Nitrogen constant-pressure and constant-pressure pressurized water energy storage system and constant-pressure method

Abstract

The invention relates to the technical field of compressed air energy storage, in particular to a nitrogen constant-pressure and constant-pressure pressurized water energy storage system and a constant-pressure method. The system comprises an energy storage module, a constant-pressure and constant-pressure module and a water replenishing and pressure relief module. The energy storage module comprises a cold water tank, a heat exchange unit and a hot water tank which are connected, and the constant-pressure and constant-pressure module comprises a first pressure measuring instrument on the hot water tank, a nitrogen compressor connected with the cold water tank and the hot water tank and a pressure reducing valve set. The water replenishing and pressure relief module comprises a normal-pressure water tank connected with the cold water tank and a water drainage loop connected with the cold water tank and the normal-pressure water tank, and the pressure measuring unit further comprises a second pressure measuring instrument on the cold water tank. By controlling the nitrogen amount in the hot water tank, the pressure in the hot water tank is kept stable, so that the pressure fluctuation of the system is reduced, the reliability of the system is improved, and the cost of the pressurized water storage tank is effectively reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of compressed air energy storage, and in particular to a nitrogen constant pressure pressurized water energy storage system and a constant pressure method. Background Art

[0002] Energy storage systems have the ability to time-shift energy and respond quickly, and can effectively solve many problems brought about by large-scale access to new energy sources to the power system. Compressed air energy storage systems have the advantages of large capacity, long life, low cost, flexible site selection, and high safety. They are increasingly attracting widespread attention from academia and industry, and have broad application prospects.

[0003] In a compressed air energy storage system, the air temperature at the compressor outlet can reach over 300°C. In order to effectively utilize this compression heat, a compressed air energy storage system is usually equipped with a heat storage system to store this compression heat. In order to reduce the grade loss of compression heat, high-temperature and high-pressure hot water is generally used as the storage medium to store this compression heat, and the hot water temperature is generally 160°C~190°C. Therefore, in order to prevent the hot water in the storage tank from vaporizing, the storage tank needs to maintain a certain nitrogen pressure.

[0004] However, during the charging and discharging process of the pressurized water heat storage system, the pressurized water is constantly heated or cooled, which will cause the temperature of the nitrogen filled in the system to change due to the temperature of the pressurized water, thereby causing the system pressure to fluctuate. Therefore, in order to prevent the system from overpressure, the existing method is to reserve a certain margin for the design pressure of the storage tank. However, this method will cause the design pressure of the storage tank to increase significantly, significantly increasing the cost of the storage tank. Summary of the invention

[0005] The technical problem to be solved by the embodiments of the present invention is to provide a nitrogen constant pressure pressurized water energy storage system and a constant pressure method to solve the problem in the prior art that the method of preventing system overpressure by increasing the design pressure of the storage tank will significantly increase the cost of the storage tank.

[0006] The present invention discloses a nitrogen constant pressure water energy storage system, comprising: An energy storage module, comprising a cold water tank, a heat exchange unit and a hot water tank connected in sequence, wherein the hot water tank is connected to a nitrogen source; A constant pressure and constant pressure module, comprising a pressure measuring unit, a pressurization regulating unit and a decompression regulating unit, wherein the pressure measuring unit comprises a first pressure measuring instrument arranged on the hot water tank, the pressurization regulating unit comprises a pressurization pipeline and a nitrogen compressor, the cold water tank, the nitrogen compressor and the hot water tank are sequentially connected through the pressurization pipeline, the decompression regulating unit comprises a decompression pipeline and a decompression valve group, the hot water tank, the decompression valve group and the cold water tank are sequentially connected through the decompression pipeline; The water replenishment pressure relief module includes a water replenishment unit and a first-level pressure relief unit. The water replenishment unit includes a water replenishment pipeline and a normal-pressure water tank. The normal-pressure water tank is connected to the cold water tank through the water replenishment pipeline. The first-level pressure relief unit includes a water relief circuit connecting the cold water tank and the normal-pressure water tank. The pressure measuring unit also includes a second pressure measuring instrument arranged on the cold water tank.

[0007] Optionally, a first solenoid valve is provided on the pressurizing pipeline between the cold water tank and the nitrogen compressor, a second solenoid valve is provided on the pressurizing pipeline between the hot water tank and the nitrogen compressor, the pressure reducing valve group includes a plurality of independently controlled pressure reducing valves, and the opening of the pressure reducing valve group is associated with the measurement values ​​of the first pressure measuring instrument and the second pressure measuring instrument.

[0008] Optionally, a nitrogen filling point is arranged on the pressurized pipeline between the first solenoid valve and the cold water tank, and the nitrogen filling point is connected to a nitrogen source, so that after the nitrogen is filled from the nitrogen filling point, the filled nitrogen enters the hot water tank and the cold water tank in sequence through the nitrogen compressor, and a third solenoid valve is arranged on the pressurized pipeline between the nitrogen filling point and the cold water tank.

[0009] Optionally, a high-temperature working medium outlet pipeline is connected between the hot water tank and the heat exchange unit, and a regulating valve group is arranged on the high-temperature working medium outlet pipeline, and the regulating valve group includes a plurality of independently controlled regulating valves, so that the high-temperature working medium flows out from the hot water tank through the high-temperature working medium outlet pipeline. A high-temperature working medium introduction pipeline is also connected between the hot water tank and the heat exchange unit, and a first working medium pressure pump is arranged on the high-temperature working medium introduction pipeline, which is used to extract the high-temperature working medium after heat exchange and introduce it into the hot water tank through the high-temperature working medium introduction pipeline; A fourth solenoid valve is provided on the high-temperature working medium introduction pipeline between the first working medium pressure pump and the hot water tank, and a fifth solenoid valve is provided on the high-temperature working medium introduction pipeline between the first working medium pressure pump and the heat exchange unit.

[0010] Optionally, the heat exchange unit includes a common heat exchanger, and a medium flow channel and an air flow channel arranged in the common heat exchanger, a working fluid delivery pipeline is arranged on the cold water tank, and the cold water tank is connected to one end of the medium flow channel through the working fluid delivery pipeline, a sixth solenoid valve is arranged on the working fluid delivery pipeline, and the high-temperature working fluid outlet pipeline and the high-temperature working fluid inlet pipeline are respectively connected to the other end of the medium flow channel; The common heat exchanger is provided with a first air delivery pipe and a second air delivery pipe, wherein the first air delivery pipe is connected to one end of the air flow channel, and the second air delivery pipe is connected to the other end of the air flow channel.

[0011] Optionally, a first temperature measuring instrument and a flow measuring instrument are provided on the first air delivery pipeline, and a second temperature measuring instrument is provided on the second air delivery pipeline. The rotation speed of the first working fluid booster pump and the opening of the regulating valve group are both associated with the measurement values ​​of the first temperature measuring instrument, the flow measuring instrument and the second temperature measuring instrument.

[0012] Optionally, the water make-up unit also includes a second working fluid pressure pump arranged on the water make-up pipeline, a seventh solenoid valve is arranged on the water make-up pipeline between the second working fluid pressure pump and the normal pressure water tank, an eighth solenoid valve is arranged on the water make-up pipeline between the second working fluid pressure pump and the cold water tank, and a ninth solenoid valve is arranged on the drain circuit.

[0013] Optionally, a first liquid level measuring instrument is provided on the cold water tank, and a second liquid level measuring instrument is provided on the hot water tank. The water injection amount of the cold water tank is associated with the measurement values ​​of the first liquid level measuring instrument and the second liquid level measuring instrument, and the rotation speed of the second working fluid booster pump is associated with the measurement value of the first pressure measuring instrument.

[0014] Optionally, the water replenishment pressure relief module further includes a secondary pressure relief unit, and the secondary pressure relief unit includes a first air release valve arranged on the cold water tank and a second air release valve arranged on the hot water tank.

[0015] The present invention also provides a pressure-constant method, using the above-mentioned pressurized water energy storage system, the pressure-constant method comprising: Control the nitrogen source to pressurize and deliver nitrogen to the hot water tank and the cold water tank in sequence through an external compression device, and after the nitrogen filling is completed, control the atmospheric pressure water tank to initially replenish the working medium to the cold water tank; During the heat storage or heat release process of the system, the first pressure measuring instrument is controlled to obtain the pressure value in the hot water tank in real time, and the obtained pressure value of the hot water tank is compared with the standard pressure threshold of the hot water tank. According to the comparison result, the nitrogen compressor is controlled to pressurize the nitrogen in the cold water tank and transport it to the hot water tank, or the pressure reducing valve group is controlled to decompress the nitrogen in the hot water tank and transport it to the cold water tank, until the pressure in the hot water tank remains constant; The second pressure measuring instrument is controlled to obtain the pressure value in the cold water tank in real time. If the obtained pressure value of the cold water tank exceeds the preset first-level pressure value, the low-temperature working fluid in the cold water tank is controlled to be discharged into the normal pressure water tank. If the obtained pressure value of the cold water tank exceeds the preset second-level pressure value, the nitrogen in the cold water tank and the hot water tank is controlled to be discharged to the outside of the environment.

[0016] Compared with the prior art, the nitrogen constant pressure pressurized water energy storage system and constant pressure method provided in the embodiment of the present invention have the following beneficial effects: By setting up an energy storage module consisting of a cold water tank, a heat exchange unit and a hot water tank. During the heat storage process of the system, as the water level in the hot water tank rises, the pressure of the hot water tank will fluctuate; and during the heat release process of the system, as the water level in the hot water tank drops, the pressure of the hot water tank will fluctuate. Therefore, a constant pressure module is set up, and the pressure value in the hot water tank is obtained in real time by the first pressure measuring instrument. When the measured value of the first pressure measuring instrument is lower than the standard pressure lower limit of the hot water tank, the nitrogen compressor is controlled to pressurize the nitrogen in the cold water tank and transport it to the hot water tank. When the measured value of the first pressure measuring instrument is higher than the standard pressure upper limit of the hot water tank, the pressure reducing valve group is controlled to reduce the pressure of the nitrogen in the hot water tank and transport it to the cold water tank, so as to control the amount of nitrogen in the hot water tank to maintain the pressure in the hot water tank stable. Therefore, when the system stores or releases heat, since the pressure in the hot water tank remains stable, the pressure fluctuation of the system is only affected by the volume change of the pressurized water working medium in the cold water tank. Then, a pressure relief module is set. When the pressure in the cold water tank is measured to be overpressure, the low-temperature working medium in the cold water tank only needs to be discharged back to the normal pressure water tank to keep the pressure of the system stable, which greatly reduces the pressure fluctuation of the system and improves the reliability of the system. There is no need to increase the design pressure of the storage tank, which effectively reduces the cost of the pressurized water storage tank. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] The technical solution of the present invention will be further described in detail below with reference to the accompanying drawings and embodiments, in which: Figure 1 A schematic block diagram of the overall structure of a pressurized water energy storage system provided in an embodiment of the present invention.

[0018] The reference numerals in the figures are: 1. Energy storage module; 11. Cold water tank; 111. Working fluid delivery pipeline; 112. Sixth solenoid valve; 113. First liquid level measuring instrument; 114. First air release valve; 12. Heat exchange unit; 121. Common heat exchanger; 122. First air delivery pipeline; 123. Second air delivery pipeline; 124. First temperature measuring instrument; 125. Flow measuring instrument; 126. Second temperature measuring instrument; 13. Hot water tank; 131. High-temperature working fluid outlet pipeline; 132. Regulating valve group; 133. High-temperature working fluid introduction pipeline; 134. First working fluid booster pump; 135. Fourth solenoid valve; 136. The fifth solenoid valve; 137, the second liquid level measuring instrument; 138, the second air release valve; 2, the constant pressure module; 21, the first pressure measuring instrument; 22, the pressurizing pipeline; 221, the first solenoid valve; 222, the second solenoid valve; 223, the nitrogen filling point; 224, the third solenoid valve; 23, the nitrogen compressor; 24, the pressure reducing pipeline; 25, the pressure reducing valve group; 26, the second pressure measuring instrument; 3, the water supply and pressure relief module; 31, the water supply pipeline; 32, the normal pressure water tank; 33, the water discharge circuit; 34, the second working fluid pressurizing pump; 35, the seventh solenoid valve; 36, the eighth solenoid valve; 37, the ninth solenoid valve. DETAILED DESCRIPTION

[0019] It should be noted that, in the absence of conflict, the embodiments and features in the embodiments of the present application can be combined with each other. Now, in conjunction with the accompanying drawings, the preferred embodiments of the present invention are described in detail.

[0020] The present invention discloses a nitrogen constant pressure water energy storage system, such as Figure 1 As shown, it includes an energy storage module 1, a constant pressure and constant pressure module 2 and a water replenishment and pressure relief module 3. The energy storage module 1 includes a heat exchange pipeline, and a cold water tank 11, a heat exchange unit 12 and a hot water tank 13 connected by the heat exchange pipeline, and the hot water tank 13 is connected to a nitrogen source. The constant pressure and constant pressure module 2 includes a pressure measuring unit, a pressure adjustment unit and a pressure reduction adjustment unit, and the pressure measuring unit includes a first pressure measuring instrument 21 arranged on the hot water tank 13. The pressure adjustment unit includes a pressurization pipeline 22 and a nitrogen compressor 23, and the cold water tank 11, the nitrogen compressor 23 and the hot water tank 13 are connected in sequence through the pressurization pipeline 22. The pressure reduction adjustment unit includes a pressure reduction pipeline 24 and a pressure reduction valve group 25, and the hot water tank 13, the pressure reduction valve group 25 and the cold water tank 11 are connected in sequence through the pressure reduction pipeline 24. The water replenishment and pressure relief module 3 includes a water replenishment unit and a primary pressure relief unit. The water replenishment unit includes a water replenishment pipeline 31 and a normal pressure water tank 32. The normal pressure water tank 32 is connected to the cold water tank 11 through the water replenishment pipeline 31. The primary pressure relief unit includes a water relief circuit 33 connecting the cold water tank 11 and the normal pressure water tank 32. The pressure measurement unit also includes a second pressure measuring instrument 26 arranged on the cold water tank 11.

[0021] Through the implementation of the above-mentioned pressurized water energy storage system embodiment, an energy storage module 1 consisting of a cold water tank 11, a heat exchange unit 12 and a hot water tank 13 is provided. The atmospheric pressure water tank 32 usually stores low-temperature pressurized water working medium, and the atmospheric pressure water tank 32 injects low-temperature pressurized water working medium into the cold water tank 11 through the water supply pipeline 31, so as to compress the compressed air passing through the heat exchange unit 12 for heat energy storage. That is, when the system stores heat, the low-temperature working medium injected into the cold water tank 11 exchanges heat with the compressed air flowing through the heat exchange unit 12, and then enters the hot water tank 13 for storage; when the system releases heat, the high-temperature working medium stored in the hot water tank 13 exchanges heat with the compressed air flowing through the heat exchange unit 12, and then flows back to the cold water tank 11. During the heat storage process of the system, as the water level in the hot water tank 13 rises, the pressure of the hot water tank 13 will fluctuate; and during the heat release process of the system, as the water level in the hot water tank 13 drops, the pressure of the hot water tank 13 will also fluctuate. Therefore, a constant pressure module 2 is provided, and the pressure value in the hot water tank 13 is obtained in real time by the first pressure measuring instrument 21. When the measured value of the first pressure measuring instrument 21 is lower than the standard pressure lower limit of the hot water tank 13, the nitrogen compressor 23 is controlled to pressurize the nitrogen in the cold water tank 11 and transport it to the hot water tank 13, so that the nitrogen pressure in the hot water tank 13 is increased to a stable pressure. When the measured value of the first pressure measuring instrument 21 is higher than the standard pressure upper limit of the hot water tank 13, the pressure reducing valve group 25 is controlled to decompress the nitrogen in the hot water tank 13 and transport it to the cold water tank 11, so that the nitrogen pressure in the hot water tank 13 is reduced to a stable pressure. Thus, by controlling the amount of nitrogen in the hot water tank 13, the pressure in the hot water tank 13 is maintained stable, thereby reducing the pressure fluctuations generated during the heat storage or heat release process of the system. Since the pressure in the hot water tank 13 remains stable, the pressure fluctuations of the system at this time are only affected by the volume change of the pressurized water working medium in the cold water tank 11. A pressure relief module is further provided. When the second pressure measuring instrument 26 measures an overpressure in the cold water tank 11, the low-temperature working fluid in the cold water tank 11 only needs to be discharged back to the normal pressure water tank 32 through the water discharge circuit 33, so as to maintain the pressure stability of the system, greatly reduce the pressure fluctuation of the system, thereby improving the reliability of the system, eliminating the need to increase the design pressure of the storage tank, and effectively reducing the cost of the pressurized water storage tank.

[0022] Furthermore, a first solenoid valve 221 is provided on the pressurizing pipeline 22 between the cold water tank 11 and the nitrogen compressor 23, a second solenoid valve 222 is provided on the pressurizing pipeline 22 between the hot water tank 13 and the nitrogen compressor 23, the pressure reducing valve group 25 includes a plurality of independently controlled pressure reducing valves, and the opening of the pressure reducing valve group 25 is associated with the measurement values ​​of the first pressure measuring instrument 21 and the second pressure measuring instrument 26.

[0023] Through the implementation of the above-mentioned pressurized water energy storage system embodiment, when the measured value of the first pressure measuring instrument 21 is lower than the standard pressure lower limit of the hot water tank 13, the pressure reducing valve group 25 is closed, the first solenoid valve 221 and the second solenoid valve 222 are opened, and the nitrogen compressor 23 is controlled to pressurize and transport the nitrogen in the cold water tank 11 to the hot water tank 13, so that the nitrogen pressure in the hot water tank 13 is increased to a stable pressure. When the measured value of the first pressure measuring instrument 21 is higher than the standard pressure upper limit of the hot water tank 13, the first solenoid valve 221 and the second solenoid valve 222 are closed, and the pressure reducing valve group 25 is opened, and the pressure reducing valve group 25 is controlled to decompress and transport the nitrogen in the hot water tank 13 to the cold water tank 11, so that the nitrogen pressure in the hot water tank 13 is reduced to a stable pressure. Thus, by using the settings of the first solenoid valve 221, the second solenoid valve 222 and the pressure reducing valve group 25, the pressurization pipeline 22 and the pressure reducing pipeline 24 can be quickly switched to conduction, so that the system can quickly respond to the pressure changes in the hot water tank 13, so as to adjust the nitrogen pressure in the hot water tank 13 in time. In addition, the use of multiple independently controlled pressure reducing valves allows the system to perform precise pressure regulation at different pressure points to meet the pressure regulation requirements under different working conditions. The opening of the pressure reducing valve group 25 is adjusted according to the measured values ​​of the first pressure measuring instrument 21 and the second pressure measuring instrument 26, so as to quickly adjust the pressure in the hot water tank 13 to stabilize. For example: when the pressure in the hot water tank 13 is relatively high and the pressure in the cold water tank 11 is relatively low, the opening of the pressure reducing valve group 25 is increased. When the pressures in the cold water tank 11 and the hot water tank 13 gradually tend to be balanced, the opening of the pressure reducing valve group 25 is reduced.

[0024] Furthermore, a nitrogen filling point 223 is arranged on the pressurized pipeline 22 between the first solenoid valve 221 and the cold water tank 11, and the nitrogen filling point 223 is connected to a nitrogen source, so that after the nitrogen is filled from the nitrogen filling point 223, the filled nitrogen enters the hot water tank 13 and the cold water tank 11 in sequence through the nitrogen compressor 23, and a third solenoid valve 224 is arranged on the pressurized pipeline 22 between the nitrogen filling point 223 and the cold water tank 11.

[0025] Through the implementation of the above-mentioned pressurized water energy storage system embodiment, the system is first filled with nitrogen, and after the nitrogen filling is completed, the low-temperature pressurized water working medium is injected into the cold water tank 11 to realize the subsequent system heat storage or heat release. When the nitrogen is initially filled, the third solenoid valve 224 and the pressure reducing valve group 25 are closed, and the first solenoid valve 221 and the second solenoid valve 222 are opened, so that when the nitrogen is filled, the filled nitrogen is pressurized and injected into the hot water tank 13 through the nitrogen compressor 23, and then flows out from the hot water tank 13 and is injected into the cold water tank 11 through the heat exchange unit 12. When the system is in the process of heat storage or heat release operation, quantitative air replenishment is required to maintain the pressure balance in the cold water tank 11 and the hot water tank 13. At this time, the pressure reducing valve group 25 is closed, and the filled nitrogen is pressurized and injected into the hot water tank 13 through the nitrogen compressor 23. Then close the nitrogen compressor 23, and open the pressure reducing valve group 25 and the third solenoid valve 224, so that the nitrogen in the hot water tank 13 enters the cold water tank 11 through the pressure reducing valve group 25. Therefore, the pressure reducing valve group 25 and the nitrogen compressor 23 are controlled in association, that is, the nitrogen compressor 23 can be started only when the pressure reducing valve group 25 is closed. This helps to continuously establish a balance between the internal pressure of the hot water tank 13 and the internal pressure of the cold water tank 11, so as to reduce the impact of sudden pressure changes on the system.

[0026] Furthermore, a high-temperature working medium outlet pipeline 131 is connected between the hot water tank 13 and the heat exchange unit 12, and a regulating valve group 132 is provided on the high-temperature working medium outlet pipeline 131. The regulating valve group 132 includes a plurality of independently controlled regulating valves, so that the high-temperature working medium flows out from the hot water tank 13 through the high-temperature working medium outlet pipeline 131. A high-temperature working medium inlet pipeline 133 is also connected between the hot water tank 13 and the heat exchange unit 12, and a first working medium pressure pump 134 is provided on the high-temperature working medium inlet pipeline 133, which is used to extract the high-temperature working medium after heat exchange and introduce it into the hot water tank 13 through the high-temperature working medium inlet pipeline 133. A fourth solenoid valve 135 is provided on the high-temperature working medium inlet pipeline 133 between the first working medium pressure pump 134 and the hot water tank 13, and a fifth solenoid valve 136 is provided on the high-temperature working medium inlet pipeline 133 between the first working medium pressure pump 134 and the heat exchange unit 12.

[0027] Through the implementation of the above-mentioned pressurized water energy storage system embodiment, the high-temperature working medium outlet pipeline 131 and the high-temperature working medium inlet pipeline 133 are set in parallel. When the system is storing heat, the fourth solenoid valve 135 and the fifth solenoid valve 136 are opened, the regulating valve group 132 is closed, and the low-temperature pressurized water working medium flows out of the cold water tank 11, is heated by the compressed air passing through the heat exchange unit 12, and enters the hot water tank 13 after being pressurized by the first working medium booster pump 134. When the system releases heat, the fourth solenoid valve 135 and the fifth solenoid valve 136 are closed, the regulating valve group 132 is opened, and the high-temperature pressurized water working medium flows out of the hot water tank 13, and can enter the heat exchange unit 12 through the regulating valve group 132 under the pressure difference between the hot water tank 13 and the cold water tank 11, and enter the cold water tank 11 after being cooled by the air passing through the heat exchange unit 12. That is, the working fluid in the hot water tank 13 expands in volume and increases in pressure due to its high temperature, and a pressure difference is formed between it and the cold water tank 11, which can naturally drive the high-temperature working fluid from the hot water tank 13 to the cold water tank 11. Therefore, during the heat release process of the system, no additional pumping force is required, which greatly reduces the power consumption of the first working fluid booster pump 134, and helps to improve the overall energy efficiency of the system to save costs. Among them, during the initial nitrogen filling, the filling nitrogen entering the hot water tank 13 also flows into the cold water tank 11 through the high-temperature working fluid outlet pipeline 131. In addition, by using multiple independently controlled regulating valves, the flow rate of the high-temperature pressurized water working fluid flowing out of the hot water tank 13 can be accurately adjusted when the system releases heat to meet different adjustment requirements during heat exchange.

[0028] Further, the heat exchange unit 12 includes a common heat exchanger 121, and a medium flow channel and an air flow channel arranged in the common heat exchanger 121. A working fluid delivery pipeline 111 is arranged on the cold water tank 11, and the cold water tank 11 is connected to one end of the medium flow channel through the working fluid delivery pipeline 111. A sixth solenoid valve 112 is arranged on the working fluid delivery pipeline 111, and a high-temperature working fluid outlet pipeline 131 and a high-temperature working fluid inlet pipeline 133 are respectively connected to the other end of the medium flow channel. A first air delivery pipeline 122 and a second air delivery pipeline 123 are arranged on the common heat exchanger 121, and the first air delivery pipeline 122 is connected to one end of the air flow channel, and the second air delivery pipeline 123 is connected to the other end of the air flow channel.

[0029] Through the implementation of the above-mentioned pressurized water energy storage system embodiment, the shared heat exchange form can be applied to the multi-stage compression energy storage system, that is, the first air delivery pipeline 122 on the shared heat exchanger 121 is connected to the upper compressor and the lower expander, and the second air delivery pipeline 123 on the shared heat exchanger 121 is connected to the lower compressor and the upper expander. When the high-temperature compressed air at the outlet of the upper compressor passes through the air flow channel in the shared heat exchanger 121, it heats the low-temperature pressurized water working medium passing through the medium flow channel, and then enters the lower compressor to complete the system energy storage. Or when the low-temperature released air at the outlet of the upper expander passes through the air flow channel in the shared heat exchanger 121, it absorbs heat from the high-temperature pressurized water working medium passing through the medium flow channel, and then enters the lower expander to complete the system energy release. In this way, shared heat exchange for energy storage and energy release is realized, and then the effective transfer and utilization of thermal energy is realized, the energy conversion efficiency is improved, and the area of ​​the heat exchanger required to be configured in the conventional energy storage system can be greatly reduced.

[0030] Furthermore, a first temperature measuring instrument 124 and a flow measuring instrument 125 are provided on the first air delivery pipeline 122, and a second temperature measuring instrument 126 is provided on the second air delivery pipeline 123. The rotation speed of the first working fluid boosting pump 134 and the opening of the regulating valve group 132 are both associated with the measurement values ​​of the first temperature measuring instrument 124, the flow measuring instrument 125 and the second temperature measuring instrument 126.

[0031] By implementing the above-mentioned pressurized water energy storage system embodiment, at the same time, during the heat exchange process, the first temperature measuring instrument 124 and the flow measuring instrument 125 are used to monitor the air temperature and air flow through the first air delivery pipeline 122 in real time, and the second temperature measuring instrument 126 is used to monitor the air temperature through the second air delivery pipeline 123 in real time. By associating the rotation speed of the first working medium booster pump 134 and the opening of the regulating valve group 132 with the measured values ​​of the first temperature measuring instrument 124, the flow measuring instrument 125 and the second temperature measuring instrument 126, the pressure fluctuation during the working medium heat exchange between the hot water tank 13 and the cold water tank 11 can be reduced. For example: when the system is storing energy, if the inlet air temperature displayed by the first temperature measuring instrument 124 is high, it indicates that the heat content of the air passing through is large, and the speed of the first working fluid booster pump 134 needs to be increased to increase the flow rate of the low-temperature water working fluid and improve the heat exchange efficiency; if the air flow rate displayed by the flow measuring instrument 125 is high, it indicates that the flow rate of the air passing through is sufficient, and the speed of the first working fluid booster pump 134 needs to be increased to increase the flow rate of the low-temperature water working fluid and improve the heat exchange efficiency; if the outlet air temperature displayed by the second temperature measuring instrument 126 is low, it indicates that the heat exchange effect is good, and the air has effectively transferred the heat to the low-temperature water working fluid. At this time, the speed of the first working fluid booster pump 134 can be reduced to avoid overheating the working fluid or increasing unnecessary energy consumption. The principle of the opening adjustment of the regulating valve group 132 is the same. The system can automatically adjust the speed of the first working fluid booster pump 134 according to the actual heat exchange temperature and flow conditions of the air, thereby realizing adaptive adjustment to meet the heat exchange requirements while reducing unnecessary energy consumption and avoiding system instability caused by temperature fluctuations or flow changes.

[0032] Furthermore, the water replenishment unit also includes a second working fluid pressure pump 34 arranged on the water replenishment pipeline 31, a seventh solenoid valve 35 is arranged on the water replenishment pipeline 31 between the second working fluid pressure pump 34 and the normal pressure water tank 32, an eighth solenoid valve 36 is arranged on the water replenishment pipeline 31 between the second working fluid pressure pump 34 and the cold water tank 11, and a ninth solenoid valve 37 is arranged on the drain circuit 33.

[0033] Through the implementation of the above-mentioned pressurized water energy storage system embodiment, when the nitrogen filling is completed, the ninth solenoid valve 37 is closed, the seventh solenoid valve 35 and the eighth solenoid valve 36 are opened, and the low-temperature pressurized water working medium in the atmospheric pressure water tank 32 is injected into the cold water tank 11 through the second working medium pressure pump 34 until the preset injection amount is met, and then the seventh solenoid valve 35 and the eighth solenoid valve 36 are closed, and the sixth solenoid valve 112 is opened to facilitate energy storage and heat exchange. When the pressure in the cold water tank 11 is measured to exceed the preset first-level pressure value, the ninth solenoid valve 37 is opened to allow the low-temperature pressurized water working medium in the cold water tank 11 to be discharged back to the atmospheric pressure water tank 32 to achieve pressure relief when the system is over-pressured, thereby ensuring the pressure stability of the system.

[0034] Furthermore, a first liquid level measuring instrument 113 is provided on the cold water tank 11, and a second liquid level measuring instrument 137 is provided on the hot water tank 13. The water injection amount of the cold water tank 11 is associated with the measurement values ​​of the first liquid level measuring instrument 113 and the second liquid level measuring instrument 137, and the rotation speed of the second working fluid booster pump 34 is associated with the measurement value of the first pressure measuring instrument 21.

[0035] Through the implementation of the above-mentioned pressurized water energy storage system embodiment, during the initial water replenishment, the liquid level information of the cold water tank 11 is monitored in real time according to the first liquid level measuring instrument 113, and the water replenishment into the cold water tank 11 is stopped until the liquid level of the cold water tank 11 reaches the preset liquid level. During the energy storage and heat exchange process, considering that a small part of the pressurized water working medium will still be vaporized after the heat exchange, the liquid level information of the hot water tank 13 is monitored in real time according to the second liquid level measuring instrument 137, and the normal pressure water tank 32 is controlled to replenish the cold water tank 11 in time to ensure that the high-temperature pressurized water working medium stored in the hot water tank 13 after the heat exchange reaches the preset liquid level. In addition, the second working medium booster pump 34 is responsible for injecting the normal pressure water working medium in the normal pressure water tank 32 into the cold water tank 11 to maintain or adjust the pressure in the cold water tank 11. Therefore, when the first pressure measuring instrument 21 detects that the pressure in the cold water tank 11 is far below the set value, the rotation speed can be increased to increase the injection speed and pressure of the atmospheric pressure water working medium; and when the pressure in the cold water tank 11 approaches the set value, the rotation speed can be reduced.

[0036] Furthermore, the water replenishment pressure relief module 3 also includes a secondary pressure relief unit, which includes a first air release valve 114 arranged on the cold water tank 11 and a second air release valve 138 arranged on the hot water tank 13 .

[0037] By implementing the above-mentioned pressurized water energy storage system embodiment, by using the setting of the secondary pressure relief unit, when the pressure in the cold water tank 11 or the hot water tank 13 is measured to exceed the preset secondary pressure value, the secondary pressure value is greater than the primary pressure value. By setting the first air release valve 114 and the second air release valve 138, the cold water tank 11 and the hot water tank 13 can automatically release nitrogen to the outside of the environment when the pressure is too high, so as to provide additional constant pressure protection, thereby ensuring that the pressure of the system is always kept stable.

[0038] The present invention also provides a pressure setting method, using the above-mentioned pressurized water energy storage system, the pressure setting method comprises: The nitrogen source is controlled by an external compression device to pressurize and deliver nitrogen to the hot water tank 13 and the cold water tank 11 in turn. After the nitrogen filling is completed, the atmospheric pressure water tank 32 is controlled to replenish the cold water tank 11 with the initial working fluid; During the heat storage or heat release process of the system, the first pressure measuring instrument 21 is controlled to obtain the pressure value in the hot water tank 13 in real time, and the obtained pressure value of the hot water tank 13 is compared with the standard pressure threshold of the hot water tank 13. According to the comparison result, the nitrogen compressor 23 is controlled to pressurize the nitrogen in the cold water tank 11 and transport it to the hot water tank 13, or the pressure reducing valve group 25 is controlled to decompress the nitrogen in the hot water tank 13 and transport it to the cold water tank 11, until the pressure in the hot water tank 13 remains constant; The second pressure measuring instrument 26 is controlled to obtain the pressure value in the cold water tank 11 in real time. If the obtained pressure value of the cold water tank 11 exceeds the preset first-level pressure value, the low-temperature working fluid in the cold water tank 11 is controlled to be discharged into the atmospheric pressure water tank 32. If the obtained pressure value of the cold water tank 11 exceeds the preset second-level pressure value, the nitrogen in the cold water tank 11 and the hot water tank 13 is controlled to be discharged to the outside of the environment.

[0039] By implementing the above-mentioned constant pressure method embodiment and using the above-mentioned pressurized water energy storage system, the working process of the present invention is as follows: S1. Initial working fluid replenishment: The third solenoid valve 224, the pressure reducing valve group 25, the fourth solenoid valve 135, the fifth solenoid valve 136, the seventh solenoid valve 35, the eighth solenoid valve 36, and the ninth solenoid valve 37 are closed, and the first solenoid valve 221, the second solenoid valve 222, the regulating valve group 132, and the sixth solenoid valve 112 are opened. Nitrogen enters the system from the nitrogen filling point 223, and is pressurized by the external compressor and transported to the hot water tank 13 and the cold water tank 11 in sequence. After the nitrogen filling is completed, the third solenoid valve 224, the seventh solenoid valve 35, and the eighth solenoid valve 36 are opened, and the second working medium pressure pump 34 pressurizes the low-temperature pressurized water working medium in the atmospheric water tank 32 and transports it to the cold water tank 11. After the water replenishment is completed, the initial working medium replenishment process of the system ends.

[0040] S2, system heat storage: The seventh solenoid valve 35, the eighth solenoid valve 36, and the pressure reducing valve group 25 are closed, and the fourth solenoid valve 135 and the fifth solenoid valve 136 are opened. The low-temperature pressurized water medium flows out of the cold water tank 11, is heated by the compressed air passing through the common heat exchanger 121, and enters the hot water tank 13 after being pressurized by the first working medium pressure pump 134. As the water level in the hot water tank 13 rises, the pressure of the hot water tank 13 fluctuates. When the measured value of the first pressure measuring instrument 21 is lower than the standard pressure lower limit of the hot water tank 13, the nitrogen compressor 23 is controlled to pressurize the nitrogen in the cold water tank 11 and transport it to the hot water tank 13, so that the nitrogen pressure in the hot water tank 13 is increased to a stable pressure. Or, when the measured value of the first pressure measuring instrument 21 is higher than the standard pressure upper limit of the hot water tank 13, the pressure reducing valve group 25 is controlled to decompress the nitrogen in the hot water tank 13 and transport it to the cold water tank 11, so that the nitrogen pressure in the hot water tank 13 is reduced to a stable pressure.

[0041] S3, system heat release: The fourth solenoid valve 135 and the fifth solenoid valve 136 are closed, and the pressure reducing valve group 25 is opened. The high-temperature pressurized water medium flows out of the hot water tank 13, and enters the common heat exchanger 121 after the flow rate is adjusted by the regulating valve group 132 under the pressure difference between the hot water tank 13 and the cold water tank 11. After being cooled by the compressed air passing through the common heat exchanger 121, it enters the cold water tank 11. As the water level in the hot water tank 13 drops, the pressure of the hot water tank 13 fluctuates. When the measured value of the first pressure measuring instrument 21 is lower than the standard pressure lower limit of the hot water tank 13, the nitrogen compressor 23 is controlled to pressurize the nitrogen in the cold water tank 11 and transport it to the hot water tank 13, so that the nitrogen pressure in the hot water tank 13 is increased to a stable pressure. Or, when the measured value of the first pressure measuring instrument 21 is higher than the standard pressure upper limit of the hot water tank 13, the pressure reducing valve group 25 is controlled to decompress the nitrogen in the hot water tank 13 and transport it to the cold water tank 11, so that the nitrogen pressure in the hot water tank 13 is reduced to a stable pressure.

[0042] S4, overpressure relief: When the pressure in the cold water tank 11 exceeds the preset first-level pressure value, the ninth solenoid valve 37 opens, and the low-temperature pressurized water working medium in the cold water tank 11 is discharged into the normal-pressure water tank 32 .

[0043] When the pressure in the cold water tank 11 or the hot water tank 13 exceeds the preset secondary pressure value, the first air release valve 114 or the second air release valve 138 opens to release the nitrogen in the cold water tank 11 or the hot water tank 13 into the atmosphere to protect the safety of the cold water tank 11 and the hot water tank 13 equipment.

[0044] As described above, the constant pressure method of the present invention is suitable for nitrogen constant pressure in a pressurized water heat storage system, which can stably maintain the storage tank pressure in the pressurized water energy storage system, thereby keeping the nitrogen expansion degree unaffected by the system operation, thereby reducing the pressure fluctuation in the cold water tank 11 or the hot water tank 13.

[0045] It should be understood that the above embodiments are only used to illustrate the technical solutions of the present invention rather than to limit it. For those skilled in the art, the technical solutions described in the above embodiments can be modified, or some of the technical features therein can be replaced by equivalents; and all these modifications and replacements should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A nitrogen constant pressure water energy storage system, characterized in that: The pressurized water energy storage system comprises: An energy storage module, comprising a cold water tank, a heat exchange unit and a hot water tank connected in sequence, wherein the hot water tank is connected to a nitrogen source; A constant pressure and constant pressure module, comprising a pressure measuring unit, a pressurization regulating unit and a decompression regulating unit, wherein the pressure measuring unit comprises a first pressure measuring instrument arranged on the hot water tank, the pressurization regulating unit comprises a pressurization pipeline and a nitrogen compressor, the cold water tank, the nitrogen compressor and the hot water tank are sequentially connected through the pressurization pipeline, the decompression regulating unit comprises a decompression pipeline and a decompression valve group, the hot water tank, the decompression valve group and the cold water tank are sequentially connected through the decompression pipeline; The water replenishment pressure relief module includes a water replenishment unit and a first-level pressure relief unit. The water replenishment unit includes a water replenishment pipeline and a normal-pressure water tank. The normal-pressure water tank is connected to the cold water tank through the water replenishment pipeline. The first-level pressure relief unit includes a water relief circuit connecting the cold water tank and the normal-pressure water tank. The pressure measuring unit also includes a second pressure measuring instrument arranged on the cold water tank.

2. The nitrogen constant pressure and constant pressure pressurized water energy storage system according to claim 1 is characterized in that: A first solenoid valve is provided on the pressurizing pipeline between the cold water tank and the nitrogen compressor, a second solenoid valve is provided on the pressurizing pipeline between the hot water tank and the nitrogen compressor, the pressure reducing valve group includes a plurality of independently controlled pressure reducing valves, and the opening of the pressure reducing valve group is associated with the measured values ​​of the first pressure measuring instrument and the second pressure measuring instrument.

3. The nitrogen constant pressure and constant pressure pressurized water energy storage system according to claim 2 is characterized in that: A nitrogen filling point is arranged on the pressurized pipeline between the first solenoid valve and the cold water tank, and the nitrogen filling point is connected to a nitrogen source, so that after the nitrogen is filled from the nitrogen filling point, the filled nitrogen enters the hot water tank and the cold water tank in sequence through the nitrogen compressor, and a third solenoid valve is arranged on the pressurized pipeline between the nitrogen filling point and the cold water tank.

4. The nitrogen constant pressure and constant pressure pressurized water energy storage system according to claim 1 is characterized in that: A high-temperature working medium outlet pipeline is connected between the hot water tank and the heat exchange unit, and a regulating valve group is arranged on the high-temperature working medium outlet pipeline. The regulating valve group includes a plurality of independently controlled regulating valves, so that the high-temperature working medium flows out from the hot water tank through the high-temperature working medium outlet pipeline. A high-temperature working medium introduction pipeline is also connected between the hot water tank and the heat exchange unit, and a first working medium pressure pump is arranged on the high-temperature working medium introduction pipeline, which is used to extract the high-temperature working medium after heat exchange and introduce it into the hot water tank through the high-temperature working medium introduction pipeline; A fourth solenoid valve is provided on the high-temperature working medium introduction pipeline between the first working medium pressure pump and the hot water tank, and a fifth solenoid valve is provided on the high-temperature working medium introduction pipeline between the first working medium pressure pump and the heat exchange unit.

5. The nitrogen constant pressure and constant pressure pressurized water energy storage system according to claim 4 is characterized in that: The heat exchange unit includes a common heat exchanger, and a medium flow channel and an air flow channel arranged in the common heat exchanger, a working medium delivery pipeline is arranged on the cold water tank, and the cold water tank is connected to one end of the medium flow channel through the working medium delivery pipeline, a sixth solenoid valve is arranged on the working medium delivery pipeline, and the high-temperature working medium outlet pipeline and the high-temperature working medium inlet pipeline are respectively connected to the other end of the medium flow channel; The common heat exchanger is provided with a first air delivery pipe and a second air delivery pipe, wherein the first air delivery pipe is connected to one end of the air flow channel, and the second air delivery pipe is connected to the other end of the air flow channel.

6. The nitrogen constant pressure and constant pressure pressurized water energy storage system according to claim 5 is characterized in that: A first temperature measuring instrument and a flow measuring instrument are provided on the first air delivery pipeline, and a second temperature measuring instrument is provided on the second air delivery pipeline. The rotation speed of the first working fluid booster pump and the opening of the regulating valve group are associated with the measurement values ​​of the first temperature measuring instrument, the flow measuring instrument and the second temperature measuring instrument.

7. The nitrogen constant pressure and constant pressure pressurized water energy storage system according to claim 1 is characterized in that: The water replenishment unit also includes a second working fluid pressure pump arranged on the water replenishment pipeline, a seventh solenoid valve is arranged on the water replenishment pipeline between the second working fluid pressure pump and the normal pressure water tank, an eighth solenoid valve is arranged on the water replenishment pipeline between the second working fluid pressure pump and the cold water tank, and a ninth solenoid valve is arranged on the water discharge circuit.

8. The nitrogen constant pressure and constant pressure pressurized water energy storage system according to claim 7 is characterized in that: The cold water tank is provided with a first liquid level measuring instrument, and the hot water tank is provided with a second liquid level measuring instrument. The water injection amount of the cold water tank is associated with the measurement values ​​of the first liquid level measuring instrument and the second liquid level measuring instrument, and the rotation speed of the second working fluid booster pump is associated with the measurement value of the first pressure measuring instrument.

9. The nitrogen constant pressure and constant pressure pressurized water energy storage system according to claim 1, characterized in that: The water replenishment pressure relief module further includes a secondary pressure relief unit, and the secondary pressure relief unit includes a first air release valve arranged on the cold water tank and a second air release valve arranged on the hot water tank.

10. A constant pressure method, characterized in that: The nitrogen constant pressure pressurized water energy storage system according to any one of claims 1 to 9 is adopted, and the constant pressure method comprises: Control the nitrogen source to pressurize and deliver nitrogen to the hot water tank and the cold water tank in sequence through an external compression device, and after the nitrogen filling is completed, control the atmospheric pressure water tank to initially replenish the working medium to the cold water tank; During the heat storage or heat release process of the system, the first pressure measuring instrument is controlled to obtain the pressure value in the hot water tank in real time, and the obtained pressure value of the hot water tank is compared with the standard pressure threshold of the hot water tank. According to the comparison result, the nitrogen compressor is controlled to pressurize the nitrogen in the cold water tank and transport it to the hot water tank, or the pressure reducing valve group is controlled to decompress the nitrogen in the hot water tank and transport it to the cold water tank, until the pressure in the hot water tank remains constant; The second pressure measuring instrument is controlled to obtain the pressure value in the cold water tank in real time. If the obtained pressure value of the cold water tank exceeds the preset first-level pressure value, the low-temperature working fluid in the cold water tank is controlled to be discharged into the normal pressure water tank. If the obtained pressure value of the cold water tank exceeds the preset second-level pressure value, the nitrogen in the cold water tank and the hot water tank is controlled to be discharged to the outside of the environment.

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