Liquefied air energy storage system

Abstract

The invention relates to the technical field of energy storage, and discloses a liquefied air energy storage system which comprises an air compression unit, an air liquefaction storage unit, a liquid air gasification unit and a cold storage unit. According to the liquefied air energy storage system provided by the scheme, air is stored in the form of liquid air, so that the problem of low energy storage density of compressed air can be solved. Moreover, according to the liquefied air energy storage system provided by the scheme, air is stored in the form of normal-pressure liquid air without depending on special geographical conditions and a large number of high-pressure containers and pipelines, and the cost is low.

Description

Technical Field

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

[0002] Since renewable energy generation such as wind and solar energy depends on natural resource conditions, it has the characteristics of intermittent generation and large fluctuations in power generation. In order to alleviate the impact of renewable energy generation grid connection and consumption on the power system and ensure the safe operation of the power system, it is usually necessary to build a supporting energy storage system that can achieve long-term energy storage and large-scale peak load regulation.

[0003] Among many energy storage technologies, compressed air energy storage has broad application prospects in the field of energy storage and peak regulation due to its advantages such as being green, safe, and long-life. The principle of compressed air energy storage is to compress the air to a high-pressure state and store it, and use the high-pressure air to generate electricity through a turbine when energy needs to be released. However, the energy storage density of compressed air energy storage is low, and the storage of compressed air depends on special geographical conditions, such as underground salt caverns, artificial chambers, etc., or relies on a large number of high-pressure containers and pipelines, resulting in high construction costs and equipment costs, and poor economic efficiency. Summary of the invention

[0004] The purpose of this application is to overcome the problems of low energy storage density and poor economy of energy storage systems in the prior art, and to provide a liquefied air energy storage system.

[0005] In an embodiment of the present application, the liquefied air energy storage system includes an air compression unit, an air liquefaction storage unit, a liquid air vaporization unit and a cold storage unit; the air compression unit is used to compress the introduced air; the air liquefaction storage unit includes a primary heat exchanger, a secondary heat exchanger and a liquid air storage tank; the liquid air vaporization unit includes a primary vaporizer, a secondary vaporizer and a first air turbine; the cold storage unit includes a first storage tank and a second storage tank for storing a first working fluid, and a third storage tank and a fourth storage tank for storing a second working fluid, the temperature of the first working fluid in the first storage tank is higher than the temperature of the first working fluid in the second storage tank, and the temperature of the second working fluid in the third storage tank is higher than the temperature of the second working fluid in the fourth storage tank; the compressed air outlet of the air compression unit is connected to the first inlet of the primary heat exchanger, the outlet of the second storage tank is connected to the second inlet of the primary heat exchanger, and the primary heat exchanger The first outlet of the first heat exchanger is communicated with the first inlet of the secondary heat exchanger, and the second outlet of the first heat exchanger is communicated with the inlet of the first storage tank; the outlet of the fourth storage tank is communicated with the second inlet of the secondary heat exchanger, the first outlet of the secondary heat exchanger is communicated with the inlet of the liquid air storage tank, and the second outlet of the secondary heat exchanger is communicated with the inlet of the third storage tank; the liquid outlet of the liquid air storage tank is communicated with the first inlet of the first vaporizer, the outlet of the third storage tank is communicated with the second inlet of the first vaporizer, the first outlet of the first vaporizer is communicated with the first inlet of the second vaporizer, and the second outlet of the first vaporizer is communicated with the inlet of the fourth tank; the outlet of the first storage tank is communicated with the second inlet of the second vaporizer, the first outlet of the second vaporizer is communicated with the inlet of the first air turbine, and the second outlet of the second vaporizer is communicated with the inlet of the second storage tank.

[0006] In an embodiment of the present application, the air compression unit includes an air filter, a first air compressor, a first interstage heat exchanger, an air purification device, a second air compressor and a second interstage heat exchanger; the inlet of the air filter is used to introduce air, the outlet of the air filter is connected to the inlet of the first air compressor, the outlet of the first air compressor is connected to the first inlet of the first interstage heat exchanger, the first outlet of the first interstage heat exchanger is connected to the first inlet of the air purification device, the outlet of the air purification device is connected to the inlet of the second air compressor, the outlet of the second air compressor is connected to the first inlet of the second interstage heat exchanger, and the first outlet of the second interstage heat exchanger is connected to the first inlet of the first heat exchanger.

[0007] In the embodiment of the present application, the first working fluid is methanol, and the second working fluid is propane.

[0008] In an embodiment of the present application, the air liquefaction storage unit also includes a first liquid turbine and a first throttle valve; the first outlet of the secondary heat exchanger is connected to the inlet of the first liquid turbine, the outlet of the first liquid turbine is connected to the inlet of the first throttle valve, and the outlet of the first throttle valve is connected to the inlet of the liquid air storage tank.

[0009] In an embodiment of the present application, the gas outlet of the liquid air storage tank is connected to the third inlet of the secondary heat exchanger, and the third outlet of the secondary heat exchanger is connected to the third inlet of the primary heat exchanger.

[0010] In an embodiment of the present application, the third outlet of the primary heat exchanger is connected to the second inlet of the air purification device.

[0011] In an embodiment of the present application, the liquid air gasification unit also includes a liquid air pump, a third interstage heat exchanger, a fourth interstage heat exchanger and a second air turbine; the liquid outlet of the liquid air storage tank is connected to the inlet of the liquid air pump, the outlet of the liquid air pump is connected to the first inlet of the first gasifier, the first outlet of the second gasifier is connected to the first inlet of the third interstage heat exchanger, the first outlet of the third interstage heat exchanger is connected to the inlet of the first air turbine, the outlet of the first air turbine is connected to the first inlet of the fourth interstage heat exchanger, and the first outlet of the fourth interstage heat exchanger is connected to the inlet of the second air turbine.

[0012] In an embodiment of the present application, the liquid air gasification unit also includes a fifth interstage heat exchanger, the first outlet of the second air turbine is connected to the inlet of the fifth interstage heat exchanger, and the first outlet of the fifth interstage heat exchanger is connected to the second inlet of the air purification device.

[0013] In an embodiment of the present application, the air liquefaction storage unit also includes a second throttle valve; the first outlet of the secondary heat exchanger is respectively connected to the inlet of the first liquid turbine and the inlet of the second throttle valve, and the outlet of the first liquid turbine and the outlet of the second throttle valve are both connected to the inlet of the first throttle valve.

[0014] In an embodiment of the present application, the air liquefaction storage unit also includes a gas turbine; the fourth outlet of the first-stage heat exchanger is connected to the inlet of the gas turbine, and the outlet of the second turbine is connected to the third inlet of the second-stage heat exchanger.

[0015] Through the above-mentioned liquefied air energy storage system, the liquefied air energy storage system includes an air compression unit, an air liquefaction storage unit, a liquid air vaporization unit and a cold storage unit; the air compression unit is used to compress the introduced air; the air liquefaction storage unit includes a primary heat exchanger, a secondary heat exchanger and a liquid air storage tank; the liquid air vaporization unit includes a primary vaporizer, a secondary vaporizer and a first air turbine; the cold storage unit includes a first storage tank and a second storage tank for storing a first working fluid, and includes a third storage tank and a fourth storage tank for storing a second working fluid, the temperature of the first working fluid in the first storage tank is higher than the temperature of the first working fluid in the second storage tank, and the temperature of the second working fluid in the third storage tank is higher than the temperature of the second working fluid in the fourth storage tank; the compressed air outlet of the air compression unit is connected to the first inlet of the primary heat exchanger, the outlet of the second storage tank is connected to the second inlet of the primary heat exchanger, and the first exchange The first outlet of the heat exchanger is connected to the first inlet of the secondary heat exchanger, and the second outlet of the primary heat exchanger is connected to the inlet of the first storage tank; the outlet of the fourth storage tank is connected to the second inlet of the secondary heat exchanger, the first outlet of the secondary heat exchanger is connected to the inlet of the liquid air storage tank, and the second outlet of the secondary heat exchanger is connected to the inlet of the third storage tank; the liquid outlet of the liquid air storage tank is connected to the first inlet of the primary vaporizer, the outlet of the third storage tank is connected to the second inlet of the primary vaporizer, the first outlet of the primary vaporizer is connected to the first inlet of the secondary vaporizer, and the second outlet of the primary vaporizer is connected to the inlet of the fourth storage tank; the outlet of the first storage tank is connected to the second inlet of the secondary vaporizer, the first outlet of the secondary vaporizer is connected to the inlet of the first air turbine, and the second outlet of the secondary vaporizer is connected to the inlet of the second storage tank. Since the liquefied air energy storage system provided in the embodiment of the present application stores air in the form of liquid air, it can solve the problem of low compressed air energy storage density. Furthermore, the liquefied air energy storage system provided in the embodiment of the present application stores air in the form of liquid air at normal pressure, does not rely on special geographical conditions and a large number of high-pressure containers and pipelines, and has a low cost.

[0016] Other features and advantages of the embodiments of the present application will be described in detail in the subsequent specific implementation section. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The accompanying drawings are used to provide a further understanding of the embodiments of the present application and constitute a part of the specification. Together with the following specific implementations, they are used to explain the embodiments of the present application, but do not constitute a limitation on the embodiments of the present application. In the accompanying drawings: Figure 1 A schematic diagram of the structure of a liquefied air energy storage system according to an embodiment of the present application is shown; Figure 2 A schematic diagram of the structure of another liquefied air energy storage system according to an embodiment of the present application is shown; Figure 3 A schematic structural diagram of another liquefied air energy storage system according to an embodiment of the present application is schematically shown.

[0018] Description of Reference Numerals 101—air filter; 102—first air compressor; 103—first interstage heat exchanger; 104—air purification device; 105—second air compressor; 106—second interstage heat exchanger; 201—first heat exchanger; 202—second heat exchanger; 203—liquid air storage tank; 204—first liquid turbine; 205—first throttle valve; 206—second throttle valve; 207—gas turbine; 301—first vaporizer; 302—second vaporizer; 303—first air turbine; 304—liquid air pump; 305—third interstage heat exchanger; 306—fourth interstage heat exchanger; 307—second air turbine; 308—fifth interstage heat exchanger; 401—first storage tank; 402—second storage tank; 403—third storage tank; 404—fourth storage tank. DETAILED DESCRIPTION

[0019] In order to make the purpose, technical solution and advantages of the embodiments of the present application clearer, the technical solution in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. It should be understood that the specific implementation methods described herein are only used to illustrate and explain the embodiments of the present application, and are not used to limit the embodiments of the present application. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0020] It should be noted that if the embodiments of the present application involve directional indications (such as up, down, left, right, front, back...), such directional indications are only used to explain the relative position relationship, movement status, etc. between the components under a certain specific posture (as shown in the accompanying drawings). If the specific posture changes, the directional indication will also change accordingly.

[0021] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present application, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such combination of technical solutions does not exist and is not within the scope of protection required by this application.

[0022] As described in the background technology, since renewable energy generation such as wind energy and solar energy depends on natural resource conditions, it has the characteristics of intermittent power generation and large fluctuations in power generation. In order to alleviate the impact of renewable energy generation grid connection and consumption on the power system and ensure the safe operation of the power system, it is usually necessary to build a supporting energy storage system that can achieve long-term energy storage and large-scale peak regulation. Among many energy storage technologies, compressed air energy storage has broad application prospects in the field of energy storage and peak regulation due to its advantages such as green, safe, and long life. The principle of compressed air energy storage is: compress the air to a high-pressure state and store it, and use the high-pressure air to generate electricity through a turbine when energy release is required. However, the energy storage density of compressed air energy storage is low, and the storage of compressed air depends on special geographical conditions or a large number of high-pressure containers and pipelines. For example, 1) Using underground salt caverns to store compressed air requires that there are salt cavern resources that meet the requirements around the project, which severely limits the project site selection; 2) Using artificial chambers to store compressed air requires manual excavation in underground rock formations that reach the hardness of granite, which severely limits the project site selection and has high construction costs; 3) Using high-pressure gas pipelines and storage tanks to store compressed air makes the equipment cost of the energy storage system higher and occupies a larger area.

[0023] In view of this, in one embodiment of the present application, a liquefied air energy storage system is provided, such as Figure 1As shown, the liquefied air energy storage system may include an air compression unit, an air liquefaction storage unit, a liquid air gasification unit and a cold storage unit; the air compression unit is used to compress the introduced air; the air liquefaction storage unit includes a primary heat exchanger 201, a secondary heat exchanger 202 and a liquid air storage tank 203; the liquid air gasification unit includes a primary gasifier 301, a secondary gasifier 302 and a first air turbine 303; the cold storage unit includes a first storage tank 401 and a second storage tank 402 for storing a first working fluid, and The invention comprises a third storage tank 403 and a fourth storage tank 404 for storing a second working fluid, wherein the temperature of the first working fluid in the first storage tank 401 is higher than the temperature of the first working fluid in the second storage tank 402, and the temperature of the second working fluid in the third storage tank 403 is higher than the temperature of the second working fluid in the fourth storage tank 404; the compressed air outlet of the air compression unit is connected to the first inlet of the first heat exchanger 201, the outlet of the second storage tank 402 is connected to the second inlet of the first heat exchanger 201, and the first outlet of the first heat exchanger 201 is connected to the second The first inlet of the heat exchanger 202 is communicated, and the second outlet of the first heat exchanger 201 is communicated with the inlet of the first storage tank 401; the outlet of the fourth storage tank 404 is communicated with the second inlet of the second heat exchanger 202, the first outlet of the second heat exchanger 202 is communicated with the inlet of the liquid air storage tank 203, and the second outlet of the second heat exchanger 202 is communicated with the inlet of the third storage tank 403; the liquid outlet of the liquid air storage tank 203 is communicated with the first inlet of the first vaporizer 301, and the third storage tank 40 3 is connected to the second inlet of the first-level gasifier 301, the first outlet of the first-level gasifier 301 is connected to the first inlet of the second-level gasifier 302, and the second outlet of the first-level gasifier 301 is connected to the inlet of the fourth storage tank 404; the outlet of the first storage tank 401 is connected to the second inlet of the second-level gasifier 302, the first outlet of the second-level gasifier 302 is connected to the inlet of the first air turbine 303, and the second outlet of the second-level gasifier 302 is connected to the inlet of the second storage tank 402.

[0024] In an embodiment of the present application, the air compression unit can be used to perform preliminary compression and cooling of air. In one embodiment, the air compression unit may include an air filter 101, a first air compressor 102, a first interstage heat exchanger 103, an air purification device 104, a second air compressor 105, and a second interstage heat exchanger 106; the inlet of the air filter 101 is used to introduce air, the outlet of the air filter 101 is communicated with the inlet of the first air compressor 102, the outlet of the first air compressor 102 is communicated with the first inlet of the first interstage heat exchanger 103, the first outlet of the first interstage heat exchanger 103 is communicated with the first inlet of the air purification device 104, the outlet of the air purification device 104 is communicated with the inlet of the second air compressor 105, the outlet of the second air compressor 105 is communicated with the first inlet of the second interstage heat exchanger 106, and the first outlet of the second interstage heat exchanger 106 is communicated with the first inlet of the first heat exchanger 201.

[0025] The air filter 101 can be used to remove larger particles in the air, thereby reducing the dust content in the compressed air and preventing the particles from causing wear on the rotating parts of the compressor.

[0026] The first air compressor 102 and the second air compressor 105 can be used to compress the air step by step to compress the air to a high pressure state. In specific implementation, the first air compressor 102 and the second air compressor 105 can be driven by motors, and the first air compressor 102 and the second air compressor 105 can be axial flow compressors or centrifugal compressors.

[0027] In actual applications, the pressure and temperature of air will increase after being compressed by a compressor. In order to ensure the compression efficiency of the next air compressor and the liquefaction efficiency of the high-pressure air output by the air compression unit, a first inter-stage heat exchanger 103 is arranged after the first air compressor 102, and a second inter-stage heat exchanger 106 is arranged after the second air compressor 105, so as to cool the compressed high-temperature and high-pressure air.

[0028] In a specific implementation, the second inlet of the first interstage heat exchanger 103 and the second inlet of the second interstage heat exchanger 106 can be used to introduce a cold source. The cold source of the first interstage heat exchanger 103 and the second interstage heat exchanger 106 can be a cold source outside the system or a circulating cold source inside the system. In the case where the cold source of the first interstage heat exchanger 103 and the second interstage heat exchanger 106 is a cold source outside the system, when there is a medium that needs to be heated outside the system, the medium can be used as a cold source and input into the first interstage heat exchanger 103 and the second interstage heat exchanger 106, and the compression heat of the air can be used to heat the medium. In the case where the cold source of the first interstage heat exchanger 103 and the second interstage heat exchanger 106 is a circulating cold source inside the system, after heat exchange, the internal circulating cold source can absorb the air compression heat and store it, and is used to provide heat for the third interstage heat exchanger 305 and the fourth interstage heat exchanger 306 in the subsequent liquid air gasification unit.

[0029] The air purification device 104 can be used to remove impurities such as water, CO2, heavy metals, etc. in the compressed air by using the pressure swing adsorption principle, so as to achieve the purpose of drying and purifying the air.

[0030] When the air flow rate that the air compression unit needs to handle is large, which exceeds the processing range of a single air compressor or exceeds the selection range of the compressor motor, the above-mentioned route (air filter 101 - first air compressor 102 - first interstage heat exchanger 103 - air purification device 104 - second air compressor 105 - second interstage heat exchanger 106) can be referred to, and multiple parallel routes can be set up, and the first outlet of each second interstage heat exchanger 106 is connected to the first inlet of the first heat exchanger 201.

[0031] In the embodiment of the present application, the air liquefaction storage unit can be used to liquefy and store the air output by the air compression unit.

[0032] Among them, the primary heat exchanger 201 and the secondary heat exchanger 202 can be used to cool down the high-temperature and high-pressure air output by the air compression unit in sequence. The cold source of the primary heat exchanger 201 is the first working fluid with a lower temperature in the second storage tank 402, and the cold source of the secondary heat exchanger 202 is the second working fluid with a lower temperature in the fourth storage tank 404. That is, in the primary heat exchanger 201, the air exchanges heat with the first working fluid with a lower temperature, and the air with a lower temperature after the heat exchange is further transported to the secondary heat exchanger 202, and the first working fluid with a higher temperature after the heat exchange is transported to the first storage tank 401 for storage. In the secondary heat exchanger 202, the air exchanges heat with the second working fluid with a lower temperature, and the air with a lower temperature after the heat exchange is further transported to the liquid air storage tank 203, and the second working fluid with a higher temperature after the heat exchange is transported to the third storage tank 403 for storage.

[0033] In order to introduce the first working medium from the second storage tank 402 as the cold source of the primary heat exchanger 201 to realize the above heat exchange process, a pumping device M may be provided on the pipeline connecting the outlet of the second storage tank 402 and the second inlet of the primary heat exchanger 201. Similarly, in order to introduce the second working medium from the fourth storage tank 404 as the cold source of the secondary heat exchanger 202 to realize the above heat exchange process, a pumping device M may be provided on the pipeline connecting the outlet of the fourth storage tank 404 and the second inlet of the secondary heat exchanger 202.

[0034] In order to further improve the cooling effect of the first working fluid and the second working fluid on the air and improve the energy storage effect of the first working fluid and the second working fluid, the first working fluid can be methanol and the second working fluid can be propane. More specifically, the temperature of the methanol in the second storage tank 402 can be -80°C to -100°C, preferably about -90°C; the temperature of the propane in the fourth storage tank 404 can be -180°C to -160°C, preferably about -170°C.

[0035] In actual application, the temperature of the air input to the primary heat exchanger 201 is about 35° C. After being cooled by the methanol having the above temperature, the temperature of the air is reduced to about -90° C., and the temperature of the methanol is increased to about 30° C. In the secondary heat exchanger 202, the air is further cooled by the propane having the above temperature, and the temperature of the air is reduced to about -170° C., and the temperature of the propane is increased to about -90° C.

[0036] Through the above process, methanol and propane complete the deep cooling of the air, reducing the temperature of the high-pressure air to about -170°C, and most of the air can be converted into liquid air and liquefied.

[0037] In order to further reduce the temperature and pressure of the liquid air, the air liquefaction storage unit may also include a first liquid turbine 204 and a first throttle valve 205; the first outlet of the secondary heat exchanger 202 is connected to the inlet of the first liquid turbine 204, the outlet of the first liquid turbine 204 is connected to the inlet of the first throttle valve 205, and the outlet of the first throttle valve 205 is connected to the inlet of the liquid air storage tank 203.

[0038] In the first liquid turbine 204, the liquid air expands and performs work, and the temperature and pressure of the liquid air are further reduced, and then the air is further cooled and depressurized through the first throttle valve 205, so that the air can be stored in the liquid air storage tank 203 in the form of normal pressure liquid. The liquid air storage tank 203 can be a normal pressure storage tank, which stores normal pressure liquid air at a temperature of about -190°C.

[0039] In practical applications, since there is some flash air in the liquid air entering the liquid air storage tank 203, the temperature is about -190°C and has a large cooling capacity. In order to utilize this cooling capacity, in one embodiment, the gas outlet of the liquid air storage tank 203 is connected to the third inlet of the secondary heat exchanger 202, and the third outlet of the secondary heat exchanger 202 is connected to the third inlet of the primary heat exchanger 201.

[0040] Through the above arrangement, the flash air with a relatively low temperature can be input into the secondary heat exchanger 202 and the primary heat exchanger 201 to participate in the heat exchange process therein. Thus, while being able to utilize the coldness in the flash air, the compressed air to be cooled in the secondary heat exchanger 202 and the primary heat exchanger 201 can also be cooled, thereby improving the cooling effect of the compressed air to be cooled in the secondary heat exchanger 202 and the primary heat exchanger 201.

[0041] Considering that the flash air still has a certain amount of cold after heat exchange in the primary heat exchanger 201 , in order to further utilize the cold, in one embodiment, the third outlet of the primary heat exchanger 201 is connected to the second inlet of the air purification device 104 .

[0042] Through the above arrangement, the flash air with a certain amount of cooling can be used as cold blowing air for the air purification adsorption layer in the air purification device 104 to cool the adsorption bed.

[0043] In the embodiment of the present application, the liquid air gasification unit can be used to gasify liquid air. In practical applications, in order to obtain high-pressure gasified air, the liquid air gasification unit can also include a liquid air pump 304, the liquid outlet of the liquid air storage tank 203 is connected to the inlet of the liquid air pump 304, and the outlet of the liquid air pump 304 is connected to the first inlet of the primary gasifier 301.

[0044] The liquid air pump 304 may be used to pressurize the normal-pressure liquid air output from the liquid air storage tank 203 to a high-pressure state.

[0045] The primary vaporizer 301 and the secondary vaporizer 302 can be used to heat and vaporize the high-pressure liquid air output by the liquid air pump 304 in sequence, and can be specifically vaporized by isobaric heating to obtain high-pressure normal-temperature gaseous air. The heat source of the primary vaporizer 301 is the second working fluid with a higher temperature stored in the third storage tank 403, and the heat source of the secondary vaporizer 302 is the first working fluid with a higher temperature stored in the first storage tank 401. That is, in the primary vaporizer 301, the liquid air is heat exchanged with the second working fluid with a higher temperature, and the air with a higher temperature after the heat exchange is further transported to the secondary vaporizer 302, and the first working fluid with a lower temperature after the heat exchange is transported to the fourth storage tank 404 for storage. In the secondary vaporizer 302, the air with a higher temperature is further heat exchanged with the first working fluid with a higher temperature, and the air with a higher temperature after the heat exchange is further transported to the first air turbine 303, and the first working fluid with a lower temperature after the heat exchange is transported to the second storage tank 402 for storage.

[0046] In order to introduce the second working medium from the third storage tank 403 as the heat source of the primary gasifier 301 to achieve the above heat exchange process, a pumping device M may be provided on the pipeline connecting the outlet of the third storage tank 403 and the second inlet of the primary gasifier 301. Similarly, in order to introduce the first working medium from the first storage tank 401 as the heat source of the secondary gasifier 302 to achieve the above heat exchange process, a pumping device M may be provided on the pipeline connecting the outlet of the first storage tank 401 and the second inlet of the secondary gasifier 302.

[0047] In actual application, after heat exchange in the first-stage vaporizer 301, the normal-pressure liquid air at about -190°C output from the liquid air storage tank 203 is heated to about -120°C, and the propane temperature is reduced from about -90°C to about -170°C. After further heat exchange in the second-stage vaporizer 302, the air at about -120°C is heated to room temperature, and the methanol temperature is reduced from about 30°C to about -90°C.

[0048] Through the above process, methanol and propane complete the process of gasifying liquid air and heating it to room temperature, and methanol and propane also complete the process of cooling and storing cold.

[0049] In order to further improve the working capacity of the air output by the secondary vaporizer 302, the liquid air vaporization unit may further include a third interstage heat exchanger 305, a fourth interstage heat exchanger 306 and a second air turbine 307, the first outlet of the secondary vaporizer 302 is connected to the first inlet of the third interstage heat exchanger 305, the first outlet of the third interstage heat exchanger 305 is connected to the inlet of the first air turbine 303, the outlet of the first air turbine 303 is connected to the first inlet of the fourth interstage heat exchanger 306, and the first outlet of the fourth interstage heat exchanger 306 is connected to the inlet of the second air turbine 307.

[0050] The third interstage heat exchanger 305 can be used to further heat the air output from the secondary gasifier 302. The heat source of the third interstage heat exchanger 305 can be a system external heat source, and the external heat source is used to heat the high-pressure air to a temperature suitable for the turbine of the first air turbine 303. The heat source of the third interstage heat exchanger 305 can also be a system internal circulation heat source, such as introducing a heat source from the second outlet of the first interstage heat exchanger 103 and / or the second inlet of the second interstage heat exchanger 106.

[0051] The first air turbine 303 may specifically be a high-pressure cylinder of the air turbine, and the second air turbine 307 may specifically be a medium-pressure cylinder or a low-pressure cylinder of the air turbine.

[0052] In practical applications, after the high-pressure normal-temperature gaseous air enters the third interstage heat exchanger 305, the temperature can be raised to above 170°C. After entering the high-pressure cylinder turbine to perform work, the exhaust temperature is reduced to 20°C~30°C. The fourth interstage heat exchanger 306 can be used to further heat the exhaust gas of the high-pressure cylinder so that it can continue to enter the medium-pressure cylinder or the low-pressure cylinder to perform work. Similarly, the heat source of the fourth interstage heat exchanger 306 can be a system external heat source, and the external heat source is used to heat the high-pressure air to a temperature suitable for the second air turbine 307 turbine. The heat source of the fourth interstage heat exchanger 306 can also be a system internal circulation heat source, such as introducing a heat source from the second outlet of the first interstage heat exchanger 103 and / or the second inlet of the second interstage heat exchanger 106.

[0053] In specific implementation, more stages of air turbines can be set according to the system energy storage power generation demand, and matching inter-stage heat exchangers can be set according to the above scheme to ensure the turbine temperature.

[0054] Furthermore, in order to be able to desorb the adsorption bed in the air purification device 104, in one embodiment, the liquid air gasification unit may also include a fifth interstage heat exchanger 308, the first outlet of the second air turbine 307 is connected to the inlet of the fifth interstage heat exchanger 308, and the first outlet of the fifth interstage heat exchanger 308 is connected to the second inlet of the air purification device 104.

[0055] The exhaust gas of the second air turbine 307 can be divided into two parts, one part is input into the fifth inter-stage heat exchanger 308, and the other part is directly discharged into the atmosphere.

[0056] The fifth interstage heat exchanger 308 can be used to heat the input exhaust gas. Similarly, the heat source of the fifth interstage heat exchanger 308 can be a system external heat source. The heat source of the fifth interstage heat exchanger 308 can also be a system internal circulation heat source, such as introducing a heat source from the second outlet of the first interstage heat exchanger 103 and / or the second inlet of the second interstage heat exchanger 106.

[0057] In practical applications, after heat exchange in the fifth inter-stage heat exchanger 308, the air can be heated to about 170°C, and the high-temperature air can be input into the air purification device 104 as desorption regeneration gas for the adsorption bed.

[0058] To ensure the smooth operation of the system, in the specific design, the air flow rate that the air compression unit can handle is greater than the air flow rate that the air liquefaction storage unit and the liquid air gasification unit can handle.

[0059] It can be understood that the liquefied air energy storage system provided in the embodiment of the present application includes two stages: energy storage and energy release, which are as follows: during energy storage, the first working fluid with a lower temperature is input from the second storage tank 402 into the primary heat exchanger 201, and the air input into the primary heat exchanger 201 is cooled, and the temperature of the first working fluid increases and enters the first storage tank 401 for storage. The second working fluid with a lower temperature is input from the fourth storage tank 404 into the secondary heat exchanger 202, and the air input from the primary heat exchanger 201 into the secondary heat exchanger 202 is further cooled, and the temperature of the second working fluid increases and enters the third storage tank 403 for storage. Through this process, the first working fluid and the second working fluid complete the deep cooling of the air, and most of the air is converted into liquid air, and the first working fluid and the second working fluid also complete the process of heating and heat storage.

[0060] When releasing energy, the second working fluid with a higher temperature is input from the third storage tank 403 into the primary vaporizer 301, and the air input into the primary vaporizer 301 is heated. The temperature of the second working fluid is reduced and stored in the fourth storage tank 404. The first working fluid with a higher temperature is input from the first storage tank 101 into the secondary vaporizer 302, and the air input from the primary vaporizer 301 into the secondary vaporizer 302 is further heated. The temperature of the first working fluid is reduced and stored in the second storage tank 402. Through this process, the liquid air completes the vaporization and temperature increase process, and the first working fluid and the second working fluid also complete the process of cooling and storing cold.

[0061] It can be understood that the liquefied air energy storage system provided in the embodiment of the present application includes an air compression unit, an air liquefaction storage unit, a liquid air gasification unit and a cold storage unit; the air compression unit is used to compress the introduced air; the air liquefaction storage unit includes a primary heat exchanger 201, a secondary heat exchanger 202 and a liquid air storage tank 203; the liquid air gasification unit includes a primary gasifier 301, a secondary gasifier 302 and a first air turbine 303; the cold storage unit includes a first storage tank 401 for storing a first working fluid and The second storage tank 402, and the third storage tank 403 and the fourth storage tank 404 for storing the second working fluid, the temperature of the first working fluid in the first storage tank 401 is higher than the temperature of the first working fluid in the second storage tank 402, the temperature of the second working fluid in the third storage tank 403 is higher than the temperature of the second working fluid in the fourth storage tank 404; the compressed air outlet of the air compression unit is connected to the first inlet of the primary heat exchanger 201, the outlet of the second storage tank 402 is connected to the second inlet of the primary heat exchanger 201, and the first The outlet of the second heat exchanger 202 is communicated with the first inlet of the second heat exchanger 202, the second outlet of the first heat exchanger 201 is communicated with the inlet of the first storage tank 401; the outlet of the fourth storage tank 404 is communicated with the second inlet of the second heat exchanger 202, the first outlet of the second heat exchanger 202 is communicated with the inlet of the liquid air storage tank 203, the second outlet of the second heat exchanger 202 is communicated with the inlet of the third storage tank 403; the liquid outlet of the liquid air storage tank 203 is communicated with the first inlet of the first vaporizer 301, the third storage tank The outlet of tank 403 is connected to the second inlet of the primary vaporizer 301, the first outlet of the primary vaporizer 301 is connected to the first inlet of the secondary vaporizer 302, and the second outlet of the primary vaporizer 301 is connected to the inlet of the fourth storage tank 404; the outlet of the first storage tank 401 is connected to the second inlet of the secondary vaporizer 302, the first outlet of the secondary vaporizer 302 is connected to the inlet of the first air turbine 303, and the second outlet of the secondary vaporizer 302 is connected to the inlet of the second storage tank 402. Since the liquefied air energy storage system provided in the embodiment of the present application stores air in the form of liquid air, it can solve the problem of low compressed air energy storage density, and the energy storage density (measured in power generation per unit gas storage volume) is 15-20 times that of compressed air energy storage. In addition, the liquefied air energy storage system provided in the embodiment of the present application stores air in the form of normal pressure liquid air, does not rely on special geographical conditions and a large number of high-pressure containers and pipelines, and has low cost.

[0062] Based on the liquefied air energy storage system provided in the embodiment of the present application, the air can be compressed and purified by utilizing valley electricity or abandoned electricity from new energy sources, and then the compressed air can be liquefied and stored at normal pressure; when the power demand of the power grid is at a peak, the liquefied air can be gasified and then passed through an air turbine to generate electricity to meet the power demand of the power grid.

[0063] According to calculations, the liquefied air energy storage system provided in the embodiment of the present application can achieve large-scale and long-term energy storage, with an energy storage time of 1-24 hours and an energy release power of up to 100 MW, so as to provide distribution storage for large-scale grid connection of new energy and meet the needs of peak load shaving and valley filling on the grid side and the user side. In addition, the liquefied air energy storage system provided in the embodiment of the present application is also characterized by low carbon, clean, safe, stable and long life.

[0064] In addition, cascade cold storage can be achieved through methanol and propane. Both working fluids are in liquid phase and there is no phase change, which can reduce the difficulty of cold storage and the complexity of the system.

[0065] In practical applications, such as Figure 2 As shown, the air liquefaction storage unit may further include a second throttle valve 206; the first outlet of the secondary heat exchanger 202 is respectively connected to the inlet of the first liquid turbine 204 and the inlet of the second throttle valve 206, and the outlet of the first liquid turbine 204 and the outlet of the second throttle valve 206 are both connected to the inlet of the first throttle valve 205, and then the subsequent process continues.

[0066] When the system is in the process of starting up, the air outputted by the secondary heat exchanger 202 is gas-liquid two-phase, and can directly enter the second throttle valve 206 (without entering the first liquid turbine 204) and the first throttle valve 205 for throttling and cooling. During the starting process, the liquid air generated after passing through the secondary heat exchanger 202 is less, gas-liquid two-phase, and cannot reach the state of starting the first liquid turbine 204. Therefore, it is directly throttled through the second throttle valve 206 and the first throttle valve 205, and further liquefied and stored in the liquid air storage tank 203, thereby improving the liquefaction rate of the air during the starting process.

[0067] In practical applications, such as Figure 3 As shown, the air liquefaction storage unit may further include a gas turbine 207 ; the fourth outlet of the first-stage heat exchanger 201 is connected to the inlet of the gas turbine 207 , and the outlet of the second turbine 207 is connected to the third inlet of the second-stage heat exchanger 202 .

[0068] The air cooled by the first working medium in the primary heat exchanger 201 can be separated into one path (the volume flow rate accounts for about 5% to 10%) and output from the fourth outlet and enter the gas turbine 207. After being expanded to a normal pressure state by the gas turbine 207, the air temperature is reduced to -190°C. This part of the normal pressure low temperature air and the flash air output from the liquid air storage tank 203 are used as a supplementary cold source for the primary heat exchanger 201 and the secondary heat exchanger 202, which can supplement the cold capacity of the system, increase the outlet pressure of the liquid air pump 304, and improve the system efficiency.

[0069] It should also be noted that the terms "include", "comprises" or any other variations thereof are intended to cover non-exclusive inclusion, so that a process, method, commodity or device including a series of elements includes not only those elements, but also other elements not explicitly listed, or also includes elements inherent to such process, method, commodity or device. In the absence of more restrictions, the elements defined by the sentence "comprises a ..." do not exclude the existence of other identical elements in the process, method, commodity or device including the elements.

[0070] The above are only embodiments of the present application and are not intended to limit the present application. For those skilled in the art, the present application may have various changes and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application should be included within the scope of the claims of the present application.

Claims

1. A liquefied air energy storage system, characterized in that: The liquefied air energy storage system includes an air compression unit, an air liquefaction storage unit, a liquid air gasification unit and a cold storage unit; the air compression unit is used to compress the introduced air; the air liquefaction storage unit includes a primary heat exchanger, a secondary heat exchanger and a liquid air storage tank; The liquid air gasification unit includes a primary gasifier, a secondary gasifier and a first air turbine; the cold storage unit includes a first storage tank and a second storage tank for storing a first working fluid, and includes a third storage tank and a fourth storage tank for storing a second working fluid, the temperature of the first working fluid in the first storage tank is higher than the temperature of the first working fluid in the second storage tank, and the temperature of the second working fluid in the third storage tank is higher than the temperature of the second working fluid in the fourth storage tank; the compressed air outlet of the air compression unit is connected to the first inlet of the primary heat exchanger, the outlet of the second storage tank is connected to the second inlet of the primary heat exchanger, the first outlet of the primary heat exchanger is connected to the first inlet of the secondary heat exchanger, and the second outlet of the primary heat exchanger is connected to the inlet of the first storage tank; the fourth storage tank The outlet of the tank is communicated with the second inlet of the secondary heat exchanger, the first outlet of the secondary heat exchanger is communicated with the inlet of the liquid air storage tank, and the second outlet of the secondary heat exchanger is communicated with the inlet of the third storage tank; the liquid outlet of the liquid air storage tank is communicated with the first inlet of the primary vaporizer, the outlet of the third storage tank is communicated with the second inlet of the primary vaporizer, the first outlet of the primary vaporizer is communicated with the first inlet of the secondary vaporizer, and the second outlet of the primary vaporizer is communicated with the inlet of the fourth storage tank; the outlet of the first storage tank is communicated with the second inlet of the secondary vaporizer, the first outlet of the secondary vaporizer is communicated with the inlet of the first air turbine, and the second outlet of the secondary vaporizer is communicated with the inlet of the second storage tank.

2. The liquefied air energy storage system according to claim 1, characterized in that: The air compression unit includes an air filter, a first air compressor, a first interstage heat exchanger, an air purification device, a second air compressor and a second interstage heat exchanger; the inlet of the air filter is used to introduce air, the outlet of the air filter is connected to the inlet of the first air compressor, the outlet of the first air compressor is connected to the first inlet of the first interstage heat exchanger, the first outlet of the first interstage heat exchanger is connected to the first inlet of the air purification device, the outlet of the air purification device is connected to the inlet of the second air compressor, the outlet of the second air compressor is connected to the first inlet of the second interstage heat exchanger, and the first outlet of the second interstage heat exchanger is connected to the first inlet of the first heat exchanger.

3. The liquefied air energy storage system according to claim 1, characterized in that: The first working fluid is methanol, and the second working fluid is propane.

4. The liquefied air energy storage system according to claim 1, characterized in that: The air liquefaction storage unit also includes a first liquid turbine and a first throttle valve; the first outlet of the secondary heat exchanger is connected to the inlet of the first liquid turbine, the outlet of the first liquid turbine is connected to the inlet of the first throttle valve, and the outlet of the first throttle valve is connected to the inlet of the liquid air storage tank.

5. The liquefied air energy storage system according to claim 2, characterized in that: The gas outlet of the liquid air storage tank is communicated with the third inlet of the secondary heat exchanger, and the third outlet of the secondary heat exchanger is communicated with the third inlet of the primary heat exchanger.

6. The liquefied air energy storage system according to claim 5, characterized in that: The third outlet of the primary heat exchanger is in communication with the second inlet of the air purification device.

7. The liquefied air energy storage system according to claim 2, characterized in that: The liquid air gasification unit also includes a liquid air pump, a third interstage heat exchanger, a fourth interstage heat exchanger and a second air turbine; the liquid outlet of the liquid air storage tank is connected to the inlet of the liquid air pump, the outlet of the liquid air pump is connected to the first inlet of the first gasifier, the first outlet of the second gasifier is connected to the first inlet of the third interstage heat exchanger, the first outlet of the third interstage heat exchanger is connected to the inlet of the first air turbine, the outlet of the first air turbine is connected to the first inlet of the fourth interstage heat exchanger, and the first outlet of the fourth interstage heat exchanger is connected to the inlet of the second air turbine.

8. The liquefied air energy storage system according to claim 7, characterized in that: The liquid air gasification unit further comprises a fifth inter-stage heat exchanger, the first outlet of the second air turbine is communicated with the inlet of the fifth inter-stage heat exchanger, and the first outlet of the fifth inter-stage heat exchanger is communicated with the second inlet of the air purification device.

9. The liquefied air energy storage system according to claim 4, characterized in that: The air liquefaction storage unit also includes a second throttle valve; the first outlet of the secondary heat exchanger is respectively connected to the inlet of the first liquid turbine and the inlet of the second throttle valve, and the outlet of the first liquid turbine and the outlet of the second throttle valve are both connected to the inlet of the first throttle valve.

10. The liquefied air energy storage system according to claim 6, characterized in that: The air liquefaction storage unit also includes a gas turbine; the fourth outlet of the first-stage heat exchanger is connected to the inlet of the gas turbine, and the outlet of the second turbine is connected to the third inlet of the second-stage heat exchanger.

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