Coupled solar energy double-shell near-isothermal compressed air energy storage system and operation method

Abstract

The application discloses a double-shell near-isothermal compressed air energy storage system coupled with solar energy and an operation method thereof. The system combines the advantages of compressed air energy storage, an ejector, a double-tank liquid piston, a heat accumulator and solar light heat, uses the exhaust heat after energy release, the solar light heat stored in the gap between energy storage and energy release and the heat accumulator heat after energy release to heat air as insulation gas to insulate air in the double-shell air storage tank, reasonably uses the exhaust heat after energy release, realizes step-by-step utilization of energy, reasonably uses the heat stored in the gap between energy storage and energy release and the heat accumulator, reduces heat loss of the heat accumulator during the period, improves the output stability of the system in the later energy release stage and the insufficient light period, reduces the cost of the air storage chamber, solves the problems of the exhaust heat in the existing compressed air energy storage system, the economy of the air storage chamber, the heat loss in the air storage process in the air storage chamber, the energy storage density and the low density of the compressed air energy storage system.

Description

Technical Field

[0001] This invention belongs to the field of compressed air energy storage coupled with renewable energy technology, specifically relating to a double-shell near-isothermal compressed air energy storage system coupled with solar energy and its operation method. Background Technology

[0002] Solar energy is clean, renewable, pollution-free, widely available, inexhaustible, reduces energy consumption, lowers energy costs, can be used in remote areas, and has no transportation costs. However, it is limited by sunlight and weather conditions.

[0003] Compressed air energy storage (CASS) is an energy storage and release technology. Its basic principle is to convert off-peak electricity into energy in compressed air, store the compressed air, and release it when needed, converting it back into electricity. CASS has made significant progress over the past few decades. With increasing energy demand and the development of renewable energy, the need for energy storage technology is becoming increasingly urgent. Due to its renewable, flexible, and environmentally friendly characteristics, CASS has become one of the most watched energy storage technologies.

[0004] Compressed air energy storage technology has a wide range of applications. It can be used for peak-valley regulation in power systems, power supply assurance for microgrids and offshore power grids, and energy recovery in industrial processes. Furthermore, with the development of electric vehicles and other related fields, compressed air energy storage technology can also be used in the transportation sector.

[0005] In traditional compressed air energy storage systems, the energy conversion efficiency is typically around 50%, resulting in low energy storage efficiency. As the energy release process proceeds, the heat exchange capacity of the accumulator decreases, leading to unstable output power. Even after energy release, some heat remains in the accumulator, further contributing to the low energy conversion efficiency of the energy storage system.

[0006] Furthermore, compressed air energy storage systems require large equipment and storage facilities, which increases costs and space requirements. Storage tanks are a crucial component of compressed air energy storage technology. They are devices used to store compressed air and are typically made of steel or composite materials. Storage tanks need to be able to withstand the high pressure of compressed air and require sufficient strength and pressure resistance, significantly increasing investment costs for large-scale compressed air energy storage systems. Summary of the Invention

[0007] To address the issues of exhaust waste heat, high construction costs of gas storage chambers, heat loss during gas storage, low energy density, and significant waste of solar energy resources in existing compressed air energy storage systems, a dual-shell near-isothermal compressed air energy storage system coupled with solar energy and its operation method are proposed. This system combines the advantages of compressed air energy storage, ejectors, dual-tank liquid pistons, accumulators, and solar thermal energy.

[0008] To achieve the above objectives, the technical solution adopted by this invention is: a double-shell near-isothermal compressed air energy storage system coupled with solar energy, comprising a compressed air energy storage unit, a dual-tank liquid piston unit, and an energy release unit; the compressed air energy storage unit is provided with a double-shell gas storage unit, and a high-pressure gas storage chamber and a medium-pressure gas storage chamber are nested within the double-shell gas storage unit; the medium-pressure gas storage chamber has an insulated gas channel on its outer side, and the outlet of the compressed air energy storage unit is connected to the inlet of the dual-tank liquid piston unit and the medium-pressure gas storage chamber of the double-shell gas storage unit. The outlet of the dual-tank liquid piston unit is connected to the high-pressure gas storage chamber of the dual-shell gas storage unit. The energy release unit is sequentially connected to the second accumulator, the first expander, the first accumulator, the solar thermal accumulator, and the second expander. The outlets of the first accumulator and the dual-shell gas storage unit are both connected to the inlet of the ejector. The outlet of the ejector is connected to the solar thermal accumulator. The outlets of the solar thermal accumulator and the second expander are both connected to the insulation gas channel. The hot side of the first accumulator and the second accumulator is located in the compressed air energy storage unit, and the cold side is located in the energy release unit.

[0009] Furthermore, the compressed air energy storage unit includes an electric motor, a first compressor, a first accumulator, a second compressor, a second electric motor, and a second accumulator. The hot-side outlet of the second accumulator is connected to the medium-pressure storage chamber of the double-shell air storage unit and the air inlet of the double-tank liquid piston unit.

[0010] Furthermore, the dual-tank liquid piston unit includes a first water-air tank, a second water-air tank, and a circulating water pump; the air inlets of the first and second water-air tanks are connected to each other and are equipped with air inlet valves respectively; the water outlet and water inlet of the first water-air tank are respectively connected to the water inlet and water outlet of the second water-air tank; valves are respectively installed at the water inlet and outlet of the first and second water-air tanks; a circulating water pump is installed on the water channel between the first and second water-air tanks; and pressure sensors are installed in both the first and second water-air tanks.

[0011] Furthermore, the double-shell gas storage unit is arranged from the inside out as follows: high-pressure gas storage chamber, high-pressure tank wall, medium-pressure gas storage chamber, medium-pressure tank wall, heat storage layer, heat insulation gas channel, and heat insulation layer. The double-shell gas storage unit is capsule-shaped. The high-pressure gas storage chamber is connected to the outside through the high-pressure gas channel, the medium-pressure gas storage chamber is connected to the outside through the medium-pressure gas channel, the inlet of the heat insulation gas channel is connected to the solar thermal accumulator, the first accumulator, the second accumulator, and the second expander, and the heat insulation gas channel is connected to the external atmospheric environment.

[0012] Furthermore, the heat-insulating gas channel is a curved channel, and the curved structure is achieved by the joint construction of the heat storage layer and the heat insulation layer. The heat storage layer is set close to the outer side of the intermediate pressure tank wall, and the hot side outlet of the second heat accumulator is connected to the high-pressure gas channel. The heat insulation layer is coated with an anti-corrosion coating.

[0013] Furthermore, the first inlet of the ejector is connected to the first accumulator, the second inlet of the ejector is connected to the medium-pressure gas channel of the double-shell gas storage unit, and the cold-side inlet of the second accumulator is connected to the high-pressure gas storage chamber of the double-shell gas storage unit.

[0014] Furthermore, the cold-side outlet of the first heat accumulator is connected to the ejector and the solar thermal heat accumulator via a first three-way valve; the ejector is connected to the first three-way valve via a second three-way valve.

[0015] The operation method of the solar-coupled double-shell near-isothermal compressed air energy storage system of the present invention involves the following steps during energy storage: air is compressed in the compressed air energy storage unit while releasing heat in the first and second accumulators. The compressed air first enters the medium-pressure storage chamber. After the air pressure in the medium-pressure storage chamber reaches a set value, the dual-tank liquid piston unit starts working. The compressed air enters the dual-tank liquid piston unit for further compression and then enters the high-pressure storage chamber. The energy storage process ends when the pressure in the high-pressure storage chamber reaches the set value.

[0016] Between energy storage and energy release, air is heated by the solar thermal accumulator, releases heat through the insulated air channel, and is then discharged.

[0017] During energy release, the high-pressure air in the high-pressure storage chamber enters the second accumulator to absorb heat and becomes high-temperature and high-pressure air, which then enters the first expander to do work. The air at the outlet of the first expander is heated by the first accumulator and the solar thermal accumulator before entering the second expander to do work. The exhaust heat of the second expander is released through the insulation gas channel and then discharged.

[0018] When insufficient sunlight or reduced heat in the accumulator during the later stages of energy storage causes a decrease in output power, the medium-pressure air in the medium-pressure storage chamber mixes with the air at the outlet of the first expander through the ejector and then enters the second expander through the solar thermal accumulator to perform work.

[0019] After energy release, the air is heated by the first and second accumulators and then enters the heat-insulating air channel to release heat to the heat storage layer.

[0020] During energy storage, when the dual-tank liquid piston unit starts working, the circulating water pump operates, and the first water-gas tank begins to receive water and compress gas. When the air pressure reaches the set value, air enters the high-pressure gas storage chamber through the high-pressure gas channel of the dual-shell gas storage unit. When the water level in the first water-gas tank reaches the set value, the second water-gas tank begins to receive water and compress gas. When the air pressure reaches the set value, air enters the high-pressure gas storage chamber through the high-pressure gas channel of the dual-shell gas storage unit. When the water level in the first water-gas tank reaches the set value, all valves are closed. During the exhaust process of the water-gas tanks in the dual-tank liquid piston unit, the gas exhaust flow rate is equal to the water pump flow rate.

[0021] Compared with the prior art, the present invention has at least the following beneficial effects:

[0022] This invention combines compressed air energy storage, a liquid piston and ejector, solar energy, and a double-shell gas storage system. During energy storage, the compressed air retains a certain temperature after passing through the heat accumulator. When the system releases energy, it utilizes the exhaust gas after energy release and the solar-heated air stored in the energy storage and release gap as insulation gas entering the insulation gas channel of the double-shell gas storage unit. The heat from the insulation unit is absorbed by the heat storage layer in the double-shell gas storage unit, thus insulating the air in the unit while rationally utilizing the waste heat from the exhaust gas after energy release, achieving energy cascade. The system effectively utilizes the heat stored in the solar thermal accumulator during the energy storage and release intervals, reducing heat loss during this period. A medium-pressure accumulator is located outside the high-pressure accumulator in the double-shell accumulator tank. The reduced pressure difference between the inside and outside of the high-pressure accumulator tank allows for a reduction in the tank's wall thickness, further improving the economic efficiency of the compressed air energy storage system. The air in the medium-pressure accumulator tank combines with the air from the first expander outlet via an ejector, further increasing the output power. This addresses the issue of reduced output power in the later stages of energy release due to decreased heat exchange in the accumulator and insufficient sunlight, thus improving the system's operational stability.

[0023] Furthermore, since the air pressure is lower than the storage pressure during energy release, and due to the existence of a heat exchange temperature difference, the accumulator still retains a certain amount of heat after energy release. This heat is used to heat the air, which then enters the double-shell storage unit and is absorbed by the heat storage layer through the insulation gas channel, preparing for the next energy storage process. Combined with the dual-tank liquid piston to achieve near-isothermal heat transfer, the system's energy storage efficiency is improved. From the perspectives of reducing heat generation and rationally utilizing the remaining heat in the accumulator, the energy in the energy storage system of this invention is utilized to the maximum extent, thereby improving the system's energy storage efficiency and energy storage density. Attached Figure Description

[0024] Figure 1 This invention relates to a double-shell near-isothermal compressed air energy storage system coupled with solar energy.

[0025] Figure 2 This is a cross-sectional view of the double-shell gas storage unit in this invention.

[0026] Figure 3 This is a three-dimensional view of the interior of the double-shell gas storage unit in this invention.

[0027] Figure 4 This is a three-dimensional view of the heat-insulating gas channel in the double-shell gas storage unit of the present invention.

[0028] Figure 5 This is a perspective view of the high-pressure gas storage chamber and some pipelines in the double-shell gas storage unit of the present invention.

[0029] Figure 6 This is a structural diagram of the heat storage layer in the double-shell gas storage unit of the present invention.

[0030] In the diagram: 1. First electric motor; 2. First compressor; 3. First heat accumulator; 4. Second compressor; 5. Second electric motor; 6. Second heat accumulator; 7. First intake valve; 8. Second intake valve; 9. First exhaust valve; 10. Second exhaust valve; 11. First water-gas tank; 12. Second water-gas tank; 13. First water inlet valve; 14. Second water inlet valve; 15. Circulating water pump; 16. First drain valve; 17. Second drain valve; 18. Double-shell gas storage unit; 19. First throttle valve; 20. Second throttle valve; 21. First expander; 22. First generator. 23. Motor; 24. First three-way valve; 25. Ejector; 26. Second three-way valve; 27. Photothermal accumulator; 28. Second expander; 29. ​​Second generator; 20. Medium-pressure inlet valve; 31. First pressure sensor; 32. Second pressure sensor; 183. Medium-pressure gas passage; 184. High-pressure gas passage; 185. Insulation layer; 186. Insulated gas passage; 187. Heat storage layer; 188. Medium-pressure gas storage chamber; 189. High-pressure gas storage chamber; 1810. Insulated gas inlet; 1811. Insulated gas outlet. Detailed Implementation

[0031] The invention will now be described in detail with reference to specific embodiments and accompanying drawings.

[0032] like Figure 1 As shown, a double-shell near-isothermal compressed air energy storage system coupled with solar energy includes a compressed air energy storage unit, a double-tank liquid piston unit, a double-shell gas storage unit, and an energy release unit; specifically, it includes a first motor 1, a first compressor 2, a first heat accumulator 3, a second compressor 4, a second motor 5, a second heat accumulator 6, a first intake valve 7, a second intake valve 8, a first exhaust valve 9, a second exhaust valve 10, a first water-gas tank 11, a second water-gas tank 12, a first water inlet valve 13, a second water inlet valve 14, a circulating water pump 15, a first drain valve 16, a second drain valve 17, a double-shell gas storage unit 18, and a second air release unit. 19. Throttling valve 1; 20. Second throttle valve 2; 21. First expander 2; 22. First generator 2; 23. First three-way valve 2; 24. Ejector 2; 25. Second three-way valve 2; 26. Photothermal accumulator 2; 27. Second expander 2; 28. Second generator 2; 29. ​​Medium-pressure inlet valve 2; 30. First pressure sensor 3; 31. Second pressure sensor 3; 181. Medium-pressure gas channel 1; 182. High-pressure gas channel 1; 183. Insulation layer 1; 184. Insulation gas channel 1; 185. Heat storage layer 1; 186. Medium-pressure tank wall 1; 187. Medium-pressure gas storage chamber 1; 188. High-pressure tank wall 1; 189. High-pressure gas storage chamber 1; 1810. Insulation gas inlet 1; 1811.

[0033] The compressed air energy storage unit includes an electric motor 1, a first compressor 2, a first accumulator 3, a second compressor 4, a second electric motor 5, a second accumulator 6, a medium-pressure intake valve 29, and a double-shell air storage unit 18 connected in sequence. The outlet of the first compressor 2 is connected to the hot side inlet of the first accumulator 3, the hot side outlet of the first accumulator 3 is connected to the inlet of the second compressor 4, the outlet of the second compressor 4 is connected to the hot side inlet of the second accumulator 6, and the hot side outlet of the second accumulator 6 is connected to the double-shell air storage unit 18 and the double-tank liquid piston unit.

[0034] The double-shell gas storage unit includes a medium-pressure gas channel 181, a high-pressure gas channel 182, an insulation layer 183, a heat-insulating gas channel 184, a heat storage layer 185, a medium-pressure tank wall 186, a medium-pressure gas storage chamber 187, a high-pressure tank wall 188, a high-pressure gas storage chamber 189, a heat-insulating gas inlet 1810, and a heat-insulating gas outlet 1811. From the inside out, the components are: high-pressure gas storage chamber 189, high-pressure tank wall 188, medium-pressure gas storage chamber 187, medium-pressure tank wall 186, heat storage layer 185, heat-insulating gas channel 184, and insulation layer 183. The double-shell gas storage unit is capsule-shaped. The high-pressure gas storage chamber 189 is connected to the outside through the high-pressure gas channel 182, and the medium-pressure gas storage chamber 187 is connected to the outside through the medium-pressure gas channel 181. The heat-insulating gas inlet 1810 connects to the solar thermal accumulator 26, the first accumulator 3, and the second accumulator. 6. The heat-insulating gas outlet 1811 is connected to the external atmospheric environment; the heat-insulating gas channel 184 connects the heat-insulating gas inlet 1810 and the heat-insulating gas outlet 1811. The heat-insulating gas channel 184 is a curved channel. The curved structure is achieved by the heat storage layer 185 and the insulation layer 183. The heat storage layer 185 is set close to the outer side of the medium-pressure tank wall 186. The hot side outlet of the second heat accumulator 6 is connected to the medium-pressure gas channel 181, and the cold side inlet of the second heat accumulator 6 is connected to the high-pressure gas channel 182.

[0035] The dual-tank liquid piston unit includes a first intake valve 7, a second intake valve 8, a first exhaust valve 9, a second exhaust valve 10, a first water-air tank 11, a second water-air tank 12, a first water inlet valve 13, a second water inlet valve 14, a circulating water pump 15, a first drain valve 16, a second drain valve 17, a first pressure sensor 30, and a second pressure sensor 31. The first exhaust valve 9 and the second exhaust valve 10 are connected to the high-pressure channel of the dual-shell gas storage unit 18, and the first intake valve 7 and the second intake valve 8 are connected to the second accumulator 6 of the compressed air energy storage unit. The first water-air tank... The air inlets of the first water-air tank 11 and the second water-air tank 12 are respectively provided with a first air inlet valve 7 and a second air inlet valve 8. The water inlets of the first water-air tank 11 and the second water-air tank 12 are respectively provided with a first water inlet valve 13 and a second water inlet valve 14. The water outlets of the first water-air tank 11 and the second water-air tank 12 are respectively provided with a first drain valve 16 and a second drain valve 17. A circulating water pump 15 is provided at the outlet of the first drain valve 16 and the second drain valve 17. A first pressure sensor 30 and a second pressure sensor 31 are respectively provided in the first water-air tank 11 and the second water-air tank 12.

[0036] The energy release unit includes a first throttle valve 19, a second heat accumulator 6, a first expander 21, a first generator 22, a first heat accumulator 3, a solar thermal heat accumulator 26, and a second expander 27 connected in sequence. It also includes an ejector 24, which is connected to the first heat accumulator 3 and the solar thermal heat accumulator 26 via a first three-way valve 23 and a second three-way valve 25, respectively. The first inlet of the ejector 24 is connected to the first heat accumulator 3, and the second inlet is connected to the medium-pressure gas passage 181 of the double-shell gas storage unit 18. The outlet of the second expander 27 is connected to the double-shell gas storage unit 18. The cold-side outlets of both the first heat accumulator 3 and the second heat accumulator 6 are connected to the double-shell gas storage unit 18. The cold-side inlet of the second heat accumulator 6 is also connected to the high-pressure gas passage 182 of the double-shell gas storage unit 18.

[0037] The insulation layer 183 in the double-shell gas storage unit is coated with a heat-insulating and anti-corrosion coating, and the various inlets and outlets in contact with other units have good sealing performance.

[0038] This invention discloses a double-shell near-isothermal compressed air energy storage system coupled with solar energy and its operation method. Details are as follows:

[0039] Before energy storage begins, the first water-gas tank 11 and the second water-gas tank 12 are filled with a set amount of water, and all valves are closed.

[0040] During energy storage, ambient air is compressed by the first compressor 2 and then enters the first heat accumulator 3 to release heat. It then enters the second compressor 4 and is compressed again before entering the second heat accumulator 6 to release heat. The medium-pressure inlet valve 29 outside the double-shell gas storage unit 18 opens. The compressed air first enters the medium-pressure gas storage chamber 187 through the medium-pressure inlet valve 29 and the medium-pressure air passage 181. Once the air pressure in the medium-pressure gas storage chamber 187 reaches the set value, the medium-pressure inlet valve 29 closes, the first water inlet valve 13 opens, the second drain valve 17 opens, the second air inlet valve 8 opens, and the circulating water pump 15 operates, causing the water level in the first water-air tank 11 to rise and the gas to be compressed. When the first pressure sensor 30 detects that the air pressure has reached the set value, the first exhaust valve 9 opens, and air passes through the high-pressure... Air enters the high-pressure gas storage chamber 189 through the air passage 182. When the water level in the first water-gas tank 11 reaches the set value, the first water inlet valve 13, the second drain valve 17, the second air inlet valve 8, and the first exhaust valve 9 are closed, while the second water inlet valve 14, the first drain valve 16, and the first air inlet valve 7 are opened. The water level in the second water-gas tank 12 rises. When the second pressure sensor 31 detects that the air pressure has reached the set value, the second exhaust valve 10 is opened, and air enters the high-pressure gas storage chamber 189 through the high-pressure air passage 182 of the double-shell gas storage unit 18. When the water level in the first water-gas tank 11 reaches the set value, all valves are closed. The above process is repeated until the pressure in the high-pressure gas storage chamber 189 reaches the set value, at which point the energy storage process ends. During the exhaust process of the water-gas tank, the gas exhaust flow rate is equal to the water pump flow rate.

[0041] Between energy storage and release, air is heated by the solar thermal accumulator 26, passes through the insulated air inlet 1810 and the insulated air channel 184, and is absorbed by the heat storage layer 185, reducing the heat loss of the air storage chamber and the solar thermal accumulator 26 between energy storage and release, and making full use of the sustainability of solar thermal energy.

[0042] When energy is released, the high-pressure air in the high-pressure storage chamber 189 is throttled through the first throttle valve 19 and enters the second heat accumulator 6, becoming high-temperature and high-pressure air. It then enters the first expander 21 to drive the first generator 22 to generate electricity. The a side of the first three-way valve 23 and the a side of the second three-way valve 25 are opened. The air at the outlet of the first expander 21 is heated by the first heat accumulator 3 and the solar thermal heat accumulator 26 and then enters the second expander 27 to drive the second generator 28 to generate electricity. The exhaust waste heat is absorbed by the heat storage layer 185 through the heat insulation gas inlet 1810 and the heat insulation gas channel 184.

[0043] When insufficient sunlight or reduced heat in the accumulator during the later stages of energy storage causes a decrease in output power, the b side of the first three-way valve 23 opens and the a side closes, the b side of the second three-way valve 25 opens and the a side closes. The medium-pressure air in the medium-pressure storage chamber 187 enters the ejector 24 through the second throttle valve 20 and mixes with the outlet air of the first expander 21. After mixing, the mixture enters the second expander 27 through the solar thermal accumulator 26, driving the second generator to generate electricity and improving the stability of the system operation.

[0044] After energy release, due to heat exchange and the fact that the air pressure is lower than the storage pressure during energy release, there is still some heat. The air is heated by the heat accumulator and then absorbed by the heat storage layer 185 through the heat insulation gas inlet 1810 and the heat insulation gas channel 184, and is further utilized.

[0045] Figure 2 This is a cross-sectional view of the double-shell gas storage unit in this invention. Figure 3 This is a three-dimensional view of the interior of the double-shell gas storage unit in this invention. Figure 4 This is a three-dimensional view of the heat-insulating gas channel in the double-shell gas storage unit of the present invention. Figure 5 This is a perspective view of the high-pressure gas storage chamber and some pipelines in the double-shell gas storage unit of the present invention. Figure 6 This is a structural diagram of the heat storage layer in the double-shell gas storage unit of the present invention.

[0046] In a preferred embodiment, the outer side of the heat-insulating gas channel 184 of the double-shell gas storage unit is an insulation layer 183 made of a material with good thermal insulation properties, and the inner side is a heat storage layer 185. The heat-insulating gas channel 184 is set as a corrugated shape to increase the contact area between the heat-insulating gas and the heat storage layer. The corrugated shape of the heat storage layer can increase the contact area between the heat-insulating gas and the heat storage layer, improve the residence time and disturbance degree of the heat-insulating gas in the heat-insulating gas channel 184, and enhance heat exchange.

[0047] The insulation layer 183 is coated with an anti-corrosion coating to prevent the gas storage tank from being corroded and oxidized.

[0048] The high-pressure gas channel 182 of the double-shell gas storage unit serves as the channel for high-pressure gas to enter and exit, and also serves to connect the high-pressure tank wall 188 and fix the high-pressure gas storage chamber 189. It is made of high-strength material. A medium-pressure gas storage chamber 187 is set outside the high-pressure gas storage chamber 189 of the double-shell gas storage unit. The medium-pressure tank wall and the high-pressure tank wall have good thermal conductivity.

[0049] In summary, the system described in this invention combines compressed air energy storage, a liquid piston and ejector, solar energy, and a double-shell gas storage unit. During energy storage, the compressed air still retains a certain amount of heat after passing through the accumulator. This heat, stored in the solar thermal accumulator and the waste heat from the expander exhaust during energy release, is stored through the energy storage and release gap. The remaining heat in the accumulator after energy release is absorbed by the heat storage layer of the double-shell gas storage unit. This not only keeps the air in the double-shell gas storage tank warm but also makes reasonable use of the waste heat from the exhaust after energy release, achieving cascaded energy utilization. Furthermore, it makes reasonable use of the heat stored in the solar thermal accumulator between the energy storage and release gaps, reducing heat loss from the accumulator during the process. The medium-pressure gas in the double-shell gas storage unit is combined with the outlet air of the first expander 21 via ejector 24, avoiding output instability caused by heat loss in the accumulator and insufficient solar radiation in the later stages of energy release. Combined with the dual-tank liquid piston, near-isothermal heat transfer is achieved, improving system efficiency. By reducing heat generation and rationally utilizing the remaining heat in the accumulator, the energy in this invention's energy storage system is maximized, improving system energy storage efficiency and density. The medium-pressure gas storage chamber reduces the pressure difference between the inside and outside of the high-pressure gas storage tank, reducing the wall thickness of the high-pressure gas storage tank and improving the system's economic efficiency.

Claims

1. A dual-shell near-isothermal compressed air energy storage system coupled with solar energy, characterized in that, The application relates to a compressed air energy storage unit, a double-tank liquid piston unit and a release unit; the compressed air energy storage unit is provided with a double-shell type gas storage unit (18), the double-shell type gas storage unit (18) is provided with a high-pressure gas storage chamber (189) and a medium-pressure gas storage chamber (187) in a nested mode, the outer side of the medium-pressure gas storage chamber (187) is provided with a heat preservation gas channel (184), the gas outlet of the compressed air energy storage unit is connected with the gas inlet of the double-tank liquid piston unit and the medium-pressure gas storage chamber (187) of the double-shell type gas storage unit, the gas outlet of the double-tank liquid piston unit is connected with the high-pressure gas storage chamber (189) of the double-shell type gas storage unit, the release unit comprises a second heat accumulator (6), a first expander (21), a first heat accumulator (3), a light-heat heat accumulator (26) and a second expander (27) which are sequentially connected; the gas inlets of the first heat accumulator (3) and the double-shell type gas storage unit (18) are connected with the gas inlet of an ejector (24), the gas outlet of the ejector (24) is connected with the light-heat heat accumulator (26), and the gas outlets of the light-heat heat accumulator (26) and the second expander (27) are connected with the heat preservation gas channel (184); the hot sides of the first heat accumulator (3) and the second heat accumulator (6) are arranged in the compressed air energy storage unit, and the cold sides are arranged in the release unit; the double-shell type gas storage unit (18) is provided with the high-pressure gas storage chamber (189), a high-pressure tank wall (188), the medium-pressure gas storage chamber (187), a medium-pressure tank wall (186), a heat storage layer (185), the heat preservation gas channel (184) and a heat insulation layer (183) in a sequence from inside to outside; the double-shell type gas storage unit (18) is in a capsule shape, the high-pressure gas storage chamber (189) is connected with the outside through a high-pressure gas channel (182), the medium-pressure gas storage chamber (187) is connected with the outside through a medium-pressure gas channel (181), the heat preservation gas channel (184) is connected with the light-heat heat accumulator (26), the first heat accumulator (3), the second heat accumulator (6) and the second expander (27), and the heat preservation gas channel (184) is connected with the outside atmosphere; the heat preservation gas channel (184) is a curved surface type channel, the curved surface structure of the curved surface type channel is realized through the heat storage layer (185) and the heat insulation layer (183), the heat storage layer (185) is arranged on the outer side of the medium-pressure tank wall (186), the cold side inlet of the second heat accumulator (6) is connected with the high-pressure gas channel (182), and the outer side of the heat insulation layer (183) is coated with a corrosion-proof coating.

2. The dual shell near-isothermal compressed air energy storage system coupled with solar energy of claim 1, wherein, The compressed air energy storage unit comprises a motor (1), a first compressor (2), a first heat accumulator (3), a second compressor (4), a second motor (5) and a second heat accumulator (6), and the hot side outlet of the second heat accumulator (6) is connected with the medium-pressure gas storage chamber (187) of the double-shell type gas storage unit (18) and the gas inlet of the double-tank liquid piston unit.

3. The dual shell near-isothermal compressed air energy storage system coupled with solar energy of claim 1, wherein, The double-tank liquid piston unit comprises a first water gas tank (11), a second water gas tank (12) and a circulating water pump (15); the air inlets of the first water gas tank (11) and the second water gas tank (12) are connected to each other and are respectively provided with air inlet valves; the water outlet of the first water gas tank (11) and the water inlet of the second water gas tank (12) are respectively connected to the water inlet and the water outlet of the second water gas tank (12); the water inlets and the water outlets of the first water gas tank (11) and the second water gas tank (12) are respectively provided with valves; the circulating water pump (15) is arranged on the water channel between the first water gas tank (11) and the second water gas tank (12); and the first water gas tank (11) and the second water gas tank (12) are respectively provided with pressure sensors.

4. The dual shell near-isothermal compressed air energy storage system coupled with solar energy of claim 1, wherein, The first inlet of the ejector (24) is connected to the first heat accumulator (3), the second inlet of the ejector (24) is connected to the medium-pressure gas channel (181) of the double-shell gas storage unit (18), and the cold side inlet of the second heat accumulator (6) is communicated with the high-pressure gas storage chamber (189) of the double-shell gas storage unit (18).

5. The dual shell near-isothermal compressed air energy storage system coupled with solar energy of claim 1, wherein, The cold side outlet of the first heat accumulator (3) is connected to the ejector (24) and the light-heat heat accumulator (26) through the first three-way valve (23); and the second three-way valve (25) is communicated with the ejector (24) and the first three-way valve (23).

6. The operation method of the solar coupled double-shell near-isothermal compressed air energy storage system according to any one of claims 1-5, characterized in that, During energy storage, air is compressed in the compressed air energy storage unit and at the same time releases heat in the first heat accumulator (3) and the second heat accumulator (6); the compressed air first enters the medium-pressure gas storage chamber (187), and when the air pressure in the medium-pressure gas storage chamber (187) reaches a set value, the double-tank liquid piston unit starts to work, the compressed air enters the double-tank liquid piston unit for further compression and then enters the high-pressure gas storage chamber (189), and when the pressure of the high-pressure gas storage chamber (189) reaches a set value, the energy storage process ends; During the energy storage and release gap, air is heated by the light-heat heat accumulator (26) and then discharged after releasing heat through the heat preservation gas channel (184); During energy release, high-pressure air in the high-pressure gas storage chamber (189) enters the second heat accumulator (6) to become high-temperature and high-pressure air, and then enters the first expander (21) to do work; the outlet air of the first expander (21) is heated by the first heat accumulator (3) and the light-heat heat accumulator (26) and then enters the second expander (27) to do work; the exhaust heat of the second expander (27) is released through the heat preservation gas channel (184) and then discharged; When the output power is reduced due to insufficient light and reduced heat in the first heat accumulator (3), the second heat accumulator (6) and the light-heat heat accumulator (26) after energy storage, the medium-pressure air in the medium-pressure gas storage chamber (187) enters the ejector (24) to mix with the outlet air of the first expander (21), and then enters the second expander (27) to do work through the light-heat heat accumulator (26).

7. The method of operation of claim 6, wherein, After energy release, air is heated by the first heat accumulator (3) and the second heat accumulator (6) and then enters the heat preservation gas channel (184) to release heat to the heat storage layer (185).

8. The method of operating of claim 6, wherein, The double-tank liquid piston unit comprises a first water gas tank (11), a second water gas tank (12) and a circulating water pump (15); the air inlets of the first water gas tank (11) and the second water gas tank (12) are connected with each other and are respectively provided with air inlet valves; the water outlet of the first water gas tank (11) and the water inlet of the second water gas tank (12) are respectively connected with the water inlet of the second water gas tank (12) and the water outlet of the first water gas tank (11); the water inlets and the water outlets of the first water gas tank (11) and the second water gas tank (12) are respectively provided with valves; the circulating water pump (15) is arranged on the water channel between the first water gas tank (11) and the second water gas tank (12); the first water gas tank (11) and the second water gas tank (12) are respectively provided with pressure sensors; during the energy storage process, when the double-tank liquid piston unit starts to work, the circulating water pump (15) works, the first water gas tank (11) starts to fill water to compress gas, when the air pressure reaches a set value, the air enters a high-pressure gas storage chamber (189) through a high-pressure gas channel (182) of a double-shell gas storage unit (18), when the water level of the first water gas tank (11) reaches a set value, the second water gas tank (12) starts to fill water to compress gas, when the air pressure reaches a set value, the air enters the high-pressure gas storage chamber (189) through the high-pressure gas channel (182) of the double-shell gas storage unit (18), when the water level of the first water gas tank (11) reaches a set value, all the valves are closed, and during the exhaust process of the first water gas tank (11) and the second water gas tank (12) of the double-tank liquid piston unit, the gas exhaust flow is equal to the circulating water pump (15) flow.

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