A molten salt heat storage method capable of energy cascade utilization

Abstract

The application discloses a molten salt heat storage method with energy cascade utilization, and according to different power grid peak regulation demands, a heat storage system is operated in a matched mode; with the increase of the peak regulation demand, a reheating heat section to the heat storage system, main steam to the heat storage system and an electric heater are gradually started; the molten salt heat storage method utilizes the combined action of a molten salt storage tank, a water storage tank and electric heating to achieve the purpose of efficient energy storage, meets the peak regulation and frequency modulation demands of different modes of a unit and is good in economy.

Description

Technical Field

[0001] This invention relates to the field of energy storage technology, and more particularly to the field of steam extraction and electrically heated molten salt energy storage technology. Background Technology

[0002] In recent years, steam extraction molten salt energy storage has become a new type of energy storage method. With its flexible system configuration, it can meet the peak shaving and frequency regulation functions of generating units and power grids, and has been vigorously developed and researched.

[0003] There are many technical routes for steam extraction molten salt energy storage, which can be broadly divided into two categories. The first category involves main steam extraction condensing into water after passing through a molten salt heat exchanger. This water is then pumped back to the original high-pressure feedwater pipeline via a pressure boosting ratio. Reheat hot-section extraction steam is cooled by a molten salt heat exchanger, then pressurized by a steam compressor or ejected from the main steam via a pressure matching device, and finally discharged to the reheat cold-section pipeline. The second category involves main steam extraction being cooled to cold-section parameters by a molten salt heat exchanger before entering the cold-section pipeline. Reheat hot-section extraction steam is cooled to intermediate-pressure cylinder exhaust parameters by a molten salt heat exchanger before entering the low-pressure cylinder to perform work.

[0004] The first type of scheme maximizes the utilization of the latent and sensible heat of steam during thermal storage, resulting in a high peak-shaving capacity. However, its drawbacks include the high manufacturing difficulty and cost of the steam compressor, leading to poor economic efficiency. Furthermore, the pressure matching device exhibits poor reliability under operating conditions deviating from design specifications, making it difficult to meet steam quantity requirements. The second type of scheme is simpler and more reliable, but its latent heat cannot be utilized due to the limitation imposed by the molten salt freezing point temperature, resulting in a relatively poor peak-shaving capacity. Summary of the Invention

[0005] To solve the above-mentioned technical problems, this invention provides a molten salt thermal energy storage method for energy cascade utilization. By utilizing the combined effects of molten salt storage tanks, water storage tanks, and electric heating, it achieves the purpose of high-efficiency energy storage, meets the peak shaving and frequency regulation requirements of different unit modes, and has good economic benefits.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows:

[0007] A molten salt thermal energy storage method for energy cascade utilization, which involves operating a thermal energy storage system in conjunction with different grid peak-shaving demands, and gradually activating the reheat section to the thermal energy storage system, the main steam to the thermal energy storage system, and the electric heater as the peak-shaving demand increases;

[0008] Including the following thermal storage operation modes:

[0009] S1. During the thermal storage period, when the power grid requires a lower peak shaving volume, the high-temperature steam pipeline valve from the reheat section to the second molten salt heater is opened, and the steam pipeline valve from the main steam to the first molten salt heater and the electric heater are closed. The second molten salt heater heats the molten salt from the cold salt tank and returns it to the hot salt tank. The high-temperature steam in the hot section becomes lower-temperature steam after passing through the second molten salt heater and enters the steam-water heat exchanger to heat the cold water from the cold water tank before returning it to the hot water tank. The low-temperature steam becomes high-temperature hot water after passing through the steam-water heat exchanger and is discharged to the deaerator.

[0010] S2. During the thermal storage period, as the power grid's demand for peak-shaving capacity increases, the high-temperature steam valves from the main steam to the first molten salt heater and from the reheat hot section to the second molten salt heater are opened simultaneously, while the electric heater is closed. After passing through the first molten salt heater, the main steam's parameters are reduced before it enters the reheat cold section steam pipeline. After passing through the second molten salt heater and the steam-water heat exchanger, the reheat hot section steam becomes high-temperature hot water and is discharged to the deaerator. Molten salt from the cold salt tank is discharged to the hot salt tank after passing through the first and second molten salt heaters, and cold water from the cold water tank is discharged to the hot water tank after passing through the steam-water heat exchanger.

[0011] S3. During the thermal storage period, as the grid further improves its peak-shaving capacity, the high-temperature steam valves from the main steam to the first molten salt heater, the reheat hot section to the second molten salt heater, and the electric heater are opened simultaneously. At this time, the unit's peak-shaving capacity reaches its maximum. After passing through the first molten salt heater, the main steam's parameters are reduced before it enters the reheat cold section steam pipeline. After passing through the second molten salt heater and the steam-water heat exchanger, the reheat hot section steam becomes high-temperature hot water and is discharged to the deaerator. Part of the molten salt from the cold salt tank is discharged to the hot salt tank after passing through the first and second molten salt heaters, and another part of the molten salt is heated by the electric heater and discharged to the hot salt tank. The cold water from the cold water tank is discharged to the hot water tank after passing through the steam-water heat exchanger.

[0012] S4. During the heat release period, the power grid makes demands on the unit's peak load. After the condensate pump is opened, the condensate pipeline valve to the preheater is opened. The low-temperature condensate absorbs heat from the water circulation loop in the preheater and its temperature rises. Due to the difference in the ratio of latent heat and sensible heat under different operating modes, the condensate is divided into two paths after the preheater. One path goes to the deaerator, and the other path absorbs heat from the molten salt circulation loop through the evaporator and superheater and becomes steam. After mixing with the high-temperature reheat steam, it enters the intermediate pressure cylinder of the turbine to do work.

[0013] A further improvement of the technical solution of the present invention is that: the heat storage system includes a first molten salt heater, a second molten salt heater, a steam-water heat exchanger and an electric heater in the heat storage circuit; a preheater, an evaporator and a superheater in the heat release circuit; a cold salt tank and a hot salt tank in the molten salt circulation circuit; and a cold water tank and a hot water tank in the water circulation circuit.

[0014] The steam inlet of the first molten salt heater in the heat storage circuit is connected to the original main steam outlet of the boiler via a high-temperature steam pipe F1, and the steam outlet of the first molten salt heater is connected to the original reheat cold section inlet of the boiler via a low-temperature steam pipe F2; the steam inlet of the second molten salt heater is connected to the original reheat hot section outlet of the boiler via a high-temperature steam pipe F1, and the steam outlet of the second molten salt heater is connected to the steam inlet of the steam-water heat exchanger via a low-temperature steam pipe F2; the hot water outlet of the steam-water heat exchanger is connected to the deaerator via a hot water pipe F3; the electric heater is connected to the generator outlet transformer.

[0015] In the heat release circuit, the original condensate is connected to the cold water inlet of the preheater through the cold water pipe F4. The hot water outlet of the preheater is divided into two paths: one path is connected to the deaerator through the hot water pipe F3, and the other path is connected to the hot water inlet of the evaporator through the hot water pipe F3. The steam outlet of the evaporator is connected to the steam inlet of the superheater through the steam pipe F0. The steam outlet of the superheater is mixed with the high-temperature reheat steam of the original reheat section through the high-temperature steam pipe F1 and then enters the intermediate pressure cylinder of the turbine to do work.

[0016] The outlet of the cold salt tank in the molten salt circulation loop is connected to the molten salt inlets of the first molten salt heater, the second molten salt heater, and the electric heater via a cold molten salt pipe F6. The molten salt outlets of the first molten salt heater, the second molten salt heater, and the electric heater are connected to the inlets of the hot salt tank. The outlet of the hot salt tank is connected to the molten salt inlet of the superheater via a molten salt pipe F7. The molten salt outlet of the superheater is connected to the molten salt inlet of the evaporator via a molten salt pipe F7. The molten salt outlet of the evaporator is connected to the inlet of the cold salt tank via a cold molten salt pipe F6.

[0017] The outlet of the cold water tank in the water circulation loop is connected to the cold water inlet of the steam-water heat exchanger via cold water pipe F4. The hot water outlet of the steam-water heat exchanger is connected to the inlet of the hot water tank via hot water pipe F3. The outlet of the hot water tank is connected to the hot water inlet of the preheater via hot water pipe F3. The cold water outlet of the preheater is connected to the inlet of the cold water tank via cold water pipe F4.

[0018] A further improvement of the technical solution of the present invention is that a cold salt pump is installed on the outlet pipe of the cold salt tank; and a hot salt pump is installed on the outlet pipe of the hot salt tank.

[0019] A further improvement of the technical solution of the present invention is that a cold water delivery pump is installed on the outlet pipe of the cold water tank; and a hot water delivery pump is installed on the outlet pipe of the hot water tank.

[0020] A further improvement of the technical solution of the present invention is that valves are provided on the steam pipe F0, high-temperature steam pipe F1, low-temperature steam pipe F2, hot water pipe F3, cold water pipe F4, hot molten salt pipe F5, cold molten salt pipe F6 and molten salt pipe F7.

[0021] A further improvement of the technical solution of the present invention is that: the valve from the preheater to the deaerator in mode S4 is interlocked with the valves in modes S1 to S3. According to different thermal storage operation modes, the valve opening from the preheater to the deaerator is adjusted to ensure that the flow rate to the deaerator and the flow rate to the evaporator are in a certain ratio, so as to control the parameter requirements of steam production and ensure the steam parameter requirements of the turbine.

[0022] The technological advancements achieved by this invention due to the adoption of the above technical solutions are as follows:

[0023] This invention utilizes the combined effects of molten salt storage tanks, water storage tanks, and electric heating to achieve efficient energy storage, meeting the peak shaving and frequency regulation needs of different unit modes, and offering good economic benefits.

[0024] This invention utilizes a thermal storage system that leverages energy cascades. By configuring different thermal storage devices according to varying peak-shaving needs of the power grid, it achieves flexible operation and maximizes the peak-shaving capacity of the generating units. The system is safe and reliable.

[0025] This invention features two pipelines and regulating valves after the preheater, enabling flexible control of steam parameters according to different operating modes and parameter requirements. It is also applicable to systems supplying industrial steam. Attached Figure Description

[0026] Figure 1 This is a system schematic diagram of the present invention;

[0027] Among them, 1. First molten salt heater, 2. Second molten salt heater, 3. Steam-water heat exchanger, 4. Electric heater, 5. Preheater, 6. Evaporator, 7. Superheater, 8. Cold salt tank, 9. Hot salt tank, 10. Cold water tank, 11. Hot water tank, 12. Cold salt pump, 13. Hot salt pump, 14. Cold water transfer pump, 15. Hot water transfer pump, 16. Boiler, 17. Deaerator, 18. Intermediate pressure cylinder of steam turbine, F0. Steam pipeline, F1. High temperature steam pipeline, F2. Low temperature steam pipeline, F3. Hot water pipeline, F4. Cold water pipeline, F5. Hot molten salt pipeline, F6. Cold molten salt pipeline, F7. Molten salt pipeline. Detailed Implementation

[0028] The present invention will be further described in detail below with reference to embodiments:

[0029] A molten salt thermal storage system utilizing energy cascades is configured with three different stages of media—main steam, reheat hot-section steam, and electric heaters—to heat molten salt for thermal storage. For example... Figure 1As shown, it includes a first molten salt heater 1, a second molten salt heater 2, a steam-water heat exchanger 3, and an electric heater 4 in the heat storage circuit; a preheater 5, an evaporator 6, and a superheater 7 in the heat release circuit; a cold salt tank 8 and a hot salt tank 9 in the molten salt circulation circuit; and a cold water tank 10 and a hot water tank 11 in the water circulation circuit.

[0030] The steam inlet of the first molten salt heater 1 in the heat storage circuit is connected to the original main steam outlet of the boiler 16 through a high-temperature steam pipe F1, and the steam outlet of the first molten salt heater 1 is connected to the original reheat cold section inlet of the boiler 16 through a low-temperature steam pipe F2; the steam inlet of the second molten salt heater 2 is connected to the original reheat hot section outlet of the boiler 16 through a high-temperature steam pipe F1, and the steam outlet of the second molten salt heater 2 is connected to the steam inlet of the steam-water heat exchanger 3 through a low-temperature steam pipe F2; the hot water outlet of the steam-water heat exchanger 3 is connected to the deaerator 17 through a hot water pipe F3; the electric heater 4 is connected to the generator outlet transformer.

[0031] In the heat release circuit, the original condensate is connected to the cold water inlet of the preheater 5 through the cold water pipe F4. The hot water outlet of the preheater 5 is divided into two paths: one path is connected to the deaerator 17 through the hot water pipe F3, and the other path is connected to the hot water inlet of the evaporator 6 through the hot water pipe F3. The steam outlet of the evaporator 6 is connected to the steam inlet of the superheater 7 through the steam pipe F0. The steam outlet of the superheater 7 is mixed with the high-temperature reheat steam of the original reheat section through the high-temperature steam pipe F1 and then enters the intermediate pressure cylinder 18 of the turbine to do work.

[0032] The outlet of the cold salt tank 8 in the molten salt circulation loop is connected to the molten salt inlets of the first molten salt heater 1, the second molten salt heater 2, and the electric heater 4 via a cold molten salt pipe F6, and a cold salt pump 12 is installed on the outlet pipe of the cold salt tank 8; the molten salt outlets of the first molten salt heater 1, the second molten salt heater 2, and the electric heater 4 are connected to the inlets of the hot salt tank 9, the outlet of the hot salt tank 9 is connected to the molten salt inlet of the superheater 7 via a molten salt pipe F7, and a hot salt pump 13 is installed on the outlet pipe of the hot salt tank 9; the molten salt outlet of the superheater 7 is connected to the molten salt inlet of the evaporator 6 via a molten salt pipe F7, and the molten salt outlet of the evaporator 6 is connected to the inlet of the cold salt tank 8 via a cold molten salt pipe F6;

[0033] The outlet of the cold water tank 10 in the water circulation loop is connected to the cold water inlet of the steam-water heat exchanger 3 via a cold water pipe F4, and a cold water delivery pump 14 is installed on the outlet pipe of the cold water tank 10. The hot water outlet of the steam-water heat exchanger 3 is connected to the inlet of the hot water tank 11 via a hot water pipe F3. The outlet of the hot water tank 11 is connected to the hot water inlet of the preheater 5 via a hot water pipe F3, and a hot water delivery pump 15 is installed on the outlet pipe of the hot water tank 11. The cold water outlet of the preheater 5 is connected to the inlet of the cold water tank 10 via a cold water pipe F4.

[0034] Valves are installed on the steam pipe F0, high-temperature steam pipe F1, low-temperature steam pipe F2, hot water pipe F3, cold water pipe F4, hot molten salt pipe F5, cold molten salt pipe F6, and molten salt pipe F7 to regulate the flow rate.

[0035] A molten salt thermal energy storage method for energy cascade utilization, which involves operating a thermal energy storage system in conjunction with different grid peak-shaving demands, and gradually activating the reheat section to the thermal energy storage system, the main steam to the thermal energy storage system, and the electric heater as peak-shaving demand increases; including the following thermal energy storage operation modes:

[0036] S1. During the heat storage period, when the power grid requires a lower peak shaving amount, the high-temperature steam pipeline valve from the reheat section to the second molten salt heater 2 is opened, and the steam pipeline valve from the main steam to the first molten salt heater 1 and the electric heater 4 are closed. The second molten salt heater 2 heats the molten salt from the cold salt tank 8 and returns it to the hot salt tank 9. The high-temperature steam in the hot section becomes lower-temperature steam after passing through the second molten salt heater 2, enters the steam-water heat exchanger 3, heats the cold water from the cold water tank 10, and then returns it to the hot water tank 11. The low-temperature steam becomes high-temperature hot water after passing through the steam-water heat exchanger 3 and is discharged to the deaerator.

[0037] S2. During the thermal storage period, as the power grid's demand for peak-shaving capacity increases, the high-temperature steam valves from the main steam to the first molten salt heater 1 and from the reheat hot section to the second molten salt heater 2 are opened simultaneously, while the electric heater 4 is closed. After passing through the first molten salt heater 1, the main steam's parameters are reduced, and it enters the reheat cold section steam pipeline. After passing through the second molten salt heater 2 and the steam-water heat exchanger 3, the reheat hot section steam becomes high-temperature hot water and is discharged to the deaerator 17. Molten salt from the cold salt tank 8 is discharged to the hot salt tank 9 after passing through the first molten salt heater 1 and the second molten salt heater 2, and cold water from the cold water tank 10 is discharged to the hot water tank 11 after passing through the steam-water heat exchanger 3.

[0038] S3. During the thermal storage period, as the grid further improves its peak-shaving capacity, the high-temperature steam valves from the main steam to the first molten salt heater 1, from the reheat hot section to the second molten salt heater 2, and the electric heater 4 are opened simultaneously. At this time, the unit's peak-shaving capacity reaches its maximum. After passing through the first molten salt heater 1, the main steam's parameters are reduced and it enters the reheat cold section steam pipeline. After passing through the second molten salt heater 2 and the steam-water heat exchanger 3, the reheat hot section steam becomes high-temperature hot water and is discharged to the deaerator 17. Part of the molten salt from the cold salt tank 8 is discharged to the hot salt tank 9 after passing through the first molten salt heater 1 and the second molten salt heater 2, and another part of the molten salt is heated by the electric heater 4 and discharged to the hot salt tank 9. The cold water from the cold water tank 10 is discharged to the hot water tank 11 after passing through the steam-water heat exchanger 3.

[0039] S4. During the heat release period, the power grid makes demands on the unit's peak load. After the condensate pump is turned on, the condensate pipeline valve to the preheater 5 is opened. The low-temperature condensate absorbs heat from the water circulation loop in the preheater 5 and its temperature rises. Due to the difference in the ratio of latent heat and sensible heat under different operating modes, the preheater 5 is divided into two paths. One path goes to the deaerator 17, and the other path absorbs heat from the molten salt circulation loop through the evaporator 6 and superheater 7 and becomes steam. After mixing with the high-temperature reheat steam, it enters the intermediate pressure cylinder of the turbine to do work.

[0040] In mode S4, the valves from preheater 5 to deaerator 17 are interlocked with those in modes S1 to S3. Depending on the different thermal storage operation modes, the valve openings from preheater to deaerator are adjusted to ensure that the flow rate to deaerator and the flow rate to evaporator are in a certain ratio, so as to control the steam output parameter requirements and ensure the steam parameter requirements to the turbine.

Claims

1. A molten salt thermal storage method for energy cascade utilization, characterized in that: According to different power grid peak-shaving needs, a thermal storage system is operated in conjunction with it. As the peak-shaving demand increases, the reheat section to the thermal storage system, the main steam to the thermal storage system, and the electric heater are gradually activated. The thermal storage system includes a first molten salt heater (1), a second molten salt heater (2), a steam-water heat exchanger (3), and an electric heater (4) in the thermal storage circuit; a preheater (5), an evaporator (6), and a superheater (7) in the heat release circuit; a cold salt tank (8) and a hot salt tank (9) in the molten salt circulation circuit; and a cold water tank (10) and a hot water tank (11) in the water circulation circuit. The steam inlet of the first molten salt heater (1) in the heat storage circuit is connected to the original main steam outlet of the boiler (16) through a high-temperature steam pipe F1, and the steam outlet of the first molten salt heater (1) is connected to the original reheat cold section inlet of the boiler (16) through a low-temperature steam pipe F2; the steam inlet of the second molten salt heater (2) is connected to the original reheat hot section outlet of the boiler (16) through a high-temperature steam pipe F1, and the steam outlet of the second molten salt heater (2) is connected to the steam inlet of the steam-water heat exchanger (3) through a low-temperature steam pipe F2, and the hot water outlet of the steam-water heat exchanger (3) is connected to the deaerator (17) through a hot water pipe F3; the electric heater (4) is connected to the generator outlet transformer; In the heat release circuit, the original condensate is connected to the cold water inlet of the preheater (5) through the cold water pipe F4. The hot water outlet of the preheater (5) is divided into two paths: one path is connected to the deaerator (17) through the hot water pipe F3, and the other path is connected to the hot water inlet of the evaporator (6) through the hot water pipe F3. The steam outlet of the evaporator (6) is connected to the steam inlet of the superheater (7) through the steam pipe F0. The steam outlet of the superheater (7) is mixed with the high temperature reheat steam of the original reheat section through the high temperature steam pipe F1 and then enters the intermediate pressure cylinder (18) of the turbine to do work. The outlet of the cold salt tank (8) of the molten salt circulation loop is connected to the molten salt inlets of the first molten salt heater (1), the second molten salt heater (2) and the electric heater (4) respectively through the cold molten salt pipe F6; the molten salt outlets of the first molten salt heater (1), the second molten salt heater (2) and the electric heater (4) are connected to the inlet of the hot salt tank (9) respectively; the outlet of the hot salt tank (9) is connected to the molten salt inlet of the superheater (7) through the molten salt pipe F7; the molten salt outlet of the superheater (7) is connected to the molten salt inlet of the evaporator (6) through the molten salt pipe F7; and the molten salt outlet of the evaporator (6) is connected to the inlet of the cold salt tank (8) through the cold molten salt pipe F6. The outlet of the cold water tank (10) of the water circulation loop is connected to the cold water inlet of the steam-water heat exchanger (3) through the cold water pipe F4. The hot water outlet of the steam-water heat exchanger (3) is connected to the inlet of the hot water tank (11) through the hot water pipe F3. The outlet of the hot water tank (11) is connected to the hot water inlet of the preheater (5) through the hot water pipe F3. The cold water outlet of the preheater (5) is connected to the inlet of the cold water tank (10) through the cold water pipe F4. Including the following thermal storage operation modes: S1. During the heat storage period, under the condition that the power grid requires a low peak shaving amount, the high temperature steam pipeline valve from the reheat section to the second molten salt heater (2) is opened, and the steam pipeline valve from the main steam to the first molten salt heater (1) and the electric heater (4) are closed. The second molten salt heater (2) heats the molten salt from the cold salt tank (8) and returns it to the hot salt tank (9). The high temperature steam in the hot section becomes lower temperature steam after passing through the second molten salt heater (2) and enters the steam-water heat exchanger (3) to heat the cold water from the cold water tank (10) and then returns it to the hot water tank (11). The low temperature steam becomes high temperature hot water after passing through the steam-water heat exchanger (3) and is discharged to the deaerator. S2. During the heat storage period, as the power grid increases its peak-shaving capacity requirements, the high-temperature steam valves from the main steam to the first molten salt heater (1) and from the reheat hot section to the second molten salt heater (2) are opened, and the electric heater (4) is closed. After the main steam passes through the first molten salt heater (1), the parameters are reduced and it enters the reheat cold section steam pipeline. After the reheat hot section steam passes through the second molten salt heater (2) and the steam-water heat exchanger (3), it becomes high-temperature hot water and is discharged to the deaerator (17). Molten salt from the cold salt tank (8) is discharged to the hot salt tank (9) after passing through the first molten salt heater (1) and the second molten salt heater (2). Cold water from the cold water tank (10) is discharged to the hot water tank (11) after passing through the steam-water heat exchanger (3). S3. During the heat storage period, as the power grid further improves its peak-shaving capacity, the high-temperature steam valves from the main steam to the first molten salt heater (1), the reheat hot section to the second molten salt heater (2), and the electric heater (4) are opened simultaneously. At this time, the unit's peak-shaving capacity reaches its maximum. After the main steam passes through the first molten salt heater (1), the parameters are reduced and it enters the reheat cold section steam pipeline. After the reheat hot section steam passes through the second molten salt heater (2) and the steam-water heat exchanger (3), it becomes high-temperature hot water and is discharged to the deaerator (17). Part of the molten salt from the cold salt tank (8) is discharged to the hot salt tank (9) after passing through the first molten salt heater (1) and the second molten salt heater (2). Another part of the molten salt is heated by the electric heater (4) and discharged to the hot salt tank (9). The cold water from the cold water tank (10) is discharged to the hot water tank (11) after passing through the steam-water heat exchanger (3). S4. During the heat release period, the power grid makes a demand on the peak of the unit; after the condensate pump is turned on, the condensate pipeline valve to the preheater (5) is opened, and the temperature of the low temperature condensate rises after absorbing the heat of the water circulation loop through the preheater (5); due to the difference in the ratio of latent heat and sensible heat under different operating modes, the preheater (5) is divided into two paths, one to the deaerator (17), and the other to the evaporator (6) and the superheater (7) to absorb the heat of the molten salt circulation loop and become steam. After mixing with the high temperature reheat steam, it enters the intermediate pressure cylinder of the steam turbine to do work.

2. The molten salt thermal storage method for energy cascade utilization according to claim 1, characterized in that: A cold salt pump (12) is installed on the outlet pipe of the cold salt tank (8); a hot salt pump (13) is installed on the outlet pipe of the hot salt tank (9).

3. The molten salt thermal storage method for energy cascade utilization according to claim 1, characterized in that: A cold water delivery pump (14) is installed on the outlet pipe of the cold water tank (10); a hot water delivery pump (15) is installed on the outlet pipe of the hot water tank (11).

4. The molten salt thermal storage method for energy cascade utilization according to claim 1, characterized in that: Valves are installed on the steam pipe F0, high-temperature steam pipe F1, low-temperature steam pipe F2, hot water pipe F3, cold water pipe F4, hot molten salt pipe F5, cold molten salt pipe F6, and molten salt pipe F7.

5. A molten salt thermal storage method for energy cascade utilization according to claim 4, characterized in that: In mode S4, the valves from the preheater (5) to the deaerator (17) are interlocked with those in modes S1 to S3. The valve openings from the preheater to the deaerator are adjusted according to different thermal storage operation modes to ensure that the flow rate to the deaerator and the flow rate to the evaporator are in a certain ratio, so as to control the parameters required for steam production and ensure the steam parameters required for the turbine.

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