Liquid air energy storage power generation device and method based on packed bed step cold storage

Abstract

The present application relates to the technical fields of liquid air energy storage and cold energy storage, and particularly relates to a liquid air energy storage power generation device and method based on packed bed stepwise cold storage, comprising a liquid air supply unit, a cold energy stepwise storage and recovery unit and an air expansion power generation unit. After being pressurized by a cryogenic pump, the liquid air enters the cold energy stepwise storage and recovery unit, releases cold energy through graded vaporization, and the vaporized air enters the air expansion power generation unit to generate power. The air with residual pressure after power generation enters the cold energy stepwise storage and recovery unit as a heat exchange fluid, recovers low-temperature cold energy through grading and stores the cold energy through grading. Through graded heat exchange and stepwise cold storage, the present application reduces the heat exchange temperature difference, reduces the temperature gradient of the packed bed, and further reduces the cold energy loss in the heat exchange and cold storage process, thereby improving the system efficiency. In addition, the present application uses the residual pressure after air power generation as the driving force, and does not need an additional circulating fan, thereby reducing the investment cost.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of liquid air energy storage and cold energy storage, and particularly relates to a liquid air energy storage power generation device and method based on filling bed cascade cold storage. BACKGROUND

[0002] Liquid air energy storage is one of the effective energy storage technologies for the imbalance between power supply and demand. During the low electricity consumption period (charging process), the system inputs electric energy to liquefy air, so that the electric energy is stored in the form of liquid air; during the peak electricity consumption period (discharging process), the liquid air drives the expansion generator after processes such as pressurization and heating to output electric energy. Liquid air energy storage has the characteristics of high energy storage density, short response time, environmental friendliness, low levelized cost of energy storage (LCOE), and no geographical condition limitation, and has attracted widespread attention.

[0003] During the operation of the liquid air energy storage, efficient cold storage of the liquid air evaporation cold energy in the power generation process is the key to improving the thermodynamics and economy of the system. The cold storage filling bed is a conventional cold storage form for the liquid air energy storage system. The traditional cold storage filling bed has low cold energy recovery and storage efficiency due to the large heat exchange temperature difference on the system loop heat exchanger side, the wide bed heat exchange / cold storage temperature range, and the like. Moreover, the conventional cold storage filling bed needs an independent fan to provide power, and has large power consumption. SUMMARY

[0004] The present application aims at solving the problems in the prior art, and provides a liquid air energy storage power generation device and method based on filling bed cascade cold storage. The device and method reduce the heat exchange temperature difference, reduce the filling bed temperature gradient, and thus reduce the cold energy loss in the heat exchange and cold storage processes, and improve the system efficiency through the staged heat exchange and cascade cold storage. In addition, the device and method use the residual pressure after air power generation as the driving force, do not need an additional circulating fan, and can reduce the investment cost.

[0005] In order to achieve the above-mentioned purpose, the present application adopts the following technical scheme:

[0006] A liquid air energy storage power generation device based on filling bed cascade cold storage comprises a liquid air supply unit, a cold energy cascade storage unit, and an air expansion power generation unit. The liquid air supply unit is connected with the cold energy cascade storage unit, and the cold energy cascade storage unit is connected with the air expansion power generation unit.

[0007] The liquid air in the liquid air supply unit can be derived from the liquid air energy storage charging process during the low electricity consumption period. The liquid air supply unit is used to provide air medium and power for the liquid air power generation process, and the pressurized liquid air is transmitted to the cold energy cascade storage unit.

[0008] The cold energy cascade storage unit will receive the liquid air and vaporize it in stages, storing the vaporization cold energy, and transmitting the vaporized air to the air expansion power generation unit;

[0009] The air expansion power generation unit will receive the gaseous air and heat it to send it to the expansion power generator to generate power, and will transmit the discharged air with residual pressure as a heat transfer fluid to the cold energy cascade storage unit to participate in the recovery and storage of liquid air cold energy; the air will be finally discharged to the outside by the cold energy cascade storage unit.

[0010] Preferably, the liquid air supply unit includes a liquid air storage tank and a cryogenic pump; the liquid air input of the liquid air storage tank can be sourced from the liquid air energy storage charging process during the off-peak electricity period, the output end of the liquid air storage tank is connected with the input end of the cryogenic pump; the output end of the cryogenic pump is connected with the first input end of the cold energy cascade storage unit as the output end of the liquid air supply unit.

[0011] Preferably, the cold energy cascade storage unit includes a first heat exchanger, a second heat exchanger, a third heat exchanger, a fourth heat exchanger, a first cold storage packed bed, a second cold storage packed bed, a third cold storage packed bed, a fourth cold storage packed bed, a fifth cold storage packed bed, a sixth cold storage packed bed and a seventh cold storage packed bed.

[0012] The first input end of the first heat exchanger is connected with the output end of the liquid air supply unit as the first input end of the cold energy cascade storage unit, the first output end of the first heat exchanger is connected with the first input end of the second heat exchanger; the first output end of the second heat exchanger is connected with the first input end of the third heat exchanger; the first output end of the third heat exchanger is connected with the first input end of the fourth heat exchanger; the first output end of the fourth heat exchanger is connected with the input end of the air expansion power generation unit as the first output end of the cold energy cascade storage unit.

[0013] The second input end of the fourth heat exchanger is connected with the output end of the air expansion power generation unit as the second input end of the cold energy step-by-step storage unit, and the second output end of the fourth heat exchanger is connected with the input end of the first cold storage packed bed; the output end of the first cold storage packed bed is connected with the second input end of the third heat exchanger; the second output end of the third heat exchanger is connected with the input end of the second cold storage packed bed; the output end of the second cold storage packed bed is connected with the second input end of the second heat exchanger; the second output end of the second heat exchanger is connected with the input end of the third cold storage packed bed; the output end of the third cold storage packed bed is connected with the second input end of the first heat exchanger; the second output end of the first heat exchanger is connected with the input end of the fourth cold storage packed bed; the output end of the fourth cold storage packed bed is connected with the input end of the fifth cold storage packed bed; the output end of the fifth cold storage packed bed is connected with the input end of the sixth cold storage packed bed; the output end of the sixth cold storage packed bed is connected with the input end of the seventh cold storage packed bed; and the output end of the seventh cold storage packed bed is connected with the environment as the second output end of the cold energy step-by-step storage unit.

[0014] Preferably, the air expansion power generation unit comprises a fifth heat exchanger, a first expansion generator, a sixth heat exchanger, a second expansion generator, a seventh heat exchanger, a third expansion generator, an eighth heat exchanger and a fourth expansion generator.

[0015] The input end of the fifth heat exchanger is connected with the first output end of the cold energy step-by-step storage unit as the input end of the air expansion power generation unit; the output end of the fifth heat exchanger is connected with the input end of the first expansion generator; the output end of the first expansion generator is connected with the input end of the sixth heat exchanger; the output end of the sixth heat exchanger is connected with the input end of the second expansion generator; the output end of the second expansion generator is connected with the input end of the seventh heat exchanger; the output end of the seventh heat exchanger is connected with the input end of the third expansion generator; the output end of the third expansion generator is connected with the input end of the eighth heat exchanger; the output end of the eighth heat exchanger is connected with the input end of the fourth expansion generator; and the output end of the fourth expansion generator is connected with the second input end of the cold energy step-by-step storage unit as the output end of the air expansion power generation unit.

[0016] The application further provides a liquid air energy storage power generation method based on packed bed step-by-step cold storage, which is realized based on the liquid air energy storage power generation device based on packed bed step-by-step cold storage.

[0017] Liquid air flows out from a liquid air tank, is pumped by a cryogenic pump to provide circulating power, and is pumped to a first heat exchanger, a second heat exchanger, a third heat exchanger and a fourth heat exchanger for stage vaporization; the vaporized air enters an air expansion power generation unit for multi-stage heating and expansion power generation; the expanded air with residual pressure enters a cold energy stage storage unit as a heat exchange fluid to heat liquid air in stages and recover vaporization cold energy to a first cold storage packed bed, a second cold storage packed bed, a third cold storage packed bed, a fourth cold storage packed bed, a fifth cold storage packed bed, a sixth cold storage packed bed and a seventh cold storage packed bed for stage storage; and finally the air is discharged from the seventh cold storage packed bed into the environment.

[0018] Preferably, the vaporization cold energy of the liquid air is stored in stages in the plurality of cold storage packed beds, wherein the first cold storage packed bed and the seventh cold storage packed bed store low-grade cold energy, the second cold storage packed bed and the sixth cold storage packed bed store medium-grade cold energy, the third cold storage packed bed and the fifth cold storage packed bed store medium-high-grade cold energy, and the fourth cold storage packed bed stores high-grade cold energy.

[0019] Compared with the prior art, the present application has the following beneficial effects:

[0020] 1. The present application uses stage heat exchange to reduce the heat exchange temperature difference of the heat exchanger for vaporizing liquid air in the power generation process, realizes small-temperature-difference heat exchange of the heat exchanger, and reduces the cold energy loss in the heat exchanger.

[0021] 2. The present application uses stage cold storage to reduce the storage temperature gradient of the cold storage packed bed, avoids mixing of cold energy of different energy levels in the storage stage, and reduces the cold energy loss in the cold storage packed bed.

[0022] 3. The present application uses the residual pressure after air power generation as a driving force, does not need an additional circulating fan, and can reduce investment cost. BRIEF DESCRIPTION OF DRAWINGS

[0023] Figure 1 Fig. 1 is a structural schematic diagram of the power generation device of the present application.

[0024] In the figure: 100 is a liquid air supply unit, 101 is a liquid air tank, and 102 is a cryogenic pump; 200 is a cold energy stage storage unit, 201 is a first heat exchanger, 202 is a second heat exchanger, 203 is a third heat exchanger, and 204 is a fourth heat exchanger; 205 is a first cold storage packed bed, 206 is a second cold storage packed bed, 207 is a third cold storage packed bed, 208 is a fourth cold storage packed bed, 209 is a fifth cold storage packed bed, 2010 is a sixth cold storage packed bed, and 2011 is a seventh cold storage packed bed; 300 is an air expansion power generation unit, 301 is a fifth heat exchanger, 302 is a first expansion power generator, 303 is a sixth heat exchanger, 304 is a second expansion power generator, 305 is a seventh heat exchanger, 306 is a third expansion power generator, 307 is an eighth heat exchanger, and 308 is a fourth expansion power generator. DETAILED DESCRIPTION

[0025] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings, so that the person skilled in the art can better understand the advantages and features of the present application, and the protection scope of the present application can be more clearly defined. The described embodiments of the present application are only some of the embodiments of the present application, but not all the embodiments. Based on the embodiments of the present application, all other embodiments obtained by the person skilled in the art without creative work are within the protection scope of the present application.

[0026] A liquid air energy storage and generation device based on packed bed stepwise cold storage, comprising a liquid air supply unit, a cold energy stepwise storage unit and an air expansion power generation unit; the liquid air supply unit is connected with the cold energy stepwise storage unit, and the cold energy stepwise storage unit is connected with the air expansion power generation unit.

[0027] The liquid air in the liquid air supply unit 100 can be sourced from the liquid air energy storage charging process during the off-peak electricity consumption time. The liquid air supply unit 100 is used to provide air medium and power for the liquid air power generation process. The pressurized liquid air is transmitted to the cold energy stepwise storage unit 200.

[0028] The cold energy stepwise storage unit 200 grades the received liquid air and stores the graded cold energy. The vaporized air is transmitted to the air expansion power generation unit 300.

[0029] The air expansion power generation unit 300 receives the gaseous air and sends it into the expansion generator for expansion power generation after heating. The discharged air with residual pressure is used as a heat transfer fluid and is transmitted to the cold energy stepwise storage unit 200 to participate in the recovery and storage of the liquid air cold energy. The air is finally discharged to the outside by the cold energy stepwise storage unit 200.

[0030] Specifically, the liquid air supply unit 100 comprises a liquid air storage tank 101 and a cryogenic pump 102. The liquid air input of the liquid air storage tank 101 can be sourced from the liquid air energy storage charging process during the off-peak electricity consumption time. The output end of the liquid air storage tank 101 is connected with the input end of the cryogenic pump 102. The output end of the cryogenic pump 102 serves as the output end of the liquid air supply unit 100 and is connected with the first input end of the cold energy stepwise storage unit 200.

[0031] Specifically, the cold energy cascade storage unit 200 comprises a first heat exchanger 201, a second heat exchanger 202, a third heat exchanger 203, a fourth heat exchanger 204, a first cold storage packed bed 205, a second cold storage packed bed 206, a third cold storage packed bed 207, a fourth cold storage packed bed 208, a fifth cold storage packed bed 209, a sixth cold storage packed bed 2010, and a seventh cold storage packed bed 2011.

[0032] The first input end of the first heat exchanger 201 is connected with the output end of the liquid air supply unit 100 as the first input end of the cold energy cascade storage unit 200, and the first output end of the first heat exchanger 201 is connected with the first input end of the second heat exchanger 202; the first output end of the second heat exchanger 202 is connected with the first input end of the third heat exchanger 203; the first output end of the third heat exchanger 203 is connected with the first input end of the fourth heat exchanger 204; and the first output end of the fourth heat exchanger 204 is connected with the input end of the air expansion power generation unit 300 as the first output end of the cold energy cascade storage unit 200.

[0033] The second input end of the fourth heat exchanger 204 is connected with the output end of the air expansion power generation unit 300 as the second input end of the cold energy cascade storage unit 200, and the second output end of the fourth heat exchanger 204 is connected with the input end of the first cold storage packed bed 205; the output end of the first cold storage packed bed 205 is connected with the second input end of the third heat exchanger 203; the second output end of the third heat exchanger 203 is connected with the input end of the second cold storage packed bed 206; the output end of the second cold storage packed bed 206 is connected with the second input end of the second heat exchanger 202; the second output end of the second heat exchanger 202 is connected with the input end of the third cold storage packed bed 207; the output end of the third cold storage packed bed 207 is connected with the second input end of the first heat exchanger 201; the second output end of the first heat exchanger 201 is connected with the input end of the fourth cold storage packed bed 208; the output end of the fourth cold storage packed bed 208 is connected with the input end of the fifth cold storage packed bed 209; the output end of the fifth cold storage packed bed 209 is connected with the input end of the sixth cold storage packed bed 2010; the output end of the sixth cold storage packed bed 2010 is connected with the input end of the seventh cold storage packed bed 2011; and the output end of the seventh cold storage packed bed 2011 is connected with the environment as the second output end of the cold energy cascade storage unit 200.

[0034] Specifically, the air expansion power generation unit 300 comprises a fifth heat exchanger 301, a first expansion power generator 302, a sixth heat exchanger 303, a second expansion power generator 304, a seventh heat exchanger 305, a third expansion power generator 306, an eighth heat exchanger 307, and a fourth expansion power generator 308.

[0035] The input end of the fifth heat exchanger 301 is connected with the first output end of the cold energy step storage unit 200 as the input end of the air expansion power generation unit 300; the output end of the fifth heat exchanger 301 is connected with the input end of the first expansion power generator 302; the output end of the first expansion power generator 302 is connected with the input end of the sixth heat exchanger 303; the output end of the sixth heat exchanger 303 is connected with the input end of the second expansion power generator 304; the output end of the second expansion power generator 304 is connected with the input end of the seventh heat exchanger 305; the output end of the seventh heat exchanger 305 is connected with the input end of the third expansion power generator 306; the output end of the third expansion power generator 306 is connected with the input end of the eighth heat exchanger 307; the output end of the eighth heat exchanger 307 is connected with the input end of the fourth expansion power generator 308; and the output end of the fourth expansion power generator 308 is connected with the second input end of the cold energy step storage unit 200 as the output end of the air expansion power generation unit 300.

[0036] A liquid air energy storage and power generation method based on a packed bed step storage, which is implemented based on the above-mentioned liquid air energy storage and power generation device based on a packed bed step storage, and includes the following steps:

[0037] The liquid air flows out of the liquid air storage tank 101, is pressurized by the low-temperature pump 102 to provide circulating power, and is pumped to the first heat exchanger 201, the second heat exchanger 202, the third heat exchanger 203 and the fourth heat exchanger 204 for stepwise vaporization; the vaporized air enters the air expansion power generation unit 300 for multi-stage heating and expansion power generation; the air after expansion with residual pressure enters the cold energy step storage unit 200 as a heat exchange fluid to heat the liquid air step by step and recover the vaporization cold energy to the first storage packed bed 205, the second storage packed bed 206, the third storage packed bed 207, the fourth storage packed bed 208, the fifth storage packed bed 209, the sixth storage packed bed 2010 and the seventh storage packed bed 2011 for stepwise storage; and finally, the air is discharged from the seventh storage packed bed 2011 into the environment.

[0038] The liquid air is subjected to stepwise heat exchange through the first heat exchanger 201, the second heat exchanger 202, the third heat exchanger 203 and the fourth heat exchanger 204, which can reduce the heat exchange temperature difference between the cold and hot ends of the heat exchanger and reduce the cold energy loss in the heat exchange process.

[0039] Specifically, the vaporization cold energy of liquid air is stored in multiple cold storage packed beds in stages, wherein the first cold storage packed bed 205 and the seventh cold storage packed bed 2011 store low-grade cold energy, the second cold storage packed bed 206 and the sixth cold storage packed bed 2010 store medium-grade cold energy, the third cold storage packed bed 207 and the fifth cold storage packed bed 209 store medium-high grade cold energy, and the fourth cold storage packed bed 208 stores high-grade cold energy. In this way, the vaporization cold energy is stored in multiple cold storage packed beds in stages, which can reduce the temperature gradient in each cold storage packed bed and reduce the cold-heat loss during storage. Embodiments

[0040] The liquid air flows out of the liquid air storage tank 101 and is pumped by the cryogenic pump 102 to the first heat exchanger 201, the first input end temperature of which is -175 DEG C, the second heat exchanger 202, the first input end temperature of which is -130 DEG C, the third heat exchanger 203, the first input end temperature of which is -90 DEG C, and the fourth heat exchanger 204, the first input end temperature of which is -50 DEG C, and the first output end temperature of which is -20 DEG C. In this way, the liquid air realizes staged heat exchange and cold energy recovery. The first cold storage packed bed 205 and the seventh cold storage packed bed 2011 store cold energy with a temperature gradient of -40 DEG C to -10 DEG C, the second cold storage packed bed 206 and the sixth cold storage packed bed 2010 store cold energy with a temperature gradient of -70 DEG C to -40 DEG C, the third cold storage packed bed 207 and the fifth cold storage packed bed 209 store cold energy with a temperature gradient of -110 DEG C to -70 DEG C, and the fourth cold storage packed bed 205 stores cold energy with a temperature gradient of -150 DEG C to -110 DEG C. In this way, the liquid air cold energy is stored in stages.

[0041] In summary, the present application reduces the heat exchange temperature difference, reduces the temperature gradient of the packed bed, and further reduces the cold-heat loss in the heat exchange and cold storage process, thereby improving the system efficiency, by means of staged heat exchange and staged cold storage. In addition, the present application uses the residual pressure after air power generation as the driving force, does not need an additional circulating fan, and can reduce the investment cost.

[0042] The description and practice disclosed in the present application are easy to think and understand for ordinary skilled persons in the technical field, and some improvements and refinements can be made without departing from the principles of the present application. Therefore, the modifications or improvements made without departing from the spirit of the present application should also be considered as the protection scope of the present application.

Claims

1. A liquid air energy storage power generation device based on packed bed cascade cold storage, characterized in that: The invention comprises a liquid air supply unit (100), a cold energy cascade storage and exchange unit (200), and an air expansion power generation unit (300); the liquid air supply unit (100) is connected to the cold energy cascade storage and exchange unit (200), and the cold energy cascade storage and exchange unit (200) is connected to the air expansion power generation unit (300); The liquid air in the liquid air supply unit (100) comes from the liquid air energy storage and charging process during the low electricity consumption period; the liquid air supply unit (100) is used to provide air medium and power for the liquid air power generation process, and the pressurized liquid air is transmitted to the cold energy cascade storage and exchange unit (200); The cold energy cascade storage and exchange unit (200) vaporizes the received liquid air in stages, stores the vaporized cold energy in stages, and transmits the vaporized air to the air expansion power generation unit (300); The air expansion power generation unit (300) heats the received gaseous air and sends it to the expansion generator for expansion and power generation, and transmits the discharged air with residual pressure as a heat exchange fluid to the cold energy cascade storage and exchange unit (200) to participate in the recovery and storage of liquid air cold energy; the air is finally discharged to the outside by the cold energy cascade storage and exchange unit (200); The liquid air supply unit (100) comprises a liquid air storage tank (101) and a cryogenic pump (102); the liquid air input of the liquid air storage tank (101) comes from the liquid air energy storage charging process during the low electricity consumption period; the output end of the liquid air storage tank (101) is connected to the input end of the cryogenic pump (102); the output end of the cryogenic pump (102) serves as the output end of the liquid air supply unit (100) and is connected to the first input end of the cold energy cascade storage and exchange unit (200); The cold energy cascade storage and exchange unit (200) comprises a first heat exchanger (201), a second heat exchanger (202), a third heat exchanger (203), a fourth heat exchanger (204), a first cold storage filled bed (205), a second cold storage filled bed (206), a third cold storage filled bed (207), a fourth cold storage filled bed (208), a fifth cold storage filled bed (209), a sixth cold storage filled bed (2010), and a seventh cold storage filled bed (2011); The first input end of the first heat exchanger (201) is connected to the output end of the liquid air supply unit (100) as the first input end of the cold energy cascade storage and exchange unit (200); the first output end of the first heat exchanger (201) is connected to the first input end of the second heat exchanger (202); the first output end of the second heat exchanger (202) is connected to the first input end of the third heat exchanger (203); the first output end of the third heat exchanger (203) is connected to the first input end of the fourth heat exchanger (204); the first output end of the fourth heat exchanger (204) is connected to the input end of the air expansion power generation unit (300) as the first output end of the cold energy cascade storage and exchange unit (200); The second input end of the fourth heat exchanger (204) is connected to the output end of the air expansion power generation unit (300) as the second input end of the cold energy cascade storage and exchange unit (200); the second output end of the fourth heat exchanger (204) is connected to the input end of the first cold storage filled bed (205); the output end of the first cold storage filled bed (205) is connected to the second input end of the third heat exchanger (203); the second output end of the third heat exchanger (203) is connected to the input end of the second cold storage filled bed (206); the output end of the second cold storage filled bed (206) is connected to the second input end of the second heat exchanger (202); the second output end of the second heat exchanger (202) is connected to the input end of the third cold storage filled bed (207) The output end of the third cold storage filled bed (207) is connected to the second input end of the first heat exchanger (201); the second output end of the first heat exchanger (201) is connected to the input end of the fourth cold storage filled bed (208); the output end of the fourth cold storage filled bed (208) is connected to the input end of the fifth cold storage filled bed (209); the output end of the fifth cold storage filled bed (209) is connected to the input end of the sixth cold storage filled bed (2010); the output end of the sixth cold storage filled bed (2010) is connected to the input end of the seventh cold storage filled bed (2011); the output end of the seventh cold storage filled bed (2011) is connected to the environment as the second output end of the cold energy cascade storage and exchange unit (200).

2. The liquid air energy storage power generation device based on packed bed cascade cold storage according to claim 1, characterized in that: The air expansion power generation unit (300) includes a fifth heat exchanger (301), a first expansion generator (302), a sixth heat exchanger (303), a second expansion generator (304), a seventh heat exchanger (305), a third expansion generator (306), an eighth heat exchanger (307) and a fourth expansion generator (308); The input end of the fifth heat exchanger (301) is connected to the first output end of the cold energy cascade storage and exchange unit (200) as the input end of the air expansion power generation unit (300); the output end of the fifth heat exchanger (301) is connected to the input end of the first expansion generator (302); the output end of the first expansion generator (302) is connected to the input end of the sixth heat exchanger (303); the output end of the sixth heat exchanger (303) is connected to the input end of the second expansion generator (304); the output end of the second expansion generator (304) is connected to the The seventh heat exchanger (305) is connected to the input end; the output end of the seventh heat exchanger (305) is connected to the input end of the third expansion generator (306); the output end of the third expansion generator (306) is connected to the input end of the eighth heat exchanger (307); the output end of the eighth heat exchanger (307) is connected to the input end of the fourth expansion generator (308); the output end of the fourth expansion generator (308) is connected to the second input end of the cold energy cascade storage and exchange unit (200) as the output end of the air expansion power generation unit (300).

3. A liquid air energy storage power generation method based on packed bed cascade cold storage, characterized in that: The method is implemented based on a liquid air energy storage power generation device based on packed bed cascade cold storage as described in any one of claims 1-2, comprising: Liquid air flows out of the liquid air storage tank (101), and is pressurized by a low-temperature pump (102) to provide circulation power. The liquid air is pumped to a first heat exchanger (201), a second heat exchanger (202), a third heat exchanger (203), and a fourth heat exchanger (204) for staged vaporization; the vaporized air enters an air expansion power generation unit (300) for multi-stage heating, expansion, and power generation; the expanded air with residual pressure enters a cold energy cascade storage and exchange unit (200) as a heat exchange fluid to stage-heat the liquid air and recover the vaporized cold energy to a first cold storage filled bed (205), a second cold storage filled bed (206), a third cold storage filled bed (207), a fourth cold storage filled bed (208), a fifth cold storage filled bed (209), a sixth cold storage filled bed (2010), and a seventh cold storage filled bed (2011) for staged storage; and finally, the air is discharged into the environment from the seventh cold storage filled bed (2011).

4. The liquid air energy storage and power generation method based on packed bed cascade cold storage according to claim 3 is characterized in that: The vaporization cold energy of the liquid air is stored in a plurality of cold storage packed beds in a stepwise manner, wherein the first cold storage packed bed (205) and the seventh cold storage packed bed (2011) store low-grade cold energy, the second cold storage packed bed (206) and the sixth cold storage packed bed (2010) store medium-grade cold energy, the third cold storage packed bed (207) and the fifth cold storage packed bed (209) store medium- and high-grade cold energy, and the fourth cold storage packed bed (208) stores high-grade cold energy.

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