Thermal power unit with near-zero output and control method thereof based on molten salt heat storage

Abstract

The application provides a thermal power unit near-zero output thermal system based on fused salt heat storage and a control method thereof, and belongs to the technical field of thermal power generation; the problems of insufficient duration of stewing and fire pressure peak shaving, the need for an oxygen remover and shaft seal steam provided on site during stewing and fire pressure peak shaving of a thermal power unit adopting a circulating fluidized bed boiler are solved; the thermal power unit comprises a high-pressure cylinder, a medium-pressure cylinder, a low-pressure cylinder and a boiler; the boiler is connected with the high-pressure cylinder through a main steam pipe; the boiler is connected with the medium-pressure cylinder through a reheated steam pipe; the medium-pressure cylinder is connected with the low-pressure cylinder through a medium-low pressure communication pipe; the low-pressure cylinder is connected with a condenser, a condensate pump, a low-pressure heater, an oxygen remover, a feed water pump, a high-pressure heater and the boiler through pipes in sequence; the low-pressure cylinder is connected with a fused salt heat storage device and a fused salt heat release device through steam inlet pipes; the fused salt heat release device is further connected with a shaft seal system and the oxygen remover through pipes; and the application is applied to the thermal power unit.

Description

Technical Field

[0001] This invention provides a near-zero output thermal power system for thermal power units based on molten salt thermal storage and its control method, belonging to the field of thermal power generation technology. Background Technology

[0002] With the integration of a large number of renewable energy sources into the grid, coal-fired power generating units will gradually transform from power-generating power sources to power sources that provide both basic security and system regulation. Therefore, fully utilizing existing coal-fired power generating units for peak-shaving retrofitting can effectively promote the absorption of renewable energy. Simultaneously, during periods of high renewable energy generation, a large number of coal-fired power units will need to operate at low loads for peak shaving. In this context, energy storage will play a crucial role. Configuring molten salt thermal energy storage systems can effectively improve the output regulation range of existing coal-fired power units, achieving flexible operation.

[0003] When a thermal power unit using a circulating fluidized bed boiler is shut down for peak shaving, it can operate without shutting down the boiler or disconnecting from the grid, achieving low-output operation. When the grid needs to increase load, the unit does not require turbine start-up or generator grid connection, achieving rapid recovery to normal operating levels, greatly improving peak shaving flexibility. However, the main problems are: 1. Due to factors such as turbine rotor overheating, the turbine unit output cannot be too low, and the heat consumption after shutdown is too fast, resulting in insufficient shutdown peak shaving time; 2. Circulating fluidized bed boiler units require temporary supply of steam for deaerators and shaft seals during shutdown peak shaving. These problems limit the unit's flexible operation capability. Summary of the Invention

[0004] To address the problems of insufficient shutdown and peak shaving time, the need for temporary deaerator supply, and the need for steam for shaft seals in existing thermal power units using circulating fluidized bed boilers, this invention proposes a near-zero output thermal power system for thermal power units based on molten salt thermal storage and its control method.

[0005] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: a near-zero output thermal power system for thermal power units based on molten salt thermal storage, including a high-pressure cylinder, an intermediate-pressure cylinder, a low-pressure cylinder, a boiler, a condenser, a condensate pump, a low-pressure heater, a deaerator, a feedwater pump, a high-pressure heater, a molten salt thermal storage tank, a low-temperature molten salt thermal storage tank, a low-temperature molten salt pump, a high-temperature molten salt thermal storage tank, a molten salt heat exchanger, a high-temperature molten salt pump, and a shaft sealing system. The boiler is connected to the high-pressure cylinder through a main steam pipe, the boiler is connected to the intermediate-pressure cylinder through a reheat steam pipe, the intermediate-pressure cylinder is connected to the low-pressure cylinder through an intermediate-low pressure connecting pipe, and the low-pressure cylinder is connected to the condenser, condensate pump, low-pressure heater, deaerator, feedwater pump, high-pressure heater, and boiler in sequence through pipelines.

[0006] The high-pressure cylinder is also connected to the condenser through its exhaust pipe, the medium-pressure cylinder is also connected to the condenser through its exhaust pipe, the low-pressure cylinder is connected to the molten salt heat storage tank and the molten salt heat releaser through its steam inlet pipe, and the molten salt heat releaser is also connected to the shaft sealing system and the deaerator through pipelines.

[0007] The molten salt heat storage device is connected to the molten salt heat release device via a high-temperature molten salt heat storage tank and a high-temperature molten salt pump.

[0008] The condenser is also connected to the molten salt heat storage tank and the molten salt heat releaser via pipelines.

[0009] Valves are installed on each pipeline.

[0010] The molten salt heat storage device is also connected to a low-temperature molten salt heat storage tank, a low-temperature molten salt pump, and a molten salt heat release device.

[0011] The main steam pipe of the high-pressure cylinder is equipped with a first valve, and the exhaust pipe of the high-pressure cylinder is equipped with a second valve.

[0012] A third valve is installed on the reheat steam pipe, and a fourth valve is installed on the medium and low pressure connecting pipe.

[0013] A fifth valve is installed on the exhaust pipe connecting the high-pressure cylinder and the condenser.

[0014] A sixth valve is installed on the exhaust pipe connecting the intermediate pressure cylinder and the condenser;

[0015] The main pipe of the steam inlet pipe connecting the low-pressure cylinder to the molten salt heat storage tank and the molten salt heat releaser is equipped with a seventh valve, the branch pipe connected to the molten salt heat storage tank is equipped with an eighth valve, and the branch pipe connected to the molten salt heat releaser is equipped with a ninth valve.

[0016] The molten salt exothermic device is connected to the shaft sealing system via the tenth valve and to the deaerator via the eleventh valve.

[0017] The molten salt heat storage tank is connected to the outlet of the condensate pump via the 12th valve and the 13th valve, and is also connected to the condenser via the 14th valve and the molten salt heat exchanger via the 15th valve.

[0018] A control method for a near-zero output thermal power unit based on molten salt thermal storage, comprising the following steps:

[0019] When the thermal power unit does not need to reduce peak load, the molten salt system operates in thermal storage mode, with the first, second, third, fourth, seventh, eighth, twelfth, and fourteenth valves all in the open state, and the fifth, sixth, ninth, tenth, eleventh, thirteenth, and fifteenth valves all in the closed state.

[0020] The main steam generated by the boiler enters the high-pressure cylinder through the first valve to do work. The exhaust steam from the high-pressure cylinder enters the boiler for reheating through the second valve. The reheated steam enters the intermediate-pressure cylinder through the third valve to do work. The exhaust steam from the intermediate-pressure cylinder enters the low-pressure cylinder through the fourth valve on the medium-low pressure connecting pipe to continue doing work. The exhaust steam from the low-pressure cylinder enters the condenser and condenses into water. After passing through the condensate pump, low-pressure heater, deaerator, feedwater pump, and high-pressure heater, it enters the boiler for heating.

[0021] The exhaust steam from the intermediate pressure cylinder enters the molten salt heat storage tank to heat the molten salt, and the condensate after heat exchange enters the condenser.

[0022] Start the cryogenic molten salt pump. The cryogenic molten salt in the cryogenic molten salt storage tank is heated by the molten salt storage device and becomes high-temperature molten salt. Then it enters the high-temperature molten salt storage tank to store the heat.

[0023] A control method for a near-zero output thermal power unit based on molten salt thermal storage, comprising the following steps:

[0024] When the thermal power unit needs to reduce peak output to near zero, the molten salt system operates in an exothermic mode.

[0025] The main steam generated by the boiler enters the high-pressure cylinder through the first valve to do work; the second valve is gradually closed and the fifth valve is slowly opened so that most of the exhaust steam after the high-pressure cylinder has done work enters the condenser and a small amount of exhaust steam enters the boiler reheater to prevent overheating; when the circulating fluidized bed boiler unit is shut down and the fire is turned off, the second valve is completely closed if the boiler reheater is monitored to ensure that it does not overheat.

[0026] Close valves 3, 8, 12, and 14; open valves 6, 7, 9, 10, 11, 13, and 15.

[0027] Start the high-temperature molten salt pump. The high-temperature molten salt in the high-temperature molten salt storage tank releases heat through the molten salt heat releaser and becomes low-temperature molten salt before entering the low-temperature molten salt storage tank.

[0028] The low-temperature condensate from the condenser passes through the condensate pump. Part of it goes through the low-pressure heater, deaerator, feedwater pump, and high-pressure heater before entering the boiler for heating. The other part goes through the thirteenth valve and the fifteenth valve into the molten salt exothermic heater to absorb the exothermic heat from the high-temperature molten salt and become regenerated steam.

[0029] Part of the regenerated steam is supplied to the shaft sealing system through the tenth valve; part is supplied to the deaerator through the eleventh valve; the remaining steam passes through the ninth and seventh valves and reaches the inlet of the low-pressure cylinder. Part of it passes through the fourth valve on the medium-low pressure connecting pipe and enters the outlet of the medium-pressure cylinder to cool the last stage blades of the medium-pressure rotor before entering the condenser to be cooled into condensate. The other part enters the low-pressure cylinder to cool the low-pressure rotor blades, and then is discharged into the condenser to be cooled into condensate.

[0030] The advantages of this invention over the prior art are as follows:

[0031] This invention introduces a small amount of steam into the high-pressure cylinder and no steam into the intermediate-pressure cylinder. The cooling steam heat required for the intermediate and low-pressure rotor blades is provided by the molten salt heat storage and release system, which greatly reduces the heat consumption after the circulating fluidized bed boiler unit is shut down and significantly extends the peak shaving time. The thermal power unit can maintain operation for 3-5 hours at an output of 0-5MW without disconnecting the grid.

[0032] This invention provides steam for the deaerator and shaft seals when the molten salt heat storage and release system is running in a near-zero output mode in thermal power units, thus enabling near-zero output operation of circulating fluidized bed boiler units during single-unit operation.

[0033] This invention ensures that the thermal power unit is in a near-zero output condition by introducing a small amount of steam into the high-pressure cylinder, and provides the cooling steam required for the medium and low-pressure rotor blades by using the regenerated steam generated by the molten salt heat storage and release system, thus ensuring the safe operation of the thermal power unit when it is in a near-zero output condition.

[0034] The system of the present invention can operate in both the thermal storage mode and the heat release mode of the molten salt system, and can switch between them without disturbance.

[0035] This invention can be used for the design of new generating units, as well as for the near-zero output flexibility retrofit of thermal power units. It is particularly suitable for the retrofit of existing circulating fluidized bed boiler units for stoking and peak shaving operations. Attached Figure Description

[0036] The present invention will be further described below with reference to the accompanying drawings:

[0037] Figure 1 This is a schematic diagram of the thermal system structure of the molten salt system in the thermal storage operation mode of the present invention;

[0038] Figure 2 This is a schematic diagram of the thermal system structure of the present invention in the exothermic operation mode of the molten salt system;

[0039] In the diagram: 1 is the high-pressure cylinder, 2 is the medium-pressure cylinder, 3 is the low-pressure cylinder, 4 is the boiler, 5 is the first valve, 6 is the second valve, 7 is the third valve, 8 is the fourth valve, 9 is the condenser, 10 is the condensate pump, 11 is the low-pressure heater, 12 is the deaerator, 13 is the feedwater pump, 14 is the high-pressure heater, 15 is the seventh valve, 16 is the eighth valve, 17 is the molten salt thermal storage tank, 18 is the twelfth valve, 19 is the fourteenth valve, 20 is the low-temperature molten salt thermal storage tank, 21 is the low-temperature molten salt pump, 22 is the high-temperature molten salt thermal storage tank, 23 is the fifth valve, 24 is the sixth valve, 25 is the thirteenth valve, 26 is the fifteenth valve, 27 is the molten salt exothermic device, 28 is the ninth valve, 29 is the high-temperature molten salt pump, 30 is the tenth valve, 31 is the shaft sealing system, and 32 is the eleventh valve. Detailed Implementation

[0040] like Figure 1 and Figure 2 As shown, the present invention provides a near-zero output thermal power system for thermal power units based on molten salt thermal storage, including a high-pressure cylinder 1, an intermediate-pressure cylinder 2, a low-pressure cylinder 3, a boiler 4, a condenser 9, a condensate pump 10, a low-pressure heater 11, a deaerator 12, a feedwater pump 13, a high-pressure heater 14, a molten salt thermal storage tank 17, a low-temperature molten salt thermal storage tank 20, a low-temperature molten salt pump 21, a high-temperature molten salt thermal storage tank 22, a molten salt heat exchanger 27, a high-temperature molten salt pump 29, and a shaft sealing system 31.

[0041] The boiler 4 is connected to the high-pressure cylinder 1 via a main steam pipe. A first valve 5 is installed on the main steam pipe, and a second valve 6 is installed on the exhaust pipe of the high-pressure cylinder. The boiler 4 is connected to the intermediate-pressure cylinder 2 via a reheat steam pipe. A third valve 7 is installed on the reheat steam pipe. The intermediate-pressure cylinder 2 is connected to the low-pressure cylinder 3 via a medium-low pressure connecting pipe. A fourth valve 8 is installed on the medium-low pressure connecting pipe. The low-pressure cylinder 3 is connected in series with the condenser 9, condensate pump 10, low-pressure heater 11, deaerator 12, feedwater pump 13, and high-pressure heater 14 via pipelines.

[0042] The high-pressure cylinder 1 is also connected to the condenser 9 through the fifth valve 23 on the exhaust pipe; the medium-pressure cylinder 2 is also connected to the condenser 9 through the sixth valve 24 on the exhaust pipe; the low-pressure cylinder 3 is also connected to the molten salt heat storage tank 17 through the seventh valve 15 on the steam inlet pipe and then through the eighth valve 16, and at the same time connected to the molten salt heat releaser 27 through the ninth valve 28.

[0043] The molten salt exothermic device 27 is connected to the ninth valve 28 and also to the shaft sealing system 31 via the tenth valve 30, and to the deaerator 12 via the eleventh valve 32.

[0044] The molten salt heat storage tank 17 is connected to the outlet of the condensate pump 10 via the twelfth valve 18 and the thirteenth valve 25, and is also connected to the condenser 9 via the fourteenth valve 19, and to the molten salt heat releaser 27 via the fifteenth valve 26.

[0045] The molten salt heat storage device 17 is also connected to the molten salt heat release device 27 via the high-temperature molten salt heat storage tank 22 and the high-temperature molten salt pump 29. At the same time, the molten salt heat release device 27 is also connected to the molten salt heat storage device 17 via the low-temperature molten salt heat storage tank 20 and the low-temperature molten salt pump 21.

[0046] A control method for a near-zero output thermal power system of a thermal power unit based on molten salt thermal storage includes two scenarios. Figure 1 This is a schematic diagram of the thermal storage operation mode of the molten salt system according to the present invention.

[0047] When the thermal power unit does not require downward peak regulation, the molten salt system operates in thermal storage mode. Valve 5, valve 6, valve 7, valve 8, valve 15, valve 16, valve 18, and valve 19 are all open, while valves 23, 24, 28, 30, 32, 25, and 26 are all closed. The main steam generated by boiler 4 enters high-pressure cylinder 1 through valve 5 to perform work. The exhaust steam from high-pressure cylinder 1 enters boiler 4 through valve 6 for reheating. The reheated steam enters intermediate-pressure cylinder 2 through valve 7 to perform work. The exhaust steam from intermediate-pressure cylinder 2 enters low-pressure cylinder 3 through valve 8 on the intermediate-low pressure connecting pipe to continue performing work. The exhaust steam from low-pressure cylinder 3 enters condenser 9, condenses into water, and then passes through condensate pump 10, low-pressure heater 11, deaerator 12, feedwater pump 13, and high-pressure heater 14 before entering boiler 4 for heating. The exhaust steam from the intermediate-pressure cylinder 2 can enter the molten salt heat storage tank 17 to heat the molten salt, and the condensate after heat exchange enters the condenser 9. The low-temperature molten salt pump 21 is started, and the low-temperature molten salt in the low-temperature molten salt heat storage tank 20 is heated by the molten salt heat storage tank 17 to become high-temperature molten salt, and then enters the high-temperature molten salt heat storage tank 22 to store the heat.

[0048] Figure 2 This is a schematic diagram of the structure of the present invention in the exothermic operation mode of the molten salt system.

[0049] When the thermal power unit needs to reduce peak output to near zero, the molten salt system operates in exothermic mode. The main steam generated by boiler 4 enters the high-pressure cylinder 1 through the first valve 5 to perform work; the second valve 6 is gradually closed, and the fifth valve 23 is slowly opened, so that most of the exhaust steam from the high-pressure cylinder 1 enters the condenser 9, and a small amount enters the boiler reheater to prevent overheating; after the circulating fluidized bed boiler unit is shut down, the second valve 6 is completely closed, provided the boiler reheater does not overheat. The third valve 7, eighth valve 16, twelfth valve 18, and fourteenth valve 19 are closed, and the sixth valve 24, seventh valve 15, ninth valve 28, tenth valve 30, eleventh valve 32, thirteenth valve 25, and fifteenth valve 26 are opened. The high-temperature molten salt pump 29 is started, and the high-temperature molten salt in the high-temperature molten salt storage tank 22 is converted to low-temperature molten salt through the molten salt exothermic device 27 and then enters the low-temperature molten salt storage tank 20. The low-temperature condensate from condenser 9, after passing through condensate pump 10, is divided into two parts: one part passes through low-pressure heater 11, deaerator 12, feedwater pump 13, and high-pressure heater 14 before entering boiler 4 for heating; the other part passes through thirteenth valve 25 and fifteenth valve 26 before entering molten salt exothermic heater 27 to absorb the exothermic heat from high-temperature molten salt and become regenerated steam. Part of this regenerated steam passes through tenth valve 30 to supply shaft sealing system 31; part passes through eleventh valve 32 to supply deaerator 12; the remaining steam passes through ninth valve 28 and seventh valve 15 to reach the inlet of low-pressure cylinder 3. Part of this steam passes through fourth valve 8 on the medium-low pressure connecting pipe to enter the outlet of medium-pressure cylinder 2 to cool the last stage blades of the medium-pressure rotor before entering condenser 9 to be cooled into condensate; the other part enters low-pressure cylinder 3 to cool the low-pressure rotor blades before being discharged into condenser 9 to be cooled into condensate.

[0050] The fourth valve 8 on the medium-low pressure connecting pipe is always open. When the molten salt system is in heat storage mode, the exhaust steam from the medium-pressure cylinder 2 enters the low-pressure cylinder 3 through the fourth valve 8 to continue doing work; when the molten salt system is in heat release mode, part of the regenerated steam passes through the ninth valve 28 and the seventh valve 15 to reach the steam inlet of the low-pressure cylinder 3, and part of it passes through the fourth valve 8 to enter the exhaust port of the medium-pressure cylinder 2 to cool the last stage blades of the medium-pressure rotor before entering the condenser 9.

[0051] The near-zero output thermal power system for thermal power units proposed in this invention is mainly achieved by adding a molten salt heat storage and release module and optimizing the steam process. This effectively extends the peak-shaving operation time of circulating fluidized bed boiler units during shutdown and pressure-down operation, and also enables peak-shaving operation of circulating fluidized bed boiler units during single-unit operation. Normally, when the thermal power unit does not require downward peak shaving, the molten salt system, operating in heat storage mode, draws a portion of the steam from the thermal power unit to the molten salt heat storage and release module to store the heat. When the output of a thermal power unit needs to be adjusted down to near zero, the molten salt heat storage and release module returns the heat to the thermal power unit, providing steam for the deaerator, shaft seals, and cooling steam for the medium and low-pressure rotor blades. This enables the circulating fluidized bed boiler unit to operate near zero output during single-unit operation. At the same time, by introducing a small amount of steam into the high-pressure cylinder and not introducing steam into the medium-pressure cylinder, the cooling steam required for the medium and low-pressure rotor blades is provided by the molten salt heat storage and release system. This method greatly reduces the heat consumption after the circulating fluidized bed boiler unit is shut down, significantly extends the peak shaving time during shutdown, and meets the needs of flexible operation of the power system.

[0052] Regarding the specific structure of this invention, it should be noted that the connection relationships between the various component modules are definite and achievable. Unless otherwise specified in the embodiments, these specific connection relationships can bring about corresponding technical effects and solve the technical problems proposed by this invention without relying on the execution of corresponding software programs. The models of the components, modules, and specific parts appearing in this invention, their interconnection methods, and the conventional usage methods and expected technical effects brought about by the above technical features, unless specifically described, are all publicly disclosed content in patents, journal articles, technical manuals, technical dictionaries, and textbooks that could be obtained by those skilled in the art before the application date, or belong to existing technologies such as conventional technology and common knowledge in the field. Therefore, no further explanation is needed, making the technical solution provided in this case clear, complete, and achievable, and enabling the reproduction or acquisition of corresponding physical products based on this technical means.

[0053] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A control method for a near-zero output thermal power system of a thermal power unit based on molten salt thermal storage, characterized in that: The system includes a high-pressure cylinder, an intermediate-pressure cylinder, a low-pressure cylinder, a boiler, a condenser, a condensate pump, a low-pressure heater, a deaerator, a feedwater pump, a high-pressure heater, a molten salt thermal storage tank, a low-temperature molten salt thermal storage tank, a low-temperature molten salt pump, a high-temperature molten salt thermal storage tank, a molten salt heat exchanger, a high-temperature molten salt pump, and a shaft sealing system. The boiler is connected to the high-pressure cylinder via a main steam pipe, and the boiler is connected to the intermediate-pressure cylinder via a reheat steam pipe. The intermediate-pressure cylinder is connected to the low-pressure cylinder via a medium-low pressure connecting pipe. The low-pressure cylinder is connected in sequence to the condenser, condensate pump, low-pressure heater, deaerator, feedwater pump, high-pressure heater, and boiler via pipelines. The high-pressure cylinder is also connected to the condenser through its exhaust pipe, the medium-pressure cylinder is also connected to the condenser through its exhaust pipe, the low-pressure cylinder is connected to the molten salt heat storage tank and the molten salt heat releaser through its steam inlet pipe, and the molten salt heat releaser is also connected to the shaft sealing system and the deaerator through pipelines. The molten salt heat storage device is connected to the molten salt heat release device via a high-temperature molten salt heat storage tank and a high-temperature molten salt pump. The condenser is also connected to the molten salt heat storage tank and the molten salt heat releaser via pipelines. Each pipeline is equipped with a valve; wherein the main steam pipe of the high-pressure cylinder is equipped with a first valve, the exhaust pipe of the high-pressure cylinder is equipped with a second valve; the reheat steam pipe is equipped with a third valve, the medium and low pressure connecting pipe is equipped with a fourth valve; and the exhaust pipe of the high-pressure cylinder connected to the condenser is equipped with a fifth valve. A sixth valve is installed on the exhaust pipe connecting the intermediate pressure cylinder and the condenser; The main pipe of the steam inlet pipe connecting the low-pressure cylinder to the molten salt heat storage tank and the molten salt heat releaser is equipped with a seventh valve, the branch pipe connected to the molten salt heat storage tank is equipped with an eighth valve, and the branch pipe connected to the molten salt heat releaser is equipped with a ninth valve. The molten salt exothermic device is connected to the shaft sealing system through the tenth valve and to the deaerator through the eleventh valve. The molten salt heat storage tank is connected to the outlet of the condensate pump via the 12th valve and the 13th valve, and is also connected to the condenser via the 14th valve and the molten salt heat exchanger via the 15th valve. The method includes the following steps: When thermal power units need to reduce peak output to near-zero conditions, the molten salt system operates in an exothermic mode. The main steam generated by the boiler enters the high-pressure cylinder through the first valve to do work; the second valve is gradually closed and the fifth valve is slowly opened so that most of the exhaust steam after the high-pressure cylinder has done work enters the condenser and a small amount of exhaust steam enters the boiler reheater to prevent overheating. After the circulating fluidized bed boiler unit is shut down and the fire is turned off, the second valve is completely closed, provided that the boiler reheater is not overheating. Close valves 3, 8, 12, and 14; open valves 6, 7, 9, 10, 11, 13, and 15. Start the high-temperature molten salt pump. The high-temperature molten salt in the high-temperature molten salt storage tank releases heat through the molten salt heat releaser and becomes low-temperature molten salt before entering the low-temperature molten salt storage tank. The low-temperature condensate from the condenser passes through the condensate pump. Part of it goes through the low-pressure heater, deaerator, feedwater pump, and high-pressure heater before entering the boiler for heating. The other part goes through the thirteenth valve and the fifteenth valve into the molten salt exothermic heater to absorb the exothermic heat from the high-temperature molten salt and become regenerated steam. Part of the regenerated steam is supplied to the shaft sealing system through the tenth valve; part is supplied to the deaerator through the eleventh valve; the remaining steam passes through the ninth and seventh valves and reaches the inlet of the low-pressure cylinder. Part of it passes through the fourth valve on the medium-low pressure connecting pipe and enters the outlet of the medium-pressure cylinder to cool the last stage blades of the medium-pressure rotor before entering the condenser to be cooled into condensate. The other part enters the low-pressure cylinder to cool the low-pressure rotor blades, and then is discharged into the condenser to be cooled into condensate.

2. The control method for a near-zero output thermal power system of a thermal power unit based on molten salt thermal storage according to claim 1, characterized in that: The molten salt heat storage device is also connected to a low-temperature molten salt heat storage tank, a low-temperature molten salt pump, and a molten salt heat release device.

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