Variable load liquid air compression energy storage system

Abstract

The invention provides a variable-load liquid air compression energy storage system which is characterized in that target to-be-liquefied air is subjected to shunting treatment through a main cold box with a shunting function, then the shunted air is subjected to secondary pressurization and then is subjected to throttling cooling, that is, the refrigeration mode that the shunted air is subjected to secondary pressurization and then is subjected to throttling is adopted; the cold source needed by air liquefaction is supplemented, when the energy storage duration of the system is increased, a certain cooling capacity can be provided as long as shunting air exists, the running duration range of the system is widened, and the load range of the system is widened; in addition, by changing the proportion of the split air to the main air, the supplied cooling capacity can be increased, and the overall liquefaction rate of the system air can be guaranteed.

Description

Technical Field

[0001] The present disclosure relates to the technical field of air compression energy storage, and in particular to a variable load liquid air compression energy storage system. Background Art

[0002] Liquid air energy storage is derived from compressed air energy storage technology, and both use air as the main energy storage material. Liquid compressed air energy storage technology mainly utilizes the liquefied phase change characteristics of air. Unlike compressed air energy storage, the compressed gas in liquid air energy storage does not enter the gas storage chamber, but enters the liquefaction unit, so that the gaseous air is converted into liquid air for storage. The gas storage required for liquid air is small in volume and occupies a small area. The main process includes: during the period of low electricity consumption, the abandoned wind and photovoltaic power or low-valley electricity is used to drive the motor, and the ambient air is compressed, cooled, liquefied and stored in a low-temperature storage tank with the help of a compressor and a cold storage device; during the peak electricity consumption, the liquefied compressed air in the storage tank is pressurized and heated, and the liquid air enters the expander after gasification to do work, thereby driving the generator to generate electricity.

[0003] However, the existing technology requires a certain amount of cold energy in the liquefaction cooling process of compressed air. How to provide sufficient liquefaction cooling source and improve the load range of the system has become a problem. Summary of the invention

[0004] In view of this, an embodiment of the present disclosure provides a variable load liquid air compression energy storage system, which at least partially solves the problems existing in the prior art.

[0005] The embodiment of the present disclosure provides a variable load liquid air compression energy storage system, comprising:

[0006] A variable load liquid air compression energy storage system comprises an air compression unit, a liquefaction unit, and an energy release unit, wherein the liquefaction unit comprises:

[0007] A main cold box with a flow-dividing function, a liquid expander, a fourth air compressor, a second throttle valve, a gas-liquid separator, and a liquid air storage tank; the main cold box is connected to the liquid expander, the gas-liquid separator, and the liquid air storage tank in sequence through pipelines; the main cold box is connected to the fourth air compressor, and a second flow-dividing valve is arranged between the main cold box and the fourth air compressor;

[0008] The main cold box with a diversion function is used to separate the target air to be liquefied obtained by compression of the air compression unit into mainstream air and diversion air, and liquefy the target air to be liquefied when the target air to be liquefied passes through the main cold box; after the mainstream air enters the liquid expander, the liquid air is stored in a liquid air storage tank through a gas-liquid separator; the diversion air is pressurized by the fourth air compressor and diverted by the second diversion valve, and then returned to the main cold box for cooling.

[0009] Optionally, the liquid expander is connected to the fourth air compressor via a connecting rod, so that the liquid expander can drive the fourth air compressor to pressurize the diverted air.

[0010] Optionally, the fourth air compressor is a small air compressor.

[0011] Optionally, the main cold box is connected to a fourth air compressor and a gas-liquid separator through a three-way pipe, and the second diverter valve is arranged between the three-way pipe connection and the fourth air compressor; the diverted air is pressurized by the fourth air compressor and diverted by the second diverter valve, and then mixed with the return air from the gas-liquid separator and returned to the main cold box for cooling.

[0012] Optionally, the main cold box is provided with a diversion switch for controlling the flow rates of mainstream air and diversion air.

[0013] Optionally, the cold energy used by the main cold box to liquefy the target air to be liquefied comes from a circulating refrigeration unit:

[0014] The circulating refrigeration unit is used to provide high-quality cold by using the cold stored in the cold storage subunit through the use of deep-cold refrigerant; the cold stored in the cold storage subunit comes from the cold brought by the temperature drop when the liquefied air stored in the liquefaction unit expands and releases energy during the energy release stage.

[0015] Optionally, the refrigeration cycle unit includes a cryogenic refrigerant, a condenser, a first throttle valve, and a third air compressor; the condenser, the first throttle valve, a main cold box of the liquefaction unit, and the third air compressor are connected in a loop in sequence;

[0016] The deep cold refrigerant of the refrigeration cycle unit is condensed by the condenser using the cold stored in the cold storage subunit, and after passing through the first throttle valve, the temperature is reduced to a temperature lower than the temperature of the cold storage medium in the cold storage subunit, thereby providing high-quality cold for the main cold box of the liquefaction unit; the main cold box is used to liquefy the target air to be liquefied when it passes through;

[0017] The third air compressor is used to pressurize the cryogenic refrigerant that has been vaporized after passing through the main cold box, and compress it to the condenser for recycling.

[0018] The present disclosure provides a variable load liquid air compression energy storage system, comprising an air compression unit, a liquefaction unit, and an energy release unit, wherein the liquefaction unit comprises: a main cold box with a diversion function, a liquid expansion machine, a fourth air compressor, a second throttle valve, a gas-liquid separator, and a liquid air storage tank; the main cold box is connected to the liquid expansion machine, the gas-liquid separator, and the liquid air storage tank in sequence through pipelines; the main cold box is connected to the fourth air compressor, and a second diversion valve is arranged between the main cold box and the fourth air compressor; wherein the main cold box with a diversion function is used to separate the target air to be liquefied obtained by compression of the air compression unit into mainstream air and diversion air, and liquefy the target air to be liquefied when the target air to be liquefied passes through the main cold box; wherein after the mainstream air enters the liquid expansion machine, the liquid air is stored in the liquid air storage tank through the gas-liquid separator; the diversion air is pressurized by the fourth air compressor and diverted by the second diversion valve, and then returns to the main cold box for cooling. That is, the target air to be liquefied is diverted through a main cold box with a diversion function, and then the diverted air is secondary pressurized and then throttled for cooling. In other words, a refrigeration method of secondary pressurization and then throttling of the diverted air is adopted, which increases the available cooling capacity of the system and realizes the supplement of the cold source required for air liquefaction. In addition, as long as there is diverted air, cold energy can be provided by secondary pressurization and then throttling of the diverted air, which expands the operating time range of the system and increases the load range of the system.

[0019] In order to make the above-mentioned objectives, features and advantages of the present disclosure more obvious and easy to understand, preferred embodiments are specifically cited below and described in detail with reference to the attached drawings. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] In order to more clearly illustrate the technical solutions of the embodiments of the present disclosure, the following is a brief introduction to the drawings required for use in the embodiments. The drawings herein are incorporated into the specification and constitute a part of the specification. These drawings illustrate embodiments consistent with the present disclosure and are used together with the specification to illustrate the technical solutions of the present disclosure. It should be understood that the following drawings only illustrate certain embodiments of the present disclosure and should not be regarded as limiting the scope. For ordinary technicians in this field, other relevant drawings can also be obtained based on these drawings without creative work.

[0021] Figure 1 It is a schematic diagram of a variable load liquid air compression energy storage system provided in an embodiment of the present disclosure.

[0022] The description of the figures is as follows:

[0023] 1-first air compressor; 2-second air compressor; 3-first heat exchanger; 4-second heat exchanger,

[0024] 5-condenser; 6-main cold box; 7-third air compressor, 8-first throttle valve; 9-liquid expander; 10-second throttle valve; 11-fourth air compressor; 12-gas-liquid separator; 13-liquid air storage tank; 14-liquid air booster pump; 15-third heat exchanger; 16 fourth heat exchanger; 17-expander; 18-cold energy storage tank hot tank; 19-cold energy storage tank cold tank; 20-thermal energy storage tank hot tank; 21-thermal energy storage tank cold tank. DETAILED DESCRIPTION

[0025] The following describes the implementation methods of the embodiments of the present disclosure through specific specific examples. Those skilled in the art can easily understand other advantages and effects of the embodiments of the present disclosure from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all of the embodiments. The embodiments of the present disclosure can also be implemented or applied through other different specific implementation methods, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the embodiments of the present disclosure. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict. Based on the embodiments in the embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without making creative work belong to the scope of protection of the embodiments of the present disclosure.

[0026] The present disclosure provides a variable load liquid air compression energy storage system, such as Figure 1 As shown, including:

[0027] Air compression unit, heat storage sub-unit, air liquefaction unit, refrigeration cycle unit, energy release unit, cold storage sub-unit.

[0028] The air compression unit includes: a first air compressor 1, a first heat exchanger 3, a second heat exchanger 4, a second air compressor 2, a heat storage tank hot tank 20, and a heat storage tank cold tank 21. The first air compressor 1, the first heat exchanger 3, the second heat exchanger 4, and the second air compressor 2 are connected in sequence by pipelines. The first air compressor 1 is used to compress the compressed air to obtain high-pressure and high-temperature air. The first heat exchanger 3 is a water-air cooling heat exchanger, which is used to store heat using the high-temperature air compressed by the first air compressor. The heat storage medium in the heat storage tank cold tank 21 absorbs heat through the first compressor and is stored in the heat storage tank hot tank 20. The heat storage medium in the heat storage tank hot tank can be water or other media that can realize the function of the present application. The second heat exchanger 4 is a propane-air heat exchanger, which is used to further cool the air treated by the first heat exchanger to obtain air to be further compressed, which is low-temperature air. The cold stored in the cold storage subunit can be used as the cold source for the second heat exchanger 4 to further cool the compressed air; specifically, the cold stored in the cold storage tank 19 of the cold storage subunit is used by the refrigeration cycle unit and then sent to the second heat exchanger, so as to achieve full and effective utilization of the cold stored in the cold storage subunit, wherein the temperature of the cold medium (such as propane, or other cold medium that can realize the function of the present application) stored in the cold storage tank 19 of the cold storage subunit is still relatively low after passing through the refrigeration cycle unit, and can be used to cool the air to be further compressed; or it can be directly transmitted from the cold storage subunit. The second air compressor 2 is a low-temperature air compressor, which is used to further compress the air to be further compressed to obtain air to be liquefied. Among them, the air compression unit includes a heat storage subunit, including: a heat storage medium hot storage tank 20, a first heat exchanger 3, and a heat storage medium cold storage tank 21; the heat storage medium in the heat storage medium cold storage tank 21 absorbs heat through the first heat exchanger and is stored in the heat storage medium hot storage tank 20.

[0029] The air liquefaction unit includes: a main cold box 6, a liquid expansion machine 9, a fourth air compressor 11, a second throttle valve 10, a gas-liquid separator 12, and a liquid air storage tank 13. Among them, the fourth air compressor 11 is a small air compressor. The main cold box 6 uses the cold capacity provided by the refrigeration cycle unit to liquefy the air to be liquefied (gas-liquid two-phase), and diverts the passing air to be liquefied into mainstream air and diverted air; wherein, after the mainstream air enters the liquid expansion machine 9, the liquid air is stored in the liquid air storage tank 13 through the gas-liquid separator 12. Among them, the diverted air uses the energy of the liquid expansion machine 9 to drive the fourth air compressor 11 (small air compressor) for further pressurization, and then mixes with the return air at the top of the gas-liquid separator 12, returns to the main cold box for cooling, and finally returns to the inlet of the second compressor 2. Among them, a second throttle valve 10 is set between the fourth compressor 11 and the return channel of the main cold box, which is used to further reduce the temperature of the return air and provide cold energy for the main cold box. That is, as long as there is diverted air, cold energy can be provided for the main cold box. Even if the cold energy of the propane cold tank (cold energy storage tank cold tank 19) is fully utilized, cold energy can be provided by secondary pressurization and then throttling of the diverted air, so as to avoid the system being unable to provide additional cold energy when the energy storage time needs to be increased due to the limited cold energy provided by the cold storage unit, so that the system's workload variation range is greatly reduced, thereby realizing the variable load operation of the system. Among them, the liquid expander 9 is connected to the fourth air compressor 11 with a connecting rod, that is, the energy of the liquid expander is utilized, and there is no need to provide additional energy to the fourth air compressor, so that the energy utilization rate of the liquid expander can be fully utilized. Specifically, the main cold box is connected to the fourth air compressor and the gas-liquid separator through a three-way pipe, and the second diverter valve is arranged between the three-way pipe connection and the fourth air compressor; the diverted air is pressurized by the fourth air compressor and diverted by the second diverter valve, and then mixed with the return air of the gas-liquid separator and returned to the main cold box for cooling. Specifically, the main cold box is provided with a diverter switch for controlling the flow of the mainstream air and the diverted air.

[0030] The refrigeration cycle unit includes: a condenser 5, a third air compressor 7, and a first throttle valve 8. The condenser 5, the first throttle valve 6, the main cold box 6 of the liquefaction unit, and the third air compressor 7 are connected in sequence, that is, the third air compressor 7 is also connected to the condenser 5. The condenser is used to realize the condensation of the deep cold refrigerant. The condenser 5 is connected to the propane cold tank 19 of the cold storage subunit, so that the cold stored in the cold storage subunit can be used. The cold stored in the cold storage subunit is used as the high temperature end of the refrigeration cycle. The deep cold refrigerant of the refrigeration cycle unit is condensed by the condenser 5 to reduce the available temperature of the deep cold refrigerant, and then the temperature of the deep cold refrigerant is further reduced through the first throttle valve (after passing through the throttle valve, the pressure and temperature of the deep cold refrigerant are reduced), and the temperature is reduced to a temperature lower than the temperature of the cold storage medium in the cold storage subunit, so as to obtain high-quality cold, thereby meeting the demand for air liquefaction and improving the air liquefaction rate.

[0031] The energy release unit includes: an air booster pump 14, an air expander 17, a third heat exchanger 15, and a fourth heat exchanger 16. The air booster pump 14, the third heat exchanger 15, the fourth heat exchanger 16, and the expander 17 are connected in sequence. In the energy release stage, the liquid air in the liquid air storage tank 13 is pressurized by the air booster pump 14, the third heat exchanger 15 (cold storage heat exchanger), and then passes through the fourth heat exchanger 16 (water-air heat exchanger), and then enters the expander 17 to generate electricity, and transmits the electricity to the power grid.

[0032] Among them, the energy release unit includes a cold storage sub-unit, and the cold storage sub-unit includes: an air-propane heat exchanger 15 (the third heat exchanger), a cold storage tank cold tank 19 (propane cold storage tank), and a cold storage tank hot tank 18 (propane hot storage tank); the cold storage tank hot tank 18, the third heat exchanger, and the cold storage tank cold tank 19 are connected in sequence, and the connection direction is opposite to the expansion flow direction of the air when the liquid air releases energy.

[0033] In the energy release stage, the heat stored in the heat storage hot tank 20 is used to heat the air through the heat exchanger 16, and then stored in the heat storage cold tank 21 for use in the energy storage stage and heat storage cycle.

[0034] The present disclosure provides a variable load liquid air compression energy storage system, comprising: an air compression unit, a liquefaction unit, at least one refrigeration cycle unit, and a cold storage subunit; the air compression unit is used to compress the air to be liquefied to obtain the target air to be liquefied; the liquefaction unit is used to liquefy and store the target air to be liquefied by using the cold provided by the refrigeration cycle unit; wherein the refrigeration cycle unit is used to use the cold stored in the cold storage subunit to provide high-quality cold by using the deep cold refrigerant used; the cold stored in the cold storage subunit comes from the cold brought by the temperature reduction when the liquefied air stored in the liquefaction unit expands and releases energy in the energy release stage. That is, the cold stored in the cold storage subunit serves as the high temperature end of the refrigeration cycle, and the temperature of the deep cold storage agent used is lower than the temperature of the cold storage medium of the cold storage subunit through the refrigeration cycle unit, thereby providing high-quality cold and improving the air liquefaction rate; at the same time, since the cold used comes from the cold brought by the temperature reduction when the liquefied air stored in the liquefaction unit expands and releases energy in the energy release stage, the additional energy consumption of the system is reduced.

[0035] The present disclosure provides a possible implementation method, wherein the variable load liquid air compression energy storage system comprises:

[0036] It includes two refrigeration cycle units (not shown in the figure), and the cold storage tank 19 of the refrigeration unit is connected to the condensers of the two refrigeration cycle units in sequence to provide cold energy for the two refrigeration cycle units. That is, after the cold storage tank 19 of the refrigeration unit is connected to the condenser 1 to provide cold energy, the storage coolant passes through the condenser 2 to provide cold energy for the second refrigeration cycle. The corresponding liquefaction unit includes two main cold boxes connected in series, and each main cold box is respectively connected to a corresponding refrigeration cycle unit.

[0037] Specifically, the two refrigeration cycle units respectively use different cryogenic refrigerants or cryogenic refrigerant mixtures; wherein the cryogenic refrigerant used by the refrigeration cycle unit on the liquefied air storage tank side of the liquefaction unit can reach a lower minimum temperature than the cryogenic refrigerant used by the other refrigeration cycle unit. The cryogenic refrigerant can be at least one of the following or a mixture of more than one: hydrogen, helium, ammonia, and freon.

[0038] The disclosed embodiment realizes full utilization of the cold storage capacity of the cold storage unit. In addition, the liquefaction rate of air can be improved by two main cold boxes connected in series corresponding to the two-stage refrigeration cycle.

[0039] For example, in combination Figure 1 Explain the changes in air or refrigerant pressure and temperature during the energy storage and release process of the compressed energy storage system. Figure 1A- stands for air; P- stands for cold storage medium; C- stands for cryogenic refrigerant. It should be noted that the following is only an exemplary description, and the parameters vary depending on the equipment used, the temperature, pressure, air volume, etc.

[0040] 1. The air is initially compressed to 2 MPa by compressor 1 and absorbed by heat exchanger 2 to store the compression heat in the heat storage medium and stored in heat tank 20;

[0041] 2. The air will be cooled to room temperature (about 30°C) by heat exchanger 3 and become A1. Then it will be combined with downstream return air A2 (temperature is about -30°C) to become A13, and then pass through heat exchanger 4 to absorb low-grade cold (-70°C) from the cold storage medium and enter air booster 2 to be pressurized to about 8MPa. The temperature at this time is about 0°C.

[0042] 3. The air is divided into two streams:

[0043] One stream is the bypass air A4, which is cooled to about -110°C by the heat exchanger 6, and then compressed by the small compressor 11 to become A9 (temperature about -100°C, pressure 10MPa), and then cooled and reduced in pressure by the throttle valve 10 to become low-temperature air A10 of about 2MPa and temperature of -150°C; (the purpose of the bypass air is to provide cooling capacity, which accounts for more than 50% of the air liquefaction)

[0044] The other stream is the mainstream air A3, which is cooled to about -140°C A6 by the heat exchanger 6, and then cooled and reduced in pressure by the expander 9 to become A7 (temperature -150°C, pressure 2MPa, and gas-liquid coexistence state), and then separated by the gas-liquid separator 12, and the liquid air product A12 flows into the liquid air storage tank 13 for storage. The gaseous product A8 returns and mixes with the diverted air throttling gas A10; (the purpose of the mainstream air is to produce liquid air products)

[0045] 4. The low-temperature air A11 (temperature -150°C, pressure 2MPa) after A10 is mixed with the return air A8 from the gas-liquid separator 12 and returns to the heat exchanger 6 for cooling.

[0046] 5. Regarding the use of cold storage medium cooling capacity:

[0047] During the energy release process, the cold storage medium absorbs the cold energy from the liquid air A13 and stores it in the cold tank 19 (temperature is about -145℃).

[0048] During the refrigeration cycle, the cryogenic refrigerant C1 (temperature -140°C, pressure 1MPa) becomes C2 (temperature -160°C, pressure 0.3MPa, gas-liquid two-phase) after throttling, and then absorbs heat through the main cold box 6 (heat exchanger) to become C3 (temperature -50°C, gas), and then is pressurized by the compressor 7 to become out (temperature -30°C, gas), and then passes through the heat exchanger 5 to absorb the high-quality cold capacity (-145°C) of the cold storage medium P1 to become C1 (temperature -140°C, pressure 1MPa), completing the cryogenic refrigerant cycle.

[0049] During the refrigeration cycle, there is a law of conservation of energy. The load of the heat exchanger 5 = the power of the compressor 7 + the cold released by the deep cold refrigerant in the main cold box 6 (heat exchanger) (C2 to C3). Therefore, the significance of the refrigeration cycle is to improve the quality of the existing cold capacity (in the storage tank 19), but it will reduce the cold capacity. Although the cold capacity is reduced, the original cold capacity can be refrigerated and generated by air diversion, secondary pressurization and throttling (-145℃). In contrast, the cold capacity (-160℃) generated by the refrigeration cycle is irreplaceable.

[0050] The embodiment of the present disclosure provides a possible implementation method, in which the main cold box is provided with a diversion switch for controlling the flow rates of mainstream air and diversion air.

[0051] Specifically, when the mainstream air flow rate is large, the liquefaction rate of the mainstream air is low due to insufficient cooling (for example, the cooling capacity provided by the refrigeration cycle unit is limited). The flow rate of the diverted air can be increased. In this way, the diverted air is pressurized twice and then throttled, and the cooling capacity provided by the return flow to the main cold box 6 is increased. When the overall target compressed air volume remains unchanged, the cooling capacity provided is increased, thereby improving the liquefaction efficiency.

[0052] The embodiment of the present application solves the problem of how to control air diversion. When the system energy storage time increases, the flow rates of mainstream air and diverted air can be changed, thereby compensating for the problem caused by insufficient cooling capacity of the main cold box and improving the overall liquefaction rate of the system air.

[0053] It should also be noted that the illustrations provided in the following embodiments are only schematic illustrations of the basic concept of the embodiments of the present disclosure. The drawings only show components related to the embodiments of the present disclosure rather than being drawn according to the number, shape and size of components in actual implementation. In actual implementation, the type, quantity and proportion of each component may be changed arbitrarily, and the component layout may also be more complicated.

[0054] The following embodiments of the present disclosure are provided by specific specific examples to illustrate the embodiments of the present disclosure. Those skilled in the art can easily understand other advantages and effects of the present disclosure from the contents disclosed in this specification. Obviously, the described embodiments are only a part of the embodiments of the present disclosure, rather than all of the embodiments. The present disclosure can also be implemented or applied through other different specific embodiments, and the details in this specification can also be modified or changed in various ways based on different viewpoints and applications without departing from the spirit of the present disclosure. It should be noted that the following embodiments and features in the embodiments can be combined with each other without conflict. Based on the embodiments in the present disclosure, all other embodiments obtained by ordinary technicians in the field without making creative work are within the scope of protection of the present disclosure.

[0055] It should be noted that various aspects of the embodiments within the scope of the appended claims are described below. It should be apparent that the aspects described herein may be embodied in a wide variety of forms, and any specific structure and / or function described herein is merely illustrative. Based on the present disclosure, it should be understood by those skilled in the art that an aspect described herein may be implemented independently of any other aspect, and two or more of these aspects may be combined in various ways. For example, any number of aspects described herein may be used to implement the device and / or practice the method. In addition, other structures and / or functionalities other than one or more of the aspects described herein may be used to implement this device and / or practice this method.

[0056] The embodiments described above are part of the embodiments of the present disclosure, but not all of them. Based on the embodiments of the present disclosure, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the embodiments of the present disclosure.

[0057] In the description of the embodiments of the present disclosure, it should be noted that the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the drawings, and are only for the convenience of describing the embodiments of the present disclosure and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the embodiments of the present disclosure. In addition, the terms "first", "second", and "third" are used for descriptive purposes only and cannot be understood as indicating or implying relative importance.

[0058] In the description of the embodiments of the present disclosure, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be a direct connection, or it can be indirectly connected through an intermediate medium, or it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in the embodiments of the present disclosure can be understood according to specific circumstances.

[0059] The above are only specific implementations of the embodiments of the present disclosure, but the protection scope of the embodiments of the present disclosure is not limited thereto. Any changes or replacements that can be easily thought of by any technician familiar with the technical field within the technical scope disclosed in the embodiments of the present disclosure should be included in the protection scope of the embodiments of the present disclosure. Therefore, the protection scope of the embodiments of the present disclosure should be based on the protection scope of the claims.

Claims

1. A variable load liquid air compression energy storage system, comprising an air compression unit, a liquefaction unit, and an energy release unit, characterized in that: The liquefaction unit comprises: A main cold box with a flow-dividing function, a liquid expander, a fourth air compressor, a second throttle valve, a gas-liquid separator, and a liquid air storage tank; the main cold box is connected to the liquid expander, the gas-liquid separator, and the liquid air storage tank in sequence through pipelines; the main cold box is connected to the fourth air compressor, and a second flow-dividing valve is arranged between the main cold box and the fourth air compressor; The main cold box with a diversion function is used to separate the target air to be liquefied obtained by compression of the air compression unit into mainstream air and diversion air, and liquefy the target air to be liquefied when the target air to be liquefied passes through the main cold box; after the mainstream air enters the liquid expander, the liquid air is stored in a liquid air storage tank through a gas-liquid separator; the diversion air is pressurized by the fourth air compressor and diverted by the second diversion valve, and then returned to the main cold box for cooling.

2. The variable load liquid air compression energy storage system according to claim 1, characterized in that: The liquid expander is connected to the fourth air compressor via a connecting rod, so that the liquid expander can drive the fourth air compressor to pressurize the diverted air.

3. The variable load liquid air compression energy storage system according to claim 1, characterized in that: The fourth air compressor is a small air compressor.

4. The variable load liquid air compression energy storage system according to claim 1, characterized in that: The main cold box is connected to the fourth air compressor and the gas-liquid separator through a three-way pipe, and the second diverter valve is arranged between the three-way pipe connection and the fourth air compressor; the diverted air is pressurized by the fourth air compressor and diverted by the second diverter valve, and then mixed with the return air from the gas-liquid separator and returned to the main cold box for cooling.

5. The variable load liquid air compression energy storage system according to claim 1, characterized in that: The main cold box is provided with a diversion switch for controlling the flow rates of mainstream air and diversion air.

6. The variable load liquid air compression energy storage system according to any one of claims 1 to 5, characterized in that: The cold energy used by the main cold box to liquefy the target air to be liquefied comes from the circulating refrigeration unit: The circulating refrigeration unit is used to provide high-quality cold by using the cold stored in the cold storage subunit through the use of deep-cold refrigerant; the cold stored in the cold storage subunit comes from the cold brought by the temperature drop when the liquefied air stored in the liquefaction unit expands and releases energy during the energy release stage.

7. The variable load liquid air compression energy storage system according to any one of claims 1 to 5, characterized in that: The refrigeration cycle unit includes a cryogenic refrigerant, a condenser, a first throttle valve, and a third air compressor; The condenser, the first throttle valve, the main cold box of the liquefaction unit, and the third air compressor are connected in a loop in sequence; The deep cold refrigerant of the refrigeration cycle unit is condensed by the condenser using the cold stored in the cold storage subunit, and after passing through the first throttle valve, the temperature is reduced to a temperature lower than the temperature of the cold storage medium in the cold storage subunit, thereby providing high-quality cold for the main cold box of the liquefaction unit; the main cold box is used to liquefy the target air to be liquefied when it passes through; The third air compressor is used to pressurize the cryogenic refrigerant that has been vaporized after passing through the main cold box, and compress it to the condenser for recycling.

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