A high-pressure hot water thermal phase change constant-pressure system and method for compressed air energy storage power stations

Abstract

This invention discloses a high-pressure hot water thermal energy storage phase change constant-pressure system and method for compressed air energy storage power stations, belonging to the field of compressed air energy storage. It includes an atmospheric pressure cold water storage tank, at least one high-pressure hot water storage tank, an energy storage heat exchanger, an energy release heat exchanger, a cold water circulation pump, and a constant-pressure system. A steam space is reserved at the top of the high-pressure hot water storage tank. The constant-pressure system includes a condenser and a high-pressure hot water buffer tank. The constant-pressure system maintains the pressure stability inside the high-pressure hot water storage tank by condensing steam and buffering pressure fluctuations. During energy release, the hot water is driven by the steam pressure inside the high-pressure hot water storage tank, eliminating the need for a hot water circulation pump. This invention, through cold and hot water separation, steam phase change constant-pressure design, and a pump-free design, significantly reduces the number and pressure levels of high-pressure hot water storage tanks, lowers equipment investment, and simultaneously improves thermal storage temperature and system efficiency, providing an efficient and economical solution for the large-scale application of compressed air energy storage power stations.

Description

Technical Field

[0001] This invention relates to the field of compressed air energy storage technology, and in particular to a high-pressure hot water thermal phase change constant pressure system and method for compressed air energy storage power stations. Background Technology

[0002] Compressed air energy storage, as a major component of new energy storage, is an effective means to improve the regulation capacity of power systems and is ready for large-scale commercial application. With technological advancements, compressed air energy storage power plants are facing higher efficiency requirements. The heat exchange temperature is a key factor limiting the efficiency of compressed air energy storage power plants; increasing the heat exchange temperature is beneficial to improving the overall efficiency of the power plant, thereby enhancing its operational economy.

[0003] The heat exchange medium can be heat transfer oil, water, or molten salt + water. As the temperature of the heat exchange medium increases, the overall power plant efficiency generally shows an upward trend, and a higher temperature of the heat exchange medium can lead to a higher overall power plant efficiency.

[0004] Although using heat transfer oil as a heat storage and exchange medium can achieve a high heat storage and exchange temperature at normal pressure, heat transfer oil is expensive and needs to be replenished every year, which increases investment, operation and maintenance costs. The high initial investment and operation and maintenance costs restrict the application of heat transfer oil.

[0005] The compressed air energy storage power station with "medium-temperature water + molten salt" composite heat storage and exchange can also achieve a high heat storage and exchange temperature. At the same time, the initial investment and operating costs are lower than those of heat transfer oil. However, due to the presence of two heat storage and exchange media, the process system is complex, the system resistance loss is large, and the operation and maintenance are difficult.

[0006] Using water as the heat exchange medium results in the lowest initial investment and operation and maintenance costs. However, to achieve higher heat exchange rates, the atmospheric water needs to be pressurized, requiring pressurized tanks with nitrogen stabilization. As the water temperature rises, the pressure on the tanks increases, necessitating a significant increase in wall thickness, which greatly increases manufacturing costs and complexity. Furthermore, with the increasing scale of compressed air energy storage power stations, the total tank volume increases substantially, leading to a greater number of tanks and a larger footprint, significantly increasing land costs. Currently, the heat exchange temperature for water-based systems in China is 190℃, with a tank design pressure of 1.6MPa. A dual-tank system is used, with separate hot and cold water tanks connected at the top by nitrogen. Both hot and cold water tanks are high-pressure spherical tanks. For large-scale units, further increasing the heat exchange temperature would exceed the current pressure vessel design specifications' allowed tank wall thickness, thus limiting further parameter improvements for water-based heat exchange systems. Given the low cost and high safety of water as a medium, how to effectively control the tank volume and reduce the working pressure of the tank while further increasing the heat exchange temperature of the water medium has become a technical challenge. Summary of the Invention

[0007] The technical problem to be solved by this invention is to provide a high-pressure hot water thermal storage phase change constant pressure system and method for compressed air energy storage power stations, in order to solve the technical problems of excessively high tank pressure, soaring investment costs, and complex systems caused by increasing the thermal storage temperature when using water as the medium for thermal storage. By separating hot and cold water storage, using steam phase change constant pressure and designing without hot water pump drive, the system can significantly reduce the number of high-pressure tanks, pressure levels, and equipment investment, while achieving higher thermal storage temperature and system efficiency, providing an efficient and economical solution for the large-scale application of compressed air energy storage power stations.

[0008] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0009] A high-pressure hot water thermal energy storage phase change constant pressure system for a compressed air energy storage power station includes: an atmospheric pressure cold water storage tank, at least one high-pressure hot water storage tank, an energy storage heat exchanger, an energy release heat exchanger, a cold water circulation pump, and a constant pressure system.

[0010] The high-pressure hot water storage tank has a reserved steam space at the top;

[0011] The water-side inlet of the energy storage heat exchanger is connected to the atmospheric pressure cold water storage tank, and its water-side outlet is connected to the hot water inlet of the high-pressure hot water storage tank through a hot water pipeline. Its high-temperature working fluid side is used to introduce high-temperature fluid for the compression energy storage process.

[0012] The water-side inlet of the energy release heat exchanger is connected to the hot water outlet of the high-pressure hot water storage tank through a hot water pipeline, and its water-side outlet is connected to the atmospheric pressure cold water storage tank. Its low-temperature working fluid side is used to introduce the low-temperature high-pressure fluid before expansion and energy release.

[0013] The cold water circulation pump is installed on the pipeline between the atmospheric pressure cold water storage tank and the energy storage heat exchanger.

[0014] The constant pressure system includes a condenser and a high-pressure hot water buffer tank, the inlet of which is connected to the steam space; the condenser is used to condense the steam from the steam space and send the condensate to the high-pressure hot water buffer tank; the hot water outlet of the high-pressure hot water buffer tank is connected to the hot water inlet of the high-pressure hot water storage tank or the hot water circulation pipeline;

[0015] The system maintains pressure stability in the high-pressure hot water storage tank through the phase change of steam condensation in the condenser; during energy release, the hot water in the high-pressure hot water storage tank is driven by the steam pressure inside the tank to flow through the energy release heat exchanger.

[0016] A further improvement of the technical solution of the present invention is that the cold water circulation pump is a first cold water circulation pump, a second cold water circulation pump and a third cold water circulation pump configured in parallel, and the capacity of each pump is 50% of the rated capacity of the system.

[0017] A further improvement of the technical solution of the present invention is that the constant pressure system further includes a constant pressure pump, the inlet of which is connected to the atmospheric pressure cold water storage tank and the outlet is connected to the cold side inlet of the condenser, for supplying cooling water to the condenser.

[0018] A further improvement of the technical solution of the present invention is that it also includes a backup pipeline, which is connected between the outlet main pipe of the cold water circulation pump and the cold side inlet of the condenser.

[0019] A further improvement of the technical solution of the present invention is that the steam space at the top of the high-pressure hot water storage tank is filled with a mixture of nitrogen and steam.

[0020] A further improvement of the technical solution of the present invention is that a check valve is provided on the pipeline between the hot water outlet of the high-pressure hot water storage tank and the hot side inlet of the energy release heat exchanger, and on the pipeline between the condensate outlet of the condenser and the high-pressure hot water buffer tank.

[0021] A further improvement of the technical solution of the present invention is that: no bypass valve is configured in the regulating valves of the cold water circulation pipeline, the energy release heat exchange pipeline and the constant pressure system cooling pipeline of the system.

[0022] A method for energy storage using a high-pressure hot water thermal phase change constant-pressure system in a compressed air energy storage power station includes the following steps:

[0023] Energy storage steps: Start the cold water circulation pump to pressurize the cold water in the atmospheric pressure cold water storage tank and deliver it to the energy storage heat exchanger for heating, generating high temperature and high pressure hot water, which is then injected into the high pressure hot water storage tank for storage;

[0024] Pressure stabilization step: Steam in the steam space at the top of the high-pressure hot water storage tank is introduced into the condenser for condensation, and the condensed hot water is returned to the high-pressure hot water storage tank via the high-pressure hot water buffer tank to maintain its internal pressure stability.

[0025] A further improvement of the technical solution of the present invention is that, in the pressure-regulating step, the pressure inside the high-pressure hot water storage tank is adjusted by controlling the condensation rate of the condenser.

[0026] A method for releasing energy using a high-pressure hot water thermal phase change constant-pressure system in a compressed air energy storage power station includes the following steps:

[0027] Relying on the steam pressure inside the high-pressure hot water storage tank, the high-temperature and high-pressure hot water stored therein is driven to the energy release heat exchanger for heat exchange and cooling.

[0028] The cooled water is then transported back to the atmospheric pressure cold water storage tank for storage.

[0029] During the energy release process, the driving force for hot water to flow from the high-pressure hot water storage tank to the energy release heat exchanger originates entirely from the steam pressure inside the high-pressure hot water storage tank.

[0030] The technological advancements achieved by this invention due to the adoption of the above technical solutions are as follows:

[0031] 1. This invention achieves a significant reduction in the design pressure of high-pressure hot water storage tanks (by 40-50%) by employing separate storage of cold and hot water and a condenser-based steam phase change constant pressure technology. This reduces the number of high-pressure storage tanks required by approximately 50% and allows for safe operation at higher heat storage temperatures, thereby reducing initial investment while improving power plant efficiency. Energy release is driven solely by the steam pressure inside the tank, eliminating the need for a hot water circulation pump and simplifying the system. The high-pressure hot water buffer tank effectively absorbs and buffers pressure fluctuations, enhancing system stability.

[0032] 2. This invention uses three 50% capacity cold water circulating pumps in parallel configuration, providing 50% backup capacity. This ensures that the system can still operate at full load when a single pump fails, or maintain partial capacity operation during maintenance, which greatly improves the operational reliability, flexibility and maintainability of the energy storage process.

[0033] 3. By setting up a dedicated constant pressure pump, this invention provides an independent, controllable and reliable cooling water source for the condenser. This is the key power guarantee for achieving a stable and efficient constant pressure steam phase change process, ensuring rapid response and precise control of system pressure regulation.

[0034] 4. This invention establishes a safety redundancy for the constant pressure cooling system by setting a backup pipeline between the outlet main pipe of the cold water circulation pump and the condenser. When the constant pressure pump fails, the cooling water can be seamlessly switched to the cold water circulation pump, ensuring the continuity of the constant pressure function and significantly improving the availability and operational safety of the entire system.

[0035] 5. By maintaining a mixed gas environment of nitrogen and steam at the top of the high-pressure hot water storage tank, the present invention can achieve sensitive and flexible pressure regulation by utilizing the phase change of steam, and can also use inert nitrogen to prevent internal oxidation and corrosion. At the same time, it serves as a stable working fluid for the closed system, reducing the maintenance requirements during long-term operation.

[0036] 6. This invention installs check valves on key pipelines such as hot water outlet and condensate outlet, which can effectively prevent the backflow of high-temperature hot water or condensate, avoid disrupting the pressure balance and steam space stability in the high-pressure hot water storage tank, and is an important hardware measure to ensure the system operates independently, safely, and in the designed direction.

[0037] 7. The system provided by this invention does not have bypass valves on the main regulating valves, but only manual valves before and after the valves for maintenance. This design greatly simplifies the piping system and valve configuration, reduces the number of equipment, lowers investment and maintenance costs, and clarifies the maintenance isolation point, thus improving operational safety.

[0038] 8. The energy storage method provided by this invention clearly defines the entire process of high-pressure hot water preparation, storage and system pressure stabilization through two coordinated steps: "energy storage" and "pressure stabilization". Because the aforementioned pressure stabilization system is adopted, the main pumps (cold water circulation pump and pressure stabilization pump) can be operated at industrial frequency, which reduces equipment investment and control system complexity, and provides a reliable process for efficient energy storage.

[0039] 9. This invention precisely regulates the tank pressure by actively controlling the condensation rate of the condenser, realizing dynamic and refined closed-loop management of the system's core state parameters, and improving the system's adaptability and operational economy under different loads and operating conditions.

[0040] 10. The energy release method provided by this invention fully utilizes the steam pressure inside the high-pressure hot water storage tank as the sole driving force for energy release, and the process is simple. Its driving force comes entirely from the steam pressure, completely eliminating the need for the hot water circulation pump and its auxiliary systems. This not only simplifies operation and reduces energy consumption, but also fundamentally eliminates equipment failure points and maintenance costs in this process, highlighting the core advantage of system simplification. Attached Figure Description

[0041] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0042] Figure 1 This is a schematic diagram of a high-pressure hot water thermal phase change constant pressure system for a compressed air energy storage power station provided in an embodiment of the present invention;

[0043] Among them, A, atmospheric pressure cold water storage tank; B, constant pressure pump; C, first cold water circulation pump; D, second cold water circulation pump; E, third cold water circulation pump; F, energy storage heat exchanger; G, energy release heat exchanger; H, condenser; I, high-pressure hot water buffer tank; J, high-pressure hot water storage tank; K, hot water header; L, ring header; 1, first electrically operated shut-off valve; 2, second electrically operated shut-off valve; 3, first check valve; 4, third electrically operated shut-off valve; 5, fourth electrically operated shut-off valve; 6, second check valve; 7, fifth electrically operated shut-off valve; 8, sixth electrically operated shut-off valve; 9, third check valve; 10, seventh electrically operated shut-off valve; 11, first manually operated shut-off valve; 12, first regulating valve; 13, second manually operated shut-off valve; 14, first pneumatic valve. 15. Eighth electrically operated shut-off valve; 16. Ninth electrically operated shut-off valve; 17. Tenth electrically operated shut-off valve; 18. Third manually operated shut-off valve; 19. Second pneumatically operated pressure reducing valve; 20. Fourth manually operated shut-off valve; 21. Eleventh electrically operated shut-off valve; 22. Fifth manually operated shut-off valve; 23. Fourth check valve; 24. Twelfth electrically operated shut-off valve; 25. Sixth manually operated shut-off valve; 26. Second regulating valve; 27. Seventh manually operated shut-off valve; 28. Thirteenth electrically operated shut-off valve; 29. ​​Fourteenth electrically operated shut-off valve; 30. Fifth check valve; 31. Sixth check valve; 32. Seventh check valve; 33. Fifteenth electrically operated shut-off valve; 34. Sixteenth electrically operated shut-off valve; 35. Third pneumatically operated pressure reducing valve. Detailed Implementation

[0044] It should be noted that the terms "comprising" and "having" and any variations thereof in the specification, claims and accompanying drawings of this invention are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units explicitly listed, but may include other steps or units not explicitly listed or inherent to such process, method, product or device.

[0045] In the description of this invention, it should be understood that the terms "center," "longitudinal," "lateral," "length," "width," "thickness," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this invention.

[0046] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Thus, a feature defined as "first" or "second" may explicitly or implicitly include at least one of that feature. In the description of this invention, "a plurality of" means at least two, such as two, three, etc., unless otherwise explicitly specified.

[0047] The present invention will be further described in detail below with reference to the accompanying drawings and embodiments:

[0048] like Figure 1 As shown, a high-pressure hot water thermal phase change constant-pressure system for compressed air energy storage power stations includes:

[0049] A atmospheric pressure cold water storage tank A, at least one high pressure hot water storage tank J, energy storage heat exchanger F, energy release heat exchanger G, cold water circulation pump and constant pressure system;

[0050] Atmospheric pressure cold water storage tank A is used to store atmospheric pressure cold water;

[0051] High-pressure hot water storage tank J is used to store high-temperature and high-pressure hot water, and its top is reserved with steam space (the steam spaces are interconnected and together form the system's steam pressure balance network - ring main pipe L); hot water main pipe K, whose main pipeline connects to energy storage heat exchanger F, energy release heat exchanger G and inlet and outlet branch pipelines connecting each high-pressure hot water storage tank J, forms a high-temperature and high-pressure hot water distribution network.

[0052] The water-side inlet of the energy storage heat exchanger F is connected to the atmospheric pressure cold water storage tank A, and its water-side outlet is connected to the hot water header K. Its high-temperature working fluid side is used to introduce the high-temperature fluid generated during the compression energy storage process.

[0053] The water-side inlet of the energy release heat exchanger G is connected to the hot water header K (the hot water outlet of the high-pressure hot water storage tank J), and its water-side outlet is connected to the atmospheric pressure cold water storage tank A. Its low-temperature working fluid side is used to introduce the fluid that needs to be heated before expansion and energy release.

[0054] A cold water circulation pump is installed on the pipeline between atmospheric pressure cold water storage tank A and energy storage heat exchanger F;

[0055] The constant pressure system includes a condenser H and a high-pressure hot water buffer tank I. The inlet of the constant pressure system is connected to the steam space at the top of the high-pressure hot water storage tank J. The condenser H is used to condense the steam from the steam space (annular header L) and transport the condensed hot water to the high-pressure hot water buffer tank I. The hot water outlet of the high-pressure hot water buffer tank I is connected to the hot water inlet or hot water circulation pipeline of the high-pressure hot water storage tank J. The high-pressure hot water buffer tank I is used to absorb and buffer the pressure fluctuations in the high-pressure hot water storage tank J.

[0056] The system maintains the pressure stability in the high-pressure hot water storage tank J through the steam condensation phase change process in the condenser H; and during energy release, the hot water in the high-pressure hot water storage tank J is driven by the steam pressure inside the tank to flow through the energy release heat exchanger G.

[0057] It should be noted that the pressure may be too low during system startup, at the end of energy release, or during accidental heat dissipation. In this case, the system can add an adjustable external (or system-to-system) steam injection line on the steam line leading to condenser H (before the fifteenth electric shut-off valve 33), equipped with a regulating valve or a small electric heating steam generator connected in parallel next to condenser H, to inject steam into the annular header L to increase the pressure when needed.

[0058] Furthermore, the constant pressure system also includes a constant pressure pump B, whose inlet is connected to an atmospheric pressure cold water storage tank A and whose outlet is connected to the cold side inlet of the condenser H, for supplying cooling water to the condenser H.

[0059] Furthermore, it also includes a backup pipeline, which is connected between the outlet header of the chilled water circulation pump and the cold-side inlet of the condenser H.

[0060] Furthermore, the steam space at the top of the high-pressure hot water storage tank J is filled with a mixture of nitrogen and steam.

[0061] Furthermore, check valves are installed on the pipeline between the hot water outlet of the high-pressure hot water storage tank J and the hot side inlet of the energy release heat exchanger G, and on the pipeline between the condensate outlet of the condenser H and the high-pressure hot water buffer tank I.

[0062] Furthermore, no bypass valves are configured in the regulating valves of the system's cold water circulation pipeline, energy release heat exchange pipeline, and constant pressure system cooling pipeline.

[0063] The locations of the valves installed on each pipeline in the system are shown below:

[0064] 1. Energy release circuit

[0065] On the return water pipeline from the hot side outlet of the heat exchanger G to the atmospheric pressure cold water storage tank A, the following are installed sequentially along the water flow direction: a third manual shut-off valve 18, a second pneumatic regulating and pressure reducing valve 19, a fourth manual shut-off valve 20, and a first electric shut-off valve 1.

[0066] 2. Cold water supply and energy storage circuit

[0067] (1) Pump unit: The first cold water circulation pump C, the second cold water circulation pump D and the third cold water circulation pump E are connected in parallel, and the capacity of each pump is 50% of the rated capacity of the system; two are in operation and one is on standby, the pumps are in operation at the power frequency, and there is no need to set up a hot water circulation pump.

[0068] Each pump is equipped with a second electric shut-off valve 2, a fourth electric shut-off valve 5, and a sixth electric shut-off valve 8 on its inlet pipe, for drawing water from the atmospheric pressure cold water storage tank A.

[0069] Each pump's outlet pipe is equipped with a check valve and an electrically operated shut-off valve in sequence to prevent backflow and control start and stop: at the outlet of the first cold water circulation pump C, there is a first check valve 3 and a third electrically operated shut-off valve 4 in sequence; at the outlet of the second cold water circulation pump D, there is a second check valve 6 and a fifth electrically operated shut-off valve 7 in sequence; at the outlet of the third cold water circulation pump E, there is a third check valve 9 and a seventh electrically operated shut-off valve 10 in sequence.

[0070] (2) Main energy storage pipeline: The cold water header after the outlet pipelines of each pump converge is equipped with a first manual shut-off valve 11, a first regulating valve 12 and a second manual shut-off valve 13 in sequence before entering the cold side inlet of the energy storage heat exchanger F.

[0071] (3) Circulation bypass: A first pneumatic regulating and pressure reducing valve 14 and an eighth electric shut-off valve 15 are connected between the outlet main pipe of the cold water circulation pump and the atmospheric pressure cold water storage tank A;

[0072] (4) Hot water output pipeline: A ninth electric shut-off valve 16 is installed on the pipeline from the hot side outlet of the energy storage heat exchanger F to the high-pressure heat storage tank J.

[0073] 3. High-pressure hot water output circuit: A tenth electric shut-off valve 17 is installed on the hot water outlet of the high-pressure hot water storage tank J to the hot side inlet of the energy release heat exchanger G.

[0074] 4. Constant pressure system circuit

[0075] (1) Cooling water supply

[0076] A fifth manual shut-off valve 22 is installed between the inlet of the atmospheric pressure cold water storage tank A and the inlet of the constant pressure pump B;

[0077] On the outlet pipeline of constant pressure pump B, a fourth check valve 23 and a twelfth electric shut-off valve 24 are installed in sequence.

[0078] On the cooling water branch leading to the condenser H from the twelfth electric shut-off valve 24, the sixth manual shut-off valve 25, the second regulating valve 26 and the seventh manual shut-off valve 27 are installed in sequence.

[0079] On the return branch from the twelfth electric shut-off valve 24 to the atmospheric pressure cold water storage tank A, the third pneumatic regulating and pressure reducing valve 35 and the thirteenth electric shut-off valve 28 are installed in sequence.

[0080] (2) Gas condensation and reflux

[0081] A fifteenth electric shut-off valve 33 is installed on the gas input pipeline between the steam space at the top of the high-pressure hot water storage tank J and the condenser H.

[0082] On the nitrogen return line from the gas outlet of condenser H to the steam space, a sixth check valve 31 and a sixteenth electric shut-off valve 34 are installed in sequence.

[0083] (3) Condensate recovery:

[0084] On the pipeline from the condensate outlet of condenser H to the high-pressure hot water buffer tank I, a fourteenth electric shut-off valve 29 and a fifth check valve 30 are installed in sequence.

[0085] A seventh check valve 32 is installed on the pipeline from the hot water outlet of the high-pressure hot water buffer tank I to the high-pressure hot water storage tank J.

[0086] 5. Backup piping

[0087] An eleventh electric shut-off valve 21 is connected between the outlet main pipe of the cold water circulation pump and the cooling water branch leading to the condenser H (before the sixth manual shut-off valve 25) to form a backup cold source pipeline.

[0088] A method for energy storage using a high-pressure hot water thermal phase change constant-pressure system in a compressed air energy storage power station includes the following steps:

[0089] Energy storage steps: Start the cold water circulation pump to pressurize the cold water in the atmospheric pressure cold water storage tank A and send it to the energy storage heat exchanger F for heating, generating high temperature and high pressure hot water, which is then injected into the high pressure hot water storage tank J for storage.

[0090] Pressure stabilization step: Steam in the steam space at the top of the high-pressure hot water storage tank J is introduced into the condenser H for condensation, and the condensed hot water is returned to the high-pressure hot water storage tank J via the high-pressure hot water buffer tank I to maintain its internal pressure stability.

[0091] Furthermore, in the constant pressure step, the pressure inside the high-pressure hot water storage tank J is adjusted by controlling the condensation rate of the condenser H.

[0092] The specific operation process during energy storage is as follows:

[0093] (a) Normal energy storage heating process

[0094] 1. Valve status preset: Close the first electric shut-off valve 1, the tenth electric shut-off valve 17 and the fifth manual shut-off valve 22; open the ninth electric shut-off valve 16 and the eighth electric shut-off valve 15.

[0095] 2. Cold water supply and circulation: Start two cold water circulation pumps (taking the first cold water circulation pump C and the second cold water circulation pump D as the first cold water circulation pump C and the third cold water circulation pump E as the standby as an example). The cold water in the atmospheric pressure cold water tank A enters the first cold water circulation pump C and the second cold water circulation pump D through the second electric shut-off valve 2 and the fourth electric shut-off valve 5 on its outlet pipeline, respectively.

[0096] 3. Cold water pressurization and diversion: After being pressurized by the cold water circulation pump, the water is discharged from the pump outlet and flows through the check valves (first check valve 3, second check valve 6) and electric shut-off valves (third electric shut-off valve 4, fifth electric shut-off valve 7) on their respective pipelines in sequence, and then merges into the cold water outlet main pipe.

[0097] 4. Flow regulation and heating: The combined cold water is divided into two streams:

[0098] (1) Circulation regulation path: A portion of the cold water is reduced in pressure by the first pneumatic regulating and pressure reducing valve 14 and returned to the atmospheric pressure cold water storage tank A by the eighth electric shut-off valve 15, in order to regulate the total flow of the system.

[0099] (2) Main heating circuit: Another part of the cold water flows through the first manual shut-off valve 11, the first regulating valve 12, and the second manual shut-off valve 13 in sequence, and enters the energy storage heat exchanger F.

[0100] 5. Hot water storage: Cold water absorbs the heat of compression in the energy storage heat exchanger F and is heated to become high temperature and high pressure hot water. Then, it is transported to the high pressure hot water storage tank J for storage through the opened ninth electric shut-off valve 16.

[0101] Specifically, after the cold water is heated into hot water in the energy storage heat exchanger F, it first flows into the hot water header K, and then is distributed to each high-pressure hot water storage tank J through the branch pipes on the hot water header K.

[0102] (ii) Steam phase change constant pressure process (when the tank pressure is too high)

[0103] To stabilize the pressure inside the high-pressure hot water storage tank J, the following pressure stabilization operation is performed when the pressure exceeds the set value:

[0104] 1. Valve status switching: Open the thirteenth electric shut-off valve 28, the fourteenth electric shut-off valve 29, the fifteenth electric shut-off valve 33 and the sixteenth electric shut-off valve 34; ensure that the eleventh electric shut-off valve 21 is in the closed state.

[0105] 2. Gas condensation: The gas (mainly a mixture of water vapor and nitrogen) in the steam space at the top of the high-pressure hot water storage tank J enters the condenser H through the annular header L and the fifteenth electric shut-off valve 33. The water vapor in the condenser is condensed into liquid water and enters the high-pressure hot water buffer tank I.

[0106] 3. Nitrogen reflux: Uncondensed nitrogen is returned to the steam space to maintain system pressure via the gas outlet of condenser H, the sixteenth electric shut-off valve 34, and the sixth check valve 31.

[0107] 4. Cooling water supply (via constant pressure pump B)

[0108] When the constant pressure pump B is started, the cold water in the atmospheric pressure cold water storage tank A is drawn by the constant pressure pump B through the fifth manual shut-off valve 22 and back pressure is applied. After flowing through the fourth check valve 23 and the twelfth electric shut-off valve 24, it is divided into two paths:

[0109] (1) Return flow regulation path: A portion of the cooling water is reduced in pressure by the third pneumatic regulating and pressure reducing valve 35 and returned to the atmospheric pressure cold water storage tank A by the thirteenth electric shut-off valve 28, which is used to regulate the outlet pressure and flow rate of the constant pressure pump B.

[0110] (2) Condenser cooling path: Another part of the cooling water flows through the sixth manual shut-off valve 25, the second regulating valve 26, and the seventh manual shut-off valve 27 in sequence, and enters the cold side of the condenser H as a cold source.

[0111] 5. Condensate recovery and system balancing:

[0112] The cooling water heated in condenser H (i.e., the medium that has absorbed the heat of steam condensation) mixes with the high-temperature water generated during condensation and enters the high-pressure hot water buffer tank I through the fourteenth electrically operated shut-off valve 29 and the fifth check valve 30. The hot water in buffer tank I flows into the hot water header K through the seventh check valve 32, and finally replenishes the high-pressure hot water storage tank J, thereby maintaining the dynamic balance of the system's water volume. This process reduces the total gas volume through steam condensation, thereby stabilizing and lowering the pressure inside the tank.

[0113] (III) Standby Procedure for Constant Pressure System (When Constant Pressure Pump B Fails)

[0114] When the constant pressure pump B fails to operate, activate the backup cold source path as follows:

[0115] 1. Valve status switching: Close the twelfth electric shut-off valve 24 and the thirteenth electric shut-off valve 28; open the eleventh electric shut-off valve 21.

[0116] 2. Backup cold source switching: At this time, the pressurized cold water in the outlet header of the cold water circulation pump is used as a backup cold source and is drawn out through the eleventh electric shut-off valve 21 to replace the constant pressure pump B for water supply.

[0117] 3. Complete pressure stabilization: The standby cold water then flows through the sixth manual shut-off valve 25, the second regulating valve 26, and the seventh manual shut-off valve 27 into the condenser H, continuing the steam condensation pressure stabilization process in Part (II) above, ensuring that the system pressure control is not interrupted.

[0118] A method for releasing energy using a high-pressure hot water thermal phase change constant-pressure system in a compressed air energy storage power station includes the following steps:

[0119] Relying on the steam pressure inside the high-pressure hot water storage tank J, the high-temperature and high-pressure hot water stored therein is driven to the energy release heat exchanger G for heat exchange and cooling.

[0120] The cooled water is then transported back to atmospheric pressure cold water storage tank A for storage.

[0121] During the energy release process, the driving force for hot water to flow from the high-pressure hot water storage tank J to the energy release heat exchanger G originates entirely from the steam pressure inside the high-pressure hot water storage tank J.

[0122] The specific operation process during energy release is as follows:

[0123] 1. Valve status preset: Open the first electric shut-off valve 1 and the tenth electric shut-off valve 17; close the ninth electric shut-off valve 16, the eighth electric shut-off valve 15, the thirteenth electric shut-off valve 28, the fifteenth electric shut-off valve 33 and the sixteenth electric shut-off valve 34, thereby isolating the energy storage and constant pressure pipelines and connecting the energy release circuit.

[0124] 2. Hot water release and drive: Driven by the saturated steam pressure inside the high-pressure hot water storage tank J (the vaporization pressure maintained by the high-temperature hot water inside the tank), the high-temperature and high-pressure hot water stored in the tank first flows into the hot water header K, and then flows out through the tenth electric shut-off valve 17, entering the hot side of the energy release heat exchanger G.

[0125] 3. Heat release and cooling: High-temperature and high-pressure hot water exchanges heat with the low-temperature expansion medium (from the expansion and energy release process) flowing through its cold side in the heat exchanger G, releasing its heat energy to the low-temperature medium and being cooled itself.

[0126] 4. Cooling water recovery: The water after heat exchange and cooling (i.e., cooling water) flows sequentially through the third manual shut-off valve 18, the second pneumatic regulating and pressure reducing valve 19, the fourth manual shut-off valve 20 and the first electric shut-off valve 1, and finally returns to the atmospheric pressure cold water storage tank A for storage, completing one energy release cycle.

[0127] Finally, it should be noted that 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 foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A high-pressure hot water thermal energy storage phase change constant-pressure system for compressed air energy storage power stations, characterized in that, include: Atmospheric pressure cold water storage tank, at least one high pressure hot water storage tank, energy storage heat exchanger, energy release heat exchanger, cold water circulation pump and constant pressure system; The high-pressure hot water storage tank has a reserved steam space at the top; The water-side inlet of the energy storage heat exchanger is connected to the atmospheric pressure cold water storage tank, and its water-side outlet is connected to the hot water inlet of the high-pressure hot water storage tank through a hot water pipeline. Its high-temperature working fluid side is used to introduce high-temperature fluid for the compression energy storage process. The water-side inlet of the energy release heat exchanger is connected to the hot water outlet of the high-pressure hot water storage tank through a hot water pipeline, and its water-side outlet is connected to the atmospheric pressure cold water storage tank. Its low-temperature working fluid side is used to introduce the low-temperature high-pressure fluid before expansion and energy release. The cold water circulation pump is installed on the pipeline between the atmospheric pressure cold water storage tank and the energy storage heat exchanger; The constant pressure system includes a condenser and a high-pressure hot water buffer tank, the inlet of which is connected to the steam space; the condenser is used to condense the steam from the steam space and send the condensate to the high-pressure hot water buffer tank; the hot water outlet of the high-pressure hot water buffer tank is connected to the hot water inlet of the high-pressure hot water storage tank or the hot water circulation pipeline; The system maintains pressure stability in the high-pressure hot water storage tank through the phase change of steam condensation in the condenser; during energy release, the hot water in the high-pressure hot water storage tank is driven by the steam pressure inside the tank to flow through the energy release heat exchanger.

2. The high-pressure hot water thermal energy storage phase change constant-pressure system for compressed air energy storage power stations according to claim 1, characterized in that, The cold water circulation pump consists of three cold water circulation pumps configured in parallel: a first cold water circulation pump, a second cold water circulation pump, and a third cold water circulation pump. Each pump has a capacity of 50% of the system's rated capacity.

3. The high-pressure hot water thermal phase change constant-pressure system for compressed air energy storage power station according to claim 1, characterized in that, The constant pressure system also includes a constant pressure pump, the inlet of which is connected to the atmospheric pressure cold water storage tank and the outlet of which is connected to the cold side inlet of the condenser, for supplying cooling water to the condenser.

4. The high-pressure hot water thermal energy storage phase change constant-pressure system for compressed air energy storage power station according to claim 3, characterized in that, It also includes a backup pipeline, which is connected between the outlet header of the cold water circulation pump and the cold side inlet of the condenser.

5. The high-pressure hot water thermal energy storage phase change constant-pressure system for compressed air energy storage power stations according to claim 1, characterized in that, The steam space at the top of the high-pressure hot water storage tank is filled with a mixture of nitrogen and steam.

6. The high-pressure hot water thermal energy storage phase change constant-pressure system for compressed air energy storage power stations according to claim 1, characterized in that, Check valves are installed on the pipeline between the hot water outlet of the high-pressure hot water storage tank and the hot side inlet of the energy release heat exchanger, and on the pipeline between the condensate outlet of the condenser and the high-pressure hot water buffer tank.

7. The high-pressure hot water thermal energy storage phase change constant-pressure system for compressed air energy storage power station according to claim 1, characterized in that, Bypass valves are not installed in the regulating valves of the system's cold water circulation pipeline, energy release heat exchange pipeline, and constant pressure system cooling pipeline.

8. A method for energy storage using a high-pressure hot water thermal phase change constant-pressure system of a compressed air energy storage power station, wherein the system is the high-pressure hot water thermal phase change constant-pressure system of a compressed air energy storage power station as described in any one of claims 1-7, characterized in that... Includes the following steps: Energy storage steps: Start the cold water circulation pump to pressurize the cold water in the atmospheric pressure cold water storage tank and deliver it to the energy storage heat exchanger for heating, generating high temperature and high pressure hot water, which is then injected into the high pressure hot water storage tank for storage; Pressure stabilization step: Steam in the steam space at the top of the high-pressure hot water storage tank is introduced into the condenser for condensation, and the condensed hot water is returned to the high-pressure hot water storage tank via the high-pressure hot water buffer tank to maintain its internal pressure stability.

9. A method for energy storage using a high-pressure hot water thermal phase change constant-pressure system in a compressed air energy storage power station according to claim 8, characterized in that, In the pressure stabilization step, the pressure inside the high-pressure hot water storage tank is adjusted by controlling the condensation rate of the condenser.

10. A method for releasing energy using a high-pressure hot water thermal phase change constant-pressure system of a compressed air energy storage power station, wherein the system is the high-pressure hot water thermal phase change constant-pressure system of a compressed air energy storage power station as described in any one of claims 1-7, characterized in that... Includes the following steps: Relying on the steam pressure inside the high-pressure hot water storage tank, the high-temperature and high-pressure hot water stored therein is driven to the energy release heat exchanger for heat exchange and cooling. The cooled water is then transported back to the atmospheric pressure cold water storage tank for storage. During the energy release process, the driving force for hot water to flow from the high-pressure hot water storage tank to the energy release heat exchanger originates entirely from the steam pressure inside the high-pressure hot water storage tank.

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