A Liquid Air Energy Storage Device and Method Based on a Reflux Cold Energy Storage Cycle

Abstract

The present invention relates to the technical field of liquid air energy storage, and particularly to a liquid air energy storage device and method based on a reflux cold energy storage cycle, including an air liquefaction cycle loop and an air power generation cycle loop; the air liquefaction cycle loop includes an air compressor unit, an air purification unit, a cold box, a liquid air storage tank, a cold energy storage unit and a heat storage unit. During the low electricity consumption period, the ambient air is purified, compressed and cooled, and then expands and depressurizes to obtain liquid air. At the same time, the compressed air thermal energy is recovered and stored, and the cold energy of the cold energy storage unit is reused through a circulating gas discharged from the air purification unit to enhance the liquefaction performance. During the high electricity consumption period, the liquid air is pressurized, evaporated and vaporized and heated, and then enters the power generation expansion unit to generate electricity, and the evaporation and vaporization cold energy is recovered and stored by using the gas at the outlet of the power generation expansion machine. The present invention improves the cold energy recovery and storage efficiency of the solid cold energy storage packed bed through the structural form of the reflux cold energy storage cycle, and effectively distributes and utilizes the compressed air thermal energy.

Description

Technical Field

[0001] The present invention relates to the technical field of liquid air energy storage, and in particular to a liquid air energy storage 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 more and more experts and scholars due to its advantages such as being not restricted by geographical conditions, having a large energy storage density, and being environmentally friendly. The liquid air energy storage system uses liquid air or nitrogen as the "electricity storage medium" and also includes complex heat storage and cold storage processes. Its basic operating principle is as follows: Excess electricity from the power grid drives the compressor to work, performing the air liquefaction process, storing the electricity in the form of liquid air, and storing the compression heat; when power needs to be supplied to the outside world, the liquid air is pressurized by a cryogenic pump and the low-temperature cold energy is recovered, and then drives the air power generation expander to do work and generate electricity.

[0003] In the liquid air energy storage system, the recovery and utilization of the low-temperature cold energy during the vaporization process of liquid air is the key to improving the cycle power generation efficiency of the system. The solid cold storage packed bed is a cold storage structure most recognized in the industry. The pipeline connects the cold box and the evaporator, and usually includes a closed-loop cold charging process and a cold releasing process. However, in the closed-loop cycle, it is difficult to completely extract the cold energy in the bed body, and at the same time, the flow of the heat transfer fluid also requires a blower to provide positive pressure to overcome the transmission resistance, thus consuming a large amount of electricity. Summary of the Invention

[0004] The purpose of the present invention is to solve the deficiencies existing in the prior art, and to 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 during the air power generation process and the reflux gas during the air liquefaction process as the heat transfer fluid for the cold charging and cold releasing processes of the cold storage unit respectively. The invention simplifies the system structure, avoids problems such as air replenishment during pressure fluctuations in the closed-loop cycle, improves the energy utilization rate of the cold storage unit, and finally improves the cycle power generation efficiency of the system.

[0005] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0006] 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;

[0007] The air liquefaction cycle 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;

[0008] The first input end of the air compressor unit is used to input ambient air. The first output end of the air compressor unit is connected to the first input end of the cold box. The second output end of the air compressor unit is connected to the first input end of the air purification unit. The third output end of the air compressor unit is connected to the first input end of the heat storage unit. The second input end of the air compressor unit is connected to the first output end of the heat storage unit. The third input end of the air compressor unit is connected to the first output end of the air purification unit. The fourth input end of the air compressor unit is connected to the first output end of the cold box;

[0009] The second output end of the air purification unit is connected to the first input end of the cold storage unit;

[0010] The second input end of the cold box is connected to the first output end of the cold storage unit. The second output end of the cold box is connected to the first input end of the liquid air storage tank;

[0011] The air power generation cycle circuit 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;

[0012] The input end of the cryogenic liquid pump is connected to the output end of the liquid air storage tank. The output end of the cryogenic liquid pump is connected to the first input end of the evaporator;

[0013] 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. The second input end of the evaporator is connected to the second output end of the cold storage unit;

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

[0015] The air liquefaction cycle circuit is used to purify, compress, and cool ambient air and then expand and depressurize it to obtain liquid air. The liquid air is transported to the air power generation cycle circuit, and the air compression heat generated during the compression process is stored in the heat storage unit;

[0016] The air power generation cycle circuit expands and generates electricity after pressurizing, evaporating and vaporizing, and further heating the received liquid air. The cold energy generated during the vaporization process of the liquid air is stored in the cold storage unit.

[0017] Preferably, the air compressor unit includes:

[0018] The first compressor, the input end of the first compressor being the first input end of the air compressor unit;

[0019] The first cooler, the first input end of the first cooler being connected to the output end of the first compressor;

[0020] The second compressor, the input end of the second compressor being connected to the first output end of the first cooler;

[0021] The second cooler, the first input end of the second cooler being connected to the output end of the second compressor, and the first output end of the second cooler being the second output end of the air compressor unit and being connected to the first input end of the air purification unit;

[0022] The first recycle gas three-way valve, the first port of the first recycle gas three-way valve being the third input end of the air compressor unit and being connected to the first output end of the air purification unit, and the second port of the first recycle gas three-way valve being the fourth input end of the air compressor unit and being connected to the first output end of the cold box;

[0023] The third compressor, the input end of the third compressor being connected to the third port of the first recycle gas three-way valve;

[0024] The third cooler, the first input end of the third cooler being connected to the output end of the third compressor;

[0025] The fourth compressor, the input end of the fourth compressor being connected to the first output end of the third cooler;

[0026] The fourth cooler, the first input end of the fourth cooler being connected to the output end of the fourth compressor; the first output end of the fourth cooler being the first output end of the air compressor unit and being connected to the first input end of the cold box;

[0027] The second input ends of the first cooler, the second cooler, the third cooler, and the fourth cooler are connected in parallel as the second input end of the air compressor unit and are connected to the first output end of the heat storage unit; the second output ends of the first cooler, the second cooler, the third cooler, and the fourth cooler are connected in parallel as the third output end of the air compressor unit and are connected to the first input end of the heat storage unit.

[0028] Preferably, the air purification unit includes:

[0029] The first adsorption tower, which has an upper port and a lower port;

[0030] The second adsorption tower, which has an upper port and a lower port;

[0031] A first air three-way valve, the first port of the first air three-way valve is connected to the upper port of the first adsorption tower, and the second port of the first air three-way valve is connected to the upper port of the second adsorption tower;

[0032] A second air three-way valve, the first port of the second air three-way valve is connected to the lower port of the first adsorption tower, and the second port of the second air three-way valve is connected to the lower port of the second adsorption tower;

[0033] A third air three-way valve, the first port of the third air three-way valve serves as the first output end of the air purification unit and is connected to the third input end of the air compressor unit, the second port of the third air three-way valve serves as the second output end of the air purification unit and is connected to the first input end of the cold storage 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;

[0034] A precooler, the input end of the precooler serves as the first input end of the air purification unit, and the output end of the precooler is connected to the third port of the second air three-way valve.

[0035] Preferably, the cold box includes:

[0036] An air cooler, the first input end of the air cooler serves as the first input end of the cold box and is connected to the first output end of the air compressor unit, and the second input end of the air cooler serves as the second input end of the cold box and is connected to the first output end of the cold storage unit;

[0037] A gas cryogenic expander, the input end of the gas cryogenic expander is connected to the first output end of the air cooler, and the output end of the gas cryogenic expander is connected to the third input end of the air cooler;

[0038] A liquid cryogenic expander, the input end of the liquid cryogenic expander is connected to the second output end of the air cooler;

[0039] A cryogenic throttle valve, the input end of the cryogenic throttle valve is connected to the output end of the liquid cryogenic expander;

[0040] A gas-liquid separator, the input end of the gas-liquid separator is connected to the output end of the cryogenic 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 serves as the second output end of the cold box and is connected to the first input end of the liquid air storage tank;

[0041] The second recycle gas three-way valve, the first input end of the second recycle gas three-way valve is connected to the third output end of the air cooler, and the second input end of the second recycle gas three-way valve is connected to the fourth output end of the air cooler;

[0042] The first recycle fan, the input end of the first recycle fan is connected to the output end of the second recycle gas three-way valve, and the output end of the first recycle fan serves as the first output end of the cold box and is connected to the fourth input end of the air compressor unit.

[0043] Preferably, the power generation expansion unit includes:

[0044] The first heater, the first input end of the first heater serves as the first input end of the power generation expansion unit and is connected to the first output end of the evaporator;

[0045] The first power generation expander, the input end of the first power generation expander is connected to the first output end of the first heater;

[0046] The second heater, the first input end of the second heater is connected to the output end of the first power generation expander;

[0047] The second power generation expander, the input end of the second power generation expander is connected to the first output end of the second heater;

[0048] The third heater, the first input end of the third heater is connected to the output end of the second power generation expander;

[0049] The third power generation expander, the input end of the third power generation expander is connected to the first output end of the third heater;

[0050] The fourth heater, the first input end of the fourth heater is connected to the output end of the third power generation expander;

[0051] The fourth power generation expander, the input end of the fourth power generation expander is connected to the first output end of the fourth heater, and the output end of the fourth power generation expander serves as the first output end of the power generation expansion unit and is connected to the third input end of the cold storage unit;

[0052] The second input ends of the first heater, the second heater, the third heater, and 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 ends of the first heater, the second heater, the third heater, and 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.

[0053] Preferably, the cold storage unit includes:

[0054] A solid cold storage packed bed having an upper port and a lower port;

[0055] A first cold fluid three-way valve, wherein a first port of the first cold fluid three-way valve is connected to the 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 the cold storage unit;

[0056] A second cold fluid three-way valve, wherein a first port of the second cold fluid three-way valve is connected to the 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;

[0057] A filter, wherein an input end of the filter is connected to a third port of the second cold fluid three-way valve, and an output end of the filter is connected as a first output end of the cold storage unit to a second input end of the cold box;

[0058] 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 the external environment;

[0059] 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;

[0060] A fourth cold fluid three-way valve, wherein a first port of the fourth cold fluid three-way valve is connected to an output end of the second circulation fan, a second port of the fourth cold fluid three-way valve is connected as a third input end of the cold storage unit to a first output end of the power generation expansion unit, and a third port of the fourth cold fluid three-way valve is connected as a second output end of the cold storage unit to a second input end of the evaporator.

[0061] Preferably, the heat storage unit includes:

[0062] A normal temperature water tank having an upper port and a lower port, and the lower port is connected as a second input end of the heat storage unit to a second output end of the power generation expansion unit;

[0063] A first circulation water pump, wherein an input end of the first circulation water pump is connected to the upper port of the normal temperature water tank, and an output end of the first circulation water pump is connected as a first output end of the heat storage unit to a second input end of the air compressor unit;

[0064] A hot water tank having an upper port and a lower port, and the upper port is connected as a first input end of the heat storage unit to a third output end of the air compressor unit;

[0065] 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.

[0066] 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:

[0067] 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;

[0068] 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.

[0069] 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.

[0070] 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.

[0071] Compared with the prior art, the present invention has the following beneficial effects:

[0072] 1. The present invention adopts a reflux cold storage cycle structure, which effectively simplifies system control and makes the operation strategy simpler.

[0073] 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.

[0074] 3. The present invention can effectively improve the exergy efficiency of the cold storage unit, thereby enhancing the power generation efficiency of the liquid air energy storage system. BRIEF DESCRIPTION OF THE DRAWINGS

[0075] Figure 1 is a schematic structural diagram of the present invention;

[0076] Figure 2 is a schematic structural diagram of the air purification unit in the present invention;

[0077] Figure 3 is a schematic structural diagram of the cold box in the present invention;

[0078] Figure 4 is a schematic structural diagram of the cold storage unit in the present invention.

[0079] 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 low-temperature expander, 303 liquid low-temperature expander, 304 low-temperature throttle valve, 305 gas-liquid separator, 306 second circulating gas three-way valve, 307 first circulating fan, 400 liquid air storage tank, 500 low-temperature 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 expander unit, 801 first heater, 802 first power generation expander, 803 second heater, 804 second power generation expander, 805 third heater, 806 third power generation expander, 807 fourth heater, 808 fourth power generation expander, 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 OF THE EMBODIMENTS

[0080] The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings, so that those skilled in the art can better understand the advantages and features of the present invention, and thus more clearly define the protection scope of the present invention. The embodiments described herein are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0081] 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;

[0082] The air liquefaction cycle 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;

[0083] 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. The fourth input end of the air compressor unit 100 is connected to the first output end of the cold box 300;

[0084] The second output end of the air purification unit 200 is connected to the first input end of the cold storage unit 700;

[0085] The second input end of the cold box 300 is connected to the first output end of the cold storage unit 700. The second output end of the cold box 300 is connected to the first input end of the liquid air storage tank 400;

[0086] 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;

[0087] The input end of the cryogenic liquid pump 500 is connected to the output end of the liquid air storage tank 400. The output end of the cryogenic liquid pump 500 is connected to the first input end of the evaporator 600;

[0088] 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. The second input end of the evaporator 600 is connected to the second output end of the cold storage unit 700;

[0089] 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;

[0090] The air liquefaction cycle loop is used to purify, compress and cool ambient air and then expand and depressurize it to obtain liquid air. The liquid air is transmitted to the air power generation cycle loop, and the air compression heat generated during the compression process is stored in the heat storage unit 900;

[0091] The air power generation cycle loop expands and generates electricity after pressurizing, evaporating and further heating the received liquid air, and the cold energy generated during the vaporization process of the liquid air is stored in the cold storage unit 700.

[0092] Specifically, the air compressor unit 100 includes:

[0093] A first compressor 101, and the input end of the first compressor 101 serves as the first input end of the air compressor unit 100;

[0094] A first cooler 102, and the first input end of the first cooler 102 is connected to the output end of the first compressor 101;

[0095] A second compressor 103, and the input end of the second compressor 103 is connected to the first output end of the first cooler 102;

[0096] A second cooler 104, the first input end of the second cooler 104 is connected to the output end of the second compressor 103, and the first output end of the second cooler 104 serves as the second output end of the air compressor unit 100 and is connected to the first input end of the air purification unit 200;

[0097] A first circulating gas three-way valve 109, the first port of the first circulating gas three-way valve 109 serves as the third input end of the air compressor unit 100 and is connected to the first output end of the air purification unit 200, and the second port of the first circulating gas three-way valve 109 serves as the fourth input end of the air compressor unit 100 and is connected to the first output end of the cold box 300;

[0098] A third compressor 105, and the input end of the third compressor 105 is connected to the third port of the first circulating gas three-way valve 109;

[0099] A third cooler 106, and the first input end of the third cooler 106 is connected to the output end of the third compressor 105;

[0100] The fourth compressor 107, the input end of the fourth compressor 107 is connected to the first output end of the third cooler 106;

[0101] The fourth cooler 108, the first input end of the fourth cooler 108 is connected to the output end of the fourth compressor 107; the first output end of the fourth cooler 108 serves as the first output end of the air compressor unit 100 and is connected to the first input end of the cold box 300;

[0102] The second input ends of the first cooler 102, the second cooler 104, the third cooler 106, and the fourth cooler 108 are connected in parallel as the second input end of the air compressor unit 100 and are connected to the first output end of the heat storage unit 900; the second output ends of the first cooler 102, the second cooler 104, the third cooler 106, and the fourth cooler 108 are connected in parallel as the third output end of the air compressor unit 100 and are connected to the first input end of the heat storage unit 900.

[0103] Specifically, the air purification unit 200 includes:

[0104] The first adsorption tower 201, which has an upper port and a lower port;

[0105] The second adsorption tower 202, which has an upper port and a lower port;

[0106] The first air three-way valve 203, the first port of the first air three-way valve 203 is connected to the upper port of the first adsorption tower 201, and the second port of the first air three-way valve 203 is connected to the upper port of the second adsorption tower 202;

[0107] The second air three-way valve 204, the first port of the second air three-way valve 204 is connected to the lower port of the first adsorption tower 201, and the second port of the second air three-way valve 204 is connected to the lower port of the second adsorption tower 202;

[0108] The third air three-way valve 205, the first port of the third air three-way valve 205 serves as the first output end of the air purification unit 200 and is connected to the third input end of the air compressor unit 100, the second port of the third air three-way valve 205 serves as the second output end of the air purification unit 200 and is connected to the first input end of the cold storage unit 700, and the third port of the third air three-way valve 205 is connected to the third port of the first air three-way valve 203;

[0109] A precooler 206, the input end of the precooler 206 being the first input end of the air purification unit, and the output end of the precooler 206 being connected to the third port of the second air three-way valve 204.

[0110] Specifically, the cold box 300 includes:

[0111] An air cooler 301, the first input end of the air cooler 301 being the first input end of the cold box 300 and being connected to the first output end of the air compressor unit 100, and the second input end of the air cooler 301 being the second input end of the cold box 300 and being connected to the first output end of the cold storage unit 700;

[0112] A gas cryogenic expander 302, the input end of the gas cryogenic expander 302 being connected to the first output end of the air cooler 301, and the output end of the gas cryogenic expander 302 being connected to the third input end of the air cooler 301;

[0113] A liquid cryogenic expander 303, the input end of the liquid cryogenic expander 303 being connected to the second output end of the air cooler 301;

[0114] A cryogenic throttle valve 304, the input end of the cryogenic throttle valve 304 being connected to the output end of the liquid cryogenic expander 303;

[0115] A gas-liquid separator 305, the input end of the gas-liquid separator 305 being connected to the output end of the cryogenic throttle valve 304, the first output end of the gas-liquid separator 305 being connected to the third input end of the air cooler 301, and the second output end of the gas-liquid separator 305 being the second output end of the cold box 300 and being connected to the first input end of the liquid air storage tank 400;

[0116] A second recycle gas three-way valve 306, the first input end of the second recycle gas three-way valve 306 being connected to the third output end of the air cooler 301, and the second input end of the second recycle gas three-way valve 306 being connected to the fourth output end of the air cooler 301;

[0117] A first recycle fan 307, the input end of the first recycle fan 307 being connected to the output end of the second recycle gas three-way valve 306, and the output end of the first recycle fan 307 being the first output end of the cold box and being connected to the fourth input end of the air compressor unit 100.

[0118] Specifically, the power generation expander unit 800 includes:

[0119] The first heater 801, the first input end of the first heater 801 is connected to the first output end of the evaporator 600 as the first input end of the power generation expansion unit 800;

[0120] The first power generation expansion machine 802, the input end of the first power generation expansion machine 802 is connected to the first output end of the first heater 801;

[0121] The second heater 803, the first input end of the second heater 803 is connected to the output end of the first power generation expansion machine 802;

[0122] The second power generation expansion machine 804, the input end of the second power generation expansion machine 804 is connected to the first output end of the second heater 803;

[0123] The third heater 805, the first input end of the third heater 805 is connected to the output end of the second power generation expansion machine 804;

[0124] The third power generation expansion machine 806, the input end of the third power generation expansion machine 806 is connected to the first output end of the third heater 805;

[0125] The fourth heater 807, the first input end of the fourth heater 807 is connected to the output end of the third power generation expansion machine 806;

[0126] The fourth power generation expansion machine 808, the input end of the fourth power generation expansion machine 808 is connected to the first output end of the fourth heater 807, and the output end of the fourth power generation expansion machine 808 is used as the first output end of the power generation expansion unit 800 and is connected to the third input end of the cold storage unit 700;

[0127] The second input ends of the first heater 801, the second heater 803, the third heater 805 and 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 ends of the first heater 801, the second heater 803, the third heater 805 and 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.

[0128] Specifically, the cold storage unit 700 includes:

[0129] The solid cold storage packed bed 701, which has an upper port and a lower port;

[0130] The first cold fluid three-way valve 702, the first port of the first cold fluid three-way valve 702 is connected to the upper port of the solid cold storage packed bed 701, and the second port of the first cold fluid three-way valve 702 is connected as the first input end of the cold storage unit 700;

[0131] The second cold fluid three-way valve 703, the first port of the second cold fluid three-way valve 703 is connected to the lower port of the solid cold storage packed bed 701, and the second port of the second cold fluid three-way valve 703 is connected to the second output end of the evaporator 600;

[0132] The filter 704, 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 as the first output end of the cold storage unit 700 to the second input end of the cold box 300;

[0133] The third cold fluid three-way valve 705, the first port of the third cold fluid three-way valve 705 is connected to the third port of the first cold fluid three-way valve 702, and the second port of the third cold fluid three-way valve 705 is connected to the external environment;

[0134] The second circulation fan 706, the input end of the second circulation fan 706 is connected to the third port of the third cold fluid three-way valve 705;

[0135] The fourth cold fluid three-way valve 707, 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 as the third input end of the cold storage unit 700 to the first output end of the power generation expansion unit 800, and the third port of the fourth cold fluid three-way valve 707 is connected as the second output end of the cold storage unit 700 to the second input end of the evaporator 600.

[0136] Specifically, the heat storage unit 900 includes:

[0137] The normal temperature water tank 901, which has an upper port and a lower port, and the lower port is connected as the second input end of the heat storage unit 900 to the second output end of the power generation expansion unit 800;

[0138] The first circulation water pump 902, the input end of the first circulation water pump 902 is connected to the upper port of the normal temperature water tank 901, and the output end of the first circulation water pump 902 is connected as the first output end of the heat storage unit 900 to the second input end of the air compressor unit 100;

[0139] The hot water tank 903, which has an upper port and a lower port, and the upper port is connected as the first input end of the heat storage unit 900 to the third output end of the air compressor unit 100;

[0140] 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 .

[0141] 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:

[0142] 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;

[0143] 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.

[0144] 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.

[0145] 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.

[0146] In order to further illustrate the embodiments of the present invention, Figure 1The liquid air energy storage system based on the reflux cold storage cycle shown in the figure was simulated. The cold storage unit adopted the form of a solid cold storage packed bed, and the heat storage unit adopted the form of a pressurized water tank. Table 1 shows the parameters of each key point in the system operation. Considering a cold storage exergy efficiency of 95%, the liquefaction rate of the system is 57%, and the cycle power generation efficiency of the system is 58.2%. In the liquid air energy storage systems of the same 50 MW level, the reflux and closed cold storage structures were studied and compared. 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 the closed cold storage.

[0147]

[0148]

[0149]

[0150] 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 allocates and utilizes the air compression heat energy, which is a high-efficiency and low-cost liquid air energy storage technology.

[0151] The descriptions and practices disclosed in the present invention are easy to think about and understand for ordinary technicians in the technical field. Without departing from the principle of the present invention, several improvements and refinements can also be made. Therefore, the modifications or improvements made without departing from the spirit of the present invention should also be regarded as within 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. A liquid air energy storage device based on a reflux cold storage cycle according to claim 1, 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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