A compressed water energy storage device with stable pressure and its control method

Abstract

The present invention discloses a compressed water energy storage device for stabilizing pressure and its control method. The device includes a waste heat utilization heat exchanger, a steam compressor, a heat exchanger, an expansion turbine, a heat storage tank, a high-pressure water storage tank, a hydraulic turbine, a low-pressure water storage tank, and a booster pump. The method adopts a combined configuration of devices such as a waste heat utilization heat exchanger, a steam compressor, a heat exchanger, and an expansion turbine, which can achieve efficient recovery and storage of low-temperature waste heat. The temperature of the available waste heat resource can be 25-150 °C, and the system can maximally raise it to about 300 °C, thereby improving the system efficiency. The present invention can solve problems such as peak shaving and energy storage in the prior art.

Description

Technical Field

[0001] The present invention relates to a peak shaving energy storage device and its control method, and particularly to a compressed water energy storage device for stabilizing pressure and its control method. Background Art

[0002] Energy storage technology is one of the key research directions in the future energy field. Existing energy storage technologies include pumped hydro energy storage, compressed air energy storage, and electrochemical energy storage, etc. However, pumped hydro energy storage has problems such as terrain limitations; compressed air energy storage has problems such as low energy storage efficiency and low energy density; electrochemical energy storage has problems such as scale level limitations. And the technology of compressed water energy storage devices based on thermophysical energy storage still has some limitations:

[0003] 1. The system is relatively closed-loop, making it difficult to utilize external low-temperature waste heat, resulting in problems such as energy waste and difficulty in improving the energy storage efficiency of the system;

[0004] 2. During the energy storage process of the system, only a water pump is used for storing high-pressure water, and the storage capacity is limited, making it difficult to apply in large-scale scenarios;

[0005] 3. During the energy release process of the system, problems such as pressure drop caused by the release of the working medium in the tank are ignored, and the actual operating efficiency is often low, making it difficult to meet the requirements. Summary of the Invention

[0006] The purpose of the present invention is to provide a compressed water energy storage device for stabilizing pressure and its control method to solve problems such as peak shaving energy storage in the prior art.

[0007] To achieve the above purpose, the present invention adopts the following technical solutions:

[0008] A compressed water energy storage device for stabilizing pressure includes a waste heat utilization heat exchanger, a steam compressor, a heat exchanger, an expansion turbine, a heat storage tank, a high-pressure water storage tank, a hydraulic turbine, a low-pressure water storage tank, and a booster pump;

[0009] The first outlet of the waste heat utilization heat exchanger is connected to the steam compressor, the outlet of the steam compressor is connected to the first inlet of the heat exchanger, the first outlet of the heat exchanger is connected to the expansion turbine, in addition, the first outlet of the heat exchanger is connected to the first inlet of the high-pressure water storage tank, the outlet of the expansion turbine is connected to the first inlet of the waste heat utilization heat exchanger, and the first outlet of the low-pressure water storage tank is also connected to the first inlet of the waste heat utilization heat exchanger;

[0010] The second outlet of the heat exchanger is connected to the first inlet of the heat storage tank, the first outlet of the heat storage tank is connected to the second inlet of the heat exchanger, the second outlet of the heat storage tank is connected to the second inlet of the high-pressure water storage tank, and the first outlet of the high-pressure water storage tank is connected to the second inlet of the heat storage tank;

[0011] The second outlet of the low-pressure water storage tank is connected to the inlet of the booster pump, the outlet of the booster pump is connected to the third inlet of the high-pressure water storage tank, the second outlet of the high-pressure water storage tank is connected to the inlet of the hydraulic turbine, and the outlet of the hydraulic turbine is connected to the inlet of the low-pressure water storage tank.

[0012] A further improvement of the present invention lies in that the first outlet of the heat exchanger is connected to the expansion turbine through the first control valve.

[0013] A further improvement of the present invention lies in that the first outlet of the low-pressure water storage tank is also connected to the first inlet of the waste heat utilization heat exchanger through the second control valve.

[0014] A further improvement of the present invention lies in that the first outlet of the heat storage tank is connected to the second inlet of the heat exchanger through the third control valve.

[0015] A further improvement of the present invention lies in that the second outlet of the heat storage tank is connected to the second inlet of the high-pressure water storage tank through the fourth control valve.

[0016] A further improvement of the present invention lies in that the first outlet of the heat exchanger is connected to the first inlet of the high-pressure water storage tank through the fifth control valve.

[0017] A further improvement of the present invention lies in that the second outlet of the high-pressure water storage tank is connected to the inlet of the hydraulic turbine through the sixth control valve.

[0018] A further improvement of the present invention lies in that the second outlet of the low-pressure water storage tank is connected to the inlet of the booster pump through the seventh control valve.

[0019] A control method for a compressed water energy storage device with stable pressure, which is based on the described compressed water energy storage device with stable pressure, includes:

[0020] When heat storage is required, the first control valve and the third control valve are opened, and the remaining control valves are closed; the low-pressure water absorbs heat and evaporates through the waste heat utilization heat exchanger, turns into water vapor, and then enters the steam compressor to complete compression. After the water vapor is heated and pressurized, it enters the heat exchanger to release heat, transfers the heat to the heat storage medium, and then the water enters the expansion turbine through the first control valve to do work, and then returns to the waste heat utilization heat exchanger to complete the cycle; while the heat storage medium flows out of the heat storage tank, enters the heat exchanger through the third control valve to absorb heat, and then returns to the heat storage tank to achieve heat storage;

[0021] When high-pressure water needs to be stored, open the second control valve, the third control valve, the fifth control valve and the seventh control valve, and close the rest of the control valves; the low-pressure water in the low-pressure water storage tank flows through the waste heat utilization heat exchanger through the second control valve for endothermic evaporation, and then enters the steam compressor to complete compression. After the steam is heated and pressurized, it enters the heat exchanger to release heat. After transferring the heat to the heat storage medium, the water enters the high-pressure water storage tank for storage through the fifth control valve; in addition, the low-pressure water in the low-pressure water storage tank also flows through the seventh control valve to the booster pump and enters the high-pressure water storage tank for storage after being pressurized; similarly, the heat storage medium flows out of the heat storage tank, enters the heat exchanger through the third control valve to absorb heat, and then returns to the heat storage tank to achieve heat storage;

[0022] When energy release is required, open the fourth control valve and the sixth control valve, and close the rest of the control valves; the heat storage medium in the heat storage tank enters the high-pressure water storage tank through the fourth control valve to heat the high-pressure water. The high-pressure water absorbs heat and becomes saturated steam, and part of the high-pressure water is discharged to the hydraulic turbine through the sixth control valve for energy release through work. The water after doing work returns to the low-pressure water storage tank to complete the working process; at this time, since the water storage tank contains saturated water and saturated steam, the temperature in the water storage tank is maintained by adjusting the heating amount to keep the pressure in the tank constant.

[0023] A further improvement of the present invention is that the heat that can be utilized by the waste heat utilization heat exchanger includes industrial waste heat and waste heat, and the temperature is 25-150°C.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1. By adopting a combined configuration of equipment such as a waste heat utilization heat exchanger, a steam compressor, a heat exchanger, and an expansion turbine, high-efficiency recovery and storage of low-temperature waste heat can be achieved. The temperature of the available waste heat resources can be 25-150°C, and the system can increase it to about 300°C at most, thereby improving the system efficiency;

[0026] 2. Adding a low-pressure water storage tank, a heat exchanger, a steam compressor, a heat exchanger and a high-pressure water storage tank loop in the system can compress water through the steam compressor to obtain high-pressure water, further improving the ability to store high-pressure water;

[0027] 3. Setting up a heat storage tank and a high-pressure water storage tank, and heating the high-pressure water storage tank with the heat in the heat storage tank, the stable pressure output of the high-pressure water can be realized through the gas-liquid phase change principle of water, so as to ensure that the cycle pressure will not be reduced due to the release of the working medium during the energy release process of the system, and further improve the system operation efficiency. Brief Description of the Drawings

[0028] Figure 1 It is a schematic diagram of a compressed water energy storage device with stable pressure according to the present invention.

[0029] Description of the reference numerals:

[0030] 1. Waste heat utilization heat exchanger, 2. Steam compressor, 3. Heat exchanger, 4. Expansion turbine, 5. Heat storage tank, 6. High-pressure water storage tank, 7. Hydraulic turbine, 8. Low-pressure water storage tank, 9. Booster pump, 101. First control valve, 102. Second control valve, 103. Third control valve, 104. Fourth control valve, 105. Fifth control valve, 106. Sixth control valve, 107. Seventh control valve. Detailed implementation manners

[0031] The implementation manners of the present invention will be described in detail below with reference to the accompanying drawings.

[0032] Please refer to Figure 1 As described above, a compressed water energy storage device for stabilizing pressure provided by the present invention includes: a waste heat utilization heat exchanger 1, a steam compressor 2, a heat exchanger 3, an expansion turbine 4, a heat storage tank 5, a high-pressure water storage tank 6, a hydraulic turbine 7, a low-pressure water storage tank 8, and a booster pump 9. In addition, it further includes a first control valve 101, a second control valve 102, a third control valve 103, a fourth control valve 104, a fifth control valve 105, a sixth control valve 106, and a seventh control valve 107.

[0033] The first outlet of the waste heat utilization heat exchanger 1 is connected to the steam compressor 2, the outlet of the steam compressor 2 is connected to the first inlet of the heat exchanger 3, the first outlet of the heat exchanger 3 is connected to the expansion turbine 4 through the first control valve 101. In addition, the first outlet of the heat exchanger 3 is also connected to the first inlet of the high-pressure water storage tank 6 through the fifth control valve 105. The outlet of the expansion turbine 4 is connected to the first inlet of the waste heat utilization heat exchanger 1, and the first outlet of the low-pressure water storage tank 8 is also connected to the first inlet of the waste heat utilization heat exchanger 1 through the second control valve 102.

[0034] The second outlet of the heat exchanger 3 is connected to the first inlet of the heat storage tank 5, the first outlet of the heat storage tank 5 is connected to the second inlet of the heat exchanger 3 through the third control valve 103, the second outlet of the heat storage tank 5 is connected to the second inlet of the high-pressure water storage tank 6 through the fourth control valve 104, and the first outlet of the high-pressure water storage tank 6 is connected to the second inlet of the heat storage tank 5.

[0035] The second outlet of the low-pressure water storage tank 8 is connected to the inlet of the booster pump 9 through the seventh control valve 107, the outlet of the booster pump 9 is connected to the third inlet of the high-pressure water storage tank 6, the second outlet of the high-pressure water storage tank 6 is connected to the inlet of the hydraulic turbine 7 through the sixth control valve 106, and the outlet of the hydraulic turbine 7 is connected to the inlet of the low-pressure water storage tank 8.

[0036] A control method for a compressed water energy storage device for stabilizing pressure includes:

[0037] When heat storage is required, the first control valve 101 and the third control valve 103 are opened, and the rest of the control valves are closed. Low-pressure water absorbs heat and evaporates through the waste heat utilization heat exchanger 1, turning into water vapor. Then it enters the water vapor compressor 2 to complete compression. The water vapor after temperature and pressure increase enters the heat exchanger 3 to release heat. After transferring the heat to the heat storage medium, the water enters the expansion turbine 4 through the first control valve 101 to do work, and then returns to the waste heat utilization heat exchanger 1 to complete the cycle. The heat storage medium flows out of the heat storage tank 5, enters the heat exchanger 3 through the third control valve 103 to absorb heat, and then returns to the heat storage tank 5 to achieve heat storage.

[0038] When high-pressure water storage is required, the second control valve 102, the third control valve 103, the fifth control valve 105, and the seventh control valve 107 are opened, and the rest of the control valves are closed. The low-pressure water in the low-pressure water storage tank 8 flows through the waste heat utilization heat exchanger 1 through the second control valve 102 to absorb heat and evaporate. Then it enters the water vapor compressor 2 to complete compression. The water vapor after temperature and pressure increase enters the heat exchanger 3 to release heat. After transferring the heat to the heat storage medium, the water enters the high-pressure water storage tank 6 for storage through the fifth control valve 105. In addition, the low-pressure water in the low-pressure water storage tank 8 also flows to the booster pump 9 through the seventh control valve 107, and after pressure increase, it enters the high-pressure water storage tank 6 for storage. Similarly, the heat storage medium flows out of the heat storage tank 5, enters the heat exchanger 3 through the third control valve 103 to absorb heat, and then returns to the heat storage tank 5 to achieve heat storage.

[0039] When energy release is required, the fourth control valve 104 and the sixth control valve 106 are opened, and the rest of the control valves are closed. The heat storage medium in the heat storage tank 5 enters the high-pressure water storage tank 6 through the fourth control valve 104 to heat the high-pressure water. The high-pressure water absorbs heat and turns into saturated water vapor, and part of the high-pressure water is discharged to the hydraulic turbine 7 through the sixth control valve 106 to do work and release energy. The water after doing work returns to the low-pressure water storage tank 8 to complete the work process. At this time, since the high-pressure water storage tank 6 contains saturated water and saturated water vapor, the temperature in the high-pressure water storage tank 6 can be maintained by adjusting the heating amount to keep the tank pressure constant, improving the working stability.

[0040] Furthermore, the heat that can be utilized by the waste heat utilization heat exchanger 1 includes industrial waste heat, waste heat, etc., and the temperature can be in the range of 25 - 150°C.

[0041] This method can achieve: absorbing low-valley electricity to store energy during low electricity consumption periods and releasing energy during high electricity consumption periods, realizing peak shaving and valley filling of electricity and having a high energy storage efficiency.

[0042] The specific advantages are as follows:

[0043] 1. By adopting a combined configuration of equipment such as a waste heat utilization heat exchanger, a water vapor compressor, a heat exchanger, and an expansion turbine, high-efficiency recovery and storage of low-temperature waste heat can be achieved;

[0044] 2. Adding a low-pressure water storage tank, a heat exchanger, a steam compressor, a heat exchanger, and a high-pressure water storage tank loop within the system can further enhance the ability to store high-pressure water.

[0045] 3. Setting up a heat storage tank and a high-pressure water storage tank, and using the heat in the heat storage tank to heat the water storage tank can achieve a stable output of high-pressure water through the principle of gas-liquid phase change of water, improving the operating efficiency of the system.

[0046] In summary, the present invention provides a compressed water energy storage device for stabilizing pressure and its control method, which can efficiently achieve thermoelectric storage and conversion, is less restricted by terrain, etc., and can also be adjusted according to user needs to reduce the user's electricity cost.

[0047] The above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art can still modify or equivalently replace the specific implementation manners of the present invention. Any such modifications or equivalent replacements that do not depart from the spirit and scope of the present invention are within the scope of the claims of the present invention pending approval.

Claims

1. A compressed water energy storage device with stable pressure, characterized in that, it includes a waste heat utilization heat exchanger, a steam compressor, a heat exchanger, an expansion turbine, a heat storage tank, a high-pressure water storage tank, a hydraulic turbine, a low-pressure water storage tank and a booster pump; The first outlet of the waste heat utilization heat exchanger is connected to the steam compressor, the outlet of the steam compressor is connected to the first inlet of the heat exchanger, the first outlet of the heat exchanger is connected to the expansion turbine, in addition, the first outlet of the heat exchanger is connected to the first inlet of the high-pressure water storage tank, the outlet of the expansion turbine is connected to the first inlet of the waste heat utilization heat exchanger, and the first outlet of the low-pressure water storage tank is also connected to the first inlet of the waste heat utilization heat exchanger; The second outlet of the heat exchanger is connected to the first inlet of the heat storage tank, the first outlet of the heat storage tank is connected to the second inlet of the heat exchanger, the second outlet of the heat storage tank is connected to the second inlet of the high-pressure water storage tank, and the first outlet of the high-pressure water storage tank is connected to the second inlet of the heat storage tank; The second outlet of the low-pressure water storage tank is connected to the inlet of the booster pump, the outlet of the booster pump is connected to the third inlet of the high-pressure water storage tank, the second outlet of the high-pressure water storage tank is connected to the inlet of the hydraulic turbine, and the outlet of the hydraulic turbine is connected to the inlet of the low-pressure water storage tank.

2. A compressed water energy storage device with stable pressure according to claim 1, characterized in that, the first outlet of the heat exchanger is connected to the expansion turbine through a first control valve.

3. A compressed water energy storage device with stable pressure according to claim 2, characterized in that, the first outlet of the low-pressure water storage tank is also connected to the first inlet of the waste heat utilization heat exchanger through a second control valve.

4. A compressed water energy storage device with stable pressure according to claim 3, characterized in that, the first outlet of the heat storage tank is connected to the second inlet of the heat exchanger through a third control valve.

5. A compressed water energy storage device with stable pressure according to claim 4, characterized in that, the second outlet of the heat storage tank is connected to the second inlet of the high-pressure water storage tank through a fourth control valve.

6. A compressed water energy storage device with stable pressure according to claim 5, characterized in that, the first outlet of the heat exchanger is connected to the first inlet of the high-pressure water storage tank through a fifth control valve.

7. A compressed water energy storage device with stable pressure according to claim 6, characterized in that, the second outlet of the high-pressure water storage tank is connected to the inlet of the hydraulic turbine through a sixth control valve.

8. A compressed water energy storage device with stable pressure according to claim 7, characterized in that, the second outlet of the low-pressure water storage tank is connected to the inlet of the booster pump through a seventh control valve.

9. A control method for a compressed water energy storage device with stable pressure, characterized in that, this method is based on a compressed water energy storage device with stable pressure according to claim 8, and includes: When heat storage is required, the first control valve and the third control valve are opened, and the rest of the control valves are closed; low-pressure water absorbs heat and evaporates through the waste heat utilization heat exchanger, turning into water vapor, which then enters the steam compressor to complete compression. After the water vapor is heated and pressurized, it enters the heat exchanger to release heat, transferring the heat to the heat storage medium. Then, the water enters the expansion turbine through the first control valve to do work and then returns to the waste heat utilization heat exchanger to complete the cycle; the heat storage medium flows out of the heat storage tank, enters the heat exchanger through the third control valve to absorb heat, and then returns to the heat storage tank to achieve heat storage. When high-pressure water storage is required, the second control valve, the third control valve, the fifth control valve, and the seventh control valve are opened, and the rest of the control valves are closed; the low-pressure water in the low-pressure water storage tank flows through the waste heat utilization heat exchanger through the second control valve for heat absorption and evaporation, and then enters the steam compressor to complete compression. After the water vapor is heated and pressurized, it enters the heat exchanger to release heat, transferring the heat to the heat storage medium. Then, the water enters the high-pressure water storage tank through the fifth control valve for storage; in addition, the low-pressure water in the low-pressure water storage tank also flows through the seventh control valve to the booster pump and enters the high-pressure water storage tank for storage after being pressurized; similarly, the heat storage medium flows out of the heat storage tank, enters the heat exchanger through the third control valve to absorb heat, and then returns to the heat storage tank to achieve heat storage. When energy release is required, the fourth control valve and the sixth control valve are opened, and the rest of the control valves are closed; the heat storage medium in the heat storage tank enters the high-pressure water storage tank through the fourth control valve to heat the high-pressure water. The high-pressure water absorbs heat and turns into saturated water vapor, and part of the high-pressure water is discharged to the hydraulic turbine through the sixth control valve for work and energy release. The water after doing work returns to the low-pressure water storage tank to complete the work process; at this time, since the water storage tank contains saturated water and saturated water vapor, the temperature in the water storage tank is maintained by adjusting the heating amount to keep the pressure in the tank constant.

10. The control method of a compressed water energy storage device for stabilizing pressure according to claim 9, characterized in that, The heat that can be utilized by the waste heat utilization heat exchanger includes industrial waste heat and waste heat, with a temperature range of 25 - 150 °C.

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