A system and method for hierarchical molten salt heat storage coupled with a thermal power unit under a power market

Abstract

This invention relates to a system and method for a graded molten salt thermal storage coupled cogeneration unit under an electricity market, comprising a boiler, a first generator set, a circulating water circuit, a main steam molten salt thermal storage and release subsystem, a heating steam molten salt thermal storage and release subsystem, a second generator set, industrial steam users, heating users, and a control subsystem. The boiler's steam outlet is connected to the steam inlet of the first generator set and the steam inlet of the main steam molten salt thermal storage and release subsystem. The heat storage end steam outlet and the heat release end steam outlet of the main steam molten salt thermal storage and release subsystem are connected to the industrial steam user and the heating user, respectively. The heat storage end steam inlet of the heating steam molten salt thermal storage and release subsystem is connected to the heat storage end steam outlet and the heat release end steam outlet of the main steam molten salt thermal storage and release subsystem, respectively. This invention enables the unit to reduce losses and utilize molten salt steam heat during periods of negative electricity prices, and to cut off heating and heating loads during periods of positive electricity prices, thereby improving the unit's operational economy.

Description

Technical Field

[0001] This invention relates to the field of molten salt thermal energy storage technology, and in particular to a system and method for a graded molten salt thermal energy storage coupled to a thermal power unit in an electricity market. Background Technology

[0002] In recent years, with the rapid development of new energy sources, the stable operation of the power grid has been affected by the intermittent nature of new energy power generation. Coal-fired power generation units, however, have consistently demonstrated good stability and excellent peak-shaving capabilities, effectively mitigating the instability brought to the power grid by new energy sources. Therefore, coal-fired power units will continue to occupy an important position in the power system. In northern my country, a considerable number of coal-fired power units are responsible for industrial and residential heating. These combined heat and power (CHP) units have relatively small capacities, and during heating seasons, they also need to supply steam, which limits their peak-shaving range. Furthermore, under the current electricity spot market, there are periods of negative electricity prices every day, severely reducing the economic viability of these units.

[0003] Based on my country's current energy policy and development trends, installing hot water storage tanks, electric thermal storage boilers, and coupled molten salt thermal storage systems on the heating network side are common measures for flexible retrofitting of thermal power units to achieve thermal-electric decoupling. The working principle of hot water storage tanks on the heating network side is that during peak daytime load periods, additional steam is extracted to heat a portion of the heating network circulating water and store it in the tanks. During off-peak nighttime load periods, the hot water stored in the tanks is directly supplied for heating, allowing the unit to achieve deeper peak shaving. Electric thermal storage boilers work similarly to hot water storage tanks, utilizing off-peak nighttime load periods to generate additional electricity to heat and store hot water, which is then used during peak daytime load periods. Direct hot water supply can increase the output of the generating unit; however, these two methods have the following disadvantages: 1. The degree of peak shaving and valley filling is limited; 2. System equipment is shut down during the non-heating season; 3. Compared with molten salt, water has a very narrow heat storage range. Therefore, coupling a molten salt thermal storage system with a cogeneration unit is one of the best methods for flexible retrofitting of cogeneration units. Molten salt thermal storage has been applied to many solar thermal power generation projects at home and abroad, and the technology is mature. However, considering the characteristics of peak and valley electricity prices and the working characteristics of cogeneration units, how to efficiently and scientifically couple a molten salt thermal storage system, combined with intraday electricity prices to obtain ideal returns, and a scientific and reasonable operation strategy are issues worthy of research and consideration. Summary of the Invention

[0004] This invention provides a system and method for a graded molten salt thermal storage coupled cogeneration unit in the electricity market. This system enables the unit to reduce losses and utilize the heat of molten salt steam during periods of negative electricity price, and to cut off the heating and heating burden during periods of positive electricity price, thereby increasing profits through centralized power generation. Furthermore, it utilizes the heat released by molten salt to increase the electrical load and improve the operating economy of the unit.

[0005] To achieve the above objectives, the present invention adopts the following technical solution:

[0006] A system for a graded molten salt thermal storage coupled cogeneration unit under the electricity market includes a boiler, a first generator set, a circulating water circuit, a main steam molten salt thermal storage and release subsystem, a heating steam molten salt thermal storage and release subsystem, a second generator set, industrial steam users, heating users, and a control subsystem.

[0007] The steam outlet of the aforementioned boiler is connected to the steam inlet of the aforementioned first generator set and the steam inlet of the aforementioned main steam molten salt heat storage and release subsystem, respectively. The heat storage end steam outlet and the heat release end steam outlet of the aforementioned main steam molten salt heat storage and release subsystem are connected to the aforementioned industrial steam user and heating user, respectively.

[0008] The heat storage end steam inlet of the above-mentioned heating steam molten salt heat storage and release subsystem is connected to the heat storage end steam outlet and the heat release end steam outlet of the above-mentioned main steam molten salt heat storage and release subsystem, respectively. The heat release end steam outlet of the above-mentioned heating steam molten salt heat storage and release subsystem is connected to the steam inlet of the above-mentioned second generator set.

[0009] The aforementioned circulating water circuits are respectively connected to the aforementioned boiler, the aforementioned first generator set, the aforementioned main steam molten salt heat storage and release subsystem, and the aforementioned heating steam molten salt heat storage and release subsystem to provide circulating water;

[0010] During periods of negative electricity prices, the aforementioned control subsystem controls the connection between the steam outlet of the boiler and the steam inlet of the main steam molten salt storage and release subsystem, and the connection between the steam outlet of the heat storage end of the main steam molten salt storage and release subsystem and the industrial steam user. During winter periods, the control subsystem controls the connection between the steam outlet of the heat storage end of the main steam molten salt storage and release subsystem and the heating user. During non-winter periods, the control subsystem controls the connection between the steam outlet of the heat storage end of the main steam molten salt storage and release subsystem and the steam inlet of the heat storage end of the heating steam molten salt storage and release subsystem.

[0011] During periods of positive electricity prices, the aforementioned control subsystem controls the connection between the steam outlet of the boiler and the steam inlet of the first generator set, the connection between the heat release outlet of the main steam molten salt storage and release subsystem and the industrial steam user, and the connection between the heat release outlet of the heating steam molten salt storage and release subsystem and the steam inlet of the second generator set. During winter periods, the control subsystem controls the connection between the heat release outlet of the main steam molten salt storage and release subsystem and the heating user, or during non-winter periods, the control subsystem controls the connection between the heat release outlet of the main steam molten salt storage and release subsystem and the heat storage inlet of the heating steam molten salt storage and release subsystem.

[0012] Preferably, the main steam molten salt heat storage and release subsystem includes a main steam molten salt heat exchanger, a high-temperature molten salt hot storage tank, a high-temperature molten salt pump, a high-temperature molten salt condensate heat exchanger, a high-temperature molten salt cold storage tank, and a first low-temperature molten salt pump connected in sequence. The first low-temperature molten salt pump is connected to the molten salt inlet of the main steam molten salt heat exchanger. The steam outlet of the boiler is connected to the steam inlet of the main steam molten salt heat exchanger. The steam outlet of the main steam molten salt heat exchanger is connected to the industrial steam user and the heating user. The circulating water circuit is connected to the water inlet of the high-temperature molten salt condensate heat exchanger. The steam outlet of the high-temperature molten salt condensate heat exchanger is connected to the industrial steam user and the heating user.

[0013] Preferably, the heating steam molten salt heat storage and release subsystem includes a heating steam molten salt heat exchanger, a medium-temperature molten salt heat storage tank, a medium-temperature molten salt pump, a medium-temperature molten salt condensate heat exchanger, a medium-temperature molten salt cold storage tank, and a second low-temperature molten salt pump connected in sequence. The second low-temperature molten salt pump is connected to the molten salt inlet of the heating steam molten salt heat exchanger. The steam outlet of the high-temperature molten salt condensate heat exchanger is connected to the steam inlet of the heating steam molten salt heat exchanger. The water outlet of the heating steam molten salt heat exchanger is connected to the circulating water circuit. The circulating water circuit, the medium-temperature molten salt condensate heat exchanger, and the second generator set are connected in sequence.

[0014] Preferably, the circulating water circuit includes a water supply pipe, a condenser, a condensate pump, a low-pressure heater, a deaerator, and a high-pressure heater connected in sequence. The inlet of the condenser is connected to the steam outlet of the first generator set, and the outlet of the high-pressure heater is connected to the inlet of the boiler.

[0015] Preferably, the heat storage end steam outlet of the main steam molten salt heat storage and release subsystem is connected to the steam inlet of the deaerator.

[0016] Preferably, the first generator set includes a high-pressure cylinder, an intermediate-pressure cylinder, a low-pressure cylinder, and a first generator arranged coaxially. The steam inlets of the high-pressure cylinder and the intermediate-pressure cylinder are respectively connected to the steam outlet of the boiler. The steam outlet of the intermediate-pressure cylinder is connected to the steam inlet of the low-pressure cylinder. The steam outlet of the low-pressure cylinder is connected to the steam inlet of the low-pressure heater. The steam outlet of the intermediate-pressure cylinder is connected to the steam inlet of the deaerator. The steam outlet of the high-pressure cylinder is connected to the steam inlet of the high-pressure heater.

[0017] A method for a staged molten salt thermal storage coupled cogeneration unit system in an electricity market includes the following steps:

[0018] During periods of negative electricity prices, the first generator set and the second generator set are not in operation. The boiler supplies steam to the main steam molten salt heat storage and release subsystem. The main steam exchanges heat with the heat storage end of the main steam molten salt heat storage and release subsystem. The circulating water circuit supplies water to the boiler.

[0019] If it is winter, the steam after heat exchange will enter the aforementioned industrial steam users and heating users.

[0020] If it is not winter, part of the steam after heat exchange will enter the industrial steam user, and the other part will exchange heat with the heat storage end of the main steam molten salt heat storage and release subsystem. The molten salt will store the heat of the steam.

[0021] During periods of positive electricity prices, the first generator set and the second generator set operate separately. All the steam in the boiler enters the first generator set to generate electricity. The circulating water circuit supplies water to the boiler. The heat release end of the main steam molten salt storage and release subsystem releases molten salt heat and exchanges heat with the circulating water to generate steam. All the steam in the second generator set generates electricity. The heat release end of the main steam molten salt storage and release subsystem releases molten salt heat and exchanges heat with the circulating water to generate steam.

[0022] During winter, all the steam generated at the heat release end of the main steam molten salt storage and heat release subsystem enters the industrial steam users and heating users.

[0023] During non-winter periods, part of the steam generated at the heat release end of the main steam molten salt storage and release subsystem enters the industrial steam user, while the other part exchanges molten salt heat with the heat stored in the main steam molten salt storage and release subsystem, and the resulting water enters the circulating water circuit.

[0024] Preferably, the main steam molten salt heat storage and release subsystem includes a main steam molten salt heat exchanger, a high-temperature molten salt hot storage tank, a high-temperature molten salt pump, a high-temperature molten salt condensate heat exchanger, a high-temperature molten salt cold storage tank, and a first low-temperature molten salt pump; the heating steam molten salt heat storage and release subsystem includes a heating steam molten salt heat exchanger, a medium-temperature molten salt hot storage tank, a medium-temperature molten salt pump, a medium-temperature molten salt condensate heat exchanger, a medium-temperature molten salt cold storage tank, and a second low-temperature molten salt pump connected in sequence.

[0025] During the winter period of negative electricity prices, all the steam in the above-mentioned boiler enters the above-mentioned main steam molten salt heat exchanger. At the same time, the above-mentioned first low-temperature molten salt pump is running and the above-mentioned high-temperature molten salt pump is not running. The molten salt in the above-mentioned high-temperature molten salt cold storage tank is pumped into the above-mentioned main steam molten salt heat exchanger to exchange heat with the high-temperature steam, and then enters the above-mentioned high-temperature molten salt hot storage tank for storage.

[0026] During the winter season, the steam that has undergone heat exchange in the aforementioned main steam molten salt heat exchanger enters the aforementioned industrial steam users and the aforementioned heating users.

[0027] During non-winter periods, after the steam has been heated by the main steam molten salt heat exchanger, part of it enters the industrial steam user and the other part enters the heating steam molten salt heat exchanger. At the same time, the second low-temperature molten salt pump is running while the medium-temperature molten salt pump is not running. Molten salt in the medium-temperature molten salt cold storage tank is pumped into the heating steam molten salt heat exchanger to exchange heat with the steam, and then stored in the medium-temperature molten salt hot storage tank.

[0028] Preferably, the main steam molten salt heat storage and release subsystem includes a main steam molten salt heat exchanger, a high-temperature molten salt hot storage tank, a high-temperature molten salt pump, a high-temperature molten salt condensate heat exchanger, a high-temperature molten salt cold storage tank, and a first low-temperature molten salt pump; the heating steam molten salt heat storage and release subsystem includes a heating steam molten salt heat exchanger, a medium-temperature molten salt hot storage tank, a medium-temperature molten salt pump, a medium-temperature molten salt condensate heat exchanger, a medium-temperature molten salt cold storage tank, and a second low-temperature molten salt pump connected in sequence.

[0029] During periods of positive electricity prices, both the first and second generator sets operate. All the steam in the boiler enters the first generator set for power generation. Simultaneously, the medium-temperature molten salt pump operates while the second low-temperature molten salt pump does not. Molten salt in the medium-temperature molten salt heat storage tank enters the medium-temperature molten salt condensate heat exchanger through the medium-temperature molten salt pump and exchanges heat with the circulating water to generate steam. The generated steam enters the second generator set for power generation. At the same time, the high-temperature molten salt pump operates while the first low-temperature molten salt pump does not. Molten salt in the high-temperature molten salt heat storage tank enters the high-temperature molten salt condensate heat exchanger through the high-temperature molten salt pump and exchanges heat with the circulating water to generate steam.

[0030] During the winter season, all the steam generated by the aforementioned high-temperature molten salt condensate heat exchanger is delivered to the aforementioned industrial steam users and heating users.

[0031] During non-winter periods, part of the steam generated by the high-temperature molten salt condensate heat exchanger enters the industrial steam user and the other part enters the heating steam molten salt heat exchanger. At the same time, the molten salt in the medium-temperature molten salt cold storage tank enters the heating steam molten salt heat exchanger through the second low-temperature molten salt pump and exchanges heat with the steam, and then enters the medium-temperature molten salt hot storage tank for storage.

[0032] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0033] During the winter months with negative electricity prices, power generation is stopped, and all boiler steam is used for heating and molten salt heat storage in the main steam molten salt heat storage subsystem, thereby reducing unit load and minimizing losses. During the non-winter months with negative electricity prices, a portion of the steam is used for heating, while the remaining steam is stored in the molten salt of the heating steam molten salt heat storage subsystem, reducing energy loss and minimizing losses. During the winter months with positive electricity prices, heating is achieved through the molten salt heat release of the main steam molten salt heat storage subsystem. During the non-winter months with positive electricity prices, a portion of the steam heated by the molten salt heat release of the main steam molten salt heat storage subsystem is used for heating. The heating steam molten salt heat storage subsystem stores the steam heat again in the molten salt, thereby reducing heat loss. During periods of positive electricity price, the first generator unit uses boiler steam to generate electricity, while the second generator unit uses the heat stored during periods of negative electricity price to generate electricity, increasing the output load and generating more profit through centralized power generation. Thus, under the peak-valley electricity price policy, compared with setting up hot water storage tanks and electric thermal storage boilers on the heating network side, it greatly realizes peak shaving and valley filling and decoupling of heat and electricity during peak electricity periods, improving the operating economy of the unit and increasing the unit's power generation revenue. Attached Figure Description

[0034] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0035] Figure 1 This is an overall block diagram of an embodiment of the present invention;

[0036] Figure 2 This is a block diagram illustrating the system operation during the winter period with negative electricity prices, as described in an embodiment of the present invention.

[0037] Figure 3 This is a block diagram illustrating the system operation during non-winter periods with negative electricity prices in an embodiment of the present invention.

[0038] Figure 4 This is a block diagram illustrating the system operation during the winter period with positive electricity prices, as described in an embodiment of the present invention.

[0039] Figure 5 This is a block diagram of system operation during non-winter periods with positive electricity prices in the embodiment of the present invention (the dashed lines in the above operation block diagram represent the non-operation state).

[0040] Explanation of reference numerals in the attached figures:

[0041] 1. Boiler; 2. First Generator Set; 21. High-Pressure Cylinder; 22. Intermediate-Pressure Cylinder; 23. Low-Pressure Cylinder; 24. First Generator; 3. Circulating Water Circuit; 31. Condenser; 32. Condensate Pump; 33. Low-Pressure Heater; 34. Deaerator; 35. High-Pressure Heater; 4. Makeup Water Pipe; 5. Main Steam Molten Salt Heat Storage and Release Subsystem; 51. Main Steam Molten Salt Heat Exchanger; 52. High-Temperature Molten Salt Heat Storage Tank; 53. High-Temperature Molten Salt Pump; 54. High-Temperature Molten Salt Condensate Heat Exchanger; 55. High-Temperature Molten Salt Cold Storage Tank; 56. First Low-Temperature Molten Salt Pump; 6. Heating Steam Molten Salt Heat Storage and Release Subsystem; 61. Heating Steam Molten Salt Heat Exchanger 62. Medium-temperature molten salt heat storage tank; 63. Medium-temperature molten salt pump; 64. Medium-temperature molten salt condensate heat exchanger; 65. Medium-temperature molten salt cold storage tank; 66. Second low-temperature molten salt pump; 7. Second generator set; 71. Second steam turbine; 72. Second generator; 8. Industrial steam user; 9. Heating user; 10. First pipeline; 11. Second pipeline; 12. Third pipeline; 13. Fourth pipeline; 14. Fifth pipeline; 15. Sixth pipeline; 16. Seventh pipeline; 17. Eighth pipeline; 18. Ninth pipeline; 19. Tenth pipeline; 200. First steam supply pipeline; 201. Second steam supply pipeline. Detailed Implementation

[0042] The technical solution of the present invention will now be clearly and completely described with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0043] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0044] In the description of this invention, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0045] This invention provides a system for graded molten salt thermal storage coupled with a cogeneration unit in an electricity market, such as... Figure 1 As shown, the system includes a boiler 1, a first generator set 2, a circulating water system 3, a main steam molten salt heat storage and release subsystem 5, a heating steam molten salt heat storage and release subsystem 6, a second generator set 7, an industrial steam user 8, a heating user 9, and a control subsystem. The steam outlet of the boiler 1 is connected to the steam inlet of the first generator set 2 and the steam inlet of the main steam molten salt heat storage and release subsystem 5. The heat storage end steam outlet and the heat release end steam outlet of the main steam molten salt heat storage and release subsystem 5 are connected to the industrial steam user 8 and the heating user 9, respectively. The heat storage end steam inlet of the heating steam molten salt heat storage and release subsystem 6 is connected to the heat storage end steam outlet and the heat release end steam outlet of the main steam molten salt heat storage and release subsystem 5. The heat release end steam outlet of the heating steam molten salt heat storage and release subsystem 6 is connected to the steam inlet of the second generator set 7. The circulating water system 3 is connected to the boiler 1, the first generator set 2, the main steam molten salt heat storage and release subsystem 5, and the heating steam molten salt heat storage and release subsystem 6 to provide circulating water.

[0046] During periods of negative electricity prices, the control subsystem connects the steam outlet of boiler 1 to the steam inlet of the main steam molten salt heat storage and release subsystem 5. This allows all the steam in boiler 1 to enter the main steam molten salt heat storage and release subsystem 5 and exchange heat with the molten salt. The portion of the steam heat used for the first generator unit 2 is stored for future use, thereby reducing the unit load and minimizing losses. The steam outlet at the heat storage end of the main steam molten salt heat storage and release subsystem 5 is connected to industrial steam user 8 for heating. During winter periods, the control subsystem connects the steam outlet at the heat storage end of the main steam molten salt heat storage and release subsystem 5 to heating user 9 for heating. Alternatively, during non-winter periods, the control subsystem connects the steam outlet at the heat storage end of the main steam molten salt heat storage and release subsystem 5 to the steam inlet at the heat storage end of the heating steam molten salt heat storage and release subsystem 6. Since the heating user is not operating, this portion of heat is stored to prevent heat loss.

[0047] During periods of positive electricity prices, the control subsystem connects the steam outlet of boiler 1 to the steam inlet of the first generator set 2, so that all the steam in boiler 1 is used for power generation, resulting in centralized power generation and increased revenue. The steam outlet of the main steam molten salt storage and release subsystem 5 is connected to the industrial steam user 8 for heating. The steam outlet of the heating steam molten salt storage and release subsystem 6 is connected to the steam inlet of the second generator set 7, increasing the electrical load and revenue. During winter, the control subsystem connects the steam outlet of the main steam molten salt storage and release subsystem 5 to the heating user 9 for heating. Alternatively, during non-winter periods, the control subsystem connects the steam outlet of the main steam molten salt storage and release subsystem 5 to the steam inlet of the heating steam molten salt storage and release subsystem 6, so that the heating user is not operating and the heat is stored to avoid heat loss.

[0048] By controlling the subsystem to operate different loops during different electricity price periods, peak shaving and valley filling and thermal-electric decoupling during peak electricity periods are largely achieved, improving the unit's operating economy and increasing the unit's power generation revenue.

[0049] Specifically, the first generator set 2 includes a high-pressure cylinder 21, an intermediate-pressure cylinder 22, a low-pressure cylinder 23, and a first generator 24, all coaxially arranged. The steam inlets of the high-pressure cylinder 21 and the intermediate-pressure cylinder are respectively connected to the steam outlet of the boiler 1, and the steam outlet of the intermediate-pressure cylinder 22 is connected to the steam inlet of the low-pressure cylinder 23. The circulating water circuit 3 includes a water supply pipe 4, a condenser 31, a condensate pump 32, a low-pressure heater 33, a deaerator 34, and a high-pressure heater 35 connected in sequence. The water inlet of the condenser 31 is connected to the steam outlet of the low-pressure cylinder 23, and the steam outlet of the high-pressure heater 34 is connected to the steam outlet of the deaerator 35. The water outlet is connected to the water inlet of boiler 1, the steam outlet of low-pressure cylinder 23 is connected to the steam inlet of low-pressure heater 33, the steam outlet of intermediate-pressure cylinder 22 is connected to the steam inlet of deaerator 34, and the steam outlet of high-pressure cylinder 21 is connected to the steam inlet of high-pressure heater 35. A first pipe 10 connects condensate pump 32 and low-pressure heater 33, and a water supply pipe 4 connects the water inlet of condenser 31. The second generator set 7 includes a second steam turbine 71 and a second generator 72, with the second steam turbine 71 driving the second generator 72 to generate electricity.

[0050] Specifically, the main steam molten salt heat storage and release subsystem 5 includes, in sequence, a main steam molten salt heat exchanger 51, a high-temperature molten salt heat storage tank 52, a high-temperature molten salt pump 53, a high-temperature molten salt condensate heat exchanger 54, a high-temperature molten salt cold storage tank 55, and a first low-temperature molten salt pump 56. The first low-temperature molten salt pump 56 is connected to the molten salt inlet of the main steam molten salt heat exchanger 51. The steam outlet of the boiler 1 is connected to the steam inlet of the main steam molten salt heat exchanger 51. The steam outlet of the main steam molten salt heat exchanger 51 is connected to the industrial steam user 8 and the heating user 9. The outlet of the condensate pump 32 is connected to the inlet of the high-temperature molten salt condensate heat exchanger 54. The steam outlet of the high-temperature molten salt condensate heat exchanger 54 is connected to the industrial steam user 8 and the heating user 9. Specifically, a first steam supply pipeline 200 connects the steam outlet of the boiler 1 and the steam inlet of the main steam molten salt heat exchanger 51. The outlet of the condensate pump 32... A second pipe 11 connects to the inlet of the high-temperature molten salt condensate heat exchanger 54. A third pipe 12 connects to the outlet of the high-temperature molten salt condensate heat exchanger 54. A fourth pipe 13 connects the outlet of the third pipe 12 to the industrial steam user 8. A fifth pipe 14 connects the outlet of the third pipe 12 to the heating user 9. A sixth pipe 15 connects to the outlet of the main steam molten salt heat exchanger 51. A seventh pipe 16 connects the sixth pipe 15 and the third pipe 12. An eighth pipe 17 connects the sixth pipe 15 to the inlet of the deaerator 34. During periods of negative electricity prices, by opening the first steam supply pipe 200, all the steam from the boiler 1 can enter the main steam molten salt heat exchanger 51 for molten salt heat storage. Then, by opening the sixth pipe 15, the seventh pipe 16, and the eighth pipe 17, steam heating can be achieved.

[0051] Specifically, the heating steam molten salt heat storage and release subsystem 6 includes, in sequence, a heating steam molten salt heat exchanger 61, a medium-temperature molten salt hot storage tank 62, a medium-temperature molten salt pump 63, a medium-temperature molten salt condensate heat exchanger 64, a medium-temperature molten salt cold storage tank 65, and a second low-temperature molten salt pump 66. The second low-temperature molten salt pump 66 is connected to the molten salt inlet of the heating steam molten salt heat exchanger 61, and the steam outlet of the high-temperature molten salt condensate heat exchanger 54 is connected to the steam inlet of the heating steam molten salt heat exchanger 61. The outlet of heat exchanger 61 is connected to the circulating water circuit 3. The circulating water circuit 3, the medium-temperature molten salt condensate heat exchanger 64, and the second generator set 7 are connected in sequence. Specifically, the fifth pipe 14 is connected to the steam inlet of the heating steam molten salt heat exchanger 61 via the second steam supply pipe 201. The outlet of the heating steam molten salt heat exchanger 61 is connected to the inlet of the deaerator 34 via the ninth pipe 18. The second pipe 11 is connected to the medium-temperature molten salt condensate heat exchanger 64 via the tenth pipe 19.

[0052] like Figure 2As shown, the system's loop 1 consists of boiler 1, circulating water circuit 3, high-temperature molten salt cold storage tank 55, first low-temperature molten salt pump 56, main steam molten salt heat exchanger 51, high-temperature molten salt heat storage tank 52, industrial steam user 8, and heating user 9. During operation, steam from boiler 1 is supplied entirely to the main steam molten salt heat exchanger 51 via the first steam supply pipeline 200, where it exchanges heat with the low-temperature molten salt to form high-temperature molten salt, which is then stored in the high-temperature molten salt heat storage tank 52. Most of the steam after heat exchange passes through the sixth pipeline 15, the seventh pipeline 16, the third pipeline 12, the fourth pipeline 13, and... The fifth pipe 14 flows to industrial steam users 8 and heating users 9 for heating. A small portion of the steam enters the deaerator 34 through the eighth pipe 17 to provide a heat source for the deaerator 34. At the same time, the water supply pipe 4 supplies water. Then, the steam enters the boiler 1 through the condenser 31, condensate pump 32, low-pressure heater 33, deaerator 34, and high-pressure heater 35 to supply water. This circuit removes the steam heat from the centralized heating system. The remaining steam heat is stored in molten salt to avoid heat loss. This is used during the winter heating season when electricity prices are negative to reduce the unit load and reduce power generation losses during this period.

[0053] like Figure 3 As shown, loop two within the system consists of boiler 1, circulating water circuit 3, high-temperature molten salt cold storage tank 55, first low-temperature molten salt pump 56, main steam molten salt heat exchanger 51, high-temperature molten salt hot storage tank 52, industrial steam user 8, medium-temperature molten salt cold storage tank 65, second low-temperature molten salt pump 66, heating steam molten salt heat exchanger 61, and medium-temperature molten salt hot storage tank 62. During operation, steam from boiler 1 is supplied entirely to the main steam molten salt heat exchanger 51 through the first steam supply pipeline 200, where it exchanges heat with the low-temperature molten salt to form high-temperature molten salt, which is stored in the high-temperature molten salt hot storage tank 52. Most of the steam after heat exchange flows to industrial steam user 8 through the sixth pipeline 15, the seventh pipeline 16, the third pipeline 12, and the fourth pipeline 13, while a small portion of the steam enters the desulfurization and desulfurization pipeline 8 through the eighth pipeline 17. In the oxygenator 34, steam is not supplied to heating user 9 at this time. The portion of steam originally supplied to heating user 9 enters the heating steam molten salt heat exchanger 61 through the second steam supply pipe 201, and exchanges heat with low-temperature molten salt to form medium-temperature molten salt, which is stored in the medium-temperature molten salt heat storage tank 62 to store this portion of steam heat and prevent heat loss. At the same time, water is supplied through the water supply pipe 4, and then water enters the boiler 1 through the condenser 31, condensate pump 32, low-pressure heater 33, deaerator 34 and high-pressure heater 35 to supply water. This circuit sends out the steam heat for centralized heating, and the remaining steam heat is stored in molten salt to prevent heat loss. It is used during non-winter heating periods with negative electricity prices to reduce the unit load during this period, store steam heat, prevent steam loss, and reduce power generation losses.

[0054] like Figure 4As shown, the system's loop three includes three branch loops. Branch loop one consists of boiler 1, first generator set 2, and circulating water circuit 3. During operation, all the steam in boiler 1 enters the high-pressure cylinder 21 and intermediate-pressure cylinder 22, driving the first generator 24 to generate electricity. Simultaneously, the low-temperature steam in the low-pressure cylinder 23 enters the condenser and condenses into water. Then, it enters boiler 1 to make up water via condensate pump 32, low-pressure heater 33, deaerator 34, and high-pressure heater 35. The high-temperature steam in the high-pressure cylinder 21 enters the high-pressure heater 35 to heat the circulating water. The intermediate-pressure cylinder... Steam from boiler 1 enters deaerator 34, and steam from low-pressure cylinder 23 enters low-pressure heater 33. All steam from boiler 1 is supplied to the first generator set 2 for centralized power generation, increasing unit revenue. Branch circuit two consists of a high-temperature molten salt thermal storage tank 52, a high-temperature molten salt pump 53, a high-temperature molten salt condensate heat exchanger 54, a high-temperature molten salt cold storage tank 55, a second pipeline 11, an industrial steam user 8, and a heating user 9. During operation, the high-temperature molten salt from the high-temperature molten salt thermal storage tank 52 enters the high-temperature molten salt condensate heat exchanger 54 via the high-temperature molten salt pump 53 for heating and circulation. Water is converted into steam and then stored in a high-temperature molten salt cold storage tank 55. The generated steam is supplied to industrial steam users 8 and heating users 9 through the third pipe 12, the fourth pipe 13, and the fifth pipe 14, so that heating is achieved entirely by heating the circulating water with steam from the high-temperature molten salt stored in the high-temperature molten salt hot storage tank 52, without wasting steam from boiler 1. Branch loop three consists of a medium-temperature molten salt hot storage tank 62, a medium-temperature molten salt pump 63, a medium-temperature molten salt condensate heat exchanger 64, a medium-temperature molten salt cold storage tank 65, a tenth pipe 19, and a second generator set 7. During operation, the medium-temperature molten salt hot water... The medium-temperature molten salt in storage tank 62 enters the medium-temperature molten salt condensate heat exchanger 64 via the medium-temperature molten salt pump 63, heating the circulating water into steam. The steam then enters the medium-temperature molten salt cold storage tank 65 for storage. The generated steam enters the second generator set 7 to generate electricity. This circuit is used during the winter heating season when the electricity price is positive. All the steam in boiler 1 is used for the first generator set 2 for centralized power generation and is not used for heating. The steam heat stored in the medium-temperature molten salt hot storage tank 62 is also used for power generation, increasing the power generation load and improving the unit's power generation revenue. Heating is achieved through circuit two, so there is no waste of steam from boiler 1.

[0055] like Figure 5As shown, loop four in the system includes the three branch loops in loop three mentioned above, excluding heating user 9. Branch loop two and branch loop three are connected through the second steam supply pipe 201. Specifically, the fifth pipe 14 is connected to the steam inlet of the heating steam molten salt heat exchanger 61 through the second steam supply pipe 201. A portion of the steam generated by heating the circulating water through the high-temperature molten salt condensate heat exchanger 54 enters the industrial steam user 8. At this time, no steam is supplied to heating user 9. The portion of steam originally supplied to heating user 9 enters the heating steam molten salt heat exchanger 61 through the second steam supply pipe 201, where it exchanges heat with the low-temperature molten salt to form medium-temperature molten salt, which is then stored in the medium-temperature molten salt heat storage tank 62. This loop is used during the non-winter period when the electricity price is positive. Unlike loop three, it can prevent the loss of the portion of steam supplied to heating user 9 and store it through molten salt, reducing unit losses.

[0056] Specifically, the control subsystem is the power plant control system, which operates the above-mentioned loop one, loop two, loop three and loop four respectively during each electricity price period to optimize unit processing and molten salt thermal storage heat release, and maximize revenue.

[0057] A method for a staged molten salt thermal storage coupled thermoelectric generator system includes the following steps:

[0058] like Figure 2-3 As shown, during periods of negative electricity prices, the first generator set 2 and the second generator set 7 do not operate, reducing the unit load. Boiler 1 supplies steam to the main steam molten salt heat storage and release subsystem 5. The main steam exchanges heat with the molten salt. The water supply pipe 4 supplies water to boiler 1 through the circulating water circuit 3. Specifically, all the steam from boiler 1 is supplied to the main steam molten salt heat exchanger 51 through the first steam supply pipe 200, and exchanges heat with the low-temperature molten salt to form high-temperature molten salt, which is stored in the high-temperature molten salt heat storage tank 52. At the same time, the first low-temperature molten salt pump 56 operates while the high-temperature molten salt pump 53 does not operate. Simultaneously, water is supplied through the water supply pipe 4, and then enters boiler 1 through the condenser 31, condensate pump 32, low-pressure heater 33, deaerator 34, and high-pressure heater 35 to replenish water. The first generator set 2 and the second generator set 7 do not operate, achieving the purpose of reducing the unit load. A portion of the steam heat from boiler 1 is stored first for later use, avoiding heat loss.

[0059] If it is during the winter period, such as Figure 2 As shown, most of the steam after heat exchange flows to industrial steam user 8 and heating user 9 via the sixth pipe 15, the seventh pipe 16, the third pipe 12, the fourth pipe 13 and the fifth pipe 14. A small portion of the steam enters the deaerator 34 for heating and to provide heat to the deaerator 34.

[0060] If it is during a non-winter period, such as Figure 3As shown, most of the steam after heat exchange flows to industrial steam user 8 via the sixth pipe 15, the seventh pipe 16, the third pipe 12, and the fourth pipe 13. A small portion of the steam enters the deaerator 34. At this time, no steam is supplied to heating user 9. The portion of steam originally supplied to heating user 9 enters the heating steam molten salt heat exchanger 61 via the second steam supply pipe 201. At the same time, the first low-temperature molten salt pump 56 operates while the medium-temperature molten salt pump 63 does not operate. The molten salt in the medium-temperature molten salt cold storage tank 65 is pumped into the heating steam molten salt heat exchanger 61 to exchange heat with the steam. Then, it enters the medium-temperature molten salt hot storage tank 62 for storage. The heat of the steam originally supplied to heating user 9 is stored again in the heating steam molten salt heat storage and release subsystem 6 to avoid heat loss. During periods of positive electricity price, steam is supplied to the second generator set 7 to generate electricity, increasing the electrical load.

[0061] like Figure 4-5 As shown, during periods of positive electricity prices, the first generator set 2 and the second generator set 7 operate respectively. All the steam in boiler 1 enters the high-pressure cylinder 21 and the intermediate-pressure cylinder 22, driving the first generator 24 to generate electricity. Simultaneously, the low-temperature steam in the low-pressure cylinder 23 enters the condenser and condenses into water. This water then flows through the condensate pump 32, low-pressure heater 33, deaerator 34, and high-pressure heater 35 to replenish water in boiler 1. At the same time, the medium-temperature molten salt pump 63 operates while the second low-temperature molten salt pump 66 does not operate. The molten salt in the medium-temperature molten salt heat storage tank 62 enters the medium-temperature molten salt condensate heat exchanger 64 via the medium-temperature molten salt pump 63 and... The circulating water supplied by the tenth pipeline 19 generates steam through heat exchange. The generated steam enters the second steam turbine 71 to drive the second generator 72 to generate electricity. At the same time, the high-temperature molten salt pump 53 operates while the first low-temperature molten salt pump 56 does not operate. The molten salt in the high-temperature molten salt heat storage tank 52 enters the high-temperature molten salt condensate heat exchanger 54 through the high-temperature molten salt pump 53 and exchanges heat with the circulating water supplied by the second pipeline 11 to generate steam. All the steam from the boiler 1 is used to generate electricity for the first generator set 2. At the same time, the heat stored in the heating steam molten salt heat storage and release subsystem 6 is used to generate electricity for the second generator set 7, thereby increasing peak power load output and increasing revenue.

[0062] If it is during the winter season, such as Figure 4 As shown, the generated steam is supplied to industrial steam user 8 and heating user 9 through the third pipe 12, the fourth pipe 13 and the fifth pipe 14, so that the heating is achieved by heating the circulating water with high temperature molten salt stored in the high temperature molten salt heat storage tank 52, without wasting the steam of boiler 1.

[0063] If it is during a non-winter period, such as Figure 5As shown, the fifth pipe 14 is connected to the steam inlet of the heating steam molten salt heat exchanger 61 through the second steam supply pipe 201. A portion of the steam generated by heating the circulating water through the high-temperature molten salt condensate heat exchanger 54 enters the industrial steam user 8. At this time, no steam is supplied to the heating user 9. The portion of steam originally supplied to the heating user 9 enters the heating steam molten salt heat exchanger 61 through the second steam supply pipe 201, where it exchanges heat with the low-temperature molten salt to form medium-temperature molten salt, which is stored in the medium-temperature molten salt heat storage tank 62 to avoid heat loss. The water in the heating steam molten salt heat exchanger 61 enters the deaerator 34 through the ninth pipe 18.

[0064] In summary, in the above methods, during the winter period with negative electricity prices, the first generator unit 2 and the second generator unit 7 stop generating electricity, and all the steam from boiler 1 is used for heating and for molten salt heat storage in the main steam molten salt heat storage subsystem 5, thereby reducing unit load and minimizing losses. During the non-winter period with negative electricity prices, a portion of the steam is used for heating, and the other portion is stored in the molten salt of the heating steam molten salt heat storage subsystem 6, reducing energy loss and minimizing losses. During the winter period with positive electricity prices, heating is achieved through the molten salt heat release of the main steam molten salt heat storage subsystem 5. During the non-winter period with positive electricity prices, the molten salt of the main steam molten salt heat storage subsystem 5... A portion of the steam generated from the heat release is supplied to the heating steam molten salt heat storage subsystem 6, where the steam heat is stored again by the molten salt, thereby reducing heat loss. During periods of positive electricity price, the first generator unit 2 uses the steam from boiler 1 to generate electricity, while the second generator unit 7 uses the heat stored during periods of negative electricity price to generate electricity, increasing the output load and generating more profit through centralized power generation. Thus, under the peak-valley electricity price policy, compared to setting up hot water storage tanks and electric thermal storage boilers 1 on the heating network side, peak shaving and valley filling and thermal decoupling during peak electricity periods are largely achieved, improving the operating economy of the units and increasing the power generation revenue of the units.

[0065] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention fall within the scope of protection claimed by the present invention.

Claims

1. A system for graded molten salt thermal storage coupled with a cogeneration unit in an electricity market, characterized in that, It includes a boiler, a first generator set, a circulating water system, a main steam molten salt heat storage and release subsystem, a heating steam molten salt heat storage and release subsystem, a second generator set, industrial steam users, heating users, and a control subsystem; The steam outlet of the boiler is connected to the steam inlet of the first generator set and the steam inlet of the main steam molten salt heat storage and release subsystem, respectively. The heat storage end steam outlet and the heat release end steam outlet of the main steam molten salt heat storage and release subsystem are connected to the industrial steam user and the heating user, respectively. The heat storage end steam inlet of the heating steam molten salt heat storage and release subsystem is connected to the heat storage end steam outlet and the heat release end steam outlet of the main steam molten salt heat storage and release subsystem, respectively. The heat release end steam outlet of the heating steam molten salt heat storage and release subsystem is connected to the steam inlet of the second generator set. The circulating water circuit is connected to the boiler, the first generator set, the main steam molten salt heat storage and release subsystem, and the heating steam molten salt heat storage and release subsystem respectively, to provide circulating water; The main steam molten salt heat storage and release subsystem includes a main steam molten salt heat exchanger, a high-temperature molten salt hot storage tank, a high-temperature molten salt pump, a high-temperature molten salt condensate heat exchanger, a high-temperature molten salt cold storage tank, and a first low-temperature molten salt pump connected in sequence. The first low-temperature molten salt pump is connected to the molten salt inlet of the main steam molten salt heat exchanger. The steam outlet of the boiler is connected to the steam inlet of the main steam molten salt heat exchanger. The steam outlet of the main steam molten salt heat exchanger is connected to the industrial steam user and the heating user. The circulating water circuit is connected to the water inlet of the high-temperature molten salt condensate heat exchanger. The steam outlet of the high-temperature molten salt condensate heat exchanger is connected to the industrial steam user and the heating user. The heating steam molten salt heat storage and release subsystem includes a heating steam molten salt heat exchanger, a medium-temperature molten salt heat storage tank, a medium-temperature molten salt pump, a medium-temperature molten salt condensate heat exchanger, a medium-temperature molten salt cold storage tank, and a second low-temperature molten salt pump connected in sequence. The second low-temperature molten salt pump is connected to the molten salt inlet of the heating steam molten salt heat exchanger. The steam outlet of the high-temperature molten salt condensate heat exchanger is connected to the steam inlet of the heating steam molten salt heat exchanger. The water outlet of the heating steam molten salt heat exchanger is connected to the circulating water circuit. The circulating water circuit, the medium-temperature molten salt condensate heat exchanger, and the second generator set are connected in sequence. The control subsystem controls the connection between the boiler's steam outlet and the main steam molten salt heat exchanger's steam inlet and the main steam molten salt heat exchanger's steam outlet and the industrial steam user during periods of negative electricity prices. During winter periods, it controls the connection between the main steam molten salt heat exchanger's steam outlet and the heating user, or during non-winter periods, it controls the connection between the main steam molten salt heat exchanger's steam outlet and the heating steam molten salt heat exchanger's steam inlet. The control subsystem controls the connection between the steam outlet of the boiler and the steam inlet of the first generator set during periods of positive electricity price, the connection between the steam outlet of the high-temperature molten salt condensate heat exchanger and the industrial steam user, and the connection between the steam outlet of the medium-temperature molten salt condensate heat exchanger and the steam inlet of the second generator set. During winter periods, it controls the connection between the steam outlet of the high-temperature molten salt condensate heat exchanger and the heating user, or during non-winter periods, it controls the connection between the steam outlet of the high-temperature molten salt condensate heat exchanger and the steam inlet of the heating steam molten salt heat exchanger.

2. The system of the graded molten salt thermal storage coupled thermoelectric generator according to claim 1, characterized in that, The circulating water circuit includes a water supply pipe, a condenser, a condensate pump, a low-pressure heater, a deaerator, and a high-pressure heater connected in sequence. The inlet of the condenser is connected to the steam outlet of the first generator set, and the outlet of the high-pressure heater is connected to the inlet of the boiler.

3. The system of the graded molten salt thermal storage coupled thermoelectric generator according to claim 2, characterized in that, The heat storage end outlet of the main steam molten salt heat storage and release subsystem is connected to the steam inlet of the deaerator.

4. The system of the graded molten salt thermal storage coupled thermoelectric generator according to claim 2, characterized in that, The first generator set includes a high-pressure cylinder, an intermediate-pressure cylinder, a low-pressure cylinder, and a first generator arranged coaxially. The steam inlets of the high-pressure cylinder and the intermediate-pressure cylinder are respectively connected to the steam outlet of the boiler. The steam outlet of the intermediate-pressure cylinder is connected to the steam inlet of the low-pressure cylinder. The steam outlet of the low-pressure cylinder is connected to the steam inlet of the low-pressure heater. The steam outlet of the intermediate-pressure cylinder is connected to the steam inlet of the deaerator. The steam outlet of the high-pressure cylinder is connected to the steam inlet of the high-pressure heater.

5. A method for a system of graded molten salt thermal storage coupled thermoelectric generator according to any one of claims 1-4, characterized in that, Includes the following steps: During periods of negative electricity prices, the first generator set and the second generator set do not operate. The boiler supplies steam to the main steam molten salt heat storage and release subsystem. The main steam exchanges heat with the heat storage end of the main steam molten salt heat storage and release subsystem. The circulating water circuit supplies water to the boiler. If it is winter, the steam after heat exchange will enter the industrial steam user and the heating user; If it is not winter, part of the steam after the heat exchange will enter the industrial steam user, and the other part will exchange heat with the heat storage end of the main steam molten salt heat storage and release subsystem, where the molten salt will store the heat of the steam. During periods of positive electricity prices, the first generator set and the second generator set operate separately. All the steam in the boiler enters the first generator set to generate electricity. The circulating water circuit supplies water to the boiler. The heat release end of the main steam molten salt storage and release subsystem releases molten salt heat and exchanges heat with the circulating water to generate steam. All the steam in the second generator set generates electricity. The heat release end of the main steam molten salt storage and release subsystem releases molten salt heat and exchanges heat with the circulating water to generate steam. During winter, all the steam generated at the heat release end of the main steam molten salt storage and heat release subsystem enters the industrial steam user and the heating user. During non-winter periods, part of the steam generated at the heat release end of the main steam molten salt storage and release subsystem enters the industrial steam user, while the other part exchanges molten salt heat with the heat storage end of the main steam molten salt storage and release subsystem, and the resulting water enters the aforementioned circulating water circuit.

6. A method for a system of graded molten salt thermal storage coupled thermoelectric generator according to claim 5, characterized in that, The main steam molten salt heat storage and release subsystem includes a main steam molten salt heat exchanger, a high-temperature molten salt hot storage tank, a high-temperature molten salt pump, a high-temperature molten salt condensate heat exchanger, a high-temperature molten salt cold storage tank, and a first low-temperature molten salt pump. The heating steam molten salt heat storage and release subsystem includes a heating steam molten salt heat exchanger, a medium-temperature molten salt hot storage tank, a medium-temperature molten salt pump, a medium-temperature molten salt condensate heat exchanger, a medium-temperature molten salt cold storage tank, and a second low-temperature molten salt pump, connected in sequence. During periods of negative electricity prices, all the steam in the boiler enters the main steam molten salt heat exchanger. At the same time, the first low-temperature molten salt pump operates while the high-temperature molten salt pump does not operate. Molten salt in the high-temperature molten salt cold storage tank is pumped into the main steam molten salt heat exchanger to exchange heat with the high-temperature steam, and then stored in the high-temperature molten salt hot storage tank. During the winter season, the steam that has undergone heat exchange in the main steam molten salt heat exchanger enters the industrial steam user and the heating user. During non-winter periods, after the steam has been heated by the main steam molten salt heat exchanger, part of it enters the industrial steam user and the other part enters the heating steam molten salt heat exchanger. At the same time, the second low-temperature molten salt pump is running while the medium-temperature molten salt pump is not running. Molten salt in the medium-temperature molten salt cold storage tank is pumped into the heating steam molten salt heat exchanger to exchange heat with the steam, and then stored in the medium-temperature molten salt hot storage tank.

7. A method for a system of graded molten salt thermal storage coupled to a thermoelectric generator according to claim 5, characterized in that, The main steam molten salt heat storage and release subsystem includes a main steam molten salt heat exchanger, a high-temperature molten salt hot storage tank, a high-temperature molten salt pump, a high-temperature molten salt condensate heat exchanger, a high-temperature molten salt cold storage tank, and a first low-temperature molten salt pump. The heating steam molten salt heat storage and release subsystem includes a heating steam molten salt heat exchanger, a medium-temperature molten salt hot storage tank, a medium-temperature molten salt pump, a medium-temperature molten salt condensate heat exchanger, a medium-temperature molten salt cold storage tank, and a second low-temperature molten salt pump, connected in sequence. During periods of positive electricity price, both the first and second generator sets operate. All the steam in the boiler enters the first generator set to generate electricity. Simultaneously, the medium-temperature molten salt pump operates while the second low-temperature molten salt pump does not operate. Molten salt in the medium-temperature molten salt thermal storage tank enters the medium-temperature molten salt condensate heat exchanger through the medium-temperature molten salt pump and exchanges heat with the circulating water to generate steam. The generated steam enters the second generator set to generate electricity. At the same time, the high-temperature molten salt pump operates while the first low-temperature molten salt pump does not operate. Molten salt in the high-temperature molten salt thermal storage tank enters the high-temperature molten salt condensate heat exchanger through the high-temperature molten salt pump and exchanges heat with the circulating water to generate steam. During the winter season, all the steam generated by the high-temperature molten salt condensate heat exchanger enters the industrial steam users and the heating users; During non-winter periods, part of the steam generated by the high-temperature molten salt condensate heat exchanger enters the industrial steam user, and the other part enters the heating steam molten salt heat exchanger. At the same time, the molten salt in the medium-temperature molten salt cold storage tank enters the heating steam molten salt heat exchanger through the second low-temperature molten salt pump and exchanges heat with the steam, and then enters the medium-temperature molten salt hot storage tank for storage.

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