Liquid air energy storage system

Abstract

The invention discloses a liquid air energy storage system, which relates to the technical field of liquid air energy storage, and comprises a compressor, a heat storage heat exchanger, a precooler, a first heat exchanger, a second heat exchanger, a throttle valve, a gas-liquid separator and a first ejector, to-be-liquefied air exhausted by the precooler is subjected to heat exchange and cooling in sequence through the first heat exchanger and the second heat exchanger and adiabatic expansion through the throttling valve to reach the gas-liquid separator, the gas-liquid separator is used for separating liquid air and gaseous air, at least part of the gaseous air is conveyed to the first ejector, and at least part of the gaseous air is conveyed to the second ejector. Part of to-be-liquefied air exhausted by the first heat exchanger is conveyed to the first ejector, and first return exhaust air exhausted by the first ejector is conveyed to the air inlet side of the compressor after being subjected to heat exchange through the second heat exchanger. According to the liquid air energy storage system, the loss in the system operation process is reduced, and the energy utilization rate and conversion efficiency of the system are improved.

Description

Technical Field

[0001] This invention relates to the field of liquid air energy storage technology, and more specifically, to a liquid air energy storage system. Background Technology

[0002] Liquid air energy storage (LAES) is an energy storage technology that utilizes off-peak electricity to compress and cryogenically liquefy air for storage, and then vaporizes and expands the liquid air to generate electricity during peak electricity demand. LAES is not limited by geographical conditions, has high energy density, and is environmentally friendly. However, the cycle efficiency of LAES systems is still relatively low, typically 40%-50% for electricity-to-electricity storage. Energy loss during the liquefaction phase (charging process) is particularly significant and is a key factor limiting its economic viability.

[0003] In related technologies, air liquefaction often uses the Claude cycle. Although this cycle introduces a low-temperature expander to perform refrigeration to improve efficiency, it still has inherent thermodynamic irreversible losses, such as throttling losses and heat transfer losses. Summary of the Invention

[0004] The present invention aims to at least partially solve one of the technical problems in the related art.

[0005] To address this, this invention proposes a liquid air energy storage system that reduces energy loss during system operation and improves the system's energy utilization and conversion efficiency.

[0006] The liquid air energy storage system of this invention includes a compressor, a heat storage heat exchanger, a precooler, a first heat exchanger, a second heat exchanger, a throttling valve, a gas-liquid separator, a liquid air storage tank, a first ejector, and a cold storage tank. Air discharged from the compressor exchanges heat with the heat storage medium in the heat storage heat exchanger and then reaches the precooler for precooling. Air to be liquefied discharged from the precooler undergoes sequential heat exchange and cooling in the first and second heat exchangers, and then undergoes adiabatic expansion through the throttling valve before reaching the gas-liquid separator. The gas-liquid separator is used for separation... Liquid air and gaseous air are provided. The liquid air is delivered to the liquid air storage tank, and at least a portion of the gaseous air is delivered to the first ejector. A portion of the air to be liquefied discharged from the first heat exchanger is delivered to the first ejector. The first return air discharged from the first ejector is delivered to the intake side of the compressor after exchanging heat with the air to be liquefied in the second heat exchanger to increase its pressure. The cold storage tank stores a cold storage medium and is used to deliver the cold storage medium to the first heat exchanger and the second heat exchanger to reduce the temperature of the air to be liquefied.

[0007] In some embodiments, a first cryogenic expander is further included, which is located upstream of the first ejector, and the air discharged from the first heat exchanger and delivered to the first ejector is depressurized by the first cryogenic expander.

[0008] In some embodiments, a first flow divider valve is provided upstream of the first cryogenic expander, the first flow divider valve being used to regulate the flow rate of the air to be liquefied delivered from the first heat exchanger to the first ejector.

[0009] In some embodiments, the first exhaust air discharged from the second heat exchanger is delivered to the intake side of the compressor via heat exchange with the air to be liquefied through the first heat exchanger.

[0010] In some embodiments, the first exhaust air discharged from the second heat exchanger exchanges heat with the air to be liquefied via the first heat exchanger and with the air discharged from the precooler and the heat storage heat exchanger, and is then delivered to the intake side of the compressor.

[0011] In some embodiments, a third heat exchanger and a second ejector are also included. The third heat exchanger is disposed between the precooler and the first heat exchanger. A portion of the air to be liquefied discharged from the precooler is conveyed to the first heat exchanger via the third heat exchanger. Another portion of the air to be liquefied discharged from the precooler is conveyed to the second ejector. A portion of the gaseous air is conveyed to the second ejector. The second exhaust air discharged from the second ejector is conveyed to the intake side of the compressor after exchanging heat with the air to be liquefied in the first heat exchanger.

[0012] In some embodiments, a second cryogenic expander is further included, which is located upstream of the second ejector, and the air discharged from the third heat exchanger and delivered to the second ejector is depressurized by the second cryogenic expander.

[0013] In some embodiments, a second flow control valve is provided upstream of the second cryogenic expander, the second flow control valve being used to regulate the flow rate of the air to be liquefied delivered from the third heat exchanger to the second ejector.

[0014] In some embodiments, the second exhaust air discharged from the first heat exchanger is delivered to the intake side of the compressor via the third heat exchanger and / or the precooler.

[0015] In some embodiments, the cold storage tank is provided with a circulation pipeline, and the third heat exchanger, the first heat exchanger and the second heat exchanger are sequentially arranged in the circulation pipeline. The cold storage medium transported in the circulation pipeline passes through the second heat exchanger, the first heat exchanger and the third heat exchanger in sequence to cool the liquefied air.

[0016] The liquid air energy storage system of this invention has the following beneficial effects: 1. By reusing the gaseous air discharged from the gas-liquid separator through the first ejector, the cold energy utilization rate is improved, which can reduce the demand of the first heat exchanger, the second heat exchanger and the third heat exchanger on external cold sources, thereby reducing production costs. At the same time, the first return air discharged by the first ejector can increase the pressure on the compressor intake side, reduce the compression ratio during the compressor operation, improve the compressor's operating efficiency, reduce energy consumption, and reduce operating costs. 2. By using the first heat exchanger, the second heat exchanger, the third heat exchanger, the first ejector, and the second ejector to perform staged cooling and heat exchange of the liquefied air, the temperature difference during heat exchange is reduced, the "pinch" problem is avoided during the heat exchange process, and the heat exchange efficiency and energy utilization efficiency of the system are improved. 3. The low-temperature expander uses part of the air to be liquefied discharged from the first and third heat exchangers to do work, thereby reducing the pressure of the air and cooling it, so as to increase the energy conversion efficiency and improve the system's cooling capacity utilization rate. 4. The flow rate delivered to the cryogenic expander is controlled by the diversion regulating valve, and the diversion ratio is adjusted to adapt to different operating conditions of the system, so as to improve the efficiency of liquefied air and energy conversion and utilization efficiency of the system. Attached Figure Description

[0017] Figure 1 This is a schematic diagram of a liquid air energy storage system according to an embodiment of the present invention.

[0018] Figure label: Compressor 1; Heat storage heat exchanger 2; Precooler 3; First heat exchanger 4; Second heat exchanger 5; Throttling valve 6; Gas-liquid separator 7; Liquid air storage tank 8; First ejector 9; Cold storage tank 10; First heat storage device 11; Second heat storage device 12; First cryogenic expander 13; First flow divider regulating valve 14; Third heat exchanger 15; Second ejector 16; Second cryogenic expander 17; Second flow divider regulating valve 18; Circulation pipeline 19. Detailed Implementation

[0019] Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings. The embodiments described below with reference to the accompanying drawings are exemplary and intended to explain the present invention, and should not be construed as limiting the present invention.

[0020] like Figure 1 As shown, the liquid air energy storage system of this embodiment includes a compressor 1, a heat storage heat exchanger 2, a precooler 3, a first heat exchanger 4, a second heat exchanger 5, a throttle valve 6, a gas-liquid separator 7, a liquid air storage tank 8, a first ejector 9, and a cold storage tank 10.

[0021] The air discharged from compressor 1 is pre-cooled by pre-cooling after exchanging heat with the heat storage medium in heat storage heat exchanger 2. Specifically, the ambient air pressure and temperature increase after the compressor performs work. Heat storage heat exchanger 2 is equipped with heat exchange pipes, which are connected to a first heat storage device 11 and a second heat storage device 12. The heat storage medium in the first heat storage device 11 reaches the heat storage heat exchanger 2 through the heat exchange pipes to absorb the heat from the air discharged from compressor 1. The heat storage medium, after absorbing heat and increasing its temperature, is stored in the second heat storage device 12. The heat stored in the second heat storage device 12 is used to exchange heat with liquid air again during peak electricity demand to increase its temperature, thereby vaporizing and expanding the liquefied air to generate electricity.

[0022] The air to be liquefied discharged from the precooler 3 is cooled down by heat exchange in sequence through the first heat exchanger 4 and the second heat exchanger 5, and then expands adiabatically through the throttle valve 6 to reach the gas-liquid separator 7. The gas-liquid separator 7 is used to separate liquid air and gaseous air. The liquid air is transported to the liquid air storage tank 8, and at least part of the gaseous air is transported to the first ejector 9.

[0023] Specifically, the first heat exchanger 4 is provided with a first channel, a second channel and a third channel, and the second heat exchanger 5 is provided with a fourth channel, a fifth channel and a sixth channel. The air to be liquefied discharged from the precooler 3 is transported to the second channel through a pipeline, the air to be liquefied discharged from the second channel is transported to the fifth channel through a pipeline, and the air to be liquefied discharged from the fifth channel is transported to the throttle valve 6 through a pipeline. After adiabatic expansion by the throttle valve 6, the air to be liquefied is partially liquefied to form a gas-liquid two-phase mixture. The gas-liquid two-phase mixture is separated into liquid air and gaseous air by the gas-liquid separator 7. The gaseous air is transported to the first ejector 9 through a pipeline.

[0024] Part of the air to be liquefied discharged from the first heat exchanger 4 is transported to the first ejector 9. The first return air discharged from the first ejector 9 is transported to the intake side of the compressor 1 after exchanging heat with the air to be liquefied through the second heat exchanger 5 to increase the pressure. The cold storage tank 10 stores the cold storage medium and is used to transport the cold storage medium to the first heat exchanger 4 and the second heat exchanger 5 to reduce the temperature of the air to be liquefied.

[0025] Specifically, the second channel of the first heat exchanger 4 is connected to a pipe connected to the first ejector 9. Part of the air to be liquefied is transported to the first ejector 9 through the pipe and used as working fluid to eject the gaseous air discharged from the gas-liquid separator 7, thereby mixing the two gases and regulating the pressure to generate the first return air. The first return air is transported to the sixth channel through the pipe to cool the air to be liquefied in the fourth channel. The first return air discharged from the sixth channel is transported to the intake side of the compressor 1 through the pipe.

[0026] The cold storage tank 10 delivers cold storage medium to the first and fourth channels through pipelines. The cold storage medium cools the air to be liquefied in the second and fifth channels respectively. When the first return air enters the sixth channel, it can reduce the flow rate of the cold storage medium in the fourth channel and improve the efficiency of cold energy utilization.

[0027] Optionally, an ejector is connected to the intake side of the compressor 1. Ambient air is input into one intake end of the ejector, and the first return exhaust is input into the other intake end of the ejector. The exhaust end of the ejector is connected to the intake port of the compressor 1, which facilitates the pressure adjustment of the intake side of the compressor 1.

[0028] The liquid air energy storage system of this invention reuses the gaseous air discharged from the gas-liquid separator 7 through the first ejector 9, which improves the utilization rate of cold energy and reduces the demand of the second heat exchanger 5 for external cold sources, thereby reducing production costs. At the same time, the first return air discharged by the first ejector 9 can increase the pressure on the intake side of the compressor 1, reduce the compression ratio of the compressor 1 during operation, improve the operating efficiency of the compressor 1, reduce energy consumption, and reduce operating costs.

[0029] It should be noted that generating electricity through liquefied air, liquid pumps, gasification devices, and expander generator sets is existing technology, and its working principle will not be elaborated here.

[0030] In some embodiments, such as Figure 1 As shown, it also includes a first cryogenic expander 13, which is located upstream of the first ejector 9. The air discharged from the first heat exchanger 4 and delivered to the first ejector 9 is depressurized by the first cryogenic expander 13.

[0031] Part of the air to be liquefied discharged from the first heat exchanger 4 is transported through a pipeline to the first cryogenic expander 13. The first cryogenic expander 13 performs work using this part of the air to depressurize and cool the air, thereby reducing the temperature of the first return air after mixing with the gaseous air discharged from the gas-liquid separator 7. This facilitates the cooling of the air to be liquefied in the second heat exchanger 5, thereby increasing energy conversion efficiency and improving the system's cooling capacity utilization rate.

[0032] In some embodiments, such as Figure 1 As shown, a first flow divider valve 14 is provided upstream of the first cryogenic expander 13. The first flow divider valve 14 is used to regulate the flow rate of the air to be liquefied delivered from the first heat exchanger 4 to the first ejector 9.

[0033] The flow rate delivered to the first cryogenic expander 13 is controlled by the first diversion regulating valve 14, which facilitates the control of the pressure and temperature of the first return air to adapt to different operating conditions of the system and improve the efficiency of liquefied air and energy conversion utilization efficiency of the system.

[0034] In some embodiments, the first exhaust air discharged from the second heat exchanger 5 is delivered to the intake side of the compressor 1 via heat exchange with the air to be liquefied through the first heat exchanger 4.

[0035] Specifically, the first exhaust air discharged from the sixth channel is transported to the third channel through a pipeline to further exchange heat and cool the air to be liquefied in the second channel. The first exhaust air in the third channel is transported to the intake side of the compressor 1 through a pipeline to further utilize the cold energy in the first exhaust air, thereby reducing the flow rate of the cold storage medium in the first channel and improving the efficiency of cold energy utilization.

[0036] In some embodiments, the first return air discharged from the second heat exchanger 5 exchanges heat with the air to be liquefied via the first heat exchanger 4 and the air discharged from the precooler 3 and the heat storage heat exchanger 2, and is then transported to the intake side of the compressor 1.

[0037] Specifically, the first return air discharged from the sixth channel is transported to the third channel through a pipeline to further exchange heat and cool the air to be liquefied in the second channel. The first return air in the third channel is transported to the precooler 3 through a pipeline. The first return air serves as the heat exchange medium for the precooler 3. The first return air discharged from the precooler 3 is transported to the intake side of the compressor 1 to further utilize the cold energy in the first return air. This reduces the flow rate of the cold storage medium in the first channel and replaces the heat exchange medium in the precooler 3, thereby reducing dependence on external cold sources and improving the efficiency of cold energy utilization.

[0038] In some embodiments, such as Figure 1 As shown, it also includes a third heat exchanger 15 and a second ejector 16. The third heat exchanger 15 is located between the precooler 3 and the first heat exchanger 4. A portion of the air to be liquefied discharged from the precooler 3 is transported to the first heat exchanger 4 via the third heat exchanger 15. Another portion of the air to be liquefied discharged from the precooler 3 is transported to the second ejector 16. A portion of the gaseous air is transported to the second ejector 16. The second return air discharged from the second ejector 16 is transported to the intake side of the compressor 1 after exchanging heat with the air to be liquefied in the first heat exchanger 4.

[0039] Specifically, the third heat exchanger 15 is provided with a seventh channel, an eighth channel, and a ninth channel. The air to be liquefied discharged from the precooler 3 passes through the eighth channel, the second channel, and the fifth channel in sequence for heat exchange and cooling. Part of the air to be liquefied discharged from the eighth channel is transported to the second ejector 16 through a pipeline. Part of the gaseous air discharged from the gas-liquid separator 7 is transported to the first ejector 9 through a pipeline. Another part of the gaseous air discharged from the gas-liquid separator 7 is transported to the second ejector 16 through a pipeline. The two air streams are mixed and regulated by the second ejector 16 to generate the second return air. The second return air is transported to the third channel through a pipeline to exchange and cool the air to be liquefied in the second channel. The second return air discharged from the third channel is transported to the air inlet side of the compressor 1 through a pipeline. The cold storage tank 10 transports the cold storage medium to the seventh channel through a pipeline. The cold storage medium cools the air to be liquefied in the eighth channel. When the second return air enters the third channel, the flow rate of the cold storage medium in the seventh channel can be reduced, thereby improving the efficiency of cold energy utilization.

[0040] By using the first heat exchanger 4, the second heat exchanger 5, the third heat exchanger 15, the first ejector 9, and the second ejector 16 to perform staged cooling and heat exchange of the liquefied air, the temperature difference during heat exchange is reduced, the "pinch" problem is avoided during the heat exchange process, and the heat exchange efficiency and energy utilization efficiency of the system are improved.

[0041] In some embodiments, such as Figure 1 As shown, it also includes a second cryogenic expander 17, which is located upstream of the second ejector 16. The air discharged from the third heat exchanger 15 and delivered to the second ejector 16 is depressurized by the second cryogenic expander 17.

[0042] Part of the air to be liquefied discharged from the third heat exchanger 15 is transported to the second cryogenic expander 17 through a pipeline. The second cryogenic expander 17 uses this part of the air to do work to reduce pressure and cool down, thereby reducing the temperature of the second return air after mixing with the gaseous air discharged from the gas-liquid separator 7. This facilitates the cooling of the air to be liquefied in the first heat exchanger 4, thereby increasing energy conversion efficiency and improving the system's cooling capacity utilization rate.

[0043] In some embodiments, such as Figure 1 As shown, a second flow divider valve 18 is provided upstream of the second cryogenic expander 17. The second flow divider valve 18 is used to regulate the flow rate of the air to be liquefied, which is delivered from the third heat exchanger 15 to the second ejector 16.

[0044] The flow rate delivered to the second cryogenic expander 17 is controlled by the second diversion regulating valve 18, which facilitates the control of the pressure and temperature of the second return air to adapt to different operating conditions of the system and improve the efficiency of liquefied air and energy conversion utilization.

[0045] In some embodiments, the second exhaust air discharged from the first heat exchanger 4 is delivered to the intake side of the compressor 1 via the third heat exchanger 15 and / or the precooler 3.

[0046] Specifically, the second exhaust air discharged from the third channel is transported to the ninth channel through a pipeline and then to the intake side of the compressor 1 through a pipeline; or the second exhaust air discharged from the third channel is transported to the precooler 3 through a pipeline and then to the intake side of the compressor 1 through a pipeline; or the second exhaust air discharged from the third channel is transported to the intake side of the compressor 1 through the ninth channel and the precooler 3 in sequence, thereby further utilizing the cold energy in the second exhaust air to reduce the flow rate of the cold storage medium in the first channel and improve the efficiency of cold energy utilization.

[0047] Optionally, the ninth, third, and sixth channels are connected in sequence by pipes to form a return and exhaust pipeline. The first and second return and exhaust air are both transported to the precooler 3 through the return and exhaust pipeline to further increase the utilization rate of the cooling capacity of the system and improve the cooling efficiency of the system for liquefied air.

[0048] The liquefaction process in this embodiment of the invention: The ambient air entering the compressor 1 has a pressure of 0.1 MPa and a temperature of 25°C. The pressure of the high-pressure gas after being compressed by the compressor 1 is generally 5.0 MPa. The heat generated during the compression process is exchanged with the heat storage medium at the heat storage heat exchanger 2 and stored in the second heat storage device 12. The air discharged from the heat storage heat exchanger 2 is initially cooled at the precooler 3 and then sequentially enters the third heat exchanger 15, the first heat exchanger 4, and the second heat exchanger 5 for segmented heat exchange and cooling.

[0049] After the liquefied air passes through the third heat exchanger 15, it is discharged at a temperature of approximately -110°C. Optionally, approximately 10% of the total flow rate of the liquefied air is delivered to the second ejector 16 via the first diversion regulating valve 14. It should be noted that the total flow rate refers to the flow rate of the liquefied air discharged from the precooler 3. Approximately 90% of the total flow rate of the liquefied air discharged from the third heat exchanger 15 is delivered to the first heat exchanger 4. After being cooled by heat exchange in the first heat exchanger 4, the liquefied air is discharged at a temperature of approximately -160°C. Optionally, approximately 15% of the total flow rate of the liquefied air is delivered to the first ejector 9 via the second diversion regulating valve 18. Approximately 75% of the total flow rate of the liquefied air discharged from the first heat exchanger 4 is delivered to the second heat exchanger 5. After being cooled by heat exchange in the second heat exchanger 5, the liquefied air is discharged at a temperature of approximately -190°C and delivered to the throttle valve 6. At this point, the pressure is approximately 5.0. The air to be liquefied, at a pressure of MPa and a temperature of approximately -190°C, expands adiabatically to 0.1 MPa at the throttle valve 6. Due to the Joule-Thomson effect, the temperature drops sharply to -196°C and partial liquefaction occurs. The gas-liquid two-phase mixture enters the gas-liquid separator 7. Inside the gas-liquid separator 7, the liquid air settles to the bottom due to gravity and is transported to the liquid air storage tank 8 for storage. The unliquefied gaseous air at the top, with a pressure of 0.1 MPa and a temperature of -196°C, is then transported to the first ejector 9 and the second ejector 16, respectively.

[0050] Approximately 10% of the total flow of the air to be liquefied is transported to the second ejector 16 via the second cryogenic expander 17. After expansion and work done by the first cryogenic expander 13, this portion of the air to be liquefied outputs air with a pressure of approximately 0.4 MPa and a temperature of approximately -150°C. This air is then mixed and pressurized with the gaseous air discharged from the gas-liquid separator 7 in the second ejector 16 to obtain a second return gas with a pressure of approximately 0.21 MPa and a temperature of approximately -145°C. The second return gas exchanges heat countercurrently with the air to be liquefied in the first heat exchanger 4, which has a mainstream temperature of -130°C to -140°C. Since the temperature of the second return air (-145°C) is lower than the mainstream temperature (-130°C to -140°C) in this region, heat transfer is improved, the temperature matching of the first heat exchanger 4 is optimized, and the "pinch point" problem in this region is significantly alleviated.

[0051] Approximately 15% of the total flow of the air to be liquefied is transported to the first ejector 9 via the first cryogenic expander 13. After expansion and work done by the first cryogenic expander 13, this portion of the air to be liquefied outputs air with a pressure of approximately 0.25 MPa and a temperature of approximately -185°C. This air is then mixed and pressurized with the gaseous air discharged from the gas-liquid separator 7 in the first ejector 9 to obtain a first return gas with a pressure of approximately 0.16 MPa and a temperature of approximately -175°C. The first return gas undergoes countercurrent heat exchange with the air to be liquefied in the second heat exchanger 5, which has a mainstream temperature of -165°C to -170°C. Since the temperature of the first return air (-175°C) is lower than the mainstream temperature (-165°C to -170°C) in this region, the heat exchange efficiency at extremely low temperatures is improved, further alleviating or eliminating the "pinch" problem in this region.

[0052] The first and second exhaust gases are transported to the precooler 3 through pipelines and used as the heat exchange medium in the precooler 3. Finally, they are transported to the intake side of the compressor 1 through pipelines. The pressure of the first and second exhaust gases after mixing is 0.15-0.20 MPa, which increases the pressure on the intake side of the compressor 1 and reduces the compression ratio and compression power consumption of the compressor 1.

[0053] In some embodiments, such as Figure 1 As shown, the cold storage tank 10 is provided with a circulation pipeline 19. The third heat exchanger 15, the first heat exchanger 4 and the second heat exchanger 5 are sequentially arranged in the circulation pipeline 19. The cold storage medium transported in the circulation pipeline 19 passes through the second heat exchanger 5, the first heat exchanger 4 and the third heat exchanger 15 in sequence to cool the liquefied air.

[0054] The pipelines for conveying the cold storage medium on the third heat exchanger 15, the first heat exchanger 4, and the second heat exchanger 5 are connected in sequence to reduce the number of pipelines and the loss of cold storage medium during the transportation process. This also reduces the temperature difference between the cold storage medium and the air to be liquefied when they exchange heat and cool down in the third heat exchanger 15, the first heat exchanger 4, and the second heat exchanger 5, thus avoiding the occurrence of "pinch points" and improving the heat exchange efficiency and energy utilization efficiency of the system.

[0055] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," "outer," "clockwise," "counterclockwise," "axial," "radial," and "circumferential" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0056] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0057] In this invention, unless otherwise explicitly specified and limited, the terms "installation," "connection," "linking," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection, an electrical connection, or a connection that allows communication between them; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components, unless otherwise explicitly limited. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0058] In this invention, unless otherwise explicitly specified and limited, "above" or "below" the second feature can mean that the first feature is in direct contact with the second feature, or that the first feature is in indirect contact with the second feature through an intermediate medium. Furthermore, "above," "over," and "on top" of the second feature can mean that the first feature is directly above or diagonally above the second feature, or simply that the first feature is at a higher horizontal level than the second feature. "Below," "below," and "under" the second feature can mean that the first feature is directly below or diagonally below the second feature, or simply that the first feature is at a lower horizontal level than the second feature.

[0059] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0060] Although embodiments of the present invention have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of the present invention.

Claims

1. A liquid air energy storage system, characterized in that, It includes a compressor, a heat storage heat exchanger, a precooler, a first heat exchanger, a second heat exchanger, a throttle valve, a gas-liquid separator, a liquid air storage tank, a first ejector, and a cold storage tank; The air discharged from the compressor exchanges heat with the heat storage medium in the heat storage heat exchanger and then reaches the precooler for precooling. The air to be liquefied discharged from the precooler exchanges heat and cools down in sequence through the first heat exchanger and the second heat exchanger, and then expands adiabatically through the throttle valve to reach the gas-liquid separator. The gas-liquid separator is used to separate liquid air and gaseous air. The liquid air is delivered to the liquid air storage tank, and at least part of the gaseous air is delivered to the first ejector. A portion of the air to be liquefied discharged from the first heat exchanger is delivered to the first ejector. The first return air discharged from the first ejector is delivered to the intake side of the compressor after exchanging heat with the air to be liquefied in the second heat exchanger to increase the pressure. The cold storage tank stores a cold storage medium and is used to deliver the cold storage medium to the first heat exchanger and the second heat exchanger to reduce the temperature of the air to be liquefied.

2. The liquid air energy storage system according to claim 1, characterized in that, It also includes a first cryogenic expander, which is located upstream of the first ejector. The air discharged from the first heat exchanger and delivered to the first ejector is depressurized by the first cryogenic expander.

3. The liquid air energy storage system according to claim 2, characterized in that, The first cryogenic expander is provided with a first flow divider valve upstream, which is used to regulate the flow rate of the air to be liquefied delivered from the first heat exchanger to the first ejector.

4. The liquid air energy storage system according to claim 1, characterized in that, The first return air discharged from the second heat exchanger is delivered to the intake side of the compressor after exchanging heat with the air to be liquefied through the first heat exchanger.

5. The liquid air energy storage system according to claim 1, characterized in that, The first return air discharged from the second heat exchanger exchanges heat with the air to be liquefied through the first heat exchanger and with the air discharged from the precooler and the heat storage heat exchanger, and is then transported to the intake side of the compressor.

6. The liquid air energy storage system according to any one of claims 1-5, characterized in that, It also includes a third heat exchanger and a second ejector. The third heat exchanger is located between the precooler and the first heat exchanger. A portion of the air to be liquefied discharged from the precooler is transported to the first heat exchanger via the third heat exchanger. Another portion of the air to be liquefied discharged from the precooler is transported to the second ejector. A portion of the gaseous air is transported to the second ejector. The second return air discharged from the second ejector is transported to the intake side of the compressor after exchanging heat with the air to be liquefied in the first heat exchanger.

7. The liquid air energy storage system according to claim 6, characterized in that, It also includes a second cryogenic expander, which is located upstream of the second ejector. The air discharged from the third heat exchanger and delivered to the second ejector is depressurized by the second cryogenic expander.

8. The liquid air energy storage system according to claim 7, characterized in that, A second flow divider valve is provided upstream of the second cryogenic expander. The second flow divider valve is used to regulate the flow rate of the air to be liquefied, which is delivered from the third heat exchanger to the second ejector.

9. The liquid air energy storage system according to claim 6, characterized in that, The second exhaust air discharged from the first heat exchanger is delivered to the intake side of the compressor via the third heat exchanger and / or the precooler.

10. The liquid air energy storage system according to claim 6, characterized in that, The cold storage tank is equipped with a circulation pipeline. The third heat exchanger, the first heat exchanger and the second heat exchanger are sequentially arranged in the circulation pipeline. The cold storage medium transported in the circulation pipeline passes through the second heat exchanger, the first heat exchanger and the third heat exchanger in sequence to cool the liquefied air.

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