Thermal power-molten salt energy storage coupling system and method for realizing energy-saving heat supply and flexible peak regulation in cooperation

Abstract

This invention belongs to the field of molten salt energy storage and steam extraction / supply, and relates to a thermal power-molten salt energy storage coupling system and method that synergistically achieves energy-saving heating and flexible peak shaving, to solve the problems of difficult thermoelectric decoupling, limited peak shaving capacity, and large steam supply heat loss under low load conditions of thermal power units. The invention includes: an energy charging unit, connecting the turbine unit and power generation system, the molten salt energy storage unit, and the steam supply unit, which transfers part of the heat energy of the extracted steam to the molten salt; the released steam then enters the steam supply unit; the molten salt energy storage unit, containing high-temperature and low-temperature molten salt tanks; and an energy release unit, which uses high-temperature molten salt to heat boiler feedwater and deliver it to the boiler. This invention uses molten salt as an energy carrier and employs a synchronous charging and releasing method to utilize the superheat of the extracted steam, replacing water spray desuperheating to reduce heat loss, achieving energy cascade utilization and reducing boiler load. By switching the on / off states of valves, multiple operating modes are achieved, including energy storage, energy release, and cyclic energy-saving heating, realizing thermoelectric decoupling and deep peak shaving of the unit while meeting steam supply requirements.

Description

Technical Field

[0001] This invention belongs to the field of molten salt energy storage steam extraction and supply, and specifically relates to a thermal power-molten salt energy storage coupling system and method that synergistically achieves energy-saving heating and flexible peak shaving. Background Technology

[0002] With the advancement of the national strategies for "carbon peaking" and "carbon neutrality," the proportion of new clean energy power, represented by solar photovoltaic and wind power, integrated into the power grid has increased significantly. New energy power generation inherently possesses intermittent and fluctuating characteristics, and its large-scale grid connection has led to a shift in the role of traditional thermal power generating units in the grid from baseload power sources to regulating power sources. To ensure the safe and stable operation of the power grid and to absorb new energy power, thermal power units need to frequently participate in deep peak shaving, posing a severe challenge to their operational flexibility.

[0003] To achieve flexible retrofitting of thermal power units, existing technologies mainly proceed in two directions: First, internal modifications to the unit itself, such as optimizing the turbine flow path and enhancing boiler combustion stability under low-load conditions, to expand the unit's peak-shaving capacity and shorten start-up and shutdown response time; second, adding energy storage or thermal storage devices externally to the unit, achieving thermoelectric decoupling through energy storage and release, thereby enhancing operational flexibility. Among various energy and thermal storage technologies, molten salt energy storage technology has gained widespread engineering application due to the excellent thermal stability, high specific heat capacity, good chemical stability, and low saturated vapor pressure of the molten salt medium.

[0004] Existing thermal power-molten salt energy storage coupling systems typically use main boiler steam, reheat steam, or high-temperature flue gas to heat the molten salt. However, in actual operation, the above coupling scheme has the following technical limitations:

[0005] First, under low-load conditions, the reduced power generation load leads to a synchronous decrease in steam parameters. Since the saturation temperature corresponding to the steam pressure is lower than the risk temperature of molten salt solidification, only a small amount of steam can be extracted to exchange sensible heat with molten salt, which cannot achieve the energy storage capacity required for deep peak shaving.

[0006] Second, when high-pressure main steam is used as a heat source for deep energy storage, the extraction flow rate of high-pressure main steam is strictly limited due to the safety constraints of the boiler reheater wall temperature, making it difficult to meet the energy storage power requirements of deep peak shaving of the unit.

[0007] Third, under low-load conditions, in order to meet the demand for external heating or industrial steam supply, the unit usually needs to maintain a high output level. There is a strong correlation between thermal load and electrical load, making it difficult to achieve thermal-electric decoupling, which restricts the unit's deep peak-shaving capability.

[0008] Fourth, when existing thermal power units supply steam to the outside world, in order to meet the steam supply parameter requirements, they often use water spray desuperheating to adjust the steam temperature. This process generates a large amount of irreversible heat loss, which reduces the overall thermal economy of the unit.

[0009] Therefore, there is an urgent need to propose a thermal power-molten salt energy storage coupling system and its control method that can achieve deep peak shaving and thermal-electric decoupling of thermal power units while ensuring the external steam supply capacity, and simultaneously reduce heat loss in the steam supply process. Summary of the Invention

[0010] To address the aforementioned problems in the existing technology, namely the difficulty in thermoelectric decoupling, limited peak-shaving capacity, and large heat loss from steam supply in existing thermal power units under low-load conditions, this invention provides a thermal power-molten salt energy storage coupling system and method that synergistically achieves energy-saving heating and flexible peak-shaving.

[0011] The first aspect of this invention proposes a thermal power-molten salt energy storage coupling system that synergistically achieves energy-saving heating and flexible peak shaving, including a steam turbine unit and a power generation system, and further comprising: The charging unit has its working fluid inlet connected to the steam extraction port of the turbine unit and the power generation system, and its working fluid outlet connected to the steam supply unit. The charging unit is used to receive the extracted steam and transfer part of the excess heat energy of the extracted steam to the molten salt medium for storage, and to transfer the extracted steam to the steam supply unit 5. A molten salt energy storage unit includes a high-temperature molten salt tank and a low-temperature molten salt tank. The charging inlet of the molten salt energy storage unit is connected to the medium outlet of the charging unit, and the charging outlet of the molten salt energy storage unit is connected to the medium inlet of the charging unit. The energy release unit has its molten salt inlet connected to the outlet of the high-temperature molten salt tank, its molten salt outlet connected to the inlet of the low-temperature molten salt tank, its feedwater inlet connected to the feedwater pipeline of the turbine unit and the power generation system, and its feedwater outlet connected to the feedwater inlet of the boiler. The high-temperature thermal energy of the molten salt is used to further heat the feedwater, thereby increasing the heat absorption temperature of the boiler feedwater and improving the unit efficiency.

[0012] Furthermore, the charging unit includes: A steam-molten salt heat exchanger, wherein the heat working fluid inlet of the steam-molten salt heat exchanger is connected to the steam extraction port of the steam turbine unit and the power generation system, the heat working fluid outlet of the steam-molten salt heat exchanger is connected to the steam supply unit, the medium outlet of the steam-molten salt heat exchanger is connected to the inlet of the high-temperature molten salt tank, and the medium inlet of the steam-molten salt heat exchanger is connected to the outlet of the low-temperature molten salt tank; The pressure matching device has its working fluid inlet connected to the steam extraction port of the turbine unit and the power generation system, and its working fluid outlet connected to the hot working fluid inlet of the steam supply unit and the steam-molten salt heat exchanger, respectively.

[0013] Furthermore, the energy-releasing unit includes: A feedwater-molten salt heat exchanger is provided, wherein the molten salt inlet of the feedwater-molten salt heat exchanger is connected to the outlet of the high-temperature molten salt tank, the molten salt outlet of the feedwater-molten salt heat exchanger is connected to the inlet of the low-temperature molten salt tank, the feedwater inlet of the feedwater-molten salt heat exchanger is connected to the outlet of the high-pressure heater, and the feedwater outlet of the feedwater-molten salt heat exchanger is connected to the feedwater inlet of the boiler.

[0014] Furthermore, the molten salt energy storage unit also includes: A high-temperature molten salt pump is installed on the outlet pipeline of the high-temperature molten salt tank; A cryogenic molten salt pump is installed on the outlet pipeline of the cryogenic molten salt tank.

[0015] Furthermore, the charging unit also includes a valve piping assembly, which includes: The first valve is located between the hot section reheat steam extraction port and the working fluid inlet of the steam-molten salt heat exchanger; the second valve is located between the main steam extraction port and the working fluid inlet of the pressure matcher; the third valve is located between the hot section reheat steam extraction port and the working fluid inlet of the pressure matcher; and the fourth valve is located between the cold section reheat steam extraction port and the working fluid inlet of the pressure matcher. The fifth valve is located between the working fluid outlet of the pressure matcher and the steam supply header; the sixth valve is located between the intermediate pressure cylinder exhaust steam extraction port and the working fluid inlet of the pressure matcher; the seventh valve is located between the hot section reheat steam extraction port and the hot working fluid inlet of the steam-molten salt heat exchanger; and the eighth valve is located between the outlet of the low-temperature molten salt tank and the medium inlet of the steam-molten salt heat exchanger. The ninth valve is located between the outlet of the high-temperature molten salt tank and the molten salt inlet of the energy release unit; the tenth valve is located between the working fluid outlet of the pressure matching device and the hot working fluid inlet of the steam-molten salt heat exchanger; and the eleventh valve is located between the hot working fluid outlet of the steam-molten salt heat exchanger and the cold section reheat steam pipeline.

[0016] In a second aspect, this invention proposes a thermal power-molten salt energy storage coupling method for synergistically achieving energy-saving heating and flexible peak shaving, applied to the system described in the first aspect. This method, by switching the on / off states of valves on various pipelines, enables the system to execute any of the following operating modes: First mode: Connect the pipeline between the charging unit and the hot section reheat steam extraction port of the turbine unit and power generation system, and connect the pipeline between the outlet of the high temperature molten salt tank and the molten salt inlet of the energy release unit, so that the hot section reheat steam heats the low temperature molten salt, while the high temperature molten salt heats the boiler feedwater. Second mode: Connect the pipeline between the charging unit and the main steam extraction port of the turbine unit and power generation system, and shut off the pipeline between the outlet of the high-temperature molten salt tank and the molten salt inlet of the energy release unit, so that the mixed steam formed by the reheat steam of the main steam ejector section heats the low-temperature molten salt and stops the high-temperature molten salt from releasing heat. Third mode: shut off the steam pipeline between the energy charging unit and the steam turbine unit and the power generation system, and open the pipeline between the outlet of the high-temperature molten salt tank and the molten salt inlet of the energy release unit, so that the high-temperature molten salt heats the boiler feedwater.

[0017] Furthermore, the first mode includes: The first valve, the eighth valve, and the ninth valve are opened so that the hot section reheat steam enters the steam-molten salt heat exchanger through the first valve to heat the low-temperature molten salt from the low-temperature molten salt tank. The hot section reheat steam after heat release enters the steam supply header, while the high-temperature molten salt enters the feedwater-molten salt heat exchanger through the ninth valve to heat the boiler feedwater.

[0018] Furthermore, the second mode includes: The second valve, the third valve, the eighth valve, the tenth valve, and the eleventh valve are opened so that the main steam is drawn through the second valve into the hot section reheat steam entering through the third valve to form mixed steam. The mixed steam enters the steam-molten salt heat exchanger through the tenth valve to heat the low-temperature molten salt from the low-temperature molten salt tank. After releasing heat, part of the mixed steam returns to the cold section reheat steam pipeline through the eleventh valve, and the remaining part enters the steam supply header.

[0019] Furthermore, the first mode also includes: The fourth, fifth, and sixth valves are opened so that the cold section reheat steam enters the pressure matching device through the fourth valve, and the exhaust steam from the intermediate pressure cylinder that enters through the sixth valve is ejected to form mixed steam. The mixed steam enters the steam supply header through the fifth valve and merges with the hot section reheat steam after heat release for steam supply.

[0020] Furthermore, the first mode also includes: The seventh valve is opened so that the hot section reheat steam enters the steam-molten salt heat exchanger through the first valve and the seventh valve to heat the low temperature molten salt. The hot section reheat steam and the cold section reheat steam after heat release merge into the steam supply header.

[0021] The beneficial effects of this invention are: This invention sets up an energy charging unit, a molten salt energy storage unit, and an energy release unit, and connects the energy charging unit to the steam turbine extraction port and the steam supply unit respectively, and the energy release unit to the boiler feedwater pipeline. This allows the unit to store part of the thermal energy of the main steam or reheat steam in the molten salt medium under low load conditions, thereby reducing the unit's power output. At the same time, during non-peak periods, the stored thermal energy is released to the boiler feedwater system, reducing boiler fuel consumption and achieving decoupled operation of the unit's electrical load and thermal load.

[0022] This invention, by incorporating a steam-molten salt heat exchanger and a pressure matcher within the energy charging unit, and configuring a valve piping assembly consisting of valves one through eleven, allows the system to flexibly switch steam sources and working fluid flow paths according to grid dispatch instructions and heating demands. Specifically, by opening or closing different valve combinations, the system can operate in various modes, including using reheated steam from the hot section to store superheat before supplying steam, using main steam to inject reheated steam from the hot section for pure energy storage, and using high-temperature molten salt for pure energy release. This broadens the unit's operating load range and adapts to different peak-shaving depth requirements.

[0023] This invention connects the heat exchanger outlet of a steam-molten salt heat exchanger to a steam supply unit, and directly uses the released steam for external steam supply, replacing the traditional method of directly extracting steam and then spraying water for desuperheating. The temperature of the released steam has been reduced to the required steam supply parameters through the molten salt heat exchange process, avoiding irreversible heat loss caused by the water spray desuperheating process.

[0024] This invention utilizes a feedwater-molten salt heat exchanger to heat the boiler feedwater at the outlet of the high-pressure heater by storing heat in the high-temperature molten salt. This allows some of the heat to be returned to the thermal system for recycling and work, reducing the heat load demand on the boiler side and thus lowering the unit's coal consumption for power generation while maintaining the same power output.

[0025] The system structure of this invention is based on the existing thermal power unit thermal system and is coupled together. The energy charging unit and the energy releasing unit are connected to the steam turbine extraction port, the steam supply main pipe and the feedwater pipeline of the regenerating system through pipeline valves. No major modifications are made to the steam turbine body and the boiler body. The engineering implementation is highly feasible and it is suitable for the flexible retrofitting of in-service thermal power units. Attached Figure Description

[0026] Other features, objects, and advantages of this application will become more apparent from the following detailed description of non-limiting embodiments with reference to the accompanying drawings: Figure 1 This is a schematic diagram of the overall structure of a thermal power-molten salt energy storage coupling system that synergistically achieves energy-saving heating and flexible peak shaving, provided by the present invention. Figure 2This is a schematic diagram of the specific structure of a thermal power-molten salt energy storage coupling system that synergistically achieves energy-saving heating and flexible peak shaving, provided by the present invention. Figure 3 This is a schematic diagram of a control method under high load conditions for a thermal power-molten salt energy storage coupling method that synergistically achieves energy-saving heating and flexible peak shaving, provided by the present invention. Figure 4 This is a schematic diagram of the control method under low load conditions in a thermal power-molten salt energy storage coupling method that synergistically achieves energy-saving heating and flexible peak shaving provided by the present invention; Figure 5 This is a schematic diagram of a control method under extremely low load conditions for a thermal power-molten salt energy storage coupling method that synergistically achieves energy-saving heating and flexible peak shaving, provided by the present invention. Figure 6 This is a schematic diagram of a control method under extremely low load conditions for a thermal power-molten salt energy storage coupling method that synergistically achieves energy-saving heating and flexible peak shaving, provided by the present invention. Figure 7 This is a schematic diagram of a control method under non-extremely low load conditions for a thermal power-molten salt energy storage coupling method that synergistically achieves energy-saving heating and flexible peak shaving, provided by the present invention.

[0027] In the diagram: 1-Steam turbine unit and power generation system; 2-Energy charging unit; 3-Molten salt energy storage unit; 4-Energy release unit; 5-Steam supply unit; 6-Boiler; 7-Steam turbine unit; 8-Generator; 9-Condenser; 10-Deaerator; 11-Steam-molten salt heat exchanger; 12-Pressure matching device; 13-High-temperature molten salt tank; 14-Low-temperature molten salt tank; 15-Feedwater-molten salt heater; 16-High-pressure heater; 17-Low-pressure heater; 18-Deaerator outlet water pump; 19-Condenser outlet water pump; 20-High temperature molten salt pump; 21-Low temperature molten salt pump; 30 - First valve; 31 - Second valve; 32 - Third valve; 33 - Fourth valve; 34 - Fifth valve; 35 - Sixth valve; 36 - Seventh valve; 37 - Eighth valve; 38 - Ninth valve; 39 - Tenth valve; 40 - Eleventh valve. Detailed Implementation

[0028] The present application will now be described in further detail with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the invention. Furthermore, it should be noted that, for ease of description, only the parts relevant to the invention are shown in the accompanying drawings.

[0029] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. This application will now be described in detail with reference to the accompanying drawings and embodiments.

[0030] The first embodiment of the present invention provides a thermal power-molten salt energy storage coupling system that synergistically achieves energy-saving heating and flexible peak shaving, including a steam turbine unit and a power generation system 1, and further including: The charging unit 2 has its working fluid inlet connected to the steam extraction port of the turbine generator set and power generation system 1, and its working fluid outlet connected to the steam supply unit 5. The charging unit 2 is used to transfer part of the excess heat energy of the extracted steam to the molten salt medium for storage, and to transfer the extracted steam to the steam supply unit 5. Molten salt energy storage unit 3 includes a high-temperature molten salt tank 13 and a low-temperature molten salt tank 14. The charging inlet of the molten salt energy storage unit 3 is connected to the medium outlet of the charging unit 2, and the charging outlet of the molten salt energy storage unit 3 is connected to the medium inlet of the charging unit 2. The energy release unit 4 has a molten salt inlet connected to the outlet of the high-temperature molten salt tank 13, a molten salt outlet connected to the inlet of the low-temperature molten salt tank 14, a water supply inlet connected to the water supply pipeline of the steam turbine unit and power generation system 1, and a water supply outlet connected to the water supply inlet of the boiler 6.

[0031] like Figure 1 and Figure 2 As shown, the steam turbine unit and power generation system 1 includes a boiler 6, a steam turbine 7, and a generator 8. The main steam generated by the boiler 6 enters the high-pressure cylinder of the steam turbine 7 to perform work. The exhaust steam from the high-pressure cylinder returns to the reheater of the boiler 6 and is reheated into hot-section reheat steam. It then enters the intermediate-pressure and low-pressure cylinders of the steam turbine 7 to continue performing work, driving the generator 8 to generate electricity. The exhaust steam from the steam turbine 7 enters the condenser 9 and condenses into water. The condensate is pressurized by the condenser outlet pump 19 and flows sequentially through the low-pressure heater 17 into the deaerator 10. The deaerated feedwater is pressurized by the deaerator outlet pump 18, heated by the high-pressure heater 16, and returned to the boiler 6 as boiler feedwater, forming a complete thermodynamic cycle. The working fluid inlet of the charging unit 2 is connected to the extraction ports of each stage of the steam turbine 7, including the main steam extraction port, the hot-section reheat steam extraction port, the cold-section reheat steam extraction port, and the intermediate-pressure cylinder exhaust steam extraction port. The charging unit 2 receives the high-temperature steam drawn from the extraction port, allowing the steam to exchange heat with the low-temperature molten salt from the low-temperature molten salt tank 14. Part of the heat energy carried by the steam is transferred to the molten salt medium. After the steam's temperature decreases, it is delivered to the steam supply unit 5 through the working fluid outlet to meet the steam demand of industrial or heating users. The high-temperature molten salt tank 13 in the molten salt energy storage unit 3 stores the high-temperature molten salt formed after heating by the charging unit 2, while the low-temperature molten salt tank 14 stores the low-temperature molten salt after heat release.

[0032] The working medium in both the low-temperature molten salt tank 14 and the high-temperature molten salt tank 13 is Hitec ternary molten salt. The storage temperature range of the low-temperature molten salt tank 14 is 190℃ to 200℃, and the storage temperature range of the high-temperature molten salt tank 13 is 385℃ to 395℃. The molten salt inlet of the energy release unit 4 is connected to the outlet of the high-temperature molten salt tank 13, receiving the high-temperature molten salt and transferring its heat to the boiler feedwater, further increasing the feedwater temperature before it enters the boiler 6. The heat-released low-temperature molten salt returns to the low-temperature molten salt tank 14 through the molten salt outlet of the energy release unit 4, completing the molten salt energy release cycle. Utilizing the high-grade steam of the turbine unit 7 as the heat source for the energy charging unit 2 reduces the consumption of high-grade energy by the turbine unit and the power generation system 1, and allows for a reduction in unit output when needed, fully utilizing low-grade heat energy to reduce coal consumption. The above system structure integrates the three functional units of energy charging, energy storage and energy release into the thermal system of existing thermal power units through pipeline valves, realizing the time-sharing storage and on-demand release of steam thermal energy, and providing the unit with an additional dimension of energy regulation.

[0033] As a further explanation of the present invention, the energy charging unit 2 includes: a steam-molten salt heat exchanger 11, wherein the working fluid inlet of the steam-molten salt heat exchanger 11 is connected to the steam extraction port of the turbine unit and power generation system 1, the working fluid outlet of the steam-molten salt heat exchanger 11 is connected to the steam supply unit 5, the medium outlet of the steam-molten salt heat exchanger 11 is connected to the inlet of the high-temperature molten salt tank 13, and the medium inlet of the steam-molten salt heat exchanger 11 is connected to the outlet of the low-temperature molten salt tank 14; and a pressure matching device 12, wherein the working fluid inlet of the pressure matching device 12 is connected to the steam extraction port of the turbine unit and power generation system 1, and the working fluid outlet of the pressure matching device 12 is connected to both the steam supply unit 5 and the working fluid inlet of the steam-molten salt heat exchanger 11.

[0034] like Figure 2As shown, the steam-molten salt heat exchanger 11 is a shell-and-tube heat exchanger, with molten salt flowing through the tubes and steam flowing through the shell. High-temperature steam extracted from the steam turbine 7 enters the shell side of the steam-molten salt heat exchanger 11 through the working fluid inlet, where it undergoes indirect heat exchange with the low-temperature molten salt entering the tube side from the medium inlet. The steam cools down during the heat release process, and the cooled steam exits from the working fluid outlet and enters the steam supply header of the steam supply unit 5. Simultaneously, the low-temperature molten salt absorbs heat from the steam, raising its temperature to above 385°C, and flows out from the medium outlet into the high-temperature molten salt tank 13 for storage. The pressure matching device 12 is a jet-type thermal compressor, which works by using high-pressure working steam to inject low-pressure steam, mixing them in the mixing chamber to obtain a mixed steam at an intermediate pressure. The working fluid inlet of the pressure matcher 12 can be connected to main steam, hot-section reheat steam, cold-section reheat steam, or intermediate-pressure cylinder exhaust steam, depending on operational needs. Part of the mixed steam output from the working fluid outlet can be directly supplied to the steam header for external steam supply, while the other part can be used as a heat source to heat the molten salt in the steam-molten salt heat exchanger 11. By coordinating the operation of the steam-molten salt heat exchanger 11 and the pressure matcher 12, the system can adapt to changes in steam parameters under different load conditions. It can utilize high-parameter steam to heat the molten salt for energy storage, and the pressure matcher 12 can adjust the steam parameters to meet the steam quality requirements of different heat users, thus broadening the system's operational adaptability.

[0035] As a further explanation of the present invention, the energy release unit 4 includes: a feedwater-molten salt heat exchanger 15, wherein the molten salt inlet of the feedwater-molten salt heat exchanger 15 is connected to the outlet of the high-temperature molten salt tank 13, the molten salt outlet of the feedwater-molten salt heat exchanger 15 is connected to the inlet of the low-temperature molten salt tank 14, the feedwater inlet of the feedwater-molten salt heat exchanger 15 is connected to the outlet of the high-pressure heater 16, and the feedwater outlet of the feedwater-molten salt heat exchanger 15 is connected to the feedwater inlet of the boiler 6.

[0036] like Figure 2As shown, the feedwater-molten salt heat exchanger 15 also adopts a shell-and-tube structure, with the tube side flowing through the molten salt and the shell side flowing through the feedwater. Along the molten salt flow direction, the high-temperature molten salt tank 13, the high-temperature molten salt pump 20, the feedwater-molten salt heat exchanger 15, and the low-temperature molten salt tank 14 are connected in sequence. The high-temperature molten salt is drawn from the outlet of the high-temperature molten salt tank 13 and enters the tube side of the feedwater-molten salt heat exchanger 15 through the molten salt inlet. It exchanges heat with the boiler feedwater from the outlet of the high-pressure heater 16 in the shell side. After transferring heat to the feedwater, the temperature of the high-temperature molten salt decreases to approximately 200°C, flows out from the molten salt outlet, and returns to the low-temperature molten salt tank 14 for storage. The boiler feedwater, heated to a certain temperature by the turbine extraction steam in the high-pressure heater 16, further absorbs heat from the high-temperature molten salt after entering the feedwater-molten salt heat exchanger 15, causing its temperature to rise again. It then enters the economizer inlet of the boiler 6 through the feedwater outlet. Because the temperature of the feedwater increases before entering boiler 6, the amount of fuel required for boiler 6 to achieve the same main steam parameters is reduced accordingly, thus lowering the boiler's heat load and achieving a decrease in the unit's coal consumption for power generation while maintaining the same power output. Connecting the feedwater-molten salt heat exchanger 15 in series between the high-pressure heater 16 and boiler 6 fully utilizes the existing pipeline interfaces of the thermal power unit's regenerative system, requiring minimal modification work and facilitating project implementation.

[0037] As a further explanation of the present invention, the molten salt energy storage unit 3 further includes: a high-temperature molten salt pump 20, which is installed on the outlet pipeline of the high-temperature molten salt tank 13; and a low-temperature molten salt pump 21, which is installed on the outlet pipeline of the low-temperature molten salt tank 14.

[0038] like Figure 2 As shown, both the high-temperature molten salt pump 20 and the low-temperature molten salt pump 21 are vertical submersible centrifugal pumps, with the pump body submerged below the molten salt surface. The impellers and flow-through components are made of high-temperature and corrosion-resistant alloy materials. The high-temperature molten salt pump 20 is located at the outlet end of the high-temperature molten salt tank 13, used to pressurize the high-temperature molten salt in the tank and deliver it to the feedwater-molten salt heat exchanger 15, overcoming the flow resistance of the pipeline and heat exchanger to ensure a stable and adjustable molten salt flow rate during energy release. The low-temperature molten salt pump 21 is located at the outlet end of the low-temperature molten salt tank 14, used to pressurize the low-temperature molten salt in the tank and deliver it to the steam-molten salt heat exchanger 11, overcoming the pipeline resistance on the molten salt side to ensure a stable supply of molten salt flow rate during charging. The speed of both molten salt pumps can be adjusted via frequency converters to achieve continuous adjustment of charging and releasing power, matching the needs of variable load operation of the unit. By setting up an independent molten salt delivery pump set, the driving force of molten salt circulation does not depend on the pressure difference of other components in the system, ensuring the independence and reliability of the energy charging and releasing process, promoting the normal flow of molten salt, and thus ensuring the heat exchange effect.

[0039] As a further explanation of the present invention, the charging unit 2 also includes a valve pipeline assembly, which includes: a first valve 30, disposed between the hot section reheat steam extraction port and the working fluid inlet of the steam-molten salt heat exchanger 11; a second valve 31, disposed between the main steam extraction port and the working fluid inlet of the pressure matching device 12; a third valve 32, disposed between the hot section reheat steam extraction port and the working fluid inlet of the pressure matching device 12; a fourth valve 33, disposed between the cold section reheat steam extraction port and the working fluid inlet of the pressure matching device 12; a fifth valve 34, disposed between the working fluid outlet of the pressure matching device 12 and the steam supply header; and a sixth valve 35, disposed in the middle section... The seventh valve 36 is located between the exhaust steam port of the pressure matching device 12 and the working medium inlet of the steam-molten salt heat exchanger 11; the eighth valve 37 is located between the outlet of the low-temperature molten salt tank 14 and the medium inlet of the steam-molten salt heat exchanger 11; the ninth valve 38 is located between the outlet of the high-temperature molten salt tank 13 and the molten salt inlet of the energy release unit 4; the tenth valve 39 is located between the working medium outlet of the pressure matching device 12 and the working medium inlet of the steam-molten salt heat exchanger 11; and the eleventh valve 40 is located between the working medium outlet of the steam-molten salt heat exchanger 11 and the cold section reheat steam pipeline.

[0040] like Figure 2As shown, the first valve 30 to the eleventh valve 40 are all electrically operated or pneumatically operated regulating valves, equipped with remote on / off control and opening adjustment functions, and can be connected to the unit's distributed control system for automatic control. The arrangement and function of each valve are as follows: First valve 30 controls the passage for hot-section reheat steam to directly enter the steam-molten salt heat exchanger 11; second valve 31 controls the passage for main steam to enter the pressure matching device 12 as working steam; third valve 32 controls the passage for hot-section reheat steam to enter the pressure matching device 12 as ejected steam; fourth valve 33 controls the passage for cold-section reheat steam to enter the pressure matching device 12 as working steam; fifth valve 34 controls the passage for mixed steam from the outlet of the pressure matching device 12 to enter the steam supply header; sixth valve 35 controls the passage for intermediate-pressure cylinder exhaust steam to enter the pressure matching device 12 as ejected steam. The steam path includes a seventh valve 36 connected in parallel with the first valve 30, controlling another path for the hot section reheat steam to enter the steam-molten salt heat exchanger 11 to increase the flow area. An eighth valve 37 controls the path for low-temperature molten salt to enter the steam-molten salt heat exchanger 11 from the low-temperature molten salt tank 14. A ninth valve 38 controls the path for high-temperature molten salt to enter the feedwater-molten salt heat exchanger 15 from the high-temperature molten salt tank 13. A tenth valve 39 controls the path for the mixed steam from the outlet of the pressure matcher 12 to enter the steam-molten salt heat exchanger 11. An eleventh valve 40 controls the path for the steam released from the outlet of the steam-molten salt heat exchanger 11 to return to the cold section reheat steam pipeline. Through the configuration of these valve and pipeline components, the system can flexibly combine the steam source, molten salt flow path, and feedwater heating path according to the needs of the operating mode, realizing flexible switching of energy storage, energy release, and steam supply functions under various operating conditions.

[0041] The second embodiment of the present invention also provides a thermal power-molten salt energy storage coupling method for synergistically achieving energy-saving heating and flexible peak shaving. Applied to the above-mentioned system, by switching the on / off state of valves on each pipeline, the system can execute any of the following operating modes: First mode: Connect the pipeline between the charging unit 2 and the hot section reheat steam extraction port of the turbine unit and power generation system 1, and connect the pipeline between the outlet of the high temperature molten salt tank 13 and the molten salt inlet of the energy release unit 4, so that the hot section reheat steam heats the low temperature molten salt, and the high temperature molten salt heats the boiler feedwater at the same time. Second mode: Connect the pipeline between the charging unit 2 and the main steam extraction port of the turbine unit and power generation system 1, and shut off the pipeline between the outlet of the high-temperature molten salt tank 13 and the molten salt inlet of the energy release unit 4, so that the mixed steam formed by the reheat steam of the main steam ejector section heats the low-temperature molten salt and stops the high-temperature molten salt from releasing heat. Third mode: shut off the steam pipeline between the energy charging unit 2 and the steam turbine unit and power generation system 1, and open the pipeline between the outlet of the high-temperature molten salt tank 13 and the molten salt inlet of the energy release unit 4, so that the high-temperature molten salt heats the boiler feedwater.

[0042] In this embodiment, the three operating modes correspond to the typical working states of the unit under different grid dispatch instructions and heating demands. The first mode is a cyclic mode in which heat storage and release occur simultaneously, suitable for the unit when it is in a high load range and the grid requires the unit to maintain a certain output while also meeting the requirement of external steam supply. In this mode, some steam is extracted from the hot section reheat steam extraction port of the steam turbine 7 and enters the charging unit 2 to heat the low-temperature molten salt. The released steam enters the steam supply header for external steam supply. At the same time, the high-temperature molten salt in the high-temperature molten salt tank 13 enters the energy release unit 4 to heat the boiler feedwater. Due to the increase in boiler feedwater temperature, the amount of fuel required by the boiler 6 is reduced, and the coal consumption for power generation is reduced for the same power output.

[0043] The second mode is a pure energy storage mode, suitable for operating conditions where the grid load is extremely low and dispatching requires the unit to deeply reduce its output. In this mode, high-pressure steam is drawn from the main steam extraction port as working steam, and hot section reheat steam is injected. The resulting mixed steam is used entirely to heat the low-temperature molten salt. Part of the steam after heat release is returned to the cold section reheat steam pipeline to protect the boiler reheater from overheating, and the remainder enters the steam supply header. At the same time, the ninth valve 38 is closed, the high-temperature molten salt stops releasing heat, and the molten salt energy storage unit 3 only performs energy charging operations, converting the unit's excess output into molten salt thermal energy storage.

[0044] The third mode is a pure energy release mode, suitable for situations where the grid load is high, the unit needs to increase output, but the boiler fuel supply is limited. In this mode, the steam pipelines of the charging unit 2 and the turbine are completely shut off, and steam is no longer extracted from the unit for energy storage; only the ninth valve 38 is opened, and high-temperature molten salt enters the energy release unit 4 to heat the boiler feedwater, using the stored heat energy to replace part of the boiler fuel consumption, thereby increasing the unit's grid-connected power output. The above three modes can be achieved by switching valves, with a fast response speed, adapting to the real-time requirements of grid peak shaving and frequency regulation.

[0045] The first mode includes: opening the first valve 30, the eighth valve 37, and the ninth valve 38, so that the hot section reheat steam enters the steam-molten salt heat exchanger 11 through the first valve 30 to heat the low-temperature molten salt from the low-temperature molten salt tank 14, and the hot section reheat steam after heat release enters the steam supply header, while the high-temperature molten salt enters the feedwater-molten salt heat exchanger 15 through the ninth valve 38 to heat the boiler feedwater.

[0046] like Figure 4As shown, a specific valve operation mode in the first mode corresponds to the system being under medium-low load conditions. First valve 30, seventh valve 36, eighth valve 37, and ninth valve 38 are opened, while second valve 31, third valve 32, fourth valve 33, fifth valve 34, sixth valve 35, tenth valve 39, and eleventh valve 40 are closed. The cryogenic molten salt pump 21 is started, allowing cryogenic molten salt to enter the medium inlet of the steam-molten salt heat exchanger 11 from the cryogenic molten salt tank 14 via the eighth valve 37. Hot-section reheat steam is drawn from the hot-section reheat steam extraction port of the steam turbine 7, enters the hot working medium inlet of the steam-molten salt heat exchanger 11 via first valve 30 and seventh valve 36, heats the cryogenic molten salt within the heat exchanger, and the released hot-section reheat steam mixes with the cold-section reheat steam and enters the steam supply header for steam supply. The heated cryogenic molten salt is stored in the high-temperature molten salt tank 13. On the energy release side, the high-temperature molten salt pump 20 is started, allowing high-temperature molten salt to enter the feedwater-molten salt heat exchanger 15 from the high-temperature molten salt tank 13 via the ninth valve 38. This heats the boiler feedwater from the high-pressure heater 16, and the released molten salt is stored in the low-temperature molten salt tank 14. This valve combination enables simultaneous and continuous operation of heat storage and release. Utilizing molten salt as an intermediate medium, part of the heat energy of the hot section reheat steam is transferred to the boiler feedwater via molten salt, while the other part of the steam is directly supplied after cooling. This avoids the energy loss caused by water spraying for desuperheating in traditional direct steam extraction and supply, while the increased boiler feedwater temperature reduces fuel consumption.

[0047] The first mode further includes: opening the seventh valve 36 so that the hot section reheat steam enters the steam-molten salt heat exchanger 11 through the first valve 30 and the seventh valve 36 to heat the low temperature molten salt, and the hot section reheat steam and cold section reheat steam merge into the steam supply header after heat release.

[0048] like Figure 4 As shown, this valve operation mode also corresponds to the system being under medium-low load conditions. Based on the first mode where valves 30, 37, and 38 are already open, valve 36 is further opened. At this time, the hot-section reheat steam simultaneously enters the working fluid inlet of the steam-molten salt heat exchanger 11 through two parallel pathways: valve 30 and valve 36. This increases the steam flow area and meets the steam supply capacity requirements of high-flow-rate energy storage. After releasing heat, the hot-section reheat steam exits from the working fluid outlet of the steam-molten salt heat exchanger 11 and merges with the cold-section reheat steam, jointly entering the steam supply header for external steam supply. This valve combination is suitable for units operating in the medium-low load range where the hot-section reheat steam parameters decrease but the energy storage and steam supply demands remain high. By setting valves 30 and 36 in parallel, sufficient steam mass flow rate can still be ensured to enter the heat exchanger when the steam pressure decreases, maintaining the energy storage power. The released steam is directly mixed with the cold section reheat steam for steam supply, which simplifies the system operation process and reduces the workload of the pressure matcher 12.

[0049] The first mode further includes: opening the fourth valve 33, the fifth valve 34 and the sixth valve 35 so that the cold section reheat steam enters the pressure matching device 12 through the fourth valve 33, and the intermediate pressure cylinder exhaust steam entering through the sixth valve 35 is ejected to form mixed steam. The mixed steam enters the steam supply header through the fifth valve 34 and merges with the hot section reheat steam after heat release for steam supply.

[0050] like Figure 3 As shown, this valve operation mode corresponds to the system being under high load conditions. First valve 30, fourth valve 33, fifth valve 34, sixth valve 35, eighth valve 37, and ninth valve 38 are opened, while second valve 31, third valve 32, seventh valve 36, tenth valve 39, and eleventh valve 40 are closed. The cryogenic molten salt pump 21 is started, allowing the cryogenic molten salt to enter the steam-molten salt heat exchanger 11 for heat exchange. The hot-section reheat steam from the steam turbine 7 heats the cryogenic molten salt in the steam-molten salt heat exchanger 11 via the first valve 30. The released hot-section reheat steam mixes with the mixed steam from the cold-section reheat steam ejected from the intermediate-pressure cylinder and enters the steam supply header for steam supply. The heated cryogenic molten salt is stored in the high-temperature molten salt tank 13. On the energy release side, the high-temperature molten salt pump 20 is started, allowing the high-temperature molten salt to enter the feedwater-molten salt heat exchanger 15 to heat the boiler feedwater, reducing the boiler load. The released high-temperature molten salt is stored in the cryogenic molten salt tank 14. Cold-section reheat steam enters pressure matching device 12 via fourth valve 33 as working steam, while intermediate-pressure cylinder exhaust steam enters pressure matching device 12 via sixth valve 35 as ejected steam. The two mix within pressure matching device 12 to form a mixed steam with suitable parameters, which then enters the steam supply header via fifth valve 34, merging with the released hot-section reheat steam for steam supply. This valve combination is suitable for operating conditions with high unit load and large steam demand. By introducing cold-section reheat steam to eject intermediate-pressure cylinder exhaust steam to form supplementary steam supply, the external steam supply can be increased without affecting the operation of the energy storage heat exchanger, fully tapping the steam supply potential of each stage of the unit's extraction.

[0051] The second mode includes: opening the second valve 31, the third valve 32, the eighth valve 37, the tenth valve 39, and the eleventh valve 40, so that the main steam is drawn through the second valve 31 into the hot section reheat steam entering through the third valve 32 to form mixed steam. The mixed steam enters the steam-molten salt heat exchanger 11 through the tenth valve 39 to heat the low-temperature molten salt from the low-temperature molten salt tank 14. After releasing heat, part of the mixed steam returns to the cold section reheat steam pipeline through the eleventh valve 40, and the remaining part enters the steam supply header.

[0052] like Figure 6As shown, this valve operation mode corresponds to the system being in an extremely low load energy storage mode. The second valve 31, third valve 32, eighth valve 37, tenth valve 39, and eleventh valve 40 are opened, while the first valve 30, fourth valve 33, fifth valve 34, sixth valve 35, seventh valve 36, and ninth valve 38 are closed. Main steam from the main steam extraction port of the steam turbine 7 enters the nozzle of the pressure matching device 12 via the second valve 31 as working steam, generating a high-speed jet that forms a low-pressure zone in the mixing chamber. This jet draws in the hot section reheat steam entering via the third valve 32, and the two are mixed and diffused within the pressure matching device 12 to form a mixed steam at an intermediate pressure. The mixed steam exits from the working fluid outlet of the pressure matching device 12 and enters the hot working fluid inlet of the steam-molten salt heat exchanger 11 via the tenth valve 39. Simultaneously, the cryogenic molten salt pump 21 starts, and cryogenic molten salt enters the medium inlet of the steam-molten salt heat exchanger 11 via the eighth valve 37. The mixed steam releases heat in the heat exchanger, heating the low-temperature molten salt into high-temperature molten salt, which is then stored in the high-temperature molten salt tank 13. The temperature of the released mixed steam decreases, and it exits from the heat medium outlet of the steam-molten salt heat exchanger 11. A portion returns to the cold section reheat steam pipeline via the eleventh valve 40 to increase the steam flow into the boiler 6 reheater and prevent overheating of the reheater tube walls; the remaining portion enters the steam supply header to maintain external steam supply. Because the ninth valve 38 is closed, the energy release unit 4 does not operate, and the system only performs energy charging operations, converting excess unit output into molten salt thermal energy storage, reducing unit output under extremely low load conditions, and expanding the unit's operating load range. This valve combination achieves deep energy storage under extremely low load conditions. By using the main steam to irradiate the hot section reheat steam, it ensures both energy storage power and the safe operation of the boiler reheater through the return of some steam to the cold section reheat steam pipeline, allowing the unit to further reduce power generation output while meeting steam supply requirements.

[0053] The control method also includes a mode of simultaneous operation of heat storage and heat release under extremely low loads, such as... Figure 5As shown. Open valves 31, 32, 37, 38, 39, and 40, and close valves 30, 33, 34, 35, and 36. Start the cryogenic molten salt pump 21 to allow the cryogenic molten salt to enter the steam-molten salt heat exchanger 11 for heat exchange. The mixed steam from the main steam ejector section of the steam turbine 7, after reheating the steam, heats the cryogenic molten salt in the steam-molten salt heat exchanger 11. Part of the released mixed steam returns to the cold section reheat steam, and the remainder enters the steam supply header for steam supply. The heated cryogenic molten salt is stored in the high-temperature molten salt tank 13. On the energy release side, start the high-temperature molten salt pump 20 to allow the high-temperature molten salt to enter the feedwater-molten salt heat exchanger 15 to heat the boiler feedwater, reducing the boiler load. The released high-temperature molten salt is stored in the cryogenic molten salt tank 14. This method achieves the coordinated operation of three functions—heat storage, steam supply, and heat release—under extremely low loads, utilizing molten salt circulation for energy-saving heating and reducing heat loss from direct steam extraction and water spraying for de-cooling.

[0054] The control method also includes a pure energy release operation mode under non-extremely low load conditions, such as... Figure 7 As shown. Under non-extremely low load conditions, the energy stored under extremely low load conditions is released, opening the ninth valve 38 and closing the eighth valve 37. This allows the high-temperature molten salt in the high-temperature molten salt tank 13 to enter the feedwater-molten salt heat exchanger 15 through the ninth valve 38 to heat the boiler feedwater. The released high-temperature molten salt then enters the low-temperature molten salt tank 14 for storage. Because the eighth valve 37 is closed, the energy charging unit 2 stops working, and the system only performs energy release operations, using the stored high-temperature molten salt to heat the boiler feedwater, reducing the boiler load, utilizing molten salt circulation for energy-saving heating, and reducing heat loss from direct steam extraction and water spray desuperheating.

[0055] The specific application conditions for the charging mode are as follows: When the power system load is less than the minimum load under the medium-low load operation mode, the system is in an extremely low load energy storage and steam supply condition, and the molten salt system begins to charge; when the molten salt system is full, the system is in an extremely low load molten salt circulation synchronous operation energy-saving steam supply condition, and the molten salt system maintains a certain flow circulation and no longer charges. The specific application conditions for the energy release mode are as follows: When the power system load is greater than the minimum load under the medium-low load operation mode, the system is in a non-extremely low load energy release mode, releasing molten salt from the high-temperature molten salt tank 13 to heat the feedwater; when the molten salt system releases heat to its minimum capacity, the system is in a medium-low load molten salt circulation synchronous operation energy-saving steam supply condition or a high load molten salt circulation synchronous operation energy-saving steam supply condition, and the molten salt system maintains a certain flow circulation and no longer releases energy.

[0056] Taking a 600MW supercritical cogeneration unit as an example, steam is extracted from the unit to meet industrial steam demand. Under medium to high loads, the cold section reheat steam can be supplied at 60 to 80 t / h using a four-stage extraction system, while the hot section reheat steam can be supplied at 100 to 120 t / h through water spraying for desuperheating. However, under low loads, the reheat steam parameters are too low to meet the steam supply requirements, necessitating the use of main steam extraction to draw hot section reheat steam for desuperheating, resulting in higher energy consumption. After adopting the thermal power-molten salt energy storage coupling system and its control method proposed in this invention to achieve synergistic energy-saving heating and flexible peak regulation, the unit operation modes are as follows: High-load molten salt cycle synchronous operation for energy-saving steam supply corresponds to a load range of 60% THA to 100% THA. Steam is supplied by cold-section reheat steam injection and extraction steam. For any shortfall, hot-section reheat steam is extracted. After the molten salt system stores heat, the steam is mixed with the extracted steam for supply. The heat stored in the molten salt heats the feedwater. Compared to directly using hot-section reheat steam for desuperheating under the same load, the unit coal consumption rate is reduced by 0.5 to 1.0 g / kWh. Medium- and low-load molten salt cycle synchronous operation for energy-saving steam supply corresponds to a load range of 40% THA to 60% THA. Cold-section reheat steam is extracted and mixed with hot-section reheat steam. After the molten salt system stores heat, the mixed steam is supplied. The heat stored in the molten salt heats the feedwater. Compared to directly using hot-section reheat steam for desuperheating under the same load, the unit coal consumption rate is reduced by 1.0 to 2.0 g / kWh. The energy-saving steam supply mode of molten salt circulation synchronous operation at extremely low loads corresponds to a load range of 25% THA to 40% THA. By using reheat steam from the main steam extraction section, coupled with heat storage in the molten salt system, the mixed steam is supplied, and the molten salt stores heat. Compared to using reheat steam from the main steam extraction section for desuperheating under the same load, the unit coal consumption rate is reduced by 3.0 to 4.0 g / kWh. This 600MW supercritical unit, after adopting this invention, saves approximately 12 tons of coal per day. Combined with the extremely low load energy storage mode and the non-extreme low load energy release mode, it can achieve long-term deep peak shaving and further reduce coal consumption of thermal power units under medium and high loads.

[0057] This invention integrates the advantages of traditional thermal power and molten salt energy storage, synergistically achieving the dual goals of energy-saving heating and flexible peak shaving, providing a new approach for industrial steam-powered cogeneration units. Through the main steam extraction technology, deep peak shaving at extremely low loads is achieved while ensuring heating capacity, and thermal energy is stored and released during off-peak periods, reducing energy losses during peak shaving. Using the molten salt system, the heat that would otherwise require water spraying for desuperheating during steam extraction is circulated through molten salt to heat boiler feedwater, increasing feedwater temperature, reducing boiler load, and thus achieving energy-saving heating. The example unit, while ensuring normal steam and heating supply, achieves thermoelectric decoupling, broadens the unit's operating load range, and reduces boiler output, effectively solving the problems of decreased energy efficiency under low load operation and strong thermoelectric correlation. While achieving peak shaving functionality, it also enables the adjustment of the unit's variable load performance. The use of molten salt circulation heating for energy saving improves the unit's thermal efficiency. Based on the existing thermal power units, the inlet flow of each cylinder of the steam turbine was reasonably and effectively adjusted to enhance the steam operation and work capacity, improve operating conditions, and increase the efficiency within the steam turbine unit.

[0058] The terms “first”, “second”, etc., are used to distinguish similar objects, not to describe or indicate a specific order or sequence.

[0059] The term "comprising" or any other similar term is intended to cover non-exclusive inclusion, such that a process, method, article, or apparatus / device that comprises a list of elements includes not only those elements but also other elements not expressly listed, or elements inherent in such process, method, article, or apparatus / device.

[0060] The technical solution of the present invention has been described above with reference to the preferred embodiments shown in the accompanying drawings. However, it will be readily understood by those skilled in the art that the scope of protection of the present invention is obviously not limited to these specific embodiments. Without departing from the principles of the present invention, those skilled in the art can make equivalent changes or substitutions to the relevant technical features, and the technical solutions after these changes or substitutions will all fall within the scope of protection of the present invention.

Claims

1. A thermal power-molten salt energy storage coupling system for synergistically achieving energy-saving heating and flexible peak shaving, comprising a steam turbine unit and a power generation system (1), characterized in that, Also includes: The working fluid inlet of the charging unit (2) is connected to the steam extraction port of the turbine generator set and power generation system (1), and the working fluid outlet of the charging unit (2) is connected to the steam supply unit (5). The charging unit (2) is used to transfer part of the excess heat energy of the extracted steam to the molten salt medium for storage and to transfer the extracted steam to the steam supply unit (5). The molten salt energy storage unit (3) includes a high-temperature molten salt tank (13) and a low-temperature molten salt tank (14). The charging inlet of the molten salt energy storage unit (3) is connected to the medium outlet of the charging unit (2), and the charging outlet of the molten salt energy storage unit (3) is connected to the medium inlet of the charging unit (2). The energy release unit (4) has its molten salt inlet connected to the outlet of the high-temperature molten salt tank (13), its molten salt outlet connected to the inlet of the low-temperature molten salt tank (14), its feedwater inlet connected to the feedwater pipeline of the turbine generator set and power generation system (1), and its feedwater outlet connected to the feedwater inlet of the boiler (6). The high-temperature thermal energy of the molten salt is used to increase the feedwater temperature at the boiler (6).

2. The thermal power-molten salt energy storage coupling system according to claim 1, characterized in that, The charging unit (2) includes: A steam-molten salt heat exchanger (11) is provided. The heat medium inlet of the steam-molten salt heat exchanger (11) is connected to the steam extraction port of the steam turbine unit and power generation system (1). The heat medium outlet of the steam-molten salt heat exchanger (11) is connected to the steam supply unit (5). The medium outlet of the steam-molten salt heat exchanger (11) is connected to the inlet of the high-temperature molten salt tank (13). The medium inlet of the steam-molten salt heat exchanger (11) is connected to the outlet of the low-temperature molten salt tank (14). Pressure matching device (12), the working fluid inlet of the pressure matching device (12) is connected to the steam extraction port of the steam turbine unit and power generation system (1), and the working fluid outlet of the pressure matching device (12) is connected to the hot working fluid inlet of the steam supply unit (5) and the steam-molten salt heat exchanger (11) respectively.

3. The thermal power-molten salt energy storage coupling system according to claim 2, characterized in that, The energy-releasing unit (4) includes: The feedwater-molten salt heat exchanger (15) has its molten salt inlet connected to the outlet of the high-temperature molten salt tank (13), its molten salt outlet connected to the inlet of the low-temperature molten salt tank (14), its feedwater inlet connected to the outlet of the high-pressure heater (16), and its feedwater outlet connected to the feedwater inlet of the boiler (6).

4. The thermal power-molten salt energy storage coupling system according to claim 3, characterized in that, The molten salt energy storage unit (3) also includes: A high-temperature molten salt pump (20) is installed on the outlet pipeline of the high-temperature molten salt tank (13); A cryogenic molten salt pump (21) is installed on the outlet pipeline of the cryogenic molten salt tank (14).

5. The thermal power-molten salt energy storage coupling system according to claim 3, characterized in that, The charging unit (2) further includes a valve piping assembly, which includes: The first valve (30) is located between the hot section reheat steam extraction port and the working medium inlet of the steam-molten salt heat exchanger (11); the second valve (31) is located between the main steam extraction port and the working medium inlet of the pressure matching device (12); the third valve (32) is located between the hot section reheat steam extraction port and the working medium inlet of the pressure matching device (12); and the fourth valve (33) is located between the cold section reheat steam extraction port and the working medium inlet of the pressure matching device (12). The fifth valve (34) is located between the working fluid outlet of the pressure matcher (12) and the steam supply header; the sixth valve (35) is located between the steam extraction port of the intermediate pressure cylinder and the working fluid inlet of the pressure matcher (12); the seventh valve (36) is located between the reheat steam extraction port of the hot section and the hot working fluid inlet of the steam-molten salt heat exchanger (11); the eighth valve (37) is located between the outlet of the low-temperature molten salt tank (14) and the medium inlet of the steam-molten salt heat exchanger (11). The ninth valve (38) is located between the outlet of the high-temperature molten salt tank (13) and the molten salt inlet of the energy release unit (4); the tenth valve (39) is located between the working fluid outlet of the pressure matching device (12) and the hot working fluid inlet of the steam-molten salt heat exchanger (11); the eleventh valve (40) is located between the hot working fluid outlet of the steam-molten salt heat exchanger (11) and the cold section reheat steam pipeline.

6. A method for synergistically achieving energy-saving heating and flexible peak shaving through a thermal power-molten salt energy storage coupling, applied to the system described in claim 5, characterized in that, By switching the on / off state of the valves on each pipeline, the system can be made to operate in any of the following modes: First mode: Connect the pipeline between the charging unit (2) and the hot section reheat steam extraction port of the turbine unit and power generation system (1), and connect the pipeline between the outlet of the high temperature molten salt tank (13) and the molten salt inlet of the energy release unit (4), so that the hot section reheat steam heats the low temperature molten salt, and the high temperature molten salt heats the boiler feedwater at the same time. Second mode: Connect the pipeline between the charging unit (2) and the main steam extraction port of the turbine unit and power generation system (1), and shut off the pipeline between the outlet of the high temperature molten salt tank (13) and the molten salt inlet of the energy release unit (4), so that the mixed steam formed by the reheat steam of the main steam ejector section heats the low temperature molten salt and stops the high temperature molten salt from releasing heat. Third mode: shut off the steam pipeline between the charging unit (2) and the turbine unit and power generation system (1), and open the pipeline between the outlet of the high temperature molten salt tank (13) and the molten salt inlet of the energy release unit (4) so ​​that the high temperature molten salt heats the boiler feedwater.

7. The method according to claim 6, characterized in that, The first mode includes: The first valve (30), the eighth valve (37), and the ninth valve (38) are turned on so that the hot section reheat steam enters the steam-molten salt heat exchanger (11) through the first valve (30) to heat the low temperature molten salt from the low temperature molten salt tank (14). The hot section reheat steam after heat release enters the steam supply header, and at the same time, the high temperature molten salt enters the feedwater-molten salt heat exchanger (15) through the ninth valve (38) to heat the boiler feedwater.

8. The method according to claim 6, characterized in that, The second mode includes: The second valve (31), the third valve (32), the eighth valve (37), the tenth valve (39), and the eleventh valve (40) are opened so that the main steam is drawn through the second valve (31) into the hot section reheat steam entering through the third valve (32) to form mixed steam. The mixed steam enters the steam-molten salt heat exchanger (11) through the tenth valve (39) to heat the low temperature molten salt from the low temperature molten salt tank (14). After the heat is released, part of the mixed steam returns to the cold section reheat steam pipeline through the eleventh valve (40), and the remaining part enters the steam supply header.

9. The method according to claim 7, characterized in that, The first mode also includes: The fourth valve (33), the fifth valve (34), and the sixth valve (35) are opened so that the cold section reheat steam enters the pressure matching device (12) through the fourth valve (33), and the intermediate pressure cylinder exhaust steam entering through the sixth valve (35) is ejected to form mixed steam. The mixed steam enters the steam supply header through the fifth valve (34) and merges with the hot section reheat steam after heat release for steam supply.

10. The method according to claim 7, characterized in that, The first mode also includes: The seventh valve (36) is turned on so that the hot section reheat steam enters the steam-molten salt heat exchanger (11) through the first valve (30) and the seventh valve (36) to heat the low temperature molten salt. The hot section reheat steam and the cold section reheat steam after heat release merge into the steam supply header.

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