High-capacity and ultrahigh-temperature compressed air energy storage system and method

Abstract

The invention provides a high-capacity and ultrahigh-temperature compressed air energy storage system and method.The energy storage system comprises a first subsystem and a second subsystem, the first subsystem comprises a compression energy storage unit, a first heat storage unit, an expansion energy release unit and a starting energy recovery unit, and the compression energy storage unit comprises an air compressor unit and an air storage which are sequentially connected; the starting energy recovery unit is connected with the high-pressure exhaust end of the air compressor set, the first heat storage unit is connected with an interstage heat exchange pipeline of the air compressor set, and the expansion energy release unit is connected with the output end of the air storage. The second subsystem comprises a waste heat recovery unit, a second heat storage unit and a waste heat power generation unit, the waste heat recovery unit comprises a heat pump device, the cold end of the heat pump device is coupled with at least one cooler of the air compressor unit, and the hot end of the heat pump device and the waste heat power generation unit are connected with the second heat storage unit. According to the invention, the single-machine power and the energy conversion efficiency are greatly improved, and the requirements of a power system on large-scale, long-time and efficient energy storage are better met.

Description

Technical Field

[0001] This invention relates to the field of compressed air energy storage technology, and in particular to a large-capacity, ultra-high temperature compressed air energy storage system and method. Background Technology

[0002] With the large-scale development of new energy power generation, the proportion of intermittent power sources such as solar photovoltaic and wind power continues to rise, while the installed capacity of traditional adjustable power sources such as thermal power is gradually declining. The power grid faces severe challenges in terms of power balance and frequency stability. Against this backdrop, developing grid-scale, long-term energy storage and peak-shaving technologies has become a core requirement for improving the absorption capacity of new energy sources and ensuring the safe and stable operation of the power system.

[0003] Currently, pumped hydro storage remains the most mature large-scale, long-duration energy storage and peak-shaving technology. However, its construction is severely constrained by specific terrain and topography, with limited exploitable resources. Furthermore, it suffers from high initial investment and long construction periods, making it difficult to fully meet the future demands of new power systems for energy storage scale and deployment flexibility. In contrast, compressed air energy storage technology, due to its advantages such as flexible site selection and high capacity configuration freedom, is rapidly moving from demonstration to industrialization and is considered one of the most promising alternative technologies in the field of large-scale, long-duration energy storage.

[0004] Currently, mainstream compressed air energy storage technologies mainly follow two adiabatic compression routes: medium-temperature and high-temperature. The medium-temperature adiabatic compression route typically operates at a discharge temperature not exceeding 200°C, using medium-pressure water as the heat storage medium, resulting in a relatively complex system. The high-temperature adiabatic compression route, on the other hand, raises the discharge temperature to generally no more than 360°C, employing a combination of heat transfer oil or ternary molten salt with medium-pressure water for heat storage. However, both routes face the common bottleneck of low energy utilization efficiency, hindering their economic viability and large-scale application prospects. Furthermore, as system capacity increases, the required air volume, storage tank volume, and cost rise accordingly. The energy waste caused by releasing high-pressure air during dynamic processes such as compressor start-up and shutdown further impacts overall energy efficiency and economics. Summary of the Invention

[0005] The purpose of this invention is to provide a large-capacity, ultra-high temperature compressed air energy storage system to solve the problems mentioned above.

[0006] The technical solution adopted in this invention is: a large-capacity, ultra-high temperature compressed air energy storage system, which includes:

[0007] The first subsystem includes at least a compression energy storage unit, a first thermal energy storage unit, an expansion energy release unit, and a start-up energy recovery unit. The compression energy storage unit includes an air compressor unit and a gas storage tank connected in sequence. The start-up energy recovery unit can be selectively connected to the high-pressure exhaust end of the air compressor unit. The first thermal energy storage unit is connected to the interstage heat exchange pipeline of the air compressor unit. The expansion energy release unit is connected to the output end of the gas storage tank.

[0008] The second subsystem includes at least a waste heat recovery unit, a second heat storage unit, and a waste heat power generation unit. The waste heat recovery unit includes a heat pump device. The cold end of the heat pump device is coupled to at least one cooler of the air compressor unit. The hot end of the heat pump device is connected to the second heat storage unit. The waste heat power generation unit is connected to the second heat storage unit.

[0009] Preferably, the compressed energy storage unit includes a first compressor, a first salt gas heat exchanger, a first water gas heat exchanger, a first cooler, a second compressor, a second salt gas heat exchanger, a second water gas heat exchanger, a second cooler, and the gas storage tank connected in series. The first salt gas heat exchanger is configured to output high-temperature molten salt at a first temperature, and the second salt gas heat exchanger is configured to output high-temperature molten salt at a second temperature, wherein the second temperature is lower than the first temperature.

[0010] Preferably, the cold end of the heat pump device is coupled to the cooling medium side of the first cooler and the cooling medium side of the second cooler, respectively.

[0011] Preferably, the first thermal storage unit includes:

[0012] The first high-temperature molten salt tank and the first low-temperature molten salt tank are both connected to the salt side of the first salt gas heat exchanger.

[0013] The second high-temperature molten salt tank and the second low-temperature molten salt tank are both connected to the salt side of the second salt gas heat exchanger;

[0014] The high-temperature water tank and the low-temperature water tank are connected to the water side of the first water-gas heat exchanger and the second water-gas heat exchanger.

[0015] Preferably, the expansion energy release unit includes a first generator, and a first water-gas heater, a first salt gas heater, a first expander, a second water-gas heater, a second salt gas heater, and a second expander connected in series. The first generator is driven by the first expander and the second expander. The heat source of the first salt gas heater comes from the high-temperature molten salt output from the second salt gas heat exchanger, and the heat source of the second salt gas heater comes from the high-temperature molten salt output from the first salt gas heat exchanger.

[0016] Preferably, the second compressor includes a second compression cylinder A and a second compression cylinder B arranged in series, and the first compressor, the second compression cylinder A and the second compression cylinder B are each driven by an independent drive motor.

[0017] Preferably, the start-up energy recovery unit includes at least a third expander, a second generator, and a battery. The air inlet of the third expander can be selectively connected to the high-pressure exhaust end of the air compressor unit. The second generator is driven by the third expander, and its power output end is connected to the battery.

[0018] Preferably, the second energy storage unit includes a third high-temperature molten salt tank and a third low-temperature molten salt tank, which are connected to the hot end of the heat pump device.

[0019] Preferably, the waste heat power generation unit includes a steam turbine generator set, and the heat source input end of the steam turbine generator set is connected to the second heat storage unit.

[0020] The technical solution of the present invention also includes: a large-capacity, ultra-high temperature compressed air energy storage method, which is implemented using the above-mentioned large-capacity, ultra-high temperature compressed air energy storage system.

[0021] The beneficial effects of this invention include: This solution achieves a breakthrough in significantly improving single-unit power and energy conversion efficiency, providing key technical support for meeting the power system's demand for large-scale, long-term, and efficient energy storage. Based on system-level optimized design, this invention increases the single-unit power of compressed air energy storage from the current 300MW level to the 600MW level, achieving a leapfrog performance breakthrough. Through meticulous management of the entire energy flow process, the system's cycle efficiency is increased to over 75%, making it comparable to mature pumped hydro storage technology in terms of efficiency. This significant advancement, combined with the increased energy storage density brought about by ultra-high temperature compression and deep cooling, the efficient thermal energy conversion achieved through staged heat storage and reverse matching, the reduced energy loss due to start-up kinetic energy recovery, and the system compactness and waste heat value-added utilization brought about by heat pump coupling, together constitute a high-efficiency, high-power, low-cost, and easily engineering-promotable large-capacity compressed air energy storage system solution, powerfully promoting the large-scale commercial application and development of compressed air energy storage technology. Attached Figure Description

[0022] Figure 1 This is a structural schematic diagram of an embodiment of the present invention.

[0023] In the picture:

[0024] 1. First compressor; 2. First brine heat exchanger; 3. First water-gas heat exchanger; 4. First cooler; 5. Second compression cylinder A; 6. Second compression cylinder B; 7. Second brine heat exchanger; 8. Second water-gas heat exchanger; 9. Second cooler; 10. Gas storage tank; 11. First water-gas heater; 12. First brine heater; 13. First expander; 14. Second water-gas heater; 15. Second brine heater; 16. Second expander; 17. ... 18. Generator; 19. First high-temperature molten salt tank; 20. First low-temperature molten salt tank; 21. Second high-temperature molten salt tank; 22. High-temperature water tank; 23. Low-temperature water tank; 24. Drive motor; 25. Drive motor; 26. Drive motor; 27. Steam turbine generator set; 28. Third low-temperature molten salt tank; 29. ​​Heat pump unit; 30. Third high-temperature molten salt tank; 31. Third expander; 32. Second generator; 33. Storage battery. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0026] In the description of the embodiments of this invention, it should be understood that the terms "top," "bottom," etc., indicating orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In the description of this invention, it should be noted that unless otherwise explicitly specified and limited, the terms "set" and "connected" should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral connection; it can refer to a direct connection or an indirect connection through an intermediate medium; it can refer to the internal communication of two elements. Those skilled in the art can understand the specific meaning of the above terms in this invention through specific circumstances.

[0027] Reference Appendix Figure 1This invention provides a large-capacity, ultra-high temperature compressed air energy storage system, comprising a first subsystem and a second subsystem. The first subsystem includes at least a compression energy storage unit, a first heat storage unit, an expansion energy release unit, and a start-up energy recovery unit. The compression energy storage unit includes an air compressor unit and an air storage tank 10 connected in sequence. The start-up energy recovery unit is selectively connected to the high-pressure exhaust end of the air compressor unit. The first heat storage unit is connected to the interstage heat exchange pipeline of the air compressor unit, and the expansion energy release unit is connected to the output end of the air storage tank 10. The second subsystem includes at least a waste heat recovery unit, a second heat storage unit, and a waste heat power generation unit. The waste heat recovery unit includes a heat pump device 29. The cold end of the heat pump device 29 is coupled to at least one cooler of the air compressor unit, and the hot end of the heat pump device 29 is connected to the second heat storage unit. The waste heat power generation unit is connected to the second heat storage unit.

[0028] This invention significantly improves the energy utilization efficiency of a compressed air energy storage system by integrating a startup energy recovery unit, a waste heat recovery unit, and a waste heat power generation unit. The startup energy recovery unit addresses the inherent technical limitations of the air compressor unit's startup process. Since air compressors cannot start under pressure, the system pressure must be balanced during startup to avoid pressure buildup and ensure a safe and stable startup. Traditional systems directly discharge this high-pressure air, resulting in energy waste. This system effectively recovers the energy lost during startup by incorporating a startup energy recovery device. The waste heat recovery unit uses a heat pump device 29 instead of a traditional cooling tower. Traditional cooling towers not only occupy a large area and have high construction costs, but also directly discharge a large amount of low-temperature waste heat into the atmosphere, resulting in thermal energy waste. This system recovers this low-temperature waste heat through the heat pump device 29. This heat heat is used to heat the heat storage medium to power the waste heat power generation unit, and the generated cold energy is used to deeply cool the compressed air. This not only improves the system's thermal energy utilization rate but also significantly reduces compression power consumption. Furthermore, by increasing the air density within the air storage tank 10, the volume requirement and construction cost of the air storage tank 10 are effectively reduced.

[0029] The compression energy storage unit includes a first compressor 1, a first brine heat exchanger 2, a first water-gas heat exchanger 3, a first cooler 4, a second compressor, a second brine heat exchanger 7, a second water-gas heat exchanger 8, a second cooler 9, and a gas storage tank 10 connected in series. The first brine heat exchanger 2 is configured to output high-temperature molten salt at a first temperature, and the second brine heat exchanger 7 is configured to output high-temperature molten salt at a second temperature, which is lower than the first temperature. The expansion energy release unit includes a first generator 17, and a first water-gas heater 11, a first brine heat heater 12, a first expander 13, a second water-gas heater 14, a second brine heat heater 15, and a second expander 16 connected in series. The first generator 17 is driven by the first expander 13 and the second expander 16. The gas-side inlet of the first water-gas heater 11 is connected to the outlet of the gas storage tank 10. The heat source of the first brine heat heater 12 comes from the high-temperature molten salt output by the second brine heat exchanger 7, and the heat source of the second brine heat heater 15 comes from the high-temperature molten salt output by the first brine heat exchanger 2.

[0030] The above configuration reflects the synergistic optimization of the compressed air energy storage system's thermodynamic cycle design in this solution. In the compression energy storage unit, multi-stage heat exchange achieves graded recovery of compression heat, producing first-temperature high-temperature molten salt and second-temperature high-temperature molten salt respectively. In the expansion energy release unit, this solution fully considers the inherent characteristics of the sliding pressure operation of the large-capacity gas storage tank 10. During the energy release process, the pressure of the gas storage tank 10 continuously decreases, causing the first expander 13, located downstream, to be in a state of variable operating conditions and inlet pressure deviating from the design value for a long time. Its actual operating cylinder efficiency is significantly lower than that of the second expander 16, which operates under stable conditions. To address this phenomenon, the system innovatively adopts a "reverse temperature matching" strategy: the relatively lower-temperature second-temperature high-temperature molten salt is used to heat the inlet air of the first expander 13, which has a lower cylinder efficiency, while the higher-temperature first-temperature high-temperature molten salt is used to heat the inlet air of the second expander 16, which has a higher cylinder efficiency. This "efficiency-based heat matching" design ensures that high-grade thermal energy is fully utilized in stages with higher conversion efficiency, thereby maximizing the overall enthalpy drop and power generation at the system level.

[0031] Specifically, regarding temperature control, this solution implements a parameter system that precisely matches thermodynamic characteristics: the first compressor 1 compresses air to 420±5℃, then the first salt-gas heat exchanger 2 cools the air to 190±5℃, producing high-grade molten salt at 410±5℃ (i.e., high-temperature molten salt at the first temperature), then the first water-gas heat exchanger 3 further cools the air to 70±5℃, producing high-temperature water at 180±5℃, and finally the first cooler 4 cools the air to... After being heated to 15±5℃, the air enters the second compressor; the second compressor compresses the air to 376~445℃, and the air is cooled to 190±5℃ by the second salt gas heat exchanger 7, producing medium-grade molten salt at 395±5℃ (i.e., high-temperature molten salt at the second temperature). The air is then cooled to 70±5℃ by the second water gas heat exchanger 8, producing high-temperature water at 180±5℃. Finally, the air is cooled to 15±5℃ by the second cooler 9 and enters the gas storage tank 10.

[0032] Compared to the existing technology's maximum compression exhaust temperature of 360℃, this solution achieves "ultra-high temperature compression" by optimizing the compression energy storage unit, significantly improving the compression ratio. Under the same air compressor displacement, it can generate compressed air with higher pressure, directly increasing the energy storage density per unit mass of air. At the same time, the system uses heat pump device 29 to deeply cool the compressed air to 15±5℃, further reducing the air specific volume and improving the volume utilization rate of the air storage tank 10. Meanwhile, heat pump device 29 absorbs the waste heat of the first subsystem, improving heating efficiency.

[0033] This synergistic design of "ultra-high temperature compression" and "deep cooling" simultaneously increases the pressure energy and storage density of air, resulting in a significant reduction in the total amount of gas required and the volume of the gas storage tank for the same energy storage scale. This greatly reduces the system construction cost and footprint, providing key technical support for the economic feasibility and engineering promotion of large-capacity compressed air energy storage.

[0034] More specifically, the first thermal storage unit includes: a first high-temperature molten salt tank 18, a first low-temperature molten salt tank 19, a second high-temperature molten salt tank 20, a second low-temperature molten salt tank 21, a high-temperature water tank 22, and a low-temperature water tank 23. The first high-temperature molten salt tank 18 and the first low-temperature molten salt tank 19 are connected to the salt side of the first salt-gas heat exchanger 2 to achieve the cyclic storage and release of high-grade molten salt during system operation. The second high-temperature molten salt tank 20 and the second low-temperature molten salt tank 21 are connected to the salt side of the second salt-gas heat exchanger 7 to achieve the cyclic storage and release of medium-grade molten salt during system operation. The high-temperature water tank 22 and the low-temperature water tank 23 are connected to the water side of the first water-gas heat exchanger 3 and the second water-gas heat exchanger 8 to achieve the cyclic storage and release of water during system operation.

[0035] Through the configuration of the first thermal storage unit, the system achieves graded and orderly storage of high, medium and low grade thermal energy generated during the compression process. This not only significantly improves the thermal energy recovery efficiency, but also provides stable and matching heat source conditions for the subsequent expansion and energy release stage, further supporting the optimization and efficiency improvement of the overall thermal cycle of the system.

[0036] In specific implementation, the inlet of the first compressor 1 is connected to the atmosphere, and the outlet is connected to the gas-side inlet of the first salt gas heat exchanger 2. The gas-side outlet of the first salt gas heat exchanger 2 is connected to the gas-side inlet of the first water gas heat exchanger 3. The gas-side outlet of the first water gas heat exchanger 3 is connected to the gas-side inlet of the first cooler 4. The gas-side outlet of the first cooler 4 is connected to the inlet of the second compressor. The outlet of the second compressor is connected to the gas-side inlet of the second salt gas heat exchanger 7. The gas-side outlet of the second salt gas heat exchanger 7 is connected to the gas-side inlet of the second water gas heat exchanger 8. The gas-side outlet of the second water gas heat exchanger 8 is connected to the gas-side inlet of the second cooler 9. The gas-side outlet of the second cooler 9 is connected to the inlet of the gas storage tank 10, thus forming a series multi-stage compression and cooling energy storage gas circuit.

[0037] The inlet of the first high-temperature molten salt tank 18 is connected to the salt-side outlet of the first salt-gas heat exchanger 2, and the outlet of the first high-temperature molten salt tank 18 is connected to the salt-side inlet of the second salt-gas heater 15. The outlet of the first low-temperature molten salt tank 19 is connected to the salt-side inlet of the first salt-gas heat exchanger 2, and the inlet of the first low-temperature molten salt tank 19 is connected to the salt-side outlet of the second salt-gas heater 15. The inlet of the second high-temperature molten salt tank 20 is connected to the salt-side outlet of the second salt-gas heat exchanger 7, and the outlet of the second high-temperature molten salt tank 20 is connected to the salt-side inlet of the first salt-gas heater 12. The outlet of the second low-temperature molten salt tank 21 is connected to the salt-side inlet of the second salt-gas heat exchanger 7, and the inlet of the second low-temperature molten salt tank 21 is connected to the salt-side outlet of the first salt-gas heater 12, thereby forming a molten salt circulation loop.

[0038] The inlet of the high-temperature water tank 22 is connected to the water-side outlet of the first water-gas heat exchanger 3 and the water-side outlet of the second water-gas heat exchanger 8. The outlet of the high-temperature water tank 22 is connected to the water-side inlet of the first water-gas heater 11 and the water-side inlet of the second water-gas heater 14. The outlet of the low-temperature water tank 23 is connected to the water-side inlet of the first water-gas heat exchanger 3 and the second water-gas heat exchanger 8. The inlet of the low-temperature water tank 23 is connected to the water-side outlet of the first water-gas heater 11 and the water-side outlet of the second water-gas heater 14, thus forming a water circulation loop.

[0039] The gas-side inlet of the first water-gas heater 11 is connected to the outlet of the gas storage tank 10. The gas-side outlet of the first water-gas heater 11 is connected to the gas-side inlet of the first salt gas heater 12. The gas-side outlet of the first salt gas heater 12 is connected to the inlet of the first expander 13. The inlet of the first expander 13 is connected to the gas-side inlet of the second water-gas heater 14. The gas-side outlet of the second water-gas heater 14 is connected to the gas-side inlet of the second salt gas heater 15. The gas-side outlet of the second salt gas heater 15 is connected to the inlet of the second expander 16. The outlet of the second expander 16 is connected to the atmosphere. The first expander 13 and the second expander 16 are respectively connected to the rotor shaft of the first generator 17, which together drive the first generator 17 to output electrical energy, thus forming a two-stage expansion and co-generation energy release circuit.

[0040] In some preferred embodiments, the second compressor includes a second compression cylinder A5 and a second compression cylinder B6 arranged in series. The first compressor 1, the second compression cylinder A5, and the second compression cylinder B6 are each driven by an independent drive motor, as shown in the attached figure. Figure 1 As shown, the first compressor 1 is driven by drive motor 24, the second compression cylinder A5 is driven by drive motor 25, and the second compression cylinder B6 is driven by drive motor 26. In this configuration, the second compression cylinder A5 compresses air to 275~298℃, and its outlet is directly connected to the inlet of the second compression cylinder B6. The second compression cylinder B6 further compresses the air to 376~445℃, and there is no interstage cooling between the two stages. This independent cylinder drive structure design not only effectively copes with the high power consumption and extreme mechanical load faced by the second stage compression, improving the stability of system operation, but also creates favorable conditions for subsequent high-temperature heat exchange and heat energy recovery by maintaining a high interstage exhaust temperature. It is one of the key technical measures to achieve ultra-high temperature compression and thus improve the overall system efficiency and power level.

[0041] Of course, if the space layout and investment cost allow, a third compressor (not shown in the attached figure) can be added in series after the second compressor, and the second and third compressors can be driven by drive motors respectively. This configuration has the same technical effect as the independent drive scheme used by the second compression cylinder A5 and the second compression cylinder B6 mentioned above in terms of operating principle and system gain.

[0042] In this embodiment, the cold end of the heat pump device 29 is coupled to the cooling medium side of the first cooler 4 and the cooling medium side of the second cooler 9, respectively; the second energy storage unit includes a third high-temperature molten salt tank 30 and a third low-temperature molten salt tank 28, which are connected to the hot end of the heat pump device 29; the waste heat power generation unit includes a steam turbine generator set 27, whose heat source input end is connected to the second heat storage unit. In this configuration, the low-temperature waste heat recovered by the heat pump device 29 is converted into high-temperature heat energy and stored in the third high-temperature molten salt tank 30, which is used to drive the steam turbine generator set 27 to generate electricity, thus realizing the deep utilization and value-added conversion of the low-grade waste heat of the system.

[0043] This integrated design not only further improves the overall thermoelectric conversion efficiency of the system, but also enables the energy flow of the entire energy storage system to form a complete closed loop from air compression, heat recovery, cold energy utilization to waste heat power generation, thereby maximizing the overall energy efficiency and economy of the system while achieving large-scale, long-term energy storage.

[0044] As a non-limiting example, in this embodiment, the first high-temperature molten salt tank 18, the first low-temperature molten salt tank 19, the second high-temperature molten salt tank 20, and the second low-temperature molten salt tank 21 operate at relatively low temperatures, so a low-melting-point ternary salt system can be used, such as a mixture of 53% potassium nitrate (KNO3), 40% sodium nitrite (NaNO2), and 7% sodium nitrate (NaNO3). The third high-temperature molten salt tank 30 and the third low-temperature molten salt tank 28 operate at relatively high temperatures, so a binary salt system with better temperature resistance can be used, such as a mixture of 60% sodium nitrate (NaNO3) and 40% potassium nitrate (KNO3). This differentiated molten salt configuration achieves optimized storage and efficient utilization of thermal energy of different temperature zones and grades.

[0045] Reference Appendix Figure 1 The energy recovery unit includes a third expander 31, a second generator 32, and a battery 33. The air inlet of the third expander 31 can be selectively connected to the high-pressure exhaust end of the air compressor unit. The second generator 32 is driven by the third expander 31, and its power output is connected to the battery 33. Thus, during the system startup phase, the high-pressure air that would otherwise be discharged is introduced into the third expander 31 to perform work, driving the second generator 32 to generate electricity, which is then stored in the battery 33. This configuration allows the system to effectively recover the kinetic energy of compressed air that would otherwise be wasted during startup, converting it into usable electrical energy, thereby improving the overall energy efficiency and economy of the system during start-up and shutdown.

[0046] The method of energy storage and release using this system is as follows: the first and second subsystems work together to store energy during the off-peak period and release energy and generate electricity on the grid during the peak period, respectively. The electrical energy converted by the energy recovery unit during the system startup process can be stored in the battery 33. This electrical energy can be used to power the system's own auxiliary equipment to reduce the plant's power consumption rate, or it can be transferred for use according to the grid demand or dispatch instructions, thereby improving the economy and flexibility of the system operation.

[0047] This embodiment also provides a method for large-capacity, ultra-high temperature compressed air energy storage, which is implemented using the above-mentioned large-capacity, ultra-high temperature compressed air energy storage system.

[0048] Compared with existing technologies, this invention has achieved a breakthrough in significantly improving single-unit power and energy conversion efficiency, providing key technical support for meeting the power system's demand for large-scale, long-term, and efficient energy storage. Based on system-level optimized design, this invention increases the single-unit power of compressed air energy storage from the current 300MW level to the 600MW level, achieving a leapfrog performance improvement. Through meticulous management of the entire energy flow process, the system's cycle efficiency is increased to over 75%, making it comparable to mature pumped hydro storage technology in terms of efficiency. This significant advancement, combined with the increased energy storage density brought about by ultra-high temperature compression and deep cooling, the efficient thermal energy conversion achieved through staged thermal storage and reverse matching, the reduced energy loss due to start-up kinetic energy recovery, and the system compactness and waste heat value-added utilization brought about by heat pump coupling, together constitute a high-efficiency, high-power, low-cost, and easily engineering-promotable large-capacity compressed air energy storage system solution, powerfully promoting the large-scale commercial application and development of compressed air energy storage technology.

[0049] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A large-capacity, ultra-high temperature compressed air energy storage system, characterized in that, include: The first subsystem includes at least a compression energy storage unit, a first thermal energy storage unit, an expansion energy release unit, and a start-up energy recovery unit. The compression energy storage unit includes an air compressor unit and a gas storage tank connected in sequence. The start-up energy recovery unit can be selectively connected to the high-pressure exhaust end of the air compressor unit. The first thermal energy storage unit is connected to the interstage heat exchange pipeline of the air compressor unit. The expansion energy release unit is connected to the output end of the gas storage tank. The second subsystem includes at least a waste heat recovery unit, a second heat storage unit, and a waste heat power generation unit. The waste heat recovery unit includes a heat pump device. The cold end of the heat pump device is coupled to at least one cooler of the air compressor unit. The hot end of the heat pump device is connected to the second heat storage unit. The waste heat power generation unit is connected to the second heat storage unit.

2. The large-capacity, ultra-high temperature compressed air energy storage system according to claim 1, characterized in that, The compressed energy storage unit includes a first compressor, a first salt gas heat exchanger, a first water gas heat exchanger, a first cooler, a second compressor, a second salt gas heat exchanger, a second water gas heat exchanger, a second cooler, and the gas storage tank connected in series. The first salt gas heat exchanger is configured to output high-temperature molten salt at a first temperature, and the second salt gas heat exchanger is configured to output high-temperature molten salt at a second temperature, which is lower than the first temperature.

3. The large-capacity, ultra-high temperature compressed air energy storage system according to claim 2, characterized in that, The cold end of the heat pump device is coupled to the cooling medium side of the first cooler and the cooling medium side of the second cooler, respectively.

4. The large-capacity, ultra-high temperature compressed air energy storage system according to claim 2, characterized in that, The first thermal storage unit includes: The first high-temperature molten salt tank and the first low-temperature molten salt tank are both connected to the salt side of the first salt gas heat exchanger. The second high-temperature molten salt tank and the second low-temperature molten salt tank are both connected to the salt side of the second salt gas heat exchanger; The high-temperature water tank and the low-temperature water tank are connected to the water side of the first water-gas heat exchanger and the second water-gas heat exchanger.

5. The large-capacity, ultra-high temperature compressed air energy storage system according to any one of claims 2-4, characterized in that, The expansion energy release unit includes a first generator, and a first water-gas heater, a first salt gas heater, a first expander, a second water-gas heater, a second salt gas heater, and a second expander connected in series. The first generator is driven by the first expander and the second expander. The heat source of the first salt gas heater comes from the high-temperature molten salt output from the second salt gas heat exchanger, and the heat source of the second salt gas heater comes from the high-temperature molten salt output from the first salt gas heat exchanger.

6. The large-capacity, ultra-high temperature compressed air energy storage system according to claim 5, characterized in that, The second compressor includes a second compression cylinder A and a second compression cylinder B arranged in series. The first compressor, the second compression cylinder A, and the second compression cylinder B are each driven by an independent drive motor.

7. The large-capacity, ultra-high temperature compressed air energy storage system according to any one of claims 1-4, 6, is characterized in that, The start-up energy recovery unit includes at least a third expander, a second generator, and a battery. The air inlet of the third expander can be selectively connected to the high-pressure exhaust end of the air compressor unit. The second generator is driven by the third expander, and its power output end is connected to the battery.

8. The large-capacity, ultra-high temperature compressed air energy storage system according to claim 7, characterized in that, The second energy storage unit includes a third high-temperature molten salt tank and a third low-temperature molten salt tank, which are connected to the hot end of the heat pump device.

9. The large-capacity, ultra-high temperature compressed air energy storage system according to claim 7, characterized in that, The waste heat power generation unit includes a steam turbine generator set, and the heat source input end of the steam turbine generator set is connected to the second heat storage unit.

10. A method for large-capacity, ultra-high temperature compressed air energy storage, characterized in that, The system is implemented using the large-capacity, ultra-high temperature compressed air energy storage system described in any one of claims 1-9.

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