A near-isothermal compressed air energy storage device and method

Abstract

The present invention discloses a near-isothermal compressed air energy storage device and method, comprising a first hydraulic cylinder, a second hydraulic cylinder, a first vent valve, a first drain valve, a first pump group water inlet valve, a first pump group drain valve, a second water inlet valve, a pump group, a high-pressure gas tank, a first pipeline, a second high-pressure exhaust pipe, and a second high-pressure exhaust valve. The first hydraulic cylinder and the second hydraulic cylinder are connected via a first pipeline, one end of the first pipeline is connected to the bottom of the first hydraulic cylinder, and the other end of the first pipeline is connected to the second hydraulic cylinder. The volume of the first hydraulic cylinder is the same as that of the second hydraulic cylinder. The first drain valve, the first pump group water inlet valve, the pump group, the first pump group drain valve, and the second water inlet valve are sequentially connected to the first pipeline, and the pump group includes several water pumps connected in series. The second hydraulic cylinder and the high-pressure gas tank are connected via a second high-pressure exhaust pipe, and the second high-pressure exhaust valve is disposed on the second high-pressure exhaust pipe. This promotes isothermal compression / expansion and improves system circulation efficiency.

Description

Technical Field

[0001] The present invention relates to the field of gas compression and expansion, and in particular to a near-isothermal compressed air energy storage device and method. Background Art

[0002] Compressed air energy storage technology has broad application prospects in wind and solar power grid integration, peak load regulation, and carbon emission reduction. Its principle is to compress air using off-peak electricity, wind power, photovoltaic power, and other sources, converting electrical energy into stored air pressure energy. During energy release, the stored compressed air drives a turbine to generate electricity. Isothermal compressed air energy storage systems employ a series of technical measures to achieve near-isothermal compression and expansion processes, minimizing the system's compression temperature rise and expansion temperature drop. This significantly improves energy efficiency, offering excellent energy storage performance and broad development prospects.

[0003] Existing isothermal compressed air energy storage technology utilizes multi-cylinder circulation, liquid pistons, and spray technologies to facilitate isothermal compression and expansion. However, at the end of compression and the beginning of expansion, the pressure ratio changes very quickly, resulting in significant temperature changes. However, the spray coverage area is small, and the gas-liquid contact heat transfer area is constant, resulting in poor isothermal results during the actual compression and expansion process. Furthermore, due to the large pressure variations during compression and expansion, the ratio of high to low pressure can reach hundreds, and the operating pressures of the pumps and turbines deviate significantly from their designed operating conditions, resulting in actual storage / release cycle efficiencies far below those of an ideal isothermal cycle. These factors have hindered the development and promotion of isothermal compressed air energy storage technology. Further promoting isothermal compression / expansion and improving system cycle efficiency are key to its further promotion and application. Summary of the Invention

[0004] The technical problem to be solved by the present invention is to address the deficiencies of the above-mentioned prior art and provide a near-isothermal compressed air energy storage device and method, which utilizes the large specific heat capacity of liquid to reduce the temperature variation of the gas through gas-liquid heat exchange.

[0005] In order to solve the above technical problems, the technical solution adopted by the present invention is:

[0006] A near-isothermal compressed air energy storage device comprises a first hydraulic cylinder, a second hydraulic cylinder, a first vent valve, a first drain valve, a first pump group water inlet valve, a first pump group drain valve, a second water inlet valve, a pump group, a high-pressure gas tank, a first pipeline, a second high-pressure exhaust pipe, and a second high-pressure exhaust valve; the first hydraulic cylinder and the second hydraulic cylinder are connected through a first pipeline, one end of the first pipeline is connected to the bottom of the first hydraulic cylinder, and the other end of the first pipeline is connected to the second hydraulic cylinder, and the volume of the first hydraulic cylinder is the same as that of the second hydraulic cylinder; the first vent valve is arranged at the top of the first hydraulic cylinder, the first drain valve, the first pump group water inlet valve, the pump group, the first pump group drain valve, and the second water inlet valve are connected to the first pipeline in sequence, and the pump group includes a plurality of water pumps connected in series; the second high-pressure exhaust pipe is arranged at the top of the second hydraulic cylinder, the second hydraulic cylinder and the high-pressure gas tank are connected through the second high-pressure exhaust pipe, and the second high-pressure exhaust valve is arranged on the second high-pressure exhaust pipe.

[0007] As a further preferred embodiment of the present invention, it also includes a second pipeline, a second vent valve, a first water inlet valve, a second drain valve, a second pump group water inlet valve, a second pump group drain valve, a first high-pressure exhaust pipe and a first high-pressure exhaust valve; the first hydraulic cylinder and the second hydraulic cylinder are connected through a second pipeline, one end of the second pipeline is connected to the bottom of the second hydraulic cylinder, and the other end of the second pipeline is connected to the first hydraulic cylinder; the second vent valve is arranged at the top of the second hydraulic cylinder, and the first water inlet valve, the second pump group drain valve, the pump group, the second pump group water inlet valve and the second drain valve are connected to the second pipeline in sequence; the first high-pressure exhaust pipe is arranged at the top of the first hydraulic cylinder, the first hydraulic cylinder and the high-pressure gas tank are connected through the first high-pressure exhaust pipe, and the first high-pressure exhaust valve is arranged on the first high-pressure exhaust pipe.

[0008] As a further preference of the present invention, it also includes a first porous plate and a second porous plate, the first porous plate is mounted on the inner wall of the first hydraulic cylinder, and the vertical height of one end of the second pipe extending into the first hydraulic cylinder is greater than the vertical height of the first porous plate; the second porous plate is mounted on the inner wall of the second hydraulic cylinder, and the vertical height of one end of the first pipe extending into the second hydraulic cylinder is greater than the vertical height of the second porous plate.

[0009] As a further preferred embodiment of the present invention, the cross-sections of the first hydraulic cylinder and the second hydraulic cylinder are both variable cross-section structures, and as the heights of the first hydraulic cylinder and the second hydraulic cylinder increase, the cross-sectional areas of the first hydraulic cylinder and the second hydraulic cylinder increase.

[0010] As a further preference of the present invention, it also includes a pump group water exchange inlet pipe, a pump group water exchange drain pipe, a pump group water exchange inlet valve and a pump group water exchange drain valve. The pump group water exchange inlet pipe is connected to the water inlet end of the pump group, the pump group water exchange drain pipe is connected to the drain end of the pump group, the pump group water exchange inlet valve is arranged on the pump group water exchange inlet pipe, and the pump group water exchange drain valve is arranged on the pump group water exchange drain pipe.

[0011] As a further preference of the present invention, it also includes a gas expansion power generation device, which includes a third hydraulic cylinder, a first high-pressure air intake pipe, a first high-pressure air intake valve, a first wheel group water inlet valve, a first wheel group drain valve, a fourth vent valve, a third pipeline, a wheel group and a fourth hydraulic cylinder; the first high-pressure air intake pipe is arranged at the top of the third hydraulic cylinder, the third hydraulic cylinder is connected to the high-pressure gas tank through the first high-pressure air intake pipe, and the first high-pressure air intake valve is arranged on the first high-pressure air intake pipe; the fourth vent valve is arranged at the top of the fourth hydraulic cylinder, the third hydraulic cylinder is connected to the fourth hydraulic cylinder through the third pipeline, the first wheel group drain valve, the wheel group and the first wheel group water inlet valve are connected to the third pipeline in sequence, the wheel group includes several turbines in series, and the volume of the third hydraulic cylinder is the same as that of the fourth hydraulic cylinder.

[0012] As a further preference of the present invention, the gas expansion device also includes a second high-pressure air intake pipe, a third vent valve, a second high-pressure air intake valve, a second wheel group water inlet valve, a second wheel group drain valve and a fourth pipeline. The second high-pressure air intake pipe is arranged at the top of the fourth hydraulic cylinder, the fourth hydraulic cylinder is connected to the high-pressure gas tank through the second high-pressure air intake pipe, the second high-pressure air intake valve is arranged on the second high-pressure air intake pipe, the third vent valve is arranged on the top of the third hydraulic cylinder, the third hydraulic cylinder and the fourth hydraulic cylinder are connected through the fourth pipeline, the second wheel group water inlet valve, the wheel group and the second wheel group drain valve are connected to the fourth pipeline in sequence.

[0013] As a further preference of the present invention, it also includes a first high-pressure mist pump, a second high-pressure mist pump, a first fog pump pipe, a second fog pump pipe, a first spray valve, a second spray valve, a first nozzle and a second nozzle; both ends of the first fog pump pipe are arranged in the third hydraulic cylinder, both ends of the second fog pump pipe are arranged in the fourth hydraulic cylinder, the first high-pressure mist pump and the first spray valve are connected to the first fog pump pipe, a plurality of first nozzles are arranged at the top of the third hydraulic cylinder and connected to one end of the first fog pump pipe, the second high-pressure mist pump and the second spray valve are connected to the second fog pump pipe, and a plurality of second nozzles are arranged at the top of the fourth hydraulic cylinder and connected to one end of the second fog pump pipe.

[0014] As a further preferred embodiment of the present invention, the third hydraulic cylinder and the fourth hydraulic cylinder are both variable cross-section structures, and as the heights of the third hydraulic cylinder and the fourth hydraulic cylinder decrease, the cross-sectional areas of the third hydraulic cylinder and the fourth hydraulic cylinder increase.

[0015] A near-isothermal compressed air energy storage method, step (1), second hydraulic cylinder compressed air energy storage: first, the first hydraulic cylinder is filled with liquid, and when the air in the second hydraulic cylinder is compressed, the first ventilation valve, the first drainage valve, the first pump group water inlet valve, the first pump group drainage valve and the second water inlet valve are opened, and the other valves are closed; the pump group is running, and since the first hydraulic cylinder is connected to the atmosphere, different numbers of water pumps running in series are selected according to the real-time pressure size in the second hydraulic cylinder to pump the liquid from the first hydraulic cylinder into the second hydraulic cylinder; as the liquid level in the second hydraulic cylinder rises, the volume occupied by the air in the second hydraulic cylinder decreases and is compressed, and the compressed gas and liquid undergo gas-liquid heat transfer at the gas-liquid interface, and the liquid absorbs the compression heat to reduce the temperature of the compressed gas; and the water flowing into the second hydraulic cylinder passes through the first hydraulic cylinder. The porous plate in the second hydraulic cylinder is divided into multiple streams through the holes and falls into the lower part of the second hydraulic cylinder. During the falling process, the compressed gas is fully mixed and heat-exchanged, further reducing the temperature of the compressed gas. As the liquid level rises, the compression ratio of the gas becomes larger and larger, and the gas temperature becomes higher and higher. At this time, the cross-sectional area of the second hydraulic cylinder increases with the increase of the liquid level, the contact area between the gas and the liquid surface increases, and the heat exchange capacity is further enhanced. The above cooling measures make the gas compression process closer to an isothermal process. When the compressed gas in the second hydraulic cylinder reaches a certain pressure, the second high-pressure exhaust valve is opened, and the high-pressure gas is discharged into the high-pressure gas tank. The pump group continues to run until the liquid level fills the hydraulic cylinder and the gas in the second hydraulic cylinder is completely compressed into the high-pressure gas tank. The second high-pressure exhaust valve is closed, and the gas compression process in the second hydraulic cylinder is completed.

[0016] Step (2), the first hydraulic cylinder compresses gas to store energy: open the first water inlet valve, the second ventilation valve and the second drainage valve, the second pump group water inlet valve and the second pump group drainage valve, and close the other valves; the same as the energy storage principle of the step, so that continuous gas compression is achieved by alternating the operation of the first hydraulic cylinder and the second hydraulic cylinder; step (3), the third hydraulic cylinder gas expansion generates electricity: the third hydraulic cylinder is filled with liquid, open: the third high-pressure air inlet valve, the first high-pressure air inlet valve, the first wheel group water inlet valve, the first spray valve, the first wheel group drainage valve and the fourth ventilation valve, and close the other valves; run the first high-pressure mist pump, the high-pressure gas expands to make the liquid in the third hydraulic cylinder have a higher water head, The high-head liquid impacts the wheel group to generate electricity. At the same time, the operating first high-pressure mist pump sprays the liquid in the third hydraulic cylinder through the first mist pump pipe and the first nozzle arranged on the top of the third hydraulic cylinder in the form of mist, covering the expansion space in the third hydraulic cylinder over a large area. The mist droplets contact the expansion gas during the falling process, release heat to the expansion gas, further reduce the temperature drop of the expansion gas, and the mist droplets finally fall into the liquid; until the liquid level in the third hydraulic cylinder drops to a certain height, the high-pressure gas expands and drives the liquid in the third hydraulic cylinder to pass through the wheel group to end the power generation; step (4), the fourth hydraulic cylinder gas expands to generate electricity: at this time, the hydraulic cylinder is full of liquid, the second high-pressure mist pump, the second spray valve, the second high-pressure gas valve, the third vent valve, the second wheel group water inlet valve, the second wheel group drain valve are opened, and the other valves are closed. The power generation principle is the same as step (3), so that the high-pressure gas drives the liquid in the second hydraulic cylinder to pass through the wheel group to generate electricity, until the liquid level in the fourth hydraulic cylinder drops to a certain height, the high-pressure gas expands and drives the liquid in the second hydraulic cylinder to pass through the wheel group to end the power generation, so that continuous power generation is achieved by alternating expansion of high-pressure gas in the third hydraulic cylinder and the fourth hydraulic cylinder.

[0017] The present invention has the following beneficial effects:

[0018] 1. Variable-section hydraulic cylinder: Enhanced heat exchange on the gas-liquid interface: During compression, as the liquid level in the hydraulic cylinder rises, the gas temperature increases, and the gas-liquid temperature difference increases. At this time, the gas-liquid contact heat exchange area increases, enhancing heat exchange; during expansion, as the liquid level in the hydraulic cylinder drops, the gas temperature decreases, and the liquid-gas temperature difference increases. At this time, the gas-liquid contact heat exchange area increases, enhancing heat exchange;

[0019] 2. During compression, the water inlet outlet of the hydraulic cylinder is set at the upper part of the hydraulic cylinder, so that the water flow drawn into the hydraulic cylinder passes through the porous plate inside the cylinder and turns into multiple streams that fall into the lower part of the hydraulic cylinder. During the falling process, the water is fully mixed with the compressed gas and heat is exchanged, further reducing the temperature of the compressed gas. During expansion, multiple nozzles are set at the top of the hydraulic cylinder to increase the coverage of the droplets and enhance the heat exchange of the gas-mist mixture.

[0020] 3. During compression, the water inlet pipe of the hydraulic cylinder is arranged inside the hydraulic cylinder, avoiding the need to consider the high pressure resistance of the pipe when the water inlet pipe is placed outside; during expansion, the mist pump pipe of the high-pressure mist pump is arranged inside the hydraulic cylinder, reducing the pressure resistance requirement of the mist pump pipe;

[0021] 4. Use multi-stage pump groups and turbine groups: During compression, different numbers of high-pressure water pumps are connected in series according to the pressure changes of the compressed gas to prevent a single-stage water pump from failing to reach the target pressure; during expansion, different numbers of turbines are connected in series under variable water heads to fully utilize the power generation potential of the water head. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Figure 1 It is a schematic diagram of the overall structure of the present invention;

[0023] Figure 2 is a schematic diagram of compressing the air in the second hydraulic cylinder according to the present invention;

[0024] Figure 3 is a schematic diagram of compressing the air in the first hydraulic cylinder according to the present invention;

[0025] Figure 4 is a schematic diagram of the high-pressure gas of the present invention expanding in the third hydraulic cylinder to generate electricity;

[0026] Figure 5 It is a schematic diagram of the high-pressure gas of the present invention expanding in the fourth hydraulic cylinder to generate electricity.

[0027] The components include: 1. first hydraulic cylinder, 12. water inlet end of second pipe, 13. first porous plate, 14. first vent valve, 15. first high-pressure exhaust valve, 16. first drain valve, 17. first water inlet valve;

[0028] 2. Second hydraulic cylinder, 22. Water inlet end of first pipeline, 23. Second porous plate, 24. Second vent valve, 25. Second high-pressure exhaust valve, 26. Second drain valve, 27. Second water inlet valve;

[0029] 31. Second pump group inlet valve, 32. Pump group, 33. Pump group series valve, 34. Pump group drain valve, 35. First pump group drain valve, 36. Second pump group drain valve, 37. First pump group inlet valve, 38 Pump group water change inlet valve, 39 Pump group water change drain valve;

[0030] 4. High-pressure gas tank;

[0031] 5. Third hydraulic cylinder, 52. First mist pump pipe, 53. Third ventilation valve, 54. First high-pressure mist pump, 55. First nozzle, 56. First spray valve, 57. First high-pressure air inlet valve;

[0032] 6. Fourth hydraulic cylinder, 62. Second mist pump pipe, 63. Fourth ventilation valve, 64. Second high-pressure mist pump, 65. Second nozzle, 66. Second spray valve, 67. Second high-pressure air inlet valve;

[0033] 71. First wheel group water inlet valve, 72 wheel group, 73 wheel group series valve, 74 wheel group drain valve, 75 second wheel group drain valve, 76. First wheel group drain valve, 77. Second wheel group water inlet valve, 78 wheel group water change switching valve;

[0034] 81. Third pipeline, 82. Fourth pipeline, 83. First high-pressure exhaust pipe, 84. Second high-pressure exhaust pipe, 85. First high-pressure intake pipe, 88. Second high-pressure intake pipe. DETAILED DESCRIPTION

[0035] The present invention will be further described in detail below with reference to the accompanying drawings and specific preferred embodiments.

[0036] In the description of the present invention, it should be understood that the terms "left side," "right side," "upper," "lower," etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings and are intended solely to facilitate the description of the present invention and simplify the description. They do not indicate or imply that the devices or components referred to must have a specific orientation, be constructed, or operate in a specific orientation. Terms such as "first" and "second" do not indicate the importance of components and therefore should not be construed as limiting the present invention. The specific dimensions used in this embodiment are intended to illustrate the technical solution and do not limit the scope of protection of the present invention.

[0037] like Figure 1-5As shown, a nearly isothermal compressed air energy storage device includes a first hydraulic cylinder 1, a second hydraulic cylinder 2, a first vent valve 14, a first drain valve 16, a first pump group water inlet valve 37, a first pump group drain valve 35, a second water inlet valve 27, a pump group 32, a high-pressure gas tank 4, a first pipe 81, a second high-pressure exhaust pipe 86 and a second high-pressure exhaust valve 25; the first hydraulic cylinder 1 and the second hydraulic cylinder 2 are connected through the first pipe 81, one end of the first pipe 81 is connected to the bottom of the first hydraulic cylinder 1, and the other end of the first pipe 81 is connected to the second hydraulic cylinder 2, and the volume of the first hydraulic cylinder 1 is equal to that of the second hydraulic cylinder 2. The first hydraulic cylinder 1 has the same volume; the first vent valve 14 is located at the top of the first hydraulic cylinder 1. The first drain valve 16, the first pump group water inlet valve 37, the pump group 32, the first pump group drain valve 35, and the second pump group water inlet valve 27 are sequentially connected to the first pipe 81. The pump group 32 includes several water pumps connected in series. A second high-pressure exhaust pipe 86 is located at the top of the second hydraulic cylinder 2. The second hydraulic cylinder 2 and the high-pressure gas tank 4 are connected via the second high-pressure exhaust pipe 86. The second high-pressure exhaust valve 25 is located on the second high-pressure exhaust pipe 86. The first hydraulic cylinder 1 is filled with liquid, and the pump group 32 pumps the liquid from the first hydraulic cylinder 1 into the second hydraulic cylinder 2. Because the first hydraulic cylinder 1 is connected to the atmosphere, the number of water pumps running in series can be selected based on the actual pressure in the second hydraulic cylinder 2. This is achieved by adjusting the pump group series valve 33 and the pump group drain valve 34. As the liquid level in the second hydraulic cylinder 2 rises, the volume of air in the second hydraulic cylinder 2 decreases and is compressed. The compressed gas and liquid undergo heat transfer at the gas-liquid interface, and the liquid absorbs the heat of compression, lowering the temperature of the compressed gas.

[0038] When the compressed gas in the second hydraulic cylinder 2 reaches a certain pressure, the second high-pressure exhaust valve 25 is opened, and the high-pressure gas is discharged into the high-pressure gas tank 4. The pump group 32 continues to operate until the liquid level fills the second hydraulic cylinder 2. The gas in the second hydraulic cylinder 2 is completely compressed into the high-pressure gas tank 2. The second high-pressure exhaust valve 25 is closed, and the gas compression process in the second hydraulic cylinder 2 is completed.

[0039] The system also includes a second pipe 82, a second vent valve 24, a first water inlet valve 17, a second drain valve 26, a second pump group water inlet valve 31, a second pump group drain valve 36, a first high-pressure exhaust pipe 85, and a first high-pressure exhaust valve 15. The first hydraulic cylinder 1 and the second hydraulic cylinder 2 are connected via the second pipe 82, one end of which is connected to the bottom of the second hydraulic cylinder 2, and the other end of which is connected to the first hydraulic cylinder 1. The second vent valve 24 is located at the top of the second hydraulic cylinder 2. The first water inlet valve 17, the second pump group drain valve 36, the pump group 32, the second pump group water inlet valve 31, and the second drain valve 26 are sequentially connected to the second pipe 82. The first high-pressure exhaust pipe 85 is located at the top of the first hydraulic cylinder 1. The first hydraulic cylinder 1 and the high-pressure gas tank 4 are connected via the first high-pressure exhaust pipe 85. The first high-pressure exhaust valve 15 is located on the first high-pressure exhaust pipe 85. At this point, the second hydraulic cylinder 2 is filled with liquid, while the first hydraulic cylinder 1 is filled with air at standard atmospheric pressure. The gas in the first hydraulic cylinder 1 is compressed by switching the valves. The pump group 32 pumps the liquid in the second hydraulic cylinder 2 into the first hydraulic cylinder 1 to compress the gas in the first hydraulic cylinder 1. Similar to the above-mentioned compression process of the gas in the second hydraulic cylinder 2, the gas compression process in the first hydraulic cylinder 1 tends to be isothermal through gas-liquid contact, gas-liquid mixing and increasing the gas-liquid contact surface.

[0040] When the gas in the first hydraulic cylinder 1 reaches a certain pressure, the first high-pressure exhaust valve 15 opens, and the high-pressure gas is discharged into the high-pressure gas tank 4. At the same time, the pump group 32 continues to operate until the liquid level fills the first hydraulic cylinder 1, and the gas in the first hydraulic cylinder 1 is completely compressed into the high-pressure gas tank 4. The first high-pressure exhaust valve 15 is closed, and the gas compression process in the first hydraulic cylinder 1 is completed. The first hydraulic cylinder 1 is filled with liquid, and the second hydraulic cylinder 2 is filled with air at standard atmospheric pressure. The gas in the second hydraulic cylinder 2 is further compressed by switching the valves. In this way, continuous gas compression is achieved by alternating the operation of the first and second hydraulic cylinders 1 and 2.

[0041] The system further includes a pump unit water exchange inlet pipe, a pump unit water exchange outlet pipe, a pump unit water exchange inlet valve 38, and a pump unit water exchange outlet valve 39. The pump unit water exchange inlet pipe is connected to the water inlet end of the pump unit 32, and the pump unit water exchange outlet pipe is connected to the outlet end of the pump unit 32. The pump unit water exchange inlet valve 38 is arranged on the pump unit water exchange inlet pipe, and the pump unit water exchange outlet valve 39 is arranged on the pump unit water exchange outlet pipe. When the temperature of the liquid in the first hydraulic cylinder 1 or the second hydraulic cylinder 2 is high and the cooling effect is poor, the liquid in the first hydraulic cylinder 1 or the second hydraulic cylinder 2 can be replaced through the pump unit water exchange inlet valve 38 and the pump unit water exchange outlet valve 39.

[0042] The system further includes a first porous plate 13 and a second porous plate 23. The first porous plate 13 is mounted on the inner wall of the first hydraulic cylinder 1, and the vertical height of the end of the second pipe 82 extending into the first hydraulic cylinder 1 is greater than the vertical height of the first porous plate 13. The second porous plate 23 is mounted on the inner wall of the second hydraulic cylinder 2, and the vertical height of the end of the first pipe 81 extending into the second hydraulic cylinder 2 is greater than the vertical height of the second porous plate 23. The water outlet end 22 of the first pipe is located above the second porous plate 23, so that the water drawn into the second hydraulic cylinder 2 passes through the second porous plate 23 in the cylinder, and the water is divided through the holes into multiple thin streams that fall into the lower part of the second hydraulic cylinder 2. During the falling process, the water is fully mixed with the compressed gas and exchanges heat, further reducing the temperature of the compressed gas. The water inlet end 12 of the second pipe is arranged at the upper part of the first porous plate 13, so that the water flow drawn into the first hydraulic cylinder 1 passes through the first porous plate 13 in the cylinder, and is divided into multiple streams through the holes and falls into the lower part of the first hydraulic cylinder 1. During the falling process, the water is fully mixed with the compressed gas and heat is exchanged, thereby further reducing the temperature of the compressed gas.

[0043] The cross-sections of the first and second hydraulic cylinders 1 and 2 are both variable-section structures. As the height of the first and second hydraulic cylinders 1 and 2 increases, the cross-sectional area of the first and second hydraulic cylinders 1 and 2 increases. As the liquid level rises, the gas compression ratio increases, and the gas temperature increases. At this point, the cross-sectional area of the first and second hydraulic cylinders 1 and 2 increases with the liquid level, increasing the gas-liquid contact area and further enhancing the heat exchange capacity. These three cooling measures make the gas compression process more closely resemble an isothermal process.

[0044] The system also includes a gas expansion power generation device, which includes a third hydraulic cylinder 5, a first high-pressure air intake pipe 87, a first high-pressure air intake valve 57, a first wheel assembly water inlet valve 71, a first wheel assembly water discharge valve 76, a fourth vent valve 63, a third pipeline 83, a wheel assembly 72, and a fourth hydraulic cylinder 6. The first high-pressure air intake pipe 87 is located at the top of the third hydraulic cylinder 5, connecting the third hydraulic cylinder 5 to the high-pressure gas tank 4 via the first high-pressure air intake pipe 87. The first high-pressure air intake valve 57 is located on the first high-pressure air intake pipe 87. The fourth vent valve 63 is located at the top of the fourth hydraulic cylinder 6, connecting the third hydraulic cylinder 5 and the fourth hydraulic cylinder 6 via the third pipeline 83. The first wheel assembly water discharge valve 76, the wheel assembly 72, and the first wheel assembly water inlet valve 71 are sequentially connected to the third pipeline 83. The wheel assembly 72 includes several turbines connected in series. The volume of the third hydraulic cylinder 5 is the same as that of the fourth hydraulic cylinder 6.

[0045] It also includes a first high-pressure mist pump 54, a second high-pressure mist pump 64, a first mist pump pipe 52, a second mist pump pipe 62, a first spray valve 56, a second spray valve 66, a first nozzle 55 and a second nozzle 65; both ends of the first mist pump pipe 52 are arranged in the third hydraulic cylinder 5, and both ends of the second mist pump pipe 62 are arranged in the fourth hydraulic cylinder 6, the first high-pressure mist pump 54 and the first spray valve 56 are connected to the first mist pump pipe 52, a plurality of first nozzles 55 are arranged at the top of the third hydraulic cylinder 5, and are connected to one end of the first mist pump pipe 62, the second high-pressure mist pump 64 and the second spray valve 66 are connected to the second mist pump pipe 62, and a plurality of second nozzles 65 are arranged at the top of the fourth hydraulic cylinder 6, and are connected to one end of the second mist pump pipe 62.

[0046] The gas expansion device also includes a second high-pressure air intake pipe 88, a third vent valve 53, a second high-pressure air intake valve 67, a second wheel group water inlet valve 77, a second wheel group drain valve 75 and a fourth pipeline 84. The second high-pressure air intake pipe 88 is arranged at the top of the fourth hydraulic cylinder 6, and the fourth hydraulic cylinder 6 is connected to the high-pressure gas tank 4 through the second high-pressure air intake pipe 88. The second high-pressure air intake valve 67 is arranged on the second high-pressure air intake pipe 88, the third vent valve 53 is arranged on the top of the third hydraulic cylinder 5, and the third hydraulic cylinder 5 is connected to the fourth hydraulic cylinder 6 through the fourth pipeline 84. The second wheel group water inlet valve 77, the wheel group 72 and the second wheel group drain valve 75 are connected to the fourth pipeline 84 in sequence.

[0047] When gas expands to generate electricity, two operating modes need to be discussed. First, regulating the gas valve: by obtaining the temperature and pressure in the high-pressure gas tank and the gas pressure and temperature in the hydraulic tank, and then adjusting the gas valve opening accordingly, when the pressure in the hydraulic cylinder remains roughly constant, the water head in the cylinder is roughly constant, and the turbine can generate electricity under a relatively constant water head. However, after the liquid in the cylinder is emptied, the remaining gas pressure in the tank is wasted. Second, if a certain amount of high-pressure gas is introduced through the regulating gas valve, the pressure in the tank changes, that is, the water head changes. By changing the number of turbines in series, the turbine unit can maintain a high power generation efficiency. The third hydraulic cylinder 5 and the fourth hydraulic cylinder 6 are both variable cross-section structures. As the height of the third hydraulic cylinder 5 and the fourth hydraulic cylinder 6 decreases, the cross-sectional area of the third hydraulic cylinder 5 and the fourth hydraulic cylinder 6 increases.

[0048] When a certain amount of high-pressure gas is introduced, the third hydraulic cylinder 5 is filled with liquid. When the high-pressure gas in the high-pressure gas tank 4 expands in the third hydraulic cylinder 5 to generate electricity:

[0049] The first high-pressure mist pump 54 of the third hydraulic cylinder 5 is operated, and the high-pressure gas expands to make the liquid in the third hydraulic cylinder 5 have a higher water head. The high-head liquid impacts the wheel group 72 to generate electricity. Since the fourth hydraulic cylinder 6 is connected to the atmosphere, different numbers of turbines running in series are selected according to the real-time pressure in the third hydraulic cylinder 5. This is achieved by adjusting the wheel group series valve 73 and the wheel group drain valve 74. The liquid after power generation flows into the fourth hydraulic cylinder 6 through the pipeline.

[0050] As the high-pressure gas expands in the third hydraulic cylinder 5, its temperature will inevitably drop. The expanded gas and liquid transfer heat from liquid to gas at the gas-liquid interface, reducing the temperature drop of the expanded gas. At the same time, the operating first high-pressure mist pump 54 sprays the liquid in the third hydraulic cylinder 5 through the first mist pump pipe 52 and the first nozzle 55 in the form of mist. During the falling process, the mist droplets come into contact with the expanding gas, releasing heat to the expanding gas, further reducing the temperature drop of the expanding gas, and the mist droplets finally fall into the liquid. As the liquid level in the third hydraulic cylinder 5 rises and drops, the pressure drop ratio increases, and the temperature of the expanding gas becomes lower and lower. At this time, the cross-sectional area of the third hydraulic cylinder 5 increases as the liquid level drops, the liquid-gas contact surface area increases, and the heat exchange capacity of the liquid-gas surface increases. At the same time, the falling height of the spray from spraying to falling into the liquid increases, the contact time of the spray and gas increases, and the heat exchange capacity of the spray and gas also increases accordingly, that is, the heat exchange between the gas and liquid increases as the liquid level drops, so that the expansion process is closer to an isothermal process. Until the liquid level in the third hydraulic cylinder 5 drops to a certain height, the high-pressure gas expands and drives the liquid in the third hydraulic cylinder 5 to generate electricity through the wheel set 72.

[0051] At this point, the fourth hydraulic cylinder 6 is filled with liquid. By switching valves, high-pressure gas drives the liquid in the fourth hydraulic cylinder 6 through the wheel assembly 72 to generate electricity. The expansion of the high-pressure gas gives the liquid in the hydraulic cylinder 6 a high head. This high-head liquid impacts the wheel assembly 72, generating electricity. Because the third hydraulic cylinder 5 is connected to the atmosphere, a different number of turbines can be selected for series operation based on the real-time pressure within the fourth hydraulic cylinder 6. This is achieved by adjusting the wheel assembly series valve 73 and the wheel assembly drain valve 74. The generated liquid then flows through a pipeline into the third hydraulic cylinder 5. Similar to the aforementioned process of high-pressure gas driving the liquid in the third hydraulic cylinder 5 through the wheel assembly 72 to generate electricity, the expansion of the high-pressure gas in the fourth hydraulic cylinder 6 becomes isothermal through gas-liquid contact, gas-mist mixing, and an increase in the gas-liquid contact surface. Once the liquid level in the fourth hydraulic cylinder 6 drops to a certain level, the high-pressure gas expansion drives the liquid in the fourth hydraulic cylinder 6 through the turbine assembly 72, concluding the power generation process.

[0052] At this point, the third hydraulic cylinder 5 is filled with liquid. By switching valves, high-pressure gas propels the liquid in the third hydraulic cylinder 5 through the wheel assembly 72 to generate electricity. This alternating expansion of high-pressure gas in the third and fourth hydraulic cylinders 5, 6, achieves continuous power generation. When the liquid temperature in the third and fourth hydraulic cylinders 5, 6 is low and the heat exchange effect is poor, the liquid in the third or fourth hydraulic cylinder 5, 6 can be replaced using the pump assembly water change inlet valve 38, the pump assembly water change drain valve 39, and the wheel assembly water change switching valve 78.

[0053] A near-isothermal compressed air energy storage method:

[0054] Step (1), the second hydraulic cylinder 2 compresses air to store energy: first, the first hydraulic cylinder 1 is filled with liquid, and when the air in the second hydraulic cylinder 2 is compressed, the first ventilation valve 14, the first drainage valve 16, the first pump group water inlet valve 37, the first pump group drainage valve 35 and the second water inlet valve 27 are opened, and other valves are closed; the pump group 32 is running, and since the first hydraulic cylinder 1 is connected to the atmosphere, different numbers of water pumps running in series are selected according to the real-time pressure requirements in the second hydraulic cylinder 2 to pump the liquid from the first hydraulic cylinder 1 into the second hydraulic cylinder 2; as the liquid level in the second hydraulic cylinder 2 rises, the volume occupied by the air in the second hydraulic cylinder 2 decreases and is compressed, and the compressed gas and liquid undergo gas-liquid heat transfer at the gas-liquid interface, and the liquid absorbs the compression heat to reduce the temperature of the compressed gas; and the water flowing into the second hydraulic cylinder 2 passes through the second hydraulic cylinder 2 The porous plate 23 inside is divided into multiple streams through the holes and falls into the lower part of the second hydraulic cylinder 2. The falling process fully mixes with the compressed gas and exchanges heat, further reducing the temperature of the compressed gas; as the liquid level rises, the compression ratio of the gas becomes larger and larger, and the gas temperature becomes higher and higher. At this time, the cross-sectional area of the second hydraulic cylinder 2 increases with the increase of the liquid level, the contact area of the gas-liquid surface increases, and the heat exchange capacity is further enhanced; the above cooling measures make the gas compression process more close to an isothermal process; when the compressed gas in the second hydraulic cylinder 2 reaches a certain pressure, the second high-pressure exhaust valve 25 is opened, and the high-pressure gas is discharged into the high-pressure gas tank 4, and the pump group 32 continues to run until the liquid level fills the hydraulic cylinder 2, and the gas in the second hydraulic cylinder 2 is completely compressed into the high-pressure gas tank 4, and the second high-pressure exhaust valve 25 is closed, and the gas compression process in the second hydraulic cylinder 2 is completed.

[0055] Step (2), the first hydraulic cylinder 1 compresses gas to store energy: open the first water inlet valve 17, the second vent valve 24 and the second drain valve 26, the second pump group water inlet valve 31 and the second pump group drain valve 36, and close the other valves; the energy storage principle is the same as that of step (1), so that continuous gas compression is achieved by alternating the operation of the first hydraulic cylinder 1 and the second hydraulic cylinder 2.

[0056] Step (3), the gas in the third hydraulic cylinder 5 expands to generate electricity: the third hydraulic cylinder 5 is filled with liquid, and the following valves are opened: the third high-pressure air inlet valve 57, the first high-pressure air inlet valve 57, the first wheel group water inlet valve 71, the first spray valve 56, the first wheel group drain valve 76 and the fourth vent valve 63, and the other valves are closed; the first high-pressure mist pump 54 is operated, and the high-pressure gas expands to make the liquid in the third hydraulic cylinder 5 have a higher water head. The high-head liquid impacts the wheel group 72 to generate electricity. At the same time, the operating first high-pressure mist pump 54 sprays the liquid in the third hydraulic cylinder 5 in the form of mist through the multiple first mist pump pipes 52 and the multiple first nozzles 55 arranged on the top of the third hydraulic cylinder 5, covering a large area of the expansion space in the hydraulic cylinder. During the falling process, the mist droplets come into contact with the expanding gas, release heat to the expanding gas, further reduce the temperature drop of the expanding gas, and finally fall into the liquid; until the liquid level in the third hydraulic cylinder 5 drops to a certain height, the high-pressure gas expansion drives the liquid in the third hydraulic cylinder 5 through the wheel group 72 to end the power generation.

[0057] Step (4), gas expansion in the fourth hydraulic cylinder 6 to generate electricity: at this time, the hydraulic cylinder 6 is filled with liquid, the second high-pressure mist pump 64, the second spray valve 66, the second high-pressure gas valve 67, the third vent valve 54, the second wheel group water inlet valve 77, the second wheel group drain valve 75 are opened, and other valves are closed. The power generation principle is the same as that in step (3), so that the high-pressure gas drives the liquid in the second hydraulic cylinder 6 to generate electricity through the wheel group 72 until the liquid level in the fourth hydraulic cylinder 6 drops to a certain height, and the high-pressure gas expands to drive the liquid in the second hydraulic cylinder 6 to generate electricity through the wheel group 72. In this way, continuous power generation is achieved by alternately expanding the high-pressure gas in the third hydraulic cylinder 5 and the fourth hydraulic cylinder 6.

[0058] The preferred embodiments of the present invention are described in detail above. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various equivalent transformations can be made to the technical solutions of the present invention, and these equivalent transformations all fall within the scope of protection of the present invention.

Claims

1. A near-isothermal compressed air energy storage device, characterized in that: The invention comprises a first hydraulic cylinder (1), a second hydraulic cylinder (2), a first vent valve (14), a first drain valve (16), a first pump group water inlet valve (37), a first pump group drain valve (35), a second water inlet valve (27), a pump group (32), a high-pressure gas tank (4), a first pipeline (81), a second high-pressure exhaust pipe (86), a second high-pressure exhaust valve (25), a second pipeline (82), a second vent valve (24), a first water inlet valve (17), a second drain valve (26), a second pump group water inlet valve (31), a second pump group drain valve (36), a first high-pressure exhaust pipe (85), a first high-pressure exhaust valve (15), a first porous plate (13), and a second porous plate (23); the first hydraulic cylinder (1) and the second hydraulic cylinder (2) are vented. The first hydraulic cylinder (1) and the second hydraulic cylinder (2) are connected through a first pipe (81), one end of the first pipe (81) is connected to the bottom of the first hydraulic cylinder (1), and the other end of the first pipe (81) is connected to the second hydraulic cylinder (2). The volume of the first hydraulic cylinder (1) is the same as the volume of the second hydraulic cylinder (2); the first vent valve (14) is arranged on the top of the first hydraulic cylinder (1), the first drain valve (16), the first pump group water inlet valve (37), the pump group (32), the first pump group drain valve (35) and the second water inlet valve (27) are connected to the first pipe (81) in sequence, and the pump group (32) includes a plurality of water pumps connected in series; the second high-pressure exhaust pipe (86) is arranged on the top of the second hydraulic cylinder (2), and the second hydraulic cylinder (2) and the high-pressure gas tank (4) are connected through the second high-pressure exhaust pipe (86). The second high-pressure exhaust valve (25) is arranged on the second high-pressure exhaust pipe (86); the first hydraulic cylinder (1) and the second hydraulic cylinder (2) are connected through the second pipe (82), one end of the second pipe (82) is connected to the bottom of the second hydraulic cylinder (2), and the other end of the second pipe (82) is connected to the first hydraulic cylinder (1); the second vent valve (24) is arranged on the top of the second hydraulic cylinder (2), the first water inlet valve (17), the second pump group drain valve (36), the pump group (32), the second pump group water inlet valve (31) and the second drain valve (26) are connected to the second pipe (82) in sequence; the first high-pressure exhaust pipe (85) is arranged on the top of the first hydraulic cylinder (1), and the first hydraulic cylinder (1) and the high-pressure gas tank (4) are connected through the first high-pressure exhaust pipe. (85) is connected, and the first high-pressure exhaust valve (15) is arranged on the first high-pressure exhaust pipe (85); the first porous plate (13) is mounted on the inner wall of the first hydraulic cylinder (1), and the vertical height of one end of the second pipe (82) extending into the first hydraulic cylinder (1) is greater than the vertical height of the first porous plate (13); the second porous plate (23) is mounted on the inner wall of the second hydraulic cylinder (2), and the vertical height of one end of the first pipe (81) extending into the second hydraulic cylinder (2) is greater than the vertical height of the second porous plate (23); the cross-sections of the first hydraulic cylinder (1) and the second hydraulic cylinder (2) are both variable cross-section structures, and as the heights of the first hydraulic cylinder (1) and the second hydraulic cylinder (2) increase, the cross-sectional areas of the first hydraulic cylinder (1) and the second hydraulic cylinder (2) increase.

2. The near-isothermal compressed air energy storage device according to claim 1, characterized in that: The pump group water exchange inlet pipe, the pump group water exchange drain pipe, the pump group water exchange inlet valve (38) and the pump group water exchange drain valve (39) are further included. The pump group water exchange inlet pipe is connected to the water inlet end of the pump group (32), the pump group water exchange drain pipe is connected to the drain end of the pump group (32), the pump group water exchange inlet valve (38) is arranged on the pump group water exchange inlet pipe, and the pump group water exchange drain valve (39) is arranged on the pump group water exchange drain pipe.

3. The near-isothermal compressed air energy storage device according to claim 1, characterized in that: The invention also includes a gas expansion power generation device, which includes a third hydraulic cylinder (5), a first high-pressure air intake pipe (87), a first high-pressure air intake valve (57), a first wheel group water intake valve (71), a first wheel group water discharge valve (76), a fourth vent valve (63), a third pipeline (83), a wheel group (72) and a fourth hydraulic cylinder (6); the first high-pressure air intake pipe (87) is arranged on the top of the third hydraulic cylinder (5), and the third hydraulic cylinder (5) is connected to the high-pressure gas tank (4) through the first high-pressure air intake pipe (87). The first high-pressure air inlet valve (57) is arranged on the first high-pressure air inlet pipe (87); the fourth air vent valve (63) is arranged on the top of the fourth hydraulic cylinder (6); the third hydraulic cylinder (5) and the fourth hydraulic cylinder (6) are connected through the third pipe (83); the first wheel group drain valve (76), the wheel group (72) and the first wheel group water inlet valve (71) are connected to the third pipe (83) in sequence; the wheel group (72) includes a plurality of turbines connected in series; the volume of the third hydraulic cylinder (5) is the same as the volume of the fourth hydraulic cylinder (6).

4. The near-isothermal compressed air energy storage device according to claim 3, characterized in that: The gas expansion device further comprises a second high-pressure air intake pipe (88), a third vent valve (53), a second high-pressure air intake valve (67), a second wheel group water inlet valve (77), a second wheel group drain valve (75) and a fourth pipe (84). The second high-pressure air intake pipe (88) is arranged at the top of the fourth hydraulic cylinder (6). The fourth hydraulic cylinder (6) is connected to the high-pressure gas tank (4) through the second high-pressure air intake pipe (88). The second high-pressure air intake valve (67) is arranged on the second high-pressure air intake pipe (88). The third vent valve (53) is arranged on the top of the third hydraulic cylinder (5). The third hydraulic cylinder (5) is connected to the fourth hydraulic cylinder (6) through the fourth pipe (84). The second wheel group water inlet valve (77), the wheel group (72) and the second wheel group drain valve (75) are sequentially connected to the fourth pipe (84).

5. The near-isothermal compressed air energy storage device according to claim 4, characterized in that: The invention also includes a first high-pressure mist pump (54), a second high-pressure mist pump (64), a first mist pump pipe (52), a second mist pump pipe (62), a first spray valve (56), a second spray valve (66), a first nozzle (55) and a second nozzle (65); both ends of the first mist pump pipe (52) are arranged in the third hydraulic cylinder (5), both ends of the second mist pump pipe (62) are arranged in the fourth hydraulic cylinder (6), the first high-pressure mist pump (54) and the first spray valve (56) are connected to the first mist pump pipe (52), a plurality of first nozzles (55) are arranged on the top of the third hydraulic cylinder (5) and connected to one end of the first mist pump pipe (52), the second high-pressure mist pump (64) and the second spray valve (66) are connected to the second mist pump pipe (62), and a plurality of second nozzles (65) are arranged on the top of the fourth hydraulic cylinder (6) and connected to one end of the second mist pump pipe (62).

6. The near-isothermal compressed air energy storage device according to claim 3, characterized in that: The third hydraulic cylinder (5) and the fourth hydraulic cylinder (6) are both of variable cross-section structures; as the heights of the third hydraulic cylinder (5) and the fourth hydraulic cylinder (6) decrease, the cross-sectional areas of the third hydraulic cylinder (5) and the fourth hydraulic cylinder (6) increase.

7. An energy storage method based on the near-isothermal compressed air energy storage device according to claim 5, characterized in that: Step (1), the second hydraulic cylinder (2) compresses air to store energy: first, the first hydraulic cylinder (1) is filled with liquid, and when the air in the second hydraulic cylinder (2) is compressed, the first ventilation valve (14), the first drainage valve (16), the first pump group water inlet valve (37), the first pump group drainage valve (35) and the second water inlet valve (27) are opened, and the other valves are closed; the pump group (32) is operated, and since the first hydraulic cylinder (1) is connected to the atmosphere, different numbers of water pumps running in series are selected according to the real-time pressure size requirements in the second hydraulic cylinder (2) to pump the liquid from the first hydraulic cylinder (1) into the second hydraulic cylinder (2); as the liquid level in the second hydraulic cylinder (2) rises, the volume occupied by the air in the second hydraulic cylinder (2) decreases and is compressed, and the compressed gas and the liquid undergo gas-liquid heat transfer at the gas-liquid interface, and the liquid absorbs the compression heat to reduce the temperature of the compressed gas; The water flow into the second hydraulic cylinder (2) passes through the second porous plate (23) in the second hydraulic cylinder (2), and the water flow through the holes is transformed into multiple thin streams and falls into the lower part of the second hydraulic cylinder (2). The water flow is fully mixed with the compressed gas during the falling process, and the heat exchange is further reduced, and the temperature of the compressed gas is further reduced. As the liquid level rises, the compression ratio of the gas becomes larger and larger, and the gas temperature becomes higher and higher. At this time, the cross-sectional area of the second hydraulic cylinder (2) increases with the increase of the liquid level, the gas-liquid surface contact area increases, and the heat exchange capacity is further enhanced. The above cooling measures make the gas compression process closer to an isothermal process. When the compressed gas in the second hydraulic cylinder (2) reaches a certain pressure, the second high-pressure exhaust valve (25) is opened, and the high-pressure gas is discharged into the high-pressure gas tank (4). The pump group (32) continues to operate until the liquid level fills the second hydraulic cylinder (2), and the gas in the second hydraulic cylinder (2) is completely compressed into the high-pressure gas tank (4). The second high-pressure exhaust valve (25) is closed, and the gas compression process in the second hydraulic cylinder (2) is completed. Step (2), the first hydraulic cylinder (1) compresses gas to store energy: open the first water inlet valve (17), the second vent valve (24) and the second drain valve (26), the second pump group water inlet valve (31) and the second pump group drain valve (36), and close the other valves; the energy storage principle is the same as that of step (1), and continuous gas compression is achieved by alternating the operation of the first hydraulic cylinder (1) and the second hydraulic cylinder (2); Step (3), the third hydraulic cylinder (5) expands the gas to generate electricity: the third hydraulic cylinder (5) is filled with liquid, and the following valves are opened: the first high-pressure air inlet valve (57), the first wheel group water inlet valve (71), the first spray valve (56), the first wheel group drain valve (76) and the fourth vent valve (63), and the other valves are closed; the first high-pressure mist pump (54) is operated, and the high-pressure gas expands to make the liquid in the third hydraulic cylinder (5) have a higher water head, and the high-head liquid impacts the wheel group (72) to generate electricity, and at the same time the first high-pressure mist pump (54) is operated to pump the first high-pressure mist pump (54) The liquid in the three hydraulic cylinders (5) is sprayed out in a mist form through the multiple first mist pump pipes (52) and the first nozzle (55) arranged on the top of the third hydraulic cylinder (5), covering the expansion space in the third hydraulic cylinder (5) over a large area. The mist droplets come into contact with the expansion gas during their falling process, releasing heat to the expansion gas, further reducing the temperature drop of the expansion gas, and the mist droplets finally fall into the liquid; until the liquid level in the third hydraulic cylinder (5) drops to a certain height, the high-pressure gas expands and drives the liquid in the third hydraulic cylinder (5) through the wheel group (72) to complete the power generation; Step (4), gas expansion in the fourth hydraulic cylinder (6) to generate electricity: at this time, the fourth hydraulic cylinder (6) is filled with liquid, the second high-pressure mist pump (64), the second spray valve (66), the second high-pressure air inlet valve (67), the third vent valve (53), the second wheel group water inlet valve (77), the second wheel group drain valve (75) are opened, and other valves are closed. The power generation principle is the same as that in step (3), so that the high-pressure gas drives the liquid in the second hydraulic cylinder (2) through the wheel group (72) to generate electricity until the liquid level in the fourth hydraulic cylinder (6) drops to a certain height, and the high-pressure gas expands to drive the liquid in the second hydraulic cylinder (2) through the wheel group (72) to end the power generation. In this way, continuous power generation is achieved by alternately expanding the high-pressure gas in the third hydraulic cylinder (5) and the fourth hydraulic cylinder (6).

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