of the air cooling tower (105); a water cooling tower (108), wherein a first input end of the water cooling tower (108) is connected to an output end of the first water pump (106), and the first output end of the water cooling tower (108) is discharged to the air; a second water pump (109), wherein the input end of the second water pump (109) is connected to the second output end of the water cooling tower (108), and the output end of the second water pump (109) is connected to the third input end of the air cooling tower (105); an adsorption tower (110), wherein an input end of the adsorption tower (110) is connected to a second output end of the air cooling tower (105); a first three-way valve (111), wherein a first port of the first three-way valve (111) is connected to an output end of the adsorption tower (110), and a third port of the first three-way valve (111) is connected to a third output end of the cold box (200) as a third input end of the air compression purification unit (100); a third compressor (112), wherein an input end of the third compressor (112) is connected to a second port of the first three-way valve (111); a third cooler (113), wherein a first input end of the third cooler (113) is connected to an output end of the third compressor (112); a fourth compressor (114), wherein an input end of the fourth compressor (114) is connected to a first output end of the third cooler (113); a fourth cooler (115), wherein a first input end of the fourth cooler (115) is connected to an output end of the fourth compressor (114); a first output end of the fourth cooler (108) is connected to a first input end of a cold box (200) as a first output end of an air compression and purification unit (100); 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 (113), and the second input end of the fourth cooler (115) are connected in parallel as the second input end of the air compression and purification unit (100) and are connected to the first output end of the heat storage unit (700); the second output end of the first cooler (102), the second output end of the second cooler (104), the second output end of the third cooler (106), and the second output end of the fourth cooler (108) are connected in parallel as the second output end of the air compression and purification unit (100) and are connected to the first input end of the heat storage unit (700); a second three-way valve (116), wherein a first port of the second three-way valve (116) is connected to a second input end of the water cooling tower (108), and a third port of the second three-way valve (116) is connected to a fourth output end of the cold box (200) as a fourth input end of the air compression purification unit (100); A desorption tower (117), wherein the input end of the desorption tower (117) is connected to the second port of the second three-way valve (116), and the output end of the desorption tower (117) is discharged to the air.

4. The liquid air energy storage nitrogen and electricity combined supply system according to claim 3, characterized in that: The cold box (200) comprises: An air cooler (201), wherein a first input end of the air cooler (201) is connected to a first output end of the air compression purification unit (100) as a first input end of the cold box (200), a second input end of the air cooler (201) is connected to a first output end of the cold storage unit (500) as a second input end of the cold box (200), a third input end of the air cooler (201) is connected to a first output end of the nitrogen production unit (400) as a third input end of the cold box (200), and a fourth input end of the air cooler (201) is connected to a first output end of the nitrogen production unit (400) as a fourth input end of the cold box The fourth input end of (200) is connected to the second output end of the nitrogen production unit (400), the second output end of the air cooler (201) is connected to the first input end of the cold storage unit (500) as the second output end of the cold box (200), the third output end of the air cooler (201) is connected to the third input end of the air compression and purification unit (100) as the third output end of the cold box (200), and the fourth output end of the air cooler (201) is connected to the fourth input end of the air compression and purification unit (100) as the fourth output end of the cold box (200); A refrigeration expander (202), wherein the input end of the refrigeration expander (202) is connected to the fifth output end of the air cooler (201), and the output end of the refrigeration expander (202) is connected to the second input end of the nitrogen production unit (400) as the fifth output end of the cold box (200); A first throttle valve (203), wherein the input end of the first throttle valve (203) is connected to the first output end of the air cooler (201), and the output end of the first throttle valve (203) is connected to the input end of the gas-liquid separator (300) as the first output end of the cold box (200).

5. The liquid air energy storage nitrogen and electricity combined supply system according to claim 4, characterized in that: The nitrogen production unit (400) comprises: A third three-way valve (401), wherein a first port of the third three-way valve (401) is supplied to a user, and a third port of the third three-way valve (401) is connected to a second output end of the distillation column (403); A condenser evaporator (402), wherein a first input end of the condenser evaporator (402) is connected to an output end of the second throttle valve (404), a second input end of the condenser evaporator (402) is connected to a second port of the third three-way valve (401), and a second output end of the condenser evaporator (402) is connected to a fourth input end of the cold box (200) as a second output end of the nitrogen production unit (400); A distillation tower (403), wherein a first input end of the distillation tower (403) is connected to an output end of a second switch valve (407), a second input end of the distillation tower (403) is connected to an output end of a first switch valve (405), a third input end of the distillation tower (403) is connected to a first port of a sixth three-way valve (411), and a fourth input end of the distillation tower (403) is connected to a first output end of a condenser evaporator (402); a second throttle valve (404), wherein an input end of the second throttle valve (404) is connected to a first output end of the distillation column (403); a first switch valve (405), wherein an input end of the first switch valve (405) is connected to a first port of the seventh three-way valve (412); a liquid air pump (406), wherein the input end of the liquid air pump (406) is connected to the first output end of the air expansion power generation unit (600) as the third input end of the nitrogen production unit (400), and the output end of the liquid air pump (406) is connected to the second port of the seventh three-way valve (412); a second switch valve (407), wherein an input end of the second switch valve (407) is connected to a second port of the fifth three-way valve (410); a third switch valve (408), wherein an input end of the third switch valve (408) is connected to a third port of the fifth three-way valve (410); a fourth three-way valve (409), wherein the first port of the fourth three-way valve (409) is connected to the fifth output end of the cold box (200) as the second input end of the nitrogen production unit (400), and the second port of the fourth three-way valve (409) is connected to the third input end of the cold box (200) as the first output end of the nitrogen production unit (400); and the third port of the fourth three-way valve (409) is connected to the output end of the third switch valve (408); a fifth three-way valve (410), wherein a first port of the fifth three-way valve (410) serves as a first input end of the nitrogen production unit (400) and is connected to a second output end of the gas-liquid separator (300); a sixth three-way valve (411), wherein the second port of the sixth three-way valve (411) is connected to the second output port of the air expansion power generation unit (600) as the fourth input port of the nitrogen production unit (400), and the third port of the sixth three-way valve (411) is connected to the third output port of the air expansion power generation unit (600) as the fifth input port of the nitrogen production unit (400); A seventh three-way valve (412), wherein the third port of the seventh three-way valve (412) serves as the third output end of the nitrogen production unit (400) and is connected to the second input end of the air expansion power generation unit (600).

6. The liquid air energy storage nitrogen and electricity combined supply system according to claim 5, characterized in that: The cold storage unit (500) comprises: A cold storage packed bed (501) having a left port and a right port; a first circulation fan (502), wherein an input end of the first circulation fan (502) is connected to the second output end of the cold box (200) as a first input end of the cold storage unit (500), and an output end of the first circulation fan (502) is connected to a left port of the cold storage packed bed (501); a second circulation fan (503), wherein the input end of the second circulation fan (503) is connected to the left port of the cold storage packed bed (501), and the output end of the second circulation fan (503) is connected to the third input end of the air expansion power generation unit (600) as the second output end of the cold storage unit (500); A fourth switch valve (504), wherein the input end of the fourth switch valve (504) is connected to the output end of the second circulation fan (503).

7. The liquid air energy storage nitrogen and electricity combined supply system according to claim 6, characterized in that: The air expansion power generation unit (600) comprises: A liquid air storage tank (601), wherein an input end of the liquid air storage tank (601) is connected to a first output end of the gas-liquid separator (300) as a first input end of the air expansion power generation unit (600), and a second output end of the liquid air storage tank (601) is connected to a third input end of the nitrogen production unit (400) as a first output end of the air expansion power generation unit (600); A cryogenic liquid pump (602), wherein the input end of the cryogenic liquid pump (602) is connected to the first output end of the liquid air storage tank (601) An evaporator (603), wherein a first input end of the evaporator (603) is connected to an output end of a cryogenic liquid pump (602), a second input end of the evaporator (603) is connected to a second output end of a cold storage unit (500) as a third input end of an air expansion power generation unit (600), a third input end of the evaporator (603) is connected to a third port of an eighth three-way valve (612), a fourth input end of the evaporator (603) is connected to an output end of a sixth switch valve (614), a second output end of the evaporator (603) is connected to a second input end of a cold storage unit (500) as a fourth output end of the air expansion power generation unit (600), and a third output end of the evaporator (603) is connected to a fourth input end of a nitrogen production unit (400) as a second output end of the air expansion power generation unit (600); a first heater (604), wherein a first input end of the first heater (604) is connected to a first output end of the evaporator (603); a first expansion generator (605), wherein an input end of the first expansion generator (605) is connected to a first output end of the first heater (604); A second heater (606), wherein a first input end of the second heater (606) is connected to an output end of the first expansion generator (605) a second expansion generator (607), wherein an input end of the second expansion generator (607) is connected to a first output end of the second heater (606); a third heater (608), wherein a first input end of the third heater (608) is connected to an output end of the second expansion generator (607); a third expansion generator (609), wherein an input end of the third expansion generator (609) is connected to a first output end of the third heater (608); a fourth heater (610), wherein a first input end of the fourth heater (610) is connected to an output end of the third expansion generator (609); a fourth expansion generator (611), wherein an input end of the fourth expansion generator (611) is connected to a first port of an eighth three-way valve (612); The second input end of the first heater (604), the second input end of the second heater (606), the second input end of the third heater (608), and the second input end of the fourth heater (610) are connected in parallel as the fourth input end of the air expansion power generation unit (600) and are connected to the second output end of the heat storage unit (700); the second output end of the first heater (604), the second output end of the second heater (606), the second output end of the third heater (608), and the second output end of the fourth heater (610) are connected in parallel as the fifth output end of the air expansion power generation unit (600) and are connected to the second input end of the heat storage unit (700); an eighth three-way valve (612), wherein a second port of the eighth three-way valve (612) is connected to a first output end of the fourth heater (610); a fifth switch valve (613), wherein the input end of the fifth switch valve (613) is connected to the fourth output end of the evaporator (603), and the output end of the fifth switch valve (613) is connected to the fifth input end of the nitrogen production unit (400) as the third output end of the air expansion power generation unit (600); A sixth switch valve (614), wherein the input end of the sixth switch valve (614) serves as the second input end of the air expansion power generation unit (600) and is connected to the third output end of the nitrogen production unit (400).

8. The liquid air energy storage nitrogen and electricity combined supply system according to claim 7, characterized in that: The heat storage unit (700) comprises: A heat storage tank (701), wherein an input end of the heat storage tank (701) serves as a first input end of the heat storage unit (700) and is connected to a second output end of the air compression purification unit (100); a first circulating water pump (702), wherein an input end of the first circulating water pump (702) is connected to an output end of the normal temperature storage tank (704), and an output end of the first circulating water pump (702) serves as a first output end of the heat storage unit (700) and is connected to a second input end of the air compression purification unit (100); a second circulating water pump (703), wherein the input end of the second circulating water pump (703) is connected to the output end of the heat storage tank (701), and the input and output ends of the second circulating water pump (703) serve as the second output end of the heat storage unit (700) and are connected to the fourth input end of the air expansion power generation unit (600); A normal temperature storage tank (704), wherein the input end of the normal temperature storage tank (704) serves as the second input end of the heat storage unit (700) and is connected to the fifth output end of the air expansion power generation unit (600).

9. A method for combining liquid air energy storage with nitrogen and electric energy supply, characterized in that: This is achieved by using a liquid air energy storage nitrogen and electricity combined supply system as described in claim 8. During the off-peak period of the power grid, the air liquefaction circulation loop and the nitrogen production circulation loop are operated in conjunction, and the air is purified and compressed to obtain high-pressure air, which is then cooled, pressurized, and separated to obtain liquid air and gaseous air. The liquid air is stored in the liquid air storage tank (601) of the air expansion power generation unit (600); the gaseous air is passed through the nitrogen production unit (400) to obtain nitrogen and liquid nitrogen; During peak hours of the power grid, the air power generation cycle and the nitrogen production cycle operate in conjunction, and the liquid air output from the liquid air storage tank (601) is divided into two streams. One stream of liquid air undergoes pressurization and liquid-gas phase change to recover evaporative cooling energy, and the other stream of liquid air passes through the nitrogen production unit (400) to obtain nitrogen and liquid nitrogen. During periods of grid flatness, the nitrogen production cycle operates to produce nitrogen gas and liquid nitrogen.

10. The method for combined supply of nitrogen and electric energy using liquid air energy storage according to claim 9, characterized in that: The air liquefaction circulation loop is as follows: The first input end of the air compression and purification unit (100) is used to input ambient air, the first output end of the air compression and purification unit (100) is connected to the first input end of the cold box (200), the second output end of the air compression and purification unit (100) is connected to the first input end of the heat storage unit (700), the second input end of the air compression and purification unit (100) is connected to the first output end of the heat storage unit (700), the third input end of the air compression and purification unit (100) is connected to the third output end of the cold box (200), and the fourth input end of the air compression and purification unit (100) is connected to the fourth output end of the cold box (200); The first output end of the cold box (200) is connected to the input end of the gas-liquid separator (300), the second output end of the cold box (200) is connected to the first input end of the cold storage unit (500), and the second input end of the cold box (200) is connected to the first output end of the cold storage unit (500); The nitrogen production cycle is as follows: The first input end of the nitrogen production unit (400) is connected to the second output end of the gas-liquid separator (300), the second input end of the nitrogen production unit (400) is connected to the fifth output end of the cold box (200), the third input end of the nitrogen production unit (400) is connected to the first output end of the air expansion power generation unit (600), the fourth input end of the nitrogen production unit (400) is connected to the second output end of the air expansion power generation unit (600), the fifth input end of the nitrogen production unit (400) is connected to the third output end of the air expansion power generation unit (600), the first output end of the nitrogen production unit (400) is connected to the third input end of the cold box (200), the second output end of the nitrogen production unit (400) is connected to the fourth input end of the cold box (200), and the third output end of the nitrogen production unit (400) is connected to the second input end of the air expansion power generation unit (600); The air power generation cycle is as follows: The first input end of the air expansion power generation unit (600) is connected to the first output end of the gas-liquid separator (300), the third input end of the air expansion power generation unit (600) is connected to the second output end of the cold storage unit (500), the fourth input end of the air expansion power generation unit (600) is connected to the second output end of the heat storage unit (700), the fourth output end of the air expansion power generation unit (600) is connected to the second input end of the cold storage unit (500), and the fifth output end of the air expansion power generation unit (600) is connected to the second input end of the heat storage unit (700); During the off-peak period of the power grid, the air liquefaction cycle and the nitrogen production cycle are operated in conjunction: after the ambient air is compressed in two stages and cooled between stages, it enters the air cooling tower (105) to cool down, and then enters the adsorption tower (110) to remove water, carbon dioxide or alkanes in the air, and then is further compressed to high pressure by the third compressor (112) and the fourth compressor (114). At the same time, the compression heat generated by the air compression process is recovered by the heat exchange fluid and stored in the heat storage unit (700); the high-pressure air output by the air compression and purification unit (100) enters the air cooler (201), a part of the pre-cooled air passes through the refrigeration expander (202), and the other part continues to cool down and throttle and reduce the pressure, and then enters the gas-liquid separator (300) to separate the liquid air and gaseous air, wherein the liquid air is stored in the liquid air storage tank (601) and the gaseous air is divided into two parts. The air entering the distillation tower (403) is separated, one part is combined with the cold air coming out of the refrigeration expander (202) and then flows back to the air cooler (201) to release the cold energy, and then enters the first three-way valve (111), and the other part directly enters the distillation tower (403); the air entering the distillation tower (403) is separated, and oxygen-rich liquid air is obtained at the bottom of the distillation tower (403), and nitrogen is obtained at the top of the distillation tower (403); the oxygen-rich liquid air extracted from the bottom of the distillation tower (403) undergoes liquid-gas phase change through the condenser evaporator (402), and then enters the air cooler (201) for reheating, and then is divided into two parts, one part is used as regeneration gas for the desorption tower (117), and the other part is supplied to the water cooling tower (108); the nitrogen at the top of the distillation tower (403) is divided into two streams, one is directly supplied to the user, and the other is cooled by the condenser evaporator (402) to become liquid nitrogen and flows back to the distillation tower (403); During the peak period of the power grid, the air power generation cycle and the nitrogen production cycle are operated in conjunction: the liquid air output from the liquid air storage tank (601) is divided into two streams, one of which is pressurized to high pressure by the cryogenic liquid pump (602), and then enters the evaporator (603) to undergo a liquid-gas phase change process, and the evaporation cold energy is recovered and stored in the cold storage packed bed (501) through the heat exchange fluid. The high-pressure air at the outlet of the evaporator (603) is divided into two parts after three-stage expansion and inter-stage heating. One part flows back to the evaporator (603) and enters the distillation tower (403), and the other part continues to expand to generate power; the other part passes through the liquid air pump (406) and then directly enter the distillation tower (403); the air entering the distillation tower (403) 403 is separated, and oxygen-rich liquid air is obtained at the bottom of the distillation tower (403), and nitrogen is obtained at the top of the distillation tower (403); the oxygen-rich liquid air extracted from the bottom of the distillation tower (403) undergoes liquid-gas phase change through the condenser evaporator (402), and then enters the air cooler (201) to be reheated to room temperature, and then discharged to the external environment; the nitrogen at the top of the distillation tower (403) is divided into two streams, one of which is directly supplied to the user, and the other is cooled by the condenser evaporator (102) to become liquid nitrogen and reflux to the distillation tower (403); During the grid flat period, the nitrogen production cycle is operated: the liquid air output from the liquid air storage tank (601) is divided into two parts after passing through the liquid air pump (602), one part directly enters the distillation tower (403), and the other part undergoes liquid-gas phase change through the evaporator (603) to become low-temperature gaseous air, and then enters the distillation tower (403). The air entering the distillation tower (403) is separated, and oxygen-rich liquid air is obtained at the bottom of the distillation tower (403), and nitrogen is obtained at the top of the distillation tower (403); the oxygen-rich liquid air extracted from the bottom of the distillation tower (403) undergoes liquid-gas phase change through the condenser evaporator (402), and then enters the air cooler (201) to be reheated to room temperature, and then discharged to the external environment. The nitrogen at the top of the distillation tower (403) is divided into two streams, one of which is directly supplied to users, and the other is cooled by the condenser evaporator (402) to become liquid nitrogen and reflux to the distillation tower (403).

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