A liquefied air energy storage system and working method

Abstract

The present invention discloses a liquefied air energy storage system, including an air liquefaction subsystem, a cold storage and heat regenerator, a liquid air storage tank, and a power generation subsystem. The cold storage and heat regenerator is provided with a heat exchange channel, and the liquid air storage tank is provided with a liquefied air inlet, a liquefied air outlet, and a cold air outlet. The air liquefaction subsystem, the heat exchange channel of the cold storage and heat regenerator, and the liquefied air inlet of the liquid air storage tank are sequentially connected through a liquefaction pipeline. A throttle valve is provided in front of the liquefied air inlet. The liquefied air outlet of the liquid air storage tank, the heat exchange channel of the cold storage and heat regenerator, and the power generation subsystem are sequentially connected through a gasification pipeline; a supercooling subsystem for cooling the air is provided on the liquefaction pipeline between the throttle valve and the heat exchange channel. The present invention also discloses a working method of a liquefied air energy storage system. The supercooling subsystem is added in the present invention to provide coldness for the liquefied air, so that it reaches a lower temperature and improves the liquefaction rate.

Description

Technical Field

[0001] The present invention relates to the field of energy storage, and in particular to a liquefied air energy storage system and a working method. Background Art

[0002] Liquid air energy storage technology is a new energy storage method that can achieve deep consumption and grid connection of new energy sources such as wind and solar, reasonably absorb off-peak electricity and various forms of waste heat resources of the power grid, and stably output various forms of energy such as cold, heat, electricity and industrial gas when needed. This technology has the outstanding advantages of large-scale long-term energy storage, clean and low-carbon, safe, long life and not restricted by geographical conditions.

[0003] Patent CN206073780U with publication number discloses a stratified cold storage device and a deep-cold liquefied air energy storage system using the stratified cold storage device. After the air passes through the stratified cold storage device, the temperature of the air is not low enough, so the liquefaction rate is low, and the mass ratio of liquid air to gaseous air is about 3:1. The air that cannot be liquefied cannot be converted and stored in the storage tank after being compressed and cooled. This part of the electrical energy converted into the internal energy of the low-temperature and high-pressure gaseous air cannot be stored, and the efficiency of converting electrical energy into the internal energy of liquefied air is reduced, resulting in less power generation from liquid air. Summary of the invention

[0004] The object of the present invention is to provide a liquefied air energy storage system.

[0005] The present invention also embodies a working method of a liquefied air energy storage system.

[0006] The innovation of the present invention is to add a supercooling subsystem to provide coldness for the liquefied air, so that it reaches a lower temperature and improves the liquefaction rate.

[0007] In order to achieve the above-mentioned object of the invention, the technical solution of the present invention is:

[0008] A liquefied air energy storage system comprises an air liquefaction subsystem, a cold storage and heat regenerator, a liquid air storage tank, and a power generation subsystem. The cold storage and heat regenerator is provided with a heat exchange channel, and the liquid air storage tank is provided with a liquefied air inlet, a liquefied air outlet, and a cold air outlet. The air liquefaction subsystem, the heat exchange channel of the cold storage and heat regenerator, and the liquefied air inlet of the liquid air storage tank are sequentially connected through a liquefaction pipeline. A throttle valve is provided in front of the liquefied air inlet. The liquefied air outlet of the liquid air storage tank, the heat exchange channel of the cold storage and heat regenerator, and the power generation subsystem are sequentially connected through a gasification pipeline. It is characterized in that a supercooling subsystem for cooling the air is provided on the liquefaction pipeline between the throttle valve and the heat exchange channel.

[0009] The air liquefaction subsystem compresses the air to obtain high-pressure air, which is then cooled to room temperature. The high-pressure air enters the heat exchange channel on the cold storage regenerator for cooling. The supercooling subsystem generates cold air to further reduce the temperature of the high-pressure air, thereby increasing the liquefaction rate of the air and improving the conversion efficiency of the entire system.

[0010] Furthermore, the subcooling subsystem includes a first compressor, a first cooler, a first heat exchanger, a second heat exchanger, and a first turbine expander connected through a circulation pipeline; a circulating working medium is arranged in the circulation pipeline, a first cooling channel and a first heating channel are arranged on the first heat exchanger, a second cooling channel, a second heating channel, and a subcooling channel are arranged on the second heat exchanger, and two ends of the subcooling channel are respectively connected to a throttle valve and a heat exchange channel; the circulating working medium flows through the first compressor, the first cooler, the first cooling channel, the second cooling channel, the first turbine expander, the second heating channel, and the first heating channel in sequence and then returns to the first compressor.

[0011] The circulating working fluid at normal temperature and pressure is pressurized by the first compressor, cooled by the first cooler, cooled by the first cooling channel and the second cooling channel, cooled by the first turbine expander, and then enters the second heating channel to exchange heat with the air in the supercooling channel for heating, and then passes through the first heating channel and the first cooling channel for heating, and then returns to the first compressor. The structure is simple and the overall efficiency is high.

[0012] Furthermore, the circulating working medium is a flowing medium with a boiling point below -190° C. Such flowing medium, such as air and nitrogen, has the characteristics of fast refrigeration speed and low cooling temperature.

[0013] Furthermore, a first air storage tank and a first filter are provided on the circulation pipeline, and the first air storage tank and the first filter are located between the first compressor and the first cooling channel. The first air storage tank buffers the pressure fluctuation of the supercooling subsystem, ensures the stable use of air in the supercooling subsystem, reduces the pulsation of air flow, and thus reduces the pressure fluctuation of the supercooling subsystem; the filter is used to remove impurities in the circulating medium to avoid blockage of the first heat exchanger and the second heat exchanger.

[0014] Furthermore, a first stop valve is provided on the circulation pipeline. The first stop valve is used to control the switch of the supercooling subsystem, and can be closed by the first stop valve when the supercooling subsystem does not need to be opened.

[0015] Furthermore, two second stop valves are provided on both the liquefaction pipeline and the gasification pipeline, and the second stop valves are located at both ends of the heat exchange channel. The liquefaction pipeline and the gasification pipeline cannot work at the same time, so when one pipeline is working, the second stop valve of the other pipeline needs to be closed, and the second stop valve is easy to control.

[0016] Furthermore, the air liquefaction subsystem includes a multi-stage second compressor connected in series, and a second cooler is provided at the rear end of each second compressor; the power generation subsystem includes a plurality of expansion generators connected in series and a heater for supplying heat to the expansion generators. The second compressor compresses the air and cools it to room temperature with the second cooler. After multi-stage compression, the air can reach the target pressure. The multi-stage compression has a small load on the second compressor, and the service life of the equipment is long. The multi-stage expansion generator expands and generates electricity, and the energy of air gasification and expansion is effectively utilized.

[0017] Furthermore, a second air storage tank and an air purification module are sequentially arranged on the liquefaction pipeline between the air liquefaction subsystem and the cold storage regenerator. The first air storage tank buffers the pressure fluctuation of the liquefied air energy storage system, ensures the smooth use of gas in the liquefied air energy storage system, reduces the pulsation of air flow, and thus reduces the pressure fluctuation of the liquefied air energy storage system; the air purification module ensures that the air remains clean when entering the cold storage regenerator and the liquid air storage tank.

[0018] Furthermore, the air purification module includes a cold dryer, a second filter, a degreaser, and a dryer which are connected in sequence by pipelines. The air is dusted, degreased, and dehydrated to prevent impurities and moisture from condensing in the pipeline, causing pipeline blockage or low heat exchange efficiency. The air remains clean and enters the cold storage regenerator.

[0019] A working method of a liquefied air energy storage system as claimed in claims 1 to 9, comprising the following steps:

[0020] S1 pressurizes and cools the air extracted from the atmosphere to form liquid air, and stores the liquid air in a liquid air storage tank;

[0021] S1.1 The air liquefaction subsystem extracts air from the atmosphere and compresses it to form high-pressure air. The pressure of the high-pressure air is 35~40Bar and the temperature is 30℃. The high-pressure air is sent to the cold storage regenerator;

[0022] S1.2 The high-pressure air cools down after passing through the heat exchange channel of the cold storage regenerator, and the heat of the high-pressure air is stored in the cold storage regenerator;

[0023] S1.3 After the high-pressure air comes out of the cold storage regenerator, its temperature drops to -140~-130℃, and it is cooled again by the subcooling subsystem, and its temperature drops to -160~-150℃. Then the high-pressure air passes through the throttle valve and liquefies to form mixed air. The mass ratio of liquid air to gaseous air in the mixed air is 9~15:1, the temperature of the mixed air is -170~-165℃, and the pressure is 20~25Bar. The mixed air enters the liquid air storage tank from the liquefied air inlet, and the liquid air in the mixed air is stored in the liquid air storage tank, and the gaseous air in the mixed air is discharged from the cold air outlet;

[0024] S2 heats up and gasifies the liquid air in the liquid air storage tank to form room temperature air, and the room temperature air enters the power generation subsystem to expand and generate electricity;

[0025] S2.1 The liquid air in the liquid air storage tank is transported to the cold storage regenerator;

[0026] S2.2 When the liquid air passes through the heat exchange channel of the cold storage regenerator, it absorbs the heat stored in the cold storage regenerator in step S1.2, and the liquid air vaporizes to form a normal temperature gas, and the coldness of the liquid air is retained in the cold storage regenerator;

[0027] S2.2 The room temperature gas comes out of the cold storage regenerator and enters the power generation subsystem. After the room temperature gas is heated up, it expands to generate electricity and is finally discharged into the atmosphere at room temperature.

[0028] The secondary cooling is carried out through the supercooling subsystem, and the mass ratio of liquefied liquid air and gaseous air after throttling is increased to 9~15:1, and the conversion rate of electrical energy into the internal energy of liquid air is high.

[0029] The beneficial effects of the present invention are:

[0030] 1. The present invention adds a subcooling subsystem to provide cooling capacity for the liquefied air, so that it reaches a lower temperature and improves the liquefaction rate.

[0031] 2. In the present invention, the first air storage tank serves to buffer the pressure fluctuation of the supercooling subsystem, ensure the smooth use of air in the supercooling subsystem, reduce the pulsation of air flow, and thus reduce the pressure fluctuation of the supercooling subsystem; the filter is used to remove impurities in the circulating medium to avoid blockage of the first heat exchanger and the second heat exchanger.

[0032] 3. In the present invention, the first air storage tank buffers the pressure fluctuation of the liquefied air energy storage system, ensures the smooth use of gas in the liquefied air energy storage system, reduces the pulsation of air flow, and thus reduces the pressure fluctuation of the liquefied air energy storage system; the air purification module ensures that the air remains clean when entering the cold storage regenerator and the liquid air storage tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 It is a structural schematic diagram of the present invention. Implementation

[0034] The technical solutions in the embodiments of the present invention will be described clearly and completely below in conjunction with the accompanying drawings.

[0035] Example 1: Figure 1As shown, a liquefied air energy storage system includes an air liquefaction subsystem 1, a cold storage regenerator 2, a liquid air storage tank 3, and a power generation subsystem 4. The air liquefaction subsystem 1 includes a multi-stage series-connected second compressor 1.1, and a second cooler 1.2 is provided at the rear end of each second compressor 1.1; the power generation subsystem 4 includes a plurality of series-connected expansion generators 4.1 and a heater 4.2 for supplying heat to the expansion generators 4.1; the cold storage regenerator 2 is provided with a heat exchange channel 2.1, and the liquid air storage tank 3 is provided with a liquefied air inlet 3.1, a liquefied air outlet 3.2, and a cold air outlet 3.3. The liquefied air inlet 3.1 is connected in sequence through the liquefaction pipeline 7. A throttle valve 8 is provided in front of the liquefied air inlet 3.1. The liquefied air outlet 3.2 of the liquefied air storage tank, the heat exchange channel 2.1 of the cold storage regenerator, and the power generation subsystem 4 are connected in sequence through the gasification pipeline 9. Two second stop valves 10 are provided on the liquefaction pipeline 7 and the gasification pipeline 9. The second stop valves 10 are located at both ends of the heat exchange channel 2.1. The second air storage tank 5 and the air purification module 6 are provided in sequence on the liquefaction pipeline 7 between the air liquefaction subsystem 1 and the cold storage regenerator 2. The air purification module 6 includes a cold dryer 6.1, a second filter 6.2, a degreaser 6.3, and a dryer 6.4 which are connected in sequence through pipelines; the throttle valve 8 and A subcooling subsystem 11 for cooling the air is provided on the liquefaction pipeline 7 between the heat exchange channels 2.1. The subcooling subsystem 11 comprises a first compressor 11.2, a first cooler 11.3, a first heat exchanger 11.4, a second heat exchanger 11.5 and a first turbo expander 11.6 which are connected through a circulation pipeline 11.1. A circulating medium is provided in the circulation pipeline 11.1. The circulating medium is a flowing medium with a boiling point below -190°C. A first cooling channel 11.41 and a first heating channel 11.42 are provided on the first heat exchanger 11.4. A second cooling channel 11.51, a second heating channel 11.52 and a subcooling channel 11.53 are provided on the second heat exchanger 11.5. The two ends of the supercooling channel 11.53 are connected to the throttle valve 8 and the heat exchange channel 2.1 respectively; the circulating medium flows through the first compressor 11.2, the first cooler 11.3, the first cooling channel 11.41, the second cooling channel 11.42, the first turbo expander 11.5, the second heating channel 11.51, the first heating channel 11.42 in sequence and then returns to the first compressor 11.2; a first air storage tank 11.7 and a first filter 11.8 are provided on the circulation pipeline 11.1, and the first air storage tank 11.7 and the first filter 11.8 are located between the first compressor 11.2 and the first cooling channel 11.41; a first stop valve 11.9 is provided on the circulation pipeline 11.1.

[0036] Embodiment 2: A working method of a liquefied air energy storage system. When liquefied air stores energy, the air liquefaction subsystem extracts air from the atmosphere and compresses it to form high-pressure air. The pressure of the high-pressure air is 35 Bar and the temperature is 30°C. The high-pressure air is sent to the cold storage regenerator; the high-pressure air is cooled after passing through the heat exchange channel of the cold storage regenerator, and the heat of the high-pressure air is stored in the cold storage regenerator; the temperature of the high-pressure air drops to -135°C after coming out of the cold storage regenerator, and is cooled again by the supercooling subsystem to -155°C. Then the high-pressure air passes through the throttle valve and liquefies to form mixed air. The mass ratio of liquid air to gaseous air in the mixed air is 12.5:1. The temperature of the mixed air is -170°C and the pressure is 20 Bar. The mixed air enters the liquid air storage tank from the liquefied air inlet, and the liquid air in the mixed air is stored in the liquid air storage tank. The gaseous air in the mixed air is discharged from the cold air outlet;

[0037] When the liquid air vaporizes to release energy, the liquid air in the liquid air storage tank is transported to the cold storage regenerator; when the liquid air passes through the heat exchange channel of the cold storage regenerator, it absorbs the heat stored in the cold storage regenerator in step S1.2, and the liquid air vaporizes to form room temperature gas, and the cold energy of the liquid air remains in the cold storage regenerator; after the room temperature gas comes out of the cold storage regenerator, it enters the power generation subsystem, and after the room temperature gas is heated up, it expands to generate electricity, and finally is discharged into the atmosphere at room temperature.

[0038] Embodiment 3: A working method of a liquefied air energy storage system. When liquefied air stores energy, the air liquefaction subsystem extracts air from the atmosphere and compresses it to form high-pressure air. The pressure of the high-pressure air is 38 Bar and the temperature is 30°C. The high-pressure air is sent to the cold storage regenerator; the high-pressure air is cooled after passing through the heat exchange channel of the cold storage regenerator, and the heat of the high-pressure air is stored in the cold storage regenerator; the temperature of the high-pressure air drops to -130°C after coming out of the cold storage regenerator, and is cooled again by the supercooling subsystem to -150°C, and then the high-pressure air is liquefied to form mixed air after passing through the throttle valve. The mass ratio of liquid air to gaseous air in the mixed air is 9:1, the temperature of the mixed air is -165°C and the pressure is 25 Bar, the mixed air enters the liquid air storage tank from the liquefied air inlet, the liquid air in the mixed air is stored in the liquid air storage tank, and the gaseous air in the mixed air is discharged from the cold air outlet;

[0039] When the liquid air vaporizes to release energy, the liquid air in the liquid air storage tank is transported to the cold storage regenerator; when the liquid air passes through the heat exchange channel of the cold storage regenerator, it absorbs the heat stored in the cold storage regenerator in step S1.2, and the liquid air vaporizes to form room temperature gas, and the cold energy of the liquid air remains in the cold storage regenerator; after the room temperature gas comes out of the cold storage regenerator, it enters the power generation subsystem, and after the room temperature gas is heated up, it expands to generate electricity, and finally is discharged into the atmosphere at room temperature.

[0040] Embodiment 4: A working method of a liquefied air energy storage system. When liquefied air stores energy, the air liquefaction subsystem extracts air from the atmosphere and compresses it to form high-pressure air. The pressure of the high-pressure air is 40 Bar and the temperature is 30°C. The high-pressure air is sent to the cold storage regenerator; the high-pressure air is cooled after passing through the heat exchange channel of the cold storage regenerator, and the heat of the high-pressure air is stored in the cold storage regenerator; the temperature of the high-pressure air drops to -140°C after coming out of the cold storage regenerator, and is cooled again by the supercooling subsystem to -160°C, and then the high-pressure air is liquefied to form mixed air after passing through the throttle valve. The mass ratio of liquid air to gaseous air in the mixed air is 15:1, the temperature of the mixed air is -172°C and the pressure is 22 Bar, the mixed air enters the liquid air storage tank from the liquefied air inlet, the liquid air in the mixed air is stored in the liquid air storage tank, and the gaseous air in the mixed air is discharged from the cold air outlet;

[0041] When the liquid air vaporizes to release energy, the liquid air in the liquid air storage tank is transported to the cold storage regenerator; when the liquid air passes through the heat exchange channel of the cold storage regenerator, it absorbs the heat stored in the cold storage regenerator in step S1.2, and the liquid air vaporizes to form room temperature gas, and the cold energy of the liquid air remains in the cold storage regenerator; after the room temperature gas comes out of the cold storage regenerator, it enters the power generation subsystem, and after the room temperature gas is heated up, it expands to generate electricity, and finally is discharged into the atmosphere at room temperature.

[0042] The described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

Claims

1. A working method of a liquefied air energy storage system, the liquefied air energy storage system comprising an air liquefaction subsystem, a cold storage regenerator, a liquid air storage tank, and a power generation subsystem, the cold storage regenerator is provided with a heat exchange channel, the liquid air storage tank is provided with a liquefied air inlet, a liquefied air outlet, and a cold air outlet, the air liquefaction subsystem, the heat exchange channel of the cold storage regenerator, and the liquefied air inlet of the liquid air storage tank are sequentially connected through a liquefaction pipeline, a throttle valve is provided in front of the liquefied air inlet, the liquefied air outlet of the liquid air storage tank, the heat exchange channel of the cold storage regenerator, and the power generation subsystem are sequentially connected through a gasification pipeline; a supercooling subsystem for cooling the air is provided on the liquefaction pipeline between the throttle valve and the heat exchange channel; it is characterized in that The following steps are involved: S1 pressurizes and cools the air extracted from the atmosphere to form liquid air, and stores the liquid air in a liquid air storage tank; S1.1 The air liquefaction subsystem extracts air from the atmosphere and compresses it to form high-pressure air. The pressure of the high-pressure air is 35~40Bar and the temperature is 30℃. The high-pressure air is sent to the cold storage regenerator; S1.2 The high-pressure air cools down after passing through the heat exchange channel of the cold storage regenerator, and the heat of the high-pressure air is stored in the cold storage regenerator; S1.3 After the high-pressure air comes out of the cold storage regenerator, its temperature drops to -140~-130℃, and it is cooled again by the subcooling subsystem, and its temperature drops to -160~-150℃. Then the high-pressure air passes through the throttle valve and liquefies to form mixed air. The mass ratio of liquid air to gaseous air in the mixed air is 9~15:1, the temperature of the mixed air is -170~-165℃, and the pressure is 20~25Bar. The mixed air enters the liquid air storage tank from the liquefied air inlet, and the liquid air in the mixed air is stored in the liquid air storage tank, and the gaseous air in the mixed air is discharged from the cold air outlet; S2 heats up and gasifies the liquid air in the liquid air storage tank to form room temperature air, and the room temperature air enters the power generation subsystem to expand and generate electricity; S2.1 The liquid air in the liquid air storage tank is transported to the cold storage regenerator; S2.2 When the liquid air passes through the heat exchange channel of the cold storage regenerator, it absorbs the heat stored in the cold storage regenerator in step S1.2, and the liquid air vaporizes to form a normal temperature gas, and the coldness of the liquid air is retained in the cold storage regenerator; S2.3 The room temperature gas comes out of the cold storage heat regenerator and enters the power generation subsystem. The room temperature gas expands to generate electricity after heating up, and finally is discharged into the atmosphere at room temperature.

2. The working method of the liquefied air energy storage system according to claim 1, characterized in that: The subcooling subsystem includes a first compressor, a first cooler, a first heat exchanger, a second heat exchanger, and a first turbine expander connected through a circulation pipeline; a circulating working medium is arranged in the circulation pipeline, a first cooling channel and a first heating channel are arranged on the first heat exchanger, a second cooling channel, a second heating channel, and a subcooling channel are arranged on the second heat exchanger, and two ends of the subcooling channel are connected to a throttle valve and a heat exchange channel respectively; the circulating working medium flows through the first compressor, the first cooler, the first cooling channel, the second cooling channel, the first turbine expander, the second heating channel, and the first heating channel in sequence and then returns to the first compressor.

3. The working method of the liquefied air energy storage system according to claim 2, characterized in that: The circulating working fluid is a flowing medium with a boiling point below -190°C.

4. The working method of the liquefied air energy storage system according to claim 2, characterized in that: The circulation pipeline is provided with a first air storage tank and a first filter, and the first air storage tank and the first filter are located between the first compressor and the first cooling channel.

5. The working method of the liquefied air energy storage system according to claim 2, characterized in that: A first stop valve is arranged on the circulation pipeline.

6. The working method of the liquefied air energy storage system according to claim 1, characterized in that: Two second stop valves are arranged on the liquefaction pipeline and the gasification pipeline, and the second stop valves are located at both ends of the heat exchange channel.

7. The working method of the liquefied air energy storage system according to claim 1, characterized in that: The air liquefaction subsystem comprises a plurality of second compressors connected in series, and a second cooler is arranged at the rear end of each second compressor; the power generation subsystem comprises a plurality of expansion generators connected in series and a heater for supplying heat to the expansion generators.

8. The working method of the liquefied air energy storage system according to claim 1, characterized in that: A second air storage tank and an air purification module are sequentially arranged on the liquefaction pipeline between the air liquefaction subsystem and the cold storage heat regenerator.

9. The working method of the liquefied air energy storage system according to claim 8, characterized in that: The air purification module comprises a cold dryer, a second filter, a degreaser and a dryer which are sequentially connected by pipelines.

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