Protective gas energy recovery system based on molten salt heat storage

Abstract

The application relates to the technical field of molten salt heat storage, in particular to a protective gas residual energy recovery system based on molten salt heat storage. The protective gas residual energy recovery system comprises a molten salt heat storage unit, a protective gas supply unit and a protective gas residual energy recovery unit. The molten salt heat storage unit comprises a molten salt heater and a molten salt storage tank, molten salt heated by the molten salt heater is introduced into the molten salt storage tank; the protective gas supply unit introduces protective gas into the molten salt storage tank to isolate the molten salt from air; the protective gas residual energy recovery unit is communicated with a protective gas outlet of the molten salt storage tank and receives the protective gas discharged from the molten salt storage tank; the protective gas residual energy recovery unit comprises a turbine, and the protective gas entering the protective gas residual energy recovery unit drives the turbine to work. The protective gas residual energy recovery system can efficiently recover the residual energy in the protective gas and reduce the energy consumption required in the protective gas conveying process to a certain extent.

Description

Technical Field

[0001] This invention relates to the field of molten salt thermal energy storage technology, specifically to a protective gas residual energy recovery system based on molten salt thermal energy storage. Background Technology

[0002] In the field of molten salt thermal energy storage, ternary nitrites (such as mixtures of sodium nitrate, potassium nitrate, and sodium nitrite) are widely used in solar thermal power generation and industrial waste heat recovery due to their low melting point (140-160 ℃), high thermal density, and good thermal conductivity. However, these molten salts are prone to oxidation reactions with oxygen in the air at high temperatures, leading to component deterioration and equipment corrosion. Therefore, an inert atmosphere (such as nitrogen) is required as a protective gas to maintain the inert environment of the system, thereby preventing the molten salt from contacting the air.

[0003] In existing technologies, the protective gas covering the molten salt surface is typically discharged directly after completing its air isolation function, resulting in the ineffective utilization of its residual heat (usually 300-500 °C) and thus a certain degree of energy waste. Furthermore, traditional molten salt thermal storage systems usually rely on external power equipment (such as air pumps) to maintain the transport and discharge of the protective gas. This gas transport process is typically energy-intensive, increasing the overall operating cost of the system. Summary of the Invention

[0004] To address the above problems, this invention provides a protective gas residual energy recovery system based on molten salt thermal storage, which can efficiently recover the residual energy in the protective gas and reduce the energy consumption required during the protective gas transportation process to a certain extent.

[0005] This invention provides a protective gas waste energy recovery system based on molten salt thermal storage, the recovery system comprising:

[0006] The molten salt thermal storage unit includes a molten salt heater and a molten salt storage tank, wherein molten salt heated by the molten salt heater is introduced into the molten salt storage tank;

[0007] The protective gas supply unit supplies protective gas to the molten salt storage tank to isolate the molten salt from air.

[0008] The protective gas residual energy recovery unit is connected to the protective gas outlet of the molten salt storage tank and receives the protective gas discharged from the molten salt storage tank.

[0009] The protective gas residual energy recovery unit includes a turbine, and the protective gas entering the protective gas residual energy recovery unit drives the turbine to do work.

[0010] Optionally, the molten salt thermal storage unit also includes:

[0011] A steam generator is connected to the molten salt storage tank to exchange heat with the molten salt in the tank.

[0012] Steam turbine: Steam generated by heat exchange in steam generator enters steam turbine to do work;

[0013] The first power generation unit is mechanically connected to the steam turbine, and the steam turbine drives the first power generation unit to generate electricity.

[0014] Optionally, the protective gas supply unit includes:

[0015] The pressure regulating valve adjusts the pressure of the protective gas released by the protective gas supply unit.

[0016] A pressure sensor is connected to the molten salt storage tank.

[0017] An oxygen content sensor is installed and connected to the molten salt storage tank.

[0018] The pressure regulating valve is connected in communication with the pressure sensor and the oxygen content sensor. Based on the monitoring values ​​of the pressure sensor and the oxygen content sensor, the valve opening is adjusted.

[0019] Optionally, the protective gas supplied in the protective gas supply unit may be nitrogen.

[0020] Optionally, the protective gas waste energy recovery unit also includes:

[0021] The second power generation device is mechanically connected to the turbine, and the turbine drives the second power generation device to generate electricity.

[0022] The condenser is connected to the protective gas outlet of the turbine and is used to recover the residual heat energy of the protective gas discharged from the turbine.

[0023] Optionally, the protective gas waste energy recovery unit also includes:

[0024] The vent pipe is connected to the protective gas outlet of the condenser, and the protective gas that has completed the recovery of residual energy is vented through the vent pipe.

[0025] Optionally, the protective gas waste energy recovery unit also includes:

[0026] A vacuum pump is installed between the condenser and the exhaust port of the vent pipe.

[0027] Optionally, the molten salt thermal storage unit also includes a temperature sensor to monitor temperature changes within the molten salt thermal storage unit;

[0028] The starting operating conditions for the protective gas supply unit and the protective gas residual energy recovery unit are: the temperature inside the molten salt thermal storage unit rises to a threshold value as monitored by a temperature sensor.

[0029] Optionally, the gas pressure inside the turbine is higher than the gas pressure inside the condenser. The protective gas pressure difference in the protective gas residual energy recovery unit is used to drive the protective gas to the condenser and discharge it through the vent pipe.

[0030] Optionally, the steam inlet of the condenser is connected to the steam outlet of the steam turbine, and the steam is cooled by the condenser before entering the steam generator.

[0031] In the protective gas residual energy recovery system based on molten salt thermal storage provided by this invention, a protective gas supply unit covers the surface of the molten salt with protective gas, preventing the molten salt from oxidizing and deteriorating upon contact with air after heating. Simultaneously, during the contact process between the high-temperature molten salt and the protective gas, some energy is transferred to the protective gas, resulting in the protective gas carrying residual energy such as thermal and pressure energy after completing its function of isolating the molten salt from air. This recovery system, by incorporating a protective gas residual energy recovery unit, recovers the residual energy contained in the protective gas and converts it into other readily usable energy forms via equipment such as a turbine, thereby improving the efficiency of further energy utilization. Attached Figure Description

[0032] Figure 1 This is a schematic diagram of a protective gas residual energy recovery system based on molten salt thermal storage provided by an embodiment of the present invention.

[0033] Reference numerals: 100-Protective gas residual energy recovery system, 1-Molten salt heater, 11-Feeding pipe, 12-Discharge pipe, 2-Low-temperature molten salt tank, 21-Vent pipe, 22-Material pipe, 23-Cold salt pump, 24-Cold tank pressure sensor, 3-High-temperature molten salt tank, 31-Vent pipe, 32-Hot salt pump, 33-Hot tank pressure sensor, 4-Nitrogen tank, 41-Pressure regulating valve, 42-Gas supply pipe, 5-Steam generator, 6-Steam turbine, 7-First power generation unit, 8-Turbine, 81-Vent pipe, 9-Second power generation unit, 101-Condenser, 102-Exhaust pipe, 103-Vacuum pump. Detailed Implementation

[0034] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0035] In response to the common practice of using protective gas to prevent molten salt oxidation in existing molten salt thermal storage processes, this embodiment provides a protective gas waste energy recovery system 100 based on molten salt thermal storage to recover the residual energy carried in the protective gas after use, thereby further improving energy utilization efficiency. This protective gas waste energy recovery system 100 includes a molten salt thermal storage unit, a protective gas supply unit, and a protective gas waste energy recovery unit. The molten salt thermal storage unit includes a molten salt heater 1 and a molten salt storage tank. Molten salt heated by the molten salt heater 1 is introduced into the molten salt storage tank. The protective gas supply unit introduces protective gas into the molten salt storage tank to isolate the molten salt from air. The protective gas waste energy recovery unit is connected to the protective gas outlet of the molten salt storage tank and receives the protective gas discharged from the molten salt storage tank. The protective gas waste energy recovery unit includes a turbine 8. The protective gas discharged from the protective gas outlet of the high-temperature molten salt tank 3 enters the turbine 8 installed in the protective gas waste energy recovery unit along the gas outlet pipe 31 and drives the turbine 8 to perform work.

[0036] Figure 1 This is a schematic diagram of a protective gas waste energy recovery system 100 based on molten salt thermal storage provided in this embodiment. (Reference) Figure 1 The molten salt storage tank adopts a dual-tank design, specifically including a cryogenic molten salt tank 2 and a high-temperature molten salt tank 3. A feed pipe 11 connects the molten salt inlet of the cryogenic molten salt tank 2 to the molten salt inlet of the molten salt heater 1; a discharge pipe 12 connects the molten salt inlet of the high-temperature molten salt tank 3 to the molten salt outlet of the molten salt heater 1, and the molten salt outlet of the high-temperature molten salt tank 3 is connected to the molten salt inlet of the cryogenic molten salt tank 2. The molten salt inlet of the cryogenic molten salt tank 2 and the molten salt outlet of the high-temperature molten salt tank 3 are connected by a feed pipe 22. To ensure high structural strength and adaptability to high-temperature and high-pressure conditions, the molten salt storage tank in this embodiment is a spherical tank design. In other embodiments, the shape of the molten salt storage tank can be designed in other forms according to the specific operating environment and heat storage indicators; no specific limitations are imposed here.

[0037] In this embodiment, the energy stored in the molten salt thermal storage unit comes from solar radiation. The molten salt heater 1 specifically employs a solar thermal collector, which is composed of serpentine absorber tube panels. The interior of the absorber tube panels contains flowing molten salt. When the surface of the absorber tube panel receives solar radiation focused by a mirror field, heat conduction occurs between the inner and outer walls of the absorber tube panel, and convective heat exchange occurs between the inner wall and the flowing molten salt within the absorber tube panel. In other embodiments, the molten salt heater 1 can be selected or designed with other types of collectors depending on the thermal storage object and scenario; no specific limitations are imposed here.

[0038] To ensure smooth flow of the molten salt thermal storage medium within the molten salt thermal storage unit, this embodiment further includes a cold salt pump 23 and a hot salt pump 32. The cold salt pump 23 is connected to the low-temperature molten salt tank 2, driving the molten salt in the low-temperature molten salt tank 2 into the molten salt heater 1 along the feed pipe 11. The hot salt pump 32 is connected to the high-temperature molten salt tank 3, driving the molten salt in the high-temperature molten salt tank 3 into the low-temperature molten salt tank 2. In this embodiment, the molten salt thermal storage unit also includes a steam generator 5, a steam turbine 6, and a first power generation device 7. The steam generator 5 is located between the molten salt outlet of the high-temperature molten salt tank 3 and the molten salt inlet of the low-temperature molten salt tank 2, using cooling water to cool and exchange heat with the high-temperature molten salt discharged from the high-temperature molten salt tank 3. The steam inlet of the steam turbine 6 is connected to the steam outlet of the steam generator 5. During the heat exchange process in the steam generator 5, the steam generated after the cooling water absorbs the high-temperature molten salt enters the steam turbine 6 to perform work. The first power generation device 7 is mechanically connected to the steam turbine 6, and the steam turbine 6 drives the first power generation device 7 to generate electricity.

[0039] The operation of the molten salt thermal storage unit is as follows: When the molten salt thermal storage unit starts operating, the cold salt pump 23 starts and transports the low-temperature or room-temperature molten salt in the low-temperature molten salt tank 2 to the molten salt heater 1 for heating along the feed pipe 11. The heated high-temperature molten salt then continues to enter the high-temperature molten salt tank 3 along the discharge pipe 12. Subsequently, the high-temperature molten salt in the high-temperature molten salt tank 3 is transported to the steam generator 5 by the hot salt pump 32, so that the cooling water in the steam generator 5 exchanges heat with the high-temperature molten salt and is converted into steam. The steam generated by the heat exchange enters the steam turbine 6 to do work, and then the steam turbine 6 drives the first power generation unit 7 to generate electricity. The steam that has completed its work in the steam turbine 6 enters the condenser 101 through the steam outlet of the steam turbine 6, is cooled by the condenser 101, and returns to the steam generator 5 to exchange heat with the high-temperature molten salt. The molten salt that has completed its heat exchange and cooling in the steam generator 5 flows back into the low-temperature molten salt tank 2 along the feed pipe 22.

[0040] In this embodiment, to prevent the high-temperature molten salt formed after heating by the molten salt heater 1 from oxidizing upon contact with air, a protective gas is supplied to the low-temperature molten salt tank 2 and the high-temperature molten salt tank 3 through a protective gas supply unit. This protective gas is an inert gas that does not react with the molten salt. Specifically, nitrogen is used as the protective gas in this embodiment. Since nitrogen is denser than air, the nitrogen entering the low-temperature molten salt tank 2 and the high-temperature molten salt tank 3 will sink and completely cover the surface of the molten salt, isolating it from the air and preventing oxidation and deterioration of the high-temperature molten salt upon contact with air, thereby ensuring the continuous normal operation of the molten salt thermal storage unit.

[0041] refer to Figure 1In this embodiment, the nitrogen supplied by the protective gas supply unit originates from its nitrogen tank 4. Nitrogen is introduced into the molten salt storage tank from the nitrogen tank 4 to isolate the molten salt from the air. During the operation of the molten salt heat storage unit, the molten salt that has completed heat exchange in the steam generator 5 may still retain a small amount of residual heat. To prevent the molten salt entering the low-temperature molten salt tank 2 from oxidizing with air and to further recover the small amount of residual heat at this time, in this embodiment, the nitrogen tank 4 is connected to the low-temperature molten salt tank 2 via a gas supply pipe 42, and the low-temperature molten salt tank 2 is connected to the high-temperature molten salt tank 3 via a ventilation pipe 21. The nitrogen supplied by the nitrogen tank 4 first enters the low-temperature molten salt tank 2 along the gas supply pipe 42 for molten salt protection and residual heat recovery, and then enters the high-temperature molten salt tank 3 from the protective gas outlet of the low-temperature molten salt tank 2 along the ventilation pipe 21 for nitrogen protection. Meanwhile, pressure regulating valves 41 are installed on both the gas supply pipe 42 and the gas supply pipe 21 to regulate the gas pressure of the protective gas released from the nitrogen tank 4 to the low-temperature molten salt tank 2 and the high-temperature molten salt tank 3.

[0042] To avoid wasting protective gas and ensure that it is introduced into the cryogenic molten salt tank 2 and the high-temperature molten salt tank 3 in a reasonable and timely manner for air isolation, and to enable the protective gas residual energy recovery unit to recover the residual energy contained in the protective gas after completing the air isolation task, in this embodiment, the operating status of the protective gas supply unit and the protective gas residual energy recovery unit are interconnected with the operating status of the molten salt thermal storage unit. Specifically, a temperature sensor (not shown in the figure) is installed in the molten salt thermal storage unit to monitor temperature changes. When the molten salt thermal storage unit starts operating, the molten salt heater 1 heats the molten salt, and under the action of the cold salt pump 23 and the hot salt pump 32, the molten salt circulates within the molten salt thermal storage unit. When the temperature sensor detects that the molten salt in the molten salt thermal storage unit begins to release heat and the temperature rises to a threshold, the protective gas supply unit starts operating. Through the automatic control system, the pressure regulating valve 41 is opened, allowing nitrogen from the nitrogen tank 4 to quickly enter the cryogenic molten salt tank 2 and the high-temperature molten salt tank 3, completely covering the molten salt surface to isolate it from air. Nitrogen gas entering the high-temperature molten salt tank 3 is heated upon contact with the molten salt, becoming high-temperature nitrogen gas with high heat. Subsequently, the protective gas residual energy recovery unit begins operation. The high-temperature nitrogen gas discharged from the protective gas outlet of the high-temperature molten salt tank 3 enters the turbine 8, where the turbine converts the thermal energy of the high-temperature nitrogen gas into mechanical energy. To better utilize the mechanical energy converted by the turbine 8, in this embodiment, the protective gas residual energy recovery unit also includes a second power generation device 9. The second power generation device 9 is mechanically connected to the turbine 8, and the turbine 8 drives the second power generation device 9 to generate electricity, thereby converting the mechanical energy into electrical energy for use. After the high-temperature nitrogen gas passes through the turbine 8, most of its residual energy has been converted into mechanical energy, but a small amount of thermal energy remains in the nitrogen gas and is not completely recovered. Therefore, in this embodiment, the protective gas residual energy recovery unit also includes a condenser 101 and an exhaust pipe 102. The condenser 101 is connected to the protective gas outlet of the turbine 8 via an exhaust pipe 81 to recover the residual thermal energy of the protective gas discharged from the turbine 8. The vent pipe 102 is connected to the protective gas outlet of the condenser 101, and the protective gas that has completed the recovery of residual energy is vented through the vent pipe 102.

[0043] refer to Figure 1 The condenser 101 is also connected to the steam outlet of the turbine 6. Steam that has performed work in the turbine 6 can enter the condenser 101 through the steam outlet, be cooled by the condenser 101, and then return to the steam generator 5 to exchange heat with the high-temperature molten salt. To enable the condenser 101 to complete the aforementioned cooling water recirculation process, the condenser 101 included in the protective gas waste energy recovery unit provided in this embodiment can be used in conjunction with the molten salt thermal energy storage unit capable of solar thermal power generation.

[0044] To ensure that the protective gas can pass sequentially through the turbine 8 and condenser 101, and ultimately be smoothly discharged to the outside through the exhaust pipe 102, in this embodiment, the low-pressure end of the protective gas residual energy recovery unit is matched with the low-pressure end of the condenser 101. That is, the gas pressure inside the turbine 8 is higher than the gas pressure inside the condenser 101. The protective gas is driven to the condenser 101 and discharged by utilizing the pressure difference within the protective gas residual energy recovery unit. To achieve a low-pressure environment within the condenser 101 and create a pressure difference between the condenser 101 and the turbine 8, on the one hand, the condenser 101 recovers the residual heat energy of the protective gas, thereby reducing the temperature and pressure of the protective gas within the condenser 101; on the other hand, the protective gas residual energy recovery unit also includes a vacuum pump 103. The vacuum pump 103 is located between the condenser 101 and the exhaust port of the vent pipe 102. It draws the protective gas that has undergone residual heat recovery and cannot be condensed within the condenser 101 to the exhaust port of the vent pipe 102, creating a lower-pressure environment within the condenser 101 compared to the turbine 8. Simultaneously, as the steam discharged from the turbine 6 into the condenser 101 condenses into liquid water and re-enters the steam generator 5, the pressure within the condenser 101 further decreases. This further increases the pressure difference between the condenser 101 and the turbine 8, providing a more robust driving force for the smooth flow of the protective gas within the residual heat recovery unit.

[0045] During the operation of the protective gas residual energy recovery system 100, if the protective gas pressure in the high-temperature molten salt tank 3 and the low-temperature molten salt tank 2 is too high, it may affect the molten salt heat storage and protective gas residual energy recovery performance of the protective gas residual energy recovery system 100, and may even damage the equipment and cause leakage risks. Therefore, in this embodiment, the protective gas supply unit also includes a cold tank pressure sensor 24, a hot tank pressure sensor 33, and an oxygen content sensor (not shown in the figure). Among them, the cold tank pressure sensor 24 is installed on the top of the low-temperature molten salt tank 2 to monitor the gas pressure in the low-temperature molten salt tank 2; the hot tank pressure sensor 33 is installed on the top of the high-temperature molten salt tank 3 to monitor the internal pressure of the high-temperature molten salt tank 3; both the high-temperature molten salt tank 3 and the low-temperature molten salt tank 2 are equipped with oxygen content sensors to monitor the oxygen concentration in the molten salt storage tanks. The pressure regulating valve 41 is communicatively connected to the cold tank pressure sensor 24, the hot tank pressure sensor 33, and the oxygen content sensor. The protective gas supply unit can adjust the valve opening of the pressure regulating valve 41 according to the monitoring values ​​of the cold tank pressure sensor 24, the hot tank pressure sensor 33, and the oxygen content sensor, thereby maintaining the gas pressure in the molten salt storage tank in a stable and controllable state.

[0046] In this embodiment, the specific operation process of the protective gas residual energy recovery unit is as follows: When the molten salt thermal storage unit starts operating and the temperature inside the molten salt thermal storage unit rises to a threshold as monitored by the temperature sensor, the pressure regulating valve 41 in the protective gas residual energy recovery unit opens, allowing nitrogen from the nitrogen tank 4 to be sequentially introduced into the low-temperature molten salt tank 2 and the high-temperature molten salt tank 3. Simultaneously, based on the data feedback from the cold tank pressure sensor 24, the hot tank pressure sensor 33, and the oxygen content sensor regarding the gas composition and pressure in the low-temperature molten salt tank 2 and the high-temperature molten salt tank 3, the control system in the protective gas residual energy recovery unit automatically adjusts the opening of the pressure regulating valve 41. Subsequently, the nitrogen covering the surface of the molten salt in the molten salt tank, while completing the air isolation task, also absorbs some of the heat from the high-temperature molten salt, causing the nitrogen temperature inside the molten salt tank to rise. Then, the high-temperature nitrogen in the molten salt tank is introduced into the turbine 8 of the protective gas residual energy recovery unit, where the turbine 8 converts the thermal energy in the high-temperature nitrogen into mechanical energy. Then, the mechanical energy is converted into electrical energy by the second power generation device 9 connected to the turbine 8 for external use.

[0047] In this embodiment, since the nitrogen gas that has completed the conversion of thermal energy to mechanical energy in the turbine 8 contains a certain amount of residual thermal energy, the nitrogen gas will continue to be transferred from the turbine 8 along the gas passage pipe 81 to the condenser 101 connected to the turbine 8 to fully recover the residual thermal energy. Subsequently, driven by the vacuum pump 103, the nitrogen gas in the condenser 101 is drawn to the exhaust port of the exhaust pipe 102 and finally discharged to the outside or other equipment. Since the nitrogen gas in the condenser 101 that has completed the full recovery of thermal energy has a significantly lower temperature than the high-temperature nitrogen gas in the turbine 8, the gas pressure in the condenser 101 is significantly lower than that in the turbine 8. At the same time, the vacuum pump 103 continuously extracts the nitrogen gas that cannot be condensed in the condenser 101 to the outside, which further reduces the gas pressure in the condenser 101 and further increases the gas pressure difference between the turbine 8 and the condenser 101. The nitrogen gas in the protective gas residual energy recovery unit is driven by the gas pressure difference generated during the above-mentioned residual energy recovery process to pass sequentially through the turbine 8 and the condenser 101, and is finally discharged smoothly to the outside through the exhaust pipe 102. Thus, the protective gas residual energy recovery system 100 provided in this embodiment has fully recovered the residual energy contained in the protective gas that has completed the air isolation task during the molten salt thermal storage process, and the circulation of the protective gas driven by the gas pressure difference further reduces the energy consumption required for the operation of the protective gas residual energy recovery system 100.

[0048] The above are merely preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A protective gas waste energy recovery system based on molten salt thermal storage, characterized in that, include: A molten salt thermal storage unit includes a molten salt heater and a molten salt storage tank, wherein molten salt heated by the molten salt heater is introduced into the molten salt storage tank; A protective gas supply unit supplies protective gas to the molten salt storage tank to isolate the molten salt from contact with air. The protective gas residual energy recovery unit is connected to the protective gas outlet of the molten salt storage tank and receives the protective gas discharged from the molten salt storage tank. The protective gas residual energy recovery unit includes a turbine, and the protective gas entering the protective gas residual energy recovery unit drives the turbine to do work; The protective gas supply unit includes: The pressure regulating valve adjusts the pressure of the protective gas released by the protective gas supply unit; A pressure sensor is connected to the molten salt storage tank. An oxygen content sensor is connected to the molten salt storage tank. The pressure regulating valve is communicatively connected to the pressure sensor and the oxygen content sensor, and adjusts the valve opening according to the monitoring values ​​of the pressure sensor and the oxygen content sensor.

2. The protective gas residual energy recovery system according to claim 1, characterized in that, The molten salt thermal storage unit also includes: A steam generator is connected to the molten salt storage tank to exchange heat with the molten salt in the tank. Steam turbine, in which steam generated by heat exchange in the steam generator enters the steam turbine to do work; The first power generation device is mechanically connected to the steam turbine, and the steam turbine drives the first power generation device to generate electricity.

3. The protective gas residual energy recovery system according to claim 1, characterized in that, The protective gas supplied by the protective gas supply unit is nitrogen.

4. The protective gas residual energy recovery system according to claim 2, characterized in that, The protective gas residual energy recovery unit also includes: The second power generation device is mechanically connected to the turbine, and the turbine drives the second power generation device to generate electricity. A condenser, connected to the protective gas outlet of the turbine, is used to recover the residual heat energy of the protective gas discharged from the turbine.

5. The protective gas residual energy recovery system according to claim 4, characterized in that, The protective gas residual energy recovery unit also includes: The vent pipe is connected to the protective gas outlet of the condenser, and the protective gas that has been recovered for residual energy is vented through the vent pipe.

6. The protective gas residual energy recovery system according to claim 5, characterized in that, The protective gas residual energy recovery unit also includes: A vacuum pump is installed between the condenser and the exhaust port of the vent pipe.

7. The protective gas residual energy recovery system according to claim 1, characterized in that, The molten salt thermal storage unit also includes a temperature sensor to monitor temperature changes in the molten salt thermal storage unit. The starting operating conditions for the protective gas supply unit and the protective gas residual energy recovery unit are: the temperature inside the molten salt thermal storage unit is monitored by the temperature sensor to rise to a threshold value.

8. The protective gas residual energy recovery system according to claim 5, characterized in that, The gas pressure inside the turbine is higher than the gas pressure inside the condenser. The protective gas pressure difference in the protective gas residual energy recovery unit drives the protective gas to the condenser and is discharged through the vent pipe.

9. The protective gas residual energy recovery system according to claim 4, characterized in that, The steam inlet of the condenser is connected to the steam outlet of the steam turbine, and the steam is cooled by the condenser before entering the steam generator.

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