A water vapor energy storage system coupled with a thermal power plant and an operation method thereof

Abstract

The present invention relates to a water vapor energy storage system and operation method for a coupled thermal power plant, comprising an intermediate pressure cylinder inlet connected to the reheated steam generated by the boiler, an intermediate pressure cylinder outlet connected to the low pressure cylinder inlet on one path, a precooler first inlet connected to the low temperature oil tank outlet on the other path, the precooler first outlet connected to the condenser first inlet, the precooler second outlet connected to the high temperature oil tank inlet, the condenser first outlet connected to the medium temperature tank first inlet, the condenser second outlet connected to the medium temperature tank second inlet, the medium temperature tank outlet connected to the flash tank inlet, the flash tank first outlet connected to the low temperature tank inlet, the low temperature tank outlet connected to the condenser second inlet via a pump, the flash tank second outlet connected to the superheater first inlet, the superheater first outlet connected to the turbine inlet, the superheater second inlet connected to the high temperature oil tank outlet, the superheater second outlet connected to the low temperature oil tank inlet, and both the turbine outlet and the low pressure cylinder outlet connected to the condenser inlet. The present invention has two processes: energy storage and energy release.

Description

Technical Field

[0001] The present invention belongs to the technical field of energy storage, and in particular relates to a water vapor energy storage system coupled with a thermal power plant and an operating method thereof. Background Art

[0002] In actual production, coal-fired units participate in deep peak regulation, which requires the unit output to change according to the grid load. However, many units did not consider the need for deep peak regulation at the beginning of their design, and have inherent deficiencies in peak regulation operation.

[0003] To meet peak load regulation requirements, some power plants implement low-pressure cylinder cutouts, eliminating the need for intake air from these cylinders. This reduces the minimum technical output and increases the peak load range. However, the exhaust from the intermediate-pressure cylinders still contains a high level of heat, which can only be used for heating during certain periods of the year, resulting in significant energy waste during the rest of the year. Summary of the Invention

[0004] The present invention aims to provide a water vapor energy storage system and operating method coupled to a thermal power plant to address one or more of the aforementioned technical issues. By coupling the water vapor energy storage system with the power plant, the system stores the exhaust heat from the intermediate pressure cylinders and releases it when peak shaving is no longer required, thereby increasing the output range of the modified units. This system features mature manufacturing technology, strong feasibility, a small footprint, high energy density, and ease of deployment. It can improve the energy utilization and economic benefits of thermal power plants under the context of deep peak shaving.

[0005] In order to achieve the above object, the present invention adopts the following technical solutions:

[0006] A water vapor energy storage system coupled to a thermal power plant, comprising a medium-pressure cylinder, a low-pressure cylinder, a precooler, a condenser, a low-temperature tank, a pump, a medium-temperature tank, a low-temperature oil tank, a high-temperature oil tank, a flash tank, a superheater, a steam turbine, and a condenser;

[0007] The inlet of the intermediate pressure cylinder is connected to the reheated steam generated by the boiler, and the outlet of the intermediate pressure cylinder is divided into two routes, one route is connected to the inlet of the low pressure cylinder, and the other route is connected to the first inlet of the precooler. The second inlet of the precooler is connected to the outlet of the low temperature oil tank. The first outlet of the precooler is connected to the first inlet of the condenser, and the second outlet of the precooler is connected to the inlet of the high temperature oil tank. The first outlet of the condenser is connected to the first inlet of the medium temperature tank, and the second outlet of the condenser is connected to the second inlet of the medium temperature tank. The outlet of the medium temperature tank is connected to the inlet of the flash tank, and the first outlet of the flash tank is connected to the inlet of the low temperature tank. The outlet of the low temperature tank is connected to the second inlet of the condenser through the pump, and the second outlet of the flash tank is connected to the first inlet of the superheater. The first outlet of the superheater is connected to the inlet of the turbine, and the second inlet of the superheater is connected to the outlet of the high temperature oil tank. The second outlet of the superheater is connected to the inlet of the low temperature oil tank. The turbine outlet and the low pressure cylinder outlet are both connected to the inlet of the condenser.

[0008] A further improvement of the present invention is that 160-180°C heat transfer oil is provided in the low-temperature oil tank as a heat storage medium.

[0009] A further improvement of the present invention is that saturated water at 120-145° C. is provided in the low-temperature tank for storing heat.

[0010] A further improvement of the present invention is that the steam at the condenser outlet is sent to a condensate pump.

[0011] A further improvement of the present invention is that the heat storage medium of the medium-temperature tank and the flash tank is water.

[0012] A further improvement of the present invention is that the heat storage medium of the low-temperature oil tank and the high-temperature oil tank are both heat transfer oil.

[0013] A further improvement of the present invention is that a first control valve is provided on the pipe connecting the outlet of the medium-pressure cylinder to the first inlet of the precooler, a second control valve is provided on the pipe connecting the outlet of the medium-pressure cylinder to the inlet of the low-pressure cylinder, a third control valve is provided on the pipe at the outlet of the low-pressure cylinder, a fourth control valve is provided on the pipe connecting the outlet of the low-temperature tank and the pump, a fifth control valve is provided on the pipe connecting the second inlet of the precooler to the outlet of the low-temperature oil tank, a sixth control valve is provided on the pipe connecting the outlet of the medium-temperature tank to the inlet of the flash tank, a seventh control valve is provided on the pipe connecting the second inlet of the superheater to the outlet of the high-temperature oil tank, and an eighth control valve is provided on the pipe connecting the second outlet of the flash tank to the first inlet of the superheater.

[0014] A method for operating a water vapor energy storage system coupled to a thermal power plant, characterized in that the method is based on the water vapor energy storage system coupled to the thermal power plant, and comprises:

[0015] The energy storage process and the energy release process. The energy storage process is the process in which the exhaust from the medium-pressure cylinder of the power plant transfers the heat to the thermal oil and water for storage through the heat exchanger. The energy release process is the process in which the steam generated in the flash tank is heated to a superheated state through the superheater and enters the steam turbine to perform work, so that the thermal energy is converted into electrical energy and released during peak power consumption.

[0016] A further improvement of the present invention is that the energy storage process includes:

[0017] The exhaust gas after the reheated steam enters the intermediate pressure cylinder and performs work enters the precooler to exchange heat with the low-temperature heat transfer oil. The low-temperature heat transfer oil is heated to obtain high-temperature heat transfer oil.

[0018] The low-temperature, low-pressure water in the low-temperature tank is pressurized by the pump to obtain low-temperature, high-pressure water, which then enters the condenser;

[0019] The exhaust gas after heat exchange in the precooler enters the condenser for heat exchange to obtain condensed water, and the low-temperature water is heated to obtain medium-temperature water;

[0020] Condensate and medium-temperature water enter the medium-temperature tank through the first inlet and the second inlet of the medium-temperature tank respectively, and are mixed and stored in the medium-temperature tank;

[0021] Since the exhaust gas from the intermediate pressure cylinder is stored in the water vapor energy storage system, make-up water is introduced into the condenser to ensure the normal operation of the power plant system.

[0022] A further improvement of the present invention is that the energy release process includes:

[0023] The high-pressure medium-temperature water in the medium-temperature tank enters the flash tank for flash evaporation to obtain low-pressure saturated water and low-pressure saturated steam;

[0024] Low-pressure saturated water enters the low-temperature tank for storage, and low-pressure saturated steam enters the superheater to exchange heat with the high-temperature thermal oil to obtain high-temperature, low-pressure superheated steam;

[0025] High-temperature, low-pressure superheated steam enters the steam turbine and expands to produce exhaust gas;

[0026] The exhaust gas is condensed in the condenser to obtain condensate which then enters the condensate pump.

[0027] Compared with the prior art, the present invention has at least the following beneficial technical effects:

[0028] First: through the implementation of the specific steps of the energy storage cycle, the steam entering the low-pressure cylinder to perform work can be introduced into the energy storage system of the present invention, reducing the output of the unit, thereby meeting the needs of deep peak regulation of the power plant, and converting the heat carried in the steam into water and thermal oil for storage, avoiding energy waste.

[0029] Second: Through the implementation of the specific steps of the energy release cycle, the energy stored in the water can be released during peak electricity consumption, steam can be generated using a flash tank, and the steam can be further heated using thermal oil through a superheater. The steam enters the steam turbine to perform work and complete the energy release, thereby improving the economic benefits of the power plant.

[0030] Third, all equipment in this energy storage system utilizes mature technology, offering low investment costs, no manufacturing difficulties, and ease of design and maintenance. The heat storage medium in this energy storage system is liquid, resulting in high energy density, significantly reducing the system's footprint. Furthermore, the main components can be retrofitted from outdated power station facilities. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments or the description of the prior art; obviously, the drawings described below are some embodiments of the present invention, and for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0032] Figure 1 It is a schematic diagram of the overall structure of the present invention.

[0033] Figure 2 Schematic diagram of the energy storage cycle in the present invention.

[0034] Figure 3 Schematic diagram of the energy release cycle in the present invention.

[0035] Description of reference numerals:

[0036] 1. Medium-pressure cylinder, 2. Low-pressure cylinder, 3. Precooler, 4. Condenser, 5. Low-temperature tank, 6. Pump, 7. Medium-temperature tank, 8. Low-temperature oil tank, 9. High-temperature oil tank, 10. Flash tank, 11. Superheater, 12. Steam turbine, 13. Condenser, 14. First control valve, 15. Second control valve, 16. Third control valve, 17. Fourth control valve, 18. Fifth control valve, 19. Sixth control valve, 20. Seventh control valve, 21. Eighth control valve. DETAILED DESCRIPTION

[0037] The technical solutions in the present application will be described clearly and in detail below in conjunction with the accompanying drawings. In the description of the embodiments of the present application, unless otherwise specified, " / " means or, for example, A / B can mean A or B: "and / or" in the text is only a description of the association relationship of associated objects, indicating that there can be three relationships, such as A and / or B, which can mean: A exists alone, A and B exist at the same time, and B exists alone. In addition, in the description of the embodiments of the present application, "multiple" refers to two or more than two. The following terms "first" and "second" are used for descriptive purposes only and cannot be understood as implying or suggesting relative importance or implicitly indicating the number of technical features indicated. Therefore, the features defined as "first" and "second" may explicitly or implicitly include one or more of the features.

[0038] like Figure 1 As shown, the present invention provides a water vapor energy storage system coupled to a thermal power plant, comprising: an intermediate pressure cylinder 1, a low pressure cylinder 2, a precooler 3, a condenser 4, a low temperature tank 5, a pump 6, an intermediate temperature tank 7, a low temperature oil tank 8, a high temperature oil tank 9, a flash tank 10, a superheater 11, a steam turbine 12, a condenser 13, a first control valve 14, a second control valve 15, a third control valve 16, a fourth control valve 17, a fifth control valve 18, a sixth control valve 19, a seventh control valve 20, and an eighth control valve 21.

[0039] The inlet of the medium pressure cylinder 1 is connected to the reheated steam generated by the boiler.

[0040] The inlet of the low-pressure cylinder 2 is connected to the outlet of the medium-pressure cylinder 1.

[0041] The first inlet of the precooler 3 is connected to the outlet of the intermediate pressure cylinder 1.

[0042] The outlet of the low-temperature oil tank 5 is connected to the second inlet of the precooler 3. The low-temperature oil tank 8 is provided with 160-180°C heat transfer oil as a heat storage medium.

[0043] The first inlet of the condenser 4 is connected to the first outlet of the precooler 3 , and the first outlet of the condenser 4 is connected to the first inlet of the medium-temperature tank 7 .

[0044] The outlet of the pump 6 is connected to the second inlet of the condenser 4 .

[0045] The first outlet of the low-temperature tank 5 is connected to the inlet of the pump 6. Saturated water at 120-145°C is provided in the low-temperature tank 5 for storing heat.

[0046] The second outlet of the precooler 3 is connected to the inlet of the high-temperature oil tank 9 , the second outlet of the condenser 4 is connected to the second inlet of the medium-temperature tank 7 , and the outlet of the low-pressure cylinder 2 is connected to the inlet of the condenser 13 .

[0047] The evaporator further includes a flash tank 10, the inlet of which is connected to the outlet of the medium-temperature tank 7, the first outlet of which is connected to the inlet of the low-temperature tank 5, the second outlet of which is connected to the first inlet of the superheater 11, the first outlet of which is connected to the inlet of the steam turbine 12, the second inlet of which is connected to the outlet of the high-temperature oil tank 9, and the second outlet of which is connected to the inlet of the low-temperature oil tank 8. The outlet of the steam turbine 12 is connected to the inlet of the condenser 13.

[0048] The steam at the outlet of condenser 13 goes to the condensate pump.

[0049] The heat storage medium of the medium temperature tank 7 and the flash tank 10 is water.

[0050] The heat storage medium of the low-temperature oil tank 8 and the high-temperature oil tank 9 is heat transfer oil.

[0051] like Figure 1 As shown, the outlet of the low-pressure cylinder 2 and the outlet of the turbine 12 are both connected to the condenser inlet, and the two share the same condenser. Therefore, the condensate generated during the energy release process continues to return to the Rankine cycle of the power plant system to ensure that the total amount of working fluid is not lost.

[0052] like Figure 1As shown, a first control valve 14 is provided on the first inlet of the precooler 3, and a second control valve 15 is provided on the inlet of the low-pressure cylinder 2. The exhaust of the intermediate-pressure cylinder 1 is controlled to enter the energy storage system or the low-pressure cylinder 2 by adjusting the switch of the first control valve 14 and the second control valve 15. A third control valve 16 is provided between the low-pressure cylinder 2 and the condenser 3, a fourth control valve 17 is provided between the low-temperature tank 5 and the pump 6, a fifth control valve 18 is provided between the low-temperature oil tank 8 and the precooler 3, a sixth control valve 19 is provided between the intermediate-temperature tank 7 and the flash tank 10, a seventh control valve 20 is provided between the high-temperature oil tank 9 and the superheater 11, and an eighth control valve 21 is provided between the flash tank 10 and the superheater 11.

[0053] Furthermore, the present invention can adjust the temperatures of the high-temperature oil tank 9 and the low-temperature oil tank 8 according to the actual changes in the exhaust parameters of the medium-pressure cylinder 1 of the power plant, and adjust the pressure of the flash tank 10 as needed, so as to achieve parameter matching for different working conditions and ensure the operating efficiency of the energy storage system.

[0054] Furthermore, the present invention is provided with a first control valve 14, a second control valve 15 and a third control valve 16, which control the flow entering the low-pressure cylinder 2 by adjusting the opening of the valve, thereby realizing low-pressure cylinder cutting, improving the operating flexibility of the original unit, and meeting the needs of deep peak regulation.

[0055] Operation method: In the initial state, all valves from the first control valve 14 to the eighth control valve 21 are closed, and the device is in a shutdown state;

[0056] When the power plant needs deep peak regulation, the second control valve 15, the third control valve 16, the sixth control valve 19, the seventh control valve 20, and the eighth control valve 21 are closed, and the first control valve 14, the fourth control valve 17, and the fifth control valve 18 are opened. The energy storage part of the water vapor energy storage system of the thermal power plant is coupled to work, and the exhaust gas of the intermediate pressure cylinder 1 enters the precooler 3 through the first control valve 14, transfers heat to the low-temperature heat transfer oil in the low-temperature oil tank 8 in the precooler 3, flows out of the precooler 3, flows into the condenser 4, condenses in the condenser 4, exchanges heat with the low-temperature water pressurized by the pump 6 from the low-temperature tank 5, flows out of the condenser 4, and flows into the intermediate temperature tank for storage.

[0057] The low-temperature heat transfer oil in the low-temperature oil tank 8 flows out through the fifth control valve 18, enters the precooler 3, exchanges heat with the exhaust gas of the intermediate pressure cylinder, and flows into the high-temperature oil tank 9 for storage after absorbing heat.

[0058] The low-temperature water in the low-temperature tank 5 flows out through the fourth control valve 17, flows into the pump 6 and is pressurized, enters the condenser, absorbs heat from the working fluid at the outlet of the precooler, and enters the medium-temperature tank 7 for storage after being heated.

[0059] It should be noted that the operation of the energy storage system under peak load regulation will lead to a reduction in the circulating working fluid flow rate within the power plant itself. Therefore, additional make-up water needs to be introduced into the condenser to ensure the normal operation of the power plant.

[0060] When the power plant does not need to peak regulate, the first control valve 14, the second control valve 15, the third control valve 16, the fourth control valve 17, and the fifth control valve 18 are closed, and the sixth control valve 19, the seventh control valve 20, and the eighth control valve 21 are opened, and the energy release part of the water vapor energy storage system of the thermal power plant is coupled to work. The medium-temperature water in the medium-temperature tank 7 flows out through the sixth control valve 19 and flows into the flash tank 10, where the pressure is rapidly reduced. The saturated water generated flows into the low-temperature tank 5, and the saturated steam generated flows out through the eighth control valve 21 and flows into the superheater 11, where it exchanges heat with the high-temperature heat transfer oil in the high-temperature oil tank 9, absorbs heat and becomes superheated steam, and then enters the steam turbine 12 to expand and perform work. The exhaust gas after the work is condensed into condensate through the condenser 13 and then goes to the condensate pump.

[0061] The high-temperature heat transfer oil in the high-temperature oil tank 9 flows out through the seventh control valve 20, transfers heat to saturated steam in the superheater 11, and the low-temperature heat transfer oil after heat exchange flows into the low-temperature oil tank 8 for storage.

[0062] The present invention provides an operating method for a water vapor energy storage system coupled to a thermal power plant, including an energy storage process and an energy release process. The energy storage process is a process in which the exhaust from the intermediate pressure cylinder of the power plant transfers heat to heat transfer oil and water for storage through a heat exchanger. The energy release process is a process in which the steam generated in the flash tank is heated to a superheated state through a superheater and enters a steam turbine to perform work, so that the thermal energy is converted into electrical energy and released during peak power consumption.

[0063] like Figure 2 As shown in Figure 2, the specific steps of the energy storage process are as follows:

[0064] The reheated steam enters the intermediate pressure cylinder and the exhaust gas after work enters the precooler to exchange heat with the low-temperature heat transfer oil. The temperature of the low-temperature heat transfer oil is increased to obtain high-temperature heat transfer oil.

[0065] The low-temperature, low-pressure water in the low-temperature tank is pressurized by a pump to obtain low-temperature, high-pressure water, which then enters the condenser.

[0066] The exhaust gas after heat exchange in the precooler enters the condenser for heat exchange to obtain condensed water. The low-temperature water is heated to obtain medium-temperature water.

[0067] The condensed water and the medium-temperature water enter the medium-temperature tank through the first inlet and the second inlet of the medium-temperature tank respectively, and are mixed and stored in the medium-temperature tank.

[0068] Since the exhaust gas from the intermediate pressure cylinder is stored in the water vapor energy storage system, make-up water is introduced into the condenser to ensure the normal operation of the power plant system.

[0069] like Figure 3 As shown in Figure 2, the specific steps of the energy release process are as follows:

[0070] The high-pressure medium-temperature water in the medium-temperature tank enters the flash tank for flash evaporation to obtain low-pressure saturated water and low-pressure saturated steam.

[0071] Low-pressure saturated water enters the low-temperature tank for storage, and low-pressure saturated steam enters the superheater to exchange heat with the high-temperature heat transfer oil to obtain high-temperature, low-pressure superheated steam.

[0072] High-temperature, low-pressure superheated steam enters the steam turbine, expands and performs work, and obtains exhaust gas.

[0073] The exhaust gas is condensed in the condenser to obtain condensate which then enters the condensate pump.

[0074] In summary, the present invention provides a water vapor energy storage system and operating method coupled to a thermal power plant. This system can store and release energy based on the grid load and the actual peak-shaving requirements of the power plant, thereby improving the power plant's energy utilization and economic benefits. Specific advantages include: First, through the implementation of the specific steps of the energy storage cycle, steam entering the low-pressure cylinder to perform work can be introduced into the energy storage system of the present invention, reducing the unit output, thereby meeting the power plant's deep peak-shaving needs. Heat carried in the steam is converted to water and thermal oil for storage, avoiding energy waste. Second, through the implementation of the specific steps of the energy release cycle, energy stored in the water can be released during peak power demand, generating steam using a flash tank. The steam is further heated using thermal oil in a superheater and then entering the turbine to perform work, completing the energy release and improving the power plant's economic benefits. Third, all equipment in the energy storage system of the present invention utilizes mature technology, resulting in low investment costs, no manufacturing difficulties, and easy design, operation, and maintenance. Fourth, the heat storage medium in this energy storage system is all liquid, with a high energy density, significantly reducing the device's footprint, and the main equipment can be upgraded and repurposed from outdated power plant facilities. Fifth, the present invention can adjust the temperature of the high-temperature oil tank and the low-temperature oil tank according to the actual changes in the exhaust parameters of the medium-pressure cylinder of the power plant, and adjust the pressure of the flash tank as needed to achieve parameter matching for different working conditions and ensure the operating efficiency of the energy storage system. Sixth, the present invention is provided with a first control valve, a second control valve, and a third control valve. By adjusting the opening of the valve, the flow entering the low-pressure cylinder is controlled, and the low-pressure cylinder is cut off, thereby improving the operating flexibility of the original unit and meeting the needs of deep peak regulation. Seventh, the present invention is provided with multiple control valves, and the valve opening can be adjusted to achieve flexible operation of the system.

[0075] It will be understood that the present invention is described by way of some embodiments, and it will be appreciated by those skilled in the art that various changes or equivalent substitutions may be made to these features and embodiments without departing from the spirit and scope of the present invention. In addition, under the teachings of the present invention, these features and embodiments may be modified to adapt to specific circumstances and materials without departing from the spirit and scope of the present invention. Therefore, the present invention is not limited to the specific embodiments disclosed herein, and all embodiments falling within the scope of the claims of this application are intended to be protected by the present invention.

Claims

1. A water vapor energy storage system coupled with a thermal power plant, characterized in that: Including medium-pressure cylinder, low-pressure cylinder, precooler, condenser, low-temperature tank, pump, medium-temperature tank, low-temperature oil tank, high-temperature oil tank, flash tank, superheater, steam turbine and condenser; The inlet of the intermediate pressure cylinder is connected to the reheated steam generated by the boiler, and the outlet of the intermediate pressure cylinder is divided into two routes, one route is connected to the inlet of the low pressure cylinder, and the other route is connected to the first inlet of the precooler. The second inlet of the precooler is connected to the outlet of the low temperature oil tank. The first outlet of the precooler is connected to the first inlet of the condenser, and the second outlet of the precooler is connected to the inlet of the high temperature oil tank. The first outlet of the condenser is connected to the first inlet of the medium temperature tank, and the second outlet of the condenser is connected to the second inlet of the medium temperature tank. The outlet of the medium temperature tank is connected to the inlet of the flash tank, and the first outlet of the flash tank is connected to the inlet of the low temperature tank. The outlet of the low temperature tank is connected to the second inlet of the condenser through the pump, and the second outlet of the flash tank is connected to the first inlet of the superheater. The first outlet of the superheater is connected to the inlet of the turbine, and the second inlet of the superheater is connected to the outlet of the high temperature oil tank. The second outlet of the superheater is connected to the inlet of the low temperature oil tank. The turbine outlet and the low pressure cylinder outlet are both connected to the inlet of the condenser.

2. A water vapor energy storage system coupled to a thermal power plant according to claim 1, characterized in that: The low-temperature oil tank is filled with 160-180℃ heat transfer oil as heat storage medium.

3. The water vapor energy storage system coupled with a thermal power plant according to claim 1, characterized in that: The low temperature tank is filled with saturated water at 120-145℃ for heat storage.

4. The water vapor energy storage system coupled with a thermal power plant according to claim 1, characterized in that: The steam at the condenser outlet goes to the condensate pump.

5. The water vapor energy storage system coupled with a thermal power plant according to claim 1, characterized in that: The heat storage medium of the medium temperature tank and the flash tank is water.

6. The water vapor energy storage system coupled with a thermal power plant according to claim 1, characterized in that: The heat storage medium of low-temperature oil tanks and high-temperature oil tanks is thermal oil.

7. The water vapor energy storage system coupled with a thermal power plant according to claim 1, characterized in that: A first control valve is provided on the pipe connecting the outlet of the medium-pressure cylinder to the first inlet of the precooler, a second control valve is provided on the pipe connecting the outlet of the medium-pressure cylinder to the inlet of the low-pressure cylinder, a third control valve is provided on the pipe at the outlet of the low-pressure cylinder, a fourth control valve is provided on the pipe connecting the outlet of the low-temperature tank and the pump, a fifth control valve is provided on the pipe connecting the second inlet of the precooler to the outlet of the low-temperature oil tank, a sixth control valve is provided on the pipe connecting the outlet of the medium-temperature tank to the inlet of the flash tank, a seventh control valve is provided on the pipe connecting the second inlet of the superheater to the outlet of the high-temperature oil tank, and an eighth control valve is provided on the pipe connecting the second outlet of the flash tank to the first inlet of the superheater.

8. A method for operating a water vapor energy storage system coupled to a thermal power plant, characterized in that: The method is based on a water vapor energy storage system coupled to a thermal power plant according to any one of claims 1 to 7, comprising: The energy storage process and the energy release process. The energy storage process is the process in which the exhaust from the medium-pressure cylinder of the power plant transfers the heat to the thermal oil and water for storage through the heat exchanger. The energy release process is the process in which the steam generated in the flash tank is heated to a superheated state through the superheater and enters the steam turbine to perform work, so that the thermal energy is converted into electrical energy and released during peak power consumption.

9. The method for operating a water vapor energy storage system coupled to a thermal power plant according to claim 8, characterized in that: Energy storage process, including: The exhaust gas after the reheated steam enters the intermediate pressure cylinder and performs work enters the precooler to exchange heat with the low-temperature heat transfer oil. The low-temperature heat transfer oil is heated to obtain high-temperature heat transfer oil. The low-temperature, low-pressure water in the low-temperature tank is pressurized by the pump to obtain low-temperature, high-pressure water, which then enters the condenser; The exhaust gas after heat exchange in the precooler enters the condenser for heat exchange to obtain condensed water, and the low-temperature water is heated to obtain medium-temperature water; Condensate and medium-temperature water enter the medium-temperature tank through the first inlet and the second inlet of the medium-temperature tank respectively, and are mixed and stored in the medium-temperature tank; Since the exhaust gas from the intermediate pressure cylinder is stored in the water vapor energy storage system, make-up water is introduced into the condenser to ensure the normal operation of the power plant system.

10. The method for operating a water vapor energy storage system coupled to a thermal power plant according to claim 8, characterized in that: The energy release process includes: The high-pressure medium-temperature water in the medium-temperature tank enters the flash tank for flash evaporation to obtain low-pressure saturated water and low-pressure saturated steam; Low-pressure saturated water enters the low-temperature tank for storage, and low-pressure saturated steam enters the superheater to exchange heat with the high-temperature thermal oil to obtain high-temperature, low-pressure superheated steam; High-temperature, low-pressure superheated steam enters the steam turbine and expands to produce exhaust gas; The exhaust gas is condensed in the condenser to obtain condensate which then enters the condensate pump.

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