A compressed air piston hydraulic gravity energy storage system and method

Abstract

This invention discloses a compressed air piston-water gravity energy storage system and method. In the system, a cooler group is installed in the compressed air energy storage system. The hot-side outlet of the cooler group is connected to a high-pressure gas tank group, and a hot storage tank is installed at the cold-side outlet of the cooler group. A pre-installed heater is installed at the outlet of the piston-water gravity energy storage system. The high-pressure air outlet of the pre-installed heater and the outlet of the high-pressure gas tank group are connected to the working fluid inlet of the air expansion energy release system. A heater group is installed in the air expansion energy release system. The hot-side inlet of the heater group is connected to the hot storage tank; the hot-side outlet of the heater group is connected to a cold storage tank; the outlet of the cold storage tank is connected to the hot-side inlet of the pre-installed heater; and the hot-side outlet of the pre-installed heater is connected to the cold-side inlet of the cooler group. The water inlet and outlet of the piston-water gravity energy storage system are connected to a water storage tank via a water pump and a turbine unit. This system enables the cascade utilization of pressure potential energy and water kinetic energy, improves the flexibility of energy storage system layout and installation, and enhances energy utilization and conversion efficiency.

Description

Technical Field

[0001] This invention belongs to the field of physical energy storage and relates to a compressed air piston hydraulic gravity energy storage system and method. Background Technology

[0002] With increasing attention being paid to the environmental problems and resource finiteness of traditional fossil fuels, renewable energy sources such as solar and wind power are being vigorously developed globally. However, these energy sources are characterized by intermittency and volatility. New energy storage technologies can store energy when there is a surplus and release it when there is a shortage, thereby effectively regulating the stability of energy supply and enabling renewable energy to be better integrated into the grid.

[0003] Currently, compressed air energy storage systems and pumped hydro storage systems are both relatively mature large-scale energy storage technologies, and they play a significant role in alleviating the volatility and intermittency issues in renewable energy power generation.

[0004] Gravity energy storage, as a new type of energy storage technology, has a broad development prospect. Pumped hydro storage, as a type of gravity energy storage, has the advantages of high energy conversion efficiency, large energy storage capacity, and long energy storage time, but it has high construction costs and strict requirements for geographical location.

[0005] The combined energy storage of compressed air systems and insulation systems is gradually gaining attention. This energy storage method recycles the heat generated during the compression and expansion of air, significantly improving the overall efficiency and energy utilization of the system. Meanwhile, novel energy storage methods combining compressed air storage and gravity storage show great promise. For example, using gravity blocks to compress air, leveraging the compressibility of air to control the rise and fall of the gravity blocks, and using the gravity blocks to drive a motor to generate electricity. However, due to the heat generated and lost during air compression and expansion, this energy storage method still has some drawbacks.

[0006] There is an urgent need for a new type of energy storage that addresses the shortcomings of the aforementioned energy storage methods. Summary of the Invention

[0007] The purpose of this invention is to provide a compressed air piston hydraulic gravity energy storage system and method to solve the problems of low energy conversion efficiency and short energy storage time in traditional gravity energy storage systems.

[0008] To achieve the above objectives, the present invention adopts the following technical solution: a compressed air piston-hydraulic gravity energy storage system, comprising an air compression energy storage system, an air expansion energy release system, and a piston-hydraulic gravity energy storage and release system; a cooler group is provided in the air compression energy storage system, the hot-side outlet of the cooler group is connected to a high-pressure gas tank group, and a hot storage tank is provided at the cold-side outlet of the cooler group; a pre-installed heater is provided at the outlet of the piston-hydraulic gravity energy storage and release system, the high-pressure air outlet of the pre-installed heater and the outlet of the high-pressure gas tank group are connected to the working fluid inlet of the air expansion energy release system, the high-pressure air outlets of the air compression energy storage system and the piston-hydraulic gravity energy storage and release system are connected to the working fluid inlet of the air expansion energy release system, a heater group is provided in the air expansion energy release system, the hot-side inlet of the heater group is connected to the hot storage tank, and the cold-side inlet of the heater group serves as the working fluid inlet; the hot-side outlet of the heater group is connected to a cold storage tank, the outlet of the cold storage tank is connected to the hot-side inlet of the pre-installed heater, and the hot-side outlet of the pre-installed heater is connected to the cold-side inlet of the cooler group; the water inlet and outlet of the piston-hydraulic gravity energy storage and release system are connected to a water storage tank through a water pump and a water turbine unit.

[0009] Furthermore, the air expansion energy release system includes a cold side of a first preheater, a high-pressure expander, a cold side of an intermediate heater, and a low-pressure expander connected along the working fluid flow direction. The hot side inlet of the intermediate heater is connected to the outlet of the heat storage tank, the hot side outlet of the intermediate heater is connected to the hot side inlet of the first preheater, and the hot side outlet of the first preheater is connected to the inlet of the preheater.

[0010] Furthermore, the air compression energy storage system includes a low-pressure compressor and a high-pressure compressor, and the cooler group includes an intercooler and an aftercooler. The low-pressure compressor, the hot side of the intercooler, the high-pressure compressor, and the hot side of the aftercooler are connected sequentially along the medium flow direction. The hot side outlet of the aftercooler is connected to the high-pressure gas tank and the high-pressure gas tank. The cold side outlet of the intercooler is connected to the heat storage tank, and the cold side inlet of the aftercooler is connected to the hot side outlet of the pre-installed heater.

[0011] Furthermore, the piston-water gravity energy storage and release system includes a piston, a gravity well, a water pump, a water turbine, and a water storage tank. The piston divides the gravity well into upper and lower parts: an air chamber and a liquid chamber. The air chamber of the gravity well is connected to a compressed air system, and the liquid chamber of the gravity well is connected to the water storage tank via a water pump and a water turbine unit.

[0012] Furthermore, several nozzles are installed at the top of the air chamber of the gravity well, and a water storage tank is connected to the nozzles.

[0013] Furthermore, the air chamber outlet of the gravity well is connected to a water vapor separator, the gas outlet of the water vapor separator is connected to the cold side inlet of the pre-installed heater, and the water outlet of the water vapor separator is connected to a water storage tank.

[0014] Furthermore, the piston is made of iron ore, the gravity well is made of stainless steel or reinforced concrete, and the inner wall of the gravity well has a smooth surface; the piston and the inner wall of the gravity well are sealed with an O-ring, and pressure sensors and temperature sensors are installed inside the gravity well, the first high-pressure gas tank and the second high-pressure gas tank.

[0015] Furthermore, the reservoirs can be natural lakes or artificial reservoirs.

[0016] This invention also provides a method for operating the above-mentioned compressed air piston hydraulic gravity energy storage system, including:

[0017] The air compression energy storage system compresses air to generate heat energy and high-pressure air. The heat energy is stored in a heat storage tank through a cooler group, and the high-pressure air is stored in a high-pressure gas tank group. The medium in the heat storage tank is stored in a cold storage tank after releasing heat.

[0018] Water in the reservoir enters the piston-water gravity energy storage and release system, which drives the piston to compress the air in the piston-water gravity energy storage and release system, generating high-pressure air.

[0019] In the piston-water gravity energy storage and release system, high-pressure air absorbs heat in a preheated heater and then expands and performs work in the air expansion energy release system before being discharged to the external environment. Similarly, high-pressure air from the high-pressure gas tank group enters the air expansion energy release system, expands and performs work, and is then discharged to the external environment. Water from the reservoir enters the piston-water gravity energy storage and release system, and the system operates at constant pressure during the compressed air energy release process. As the water from the piston-water gravity energy storage and release system is discharged into the reservoir, it drives a water turbine to perform work and release energy. High-pressure air from the high-pressure gas tank group enters the piston-water gravity energy storage and release system to replenish air, and the system operates at constant pressure.

[0020] The high-pressure air from the high-pressure gas tank group, as well as the high-pressure air after absorbing heat, enters the heater group, absorbs heat, expands, and does work.

[0021] Furthermore, the piston-water gravity energy storage and release system includes a piston, a gravity well, a water pump, a water turbine, and a water storage tank. The piston divides the gravity well into upper and lower parts: an air chamber and a liquid chamber. The air chamber of the gravity well is connected to a compressed air system, and the liquid chamber of the gravity well is connected to the water storage tank via the water pump and water turbine unit. Several nozzles are installed at the top of the air chamber of the gravity well, and the water storage tank is connected to the nozzles. The outlet of the air chamber of the gravity well is connected to a water vapor separator, the gas outlet of the water vapor separator is connected to the cold side inlet of a pre-installed heater, and the outlet of the water vapor separator is connected to the water storage tank.

[0022] After the pressure of the high-pressure air tank group reaches the set value, water is pumped from the water storage tank into the liquid chamber of the gravity well. The air in the compressed air chamber is sprayed by the first drive water pump to the nozzle to cool the compressed air. After the pressure of the air chamber reaches the set value, the high-pressure air passes through the water vapor separator for gas-water separation. The high-pressure air enters the pre-set heater, and the water enters the water storage tank.

[0023] The operation of a compressed air piston hydraulic gravity energy storage system specifically includes a pre-compression process, an energy storage process, and an energy release process.

[0024] Energy storage process: Air enters the low-pressure compressor through a pressure pipeline, then passes through an intercooler into the high-pressure compressor, and finally flows into the aftercooler before entering the high-pressure gas tank. When the pressure in the high-pressure gas tank reaches the target value, a water pump is driven to draw water from the reservoir into the liquid chamber of the gravity well, thereby raising the piston and compressing the air chamber of the gravity well. Simultaneously, the water pump supplies water to the nozzles to spray water, reducing the temperature of the compressed air in the air chamber. When the pressure in the air chamber reaches the target value, the valve is opened, and the high-pressure air passes through a water-vapor separator and then enters the aftercooler for a second heat exchange. Finally, the gas is discharged into the expansion system to drive the high-pressure expander and the low-pressure expander to do work. At this point, the piston rises to the designated height in the gravity well, and the energy storage process of the device ends.

[0025] The liquid in the water-vapor separator is pumped into a storage tank. Additionally, the compressed air from the gravity well's air chamber can be stored directly in a high-pressure tank instead of doing work in the expansion system during this stage, ensuring constant pressure operation of the piston-water gravity system during the subsequent energy release process.

[0026] Energy release process: First, the piston in the gravity well uses its own gravitational potential energy to push water through the turbine, performing work and storing the water in a reservoir. During the piston's descent, the high-pressure air tank replenishes the air chamber to ensure constant pressure operation inside the gravity well, allowing the piston to descend stably. Once the piston reaches the designated height, the energy release process of the piston-water gravity system is complete. Then, the compressed air in the high-pressure air tank is released through pressure pipelines and enters the air expansion system to perform work on the high-pressure and low-pressure expanders. Finally, the air that has performed work is released into the atmosphere, thus ending the energy release process.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] This invention utilizes a compressed air system to further leverage the heat generated by compressed air during air expansion, and reuses the cooling energy generated by air expansion for the cooling process of compressed air, achieving cascade utilization of heat and effectively improving the working efficiency of the energy storage system. This invention combines a gravity energy storage system with an air compression system, allowing the two to work synergistically, providing a new approach to the joint storage and energy conversion of two clean energy sources, which is of great significance for achieving clean, efficient, long-term, and large-scale energy storage. Through pressure control measures, this invention enables the system to maintain stable operation under re-storage and energy release conditions, exhibiting good stability. The operation of this invention does not generate additional greenhouse gases such as carbon dioxide, and its environmental impact is negligible, contributing to sustainable development. The energy storage system of this invention has strong environmental adaptability, offering good economic benefits in mountainous, plateau, and plain areas.

[0029] Furthermore, the air compressed by the low-pressure compressor undergoes heat exchange in the intercooler and then enters the inlet of the high-pressure compressor through a pressure pipeline. The high-pressure gas generated in the high-pressure compressor enters the aftercooler through a pressure pipeline, undergoes heat exchange, and then is stored in the high-pressure gas tank group through a pressure pipeline, with the heat stored in the heat storage tank.

[0030] Furthermore, the inlet of the high-pressure expander is connected to the preheater and the high-pressure gas tank via a pressure pipeline, and the outlet is connected to the intermediate heater and the low-pressure expander. After the compressed air is released from the high-pressure gas tank, it undergoes heat exchange in the preheater, and then enters the high-pressure expander through the pressure pipeline to exchange heat with the intermediate heater, and then enters the low-pressure expander and enters the atmosphere through the pressure pipeline, thereby improving the efficiency of compressed air in doing work.

[0031] Furthermore, replacing water storage ponds with natural lakes or artificial reservoirs greatly reduces construction costs and makes it easier to achieve large-scale operations.

[0032] Furthermore, the gravity well's air chamber is equipped with nozzles connected to a water pump to cool the compressed air inside the air chamber.

[0033] Furthermore, during the compression process of the gravity well air chamber, a water pump supplies water to the nozzles to spray water and reduce the temperature of the air chamber. The compressed water vapor will then re-enter the water storage tank through the water vapor separator. During the energy release process, the high-pressure gas tank will replenish the gas to maintain a constant pressure inside the chamber. Attached Figure Description

[0034] Figure 1 This is a schematic diagram of the structure of a compressed air piston hydraulic gravity energy storage system according to the present invention.

[0035] Figure 2 This is a partial schematic diagram of the gravity well of the present invention.

[0036] In the diagram, 1-low-pressure compressor, 2-high-pressure compressor, 3-low-pressure expander, 4-high-pressure expander, 5-first high-pressure gas tank, 6-second high-pressure gas tank, 7-piston, 8-hot storage tank, 9-cold storage tank, 10-intercooler, 11-aftercooler, 12-intermediate heater, 13-first preheater, 14-preheater, 15-water-vapor separator, 16-water storage tank, 17-first drive pump, 18-pump, 19-pump, 20-turbine, 21-nozzle, 22-pressure sensor, 23-gravity well, 24-piston wall, 25-O-ring seal, 26-stainless steel wall. Detailed Implementation

[0037] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. The terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined with "first" and "second" may explicitly or implicitly include one or more of that feature.

[0038] The technical concept of this invention is as follows: A compressed air piston-hydraulic gravity energy storage system; comprising an air compression energy storage system, an air expansion energy release system, and a piston-hydraulic gravity energy storage and release system; a cooler group is provided in the air compression energy storage system, the hot-side outlet of the cooler group is connected to a high-pressure gas tank group, and a hot storage tank 8 is provided at the cold-side outlet of the cooler group; a pre-installed heater 14 is provided at the outlet of the piston-hydraulic gravity energy storage and release system, the high-pressure air outlet of the pre-installed heater 14 and the outlet of the high-pressure gas tank group are connected to the working fluid inlet of the air expansion energy release system, the high-pressure air outlets of the air compression energy storage system and the piston-hydraulic gravity energy storage and release system are connected to the working fluid inlet of the air expansion energy release system, a heater group is provided in the air expansion energy release system, the hot-side inlet of the heater group is connected to the hot storage tank 8, and the cold-side inlet of the heater group serves as the working fluid inlet; the hot-side outlet of the heater group is connected to a cold storage tank 9, the outlet of the cold storage tank 9 is connected to the hot-side inlet of the pre-installed heater 14, and the hot-side outlet of the pre-installed heater 14 is connected to the cold-side inlet of the cooler group; the water inlet and outlet of the piston-hydraulic gravity energy storage and release system are connected to a water storage tank 16 through a water pump and a water turbine unit.

[0039] During system operation, the air compression energy storage system compresses air to generate heat energy and high-pressure air. The heat energy is stored in the heat storage tank 8 through a cooler assembly, and the high-pressure air is stored in the high-pressure gas tank assembly. The medium in the heat storage tank 8 is stored in the cold storage tank 9 after releasing heat. Water in the water storage tank 16 enters the piston-water gravity energy storage and release system, which drives the piston to compress the air in the piston-water gravity energy storage and release system to generate high-pressure air. The high-pressure air in the piston-water gravity energy storage and release system absorbs heat in the pre-heated heater 14, then enters the air expansion energy release system to expand and do work before being discharged to the external environment. The high-pressure air from the group enters the air expansion energy release system, expands and does work, and is then discharged to the external environment; the water in the reservoir 16 enters the piston water gravity energy storage and release system, and the piston water gravity energy storage and release system operates at constant pressure during the compressed air energy release process; the water from the piston water gravity energy storage and release system drives the water turbine to do work and release energy during the discharge of the water from the piston water gravity energy storage and release system to the reservoir 16; the high-pressure air from the high-pressure gas tank group enters the piston water gravity energy storage and release system to replenish the air, and the piston water gravity energy storage and release system operates at constant pressure; the high-pressure air from the high-pressure gas tank group and the high-pressure air after absorbing heat enter the heater group, absorb heat, expand and do work.

[0040] Example 1, Figure 1 An example is a compressed air piston-hydraulic gravity energy storage system, which includes a compressed air energy storage system, an air expansion energy release system, a piston-containing water gravity energy storage system, and a thermal cycle system.

[0041] The compressed air energy storage system includes a low-pressure compressor 1, a high-pressure compressor 2, a first high-pressure air tank 5, and a second high-pressure air tank 6. The inlet of the low-pressure compressor 1 is connected to the atmosphere. The gas generated by the low-pressure compressor 1 enters the inlet of the high-pressure compressor 2 after heat exchange through the intercooler 10. The high-pressure air generated by the high-pressure compressor 2 enters the first high-pressure air tank 5 and the second high-pressure air tank 6 through pipelines after heat exchange through the aftercooler 11.

[0042] The air expansion energy release system includes a low-pressure expander 3 and a high-pressure expander 4. The high-pressure gas from the air chamber in the gravity well 23 and the compressed gas in the first high-pressure gas tank 5 and the second high-pressure gas tank 6 exchange heat in the pre-heater 14 and the first pre-heater 13, respectively, and then enter the air expansion energy release system. The gas first enters the high-pressure expander 4 through a pressure pipeline. After expanding and doing work, the gas enters the intermediate heater 12 for heat exchange and is then sent to the low-pressure expander 3 for further expansion and work. Finally, it is discharged into the atmosphere through a pipeline.

[0043] The thermal cycle system includes an intercooler 10, a postcooler 11, a first preheater 13, an intermediate heater 12, a hot storage tank 8, and a cold storage tank 9. The intercooler 10, the postcooler 11, and the preheater 14 are connected to the hot storage tank 8. The intermediate heater 12 and the first preheater 13 are connected between the hot storage tank 8 and the cold storage tank 9, thereby utilizing the heat generated in the compression system in the expansion system.

[0044] The water gravity energy storage system with piston includes a gravity well 23, a piston 7, a first drive water pump 17, a water pump 18, a water pump 19, a water turbine 20, a water storage tank 16, a nozzle 21, and a water vapor separator 15. The piston 7 is placed inside the gravity well 23, dividing the gravity well 23 into upper and lower parts. The upper part is an air chamber, and the lower part is a liquid chamber. The liquid chamber of the gravity well 23 is connected to the water pump and the water turbine through a pressure pipeline to the water storage tank 16. The air chamber is connected to the water vapor separator 15 through a pressure pipeline. The gas outlet of the water vapor separator 15 is connected to the gas inlet of 14, and further incorporated into the compressed air system.

[0045] As a further optimization, several nozzles are installed at the top of the air chamber of gravity well 23, and water storage tank 16 is connected to the nozzles to cool the compressed air in the air chamber.

[0046] The air chamber outlet of gravity well 23 is connected to water vapor separator 15, the gas outlet of water vapor separator 15 is connected to the cold side inlet of preheater 14, and the water outlet of water vapor separator 15 is connected to water storage tank 16. During the compression process of gravity well air chamber, water pump will supply water spray to nozzles to reduce the temperature of air chamber. The compressed water vapor will re-enter the water storage tank through water vapor separator. During the energy release process, high pressure gas tank will replenish gas to maintain constant pressure in chamber.

[0047] Furthermore, piston 7 is made of iron ore, and gravity well 23 is made of stainless steel or reinforced concrete, with a smooth inner wall. An O-ring seal is used between piston 7 and the inner wall of gravity well 23. Pressure and temperature sensors are installed inside gravity well 23, high-pressure gas tank 5, and high-pressure gas tank 6. The inner wall of gravity well 23 can be made of stainless steel, and an O-ring seal 25 is installed between piston wall 24 and the stainless steel wall.

[0048] Example 2, a method for operating a compressed air piston hydraulic gravity energy storage system according to the present invention, comprising:

[0049] Energy storage process:

[0050] Opening the first valve 101 on the pressure pipeline of the compression system allows ambient temperature and pressure air to enter the low-pressure compressor 1 for compression. At this time, the temperature and pressure of the air increase. After heat exchange in the intercooler 10, the air enters the high-pressure compressor 2 for a second compression, further increasing the pressure and temperature of the air. After cooling in the aftercooler 11, the air is stored in the first high-pressure gas tank 5. When the pressure sensor 22 in the first high-pressure gas tank 5 detects that the pressure in the tank has reached the target value, the second valve 102, the third valve 103, and the fourth valve 104 are opened, allowing additional gas to be delivered to the second high-pressure gas tank 6 through the pressure pipeline. When the pressure in the second high-pressure gas tank 6 reaches the target value, the second valve 102 and the first valve 101 are closed, and the low-pressure compressor 1 and the high-pressure compressor 2 stop working. When the eighth valve 108 and the ninth valve 109 are opened, the water pump 19 sends water from the water tank 16 into the water chamber of the gravity well 23. At the same time, the piston 7 is lifted and rises, reducing the volume of the air chamber in the gravity well. When the air in the air chamber is compressed to the target pressure value, the tenth valve 1010 is opened, and the first drive water pump 17 sends water from the water tank 16 through the nozzle 21 into the air chamber to cool the high-pressure air. Then, the sixth valve 106 is opened, and the high-pressure air enters the expansion system to do work after passing through the water vapor separator 15 and the aftercooler 14. At this time, there are two options: on the one hand, the fifth valve 105 can be opened to directly drive the high-pressure expander 4 and the low-pressure expander 3 to do work and generate electricity; on the other hand, the air in the gravity well 23 can be discharged into the first high-pressure air tank 5 and the second high-pressure air tank 6, waiting for the opportunity to do work and generate electricity.

[0051] Energy release process:

[0052] When the power grid is in peak electricity demand, the system needs to generate electricity. At this time, valves 107 (seventh), 109 (ninth), 106 (sixth), 104 (fourth), 103 (third), and 102 (second) are opened. Piston 7 descends, and water in the water tank enters the turbine 20 through the pressure pipeline to do work. Afterward, it is discharged into the reservoir 16. At the same time, the first high-pressure air tank 5 and the second high-pressure air tank 6 discharge compressed air through the pressure pipeline into the piston gravity energy storage system to replenish the air chamber of the gravity well 23, ensuring the stable descent of piston 7. Upon reaching the set altitude, valves 107 (seventh), 109 (ninth), and 106 (sixth) are closed, while valve 105 is opened. The remaining gas in the first high-pressure gas tank 5 and the second high-pressure gas tank 6 enters the first preheater 13 through a pressure pipeline for heating, and then enters the high-pressure expander 4. At this point, the air temperature decreases, and the pressure drops. The air, having undergone one expansion, then enters the intermediate heater 12 for a second heating before entering the low-pressure expander 3 through a pressure pipeline. The air temperature decreases again, and the pressure drops, finally being discharged into the atmosphere through a pressure pipeline. This completes the energy release process of the entire device, and the cycle begins again.

[0053] This invention discloses a compressed air piston-hydraulic gravity energy storage system and method. The system includes a compressed air energy storage system, an air expansion energy release system, a piston-containing water gravity energy storage system, and a thermal circulation system. The compressed air energy storage system includes a low-pressure compressor, a high-pressure compressor, and a high-pressure gas tank; the air expansion energy release system includes a low-pressure expander, a high-pressure expander, and a high-pressure gas tank; the piston-hydraulic gravity energy storage system includes a gravity well, a piston, a water pump, a water turbine, a water storage tank, a nozzle, and a water-vapor separator. The gravity well is divided into an air chamber and a water chamber by the piston. The air chamber is connected to the air compression system, and the water chamber is connected to the water turbine and the water pump; the thermal circulation system includes an intercooler, an aftercooler, a preheater, an intermediate heater, a hot storage tank, and a cold storage tank. This invention utilizes the characteristics of compressed air and incompressible water, linking them together through a piston system. The energy of the compressed air is stored in a high-pressure tank to drive an expander for power generation, and hydropower is used as the primary power generation method. The piston pushes the water body to do work in the turbine to generate electricity. At the same time, the heat generated in the compressed air is used in the expansion system, realizing the cascade utilization of pressure potential energy and water kinetic energy. Compared with traditional compressed air energy storage systems and pumped storage systems, this invention improves the flexibility of energy storage system layout and installation, and enhances energy utilization and conversion efficiency. It is an effective way to achieve efficient, economical, pollution-free, large-scale, long-term energy storage.

[0054] The above content is only for illustrating the technical concept of the present invention and should not be construed as limiting the scope of protection of the present invention. Any modifications made to the technical solution based on the technical concept proposed in this invention shall fall within the scope of protection of the claims of this invention.

Claims

1. A compressed air piston hydraulic gravity energy storage system, characterized in that, The system includes an air compression energy storage system, an air expansion energy release system, and a piston-water gravity energy storage and release system. The air compression energy storage system is equipped with a cooler group, whose hot-side outlet is connected to a high-pressure gas tank group. A hot storage tank (8) is installed at the cold-side outlet of the cooler group. A pre-installed heater (14) is installed at the outlet of the piston-water gravity energy storage and release system. The high-pressure air outlet and the outlet of the high-pressure gas tank group of the pre-installed heater (14) are connected to the working fluid inlet of the air expansion energy release system. A heater group is installed in the air expansion energy release system, whose hot-side inlet is connected to the hot storage tank (8). The cold-side inlet of the heater group serves as the working fluid inlet. The hot-side outlet of the heater group is connected to the cold storage tank (9). The outlet of the cold storage tank (9) is connected to the hot side inlet of the preheater (14), and the hot side outlet of the preheater (14) is connected to the cold side inlet of the cooler group; the water inlet and outlet of the piston water gravity energy storage system are connected to the reservoir (16) through the water pump and the turbine unit; the piston water gravity energy storage system includes a piston (7), a gravity well (23), a water pump (19), a turbine (20), and a reservoir (16); the piston (7) divides the gravity well (23) into an upper and lower part, an air chamber and a liquid chamber. The air chamber of the gravity well (23) is connected to the compressed air system, and the liquid chamber of the gravity well (23) is connected to the reservoir (16) through the water pump and the turbine unit.

2. The compressed air piston hydraulic gravity energy storage system according to claim 1, characterized in that, The air expansion energy release system includes the cold side of the first preheater (13), the high-pressure expander (4), the cold side of the intermediate heater (12), and the low-pressure expander (3) connected along the working fluid flow direction. The hot side inlet of the intermediate heater (12) is connected to the outlet of the heat storage tank (8), the hot side outlet of the intermediate heater (12) is connected to the hot side inlet of the first preheater (13), and the hot side outlet of the first preheater (13) is connected to the inlet of the preheater (14).

3. The compressed air piston hydraulic gravity energy storage system according to claim 1, characterized in that, The air compression energy storage system includes a low-pressure compressor (1) and a high-pressure compressor (2). The cooler group includes an intercooler (10) and a postcooler (11). The hot side of the low-pressure compressor (1), the intercooler (10), the high-pressure compressor (2), and the hot side of the postcooler (11) are connected in sequence along the medium flow direction. The hot side outlet of the postcooler (11) is connected to the first high-pressure gas tank (5) and the second high-pressure gas tank (6). The cold side outlet of the intercooler (10) is connected to the heat storage tank (8), and the cold side inlet of the postcooler (11) is connected to the hot side outlet of the preheater (14).

4. The compressed air piston hydraulic gravity energy storage system according to claim 1, characterized in that, Several nozzles are installed at the top of the air chamber of the gravity well (23), and the water storage tank (16) is connected to the nozzles.

5. The compressed air piston hydraulic gravity energy storage system according to claim 1, characterized in that, The air chamber outlet of the gravity well (23) is connected to the water vapor separator (15), the gas outlet of the water vapor separator (15) is connected to the cold side inlet of the preheater (14), and the water outlet of the water vapor separator (15) is connected to the water storage tank (16).

6. The compressed air piston hydraulic gravity energy storage system according to claim 1, characterized in that, The piston (7) is made of iron ore, and the gravity well (23) is made of stainless steel or reinforced concrete. The inner wall of the gravity well (23) is smooth. The piston (7) and the inner wall of the gravity well (23) are sealed with an O-ring. Pressure sensors and temperature sensors are installed inside the gravity well (23), the first high-pressure gas tank (5), and the second high-pressure gas tank (6).

7. The compressed air piston hydraulic gravity energy storage system according to claim 1, characterized in that, (16) A reservoir is a natural lake or a man-made reservoir.

8. The method of operating the compressed air piston hydraulic gravity energy storage system as described in any one of claims 1-7, characterized in that, include: The air compression energy storage system compresses air to generate heat energy and high-pressure air. The heat energy is stored in the heat storage tank (8) through the cooler group, and the high-pressure air is stored in the high-pressure air tank group. The medium in the heat storage tank (8) is stored in the cold storage tank (9) after releasing heat. Water in the reservoir (16) enters the piston-water gravity energy storage and release system, which drives the piston to compress the air in the piston-water gravity energy storage and release system to generate high-pressure air. The high-pressure air of the piston water gravity energy storage and release system absorbs heat in the pre-heated heater (14) and then enters the air expansion energy release system to expand and do work before being discharged to the external environment; the high-pressure air of the high-pressure gas tank group enters the air expansion energy release system to expand and do work before being discharged to the external environment; the water in the reservoir (16) enters the piston water gravity energy storage and release system, and the piston water gravity energy storage and release system operates at constant pressure during the compressed air energy release process; the water of the piston water gravity energy storage and release system is discharged to the reservoir (16) to drive the water turbine to do work and release energy; the high-pressure air of the high-pressure gas tank group enters the piston water gravity energy storage and release system to replenish the air, and the piston water gravity energy storage and release system operates at constant pressure; The high-pressure air from the high-pressure gas tank group, as well as the high-pressure air after absorbing heat, enters the heater group, absorbs heat, expands, and does work.

9. The operating method according to claim 8, characterized in that, The piston-water gravity energy storage and release system includes a piston (7), a gravity well (23), a water pump (19), a water turbine (20), and a water storage tank (16). The piston (7) divides the gravity well (23) into an upper and lower part, an air chamber and a liquid chamber. The air chamber of the gravity well (23) is connected to a compressed air system, and the liquid chamber of the gravity well (23) is connected to the water storage tank (16) via a water pump and a water turbine unit. Several nozzles are installed at the top of the air chamber of the gravity well (23), and the water storage tank (16) is connected to the nozzles. The outlet of the air chamber of the gravity well (23) is connected to a water vapor separator (15), the gas outlet of the water vapor separator (15) is connected to the cold side inlet of a pre-installed heater (14), and the outlet of the water vapor separator (15) is connected to the water storage tank (16). After the pressure of the high-pressure gas tank group reaches the set value, water is pumped from the water storage tank (16) into the liquid chamber of the gravity well (23). The air in the compressed air chamber is sprayed by the first drive water pump (17) to the nozzle (21) to cool the compressed air. After the pressure of the air chamber reaches the set value, the high-pressure air is separated into air and water by the water vapor separator (15). The high-pressure air enters the pre-heater (14), and the water enters the water storage tank (16).

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