Liquefied air energy storage system

Abstract

The utility model discloses a liquefied air energy storage system which comprises a molecular sieve water separator and a molecular sieve adsorption tower, a separator air output pipe is connected with a top gas connecting pipe of the molecular sieve adsorption tower, and a bottom gas connecting pipe of the molecular sieve adsorption tower is connected with a cold box front compressor unit. The cold box front compressor unit is communicated with an air pipeline in the cold box, and an outlet of the air pipeline in the cold box is communicated with a first liquefied air storage tank through a first liquefied air output pipe with a first throttling valve; the output end of a liquid air pressure pump on a first liquefied air storage tank output pipe of the first liquefied air storage tank is communicated with the air input end of the expansion unit, the air output end of the expansion unit is provided with a hot blowing conveying pipe and a cold blowing conveying pipe, and the hot blowing conveying pipe is communicated with a bottom gas connecting pipe through a first heater and an electric heater; and the output end of the cold blowing gas conveying pipe is connected to the output end of the electric heater output pipe. The device has the advantages of simple structure, low energy consumption and full utilization of heat energy.

Description

Technical Field

[0001] This utility model relates to the field of energy storage technology, specifically to a liquefied air energy storage system. Background Technology

[0002] Liquefied air storage technology typically refers to the use of electricity to compress air and then cryogenically liquefy it in storage tanks during periods of low electricity prices; during periods of high electricity prices, the liquefied air is pressurized and expanded to drive a gas turbine and generator to generate electricity.

[0003] Current liquefied air energy storage systems have some drawbacks: the two-tower and three-tower molecular sieve dehydration and decarbonization processes require additional energy consumption to pressurize the regenerated gas, which leads to high costs and poor process continuity of liquefied air energy storage technology. Utility Model Content

[0004] The technical problem to be solved by this utility model is to provide a liquefied air energy storage system, which only sets a single molecular sieve adsorption tower, has a simple structure, low cost, low energy consumption, can store energy during the off-peak period of electricity price at night and release energy during the peak period of electricity price during the day, and has high energy storage density and large energy storage capacity.

[0005] To solve the above problems, the technical solution adopted by this utility model is: a liquefied air energy storage system, comprising: a molecular sieve water separator for removing free water from the air and a molecular sieve adsorption tower for removing carbon dioxide and moisture from the air. The molecular sieve water separator is connected to a separator air inlet pipe, a separator air outlet pipe and a separator drain pipe. The separator air inlet pipe is connected to a compressor unit. The separator air outlet pipe is connected to the top gas pipe of the molecular sieve adsorption tower. The bottom gas pipe of the molecular sieve adsorption tower is connected to the air inlet of the cold box pre-compressor unit. A bottom gas pipe control valve is provided on the bottom gas pipe. The air outlet of the cold box pre-compressor unit is connected to the inlet of the air pipeline in the cold box. The outlet of the air pipeline in the cold box is connected to a first liquefied air outlet pipe with a first throttling valve. The first liquefied air outlet pipe is connected to a first liquefied air storage tank.

[0006] A liquid air pressurization pump is installed on the output pipe of the first liquefied air storage tank. The output end of the liquid air pressurization pump is connected to the air input end of the expander unit. The air output end of the expander unit is equipped with a hot air delivery pipe with a hot air output control valve, a cold air delivery pipe with a cold air output control valve, and an expander discharge pipe. The hot air delivery pipe is connected to the inlet of the first heater of the first heater, and the outlet of the first heater is connected to the inlet of the electric heater. The outlet of the electric heater is equipped with an electric heater output pipe, which is connected to the bottom gas connection between the molecular sieve adsorption tower and the bottom gas connection control valve. The output end of the electric heater output pipe is equipped with a first check valve and a first backflush control valve. The output end of the cold air delivery pipe is connected to the output end of the electric heater output pipe, and the output end of the cold air delivery pipe is equipped with a second check valve. The top gas connection of the molecular sieve adsorption tower is connected to a molecular sieve adsorption tower regeneration gas output pipe, and the molecular sieve adsorption tower regeneration gas output control valve is installed on the molecular sieve adsorption tower regeneration gas output pipe.

[0007] Furthermore, in the aforementioned liquefied air energy storage system, a second air pipeline is also provided inside the cold box. The air output end of the cold box pre-compressor unit is connected to the inlet of the second air pipeline inside the cold box. The outlet of the second air pipeline is connected to a second liquefied air output pipe with a second throttle valve, and the second liquefied air output pipe is connected to a second liquefied air storage tank. A cooling medium liquid air pipeline is provided inside the cold box. The outlet pipe of the second liquefied air storage tank on the second liquefied air storage tank is connected to the inlet of the cooling medium liquid air pipeline inside the cold box. A low-temperature air pipeline is also provided inside the cold box. The low-temperature air output pipe of the second liquefied air storage tank on the top of the second liquefied air storage tank is connected to the inlet of the low-temperature air pipeline inside the cold box. The outlet of the cooling medium liquid air pipeline and the outlet of the low-temperature air pipeline are both connected to the air input end of the cold box pre-compressor unit.

[0008] Furthermore, in the aforementioned liquefied air energy storage system, an LNG pipeline is installed inside the cold box, with the inlet of the LNG pipeline connected to a liquefied natural gas input pipe and the outlet of the LNG pipeline connected to a liquefied natural gas output pipe.

[0009] Furthermore, in the aforementioned liquefied air energy storage system, a low-temperature nitrogen pipeline is installed inside the cold box. The inlet of the low-temperature nitrogen pipeline is connected to a nitrogen input pipe, which is connected to a nitrogen storage bed. The outlet of the low-temperature nitrogen pipeline is connected to a first nitrogen return pipe, which is connected to the nitrogen storage bed. A first nitrogen delivery pump is installed on the first nitrogen return pipe.

[0010] Furthermore, in the aforementioned liquefied air energy storage system, a liquid air-nitrogen heat exchanger and a regenerator are also provided between the output end of the liquid air booster pump and the air input end of the expander unit. The output end of the liquid air booster pump is connected to the liquid air input end of the liquid air-nitrogen heat exchanger, the liquid air output end of the liquid air-nitrogen heat exchanger is connected to the inlet of the regenerator cooling medium pipeline in the regenerator through a pipeline, and the outlet of the regenerator cooling medium pipeline in the regenerator is connected to the air input end of the expander unit.

[0011] A nitrogen output pipe is installed on the nitrogen storage bed. The nitrogen output pipe is connected to the inlet of the nitrogen medium heat exchange tube in the liquid air nitrogen heat exchanger. A second nitrogen delivery pump is installed on the nitrogen output pipe. A second nitrogen return pipe is installed at the outlet of the nitrogen medium heat exchange tube in the liquid air nitrogen heat exchanger. The second nitrogen return pipe is connected to the nitrogen storage bed.

[0012] The regenerated gas output end of the regenerated gas cooler is connected to the regenerated gas moisture separator. The bottom of the regenerated gas moisture separator is provided with a regenerated gas moisture separator drain pipe, and the regenerated gas moisture separator is provided with a regenerated gas moisture separator gas discharge pipe. The regenerated gas output pipe of the molecular sieve adsorption tower is connected to the regenerated gas input end of the regenerated gas cooler.

[0013] Furthermore, in the aforementioned liquefied air energy storage system, the compressor unit connected to the separator air input pipe is a two-stage compressor unit. The two-stage compressor unit includes a first compressor and a first compression cooler, a second compressor and a second compression cooler connected in series. The air input end of the first compressor is connected to an air source, and the air output end of the second cooler is connected to the separator air input pipe on the molecular sieve moisture separator. The cold box pre-compressor unit includes a cold box pre-compressor and a cold box pre-compressor cooler connected in series.

[0014] Furthermore, the aforementioned liquefied air energy storage system further includes a water circulation system, which comprises: a cooling water storage tank, which is connected to the cooling medium inlets of a first compressor cooler, a second compressor cooler, and a pre-compressor cooler of the cold box via a first cooling water outlet pipe, a second cooling water outlet pipe, and a third cooling water outlet pipe, respectively; the cooling medium outlets of the first compressor cooler, the second compressor cooler, and the pre-compressor cooler of the cold box are all connected to a high-temperature water storage tank via pipelines; the high-temperature water storage tank is connected to the first heater heating medium inlet of a first heater via a first high-temperature water storage tank outlet pipe; the first heater heating medium outlet of the first heater is connected to a first heater water outlet pipe; and the first heater water outlet pipe is connected to a medium-temperature water storage tank.

[0015] The expander assembly includes a primary expansion preheater, a primary expander, a secondary expansion preheater, a secondary expander, a tertiary expansion preheater, and a tertiary expander connected in series. A second high-temperature water storage tank outlet pipe is installed on the high-temperature water storage tank. This outlet pipe is connected to the preheating medium inlets of the primary, secondary, and tertiary expansion preheaters via primary, secondary, and tertiary preheating water pipes, respectively. The preheating medium outlets of the primary, secondary, and tertiary expansion preheaters are connected to a medium-temperature water storage tank via water pipes. The medium-temperature water storage tank is connected to a low-temperature water storage tank via a water cooler.

[0016] Furthermore, in the aforementioned liquefied air energy storage system, the electric heater is equipped with a frequency converter, and the outlet of the heated medium of the first heater is equipped with an air temperature sensor, which is interlocked with the temperature signal of the frequency converter.

[0017] The advantages of this invention are: 1. By setting up a single molecular sieve adsorption tower and using air from the air output of the expander unit for backflushing to regenerate the molecular sieve adsorption tower, the overall equipment cost is effectively reduced. 2. By using high-temperature water generated by the compressor unit as a heating medium to heat the air used for regeneration of the molecular sieve adsorption tower, thermal energy is fully utilized, effectively saving energy consumption and thus reducing the operating cost of the entire liquefied air energy storage system. 3. The installation and signal interlocking of the electric heater with frequency converter and the air temperature sensor ensure that the temperature of the air used for regeneration of the molecular sieve adsorption tower is within the set value, thereby ensuring the efficiency of the molecular sieve adsorption tower regeneration. 4. The entire liquefied air energy storage system has a simple structure, low energy consumption, and can store energy during off-peak electricity prices at night and release energy during peak electricity prices during the day, resulting in high energy density and large energy storage capacity. Attached Figure Description

[0018] Figure 1 This is a schematic diagram of the principle structure of a liquefied air energy storage system according to the present invention.

[0019] Figure 2 yes Figure 1 Enlarged structural diagram of side A of axis OO.

[0020] Figure 3 yes Figure 1 Enlarged structural diagram of side B of axis OO. Detailed Implementation

[0021] The present invention will now be described in further detail with reference to the accompanying drawings and preferred embodiments.

[0022] like Figure 1 , Figure 2 , Figure 3As shown, a liquefied air energy storage system includes: a molecular sieve water separator 1 for removing free water from the air and a molecular sieve adsorption tower 2 for removing carbon dioxide and moisture from the air. The molecular sieve water separator 1 is connected to a separator air inlet pipe 11, a separator air outlet pipe 12, and a separator drain pipe 13. The separator air inlet pipe 11 is connected to a two-stage compressor unit. The two-stage compressor unit includes a first compressor 401 and a first compressor cooler 402, a second compressor 403, and a second compressor cooler 404 connected in series. The air inlet of the first compressor 401 is connected to an air source, typically filtered clean air. The air outlet of the second compressor cooler 404 is connected to the separator air inlet pipe 11.

[0023] The separator air output pipe 12 is connected to the top gas inlet pipe 21 of the molecular sieve adsorption tower 2. The bottom gas inlet pipe 22 of the molecular sieve adsorption tower 2 is connected to the air inlet of the cold box pre-compressor unit. The cold box pre-compressor unit includes a cold box pre-compressor 405 and a cold box pre-compressor cooler 406 connected in series. A bottom gas inlet pipe control valve 221 is provided on the bottom gas inlet pipe 22.

[0024] The exhaust end of the pre-compressor unit in the cold box is connected to the inlet of the first air pipe 31 inside the cold box 3. The outlet of the first air pipe 31 inside the cold box 3 is connected to a first liquefied air output pipe 34 with a first throttle valve 341. The first liquefied air output pipe 34 is connected to the first liquefied air storage tank 4.

[0025] The first liquefied air storage tank 4's outlet pipe 41 is connected to the liquid air pressurization pump 411, and the output end of the liquid air pressurization pump 411 is connected to the air input end of the expander unit. The expander unit includes a primary expansion preheater 51, a primary expander 52, a secondary expansion preheater 53, a secondary expander 54, a tertiary expansion preheater 55, and a tertiary expander 56 connected in series. The air input end of the expander unit is the air input end 511 of the primary expansion preheater 51. The air output end of the expander unit is the air output end 561 of the tertiary expander 56.

[0026] The air outlet 561 of the three-stage expander 56 is equipped with a hot air delivery pipe 57 with a hot air delivery control valve 571, a cold air delivery pipe 58 with a cold air delivery control valve 581, and an expander discharge pipe 59. When the system needs to use hot air, the hot air delivery control valve 571 opens. When cold air is needed, the cold air delivery control valve 581 opens. When gas needs to be discharged, air from the air outlet 561 of the three-stage expander 56 is discharged from the expander discharge pipe 59.

[0027] The hot air delivery pipe 27 is connected to the inlet 61 of the first heater 6, and the outlet 62 of the first heater 6 is connected to the inlet of the electric heater 7. The outlet of the electric heater 7 is provided with an electric heater output pipe 71. The output end of the electric heater output pipe 71 is equipped with a backflush control valve 711 and a first check valve 712. The electric heater output pipe 71 is connected to the bottom gas connection pipe 22 between the molecular sieve adsorption tower 2 and the bottom gas connection pipe control valve 221. The output end of the cold air delivery pipe 58 is connected to the output end of the electric heater output pipe 71, and the output end of the cold air delivery pipe 58 is equipped with a second check valve 582. The top gas connection pipe 21 of the molecular sieve adsorption tower 2 is connected to a molecular sieve adsorption tower regeneration gas output pipe 23, and the molecular sieve adsorption tower regeneration gas output control valve 231 is provided on the molecular sieve adsorption tower regeneration gas output pipe 23. When the molecular sieve adsorption tower 2 is regenerated, the molecular sieve adsorption tower regeneration gas output control valve 231 and the backflush control valve 711 are opened, and the bottom gas connection pipe control valve 221 is closed.

[0028] In this embodiment, to save energy and fully utilize the cooling capacity of liquid air, a second air pipeline 32 is also provided inside the cold box 3. The air output end of the cold box pre-compressor unit is also connected to the inlet of the second air pipeline 32 inside the cold box 3. The outlet of the second air pipeline 32 is connected to a second liquefied air output pipe 35 with a second throttle valve 351. The second liquefied air output pipe 35 is connected to the second liquefied air storage tank 8. A cooling medium liquid air pipeline 36 is provided inside the cold box 3. The second liquefied air storage tank output pipe 81 on the second liquefied air storage tank 8 is connected to the inlet of the cooling medium liquid air pipeline 36 inside the cold box 3. A low-temperature air pipeline 33 is provided inside the cold box 3. The second liquefied air storage tank low-temperature air output pipe 82 on the top of the second liquefied air storage tank 8 is connected to the inlet of the low-temperature air pipeline 33 inside the cold box 3. The outlet of the cooling medium liquid air pipeline 36 and the outlet of the low-temperature air pipeline 33 are both connected to the air input end of the cold box pre-compressor unit, that is, the air input end of the cold box pre-compressor 405.

[0029] The cold box 3 is also equipped with other refrigerant pipelines. The refrigerant is not limited to any particular type, as long as it can provide sufficient cooling for air liquefaction. In this embodiment, liquefied natural gas (LNG) is used as the cooling medium. The cooling medium pipeline is an LNG pipeline 37, with an LNG input pipe 371 connected to the inlet of the LNG pipeline 37 and an LNG output pipe 372 connected to the outlet of the LNG pipeline 37.

[0030] The cold box 3 is also equipped with a low-temperature nitrogen pipeline 38, and the low-temperature nitrogen in the low-temperature nitrogen pipeline 38 is also used as the refrigerant of the cold box. The inlet of the low-temperature nitrogen pipeline 38 is connected to a nitrogen input pipe 381, which is connected to the nitrogen storage bed 9. The outlet of the nitrogen input pipe 381 is connected to a first nitrogen return pipe 382, ​​which is connected to the nitrogen storage bed 9. A first nitrogen transfer pump 383 is installed on the first nitrogen return pipe 382.

[0031] In this embodiment, a liquid-air-nitrogen heat exchanger 10 and a regenerated gas cooler 20 are also installed between the output end of the liquid-air pressurization pump 411 and the air input end of the expander unit, that is, between the output end of the liquid-air pressurization pump 411 and the air input end 101 of the liquid-air-nitrogen heat exchanger 10. The liquid-air output end 102 of the liquid-air-nitrogen heat exchanger 10 is connected to the inlet 201 of the regenerated gas cooling medium pipeline in the regenerated gas cooler 20 via a pipeline. The outlet 202 of the regenerated gas cooling medium pipeline in the regenerated gas cooler 20 is connected to the air input end of the expander unit, that is, to the air input end 511 of the first-stage expander preheater 51. The low-temperature air output from the liquid-air pressurization pump 411 is used as the refrigerant in the liquid-air-nitrogen heat exchanger 10 and the regenerated gas cooler 20 in sequence.

[0032] A nitrogen outlet pipe 91 is installed on the nitrogen storage bed 9, which is connected to the inlet 103 of the nitrogen medium heat exchange tube in the liquid-air nitrogen heat exchanger 10. A second nitrogen transfer pump 911 is installed on the nitrogen outlet pipe 91. A second nitrogen return pipe 92 is installed at the outlet 104 of the nitrogen medium heat exchange tube in the liquid-air nitrogen heat exchanger 9, which is connected to the liquid nitrogen storage tank 9. After exchanging heat with the low-temperature air in the liquid-air nitrogen heat exchanger 10 to obtain cooling capacity, the nitrogen returns to the nitrogen storage bed 9.

[0033] The regenerated gas output end 204 of the regenerated gas cooler 20 is connected to the regenerated gas moisture separator 30. The bottom of the regenerated gas moisture separator 30 is provided with a regenerated gas moisture separator drain pipe 301, and the regenerated gas moisture separator 30 is provided with a regenerated gas moisture separator gas discharge pipe 302. The molecular sieve adsorption tower regenerated gas output pipe 23 is connected to the regenerated gas input end 203 of the regenerated gas cooler 20.

[0034] This embodiment also includes a water circulation system, which comprises a cooling water storage tank 50. The cooling water storage tank 50 is connected to the cooling medium inlets of the first compression cooler 402, the second compression cooler 404, and the cold box pre-compression cooler 406 via a first cooling water outlet pipe 501, a second cooling water outlet pipe 502, and a third cooling water outlet pipe 503, respectively. The cooling medium outlets of the first compression cooler 402, the second compression cooler 404, and the cold box pre-compression cooler 406 are all connected to a high-temperature water storage tank 60 via pipelines. The cold water in the cooling water storage tank 50 is used as the cooling medium in the first compression cooler 402, the second compression cooler 404, and the cold box pre-compression cooler 406. The high-temperature water storage tank 60 is connected to the first heater heating medium inlet 63 of the first heater 6 via a first high-temperature water storage tank outlet pipe 601. The first heater heating medium outlet 64 of the first heater 6 is connected to a first heater water outlet pipe 65, which is connected to a medium-temperature water storage tank 70. The electric heater 7 is equipped with a frequency converter 72, and an air temperature sensor 621 is installed on the pipeline of the outlet 62 of the first heater of the first heater 6. The air temperature sensor 621 is interlocked with the temperature signal of the frequency converter 71.

[0035] A second high-temperature water storage tank outlet pipe 602 is installed on the high-temperature water storage tank 60. The second high-temperature water storage tank outlet pipe 602 is connected to the preheating medium inlets of the first-stage preheating water pipe 6021, the second-stage preheating water pipe 6022, and the third-stage preheating water pipe 6023, respectively. The preheating medium outlets of the first-stage preheating water pipe 51, the second-stage preheating water pipe 53, and the third-stage preheating water pipe 55 are connected to the medium-temperature water storage tank 70 through water pipes. The medium-temperature water storage tank 70 is connected to the low-temperature water storage tank 50 through a water cooler 701. The high-temperature water in the high-temperature water storage tank 60 serves as the preheating medium for the first-stage preheating water pipe 51, the second-stage preheating water pipe 53, and the third-stage preheating water pipe 55. After releasing heat, the water then flows into the medium-temperature water storage tank.

[0036] The working principle is as follows: The liquefied air energy storage system described in this application has an energy storage process and an energy release process.

[0037] Energy storage process: This process generally takes place during the off-peak electricity price period at night. Outside air at 0℃~35℃ and atmospheric pressure passes through a first compressor 401 and a first compressor cooler 402, a second compressor 403, and a second compressor cooler 404. After compression and cooling by the two-stage compressor unit, air at a pressure of 1~4MPa, a temperature of 30℃~35℃, and containing free water is formed. This air at 1~4MPa, 30℃~35℃, and containing free water enters the molecular sieve water separator 1 through the separator air inlet pipe 11. The molecular sieve water separator 1 pre-removes the free water generated by compression condensation in the air. The air with free water removed enters the molecular sieve adsorption tower 2 through the separator air outlet pipe 12. The molecular sieve adsorption tower 2 removes carbon dioxide from the air and further removes moisture.

[0038] Air, after carbon dioxide and moisture have been removed from the molecular sieve adsorption tower 2, enters sequentially through the bottom gas inlet 22 into the pre-compressor 405 and pre-cooler 406 of the cold box, where it is pressurized and cooled to form air at 7-10 MPa and 30-35°C. This air is then split into two streams, entering the first air line 31 and the second air line 32 of the cold box 3, where it is cooled. The cooled air discharged from the first air line 31 is liquefied by the first throttle valve 341, and the liquefied air enters the first liquefied air storage tank 4 through the first liquefied air outlet pipe 34 for storage, thus achieving air liquefaction for energy storage. The cooled air discharged from the second air line 32 is liquefied by the second throttle valve 351, and the liquefied air enters the second liquefied air storage tank 8 through the second liquefied air outlet pipe 35 for storage. The liquefied air pressure in the first liquefied air storage tank 4 and the second liquefied air storage tank 8 is 1.9MPa to 2.0MPa, and the temperature is -156℃.

[0039] The liquid air in the second liquefied air storage tank 8 enters the cooling medium liquid air pipeline 36 inside the cold box 3 through the second liquefied air storage tank output pipe 81. The low-temperature air generated by vaporization in the second liquefied air storage tank 8 enters the low-temperature air pipeline 33 inside the cold box 3 through the second liquefied air storage tank low-temperature air output pipe 82. Both the liquid air in the second liquefied air storage tank 8 and the vaporized high-temperature air serve as the cooling medium in the cold box 3. After releasing cold energy from the cooling medium liquid air pipeline 36 and the low-temperature air pipeline 33, the air enters the cold box pre-compressor 405 and merges with the air in the bottom gas connection pipe 22 for further pressurization and cooling.

[0040] In the aforementioned energy storage process, the cooling capacity of the cold box 3 is provided by liquefied natural gas in the LNG pipeline 37, cryogenic nitrogen in the cryogenic nitrogen pipeline 38, liquid air in the cooling medium liquid air pipeline 36, and cryogenic air in the cryogenic air pipeline 33. The use of liquid air and cryogenic air as refrigerants reduces the amount of liquefied natural gas in the LNG pipeline 37 and the amount of cryogenic nitrogen in the cryogenic nitrogen pipeline 38, thereby saving energy.

[0041] During the aforementioned energy storage operation, cold water at a temperature of 20℃±3℃ in the cooling water storage tank 50 is supplied to the first compressor cooler 402, the second compressor cooler 404, and the cold box pre-compressor cooler 406 via the first cooling water output pipe 501, the second cooling water output pipe 502, and the third cooling water output pipe 503, respectively, as a cooling medium to cool the compressed air after each stage. The water that has absorbed heat in the first compressor cooler 402, the second compressor cooler 404, and the cold box pre-compressor cooler 406 enters the high-temperature water storage tank 60 through pipelines from their respective cooling medium outlets. The high-temperature water in the high-temperature water storage tank 60 has a temperature of 200℃±2℃ and a pressure of 2MPa.

[0042] The energy release process is as follows: During peak electricity price periods in the daytime, in order to save electricity, the liquid air stored in the first liquefied air storage tank 4 is used to generate electricity.

[0043] Liquid air in the first liquefied air storage tank 4 is pressurized to 10 MPa to 12 MPa via the liquid air pressurization pump 411 through the first liquefied air storage tank output pipe 41. It then first enters the liquid air-nitrogen heat exchanger 10 to exchange heat with nitrogen, releasing some heat energy. Next, it enters the regeneration gas cooler 20, releasing some heat energy. Afterward, it undergoes three stages of expansion: first-stage expansion preheater 51, first-stage expander 52, second-stage expansion preheater 53, second-stage expander 54, third-stage expansion preheater 55, and third-stage expander 56. The kinetic energy output from the third-stage expander 56 drives a steam turbine to generate electricity, thus realizing the conversion of liquid air energy. The generated electricity can be used by electrical equipment.

[0044] During the above operation, the high-temperature water in the high-temperature water storage tank 60 enters the primary preheating water pipe 6021, secondary preheating water pipe 6022, and tertiary preheating water pipe 6023 respectively into the primary expansion preheater 51, secondary expansion preheater 53, and tertiary expansion preheater 55 to preheat the air that needs to expand. The heat released from the preheating medium outlets of the primary, secondary, and tertiary expansion preheaters 51, 53, and 55 flows through water pipes into the medium-temperature water storage tank 70. The water temperature in the medium-temperature water storage tank 70 is 40℃~60℃. After being cooled by the water cooler 701, the water in the medium-temperature water storage tank 70 flows back into the low-temperature water storage tank 50.

[0045] To regenerate the molecular sieve adsorption tower 2, the air from the air output of the three-stage expander 56 serves as the backflush air for the regeneration of the molecular sieve adsorption tower 2. It first enters the first heater 6 via the hot air delivery pipe 57 for heating. The heating medium in the first heater 6 is high-temperature water from the high-temperature water storage tank 60. The heated high-temperature air then enters the electric heater 7 via the heated medium outlet 62 of the first heater. Because the air temperature sensor 621 is interlocked with the temperature signal of the frequency converter 71, when the air temperature detected by the air temperature sensor 621 does not reach the set value, the frequency converter 71 controls the electric heater 7 to operate and electrically heat the passing air, thereby ensuring that the temperature of the backflush air reaches the set value. High-temperature air from the electric heater 7 enters the molecular sieve adsorption tower 2 via the electric heater output pipe 71, the first check valve 712, the backflush control valve 711, and the bottom gas inlet pipe 22 to heat-blow the bed within the molecular sieve adsorption tower 2. The air containing water and carbon dioxide generated by the heat blowing enters the regeneration gas cooler 20 through the top gas inlet pipe 21 and the regeneration gas output pipe 23 of the molecular sieve adsorption tower 2 for cooling. Finally, it enters the regeneration gas moisture separator 30 to remove water and is discharged from the regeneration gas moisture separator gas outlet pipe 302. The water produced in the regeneration gas moisture separator 30 is discharged from the regeneration gas moisture separator drain pipe 301.

[0046] After hot blowing, cold blowing is performed. Air from the air output of the three-stage expander 56 serves as the backflush air for molecular sieve regeneration in the molecular sieve adsorption tower 2. It enters the molecular sieve adsorption tower 2 via the cold blowing air delivery pipe 58, the second check valve 582, the first check valve 712, the backflush control valve 711, and the bottom gas connection pipe 22 to cold blow the bed within the tower. The gas generated by cold blowing enters the regeneration gas cooler 20 through the top gas connection pipe 21 and the regeneration gas output pipe 23, where it is cooled. Finally, it enters the regeneration gas moisture separator 30 to remove water and is discharged through the regeneration gas moisture separator gas discharge pipe 302. Water produced in the regeneration gas moisture separator 30 is discharged through the regeneration gas moisture separator drain pipe 301.

[0047] After cold blowing and hot blowing, the molecular sieve adsorption tower 2 is regenerated.

[0048] During the release of energy from liquid air, the molecular sieve adsorption tower 2 is regenerated to prepare for liquefied air energy storage during periods of low electricity prices, thereby achieving single-tower adsorption and saving equipment costs.

[0049] Therefore, the liquefied air energy storage system described in this application has the following advantages: 1. By setting up a single molecular sieve adsorption tower and using air from the air output of the expander unit for backflushing to regenerate the molecular sieve adsorption tower, the overall equipment cost is effectively reduced. 2. By using high-temperature water generated by the compressor unit as a heating medium to heat the air used for regeneration of the molecular sieve adsorption tower, thermal energy is fully utilized, effectively saving energy consumption and thus reducing the operating cost of the entire liquefied air energy storage system. 3. The setting and signal interlocking of the electric heater with frequency converter and air temperature sensor ensure that the temperature of the air used for regeneration of the molecular sieve adsorption tower is within the set value, thereby ensuring the efficiency of the molecular sieve adsorption tower regeneration. 4. The entire liquefied air energy storage system has a simple structure, low energy consumption, can store energy during off-peak electricity prices at night and release energy during peak electricity prices during the day, has high energy density, large energy storage capacity, and low operating cost.

Claims

1. A liquid air energy storage system, comprising: The molecular sieve water separator for removing free water in air and the molecular sieve adsorption tower for removing carbon dioxide and water in air are connected with a separator air input pipe, a separator air output pipe and a separator liquid discharge pipe, the separator air input pipe is connected with a compressor set, and the separator air output pipe is connected with a top gas connection pipe of the molecular sieve adsorption tower, characterized in that: a bottom gas connection pipe of the molecular sieve adsorption tower is connected with an air input end of a cold box pre-compressor set, a bottom gas connection pipe control valve is arranged on the bottom gas connection pipe, an air output end of the cold box pre-compressor set is communicated with an inlet of an air pipeline in the cold box, and an outlet of the air pipeline in the cold box is connected with a first liquefied air output pipe provided with a first throttling valve, and the first liquefied air output pipe is connected with a first liquefied air storage tank. A liquid air pressurizing pump is arranged on a first liquefied air storage tank output pipe of the first liquefied air storage tank, an output end of the liquid air pressurizing pump is communicated with an air input end of an expander set, an air output end of the expander set is provided with a hot blow gas delivery pipe provided with a hot blow gas output control valve, a cold blow gas delivery pipe provided with a cold blow gas output control valve and an expander discharge pipe, the hot blow gas delivery pipe is connected with a first heater heated medium inlet of a first heater, a first heater heated medium outlet is connected with an inlet of an electric heater, an outlet of the electric heater is provided with an electric heater output pipe, the electric heater output pipe is connected with the bottom gas connection pipe between the molecular sieve adsorption tower and the bottom gas connection pipe control valve, an output end of the electric heater output pipe is provided with a first check valve and a first back flushing control valve, an output end of the cold blow gas delivery pipe is connected with an output end of the electric heater output pipe, and the output end of the cold blow gas delivery pipe is provided with a second check valve, and a top gas connection pipe of the molecular sieve adsorption tower is connected with a molecular sieve adsorption tower regeneration gas output pipe, and the molecular sieve adsorption tower regeneration gas output pipe is provided with a molecular sieve adsorption tower regeneration gas output control valve.

2. A liquid air energy storage system according to claim 1, wherein: The cold box is further provided with a second air pipeline, the air output end of the cold box pre-compressor set is further communicated with an inlet of the second air pipeline in the cold box, an outlet of the second air pipeline is connected with a second liquefied air output pipe provided with a second throttling valve, the second liquefied air output pipe is connected with a second liquefied air storage tank, a cooling medium liquid air pipeline is arranged in the cold box, a second liquefied air storage tank output pipe on the second liquefied air storage tank is connected with an inlet of the cooling medium liquid air pipeline in the cold box, a low-temperature air pipeline is further arranged in the cold box, a second liquefied air storage tank low-temperature air output pipe on the top of the second liquefied air storage tank is connected with an inlet of the low-temperature air pipeline in the cold box, and the outlet of the cooling medium liquid air pipeline and the outlet of the low-temperature air pipeline are connected with the air input end of the cold box pre-compressor set.

3. A liquid air energy storage system according to claim 1, wherein: The cold box is provided with an LNG pipeline, the inlet of the LNG pipeline is connected with a liquefied natural gas input pipe, and the outlet of the LNG pipeline is connected with a liquefied natural gas output pipe.

4. A liquid air energy storage system according to claim 1, wherein: The cold box is provided with a low-temperature nitrogen pipeline, the inlet of the low-temperature nitrogen pipeline is connected with a nitrogen input pipe, the nitrogen input pipe is connected with a nitrogen cold storage bed, the outlet of the low-temperature nitrogen pipeline is connected with a first nitrogen backflow pipe, the first nitrogen backflow pipe is connected with the nitrogen cold storage bed, and the first nitrogen backflow pipe is provided with a nitrogen first delivery pump.

5. A liquid air energy storage system according to claim 4, wherein: The liquid air nitrogen heat exchanger and the regenerative gas cooler are further arranged between the output end of the liquid air pressurizing pump and the air input end of the expander set, the output end of the liquid air pressurizing pump is connected to the liquid air input end of the liquid air nitrogen heat exchanger, the liquid air output end of the liquid air nitrogen heat exchanger is connected to the inlet of the regenerative gas cooling medium pipeline in the regenerative gas cooler through a pipeline, and the outlet of the regenerative gas cooling medium pipeline in the regenerative gas cooler is connected to the air input end of the expander set; The nitrogen storage bed is provided with a nitrogen output pipe, the nitrogen output pipe is connected to the nitrogen medium heat exchange pipe inlet in the liquid air nitrogen heat exchanger, a second nitrogen delivery pump is arranged on the nitrogen output pipe, and the outlet of the nitrogen medium heat exchange pipe in the liquid air nitrogen heat exchanger is provided with a second nitrogen return pipe, which is connected to the nitrogen storage bed. The regenerative gas output end of the regenerative gas cooler is connected to the regenerative gas moisture separator, the bottom of the regenerative gas moisture separator is provided with a regenerative gas moisture separator liquid discharge pipe, and the regenerative gas moisture separator is provided with a regenerative gas moisture separator gas discharge pipe; the regenerative gas output pipe of the molecular sieve adsorption tower is connected to the regenerative gas input end of the regenerative gas cooler.

6. A liquid air energy storage system according to claim 1, wherein: The compressor set connected to the separator air input pipe is a two-stage compressor set, and the two-stage compressor set comprises, in series, a first compressor and a first compression cooler, a second compressor and a second compression cooler, the air input end of the first compressor is connected to the air source, and the air output end of the second cooler is connected to the separator air input pipe on the molecular sieve moisture separator. The cold box pre-compressor set comprises, in series, a cold box pre-compressor and a cold box pre-compression cooler.

7. A liquid air energy storage system according to claim 6, wherein: The water circulation system comprises a cooling water storage tank, the cooling water storage tank is connected to the cooling medium inlets of the first compression cooler, the second compression cooler and the cold box pre-compression cooler through first, second and third cooling water output pipes respectively, the cooling medium outlets of the first compression cooler, the second compression cooler and the cold box pre-compression cooler are connected to the high-temperature water storage tank through pipelines, the first heater heating medium inlet of the first heater is connected to the high-temperature water storage tank through a first high-temperature water storage tank output pipe, the first heater heating medium outlet of the first heater is connected to the medium-temperature water storage tank through a first heater water outlet pipe, and the first heater water outlet pipe is connected to the medium-temperature water storage tank. The expander set comprises, in series, a first-stage expansion preheater, a first-stage expander, a second-stage expansion preheater, a second-stage expander, a third-stage expansion preheater and a third-stage expander, the high-temperature water storage tank is provided with a second high-temperature water storage tank output pipe, the second high-temperature water storage tank output pipe is connected to the preheating medium inlets of the first-stage expansion preheater, the second-stage expansion preheater and the third-stage expansion preheater through first, second and third preheating water pipes respectively, the preheating medium outlets of the first-stage expansion preheater, the second-stage expansion preheater and the third-stage expansion preheater are connected to the medium-temperature water storage tank through water pipes, and the medium-temperature water storage tank is connected to the low-temperature water storage tank through a water cooler.

8. A liquid air energy storage system according to claim 1 or 7, wherein: The electric heater is provided with a frequency converter, the first heater of the first heater is provided with an air temperature sensor, and the air temperature sensor is connected with the frequency converter temperature signal interlock.

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