Method and system for using high-pressure water as a working medium for high-temperature compressed air energy storage and heat exchange

Abstract

The present invention provides a method and system for using high-pressure water as a heat storage medium for high-temperature compressed air. The method comprises an air compression unit and an air turbine. The nitrogen delivery unit outputs nitrogen at a pressure that is 10°C lower than the air compression unit outlet temperature and corresponds to any saturated vapor pressure of water vapor within the air compression unit outlet temperature range. The energy storage and release unit comprises a first heat exchanger having a shell-side inlet connected to the air compression unit via a pipeline, a shell-side outlet connected to a gas storage device via a pipeline, a tube-side inlet connected to a low-temperature water storage tank via a pipeline, and a tube-side outlet connected to a high-temperature water storage tank via a pipeline. The low-temperature water storage tank is connected to the nitrogen delivery unit via a pipeline. A second heat exchanger having a tube-side inlet connected to the high-temperature water storage tank via a pipeline, a tube-side outlet connected to the low-temperature water storage tank via a pipeline, a shell-side inlet connected to the gas storage device via a pipeline, and a shell-side outlet connected to the air turbine via a pipeline. This invention reduces both system complexity and investment in heat storage mediums.

Description

Technical Field

[0001] The present invention relates to the field of energy technology, and specifically to a method and system for utilizing high-pressure water as a working medium for energy storage and heat exchange of high-temperature compressed air. Background Art

[0002] The large-capacity advanced adiabatic compressed air energy storage system has many advantages such as large energy storage capacity, long energy release time, high system efficiency, fast startup speed, strong adjustment capability, zero fuel consumption, and zero pollution emissions. It can play a key role in alleviating the expansion of transmission lines, shaving peak power loads, and large-scale absorption of new energy electricity, and ensure the safe and stable operation of the power grid.

[0003] The workflow of advanced adiabatic compressed air energy storage not only includes the compression and expansion of air, but is also accompanied by the recovery and utilization of compression heat. Specifically: when storing energy, the compressor compresses the air while also increasing the temperature of the air. The high-temperature air passes through the compression side heat exchanger before entering the air storage chamber, and is cooled by the cold fluid before being stored in the air storage chamber; at the same time, the cold fluid is heated and converted into hot fluid and stored in the hot tank. This process realizes the decoupled storage of pressure potential energy and compression heat energy. When releasing energy, the compressed air is introduced into the turbine to perform work, and is heated by the hot fluid before entering the turbine, thereby increasing its work capacity in the air turbine; at the same time, the hot fluid is cooled and stored in the cold tank to be heated again when compressed next time. This process realizes the coupled power generation of pressure potential energy and compression heat energy. The specific compression and expansion as well as heat storage and heat exchange processes are as follows: Figure 1 shown.

[0004] Therefore, the recovery, storage, and utilization of compression heat are crucial components of the workflow of advanced adiabatic compressed air energy storage systems, significantly impacting system efficiency. Currently, there are two viable heat storage and exchange technology approaches for compressed air energy storage systems with large-capacity engineering properties: medium-temperature heat storage and exchange technology and high-temperature heat storage and exchange technology. These different heat storage and exchange technology approaches influence the choice of heat storage and exchange fluids, the cost of heat storage and exchange equipment, and the composition of the heat storage and exchange system.

[0005] For medium-temperature heat storage and exchange technology, the compressor unit is usually composed of four compressors in series, so that within the pressure bearing capacity of the natural gas storage chamber (about 10MPa), the outlet temperature of each compressor is about 200℃. Taking a heat exchange end difference of 10℃, the maximum temperature of the heat storage medium is about 190℃. According to the physical properties of water and water vapor, choosing high-pressure water of about 2MPa as the heat storage medium will not cause water vaporization, and 2MPa high-pressure water is the heat storage medium commonly used in the current medium-temperature scheme. The heat storage system consists of a compression side heat exchanger group, an expansion side heat exchanger group, high and low temperature storage tanks, and a nitrogen pressure stabilizing device, such as Figure 1The 300MW compressed air energy storage demonstration power station in Yingcheng, Hubei Province, utilizes this medium-temperature heat storage and exchange technology. This system is relatively simple and requires relatively low investment. Compared to the medium-temperature heat storage and exchange technology, the high-temperature solution utilizes a higher heat storage and exchange temperature, resulting in a higher system efficiency of 74%, 4 percentage points higher than the medium-temperature solution.

[0006] For high-temperature heat storage and exchange technology, the compressor unit is usually composed of three sections in series, and the outlet temperature of each compressor is about 340℃, so 2MPa high-pressure water cannot be selected as the heat storage and exchange medium. The 60MW compressed air energy storage power station in Jintan Salt Cavern in Jiangsu Province uses thermal oil as the heat storage and exchange medium. Its compression, expansion and heat storage and exchange system is as follows: Figure 1 While using thermal oil can achieve high-temperature heat storage and exchange, the investment in the heat storage and exchange fluid increases dozens of times. Therefore, due to its high cost, thermal oil is not suitable as a heat storage and exchange fluid for larger-capacity (300MW and above) compressed air energy storage.

[0007] At present, the 300MW-class compressed air energy storage power station with high-temperature solution uses a combination of high-pressure water and molten salt as the storage and heat exchange working medium. The heat exchange process is completed in two stages: molten salt is used for heat exchange above 180°C; 2MPa high-pressure water is used for heat exchange below 180°C. In this way, the high-pressure water will not vaporize due to overheating, and the molten salt will not solidify due to overcooling. In addition, the storage of hot and cold high-pressure water and hot and cold molten salt is separated from each other and does not interfere with each other. The compression, expansion and storage and heat exchange processes are as follows: Figure 2 Compared with thermal oil, the combination of molten salt and 2MPa high-pressure water can significantly reduce the investment in heat storage and exchange fluids, but it increases equipment investment and system complexity.

[0008] Therefore, it is of great significance to design a method and device that can significantly reduce the investment in heat storage and exchange fluids without increasing the complexity of the system. Summary of the Invention

[0009] In view of the shortcomings of the existing technology, the purpose of the present invention is to provide a method and system for using high-pressure water as a high-temperature compressed air energy storage and heat exchange medium, aiming to solve the problems raised in the technical background and significantly reduce the investment in storage and heat exchange mediums while reducing the complexity of the system.

[0010] To solve the above technical problems, the present invention provides a first implementation solution, which is a system that uses high-pressure water as a working medium for high-temperature compressed air energy storage and heat exchange. The system includes an air compression unit and an air turbine. The air compression unit compresses air and outputs high-temperature air during peak electricity consumption periods. The system also includes:

[0011] The output nitrogen pressure of the nitrogen delivery unit is any saturated vapor pressure corresponding to water vapor in the temperature range from 10°C lower than the outlet temperature of the air compression unit to the outlet temperature of the air compression unit;

[0012] The energy storage and release unit includes a first heat exchanger, a gas storage device, a second heat exchanger, a low-temperature water storage tank, and a high-temperature water storage tank, wherein:

[0013] The first heat exchanger is used to exchange heat and store energy between the high-temperature air output by the air compression unit and the low-temperature liquid working medium. The shell-side inlet of the first heat exchanger is connected to the air compression unit via a pipeline, the shell-side outlet is connected to the air storage device via a pipeline, the tube-side inlet is connected to the low-temperature water storage tank via a pipeline, and the tube-side outlet is connected to the high-temperature water storage tank via a pipeline;

[0014] The low-temperature water storage tank is connected to the nitrogen delivery unit through a pipeline, and is used to inject air and pressurize the first heat exchanger so that the pressure of the low-temperature water storage tank and the pressure of the first heat exchanger are consistent with the pressure of the nitrogen delivery unit, and the high-temperature air at the outlet of the air compression unit is cooled at this pressure;

[0015] The second heat exchanger is used to exchange heat and release energy between the low-temperature air in the gas storage device and the high-temperature liquid working medium in the high-temperature water storage tank. Its tube-side inlet is connected to the high-temperature water storage tank through a pipeline, the tube-side outlet is connected to the low-temperature water storage tank through a pipeline, the shell-side inlet is connected to the gas storage device through a pipeline, and the shell-side outlet is connected to the air turbine through a pipeline. The high-temperature water storage tank is connected to the nitrogen delivery unit through a pipeline, which is used to inject gas and pressurize the second heat exchanger so that the pressure of the high-temperature water storage tank and the pressure of the second heat exchanger are consistent with the pressure of the nitrogen delivery unit.

[0016] Preferably, a cold water circulation pump is provided on the pipeline connecting the liquid inlet of the first heat exchanger to the low-temperature water storage tank, a hot water circulation pump is provided on the pipeline connecting the liquid inlet of the second heat exchanger to the high-temperature water storage tank, and a main steam regulating combined valve is provided on the pipeline connecting the outlet of the second heat exchanger to the air turbine.

[0017] Preferably, the nitrogen delivery unit includes a nitrogen compressor and a nitrogen delivery main pipe, the nitrogen delivery main pipe is provided with a first pressure gauge, the nitrogen compressor is connected to the nitrogen delivery main pipe through a pipeline and a nitrogen control valve, the nitrogen delivery main pipe is connected to the low-temperature water storage tank and the high-temperature water storage tank through pipelines, and the nitrogen delivery main pipe is also provided with a nitrogen delivery main pipe pressure relief valve.

[0018] Preferably, the air compression unit comprises an electric motor and an air compressor, the electric motor and the air compressor are coaxially connected, the air compressor is connected to the shell side inlet of the first heat exchanger through a pipeline, and the air turbine is coaxially connected to a generator.

[0019] Preferably, all the pipelines are provided with control valves.

[0020] Preferably, the low-temperature water storage tank and the high-temperature water storage tank are both provided with a nitrogen injection door, a second pressure gauge, a safety valve and a vent valve. The low-temperature water storage tank is connected to the cold water main pipe through a first delivery branch pipe, and the high-temperature water storage tank is connected to the hot water main pipe through a second delivery branch pipe. The first delivery branch pipe is provided with a low-temperature water tank filling and drainage valve, and the second delivery branch pipe is provided with a high-temperature water tank filling and drainage valve. The pipe-side inlet of the first heat exchanger is connected to the cold water main pipe through a pipeline, the pipe-side inlet of the second heat exchanger is connected to the hot water main pipe through a pipeline, the pipe-side outlet of the second heat exchanger is connected to the cold water main pipe through a pipeline, and the pipe-side outlet of the first heat exchanger is connected to the hot water main pipe through a pipeline. An exhaust valve is also provided on the first heat exchanger and the second heat exchanger.

[0021] The second implementation scheme provided by the present invention is to provide a method for using high-pressure water as a working medium for high-temperature compressed air energy storage and heat exchange. The method is based on a system using high-pressure water as a working medium for high-temperature compressed air energy storage and heat exchange, and includes the following steps:

[0022] The external water injection equipment fills the low-temperature water storage tank with water. When the water level in the low-temperature water storage tank is reached, the cold water circulation pump is started to inject the cold water in the low-temperature water storage tank into the pipe side of the first heat exchanger until the water level in the first heat exchanger reaches the design value;

[0023] The external water injection equipment fills the high-temperature water storage tank with water. When the water level in the high-temperature water storage tank reaches the water level, the hot water circulation pump is started to send the hot water in the high-temperature water storage tank into the pipe side of the second heat exchanger until the water level in the first heat exchanger can realize the hot water circulation pump circulation;

[0024] Start the nitrogen compressor to pressurize nitrogen and then inject it into the nitrogen delivery main pipe. The nitrogen pressure is the pressure value corresponding to water vapor 10°C lower than the outlet temperature of the air compressor. The nitrogen delivery main pipe delivers nitrogen to the low-temperature water storage tank and the high-temperature water storage tank through pipelines respectively, so as to adjust the pressure values ​​of the first heat exchanger and the second heat exchanger respectively and make their pressure values ​​the same;

[0025] Driven by an electric motor, the air compressor compresses air from the atmosphere and sends it into the shell side of the first heat exchanger through a pipeline to exchange heat with the cold water in the tube side of the first heat exchanger. The heat of the hot air is stored and then sent to the high-temperature water storage tank through a pipeline for energy storage. The high-temperature air after heat exchange becomes low-temperature air and is stored in the gas storage device. When releasing energy, the hot water in the high-temperature water storage tank is sent into the tube side of the second heat exchanger through a hot water circulation pump to exchange heat with the low-temperature air sent into the shell side of the second heat exchanger by the gas storage device. The low-temperature air absorbs heat and becomes high-temperature air, which is then sent to the air turbine to drive the generator to rotate, so as to output electrical energy during peak hours of electricity consumption.

[0026] Preferably, when the outlet temperature of the air compression unit is 340°C, the pressure of the nitrogen output by the nitrogen delivery unit is any value of the saturated vapor pressure corresponding to water vapor at 330°C to 340°C.

[0027] Preferably, the nitrogen pressure is 14 MPa.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The method and device proposed by the present invention utilizes high-pressure water as a heat exchange medium for high-temperature compressed air energy storage. Compared to existing technologies, this method and device can significantly reduce the investment in energy storage and heat exchange mediums while reducing system complexity. Specifically, the present invention uses any saturated vapor pressure corresponding to water vapor in a temperature range from 10°C below the outlet temperature of the air compression unit to the outlet temperature of the air compression unit as the nitrogen pressure of the nitrogen delivery unit. The nitrogen is then delivered to the low-temperature water storage tank, a first heat exchanger, a second heat exchanger, and a high-temperature water storage tank via the nitrogen delivery unit, ensuring that the pressures of the low-temperature water storage tank, the first heat exchanger, the high-temperature water storage tank, and the second heat exchanger are all consistent with the pressure of the nitrogen delivery unit. When the compressed air is exchanged for heat and energy, the first heat exchanger uses high-temperature water at the same pressure as the nitrogen as the heat storage and exchange medium in the high-temperature scheme compressed air energy storage system. Compared to the molten salt and 2MPa high-pressure water commonly used as the heat storage and exchange medium in the high-temperature scheme, the method and device do not require cold and hot molten salt storage tanks or molten salt heat exchangers, greatly simplifying the process flow of the heat storage and exchange system and reducing the complexity of the system operation. In addition, the system provided by the present invention increases the pressure of the heat storage and exchange system by first injecting water and then injecting gas to increase pressure, avoiding the use of a high-power water pump. There is no need to overcome the static pressure difference, only the resistance to fluid flow needs to be overcome, thereby reducing the initial investment in the heat storage and exchange medium and the entire project. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 This is a schematic diagram of the process of air compression and expansion, as well as compression heat recovery, storage and utilization based on thermal oil or 2MPa high-pressure water.

[0031] Figure 2 Schematic diagram of the process of air compression and expansion, as well as compression heat recovery, storage and utilization based on a combination of molten salt and 2MPa high-pressure water.

[0032] Figure 3 The figure is a schematic diagram of the process flow of air compression and expansion and compression heat recovery, storage and utilization based on 14MPa high-pressure water in the present invention.

[0033] Description of reference numerals:

[0034] 1. Electric motor; 2. Air compressor; 3. First heat exchanger; 4. Air storage device; 5. Second heat exchanger; 6. Main steam regulating combined valve; 7. Air turbine; 8. Generator; 9. Low-temperature water storage tank; 10. Cold water circulation pump; 11. High-temperature water storage tank; 12. Hot water circulation pump; 13. Nitrogen compressor; 14. First pressure gauge; 15. Nitrogen control valve; 16. Nitrogen main pipe pressure relief valve; 17. Second pressure gauge; 18. Nitrogen injection valve; 19. Vent valve; 20. Safety valve; 21. Low-temperature water tank filling and drainage valve; 22. High-temperature water tank filling and drainage valve; 23. First water outlet valve; 24. Valve from the turbine side heat exchanger outlet to the low-temperature water main pipe; 25. Exhaust valve. DETAILED DESCRIPTION

[0035] In order to make the above-mentioned purposes, features and advantages of the embodiments of the present invention more obvious and easy to understand, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0036] The inventors discovered that the physical properties of water and water vapor show that when the pressure increases, the saturation temperature of water increases. As shown in Table 1, under standard atmospheric pressure (0.101325MPa), the saturation temperature of water is 100°C; when the pressure increases to 1.55MPa, the saturation temperature is 200°C, which is equal to the outlet temperature of the compressor of the medium-temperature scheme. In theory, it can serve as a heat storage and exchange working fluid. In engineering, 2MPa high-pressure water is selected, which leaves a larger vaporization margin. When the pressure continues to rise to 14.6MPa, the corresponding saturation temperature is 340°C, which reaches the outlet temperature of the compressor of the high-temperature scheme. If the heat exchange end difference is 10°C, the temperature of the high-pressure water is 330°C, and the corresponding saturation pressure is 12.86MPa. Considering a certain vaporization margin, any high-pressure water between 12.86MPa and 14.0MPa can be selected as the heat storage and exchange working fluid of the high-temperature scheme compressed air energy storage system.

[0037] Table 1 Water saturation temperature and pressure

[0038]

[0039]

[0040] In view of this, the present invention provides a method and system for using high-pressure water as a high-temperature compressed air energy storage and heat exchange medium, aiming to solve the problems raised in the technical background and significantly reduce the investment in energy storage and heat exchange medium on the basis of reducing the complexity of the system.

[0041] like Figure 3As shown, the present invention provides a system that uses high-pressure water as a working medium for high-temperature compressed air energy storage and heat exchange, including an air compression unit and an air turbine 7. The air compression unit compresses air and outputs high-temperature air during peak power consumption, and also includes:

[0042] The output nitrogen pressure of the nitrogen delivery unit is any saturated vapor pressure corresponding to water vapor in the temperature range from 10°C lower than the outlet temperature of the air compression unit to the outlet temperature of the air compression unit;

[0043] The energy storage and release unit includes a first heat exchanger 3, a gas storage device 4, a second heat exchanger 5, a low-temperature water storage tank 9 and a high-temperature water storage tank 11, wherein:

[0044] The first heat exchanger 3 is used to perform heat exchange and energy storage between the high-temperature air output by the air compression unit and the low-temperature liquid working medium. The shell-side inlet of the first heat exchanger 3 is connected to the air compression unit via a pipeline, the shell-side outlet of the first heat exchanger 3 is connected to the air storage device 4 via a pipeline, the tube-side inlet of the first heat exchanger 3 is connected to the low-temperature water storage tank 9 via a pipeline, and the tube-side outlet of the first heat exchanger 3 is connected to the high-temperature water storage tank 11 via a pipeline.

[0045] The low-temperature water storage tank 9 is connected to the nitrogen delivery unit through a pipeline, and is used to inject gas and pressurize the first heat exchanger 3 so that the pressure of the low-temperature water storage tank 9 and the first heat exchanger 3 are consistent with the pressure of the nitrogen delivery unit, and the high-temperature air at the outlet of the air compression unit is cooled at this pressure;

[0046] The second heat exchanger 5 is used to exchange heat and release energy between the low-temperature air in the gas storage device 4 and the high-temperature liquid working medium in the high-temperature water storage tank 11. The tube-side inlet of the second heat exchanger 5 is connected to the high-temperature water storage tank 11 through a pipeline, and the tube-side outlet of the second heat exchanger 5 is connected to the low-temperature water storage tank 9 through a pipeline. The shell-side inlet of the second heat exchanger 5 is connected to the gas storage device 4 through a pipeline, and the shell-side outlet of the second heat exchanger 5 is connected to the air turbine 7 through a pipeline.

[0047] Specifically, the high-temperature water storage tank 11 is connected to the nitrogen delivery unit through a pipeline, and is used to inject gas and pressurize the second heat exchanger 5 so that the pressure of the high-temperature water storage tank 11 and the second heat exchanger 5 are consistent with the pressure of the nitrogen delivery unit.

[0048] Specifically, a cold water circulation pump 10 is provided on the pipeline connecting the liquid inlet of the first heat exchanger 3 and the low-temperature water storage tank 9, a hot water circulation pump 12 is provided on the pipeline connecting the liquid inlet of the second heat exchanger 5 and the high-temperature water storage tank 11, and a main steam regulating combined valve 6 is provided on the pipeline connecting the outlet of the second heat exchanger 5 and the air turbine 7.

[0049] The purpose of regulating valve 6 is to regulate the air intake and thereby control the output power of air turbine 7. Without valve 6, the power output of air turbine 7 will be uncontrolled.

[0050] Specifically, without adding an additional high-pressure water pump, only a small amount of high-pressure nitrogen is used to pressurize and stabilize the heat storage and exchange system. This can significantly reduce the investment in heat storage and exchange fluids while reducing the complexity of the system. This is because the water pressure of the system is very high. If a water supply pump with corresponding parameters is configured, the equipment investment will increase. The nitrogen delivery unit includes a nitrogen compressor 13 and a nitrogen delivery main pipe. The nitrogen delivery main pipe is provided with a first pressure gauge 14. The nitrogen compressor 13 is connected to the nitrogen delivery main pipe through a pipeline and a nitrogen control valve 15. The nitrogen delivery main pipe is connected to the low-temperature water storage tank 9 and the high-temperature water storage tank 11 through pipelines. The nitrogen delivery main pipe is also provided with a nitrogen delivery main pipe pressure relief valve 16. When the nitrogen delivery main pipe pressure is higher than the specified value, the nitrogen delivery main pipe pressure relief valve 16 opens to ensure that the nitrogen delivery main pipe is not over-pressurized.

[0051] Specifically, the air compression unit includes an electric motor 1 and an air compressor 2, which are coaxially connected. The air compressor 2 is connected to the shell side inlet of the first heat exchanger 3 through a pipeline, and the air turbine 7 is coaxially connected to the generator 8.

[0052] The motor 1 and the air compressor 2 are coaxially connected, and the air turbine 7 is coaxially connected to the generator 8, in order to reduce the number of speed change gear boxes, lower equipment investment, and reduce the complexity of the shaft system.

[0053] Specifically, all pipelines are equipped with control valves.

[0054] Specifically, the low-temperature water storage tank 9 and the high-temperature water storage tank 11 are both provided with a nitrogen injection door 18, a second pressure gauge 17, a safety valve 20 and a vent valve 19. The low-temperature water storage tank 9 is connected to the cold water main pipe through a first delivery branch pipe, and the high-temperature water storage tank 11 is connected to the hot water main pipe through a second delivery branch pipe. A low-temperature water tank filling and drainage valve 21 is provided on the first delivery branch pipe, and a high-temperature water tank filling and drainage valve 22 is provided on the second delivery branch pipe. The pipe side inlet of the first heat exchanger 3 is connected to the cold water main pipe through a pipeline, the pipe side inlet of the second heat exchanger 5 is connected to the hot water main pipe through a pipeline, the pipe side outlet of the second heat exchanger 5 is connected to the cold water main pipe through a pipeline, and the pipe side outlet of the first heat exchanger 3 is connected to the hot water main pipe through a pipeline. An exhaust valve 25 is also provided on the first heat exchanger 3 and the second heat exchanger 5.

[0055] When the compressor is operating, water in the low-temperature water tank 9 enters the first heat exchanger 3 through the low-temperature water tank filling and drainage valve 21. After being heated, it enters the high-temperature water tank 11 for storage through the high-temperature water tank filling and drainage valve 22. When the air turbine 7 is operating, water in the high-temperature water tank 11 enters the second heat exchanger 5 through the high-temperature water tank filling and drainage valve 22. After being cooled, it enters the low-temperature water tank 9 through the low-temperature water tank filling and drainage valve 21 for storage.

[0056] The present invention provides a method for using high-pressure water as a working medium for high-temperature compressed air energy storage and heat exchange. The method is based on a system using high-pressure water as a working medium for high-temperature compressed air energy storage and heat exchange, and includes the following steps:

[0057] The external water injection device injects water into the low-temperature water storage tank 9. When the water level in the low-temperature water storage tank 9 is reached, the cold water circulation pump 10 is started to inject the cold water in the low-temperature water storage tank 9 into the pipe side of the first heat exchanger 3 until the water level in the first heat exchanger 3 reaches the design value.

[0058] The external water injection device fills the high-temperature water storage tank 11 with water. When the water level in the high-temperature water storage tank 11 is reached, the hot water circulation pump 12 is started to send the hot water in the high-temperature water storage tank 11 into the pipe side of the second heat exchanger 5 until the water level in the first heat exchanger 3 can realize the circulation of the hot water circulation pump 12;

[0059] Start the nitrogen compressor 13 to pressurize the nitrogen and inject it into the nitrogen delivery main pipe. The nitrogen pressure is the pressure value corresponding to the water vapor 10°C lower than the outlet temperature of the air compressor 2. The nitrogen delivery main pipe delivers the nitrogen to the low-temperature water storage tank 9 and the high-temperature water storage tank 11 through pipelines, respectively, to adjust the pressure values ​​of the first heat exchanger 3 and the second heat exchanger 5 respectively and make their pressure values ​​the same;

[0060] Driven by the electric motor 1, the air compressor 2 compresses the air from the atmosphere and sends it into the shell side of the first heat exchanger 3 through a pipeline to exchange heat with the cold water in the tube side of the first heat exchanger 3. The heat of the hot air is stored and then sent to the high-temperature water storage tank 11 through a pipeline for energy storage. The high-temperature air after heat exchange becomes low-temperature air and is stored in the gas storage device 4. When releasing energy, the hot water in the high-temperature water storage tank 11 is sent into the tube side of the second heat exchanger 5 through the hot water circulation pump 12 to exchange heat with the low-temperature air sent into the shell side of the second heat exchanger 5 by the gas storage device 4. After the low-temperature air absorbs heat and becomes high-temperature air, it is sent to the air turbine 7 to drive the generator 8 to rotate, which is used to output electrical energy during peak power consumption hours.

[0061] Specifically, when the outlet temperature of the air compression unit is 340° C., the pressure of the nitrogen gas output by the nitrogen delivery unit is any value of the saturated vapor pressure corresponding to water vapor at 330° C. to 340° C.

[0062] The physical properties of water and water vapor indicate that the saturation temperature of water increases as pressure rises. As shown in Table 1, at standard atmospheric pressure (0.101325 MPa), the saturation temperature of water is 100°C. When the pressure rises to 1.55 MPa, the saturation temperature reaches 200°C, which is equal to the outlet temperature of the compressor in the medium-temperature solution. In theory, it serves as a heat storage medium. However, in engineering, high-pressure water at 2 MPa is selected, which allows for a larger vaporization margin. When the pressure continues to rise to 14.6 MPa, the corresponding saturation temperature is 340°C, reaching the outlet temperature of the compressor in the high-temperature solution. With a heat exchange end difference of 10°C, the high-pressure water temperature is 330°C, and the corresponding saturation pressure is 12.86 MPa. Considering a certain vaporization margin, an arbitrary value for the saturated vapor pressure of water vapor between 330°C and 340°C is selected.

[0063] Preferably, the nitrogen pressure is 14 MPa, which can ensure that water does not vaporize after being heated to a high temperature state and has a certain vaporization margin.

[0064] The present invention provides a specific embodiment. In this embodiment, 14MPa nitrogen is used to pressurize and stabilize the entire heat storage and exchange system. The working principle is as follows:

[0065] 1. System water injection and pressurization process

[0066] Before the system works, water injection and pressurization operations are required to increase the water side pressure of the heat storage and exchange system to the rated value.

[0067] First, water is injected into the first heat exchanger 3 , the low-temperature water storage tank 9 , the second heat exchanger 5 , and the high-temperature water storage tank 11 .

[0068] (1) Filling the first heat exchanger 3 and the low-temperature water storage tank 9 with water

[0069] Before injecting water, open the vent door 19 of the low-temperature water storage tank 9 and the exhaust valve 25 of the first heat exchanger 3; open the filling and drainage valve 21 of the low-temperature water tank, and inject water from the external water injection equipment into the low-temperature water storage tank 9 through the first delivery branch pipe from the cold water main pipe. When the water level reaches the starting condition of the cold water circulation pump 10, start the cold water circulation pump 10, inject water into the first heat exchanger 3, keep the water outlet valve 23 of the first heat exchanger 3 closed, wait until water appears in the exhaust valve 25 of the first heat exchanger 3, close the exhaust valve 25, stop the cold water circulation pump 10, wait until the liquid level of the low-temperature water storage tank 9 rises to the design value, close the vent door 19 of the low-temperature water storage tank 9, and the water injection of the first heat exchanger 3 and the low-temperature water storage tank 9 is completed.

[0070] (2) Filling the second heat exchanger 5 and the high-temperature water storage tank 11 with water

[0071] Before injecting water, open the vent door 19 of the high-temperature water storage tank 11 and the exhaust valve 25 of the second heat exchanger 5; open the high-temperature water tank filling and drainage valve 22, and the external water injection equipment injects water into the high-temperature water storage tank 11 from the hot water main pipe through the second delivery branch pipe. When the water level reaches the starting condition of the hot water circulation pump 12, start the hot water circulation pump 12, and inject water into the second heat exchanger 5. Keep the water outlet valve 23 of the second heat exchanger 5 closed. When water appears in the exhaust valve 25 of the second heat exchanger 5, close the exhaust valve 25, stop the hot water circulation pump 12, and wait until the liquid level in the high-temperature water storage tank 11 reaches a level that allows the hot water circulation pump 12 to circulate. Close the vent door 19 of the high-temperature water storage tank 11, and the water injection into the second heat exchanger 5 and the high-temperature water storage tank 11 is completed.

[0072] Secondly, gas is injected into the first heat exchanger 3, the low-temperature water storage tank 9, the second heat exchanger 5, and the high-temperature water storage tank 11. Before injecting gas, the nitrogen compressor 13 must be started to inject gas into the nitrogen main pipe. The first pressure gauge 14 pressure measuring point controls the opening of the nitrogen control valve 15 to maintain the nitrogen main pipe pressure at 14 MPa.

[0073] (1) Injecting gas into the first heat exchanger 3 and the low-temperature water storage tank 9

[0074] The nitrogen injection valve 18 of the cryogenic water storage tank 9 is opened, and the cryogenic water tank filling and draining valve 21 is kept open to pressurize the first heat exchanger 3 and the cryogenic water storage tank 9. The second pressure gauge 17 of the cryogenic water storage tank 9 measures the pressure and controls the pressure in the cryogenic water storage tank 9 to be maintained at 14 MPa. Because the cryogenic water storage tank 9 is directly connected to the first heat exchanger 3, when the pressure in the cryogenic water storage tank 9 is maintained at 14 MPa, the pressure in the first heat exchanger 3 is also 14 MPa. When the cryogenic water storage tank 9 is overpressured, the safety valve 20 of the cryogenic water storage tank 9 automatically opens.

[0075] (2) Gas injection into the second heat exchanger 5 and the high-temperature water storage tank 11

[0076] The nitrogen injection valve 18 of the high-temperature water storage tank 11 is opened, and the high-temperature water tank filling and drainage valve 22 is kept open. The second heat exchanger 5 and the high-temperature water storage tank 11 are pressurized. The second pressure gauge 17 of the high-temperature water storage tank 11 measures the pressure and controls the pressure in the high-temperature water storage tank 11 to be maintained at 14 MPa. Because the high-temperature water storage tank 11 is directly connected to the second heat exchanger 5, when the pressure in the high-temperature water storage tank 11 is maintained at 14 MPa, the pressure in the second heat exchanger 5 is also 14 MPa. When the high-temperature water storage tank 11 is overpressured, the safety valve 20 of the high-temperature water storage tank 11 automatically opens.

[0077] After gas injection, the pressures in the first heat exchanger 3, low-temperature water tank 9, second heat exchanger 5, and high-temperature water tank 11 are all equal, at 14 MPa. Therefore, the head of the cold water circulation pump 10 and the hot water circulation pump 10 only needs to be sufficient to meet the water flow resistance losses and does not need to be too high. Since the pressures in the first heat exchanger 3, low-temperature water tank 9, second heat exchanger 5, and high-temperature water tank 11 are equal, there is no need to overcome static pressure differences; only the resistance to fluid flow, which includes both longitudinal and local resistance, needs to be overcome. This reduces energy consumption and investment.

[0078] 2. System energy storage and release workflow

[0079] During energy storage, the motor 1 drives the air compressor 2 to rotate and compress the air from the atmosphere; the high-temperature and high-pressure air generated at about 340°C is stored in the low-temperature water storage tank 9 in the shell side of the first heat exchanger 3 and sent into the 14MPa high-pressure cold water in the pipe side of the first heat exchanger 3 by the cold water circulation pump 10 for cooling. After cooling, the low-temperature air is collected into the air storage device 4 (the air storage device 4 is the air storage chamber) through the high-pressure air main pipe; after heat exchange, the temperature of the high-pressure cold water increases and becomes high-pressure hot water, and the thermal energy of the high-temperature air is stored in the high-temperature water storage tank 11 for energy storage.

[0080] During energy release, the low-temperature, high-pressure air in air storage device 4 (i.e., the air storage chamber) is released and heated in the shell side of second heat exchanger 5 by 14 MPa high-pressure hot water stored in high-temperature water tank 11 and delivered to the tube side of second heat exchanger 5 by hot water circulation pump 12. The low-temperature air is heated to 320°C, then enters air turbine 7 through main steam regulating combined valve 6, where it expands and generates work, driving synchronous generator 8 to output electricity during peak hours. The high-pressure cold water after heat exchange is then stored in low-temperature water tank 9, where it is used to recover the heat of compression when the compressor is operating.

[0081] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such modifications and variations of the present invention fall within the scope of the claims and their equivalents, the present invention is intended to include such modifications and variations.

Claims

1. A system using high-pressure water as a working medium for high-temperature compressed air energy storage and heat exchange, comprising an air compression unit and an air turbine (7), characterized in that: The air compression unit compresses air and outputs high-temperature air during peak electricity consumption, and further comprises: The nitrogen delivery unit has an output nitrogen pressure that is 10°C lower than the saturated steam pressure of water vapor at the outlet of the air compression unit; The energy storage and release unit comprises a first heat exchanger (3), a gas storage device (4), a second heat exchanger (5), a low-temperature water storage tank (9) and a high-temperature water storage tank (11), wherein: A first heat exchanger (3) is used for heat exchange and energy storage between the high-temperature air output by the air compression unit and the low-temperature liquid working medium, wherein the shell-side inlet is connected to the air compression unit via a pipeline, the shell-side outlet is connected to the air storage device (4) via a pipeline, the tube-side inlet is connected to the low-temperature water storage tank (9) via a pipeline, and the tube-side outlet is connected to the high-temperature water storage tank (11) via a pipeline; The low-temperature water storage tank (9) is connected to the nitrogen delivery unit through a pipeline, and is used to inject gas and pressurize the first heat exchanger (3), so that the pressure of the low-temperature water storage tank (9) and the pressure of the first heat exchanger (3) are consistent with the pressure of the nitrogen delivery unit, and the high-temperature air at the outlet of the air compression unit is cooled at this pressure; The second heat exchanger (5) is used for heat exchange and energy release between the low-temperature air in the gas storage device (4) and the high-temperature liquid working medium in the high-temperature water storage tank (11). The tube-side inlet is connected to the high-temperature water storage tank (11) through a pipeline, the tube-side outlet is connected to the low-temperature water storage tank (9) through a pipeline, the shell-side inlet is connected to the gas storage device (4) through a pipeline, and the shell-side outlet is connected to the air turbine (7) through a pipeline. The high-temperature water storage tank (11) is connected to the nitrogen delivery unit through a pipeline, and is used for gas injection and pressurization of the second heat exchanger (5) so that the pressure of the high-temperature water storage tank (11) and the pressure of the second heat exchanger (5) are consistent with the pressure of the nitrogen delivery unit.

2. The system for utilizing high-pressure water as a high-temperature compressed air energy storage and heat exchange medium according to claim 1 is characterized in that: A cold water circulation pump (10) is provided on the pipeline connecting the liquid inlet of the first heat exchanger (3) and the low-temperature water storage tank (9), a hot water circulation pump (12) is provided on the pipeline connecting the liquid inlet of the second heat exchanger (5) and the high-temperature water storage tank (11), and a main steam regulating combined valve (6) is provided on the pipeline connecting the outlet of the second heat exchanger (5) and the air turbine (7).

3. The system for utilizing high-pressure water as a high-temperature compressed air energy storage and heat exchange medium according to claim 1 is characterized in that: The nitrogen delivery unit comprises a nitrogen compressor (13) and a nitrogen delivery main pipe, wherein the nitrogen delivery main pipe is provided with a first pressure gauge (14), the nitrogen compressor (13) is connected to the nitrogen delivery main pipe via a pipeline and a nitrogen control valve (15), the nitrogen delivery main pipe is connected to a low-temperature water storage tank (9) and a high-temperature water storage tank (11) via pipelines, and the nitrogen delivery main pipe is further provided with a nitrogen delivery main pipe pressure relief valve (16).

4. The system for utilizing high-pressure water as a high-temperature compressed air energy storage and heat exchange medium according to claim 1 is characterized in that: The air compression unit comprises an electric motor (1) and an air compressor (2), wherein the electric motor (1) and the air compressor (2) are coaxially connected, the air compressor (2) is connected to the shell-side inlet of the first heat exchanger (3) through a pipeline, and the air turbine (7) is coaxially connected to a generator (8).

5. The system for utilizing high-pressure water as a high-temperature compressed air energy storage and heat exchange medium according to claim 1 is characterized in that: All of the pipelines are equipped with control valves.

6. The system for utilizing high-pressure water as a high-temperature compressed air energy storage and heat exchange medium according to claim 1 is characterized in that: The low-temperature water storage tank (9) and the high-temperature water storage tank (11) are both provided with a nitrogen injection valve (18), a second pressure gauge (17), a safety valve (20), and a vent valve (19). The low-temperature water storage tank (9) is connected to a cold water main pipe via a first delivery branch pipe, and the high-temperature water storage tank (11) is connected to a hot water main pipe via a second delivery branch pipe. A low-temperature water tank injection and drainage valve (21) is provided on the first delivery branch pipe, and a high-temperature water tank injection and drainage valve (22) is provided on the second delivery branch pipe. The pipe-side inlet of the first heat exchanger (3) is connected to the cold water main pipe via a pipeline, the pipe-side inlet of the second heat exchanger (5) is connected to the hot water main pipe via a pipeline, the pipe-side outlet of the second heat exchanger (5) is connected to the cold water main pipe via a pipeline, and the pipe-side outlet of the first heat exchanger (3) is connected to the hot water main pipe via a pipeline. The first heat exchanger (3) and the second heat exchanger (5) are also provided with an exhaust valve (25).

7. A method for using high-pressure water as a high-temperature compressed air energy storage and heat exchange medium, characterized in that: The method is based on the system of claim 6 that uses high-pressure water as a high-temperature compressed air energy storage and heat exchange medium, and includes the following steps: The external water injection device injects water into the low-temperature water storage tank (9), and after the water level of the low-temperature water storage tank (9) is reached, the cold water circulation pump (10) is started to inject the cold water in the low-temperature water storage tank (9) into the pipe side of the first heat exchanger (3) until the water level of the first heat exchanger (3) reaches the design value; The external water injection device injects water into the high-temperature water storage tank (11), and after the water level in the high-temperature water storage tank (11) is reached, the hot water circulation pump (12) is started to send the hot water in the high-temperature water storage tank (11) into the pipe side of the second heat exchanger (5) until the water level in the first heat exchanger (3) can be circulated by the hot water circulation pump (12); The nitrogen compressor (13) is started to pressurize the nitrogen and then inject it into the nitrogen delivery main pipe. The nitrogen pressure is a saturated steam pressure value corresponding to water vapor with a temperature 10°C lower than that of the air compressor (2). The nitrogen delivery main pipe delivers the nitrogen to the low-temperature water storage tank (9) and the high-temperature water storage tank (11) through pipelines, respectively, for adjusting the pressure values ​​of the first heat exchanger (3) and the second heat exchanger (5) respectively, and making their pressure values ​​equal; The air compressor (2) is driven by the electric motor (1) to compress the air from the atmosphere and send it to the shell side of the first heat exchanger (3) through a pipeline to exchange heat with the cold water in the tube side of the first heat exchanger (3). The heat of the hot air is stored and then sent to the high-temperature water storage tank (11) through a pipeline for energy storage. The high-temperature air after heat exchange becomes low-temperature air and is stored in the air storage device (4). When releasing energy, the hot water in the high-temperature water storage tank (11) is sent to the tube side of the second heat exchanger (5) through the hot water circulation pump (12) to exchange heat with the low-temperature air sent to the shell side of the second heat exchanger (5) by the air storage device (4). The low-temperature air absorbs heat and becomes high-temperature air, which is then sent to the air turbine (7) to drive the generator (8) to rotate, so as to output electric energy during peak hours of electricity consumption.

8. The method of using high-pressure water as a high-temperature compressed air energy storage and heat exchange medium according to claim 7, characterized in that: When the outlet temperature of the air compression unit is 340° C., the pressure of the nitrogen gas output by the nitrogen delivery unit is any value of the saturated vapor pressure corresponding to water vapor at 330° C. to 340° C.

9. The method of using high-pressure water as a high-temperature compressed air energy storage and heat exchange medium according to claim 7, characterized in that: The nitrogen pressure is 14 MPa.

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