Liquid air energy storage device and method based on backflow cold storage circulation

Abstract

The invention relates to the technical field of liquid air energy storage, in particular to a liquid air energy storage device and method based on backflow cold storage circulation. The air liquefaction circulation loop comprises an air compressor unit, an air purification unit, a cold box, a liquid air storage tank, a cold storage unit and a heat storage unit. In the electricity utilization trough period, after being purified, compressed and cooled, ambient air is expanded and depressurized to obtain liquid air, meanwhile, air compression heat energy is recycled and stored, and cold energy of the cold storage unit is reused through circulation air flowing out of the air purification unit to strengthen the liquefaction performance; in the peak period of power utilization, liquid air enters the power generation expansion unit for power generation after being pressurized, evaporated and heated, and evaporation cold energy is recycled and stored through outlet gas of the power generation expansion unit. The cold energy recovery and storage efficiency of the solid cold storage packed bed is improved through the structural form of backflow cold storage circulation, and air compression heat energy is effectively distributed and utilized.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid air energy storage, and in particular to a liquid air energy storage device and method based on a reflux cold storage cycle. Background Art

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

[0003] In the liquid air energy storage system, the recovery and utilization of low-temperature cold energy during the liquid air vaporization process is the key to improving the system's cycle power generation efficiency. The solid cold storage packed bed is the most recognized cold storage structure in the industry. The pipeline connects the cold box and the evaporator, usually including a closed-loop cold charging process and a cold releasing process. However, in a closed-loop cycle, it is difficult to completely remove the cold energy in the bed, and the flow of the heat transfer fluid also requires the fan to provide positive pressure to overcome the transmission resistance, thereby consuming a lot of electricity. Summary of the invention

[0004] The purpose of the present invention is to solve the shortcomings of the prior art and propose a liquid air energy storage device and method based on a reflux cold storage cycle, which cancels the setting of the closed-loop system of the cold storage unit and uses the exhaust gas of the air power generation process and the reflux gas of the air liquefaction process as the heat transfer fluid for the cold storage unit charging and releasing cold processes. The invention simplifies the system structure, avoids the problem of air replenishment during closed cycle pressure fluctuations, improves the energy utilization rate of the cold storage unit, and ultimately improves the system cycle power generation efficiency.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions: A liquid air energy storage device based on a reflux cold storage cycle, comprising an air liquefaction cycle loop and an air power generation cycle loop; The air liquefaction circulation loop includes an air compressor unit, an air purification unit, a cold box, a liquid air storage tank, a cold storage unit and a heat storage unit; The first input end of the air compressor group is used to input ambient air, the first output end of the air compressor group is connected to the first input end of the cold box, the second output end of the air compressor group is connected to the first input end of the air purification unit, the third output end of the air compressor group is connected to the first input end of the heat storage unit, the second input end of the air compressor group is connected to the first output end of the heat storage unit, and the third input end of the air compressor group is connected to the first output end of the air purification unit; the fourth input end of the air compressor group is connected to the first output end of the cold box; The second output end of the air purification unit is connected to the first input end of the cold storage unit; The second input end of the cold box is connected to the first output end of the cold storage unit, and the second output end of the cold box is connected to the first input end of the liquid air storage tank; The air power generation cycle loop includes a cold storage unit, a heat storage unit, a liquid air storage tank, a cryogenic liquid pump, an evaporator and a power generation expansion unit; The input end of the cryogenic liquid pump is connected to the output end of the liquid air storage tank, and the output end of the cryogenic liquid pump is connected to the first input end of the evaporator; The first output end of the evaporator is connected to the first input end of the power generation expansion unit, the second output end of the evaporator is connected to the second input end of the cold storage unit, and the second input end of the evaporator is connected to the second output end of the cold storage unit; The first output end of the power generation expansion machine group is connected to the third input end of the cold storage unit, the second input end of the power generation expansion machine group is connected to the second output end of the heat storage unit, and the second output end of the power generation expansion machine group is connected to the second input end of the heat storage unit; The air liquefaction circulation loop is used to purify, compress and cool ambient air, expand and reduce the pressure to obtain liquid air, and the liquid air is transmitted to the air power generation circulation loop, and the air compression heat generated during the compression process is stored in the heat storage unit; The air power generation cycle loop pressurizes, evaporates and further heats the received liquid air to expand and generate electricity, and the cold energy generated in the liquid air vaporization process is stored in the cold storage unit.

[0006] Preferably, the air compressor unit comprises: a first compressor, wherein an input end of the first compressor serves as a first input end of an air compressor unit; a first cooler, wherein a first input end of the first cooler is connected to an output end of the first compressor; a second compressor, wherein an input end of the second compressor is connected to a first output end of the first cooler; A second cooler, wherein a first input end of the second cooler is connected to an output end of the second compressor, and a first output end of the second cooler is connected to a first input end of the air purification unit as a second output end of the air compressor unit; a first circulating gas three-way valve, wherein a first port of the first circulating gas three-way valve is connected to a first output end of the air purification unit as a third input end of the air compressor group, and a second port of the first circulating gas three-way valve is connected to a first output end of the cold box as a fourth input end of the air compressor group; a third compressor, wherein an input end of the third compressor is connected to a third port of the first circulating gas three-way valve; a third cooler, wherein a first input end of the third cooler is connected to an output end of the third compressor; a fourth compressor, wherein an input end of the fourth compressor is connected to a first output end of the third cooler; 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 is connected to a first input end of the cold box as a first output end of an air compressor unit; 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 compressor group and 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 third output end of the air compressor group and connected to the first input end of the heat storage unit.

[0007] Preferably, the air purification unit comprises: a first adsorption tower having an upper port and a lower port; a second adsorption tower having an upper port and a lower port; a first air three-way valve, wherein a first port of the first air three-way valve is connected to an upper port of the first adsorption tower, and a second port of the first air three-way valve is connected to an upper port of the second adsorption tower; a second air three-way valve, wherein a first port of the second air three-way valve is connected to a lower port of the first adsorption tower, and a second port of the second air three-way valve is connected to a lower port of the second adsorption tower; a third air three-way valve, wherein the first port of the third air three-way valve is connected to the third input end of the air compressor unit as the first output end of the air purification unit, the second port of the third air three-way valve is connected to the first input end of the cold storage unit as the second output end of the air purification unit, and the third port of the third air three-way valve is connected to the third port of the first air three-way valve; A precooler, wherein the precooler input end serves as the first input end of the air purification unit, and the precooler output end is connected to the third port of the second air three-way valve.

[0008] Preferably, the cold box comprises: An air cooler, wherein a first input end of the air cooler is connected to a first output end of the air compressor unit as a first input end of a cold box, and a second input end of the air cooler is connected to a first output end of the cold storage unit as a second input end of the cold box; a gas cryogenic expander, wherein an input end of the gas cryogenic expander is connected to a first output end of the air cooler, and an output end of the gas cryogenic expander is connected to a third input end of the air cooler; a liquid cryogenic expander, wherein an input end of the liquid cryogenic expander is connected to a second output end of the air cooler; A cryogenic throttle valve, the input end of which is connected to the output end of the liquid cryogenic expander; A gas-liquid separator, wherein the input end of the gas-liquid separator is connected to the output end of the low-temperature throttle valve, the first output end of the gas-liquid separator is connected to the third input end of the air cooler, and the second output end of the gas-liquid separator is connected to the first input end of the liquid air storage tank as the second output end of the cold box; a second circulating gas three-way valve, wherein a first input end of the second circulating gas three-way valve is connected to a third output end of the air cooler, and a second input end of the second circulating gas three-way valve is connected to a fourth output end of the air cooler; The first circulation fan, the input end of the first circulation fan is connected to the output end of the second circulation gas three-way valve, and the output end of the first circulation fan is connected to the fourth input end of the air compressor group as the first output end of the cold box.

[0009] Preferably, the power generation expansion unit comprises: a first heater, wherein a first input end of the first heater is connected to a first output end of the evaporator as a first input end of a power generation expansion unit; a first power-generating expander, wherein an input end of the first power-generating expander is connected to a first output end of the first heater; a second heater, a first input end of the second heater being connected to an output end of the first power-generating expander; a second power-generating expander, wherein an input end of the second power-generating expander is connected to a first output end of the second heater; a third heater, a first input end of the third heater being connected to an output end of the second power-generating expander; a third power-generating expander, wherein an input end of the third power-generating expander is connected to a first output end of the third heater; a fourth heater, wherein a first input end of the fourth heater is connected to an output end of the third power-generating expander; a fourth power-generating expander, wherein the input end of the fourth power-generating expander is connected to the first output end of the fourth heater, and the output end of the fourth power-generating expander is connected to the third input end of the cold storage unit as the first output end of the power-generating expander group; 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 second input end of the power generation expansion unit and are 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 second output end of the power generation expansion unit and are connected to the second input end of the heat storage unit.

[0010] Preferably, the cold storage unit comprises: a solid cold storage packed bed having an upper port and a lower port; a first cold fluid three-way valve, wherein a first port of the first cold fluid three-way valve is connected to an upper port of the solid cold storage packed bed, and a second port of the first cold fluid three-way valve is connected as a first input end of a cold storage unit; a second cold fluid three-way valve, wherein a first port of the second cold fluid three-way valve is connected to a lower port of the solid cold storage packed bed, and a second port of the second cold fluid three-way valve is connected to a second output end of the evaporator; A filter, wherein the filter input end is connected to the third port of the second cold fluid three-way valve, and the filter output end is connected to the second input end of the cold box as the first output end of the cold storage unit; a third cold fluid three-way valve, wherein a first port of the third cold fluid three-way valve is connected to a third port of the first cold fluid three-way valve, and a second port of the third cold fluid three-way valve is connected to an external environment; a second circulation fan, wherein an input end of the second circulation fan is connected to a third port of the third cold fluid three-way valve; A fourth cold fluid three-way valve, wherein the first port of the fourth cold fluid three-way valve is connected to the output end of the second circulation fan, the second port of the fourth cold fluid three-way valve is connected to the first output end of the power generation expansion unit as the third input end of the cold storage unit, and the third port of the fourth cold fluid three-way valve is connected to the second input end of the evaporator as the second output end of the cold storage unit.

[0011] Preferably, the heat storage unit comprises: A normal temperature water tank having an upper port and a lower port, wherein the lower port is connected to the second output end of the power generation expansion unit as a second input end of the heat storage unit; a first circulating water pump, wherein an input end of the first circulating water pump is connected to an upper port of the normal temperature water tank, and an output end of the first circulating water pump is connected to a second input end of the air compressor unit as a first output end of the heat storage unit; a hot water tank having an upper port and a lower port, wherein the upper port is connected to the third output end of the air compressor unit as a first input end of the heat storage unit; A second circulating water pump, wherein the input end of the second circulating water pump is connected to the lower port of the hot water tank, and the output end of the second circulating water pump is connected to the second input end of the power generation expander as the second output end of the heat storage unit.

[0012] The present invention also provides a liquid air energy storage method based on a reflux cold storage cycle, which is implemented by using the liquid air energy storage device based on a reflux cold storage cycle as described above, and comprises: Air liquefaction cycle process: After being initially compressed by the first compressor and the second compressor and cooled by the first cooler and the second cooler, the ambient air enters the air purification unit 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 using a heat exchange fluid (such as pressurized water) and stored in the heat storage unit; the high-pressure air output by the air compressor unit enters the cold box and is cooled to liquid and stored in the liquid air storage tank, and the air liquefaction rate is increased by carrying the cold energy in the solid cold storage packed bed through a circulating gas from the air purification unit; Air power generation cycle process: the liquid air output from the liquid air storage tank is pressurized to high pressure by a low-temperature liquid pump, and then enters the evaporator to undergo a liquid-gas phase change process. The phase change cold energy is recovered and stored in the cold storage unit through the outlet gas of the power generation expander; the vaporized high-pressure air enters the power generation expander, is heated to high temperature by a part of the compression heat stored in the heat storage unit, and then expands to generate electricity.

[0013] Among them, the refrigerator cooling step and the heat regeneration step required in the adsorption and desorption process of the first adsorption tower and the second adsorption tower in the air purification unit can be driven and completed by utilizing the residual compression heat.

[0014] By adopting the above technical solution: during the period of low electricity consumption, the ambient air is purified, compressed and cooled, and then expanded and reduced in pressure to obtain liquid air. At the same time, the air compression heat energy is recovered and stored, and the cold energy of the cold storage unit is reused through a circulating gas out of the air purification unit to enhance the liquefaction performance; during the period of peak electricity consumption, the liquid air is pressurized, evaporated, vaporized and heated, and then enters the power generation expansion unit to generate electricity. At the same time, the outlet gas of the power generation expander is used to recover and store the evaporation and vaporization cold energy.

[0015] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention adopts a reflux cold storage cycle structure, which effectively simplifies system control and makes the operation strategy simpler.

[0016] 2. The present invention can reduce the energy consumption of the circulating fan in the charging and cooling process and improve the power generation efficiency of the liquid air energy storage system.

[0017] 3. The present invention can effectively improve the exergy efficiency of the cold storage unit, thereby improving the power generation efficiency of the liquid air energy storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0018] Figure 1 It is a structural schematic diagram of the present invention; Figure 2 It is a structural schematic diagram of the air purification unit in the present invention; Figure 3 It is a structural schematic diagram of the cold box in the present invention; Figure 4 It is a structural schematic diagram of the cold storage unit in the present invention.

[0019] In the figure: 100 air compressor unit, 101 first compressor, 102 first cooler, 103 second compressor, 104 second cooler, 105 third compressor, 106 third cooler, 107 fourth compressor, 108 fourth cooler, 109 first circulating gas three-way valve, 200 air purification unit, 201 first adsorption tower, 202 second adsorption tower, 203 first air three-way valve, 204 second air three-way valve, 205 third air three-way valve, 206 precooler, 300 cold box, 301 air cooler, 302 gas cryogenic expander, 303 liquid cryogenic expander, 304 cryogenic throttle valve, 305 gas-liquid separator, 306 second circulating gas three-way valve, 307 first circulating fan, 400 liquid air storage tank, 500 cryogenic liquid pump, 600 evaporator, 700 cold storage unit, 701 solid cold storage packed bed, 702 first cold fluid three-way valve, 703 second cold fluid three-way valve, 704 filter, 705 third cold fluid three-way valve, 706 second circulating fan, 707 fourth cold fluid three-way valve, 800 power generation expansion unit, 801 first heater, 802 first power generation expansion machine, 803 second heater, 804 second power generation expansion machine, 805 third heater, 806 third power generation expansion machine, 807 fourth heater, 808 fourth power generation expansion machine, 900 heat storage unit, 901 normal temperature water tank, 902 first circulating water pump, 903 hot water tank, 904 second circulating water pump. DETAILED DESCRIPTION

[0020] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings, so that those skilled in the art can better understand the advantages and features of the present invention, thereby making a clearer definition of the protection scope of the present invention. The embodiments described in the present invention are only a part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments in the present invention, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present invention.

[0021] A liquid air energy storage device based on a reflux cold storage cycle, comprising an air liquefaction cycle loop and an air power generation cycle loop; The air liquefaction circulation loop includes an air compressor unit 100, an air purification unit 200, a cold box 300, a liquid air storage tank 400, a cold storage unit 700 and a heat storage unit 900; The first input end of the air compressor group 100 is used to input ambient air, the first output end of the air compressor group 100 is connected to the first input end of the cold box 300, the second output end of the air compressor group 100 is connected to the first input end of the air purification unit 200, the third output end of the air compressor group 100 is connected to the first input end of the heat storage unit 900, the second input end of the air compressor group 100 is connected to the first output end of the heat storage unit 900, and the third input end of the air compressor group 100 is connected to the first output end of the air purification unit 200; the fourth input end of the air compressor group 100 is connected to the first output end of the cold box 300; The second output end of the air purification unit 200 is connected to the first input end of the cold storage unit 700; The second input end of the cold box 300 is connected to the first output end of the cold storage unit 700, and the second output end of the cold box 300 is connected to the first input end of the liquid air storage tank 400; The air power generation cycle loop includes a cold storage unit 700, a heat storage unit 900, a liquid air storage tank 400, a cryogenic liquid pump 500, an evaporator 600 and a power generation expansion unit 800; The input end of the cryogenic liquid pump 500 is connected to the output end of the liquid air storage tank 400, and the output end of the cryogenic liquid pump 500 is connected to the first input end of the evaporator 600; The first output end of the evaporator 600 is connected to the first input end of the power generation expansion unit 800, the second output end of the evaporator 600 is connected to the second input end of the cold storage unit 700, and the second input end of the evaporator 600 is connected to the second output end of the cold storage unit 700; The first output end of the power generation expansion unit 800 is connected to the third input end of the cold storage unit 700, the second input end of the power generation expansion unit 800 is connected to the second output end of the heat storage unit 900, and the second output end of the power generation expansion unit 800 is connected to the second input end of the heat storage unit 900; The air liquefaction circulation loop is used to purify, compress and cool the ambient air, expand and reduce the pressure to obtain liquid air, and the liquid air is transmitted to the air power generation circulation loop, and the air compression heat generated during the compression process is stored in the heat storage unit 900; The air power generation cycle pressurizes, evaporates and further heats the received liquid air to expand and generate electricity, and the cold energy generated by the liquid air vaporization process is stored in the cold storage unit 700.

[0022] Specifically, the air compressor unit 100 includes: A first compressor 101, wherein an input end of the first compressor 101 serves as a first input end of the air compressor 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, and a first output end of the second cooler 104 is connected to a first input end of the air purification unit 200 as a second output end of the air compressor unit 100; A first circulating gas three-way valve 109, wherein a first port of the first circulating gas three-way valve 109 is connected to a first output end of the air purification unit 200 as a third input end of the air compressor unit 100, and a second port of the first circulating gas three-way valve 109 is connected to a first output end of the cold box 300 as a fourth input end of the air compressor unit 100; A third compressor 105, wherein an input end of the third compressor 105 is connected to a third port of the first circulating gas three-way valve 109; A third cooler 106, wherein a first input end of the third cooler 106 is connected to an output end of the third compressor 105; a fourth compressor 107, wherein an input end of the fourth compressor 107 is connected to a first output end of the third cooler 106; A fourth cooler 108, wherein a first input end of the fourth cooler 108 is connected to an output end of the fourth compressor 107; a first output end of the fourth cooler 108 is connected to a first input end of the cold box 300 as a first output end of the air compressor 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 106 and the second input end of the fourth cooler 108 are connected in parallel as the second input end of the air compressor group 100 and connected to the first output end of the heat storage unit 900; 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 third output end of the air compressor group 100 and connected to the first input end of the heat storage unit 900.

[0023] Specifically, the air purification unit 200 includes: A first adsorption tower 201 having an upper port and a lower port; A second adsorption tower 202 having an upper port and a lower port; a first air three-way valve 203, wherein a first port of the first air three-way valve 203 is connected to an upper port of the first adsorption tower 201, and a second port of the first air three-way valve 203 is connected to an upper port of the second adsorption tower 202; a second air three-way valve 204, wherein a first port of the second air three-way valve 204 is connected to a lower port of the first adsorption tower 201, and a second port of the second air three-way valve 204 is connected to a lower port of the second adsorption tower 202; A third air three-way valve 205, wherein a first port of the third air three-way valve 205 is connected to a third input end of the air compressor unit 100 as a first output end of the air purification unit 200, a second port of the third air three-way valve 205 is connected to a first input end of the cold storage unit 700 as a second output end of the air purification unit 200, and a third port of the third air three-way valve 205 is connected to a third port of the first air three-way valve 203; The precooler 206 has an input end serving as a first input end of the air purification unit, and an output end of the precooler 206 connected to a third port of the second air three-way valve 204 .

[0024] Specifically, the cold box 300 includes: An air cooler 301, wherein a first input end of the air cooler 301 is connected to a first output end of the air compressor unit 100 as a first input end of the cold box 300, and a second input end of the air cooler 301 is connected to a first output end of the cold storage unit 700 as a second input end of the cold box 300; A gas cryogenic expander 302, wherein the input end of the gas cryogenic expander 302 is connected to the first output end of the air cooler 301, and the output end of the gas cryogenic expander 302 is connected to the third input end of the air cooler 301; A liquid cryogenic expander 303, wherein the input end of the liquid cryogenic expander 303 is connected to the second output end of the air cooler 301; A low temperature throttle valve 304, wherein the input end of the low temperature throttle valve 304 is connected to the output end of the liquid low temperature expander 303; A gas-liquid separator 305, wherein the input end of the gas-liquid separator 305 is connected to the output end of the low-temperature throttle valve 304, the first output end of the gas-liquid separator 305 is connected to the third input end of the air cooler 301, and the second output end of the gas-liquid separator 305 is connected to the first input end of the liquid air storage tank 400 as the second output end of the cold box 300; a second circulating gas three-way valve 306, wherein a first input end of the second circulating gas three-way valve 306 is connected to a third output end of the air cooler 301, and a second input end of the second circulating gas three-way valve 306 is connected to a fourth output end of the air cooler 301; The first circulation fan 307, the input end of the first circulation fan 307 is connected to the output end of the second circulation gas three-way valve 306, and the output end of the first circulation fan 307 is connected to the fourth input end of the air compressor unit 100 as the first output end of the cold box.

[0025] Specifically, the power generation expansion unit 800 includes: A first heater 801, wherein a first input end of the first heater 801 is connected to a first output end of the evaporator 600 as a first input end of the power generation expansion unit 800; A first power-generating expander 802, wherein an input end of the first power-generating expander 802 is connected to a first output end of the first heater 801; A second heater 803, wherein a first input end of the second heater 803 is connected to an output end of the first power generation expander 802; a second power-generating expander 804, wherein an input end of the second power-generating expander 804 is connected to a first output end of the second heater 803; A third heater 805, wherein a first input end of the third heater 805 is connected to an output end of the second power generation expander 804; a third power-generating expander 806, wherein an input end of the third power-generating expander 806 is connected to a first output end of the third heater 805; a fourth heater 807, wherein a first input end of the fourth heater 807 is connected to an output end of the third power generation expander 806; A fourth power generation expander 808, wherein the input end of the fourth power generation expander 808 is connected to the first output end of the fourth heater 807, and the output end of the fourth power generation expander 808 is connected to the third input end of the cold storage unit 700 as the first output end of the power generation expander group 800; The second input end of the first heater 801, the second input end of the second heater 803, the second input end of the third heater 805 and the second input end of the fourth heater 807 are connected in parallel as the second input end of the power generation expansion unit 800 and are connected to the second output end of the heat storage unit 900; the second output end of the first heater 801, the second output end of the second heater 803, the second output end of the third heater 805 and the second output end of the fourth heater 807 are connected in parallel as the second output end of the power generation expansion unit 800 and are connected to the second input end of the heat storage unit 900.

[0026] Specifically, the cold storage unit 700 includes: Solid cold storage packed bed 701, which has an upper port and a lower port; A first cold fluid three-way valve 702, wherein a first port of the first cold fluid three-way valve 702 is connected to an upper port of the solid cold storage filled bed 701, and a second port of the first cold fluid three-way valve 702 is connected as a first input end of the cold storage unit 700; A second cold fluid three-way valve 703, wherein a first port of the second cold fluid three-way valve 703 is connected to a lower port of the solid cold storage filled bed 701, and a second port of the second cold fluid three-way valve 703 is connected to a second output end of the evaporator 600; A filter 704, wherein the input end of the filter 704 is connected to the third port of the second cold fluid three-way valve 703, and the output end of the filter 704 is connected to the second input end of the cold box 300 as the first output end of the cold storage unit 700; A third cold fluid three-way valve 705, wherein a first port of the third cold fluid three-way valve 705 is connected to a third port of the first cold fluid three-way valve 702, and a second port of the third cold fluid three-way valve 705 is connected to the external environment; A second circulation fan 706, wherein an input end of the second circulation fan 706 is connected to a third port of the third cold fluid three-way valve 705; A fourth cold fluid three-way valve 707, wherein the first port of the fourth cold fluid three-way valve 707 is connected to the output end of the second circulation fan 706, the second port of the fourth cold fluid three-way valve 707 is connected to the first output end of the power generation expansion unit 800 as the third input end of the cold storage unit 700, and the third port of the fourth cold fluid three-way valve 707 is connected to the second input end of the evaporator 600 as the second output end of the cold storage unit 700.

[0027] Specifically, the heat storage unit 900 includes: A normal temperature water tank 901, which has an upper port and a lower port, wherein the lower port is connected to the second output end of the power generation expansion unit 800 as the second input end of the heat storage unit 900; A first circulating water pump 902, wherein an input end of the first circulating water pump 902 is connected to an upper port of the normal temperature water tank 901, and an output end of the first circulating water pump 902 is connected to a second input end of the air compressor unit 100 as a first output end of the heat storage unit 900; A hot water tank 903, which has an upper port and a lower port, wherein the upper port is connected to the third output end of the air compressor unit 100 as the first input end of the heat storage unit 900; The second circulating water pump 904 has an input end connected to the lower port of the hot water tank 903 , and an output end of the second circulating water pump 904 is connected to the second input end of the power generation expansion unit 800 as the second output end of the heat storage unit 900 .

[0028] A liquid air energy storage method based on a reflux cold storage cycle, the method is implemented by using the liquid air energy storage device based on a reflux cold storage cycle as described above, comprising: Air liquefaction cycle process: After being preliminarily compressed by the first compressor 101 and the second compressor 103 and cooled by the first cooler 102 and the second cooler 104, the ambient air enters the air purification unit 200 to remove water, carbon dioxide, alkanes and other components in the air, and then is further compressed to high pressure by the third compressor 105 and the fourth compressor 107. At the same time, the compression heat generated by the air compression process is recovered by using a heat exchange fluid (such as pressurized water) and stored in the heat storage unit 900; the high-pressure air output by the air compressor unit 100 enters the cold box 300 to be cooled to liquid and stored in the liquid air storage tank 400, and the cold energy in the solid cold storage packed bed 701 is carried out by a circulating gas from the air purification unit 200 to improve the air liquefaction rate; Air power generation cycle process: the liquid air output from the liquid air storage tank 400 is pressurized to high pressure by the low-temperature liquid pump 500, and then enters the evaporator 600 to undergo a liquid-gas phase change process, and the phase change cold energy is recovered and stored in the cold storage unit 700 through the outflow gas of the power generation expansion unit 800; the vaporized high-pressure air enters the power generation expansion unit 800, is heated to high temperature by a part of the compression heat stored in the heat storage unit 900, and then expands to generate electricity.

[0029] The refrigeration machine cooling step and the heat regeneration step required in the adsorption and desorption process of the first adsorption tower 201 and the second adsorption tower 202 in the air purification unit 200 can be driven and completed by utilizing the residual compression heat.

[0030] In this embodiment, during the period of low electricity consumption, the ambient air is purified, compressed and cooled, and then expanded and reduced in pressure to obtain liquid air. At the same time, the air compression heat energy is recovered and stored, and the cold energy of the cold storage unit is reused through a circulating gas leaving the air purification unit to enhance the liquefaction performance. During the period of peak electricity consumption, the liquid air is pressurized, evaporated, vaporized and heated, and then enters the power generation expansion unit to generate electricity. At the same time, the outlet gas of the power generation expansion unit is used to recover and store the evaporated cold energy.

[0031] In order to further illustrate the embodiments of the present invention, Figure 1 The liquid air energy storage system based on the reflux cold storage cycle is simulated and calculated, in which the cold storage unit adopts the form of solid cold storage packed bed and the heat storage unit adopts the form of pressurized water tank. Table 1 shows the parameters of the key points of the system operation. Considering 95% cold storage exergy efficiency, the system liquefaction rate is 57%, and the system cycle power generation efficiency is 58.2%. In the liquid air energy storage system of the same 50MW level, the study compares the two cold storage structures of reflux and closed. Since the cold storage exergy efficiency of the reflux cold storage cycle structure is higher than that of the closed cold storage structure, the liquid air energy storage system based on the reflux cold storage cycle has a higher liquefaction rate, and the cycle power generation efficiency is about 15.57% higher than that of the liquid air energy storage system based on closed cold storage.

[0032]

[0033]

[0034]

[0035] In summary, the present invention improves the cold energy recovery and storage efficiency of the solid cold storage packed bed through the structural form of the reflux cold storage cycle, and effectively distributes and utilizes the air compression heat energy. It is an efficient and low-cost liquid air energy storage technology.

[0036] The description and practice disclosed in the present invention are easy to think and understand for ordinary technicians in the technical field, and several improvements and modifications can be made without departing from the principles of the present invention. Therefore, modifications or improvements made without departing from the spirit of the present invention should also be regarded as the protection scope of the present invention.

Claims

1. A liquid air energy storage device based on a reflux cold storage cycle, characterized in that: It includes an air liquefaction circulation loop and an air power generation circulation loop; The air liquefaction circulation loop comprises an air compressor unit (100), an air purification unit (200), a cold box (300), a liquid air storage tank (400), a cold storage unit (700) and a heat storage unit (900); The first input end of the air compressor unit (100) is used to input ambient air; the first output end of the air compressor unit (100) is connected to the first input end of the cold box (300); the second output end of the air compressor unit (100) is connected to the first input end of the air purification unit (200); the third output end of the air compressor unit (100) is connected to the first input end of the heat storage unit (900); the second input end of the air compressor unit (100) is connected to the first output end of the heat storage unit (900); the third input end of the air compressor unit (100) is connected to the first output end of the air purification unit (200); and the fourth input end of the air compressor unit (100) is connected to the first output end of the cold box (300); The second output end of the air purification unit (200) is connected to the first input end of the cold storage unit (700); The second input end of the cold box (300) is connected to the first output end of the cold storage unit (700), and the second output end of the cold box (300) is connected to the first input end of the liquid air storage tank (400); The air power generation circulation loop comprises a cold storage unit (700), a heat storage unit (900), a liquid air storage tank (400), a cryogenic liquid pump (500), an evaporator (600) and a power generation expansion unit (800); The input end of the cryogenic liquid pump (500) is connected to the output end of the liquid air storage tank (400), and the output end of the cryogenic liquid pump (500) is connected to the first input end of the evaporator (600); The first output end of the evaporator (600) is connected to the first input end of the power generation expansion unit (800), the second output end of the evaporator (600) is connected to the second input end of the cold storage unit (700), and the second input end of the evaporator (600) is connected to the second output end of the cold storage unit (700); The first output end of the power generation expansion unit (800) is connected to the third input end of the cold storage unit (700), the second input end of the power generation expansion unit (800) is connected to the second output end of the heat storage unit (900), and the second output end of the power generation expansion unit (800) is connected to the second input end of the heat storage unit (900); The air liquefaction circulation loop is used to purify, compress and cool ambient air, and then expand and reduce the pressure to obtain liquid air. The liquid air is transmitted to the air power generation circulation loop, and the air compression heat generated during the compression process is stored in the heat storage unit (900); The air power generation cycle pressurizes, evaporates and further heats the received liquid air to expand and generate electricity, and the cold energy generated in the liquid air vaporization process is stored in the cold storage unit (700).

2. A liquid air energy storage device based on a reflux cold storage cycle according to claim 1, characterized in that: The air compressor 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 compressor 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), and a first output end of the second cooler (104) is connected to a first input end of the air purification unit (200) as a second output end of the air compressor unit (100); a first circulating gas three-way valve (109), wherein a first port of the first circulating gas three-way valve (109) is connected to a first output end of the air purification unit (200) as a third input end of the air compressor unit (100), and a second port of the first circulating gas three-way valve (109) is connected to a first output end of the cold box (300) as a fourth input end of the air compressor unit (100); a third compressor (105), wherein an input end of the third compressor (105) is connected to a third port of the first circulating gas three-way valve (109); a third cooler (106), wherein a first input end of the third cooler (106) is connected to an output end of the third compressor (105); a fourth compressor (107), wherein an input end of the fourth compressor (107) is connected to a first output end of the third cooler (106); a fourth cooler (108), wherein a first input end of the fourth cooler (108) is connected to an output end of the fourth compressor (107); and a first output end of the fourth cooler (108) is connected to a first input end of the cold box (300) as a first output end of the air compressor 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 (106), and the second input end of the fourth cooler (108) are connected in parallel as the second input end of the air compressor group (100) and connected to the first output end of the heat storage unit (900); 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 third output end of the air compressor group (100) and connected to the first input end of the heat storage unit (900).

3. A liquid air energy storage device based on a reflux cold storage cycle according to claim 1, characterized in that: The air purification unit (200) comprises: A first adsorption tower (201) having an upper port and a lower port; a second adsorption tower (202) having an upper port and a lower port; a first air three-way valve (203), wherein a first port of the first air three-way valve (203) is connected to an upper port of the first adsorption tower (201), and a second port of the first air three-way valve (203) is connected to an upper port of the second adsorption tower (202); a second air three-way valve (204), wherein a first port of the second air three-way valve (204) is connected to a lower port of the first adsorption tower (201), and a second port of the second air three-way valve (204) is connected to a lower port of the second adsorption tower (202); a third air three-way valve (205), wherein a first port of the third air three-way valve (205) is connected to a third input end of the air compressor unit (100) as a first output end of the air purification unit (200), a second port of the third air three-way valve (205) is connected to a first input end of the cold storage unit (700) as a second output end of the air purification unit (200), and a third port of the third air three-way valve (205) is connected to a third port of the first air three-way valve (203); A precooler (206), wherein an input end of the precooler (206) serves as a first input end of the air purification unit, and an output end of the precooler (206) is connected to a third port of the second air three-way valve (204).

4. A liquid air energy storage device based on a reflux cold storage cycle according to claim 1, characterized in that: The cold box (300) comprises: An air cooler (301), wherein a first input end of the air cooler (301) is connected to a first output end of the air compressor unit (100) as a first input end of the cold box (300), and a second input end of the air cooler (301) is connected to a first output end of the cold storage unit (700) as a second input end of the cold box (300); a gas cryogenic expander (302), wherein an input end of the gas cryogenic expander (302) is connected to a first output end of the air cooler (301), and an output end of the gas cryogenic expander (302) is connected to a third input end of the air cooler (301); A liquid cryogenic expander (303), wherein an input end of the liquid cryogenic expander (303) is connected to a second output end of the air cooler (301); A low-temperature throttle valve (304), wherein an input end of the low-temperature throttle valve (304) is connected to an output end of the liquid low-temperature expander (303); a gas-liquid separator (305), wherein the input end of the gas-liquid separator (305) is connected to the output end of the low-temperature throttle valve (304), the first output end of the gas-liquid separator (305) is connected to the third input end of the air cooler (301), and the second output end of the gas-liquid separator (305) is connected to the first input end of the liquid air storage tank (400) as the second output end of the cold box (300); a second circulating gas three-way valve (306), wherein a first input end of the second circulating gas three-way valve (306) is connected to a third output end of the air cooler (301), and a second input end of the second circulating gas three-way valve (306) is connected to a fourth output end of the air cooler (301); A first circulation fan (307), wherein an input end of the first circulation fan (307) is connected to an output end of the second circulation gas three-way valve (306), and an output end of the first circulation fan (307) is connected to a fourth input end of the air compressor unit (100) as a first output end of the cold box.

5. The liquid air energy storage device based on the reflux cold storage cycle according to claim 1 is characterized in that: The power generation expansion unit (800) comprises: a first heater (801), wherein a first input end of the first heater (801) is connected to a first output end of the evaporator (600) as a first input end of the power generation expansion unit (800); a first power generation expander (802), wherein an input end of the first power generation expander (802) is connected to a first output end of the first heater (801); a second heater (803), wherein a first input end of the second heater (803) is connected to an output end of the first power generation expander (802); a second power-generating expander (804), wherein an input end of the second power-generating expander (804) is connected to a first output end of the second heater (803); a third heater (805), wherein a first input end of the third heater (805) is connected to an output end of the second power generation expander (804); a third power generation expander (806), wherein an input end of the third power generation expander (806) is connected to a first output end of the third heater (805); a fourth heater (807), wherein a first input end of the fourth heater (807) is connected to an output end of the third power generation expander (806); a fourth power generation expander (808), wherein the input end of the fourth power generation expander (808) is connected to the first output end of the fourth heater (807), and the output end of the fourth power generation expander (808) is connected to the third input end of the cold storage unit (700) as the first output end of the power generation expander group (800); The second input end of the first heater (801), the second input end of the second heater (803), the second input end of the third heater (805), and the second input end of the fourth heater (807) are connected in parallel as the second input end of the power generation expansion unit (800) and connected to the second output end of the heat storage unit (900); the second output end of the first heater (801), the second output end of the second heater (803), the second output end of the third heater (805), and the second output end of the fourth heater (807) are connected in parallel as the second output end of the power generation expansion unit (800) and connected to the second input end of the heat storage unit (900).

6. A liquid air energy storage device based on a reflux cold storage cycle according to claim 1, characterized in that: The cold storage unit (700) comprises: A solid cold storage packed bed (701) having an upper port and a lower port; a first cold fluid three-way valve (702), wherein a first port of the first cold fluid three-way valve (702) is connected to an upper port of the solid cold storage packed bed (701), and a second port of the first cold fluid three-way valve (702) is connected as a first input end of the cold storage unit (700); a second cold fluid three-way valve (703), wherein a first port of the second cold fluid three-way valve (703) is connected to a lower port of the solid cold storage packed bed (701), and a second port of the second cold fluid three-way valve (703) is connected to a second output end of the evaporator (600); A filter (704), wherein an input end of the filter (704) is connected to the third port of the second cold fluid three-way valve (703), and an output end of the filter (704) is connected to the second input end of the cold box (300) as a first output end of the cold storage unit (700); a third cold fluid three-way valve (705), wherein a first port of the third cold fluid three-way valve (705) is connected to a third port of the first cold fluid three-way valve (702), and a second port of the third cold fluid three-way valve (705) is connected to the external environment; a second circulation fan (706), wherein an input end of the second circulation fan (706) is connected to a third port of the third cold fluid three-way valve (705); A fourth cold fluid three-way valve (707), wherein the first port of the fourth cold fluid three-way valve (707) is connected to the output end of the second circulating fan (706), the second port of the fourth cold fluid three-way valve (707) is connected to the first output end of the power generation expansion unit (800) as the third input end of the cold storage unit (700), and the third port of the fourth cold fluid three-way valve (707) is connected to the second input end of the evaporator (600) as the second output end of the cold storage unit (700).

7. A liquid air energy storage device based on a reflux cold storage cycle according to claim 1, characterized in that: The heat storage unit (900) comprises: A normal temperature water tank (901) having an upper port and a lower port, wherein the lower port is connected to the second output end of the power generation expansion unit (800) as a second input end of the heat storage unit (900); a first circulating water pump (902), wherein an input end of the first circulating water pump (902) is connected to an upper port of the normal temperature water tank (901), and an output end of the first circulating water pump (902) is connected to a second input end of the air compressor unit (100) as a first output end of the heat storage unit (900); A hot water tank (903) having an upper port and a lower port, the upper port serving as a first input end of the heat storage unit (900) and connected to a third output end of the air compressor unit (100); A second circulating water pump (904), wherein the input end of the second circulating water pump (904) is connected to the lower port of the hot water tank (903), and the output end of the second circulating water pump (904) is connected to the second input end of the power generation expansion unit (800) as the second output end of the heat storage unit (900).

8. A liquid air energy storage method based on a reflux cold storage cycle, characterized in that: The method is implemented using a liquid air energy storage device based on a reflux cold storage cycle as described in any one of claims 1 to 7, comprising: Air liquefaction cycle process: after being initially compressed by a first compressor (101) and a second compressor (103) and cooled by a first cooler (102) and a second cooler (104), the ambient air enters an air purification unit (200) to remove water, carbon dioxide, and alkane components in the air, and then is further compressed to a high pressure by a third compressor (105) and a fourth compressor (107). At the same time, a heat exchange fluid is used to recover the compression heat generated in the air compression process and store it in a heat storage unit (900); the high-pressure air output by the air compressor unit (100) enters a cold box (300) to be cooled to a liquid state and stored in a liquid air storage tank (400), and a circulating gas from the air purification unit (200) carries out the cold energy in the solid cold storage packed bed (701) to increase the air liquefaction rate; Air power generation cycle process: the liquid air output from the liquid air storage tank (400) is pressurized to high pressure by a low-temperature liquid pump (500), and then enters the evaporator (600) to undergo a liquid-gas phase change process, and the phase change cold energy is recovered and stored in the cold storage unit (700) through the outflow gas of the power generation expansion unit (800); the vaporized high-pressure air enters the power generation expansion unit (800), is heated to high temperature by a part of the compression heat stored in the heat storage unit (900), and then expands to generate electricity.

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