Compressed air energy storage system with a fully closed-loop circulating water circuit

Abstract

This invention relates to the field of compressed air energy storage, and more particularly to a compressed air energy storage system with a fully closed-loop circulating water circuit. The system includes an electric motor, a compressor, an expander, a generator, an air storage device, an energy storage heat exchanger, an energy release heat exchanger, hot and cold water tanks, and a water pump, and integrates an oil-water heat exchanger and a water-water heat exchanger. The main air circuit sequentially connects the compressor, the high-temperature side of the energy storage heat exchanger, the air storage device, the low-temperature side of the energy release heat exchanger, and the expander. The fully closed-loop circulating water circuit connects the hot water tank, the hot water pump, the cold water tank, the cold water pump, the low-temperature side of the energy storage heat exchanger, the high-temperature side of the energy release heat exchanger, the oil-water heat exchanger, the water-water heat exchanger, and valves. This invention, through valve switching, utilizes the same water circuit to achieve the functions of hot water heating the oil tank before startup and cold water cooling the oil circuit and electrical equipment during operation, eliminating the need for a separate electric heater and cooling tower, recovering waste heat, and improving energy efficiency. It is suitable for new or renovated power plants.

Description

Technical Field

[0001] This invention relates to the field of compressed air energy storage technology, and in particular to a compressed air energy storage system with a fully closed circulating water circuit. Background Technology

[0002] Compressed air energy storage, with its advantages of large storage capacity, long service life, and no geographical limitations, has become a key supporting technology for new energy consumption and grid peak regulation in new power systems. Its basic principle is to use electricity to drive a compressor to compress air to a high-pressure state and store it in an air storage device during the off-peak period of grid load, while recovering the heat of compression through a heat storage medium. During the peak period of grid load, the high-pressure air is released, and the stored heat is used to heat it before it is sent to an expander to do work and drive a generator to generate electricity.

[0003] Water is widely used as a heat storage medium in compressed air energy storage systems due to its low cost, high safety, and environmental friendliness. During energy storage, water absorbs the heat of compression and is stored in a hot water tank; during energy release, the hot water releases heat to heat the air and then returns as cold water to the cold water tank, forming a closed loop. This type of closed-loop water system requires minimal water replenishment.

[0004] In existing compressed air energy storage systems, in addition to the thermal storage circulating water circuit, two other types of independent water circuit systems and their supporting equipment are usually installed in parallel: One type is the circulating cooling water loop, primarily used to cool the oil system (such as lubricating oil and fire-resistant oil) and the heat generated during equipment operation. This loop typically uses an open or semi-open cooling tower to directly discharge heat into the atmosphere. This design not only results in a significant waste of waste heat but also requires continuous replenishment of water due to evaporation and leakage, increasing water consumption and water treatment costs.

[0005] Secondly, there are dedicated cooling circuits for large electrical equipment. Core electrical components such as motor inverters and generator stators have extremely strict requirements for the physicochemical properties of the cooling medium (such as conductivity, pH value, oxygen content, and copper ion concentration). They typically require independent closed-loop circulation systems, and the heat generated by these core electrical components ultimately needs to be indirectly removed through the aforementioned circulating cooling water. Poor quality circulating cooling water can easily lead to scaling and corrosion in heat exchange equipment, affecting its lifespan and increasing maintenance frequency and costs.

[0006] Furthermore, compressed air energy storage power stations are characterized by intermittent operation, requiring lubricating oil and fire-resistant oil to reach specific temperature thresholds before the compressor or expander starts. In existing compressed air energy storage systems, the oil tank typically relies on a built-in electric heater for preheating, a process that consumes external electrical energy, increasing plant power consumption and reducing the overall economic efficiency of the system. Summary of the Invention

[0007] The present invention aims to overcome the shortcomings of the prior art and provide a compressed air energy storage system with a fully closed circulating water circuit, so as to solve the technical problems of existing compressed air energy storage systems, such as waste of waste heat, large water consumption, complex equipment cooling system, and high start-up energy consumption.

[0008] To achieve the above objectives, the technical solution created by this invention is implemented as follows: A compressed air energy storage system with a fully closed-loop circulating water circuit includes an electric motor, a compressor, an energy storage heat exchanger, an air storage device, an energy release heat exchanger, an expander, a generator, a hot water tank, a hot water pump, a cold water tank, a cold water pump, an oil-water heat exchanger, a water-water heat exchanger, and an oil tank; wherein, The output shaft of the electric motor is connected to the input shaft of the compressor, the outlet of the compressor is connected to the high-temperature side inlet of the energy storage heat exchanger, the high-temperature side outlet of the energy storage heat exchanger is connected to the inlet of the gas storage device, the outlet of the gas storage device is connected to the low-temperature side inlet of the energy release heat exchanger, the low-temperature side outlet of the energy release heat exchanger is connected to the inlet of the expander, and the outlet of the expander is connected to the generator. The low-temperature outlet of the energy storage heat exchanger is connected to the inlet of the hot water tank, and the outlet of the hot water tank is connected to the inlet of the hot water pump. The outlet of the hot water pump is divided into two paths: one path is connected to the high-temperature inlet of the energy release heat exchanger through the first valve, and the other path is connected to the water-side inlet of the oil-water heat exchanger through the second valve. The high-temperature outlet of the energy release heat exchanger is divided into two paths. One path of the high-temperature outlet is connected to the inlet of the cold water tank, and the outlet of the cold water tank is connected to the inlet of the cold water pump. The outlet of the cold water pump is also divided into two paths. One path of the cold water pump outlet is connected to the low-temperature inlet of the energy storage heat exchanger through the third valve, and the other path of the cold water pump outlet is divided into two paths after passing through the second valve. One path is connected to the water-side inlet of the oil-water heat exchanger, and the other path is connected to the primary water-side inlet of the water-water heat exchanger through the fifth valve. The other path of the high-temperature outlet is divided into two paths after passing through the fourth valve. One path is connected to the water-side inlet of the oil-water heat exchanger, and the other path is connected to the primary water-side inlet of the water-water heat exchanger through the fifth valve. The water-side outlet of the oil-water heat exchanger is divided into two paths: one path is connected to the inlet of the hot water tank through the sixth valve, and the other path is connected to the inlet of the cold water tank through the seventh valve. The oil-side inlet of the oil-water heat exchanger is connected to the outlet of the oil tank, and the oil-side outlet of the oil-water heat exchanger is connected to the inlet of the oil tank. The primary water-side outlet of the water-to-water heat exchanger is connected to the inlet of the hot water tank, the secondary water-side inlet of the water-to-water heat exchanger is connected to the outlet of the cooling circuit of the electrical equipment, and the secondary water-side outlet of the water heat exchanger is connected to the inlet of the cooling circuit of the electrical equipment.

[0009] Furthermore, both the hot water pump and the cold water pump are variable frequency pumps.

[0010] Furthermore, the fifth, sixth, and seventh valves are all regulating valves, while the first, second, third, and fourth valves are all on / off valves.

[0011] Furthermore, the heat exchange medium in both oil-water heat exchangers and water-water heat exchangers is demineralized water.

[0012] Furthermore, the oil tank includes a lubricating oil tank and / or a fire-resistant oil tank.

[0013] Furthermore, electrical equipment includes motor frequency converters and / or generator stators.

[0014] Furthermore, the compressed air energy storage system includes three operating modes: Fuel tank preheating mode: Before starting the compressor and / or expander, close the first, third, fourth, fifth, and sixth valves, and open the second and seventh valves; the hot water in the hot water tank enters the high-temperature side of the oil-water heat exchanger through the second valve after being pumped by the hot water pump, and after heating the oil tank, it becomes cold water and enters the cold water tank through the seventh valve; when the oil temperature in the oil tank reaches the temperature threshold, start the compressor and / or expander. Energy storage operating mode: Close valves 7, 4, and 1; open valves 2, 3, 5, and 6. An electric motor drives a compressor to generate high-temperature, high-pressure air, which then enters the high-temperature side of the energy storage heat exchanger. The cold water in the cold water tank is divided into three streams by the cold water pump. The first stream of cold water enters the low-temperature side of the energy storage heat exchanger through the third valve, cools the high-temperature and high-pressure air, and then enters the hot water tank. The high-temperature and high-pressure air is cooled to room temperature and high-pressure air and then enters the gas storage device for storage. The second stream of cold water enters the water side of the oil-water heat exchanger through the second valve, cools the oil tank, and then becomes hot water, which enters the hot water tank through the sixth valve. The third stream of cold water enters the primary water side of the water-water heat exchanger through the second and fifth valves, cools the electrical equipment, and then becomes hot water, which enters the hot water tank. Energy release operating mode: Close the second, third, and seventh valves, and open the first, sixth, fourth, fifth, and sixth valves; The ambient temperature high-pressure air in the gas storage device enters the low-temperature side of the energy release heat exchanger; Hot water from the hot water tank enters the high-temperature side of the energy release heat exchanger via a hot water pump and the first valve. After heating the ambient temperature high-pressure air, it becomes cold water and is divided into two streams. One stream of cold water enters the cold water tank, while the other stream of cold water is divided into two streams via the fourth valve. One stream of cold water enters the water side of the oil-water heat exchanger, cools the oil tank, and then becomes hot water, which enters the hot water tank via the sixth valve. The other stream of cold water enters the primary water side of the water-water heat exchanger, cools the electrical equipment, and then becomes hot water, which enters the hot water tank. The ambient temperature high-pressure air in the energy release heat exchanger is heated to become high-temperature high-pressure air, which enters the expander to do work and drive the generator to generate electricity.

[0015] Furthermore, in the tank preheating mode, the temperature of the lubricating oil and / or fire-resistant oil in the tank is controlled by adjusting the opening of the seventh valve.

[0016] Furthermore, in both energy storage and energy release modes, the temperature of the lubricating oil and / or fire-resistant oil in the tank is controlled by adjusting the opening of the sixth valve, and the temperature of the electrical equipment is controlled by adjusting the opening of the fifth valve.

[0017] Compared with the prior art, the present invention can achieve the following beneficial effects: 1. This invention utilizes hot water stored in a hot water tank to preheat the oil system (lubricating oil and fire-resistant oil) before the compressor or expander starts, via an oil-water heat exchanger. The flow rate of hot water is precisely controlled by a seventh valve, allowing the oil temperature to quickly reach the allowable starting conditions. This design replaces the traditional preheating method that relies on a built-in electric heater in the oil tank, avoiding external power consumption, reducing the power consumption of the compressed air energy storage power station, and improving the overall operational economy of the system.

[0018] 2. This invention, through the switching of the second and fourth valves, introduces cooling water supplied by the cold water pump or energy release heat exchanger during the energy storage and release processes into the oil-water heat exchanger and water-water heat exchanger, respectively, for cooling the oil circuit system and large electrical equipment. This system utilizes the existing main circulating water circuit for heat storage / exchange, simultaneously completing both oil circuit cooling and equipment cooling functions, eliminating the need for additional independent circulating cooling towers, cooling water pumps, and supporting pipelines. This not only reduces the number of devices but also lowers the investment cost per unit power of the power plant and reduces the system's footprint.

[0019] 3. During energy storage or release, the heat generated by the oil system and electrical equipment is absorbed by the circulating water through the oil-water heat exchanger and water-water heat exchanger. The water, after absorbing heat (becoming hot water), returns to the hot water tank for storage via the sixth valve. This recovered heat can be used to heat the air during subsequent start-up preheating or energy release, achieving closed-loop recovery and reuse of low-grade waste heat. This avoids the energy waste caused by traditional cooling towers directly releasing heat into the atmosphere, significantly improving the overall energy utilization efficiency of the system.

[0020] 4. This invention integrates the cooling functions of the oil circuit and electrical equipment into the existing fully closed-loop circulating water circuit. This water circuit uses softened demineralized water as the circulating working fluid, ensuring high water purity. Compared to the traditional solution that uses ordinary industrial water (raw water) and an open cooling tower for heat dissipation, this invention completely avoids the scaling and corrosion problems of heat exchange equipment caused by high water hardness and impurities. This extends the service life of oil-water heat exchangers, water-water heat exchangers, and related pipelines, reduces the frequency of equipment cleaning, maintenance, and replacement, and significantly lowers the long-term operation and maintenance costs of the power plant.

[0021] 5. The system of this invention is an optimization of the existing compressed air energy storage power station water circuit system. Therefore, this invention can not only be directly applied to newly built compressed air energy storage power stations, but also achieve technological upgrades through low-cost modification of the pipelines and valves of existing power stations, and has broad industrial application prospects. Attached Figure Description

[0022] The accompanying drawings, which form part of this invention, are used to provide a further understanding of the invention. The illustrative embodiments and descriptions of the invention are used to explain the invention and do not constitute an undue limitation of the invention. In the drawings: Figure 1 A schematic diagram of the structure of the compressed air energy storage system with a fully closed circulating water circuit as described in the embodiment of the present invention; Figure 2 A schematic diagram of the compressed air energy storage system described in the embodiment of the present invention when it is in the oil tank preheating mode; Figure 3 A schematic diagram of the compressed air energy storage system in energy storage mode according to an embodiment of the present invention; Figure 4 This is a schematic diagram of the compressed air energy storage system in the energy release mode according to an embodiment of the present invention.

[0023] Explanation of reference numerals in the attached diagram: 1. Electric motor; 2. Compressor; 3. Energy storage heat exchanger; 4. Gas storage device; 5. Energy release heat exchanger; 6. Expander; 7. Generator; 8. Hot water tank; 9. Hot water pump; 10. Cold water tank; 11. Cold water pump; 12. Oil-water heat exchanger; 13. Water-water heat exchanger; 14. Oil tank; 15. First valve; 16. Second valve; 17. Third valve; 18. Fourth valve; 19. Fifth valve; 20. Sixth valve; 21. Seventh valve. Detailed Implementation

[0024] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and do not constitute a limitation thereof.

[0025] It should be noted that, unless otherwise specified, the embodiments and features described in the present invention can be combined with each other.

[0026] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicating orientations or positional relationships based on the orientations or positional relationships shown in the accompanying drawings, are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation on this invention. Furthermore, the terms "first," "second," etc., 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, features defined with "first," "second," etc., may explicitly or implicitly include one or more of that feature. In the description of this invention, unless otherwise stated, "a plurality of" means two or more.

[0027] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art will understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0028] The invention will now be described in detail with reference to the accompanying drawings and embodiments.

[0029] like Figure 1As shown, this invention provides a compressed air energy storage system with a fully closed-loop circulating water circuit, including a motor 1, a compressor 2, an energy storage heat exchanger 3, an air storage device 4, an energy release heat exchanger 5, an expander 6, a generator 7, a hot water tank 8, a hot water pump 9, a cold water tank 10, a cold water pump 11, an oil-water heat exchanger 12, a water-water heat exchanger 13, and an oil tank 14; wherein, the output shaft of the motor 1 is connected to the input shaft of the compressor 2, the outlet of the compressor 2 is connected to the high-temperature side inlet of the energy storage heat exchanger 3, the high-temperature side outlet of the energy storage heat exchanger 3 is connected to the inlet of the air storage device 4, and the outlet of the air storage device 4 is connected to... The low-temperature inlet of the energy release heat exchanger 5 is connected to the inlet of the expander 6, and the outlet of the expander 6 is connected to the generator 7. The low-temperature outlet of the energy storage heat exchanger 3 is connected to the inlet of the hot water tank 8, and the outlet of the hot water tank 8 is connected to the inlet of the hot water pump 9. The outlet of the hot water pump 9 is divided into two paths: one path is connected to the high-temperature inlet of the energy release heat exchanger 5 through the first valve 15, and the other path is connected to the water-side inlet of the oil-water heat exchanger 12 through the second valve 16. The high-temperature outlet of the energy release heat exchanger 5 is divided into two paths: one path is connected to the inlet of the cold water tank 10, and the other path is connected to the inlet of the cold water tank 10. The outlet of water tank 10 is connected to the inlet of cold water pump 11. The outlet of cold water pump 11 is divided into two paths. One path of the outlet of cold water pump 11 is connected to the low-temperature side inlet of energy storage heat exchanger 3 through the third valve 17. The other path of the outlet of cold water pump 11 is divided into two paths after passing through the second valve 16. One path is connected to the water side inlet of oil-water heat exchanger 12, and the other path is connected to the primary water side inlet of water-water heat exchanger 13 through the fifth valve 19. The other path of the high-temperature side outlet is divided into two paths after passing through the fourth valve 18. One path is connected to the water side inlet of oil-water heat exchanger 12, and the other path is connected to the water-water heat exchanger 13 through the fifth valve 19. The primary water-side inlet of the oil-water heat exchanger 12 is connected to the inlet of the hot water tank 8 via the sixth valve 20, and the other via the seventh valve 21 is connected to the inlet of the cold water tank 10. The oil-side inlet of the oil-water heat exchanger 12 is connected to the outlet of the oil tank 14, and the oil-side outlet of the oil-water heat exchanger 12 is connected to the inlet of the oil tank 14. The primary water-side outlet of the water-water heat exchanger 13 is connected to the inlet of the hot water tank 8, the secondary water-side inlet of the water-water heat exchanger 13 is connected to the outlet of the cooling circuit of the electrical equipment, and the secondary water-side outlet of the water heat exchanger 13 is connected to the inlet of the cooling circuit of the electrical equipment.

[0030] Both hot water pump 9 and cold water pump 11 are variable frequency pumps, providing flow rate as needed.

[0031] The fifth valve 19, the sixth valve 20, and the seventh valve 21 are all regulating valves. By controlling the opening of the regulating valves, the flow rate can be adaptively adjusted.

[0032] The first valve 15, the second valve 16, the third valve 17, and the fourth valve 18 are all on / off valves, which only serve to open or close the pipeline.

[0033] The oil tank 14 includes a lubricating oil tank and / or a fire-resistant oil tank. The lubricating oil is used for the lubrication and cooling of components such as bearings and gearboxes, while the fire-resistant oil is used to drive the actuators of equipment such as the main air valve.

[0034] Electrical equipment includes, but is not limited to, motor frequency converters, generator stators, and other equipment.

[0035] The compressed air energy storage system includes three operating modes: oil tank preheating mode, energy storage mode, and energy release mode.

[0036] like Figure 2 As shown, the working process of the compressed air energy storage system in the oil tank preheating mode is as follows: Before starting compressor 2 and / or expander 6, close valves 15, 17, 18, 19, and 20, and open valves 16 and 21. Hot water in hot water tank 8 enters the high-temperature side of oil-water heat exchanger 12 via hot water pump 9 and valve 16, heating oil tank 14 and becoming cold water, which then enters cold water tank 10 via valve 21. When the oil temperature in oil tank 14 reaches the temperature threshold, start compressor 2 and / or expander 6.

[0037] This invention utilizes hot water stored in the hot water tank 8 to preheat the oil tank 14 (containing lubricating oil and fire-resistant oil) before the compressor 2 or expander 6 starts, via the oil-water heat exchanger 12. The flow rate of the hot water is precisely controlled by the seventh valve 21, allowing the oil temperature to quickly reach the allowable starting conditions. This design replaces the traditional preheating method that relies on a built-in electric heater in the oil tank, avoiding the consumption of external electrical energy, reducing the plant's power consumption in the compressed air energy storage power station, and improving the overall operational economy of the system.

[0038] like Figure 3 As shown, the workflow of the compressed air energy storage system in energy storage mode is as follows: Close the seventh valve 21, the fourth valve 18, and the first valve 15, and open the second valve 16, the third valve 17, the fifth valve 19, and the sixth valve 20.

[0039] Electric motor 1 drives compressor 2 to generate high-temperature and high-pressure air, which enters the high-temperature side of energy storage heat exchanger 3.

[0040] The cold water in the cold water tank 10 is divided into three streams after passing through the cold water pump 11. The first stream of cold water enters the low-temperature side of the energy storage heat exchanger 3 through the third valve 17, cools the high-temperature and high-pressure air, and then enters the hot water tank 8. The high-temperature and high-pressure air is cooled to normal temperature and high-pressure air and then enters the gas storage device 4 for storage. The second stream of cold water enters the water side of the oil-water heat exchanger 12 through the second valve 16, cools the oil tank 14, and then becomes hot water, which enters the hot water tank 8 through the sixth valve 20. The third stream of cold water enters the primary water side of the water-water heat exchanger 13 through the second valve 16 and the fifth valve 19, cools the electrical equipment, and then becomes hot water, which enters the hot water tank 8.

[0041] The temperature of the lubricating oil and / or fire-resistant oil in the oil tank 14 is controlled by adjusting the opening of the seventh valve 21.

[0042] like Figure 4 As shown, the workflow of the compressed air energy storage system in the energy release mode is as follows: Close the second valve 16, the third valve 17 and the seventh valve 21, and open the first valve 15, the sixth valve 20, the fourth valve 18, the fifth valve 19 and the sixth valve 20.

[0043] The ambient temperature high-pressure air in the gas storage device 4 enters the low-temperature side of the energy release heat exchanger 5. The hot water in the hot water tank 8 enters the high-temperature side of the energy release heat exchanger 5 via the hot water pump 9 and the first valve 15. After heating the ambient temperature high-pressure air, it becomes cold water and is divided into two streams. One stream of cold water enters the cold water tank 10, and the other stream of cold water is divided into two streams after passing through the fourth valve 18. One stream of cold water enters the water side of the oil-water heat exchanger 12, cools the oil tank 14, and becomes hot water, which then enters the hot water tank 8 via the sixth valve 20. The other stream of cold water enters the primary water side of the water-water heat exchanger 13, cools the electrical equipment, and then becomes hot water, which enters the hot water tank 8. The ambient temperature high-pressure air in the energy release heat exchanger 5 is heated and becomes high-temperature high-pressure air, which enters the expander 6 to do work and drive the generator 7 to generate electricity.

[0044] In both energy storage and energy release modes, the temperature of the lubricating oil and / or fire-resistant oil in the oil tank 14 is controlled by adjusting the opening of the sixth valve 20, and the temperature of the electrical equipment is controlled by adjusting the opening of the fifth valve 19.

[0045] This invention incorporates regulating valves on the water-side outlet pipe of the oil-water heat exchanger 12, tailored to different operating conditions (seventh valve 21 for heating and sixth valve 20 for cooling). By adjusting the valve opening, the system back pressure is altered, thereby precisely controlling the flow of hot or cold water through the oil-water heat exchanger 12. This design eliminates the reliance on simple on / off switching of the inlet-side valves (second valve 16 and fourth valve 18) for oil temperature control. Instead, continuous and stable flow regulation is achieved through the outlet regulating valves, ensuring precise control of the oil temperature within the target range under various operating conditions and improving system reliability.

[0046] This invention, through the switching of the second valve 16 and the fourth valve 18, introduces cooling water supplied by the cold water pump 11 or the energy release heat exchanger 5 during the energy storage and release processes into the oil-water heat exchanger and the water-water heat exchanger, respectively, for cooling the oil circuit system and large electrical equipment. This system utilizes the existing main circulating water circuit for heat storage / exchange, simultaneously completing the functions of oil circuit cooling and equipment cooling, eliminating the need for additional independent circulating cooling towers, cooling water pumps, and supporting pipelines. This not only reduces the number of devices but also lowers the investment cost per unit power of the power plant and reduces the system's footprint.

[0047] During energy storage or release, the heat generated by the operation of the oil system and electrical equipment is absorbed by the circulating water through the oil-water heat exchanger 12 and the water-water heat exchanger 13. The water that has absorbed the heat (becomes hot water) returns to the hot water tank 8 for storage through the sixth valve 20. This recovered heat can be used to heat the air during subsequent start-up preheating or energy release, realizing closed-loop recovery and reuse of low-grade waste heat. This avoids the energy waste caused by traditional cooling towers directly discharging heat into the atmosphere, and significantly improves the overall energy utilization efficiency of the system.

[0048] The heat exchange medium in the oil-water heat exchanger 12 and the water-water heat exchanger 13 is softened demineralized water, ensuring high water purity. Compared to traditional solutions that use ordinary industrial water (raw water) and independent cooling circuits with open cooling towers, this invention completely avoids scaling and corrosion problems in heat exchange equipment caused by high water hardness and numerous impurities. This extends the service life of the oil-water heat exchanger 12, the water-water heat exchanger 13, and related pipelines, reduces the frequency of equipment cleaning, maintenance, and replacement, and significantly lowers the long-term operation and maintenance costs of the power plant.

[0049] The system of this invention is an optimization of the existing compressed air energy storage power station water circuit system. Therefore, this invention can not only be directly applied to newly built compressed air energy storage power stations, but also achieve technological upgrades through low-cost modification of the pipelines and valves of existing power stations, and has broad industrial application prospects.

[0050] It should be understood that the various forms of processes shown above can be used to reorder, add, or delete steps. For example, the steps described in this invention disclosure can be executed in parallel, sequentially, or in different orders, as long as the desired result of the technical solution disclosed in this invention can be achieved, and this is not limited herein.

[0051] The specific embodiments described above do not constitute a limitation on the scope of protection of this invention. Those skilled in the art should understand that various modifications, combinations, sub-combinations, and substitutions can be made according to design requirements and other factors. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the scope of protection of this invention.

Claims

1. A compressed air energy storage system with a fully closed-loop circulating water circuit, characterized in that, This includes electric motors, compressors, energy storage heat exchangers, gas storage devices, energy release heat exchangers, expanders, generators, hot water tanks, hot water pumps, cold water tanks, cold water pumps, oil-water heat exchangers, water-water heat exchangers, and oil tanks; among which, The output shaft of the electric motor is connected to the input shaft of the compressor, the outlet of the compressor is connected to the high-temperature side inlet of the energy storage heat exchanger, the high-temperature side outlet of the energy storage heat exchanger is connected to the inlet of the gas storage device, the outlet of the gas storage device is connected to the low-temperature side inlet of the energy release heat exchanger, the low-temperature side outlet of the energy release heat exchanger is connected to the inlet of the expander, and the outlet of the expander is connected to the generator. The low-temperature outlet of the energy storage heat exchanger is connected to the inlet of the hot water tank, and the outlet of the hot water tank is connected to the inlet of the hot water pump. The outlet of the hot water pump is divided into two paths: one path is connected to the high-temperature inlet of the energy release heat exchanger through the first valve, and the other path is connected to the water-side inlet of the oil-water heat exchanger through the second valve. The high-temperature outlet of the energy release heat exchanger is divided into two paths. One path of the high-temperature outlet is connected to the inlet of the cold water tank, and the outlet of the cold water tank is connected to the inlet of the cold water pump. The outlet of the cold water pump is also divided into two paths. One path of the cold water pump outlet is connected to the low-temperature inlet of the energy storage heat exchanger through the third valve, and the other path of the cold water pump outlet is divided into two paths after passing through the second valve. One path is connected to the water-side inlet of the oil-water heat exchanger, and the other path is connected to the primary water-side inlet of the water-water heat exchanger through the fifth valve. The other path of the high-temperature outlet is divided into two paths after passing through the fourth valve. One path is connected to the water-side inlet of the oil-water heat exchanger, and the other path is connected to the primary water-side inlet of the water-water heat exchanger through the fifth valve. The water-side outlet of the oil-water heat exchanger is divided into two paths: one path is connected to the inlet of the hot water tank through the sixth valve, and the other path is connected to the inlet of the cold water tank through the seventh valve. The oil-side inlet of the oil-water heat exchanger is connected to the outlet of the oil tank, and the oil-side outlet of the oil-water heat exchanger is connected to the inlet of the oil tank. The primary water-side outlet of the water-to-water heat exchanger is connected to the inlet of the hot water tank, the secondary water-side inlet of the water-to-water heat exchanger is connected to the outlet of the cooling circuit of the electrical equipment, and the secondary water-side outlet of the water heat exchanger is connected to the inlet of the cooling circuit of the electrical equipment.

2. The compressed air energy storage system with a fully closed circulating water circuit according to claim 1, characterized in that, Both the hot water pump and the cold water pump are variable frequency pumps.

3. The compressed air energy storage system with a fully closed circulating water circuit according to claim 1, characterized in that, The fifth, sixth, and seventh valves are all regulating valves, while the first, second, third, and fourth valves are all on / off valves.

4. The compressed air energy storage system with a fully closed circulating water circuit according to claim 1, characterized in that, The heat exchange medium in both oil-water heat exchangers and water-water heat exchangers is demineralized water.

5. The compressed air energy storage system with a fully closed circulating water circuit according to claim 1, characterized in that, The oil tank includes a lubricating oil tank and / or a fire-resistant oil tank.

6. The compressed air energy storage system with a fully closed circulating water circuit according to claim 1, characterized in that, Electrical equipment includes motor frequency converters and / or generator stators.

7. The compressed air energy storage system with a fully closed circulating water circuit according to claim 1, characterized in that, Includes three operating modes: Fuel tank preheating mode: Before starting the compressor and / or expander, close the first, third, fourth, fifth, and sixth valves, and open the second and seventh valves; the hot water in the hot water tank enters the high-temperature side of the oil-water heat exchanger through the second valve after being pumped by the hot water pump, and after heating the oil tank, it becomes cold water and enters the cold water tank through the seventh valve; when the oil temperature in the oil tank reaches the temperature threshold, start the compressor and / or expander. Energy storage operating mode: Close valves 7, 4, and 1; open valves 2, 3, 5, and 6. An electric motor drives a compressor to generate high-temperature, high-pressure air, which then enters the high-temperature side of the energy storage heat exchanger. The cold water in the cold water tank is divided into three streams by the cold water pump. The first stream of cold water enters the low-temperature side of the energy storage heat exchanger through the third valve, cools the high-temperature and high-pressure air, and then enters the hot water tank. The high-temperature and high-pressure air is cooled to room temperature and high-pressure air and then enters the gas storage device for storage. The second stream of cold water enters the water side of the oil-water heat exchanger through the second valve, cools the oil tank, and then becomes hot water, which enters the hot water tank through the sixth valve. The third stream of cold water enters the primary water side of the water-water heat exchanger through the second and fifth valves, cools the electrical equipment, and then becomes hot water, which enters the hot water tank. Energy release operating mode: Close the second, third, and seventh valves, and open the first, sixth, fourth, fifth, and sixth valves; The ambient temperature high-pressure air in the gas storage device enters the low-temperature side of the energy release heat exchanger; Hot water from the hot water tank enters the high-temperature side of the energy release heat exchanger via a hot water pump and the first valve. After heating the ambient temperature high-pressure air, it becomes cold water and is divided into two streams. One stream of cold water enters the cold water tank, while the other stream of cold water is divided into two streams via the fourth valve. One stream of cold water enters the water side of the oil-water heat exchanger, cools the oil tank, and then becomes hot water, which enters the hot water tank via the sixth valve. The other stream of cold water enters the primary water side of the water-water heat exchanger, cools the electrical equipment, and then becomes hot water, which enters the hot water tank. The ambient temperature high-pressure air in the energy release heat exchanger is heated to become high-temperature high-pressure air, which enters the expander to do work and drive the generator to generate electricity.

8. The compressed air energy storage system with a fully closed circulating water circuit according to claim 7, characterized in that, In the oil tank preheating mode, the temperature of the lubricating oil and / or fire-resistant oil in the oil tank is controlled by adjusting the opening of the seventh valve.

9. The compressed air energy storage system with a fully closed circulating water circuit according to claim 7, characterized in that, In both energy storage and energy release modes, the temperature of the lubricating oil and / or fire-resistant oil in the tank is controlled by adjusting the opening of the sixth valve, and the temperature of the electrical equipment is controlled by adjusting the opening of the fifth valve.

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