Low-temperature medium energy storage system and energy storage method

Abstract

This application proposes a cryogenic medium energy storage system and method. The main energy storage containers are ambient temperature tanks and cryogenic tanks for storing liquid carbon dioxide. The system volume is reduced by more than 90% compared to gas storage facilities, and it can be entirely based on ground-mounted pressure vessels, offering flexible site selection and a small footprint. Furthermore, all equipment in this application can be integrated using existing mature products and technologies, eliminating the need for new equipment development, which helps reduce investment costs and accelerate the large-scale construction of energy storage facilities. The media used in this application are all common natural media used in the industrial field, offering advantages such as safety, environmental friendliness, and low cost. Simultaneously, the process flow is simple, reliable, and has low operating and maintenance costs, facilitating unattended operation.

Description

Technical Field

[0001] This application relates to the field of energy storage technology, and in particular to a cryogenic medium energy storage system and energy storage method. Background Technology

[0002] Compressed gas energy storage technology is a type of power storage system capable of storing large-capacity, long-term electrical energy. It stores excess electricity by compressing atmospheric pressure gas to high pressure using a compressor. When electricity is needed, the high-pressure gas is released and expands to generate electricity. Compressed gas energy storage mainly includes compressed air energy storage and compressed carbon dioxide energy storage.

[0003] Compressed gas energy storage devices require large-capacity gas storage tanks to store the gas. Compressed air energy storage uses high-pressure gas storage, and the storage tanks often need to be underground caverns to meet the volume and pressure requirements. Compressed carbon dioxide energy storage uses atmospheric pressure gas storage, and the storage tanks are extremely large, requiring a correspondingly large land area. These issues limit the large-scale promotion of compressed gas energy storage. The "System and Method for Integrated Carbon Dioxide Sequestration and Energy Storage Power Generation" (ZL 2023 1 0668425.9) uses high-pressure and low-pressure storage tanks to store liquid carbon dioxide. During energy storage, the liquid carbon dioxide is transferred from the high-pressure storage tank to the low-pressure storage tank, and during energy release, the liquid carbon dioxide is transferred from the low-pressure storage tank to the high-pressure storage tank. However, the working fluid depressurization and cooling components during energy storage cannot store heat, and the working fluid pressurization and heating components during energy release power generation need to utilize external waste heat to generate electricity using the working fluid expander, which limits its application scenarios. Summary of the Invention

[0004] This application aims to at least partially address one of the technical problems in the related art.

[0005] Therefore, the purpose of this application is to propose a cryogenic medium energy storage system and energy storage method, wherein carbon dioxide is used as the energy storage medium. Electrical energy is converted into thermal energy and pressure energy through carbon dioxide compression, and thermal energy and pressure energy are converted into electrical energy again through carbon dioxide expansion. Gaseous carbon dioxide can be phase-changed into liquid for storage, and thermal energy can be stored through a thermal storage medium. It does not require a large-volume gas storage facility, thus eliminating the need for underground space resources or large land use requirements.

[0006] To achieve the above objectives, this application proposes a cryogenic dielectric energy storage system, comprising:

[0007] A first energy storage subsystem includes a cryogenic tank and an ambient temperature tank, which are interconnected and used to store liquid carbon dioxide at different temperatures, and a first turbine assembly and a cryogenic cold storage body, respectively connected to the cryogenic tank and the ambient temperature tank. The first turbine assembly compresses carbon dioxide and generates electricity using carbon dioxide under different operating conditions. The cryogenic cold storage body vaporizes liquid carbon dioxide or liquefies gaseous carbon dioxide under constant pressure under different operating conditions of the first turbine assembly. The cryogenic tank is divided into an air chamber and a liquid chamber by a flexible diaphragm. The air chamber and the liquid chamber have equal pressure, and the volume of the air chamber is adjusted by the expansion and contraction of the flexible diaphragm.

[0008] The second energy storage subsystem, connected to the air cavity, includes a chiller, a second turbine assembly, and a heat exchange assembly. The second turbine assembly compresses air and generates electricity using air expansion under different operating conditions. The heat exchange assembly releases or stores heat / cold energy into the compressed air in the second turbine assembly under different operating conditions. The chiller is connected to the second turbine assembly and is used to compress air and cool the air input to the cryogenic tank.

[0009] In some embodiments, the first energy storage subsystem further includes a first heat exchange and heat storage component and a heat recovery component respectively connected to the first turbine component. The first heat exchange and heat storage component is used to release or store heat to the gas carbon dioxide in the first turbine component under different operating conditions of the first turbine component. The heat recovery component is used to increase the inlet temperature of the first turbine component under different operating conditions of the first turbine component.

[0010] In some embodiments, the first energy storage subsystem further includes a gas-liquid phase change component connected to the first turbine component, which, under different operating conditions of the first turbine component, liquefies gaseous carbon dioxide or vaporizes liquid carbon dioxide while maintaining a constant pressure of carbon dioxide; the gas-liquid phase change component is connected to the ambient temperature tank, and simultaneously inputs liquid or gaseous carbon dioxide into the ambient temperature tank under different operating conditions of the first turbine component, so as to maintain the stability of the gas pressure in the ambient temperature tank.

[0011] In some embodiments, the heat exchange assembly includes a second heat exchange and heat storage assembly and a cold exchange and cold storage assembly, wherein the second heat exchange and heat storage assembly is a heat storage medium circulation loop that recovers heat from compressed air or releases heat to compressed air under different operating conditions of the second turbine assembly; the cold exchange and cold storage assembly is a cold storage medium circulation loop that recovers cold energy from compressed air or releases cold energy to compressed air under different operating conditions of the second turbine assembly.

[0012] In some embodiments, the first turbine assembly includes a first compressor and a first expander, wherein the first compressor compresses gaseous carbon dioxide; and the first expander expands high-pressure carbon dioxide to generate electricity.

[0013] In some embodiments, the first heat exchange and heat storage assembly includes a first heat recovery unit, a first reheater, a first cold tank, and a first hot tank; the heat storage medium recovers heat from the carbon dioxide at the outlet of the first compressor in the first heat recovery unit, and uses the recovered heat in the first reheater to heat the carbon dioxide entering the first expander; the first cold tank and the first hot tank are respectively used to store heat storage medium at different temperatures.

[0014] In some embodiments, the regenerative assembly includes a first regenerator and a second regenerator; the first regenerator is used to recover the heat of the gaseous carbon dioxide output from the first heat recovery unit and heat the gaseous carbon dioxide entering the first compressor; the second regenerator recovers the heat of the carbon dioxide output from the first expander and heats the carbon dioxide entering the first regenerator.

[0015] In some embodiments, the second turbine assembly includes a second compressor and a second expander, the second compressor compressing air; the second expander compressing air to expand and generate electricity.

[0016] In some embodiments, the second heat exchange and heat storage assembly includes a heat storage medium circulation loop consisting of a second heat recovery unit, a second hot tank, a second reheater, and a second cold tank; the heat storage medium recovers the heat from the air output by the second compressor in the second heat recovery unit; and transfers the heat to the air entering the second expander in the second reheater; the second cold tank and the second hot tank are used to store heat storage medium at different temperatures.

[0017] In some embodiments, the cold exchange and cold storage assembly includes a cold storage medium circulation loop consisting of a recooler, a heat medium tank, a cold recovery unit, and a cold medium tank; the cold storage medium recovers the cold energy of the air discharged from the low-temperature tank in the cold recovery unit, and cools the air output from the second heat recovery unit in the recooler; the cold recovery unit and the cold medium tank are used to store cold storage medium at different temperatures.

[0018] In some embodiments, the refrigeration unit includes a compression end and an expansion end. The air output from the recooler expands and depressurizes and cools down through the expansion end. The expansion end drives the compression end, and the compression end compresses the air and outputs it to the second compressor.

[0019] According to a second aspect of this application, an energy storage method for a cryogenic medium energy storage system is proposed, which utilizes the energy storage system described in any of the above embodiments for energy storage, and includes the following process:

[0020] Energy storage stage: The cryogenic tank outputs cryogenic liquid carbon dioxide, which is vaporized by the cryogenic cold storage body, and then compressed to a high temperature and high pressure state by the first turbine assembly. The heat in the compression process is recovered to liquefy the gaseous carbon dioxide, resulting in room temperature high pressure liquid carbon dioxide, which is then stored in a room temperature tank. At the same time, the air is compressed by the refrigerator, and the compressed air is then compressed and pressurized by the second turbine assembly. The heat in the compression and pressurization process is recovered by the heat exchange assembly. The compressed air then flows back to the refrigerator to depressurize and cool down before being delivered to the air chamber.

[0021] Energy release stage: The ambient temperature tank outputs ambient temperature high pressure liquid carbon dioxide, which is heated and vaporized and then fed into the first turbine component to generate electricity and reduce temperature and pressure; the gaseous carbon dioxide after doing work is cooled and liquefied by the low temperature cold storage body and then fed into the liquid chamber; at the same time, air is output from the air chamber, and after being heated by the heat exchange component, it enters the second turbine component to generate electricity and is then discharged.

[0022] In some embodiments, during the energy storage phase, a portion of the carbon dioxide gas output from the upper part of the ambient temperature tank is condensed and returned to the ambient temperature tank to maintain the gas pressure stability of the ambient temperature tank; during the energy release phase, after the ambient temperature high-pressure liquid carbon dioxide is heated and vaporized, a portion of the carbon dioxide gas is injected into the ambient temperature tank to maintain the gas pressure stability of the ambient temperature tank.

[0023] Additional aspects and advantages of this application will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of this application. Attached Figure Description

[0024] The above and / or additional aspects and advantages of this application will become apparent and readily understood from the following description of the embodiments taken in conjunction with the accompanying drawings, wherein:

[0025] Figure 1 This is a schematic diagram of the structure of a cryogenic dielectric energy storage system proposed in an embodiment of this application;

[0026] Figure 2 This is a schematic diagram of the structure of a cryogenic dielectric energy storage system proposed in an embodiment of this application;

[0027] Figure 3 This is a schematic diagram of the structure of a cryogenic dielectric energy storage system proposed in an embodiment of this application;

[0028] Figure 4 This is a flowchart of a method for cryogenic dielectric energy storage according to an embodiment of this application;

[0029] In the diagram, 1. First energy storage subsystem; 11. Cryogenic tank; 12. Cryogenic cold storage body; 13. First turbine assembly; 131. First compressor; 132. First expander; 14. First heat exchange and heat storage assembly; 141. First heat recovery unit; 142. First reheater; 143. First cold tank; 144. First hot tank; 15. Regeneration assembly; 151. First regenerator; 152. Second regenerator; 16. Gas-liquid phase change assembly; 161. Condenser; 162. Evaporator; 17. Ambient temperature tank;

[0030] 2. Second energy storage subsystem; 21. Second turbine assembly; 211. Second compressor; 212. Second expander; 22. Second heat exchange and thermal storage assembly; 221. Second heat recovery unit; 222. Second reheater; 223. Second cold tank; 224. Second hot tank; 23. Cold exchange and cold storage assembly; 231. Recooler; 232. Cold recovery unit; 233. Cold medium tank; 234. Thermal medium tank; 235. Refrigeration unit. Detailed Implementation

[0031] The embodiments of this application are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this application, and should not be construed as limiting this application. Rather, the embodiments of this application include all variations, modifications, and equivalents falling within the spirit and scope of the appended claims.

[0032] See Figure 1 To achieve the above objectives, this application proposes a cryogenic energy storage system comprising a first energy storage subsystem 1 and a second energy storage subsystem 2. The first energy storage subsystem 1 includes a cryogenic tank 11 and an ambient temperature tank 17, which are interconnected and used to store liquid carbon dioxide at different temperatures, and a first turbine assembly 13 and a cryogenic cold storage body 12, which are respectively connected to the cryogenic tank 11 and the ambient temperature tank 17. The first turbine assembly 13 compresses carbon dioxide and generates electricity using carbon dioxide under different operating conditions. The cryogenic cold storage body 12 vaporizes liquid carbon dioxide and liquefied gaseous carbon dioxide under constant pressure under different operating conditions of the first turbine assembly 13. The cryogenic tank 11 is divided into an air chamber and a liquid chamber by a flexible diaphragm. The air chamber and liquid chamber have equal pressure, and the volume of the air chamber is adjusted by the expansion and contraction of the flexible diaphragm.

[0033] The first energy storage subsystem 1 includes a cryogenic tank 11, an ambient temperature tank 17, a first turbine assembly 13, and a cryogenic cold storage body 12. The cryogenic tank 11 is insulated from the environment and has a certain capacity for storing cryogenic liquid carbon dioxide. However, to prevent flash evaporation of the cryogenic liquid carbon dioxide, the cryogenic tank 11 is divided into an air chamber and a liquid chamber by a flexible diaphragm. The air chamber is filled with compressed air to maintain pressure and prevent flash evaporation; the liquid chamber is used to store cryogenic liquid carbon dioxide. Since the air chamber and liquid chamber are separated by the flexible diaphragm, the pressure in both chambers is the same, and their volumes are adjusted by the expansion and contraction of the flexible diaphragm. Simultaneously, the ambient temperature tank 17 stores ambient temperature liquid carbon dioxide and is insulated from the environment. The ambient temperature tank 17 is connected to the liquid chamber. During energy storage, liquid carbon dioxide is transferred from the cryogenic tank 11 to the ambient temperature tank 17; during energy release, liquid carbon dioxide is transferred from the ambient temperature tank 17 to the cryogenic tank 11.

[0034] In this embodiment, both the first turbine assembly 13 and the cryogenic storage body 12 are disposed between the cryogenic tank 11 and the ambient temperature tank 17, and are connected to both. The cryogenic storage body 12 stores the cold energy released by the vaporization of liquid carbon dioxide. Water can be used as the phase change cold storage material, or a large amount of aqueous solution or other sensible heat cold storage material can be used for small temperature difference cold storage. The carbon dioxide and the cold storage medium may exchange heat directly or indirectly. Under different operating conditions of the first turbine assembly 13, the carbon dioxide is kept at a constant pressure to vaporize into liquid carbon dioxide and liquefied gaseous carbon dioxide. For example, during the energy storage stage, the cryogenic tank 11 outputs cryogenic liquid carbon dioxide, which releases cold energy and vaporizes through the cryogenic storage body 12. During the energy release stage, the carbon dioxide after the work is done by the first turbine assembly 13 is cooled and liquefied by the cryogenic storage body 12, and then the cryogenic liquid carbon dioxide is input into the cryogenic tank 11 for storage.

[0035] In this embodiment, the first turbine assembly 13 compresses carbon dioxide and generates electricity using carbon dioxide under different operating conditions. For example, the first turbine assembly 13 includes a first compressor 131 and a first expander 132. The first compressor 131 compresses gaseous carbon dioxide; the first expander 132 is used for high-pressure carbon dioxide expansion and generates electricity. The first compressor 131 is driven by an electric motor to compress carbon dioxide and can be in one or more stages. The first expander 132 is used for high-pressure carbon dioxide expansion and drives a generator to generate electricity and can also be in one or more stages.

[0036] The second energy storage subsystem 2, which is connected to the air cavity, includes a chiller 235, a second turbine assembly 21, and a heat exchange assembly. The second turbine assembly 21 compresses air and generates electricity by utilizing air expansion under different operating conditions. The heat exchange assembly is used to release heat / cold energy or store heat / cold energy into the compressed air in the second turbine assembly 21 under different operating conditions. The chiller 235 is connected to the second turbine assembly 21 and is used to compress air and cool the air input into the cryogenic tank 11.

[0037] The second energy storage subsystem 2 includes a chiller 235, a second turbine assembly 21, and a heat exchange assembly. The second turbine assembly 21 includes a second compressor 211 and a second expander 212. The second compressor 211 compresses air, and the second expander 212 compresses air to generate electricity. In other words, the second compressor 211 is driven by an electric motor to compress air, and can be in one or more stages. The second expander 212 compresses air to drive a generator to generate electricity, and can also be in one or more stages.

[0038] The refrigerator 235 is connected to the air chamber and the second turbine assembly 21, respectively, for compressing air and cooling the air input into the cryogenic tank 11. For example, in some embodiments, the refrigerator 235 includes a compression end and an expansion end. The air expands and depressurizes and cools down through the expansion end, and the expansion end drives the compression end, which compresses and outputs the air. Figure 1 As shown, the compression end compresses and outputs the air passing through it. The second compressor 211 is connected to the output end of the compression end and further compresses and pressurizes the compressed air. After the heat generated during the compression and pressurization process is recovered by the heat exchange component, the compressed air is depressurized and cooled by the expansion end of the refrigerator 235 before entering the air chamber.

[0039] The heat exchange components are used to release or store heat / cold energy into the compressed air in the second turbine assembly 21 under different operating conditions. For example, the heat exchange components include a second heat exchange and heat storage component 22 and a cold exchange and cold storage component 23. The second heat exchange and heat storage component 22 is a heat storage medium circulation loop, which recovers heat from the compressed air or releases heat to the compressed air under different operating conditions of the second turbine assembly 21. The cold exchange and cold storage component 23 is a cold storage medium circulation loop, which recovers cold energy from the compressed air or releases cold energy to the compressed air under different operating conditions of the second turbine assembly 21.

[0040] The main energy storage containers in this application are the ambient temperature tank 17 and the cryogenic tank 11, which store liquid carbon dioxide. Their volume is reduced by more than 90% compared to gas storage facilities, allowing for the use of ground-mounted pressure vessels with flexible site selection and a small footprint. The heat of carbon dioxide compression is used to heat the carbon dioxide expansion intake, eliminating the need for external waste heat and limiting application scenarios. Furthermore, all equipment in this application can be integrated using existing mature products and technologies, eliminating the need for new equipment development, which helps reduce investment costs and accelerate the large-scale construction of energy storage facilities. The media used in this application are all common natural media used in the industrial field, offering advantages such as safety, environmental friendliness, and low cost. Simultaneously, the process flow is simple, reliable, and has low operating and maintenance costs, facilitating unattended operation. Moreover, the carbon dioxide in this application is in a closed-loop cycle, utilizing and long-term storing carbon dioxide, contributing to the development of the CCUS industry.

[0041] In some embodiments, the first energy storage subsystem 1 further includes a first heat exchange and heat storage component 14 and a heat recovery component 15, which are respectively connected to the first turbine component 13. The first heat exchange and heat storage component is used to release or store heat to the gas carbon dioxide in the first turbine component 13 under different operating conditions. The heat recovery component is used to increase the inlet temperature of the first turbine component under different operating conditions.

[0042] The first energy storage subsystem 1 further includes a first heat exchange and storage component 14 and a heat recovery component 15, both of which are connected to the first turbine component 13. The first heat exchange and storage component 14 is used to release or store heat to the carbon dioxide gas in the first turbine component 13 under different operating conditions, and the heat recovery component 15 is used to increase the inlet temperature of the first turbine component under different operating conditions. For example, in some embodiments, the first heat exchange and storage component 14 includes a first heat recovery unit 141, a first reheater 142, a first cold tank 143, and a first hot tank 144. The heat storage medium recovers the heat of the carbon dioxide at the outlet of the first compressor 131 in the first heat recovery unit 141, and uses the recovered heat in the first reheater 142 to heat the carbon dioxide entering the first expander 132. The first cold tank 143 and the first hot tank 144 are used to store heat storage medium at different temperatures.

[0043] like Figure 2As shown, the hot-side inlet of the first heat recovery unit 141 is connected to the outlet of the first compressor 131 to recover the sensible heat of the carbon dioxide at the outlet of the first compressor 131 and transfer the heat to the heat storage medium. After absorbing heat, the heat storage medium is stored in the first hot tank 144. As the heat storage medium circulates, it enters the first reheater 142 to heat the carbon dioxide entering the first expander 132. After releasing heat, the heat storage medium enters the first cold tank 143. This cycle is repeated to release or store heat to the gaseous carbon dioxide in the first turbine assembly 13 under different operating conditions.

[0044] Similarly, in this embodiment, the regenerative assembly 15 includes a first regenerator 151 and a second regenerator 152. The first regenerator 151 is used to recover the heat of the gaseous carbon dioxide output from the first heat recovery unit 141 and heat the gaseous carbon dioxide entering the first compressor 131. The second regenerator 152 is used to recover the heat of the carbon dioxide output from the first expander 132 and heat the carbon dioxide entering the first regenerator 142. The first regenerator 151 is used to heat the intake air of the first compressor 131 with the remaining heat after the exhaust heat of the first compressor 131 is recovered by the first heat recovery unit 141. The second regenerator 152 is used to heat the intake air of the first regenerator 142 with the exhaust heat of the first expander 132. The exhaust of the first regenerator 142 then enters the first expander 132.

[0045] In some embodiments, the first energy storage subsystem 1 further includes a gas-liquid phase change component 16, which is connected to the first turbine component 13, and under different operating conditions of the first turbine component 13, it liquefies gaseous carbon dioxide or vaporizes liquid carbon dioxide while maintaining a constant pressure of carbon dioxide; the gas-liquid phase change component 16 is connected to an ambient temperature tank 17, and simultaneously inputs liquid or gaseous carbon dioxide into the ambient temperature tank 17 under different operating conditions of the first turbine component, so as to maintain the stability of the gas pressure in the ambient temperature tank 17.

[0046] The first energy storage subsystem 1 also includes a gas-liquid phase change component 16, such as... Figure 2As shown, the gas-liquid phase change assembly 16 includes a condenser 161 and an evaporator 162. The condenser 161 is connected to the hot side of the first regenerator 151, liquefying the carbon dioxide gas output from the first regenerator 151 into room-temperature, high-pressure liquid carbon dioxide. This liquid carbon dioxide is then connected to an ambient-temperature tank 17 for storage. In some embodiments, the ambient-temperature tank 17 is directly connected to the inlet of the condenser 161. During the energy storage phase, a portion of the carbon dioxide gas at the top of the ambient-temperature tank 17 is simultaneously output to the condenser 161 for liquefaction, thus maintaining stable pressure in the ambient-temperature tank 17. In this embodiment, the evaporator 162 is connected to the ambient temperature tank 17. During the energy release phase, the ambient temperature tank 17 outputs ambient temperature, high-pressure liquid carbon dioxide, which is vaporized by the evaporator 162. Simultaneously, the outlet of the evaporator 162 draws a portion of the carbon dioxide gas and fills the upper part of the ambient temperature tank 17 to maintain stable gas pressure. The outlet of the evaporator 162 is connected to the cold side of the second regenerator 152, allowing the carbon dioxide gas to be further heated. Therefore, the first turbine assembly 13 can be used to liquefy gaseous carbon dioxide or vaporize liquid carbon dioxide under different operating conditions.

[0047] In some embodiments, the second heat exchange and heat storage assembly 22 includes a heat storage medium circulation loop consisting of a second heat recovery unit 221, a second hot tank 224, a second reheater 222, and a second cold tank 223; the heat storage medium recovers the heat of the air output by the second compressor 211 in the second heat recovery unit 221; and transfers the heat to the air entering the second expander 212 in the second reheater 222; the second cold tank 223 and the second hot tank 224 are respectively used to store heat storage medium at different temperatures.

[0048] The second heat exchange and storage assembly 22 includes a second heat recovery unit 221, a second hot tank 224, a second reheater 222, and a second cold tank 223. The heat storage medium forms a circulation loop through the second heat recovery unit 221, the second hot tank 224, the second reheater 222, and the second cold tank 223. The second heat recovery unit 221 recovers the sensible heat of the air outlet from the second compressor 211 and transfers it to the heat storage medium. The second reheater 222 transfers the heat from the heat storage medium to the air entering the second expander 212. The second cold tank 223 stores the heat storage medium at a lower temperature, and the second hot tank 224 stores the heat storage medium at a higher temperature. Figures 2-3As shown, the outlet of the second compressor 211 is connected to the hot side of the second heat recovery unit 221. The sensible heat of the air at the outlet of the second compressor 211 is transferred to the heat storage medium. After absorbing heat, the heat storage medium is stored in the second hot tank 224. As the heat storage medium circulates, it enters the second reheater 222 to transfer the heat of the heat storage medium to the air entering the second expander 212. The heat storage medium after releasing heat enters the second cold tank 223. This cycle is repeated to release heat / cold energy or store heat / cold energy to the compressed air in the second turbine assembly 21 under different operating conditions.

[0049] In this embodiment, the hot side outlet of the second heat recovery unit 221 is connected to the cold exchange and storage component 23. After further recovering the heat from the carbon dioxide, the heat enters the refrigerator 235 to further cool the air input to the cryogenic tank 11 to reach the operating temperature of the cryogenic tank 11.

[0050] In some embodiments, the cold exchange and cold storage assembly 23 includes a cold storage medium circulation loop consisting of a recooler 231, a heat medium tank 234, a cold recovery unit 232, and a cold medium tank 233; the cold storage medium recovers the cold energy of the air discharged from the low-temperature tank 11 in the cold recovery unit 232, and cools the air output from the second heat recovery unit 221 in the recooler 231; the cold recovery unit 232 and the cold medium tank 233 are respectively used to store cold storage medium at different temperatures.

[0051] The recooler 231 is used to cool the exhaust gas from the second heat recovery unit 221 and transfer heat to the cold storage medium. The cold recovery unit 232 is used to transfer the cold energy of the air discharged from the low-temperature tank 11 to the cold storage medium. The cold medium tank 233 is used to store the cold storage medium at a lower temperature, and the hot medium tank 234 is used to store the cold storage medium at a higher temperature. Figure 3 As shown, the hot side outlet of the second heat recovery unit 221 is connected to the recooler 231 to cool the exhaust gas of the second heat recovery unit 221 and transfer heat to the cold storage medium. The cold storage medium that has absorbed heat enters the hot medium tank 234. As the cold storage medium circulates, it enters the cold recovery unit 232 to transfer the cold energy of the air discharged from the low temperature tank 11 to the cold storage medium. The cold storage medium that has released the cold energy enters the cold medium tank 233.

[0052] According to a second aspect of this application, an energy storage method for a cryogenic dielectric energy storage system is proposed, utilizing the energy storage system in any of the above embodiments for energy storage, such as... Figure 4 As shown, the process includes the following:

[0053] S1 Energy Storage Stage: Low-temperature liquid carbon dioxide is output from the low-temperature tank 11 and vaporized by the low-temperature cold storage body 12. It is then compressed to a high temperature and high pressure state by the first turbine assembly 13 and the heat in the compression process is recovered to liquefy the gaseous carbon dioxide, resulting in room temperature high pressure liquid carbon dioxide, which is then sent to the room temperature tank 17 for storage. At the same time, the air is compressed by the refrigerator 235, and the compressed air is then compressed and pressurized by the second turbine assembly 21 and the heat in the compression and pressurization process is recovered by the heat exchange assembly. It then flows back to the refrigerator 235 to depressurize and cool down before being sent to the air chamber.

[0054] S2 Energy Release Stage: The ambient temperature tank 17 outputs ambient temperature high pressure liquid carbon dioxide, which is heated and vaporized and then fed into the first turbine component 13 to generate electricity and reduce temperature and pressure; the gaseous carbon dioxide after doing work is cooled and liquefied by the low temperature cold storage body 12 and then fed into the liquid chamber; at the same time, air is output from the air chamber, and after being heated by the heat exchange component, it enters the second turbine component 21 to generate electricity and is then discharged.

[0055] In some embodiments, during the energy storage phase, a portion of the carbon dioxide gas output from the upper part of the ambient temperature tank 17 is condensed and returned to the ambient temperature tank 17 to maintain the gas pressure stability of the ambient temperature tank 17; during the energy release phase, after the ambient temperature high-pressure liquid carbon dioxide is heated and vaporized, a portion of the carbon dioxide gas is injected into the ambient temperature tank 17 to maintain the gas pressure stability of the ambient temperature tank 17.

[0056] Specifically, in the energy storage stage: Low-temperature tank 11 outputs low-temperature liquid carbon dioxide, which releases cold energy and vaporizes through low-temperature cold storage body 12. It is then heated by the first regenerator 151, compressed to a high-temperature, high-pressure state by the first compressor 131, and then transferred to the heat storage medium exiting the first cold tank 143 and entering the first hot tank 144 by the first heat recovery unit 141. It then releases heat through the first regenerator 151, liquefies in the condenser 161, and is finally stored in the ambient temperature tank 17. Simultaneously, a portion of the carbon dioxide gas at the top of the ambient temperature tank 17 is output to the condenser 161. 61 is liquefied together to maintain stable air pressure in ambient temperature tank 17; the low temperature tank 11 is pressurized by compressed air. During the energy storage stage, the air is compressed by the compression end of the refrigeration unit 235, and then compressed and pressurized by the second compressor 211 before being input into the second heat recovery unit 221 to transfer heat to the heat storage medium that comes out of the second cold tank 223 and enters the second hot tank 224. Then, the air is cooled by the recooler 231, which absorbs the cold energy from the cold medium that comes out of the cold medium tank 233 and enters the hot medium tank 234. The air then enters the expansion end of the refrigeration unit 235 for further depressurization and cooling, and then enters the low temperature tank 11 for storage.

[0057] Energy release stage: At room temperature, high-pressure liquid carbon dioxide output from ambient temperature tank 17 is vaporized by evaporator 162. Simultaneously, some carbon dioxide gas is drawn from the outlet of evaporator 162 and injected into the upper part of ambient temperature tank 17 to maintain stable gas pressure. It is then heated by the second regenerator 152, and then the first regenerator 142 absorbs the heat from the heat storage medium exiting the first hot tank 144 and entering the first cold tank 143. The heat is then generated by the first expander 132, which cools and depressurizes the tank, before releasing heat through the second regenerator 152. The carbon dioxide is then cooled and liquefied by the cryogenic storage tank 12, and then stored in the cryogenic tank 11. During the energy release phase, air is output from the cryogenic tank 11, and then the cold energy is transferred to the storage medium from the heat medium tank 234 and into the cold medium tank 233 by the cold recovery unit 232 and heated. The air is then input into the second reheater 222 to absorb the heat from the heat storage medium from the second heat tank 224 and into the second cold tank 223, and then discharged after generating electricity by the second expander 212.

[0058] It should be noted that in the description of this application, the terms "first," "second," etc., are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Furthermore, in the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0059] Any process or method described in the flowchart or otherwise herein can be understood as representing a module, segment, or portion of code comprising one or more executable instructions for implementing a particular logical function or process, and the scope of the preferred embodiments of this application includes additional implementations in which functions may be performed not in the order shown or discussed, including substantially simultaneously or in reverse order depending on the function involved, as will be understood by those skilled in the art to which embodiments of this application pertain.

[0060] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "example," "specific example," or "some examples," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of this application. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in at least one embodiment or example.

[0061] Although embodiments of this application have been shown and described above, it is understood that the above embodiments are exemplary and should not be construed as limiting this application. Those skilled in the art can make changes, modifications, substitutions and variations to the above embodiments within the scope of this application.

Claims

1. A cryogenic medium energy storage system, characterized by, include A first energy storage subsystem includes a cryogenic tank and an ambient temperature tank, which are interconnected and used to store liquid carbon dioxide at different temperatures, and a first turbine assembly and a cryogenic cold storage body, which are respectively connected to the cryogenic tank and the ambient temperature tank. The first turbine assembly compresses carbon dioxide and generates electricity using carbon dioxide under different operating conditions. The cryogenic cold storage body vaporizes liquid carbon dioxide or liquefies gaseous carbon dioxide under constant pressure under different operating conditions of the first turbine assembly. The cryogenic tank is divided into an air chamber and a liquid chamber by a flexible diaphragm. The air chamber and the liquid chamber have equal pressure, and the volume of the air chamber is adjusted by the expansion and contraction of the flexible diaphragm. The first energy storage subsystem also includes a gas-liquid... A phase change assembly, connected to the first turbine assembly, liquefies gaseous carbon dioxide or vaporizes liquid carbon dioxide under different operating conditions of the first turbine assembly while maintaining a constant pressure. A gas-liquid phase change assembly is connected to the ambient temperature tank, simultaneously inputting liquid or gaseous carbon dioxide into the ambient temperature tank under different operating conditions of the first turbine assembly to maintain stable pressure in the ambient temperature tank. During the energy storage phase, a portion of the carbon dioxide gas output from the upper part of the ambient temperature tank is condensed and returned to the ambient temperature tank to maintain stable pressure. During the energy release phase, after the ambient temperature high-pressure liquid carbon dioxide is heated and vaporized, a portion of the carbon dioxide gas is injected into the ambient temperature tank to maintain stable pressure. The second energy storage subsystem, connected to the air cavity, includes a chiller, a second turbine assembly, and a heat exchange assembly. The second turbine assembly compresses air and generates electricity using air expansion under different operating conditions. The heat exchange assembly releases or stores heat / cold energy into the compressed air in the second turbine assembly under different operating conditions. The chiller is connected to the second turbine assembly and is used to compress air and cool the air input to the cryogenic tank.

2. The energy storage system of claim 1, wherein, The first energy storage subsystem further includes a first heat exchange and heat storage component and a heat recovery component, which are respectively connected to the first turbine component. The first heat exchange and heat storage component is used to release or store heat to the gas carbon dioxide in the first turbine component under different operating conditions of the first turbine component. The heat recovery component is used to increase the inlet temperature of the first turbine component under different operating conditions of the first turbine component.

3. The energy storage system of claim 2, wherein, The heat exchange assembly includes a second heat exchange and heat storage assembly and a cold exchange and cold storage assembly. The second heat exchange and heat storage assembly is a heat storage medium circulation loop, which recovers heat from the compressed air or releases heat to the compressed air under different operating conditions of the second turbine assembly. The cold exchange and cold storage assembly is a cold storage medium circulation loop, which recovers cold energy from the compressed air or releases cold energy to the compressed air under different operating conditions of the second turbine assembly.

4. The energy storage system of claim 3, wherein, The first turbine assembly includes a first compressor and a first expander. The first compressor compresses gaseous carbon dioxide, and the first expander expands high-pressure carbon dioxide to generate electricity.

5. The energy storage system of claim 4, wherein, The first heat exchange and heat storage assembly includes a first heat recovery unit, a first reheater, a first cold tank, and a first hot tank; the heat storage medium recovers the heat of the carbon dioxide at the outlet of the first compressor in the first heat recovery unit, and uses the recovered heat in the first reheater to heat the carbon dioxide entering the first expander; the first cold tank and the first hot tank are used to store heat storage medium at different temperatures.

6. The energy storage system of claim 5, wherein, The regenerative assembly includes a first regenerator and a second regenerator; the first regenerator is used to recover the heat of the gaseous carbon dioxide output from the first heat recovery unit and heat the gaseous carbon dioxide entering the first compressor; the second regenerator recovers the heat of the carbon dioxide output from the first expander and heats the carbon dioxide entering the first regenerator.

7. The energy storage system of claim 6, wherein, The second turbine assembly includes a second compressor and a second expander. The second compressor compresses air, and the second expander expands the compressed air to generate electricity.

8. The energy storage system according to claim 7, characterized in that, The second heat exchange and storage component includes a heat storage medium circulation loop consisting of a second heat recovery unit, a second hot tank, a second reheater, and a second cold tank; the heat storage medium recovers the heat from the air output by the second compressor in the second heat recovery unit; and transfers the heat to the air entering the second expander in the second reheater; The second cold tank and the second hot tank are used to store heat storage media at different temperatures.

9. The energy storage system according to claim 7, characterized in that, The cold exchange and cold storage assembly includes a cold storage medium circulation loop consisting of a recooler, a heat medium tank, a cold recovery unit, and a cold medium tank; the cold storage medium recovers the cold energy of the air discharged from the low-temperature tank in the cold recovery unit, and cools the air output from the second heat recovery unit in the recooler; the cold recovery unit and the cold medium tank are used to store cold storage medium at different temperatures.

10. The energy storage system according to claim 9, characterized in that, The refrigeration unit includes a compression end and an expansion end. The air output from the recooler expands, depressurizes, and cools down through the expansion end. The expansion end drives the compression end, and the compression end compresses the air and outputs it to the second compressor.

11. An energy storage method for a cryogenic dielectric energy storage system, characterized in that, Energy storage using any one of the energy storage systems described in claims 1-10 includes the following process: Energy storage stage: The cryogenic tank outputs cryogenic liquid carbon dioxide, which is vaporized by the cryogenic cold storage body, then compressed to a high temperature and high pressure state by the first turbine assembly, and the heat in the compression process is recovered to liquefy the gaseous carbon dioxide, resulting in room temperature high pressure liquid carbon dioxide, which is then input into the room temperature tank for storage; at the same time, the air is compressed by the refrigeration unit, and the compressed air is then compressed and pressurized by the second turbine assembly, and the heat in the compression and pressurization process is recovered by the heat exchange assembly; and then flows back to the refrigeration unit to depressurize and cool down before being delivered to the air chamber; in the energy storage stage, part of the carbon dioxide gas output from the upper part of the room temperature tank is condensed and flows back to the room temperature tank to maintain the gas pressure stability of the room temperature tank; in the energy release stage, after the room temperature high pressure liquid carbon dioxide is heated and vaporized, part of the carbon dioxide gas is injected into the room temperature tank to maintain the gas pressure stability of the room temperature tank; Energy release stage: The ambient temperature tank outputs ambient temperature high pressure liquid carbon dioxide, which is heated and vaporized and then fed into the first turbine component to generate electricity and reduce temperature and pressure; the gaseous carbon dioxide after doing work is cooled and liquefied by the low temperature cold storage body and then fed into the liquid chamber; at the same time, air is output from the air chamber, and after being heated by the heat exchange component, it enters the second turbine component to generate electricity and is then discharged.

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