Molten salt heat storage system and method

Abstract

The invention provides a fused salt heat storage system and method, and relates to the technical field of fused salt heat storage, and the system comprises a fused salt heating assembly, an energy conversion assembly and a steam generation assembly; the fused salt heating assembly heats low-temperature fused salt to obtain high-temperature fused salt and conveys the high-temperature fused salt to the energy conversion assembly; the energy conversion assembly comprises a fused salt hot tank, a fused salt cold tank and a heat exchange unit, the fused salt hot tank stores high-temperature fused salt, the high-temperature fused salt releases heat in the heat exchange unit to obtain low-temperature fused salt, the low-temperature fused salt is stored in the fused salt cold tank, and the fused salt cold tank conveys the low-temperature fused salt to the fused salt heating assembly; the steam generation assembly comprises a water supply unit, and supplied water output by the water supply unit absorbs heat in the heat exchange unit to obtain superheated steam which is output through the outlet end of the steam generation assembly. The system has high adaptability to power market fluctuation, can participate in power grid peak regulation response while supplying heat, achieves thermoelectric decoupling, improves operation flexibility and has high operation efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of molten salt thermal energy storage, and particularly relates to a molten salt thermal energy storage system and method. Background Art

[0002] With the popularization of the electricity spot market, the price signal guiding mechanism during peak electricity supply and demand periods and peak new energy generation periods is becoming increasingly important. During peak supply and demand, high price signals are used to encourage thermal power enterprises to increase power generation. During peak new energy generation periods, price signals are used to prompt thermal power enterprises to reduce output to optimize the power grid load distribution.

[0003] However, for energy systems such as combined heat and power units that can generate both electricity and heat simultaneously, due to the limitations of heating parameters and heat supply, their peak shaving capacity and peak power generation capacity are limited to a certain extent. This not only leads to trading losses of combined heat and power units in the spot market but also affects the power grid's ability to absorb new energy. Especially during high-demand periods that require rapid response or low-demand periods that require significant output reduction, the inherent limitations of combined heat and power units result in poor adaptability in coping with power demand fluctuations and their inability to effectively participate in power market regulation while providing heat, thus optimizing energy management and scheduling. Summary of the Invention

[0004] In view of the deficiencies of the above-mentioned prior art, the present invention provides a molten salt thermal energy storage system and method, which solve the technical problems that in the prior art, combined heat and power or co-generation systems cannot participate in power market regulation while providing heat, optimize energy management and scheduling, and have poor adaptability in coping with power demand fluctuations.

[0005] On the one hand, the present invention provides a molten salt thermal energy storage system, including a molten salt heating component, an energy conversion component, and a steam generation component;

[0006] The outlet end of the molten salt heating component is connected to the inlet end of the energy conversion component. The molten salt heating component is used to heat low-temperature molten salt to obtain high-temperature molten salt and transport the high-temperature molten salt to the energy conversion component;

[0007] The energy conversion component includes a molten salt hot tank, a molten salt cold tank, and a heat exchange unit. The inlet end of the molten salt hot tank is connected to the outlet end of the molten salt heating component and is used to store high-temperature molten salt. The outlet end of the molten salt hot tank is connected to the inlet end of the molten salt cold tank through the heat exchange unit. The high-temperature molten salt in the molten salt hot tank releases heat in the heat exchange unit to obtain low-temperature molten salt and is stored in the molten salt cold tank. The outlet end of the molten salt cold tank is connected to the inlet end of the molten salt heating component and is used to transport the low-temperature molten salt to the molten salt heating component;

[0008] The steam generation component includes a water supply unit, which is in communication with the heat exchange unit. The feed water output by the water supply unit absorbs heat in the heat exchange unit to obtain superheated steam, and is output through the outlet end of the steam generation component.

[0009] Optionally, the molten salt heating component includes a heat exchange device and an electric heating device, and the heat exchange device is connected in series or in parallel with the electric heating device; when the heat exchange device is connected in series with the electric heating device, the inlet end of the heat exchange device is connected to the outlet end of the molten salt cold tank, the outlet end of the heat exchange device is connected to the inlet end of the electric heating device, and the outlet end of the electric heating device is connected to the inlet end of the molten salt hot tank; when the heat exchange device is connected in parallel with the electric heating device, the inlet end of the heat exchange device and the inlet end of the electric heating device are respectively connected to the outlet end of the molten salt cold tank, and the outlet end of the heat exchange device and the outlet end of the electric heating device are respectively connected to the inlet end of the molten salt hot tank.

[0010] Optionally, the heat exchange device is a steam cooler; the input end of the steam cooler is connected to a cogeneration unit, the output end of the steam cooler is connected to a heat-using end, and the steam cooler is used to heat low-temperature molten salt with the heat re-extracted steam of the cogeneration unit to obtain high-temperature molten salt, and output the heat re-extracted steam after desuperheating treatment to the heat-using end for heat supply.

[0011] Optionally, the heat exchange device is a molten salt heat exchanger; the molten salt heat exchanger is used to heat low-temperature molten salt with a preset heat source to obtain high-temperature molten salt.

[0012] Optionally, the electric heating device is an electric heater; the electric heater is used to electrically heat low-temperature molten salt to obtain high-temperature molten salt.

[0013] Optionally, the heat exchange unit includes a superheater, an evaporator, and a preheater; the outlet end of the molten salt hot tank is sequentially connected to the inlet end of the molten salt cold tank through the superheater, the evaporator, and the preheater.

[0014] Optionally, the steam generation component further includes a feed water pump and a connecting pipeline; the water supply unit is sequentially connected to the preheater, the evaporator, and the superheater through the connecting pipeline, and outputs the superheated steam through the connecting pipeline; the feed water pump is arranged at the outlet end of the water supply unit and is used to pressurize the feed water output by the water supply unit.

[0015] Optionally, the steam generation component further includes a heating unit; the heating unit is arranged at the outlet end of the water supply unit and is used to heat the feed water output by the water supply unit.

[0016] Optionally, the heat exchange unit includes at least one dual-medium heat exchanger; the high-temperature molten salt in the molten salt hot tank releases heat in the first flow channel of the dual-medium heat exchanger to obtain low-temperature molten salt; the feed water output by the feed water unit absorbs heat in the second flow channel of the dual-medium heat exchanger to obtain superheated steam.

[0017] On the other hand, the present invention provides a molten salt heat storage method, which is applied to the molten salt heat storage system described in any one of the above, and the method includes:

[0018] The molten salt heating assembly heats the low-temperature molten salt to obtain high-temperature molten salt, and transports the high-temperature molten salt to the molten salt hot tank for storage;

[0019] The high-temperature molten salt in the molten salt hot tank releases heat in the heat exchange unit to obtain low-temperature molten salt, and is stored in the molten salt cold tank. At the same time, the feed water output by the feed water unit absorbs heat in the heat exchange unit to obtain superheated steam, and is output through the outlet end of the steam generation assembly;

[0020] The low-temperature molten salt in the molten salt cold tank is transported to the molten salt heating assembly.

[0021] The molten salt heat storage system and method provided by the present invention are provided with a molten salt hot tank for storing high-temperature molten salt, which can release heat for power generation when the power demand is high, suspend power generation when the power demand is low, give priority to ensuring heat supply or store heat, and realize the free allocation of energy in the time dimension, so that the system can not only supply heat but also participate in the grid peak shaving response, improving the adaptability of the system to power market fluctuations; the heat exchange unit can use the heat released by the molten salt to heat the feed water to generate steam for power generation, meet the steam demand in industrial production, realize different degrees of heat and power decoupling, enhance the versatility and operation flexibility of the system; the low-temperature molten salt is recovered to the molten salt cold tank and sent back to the heating assembly for recycling, making the system an independent energy cycle system, effectively reducing heat energy loss, improving the overall cycle efficiency, reducing the dependence on external heat sources, and supporting long-term energy storage operation, extending the continuous operation time of the system. The above system has strong adaptability to power market fluctuations, can participate in the grid peak shaving response while supplying heat, realize heat and power decoupling, improve operation flexibility, and has high operation efficiency as an independent energy cycle system.

[0022] Other features and advantages of the present invention will be described in the following specification, and, in part, will be obvious from the specification, or will be understood by implementing the present invention. The objectives and other advantages of the present invention can be realized and obtained by the structures specifically pointed out in the written specification, claims, and drawings.

[0023] The technical solutions of the present invention will be further described in detail below through the drawings and embodiments. Brief Description of the Drawings

[0024] The drawings are used to provide a further understanding of the present invention, and constitute a part of the specification. Together with the embodiments of the present invention, they are used to explain the present invention, and do not constitute a limitation to the present invention. In the drawings:

[0025] Figure 1 is a schematic diagram of the overall structure of a molten salt thermal energy storage system in an embodiment provided by the present application;

[0026] Figure 2 is a schematic diagram of the specific structure of a molten salt thermal energy storage system in another embodiment provided by the present application;

[0027] Figure 3 is a schematic diagram of the process flow of a molten salt thermal energy storage method in an embodiment provided by the present application. Detailed Description of the Embodiments

[0028] The present application will be described in detail below with reference to the drawings and in combination with the embodiments. It should be noted that, without conflict, the embodiments in the present application and the features in the embodiments can be combined with each other.

[0029] In one embodiment, as Figure 1 shown, a molten salt thermal energy storage system is provided, which includes a molten salt heating component, an energy conversion component, and a steam generation component; the outlet end of the molten salt heating component is connected to the inlet end of the energy conversion component, and the molten salt heating component is used to heat low-temperature molten salt to obtain high-temperature molten salt and transport the high-temperature molten salt to the energy conversion component; the energy conversion component includes a molten salt hot tank, a molten salt cold tank, and a heat exchange unit. The inlet end of the molten salt hot tank is connected to the outlet end of the molten salt heating component and is used to store high-temperature molten salt. The outlet end of the molten salt hot tank is connected to the inlet end of the molten salt cold tank through the heat exchange unit. The high-temperature molten salt in the molten salt hot tank releases heat in the heat exchange unit to obtain low-temperature molten salt and is stored in the molten salt cold tank. The outlet end of the molten salt cold tank is connected to the inlet end of the molten salt heating component and is used to transport the low-temperature molten salt to the molten salt heating component; the steam generation component includes a feed water unit, and the feed water unit is communicated with the heat exchange unit. The feed water output by the feed water unit absorbs heat in the heat exchange unit to obtain superheated steam and is output through the outlet end of the steam generation component.

[0030] The molten salt thermal energy storage system provided in this embodiment is provided with a molten salt hot tank for storing high-temperature molten salt, which can release heat for power generation when the power demand is high, suspend power generation when the power demand is low, give priority to ensuring heat supply or store heat, and realize the free allocation of energy in the time dimension, enabling the system to supply heat and participate in grid peak shaving response, improving the system's adaptability to power market fluctuations; the heat exchange unit can use the heat released by the molten salt to heat feed water to generate steam for power generation, meet the steam demand in industrial production, realize different degrees of heat and power decoupling, and enhance the versatility and operation flexibility of the system; the low-temperature molten salt is recycled to the molten salt cold tank and sent back to the heating component for recycling, making the system an independent energy cycle system, effectively reducing heat loss, improving the overall cycle efficiency, reducing the dependence on external heat sources, and supporting long-term energy storage operation, extending the continuous operation time of the system. The above system has strong adaptability to power market fluctuations, can participate in grid peak shaving response while supplying heat, realize heat and power decoupling, improve operation flexibility, and has high operation efficiency as an independent energy cycle system.

[0031] Among them, the molten salt applied in this application is a binary salt, that is, a mixture composed of two different types of salts, usually a mixture of two different nitrates or nitrites, such as sodium nitrate (NaNO3) and potassium nitrate (KNO3), which form a eutectic mixture after being mixed in a certain proportion.

[0032] In one embodiment, the molten salt heating component includes a heat exchange device and an electric heating device, and the heat exchange device and the electric heating device are connected in series or in parallel; when the heat exchange device and the electric heating device are connected in series, the inlet end of the heat exchange device is connected to the outlet end of the molten salt cold tank, the outlet end of the heat exchange device is connected to the inlet end of the electric heating device, and the outlet end of the electric heating device is connected to the inlet end of the molten salt hot tank; when the heat exchange device and the electric heating device are connected in parallel, the inlet ends of the heat exchange device and the electric heating device are respectively connected to the outlet end of the molten salt cold tank, and the outlet ends of the heat exchange device and the electric heating device are respectively connected to the inlet end of the molten salt hot tank.

[0033] In this embodiment, the molten salt heating component is specifically provided with two different forms of heating devices, namely a heat exchange device and an electric heating device, and the connection form of the two heating devices is not fixed, and can adopt a series or parallel connection method. In the series mode, electric heating is used as a supplementary means to ensure that even when the heat exchange device is not sufficient to heat the molten salt to the target temperature, the required high-temperature state can still be achieved. In the parallel mode, a redundancy mechanism is provided. When one heating device fails or is limited, the other heating device can continue to work to ensure the continuous and stable operation of the system, enhancing the system's ability to cope with various working conditions. Finally, the two heating devices work together to heat the low-temperature molten salt to the target temperature, obtain high-temperature molten salt and store it in the molten salt hot tank.

[0034] In one embodiment, as Figure 2 shown, the heat exchange device is a steam cooler; the input end of the steam cooler is connected to the combined heat and power unit, and the output end of the steam cooler is connected to the heat-using end. The steam cooler is used to heat the low-temperature molten salt with the thermal re-extracted steam of the combined heat and power unit to obtain high-temperature molten salt, and output the thermal re-extracted steam after desuperheating treatment to the heat-using end for heat supply.

[0035] Specifically, the steam cooler not only needs to cool the steam, but also needs to use the waste heat of the steam for heating. During the operation of the molten salt combined heat and power unit, a part of the high-temperature and high-pressure thermal re-extracted steam will be extracted. The thermal re-extracted steam passes through the inside of the steam cooler. Part of the heat of the thermal re-extracted steam is used to heat the molten salt, resulting in a temperature drop. Although the temperature of the thermal re-extracted steam decreases, the steam with a relatively high calorific value will be transported to the downstream heat-using end, such as industrial users, district heating systems, etc., and continue to be used for heat supply; the high-temperature molten salt heated by using the heat of the thermal re-extracted steam needs to be further heated or stored in the molten salt heat tank.

[0036] In this embodiment, the steam cooler recovers the steam waste heat that might otherwise be wasted to heat the molten salt, realizing waste heat reuse, avoiding energy loss, and at the same time, the steam after desuperheating treatment can still be used for heat supply, forming a multi-stage energy utilization chain, significantly improving the thermal efficiency of the overall system; compared with simply relying on external fuel heating, the method of using the steam cooler to heat the low-temperature molten salt is more energy-saving and environmentally friendly, which helps to build a closed-loop molten salt circulation system and ensure the continuous supply of high-temperature molten salt.

[0037] In one embodiment, the heat exchange device is a molten salt heat exchanger; the molten salt heat exchanger is used to heat the low-temperature molten salt with a preset heat source to obtain high-temperature molten salt.

[0038] Specifically, the molten salt heat exchanger uses molten salt as the heat transfer medium. Molten salt itself has good thermal stability and a relatively high heat capacity, and is widely used in processes that require high-temperature operation. When the low-temperature molten salt flows through the molten salt heat exchanger, it exchanges heat with the externally preset heat source and absorbs heat to become high-temperature molten salt after temperature rise.

[0039] In this embodiment, the molten salt heat exchanger can adapt to different forms of heat sources, enhancing the adaptability and application range of the system, especially suitable for clean energy access scenarios, and the structure of the molten salt heat exchanger is mature and the operation is stable, suitable for long-term operation in high-temperature and high-pressure environments.

[0040] In one embodiment, the electric heating device is an electric heater; the electric heater is used to electrically heat the low-temperature molten salt to obtain high-temperature molten salt.

[0041] In this embodiment, the electric heater has a fast response speed, can provide very precise temperature control, and ensure that the molten salt can reach the required high temperature state. When there are multiple clean energy supply options, the electric heater can access clean energy through the power grid, increasing the flexibility and sustainability of the system, making the operation more stable and reliable, and reducing the maintenance requirements and failure risks.

[0042] Furthermore, the heat exchange unit includes a superheater, an evaporator, and a preheater; the outlet end of the molten salt hot tank is sequentially connected to the inlet end of the molten salt cold tank through the superheater, the evaporator, and the preheater.

[0043] Furthermore, the steam generation assembly further includes a feed water pump and connecting pipelines; the feed water unit is sequentially connected to the preheater, the evaporator, and the superheater through the connecting pipelines, and outputs superheated steam through the connecting pipelines; the feed water pump is arranged at the outlet end of the feed water unit and is used to pressurize the feed water output by the feed water unit.

[0044] In this embodiment, the high-temperature molten salt discharged from the molten salt hot tank needs to release heat through the heat exchange unit. At the same time, the feed water output by the feed water unit needs to flow through the heat exchange unit to absorb heat and generate superheated steam.

[0045] In one implementation manner, the heat exchange unit specifically includes a superheater, an evaporator, and a preheater connected in sequence. Among them, for the process of the high-temperature molten salt releasing heat, the main function of the superheater is to further heat the medium that has been converted into saturated steam so that its temperature exceeds the boiling point and becomes superheated steam. After the high-temperature molten salt flows out of the molten salt hot tank, it first passes through the superheater, releases heat to the working medium that has been converted into saturated steam, and heats it to the superheated state to obtain superheated steam; the evaporator is responsible for completely converting the preheated feed water into saturated steam. During this process, the liquid absorbs enough heat to reach its boiling point and turns into a gas state. After the superheater, the high-temperature molten salt enters the evaporator and continues to release heat to the preheated feed water, causing the feed water to boil and be converted into saturated steam; the function of the preheater is to preliminarily heat the feed water, increase its temperature but not make it boil, which helps to reduce the working load of the subsequent evaporator and improve the thermal efficiency of the overall system. After passing through the superheater and the evaporator, the temperature of the high-temperature molten salt drops but still remains at a relatively high level. At this time, it enters the preheater to preheat the feed water that is about to enter the evaporator. The temperature of the preheated feed water is close to the boiling point, preparing for the subsequent evaporation process; for the process of the feed water absorbing heat, the feed water first enters the preheater, absorbs heat and approaches the saturated temperature, then enters the evaporator, absorbs more heat and changes from the liquid state to the saturated steam state, and finally enters the superheater, where the steam continues to absorb heat and increases in temperature to become high-temperature and high-pressure superheated steam.

[0046] Among them, the preheated feed water is pressurized by a feed water pump to ensure that it can smoothly enter and flow through the entire steam generation path. The feed water pump not only provides the necessary pressure to push the water forward, but also can precisely control the water volume entering each heat exchange device to maintain the balance and stability of the system. In this application, the specific installation position of the feed water pump is not limited. For example, Figure 2 As shown, it can be specifically set at the evaporator. To ensure that the feed water can smoothly enter the evaporator and undergo the evaporation process at high efficiency, it is necessary to pressurize the feed water through a water pump, which helps to overcome the pipeline resistance and ensure that the feed water enters the evaporator at an appropriate pressure.

[0047] In one embodiment, the steam generation assembly further includes a heating unit; the heating unit is arranged at the outlet end of the feed water unit and is used to heat the feed water output by the feed water unit.

[0048] In this embodiment, before the feed water enters the preheater, the heating unit is used to preheat the feed water from the coal-fired power generation unit or the chemically treated feed water to 240°C to 270°C in advance. By preheating the feed water to a higher temperature in advance, the heat input required by subsequent devices such as the preheater and the evaporator can be significantly reduced, reducing the working burden of the system and improving the thermal efficiency of the entire system; moreover, the sudden entry of the un-preheated low-temperature feed water into the heat exchange unit may cause overheating in local areas, posing a potential threat to the equipment. Preheating in advance can ensure that the equipment works under more uniform conditions, extend the service life and improve the stability of the system.

[0049] In one embodiment, the heat exchange unit includes at least one dual-medium heat exchanger; the high-temperature molten salt in the molten salt hot tank releases heat in the first flow channel of the dual-medium heat exchanger to obtain low-temperature molten salt; the feed water output by the feed water unit absorbs heat in the second flow channel of the dual-medium heat exchanger to obtain superheated steam.

[0050] Specifically, the dual-medium heat exchanger is a heat exchange device with two independent flow channels, which are respectively used for the flow of two different media. The first flow channel is fed with high-temperature molten salt from the molten salt hot tank, releases heat during the process of flowing through the heat exchanger, and becomes low-temperature molten salt after the temperature drops, and finally flows into the molten salt cold tank; the second flow channel is fed with the feed water from the feed water unit, absorbs the heat released by the high-temperature molten salt during the process of flowing through the heat exchanger, gradually heats up and is converted into superheated steam. The two media conduct indirect contact heat exchange through the heat transfer wall surface inside the heat exchanger.

[0051] In this embodiment, the dual-medium heat exchanger completes the heat exchange of two media within one device, replacing the functions of multiple heat exchange devices in the traditional system, reducing the number of devices and floor area, facilitating the modular design of the system. Moreover, since the molten salt and feed water conduct heat exchange within the same heat exchanger, the heat transfer path is short and the heat exchange area is large, which helps to improve the overall heat exchange efficiency. Furthermore, the heating curve of the feed water in the second flow channel can be optimized according to the temperature distribution of the molten salt to achieve more efficient energy transfer. And compared with the traditional series connection method of multiple-stage heat exchangers, using the dual-medium heat exchanger can reduce the pipeline connections, the number of valves and the complexity of the control system, lower the maintenance difficulty and failure rate, and improve the stability and reliability of the system operation.

[0052] Furthermore, the outlet end of the steam generation assembly is connected to the steam turbine, used to output superheated steam to the steam turbine for power generation.

[0053] Wherein, the steam turbine is a condensing steam turbine or a back-pressure steam turbine.

[0054] In this embodiment, the condensing steam turbine usually operates under high pressure and high temperature conditions, can achieve a relatively high thermoelectric conversion efficiency, and can completely convert the exhausted steam into water through the condenser, recovering more latent heat and further improving the overall energy efficiency of the system, which is especially suitable for scenarios with a large demand for power supply. While the back-pressure steam turbine is not equipped with a condenser, the exhausted steam still maintains a certain pressure and temperature, which can be directly used for heating or other industrial processes, thus realizing cogeneration of heat and power, improving the overall utilization rate of energy. And for applications with both power and heat load requirements, the back-pressure steam turbine can flexibly adjust the ratio of power generation to heat supply according to actual needs to achieve the best energy distribution.

[0055] The molten salt thermal energy storage system provided by this application is as Figure 2 shown, and its specific working process is as follows:

[0056] First, extract hot reheat steam (about 1.5 MPa - 5 MPa, 530 °C - 600 °C) from the cogeneration unit, and then use the heat exchange device to conduct heat exchange between the hot reheat steam and the low-temperature molten salt. The heat exchange device is specifically a steam-cooled heat exchanger. After the low-temperature molten salt absorbs heat, its temperature rises, while the pressure of the hot reheat steam remains unchanged and the temperature drops to about 300 °C - 450 °C and then continues to supply heat to the heat-consuming end. This process replaces the traditional desuperheater and pressure reducer, improving the energy utilization efficiency;

[0057] Secondly, use the heat exchange device, specifically an electric heater, to further heat the high-temperature molten salt. The power supply of the electric heater can be new energy power, off-peak power or plant power. And the electric heater and the steam-cooled heat exchanger can also be connected in parallel to jointly heat. The high-temperature molten salt after steam-coupled electric heating is transported to the molten salt hot tank, and the temperature of the molten salt hot tank is about 520 °C - 550 °C;

[0058] After that, the high-temperature molten salt in the molten salt hot storage tank releases heat through the heat exchange unit to reduce its temperature, and is stored in the molten salt cold storage tank. The temperature of the molten salt cold storage tank is about 275°C to 315°C, while the feed water from the coal-fired power unit or the chemically treated feed water is preheated to 240°C to 270°C. The preheated feed water is successively sent to the preheater, evaporator, and superheater by the feed water pump, absorbing the heat released by the high-temperature molten salt, and finally generating superheated steam at high temperature and pressure (16.7 MPa, 538°C). The superheated steam is sent to the main steam inlet of the cogeneration unit, increasing the power generation capacity of the unit;

[0059] Finally, the superheated steam at high temperature and pressure generated by the heat release of the molten salt enters the condensing or back-pressure steam turbine to do work and generate electricity.

[0060] The above molten salt thermal energy storage system is put into production and use, and the specific operation data is as follows: During the molten salt heat storage process, the main steam parameters of the cogeneration unit are 16.7 MPa and 538°C. The extracted hot reheat steam parameters are 2.2 MPa, 538°C, and 250 t / h. After heat exchange through the heat exchange device, the temperature drops to 390°C and is supplied externally. Among them, the heat storage power of the heat exchange device is about 22.8 MW, and the heat storage power of the coupled electric heating molten salt is 2.1 MW. The obtained high-temperature molten salt is stored in the molten salt hot storage tank. The temperature of the molten salt hot storage tank is 548°C, the temperature of the molten salt cold storage tank is 305°C, and the molten salt flow rate is 237.6 t / h;

[0061] During the molten salt heat release process, 350.2 t / h of high-temperature molten salt flows out of the molten salt hot storage tank, successively passes through the preheater, evaporator, and superheater, heating the feed water with parameters of 17 MPa, 260°C, and 56 t / h output from the feed water unit to superheated steam at 16.7 MPa and 538°C, and sending it to the main steam inlet of the cogeneration unit, increasing the power generation capacity of the unit. After calculation and analysis, the comprehensive efficiency of the molten salt thermal energy storage system provided by this application is 43.1%.

[0062] In one embodiment, as Figure 3 shown, a molten salt heat storage method is provided. This method can be applied to the molten salt heat storage system in any of the above embodiments. Among them, the execution subject of this method can be a signal detection device, a computer device, etc. This method includes the following steps: The molten salt heating component heats the low-temperature molten salt to obtain high-temperature molten salt, and transports the high-temperature molten salt to the molten salt hot storage tank for storage; The high-temperature molten salt in the molten salt hot storage tank releases heat in the heat exchange unit to obtain low-temperature molten salt, and is stored in the molten salt cold storage tank. At the same time, the feed water output by the feed water unit absorbs heat in the heat exchange unit to obtain superheated steam, and is output through the outlet end of the steam generation component; The low-temperature molten salt in the molten salt cold storage tank is transported to the molten salt heating component.

[0063] In the above method, the molten salt thermal storage tank can store a large amount of thermal energy, enabling the system to release heat for power generation during peak power demand and store heat during valleys, enhancing the support capacity for power grid regulation; the feed water passes through the preheating, evaporation, and superheating stages in sequence in the heat exchange unit, achieving cascaded utilization of heat and improving the overall thermal efficiency; the system can be used for power generation and can also adjust the heat supply as needed, enhancing operational flexibility; the molten salt has good thermal stability and can provide a stable heat source; the setting of the hot and cold molten salt tanks provides a buffer space for the system, ensuring continuous and safe operation of the system.

[0064] The technical features of the above embodiments can be combined arbitrarily. For the sake of brevity of description, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, it should be considered as falling within the scope described in this specification.

[0065] The above embodiments only represent several implementation modes of the present application. The description is relatively specific and detailed, but it should not be construed as a limitation on the patent scope of the present application. It should be noted that for those of ordinary skill in the art, without departing from the concept of the present application, several modifications and improvements can still be made, and these all belong to the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the appended claims.

Claims

1. A molten salt thermal energy storage system, characterized in that, It includes a molten salt heating component, an energy conversion component, and a steam generation component; The outlet end of the molten salt heating component is connected to the inlet end of the energy conversion component. The molten salt heating component is used to heat low-temperature molten salt to obtain high-temperature molten salt and transport the high-temperature molten salt to the energy conversion component; The energy conversion component includes a molten salt hot tank, a molten salt cold tank, and a heat exchange unit. The inlet end of the molten salt hot tank is connected to the outlet end of the molten salt heating component and is used to store high-temperature molten salt. The outlet end of the molten salt hot tank is connected to the inlet end of the molten salt cold tank through the heat exchange unit. The high-temperature molten salt in the molten salt hot tank releases heat in the heat exchange unit to obtain low-temperature molten salt and is stored in the molten salt cold tank. The outlet end of the molten salt cold tank is connected to the inlet end of the molten salt heating component and is used to transport the low-temperature molten salt to the molten salt heating component; The steam generation component includes a feed water unit. The feed water unit is in communication with the heat exchange unit. The feed water output by the feed water unit absorbs heat in the heat exchange unit to obtain superheated steam and is output through the outlet end of the steam generation component.

2. The molten salt thermal energy storage system according to claim 1, characterized in that The molten salt heating component includes a heat exchange device and an electric heating device. The heat exchange device is connected in series or in parallel with the electric heating device; When the heat exchange device is connected in series with the electric heating device, the inlet end of the heat exchange device is connected to the outlet end of the molten salt cold tank, the outlet end of the heat exchange device is connected to the inlet end of the electric heating device, and the outlet end of the electric heating device is connected to the inlet end of the molten salt hot tank; When the heat exchange device is connected in parallel with the electric heating device, the inlet end of the heat exchange device and the inlet end of the electric heating device are respectively connected to the outlet end of the molten salt cold tank, and the outlet end of the heat exchange device and the outlet end of the electric heating device are respectively connected to the inlet end of the molten salt hot tank.

3. The molten salt thermal energy storage system according to claim 2, wherein The heat exchange device is a steam cooler; The input end of the steam cooler is connected to a cogeneration unit, and the output end of the steam cooler is connected to a heat-using end. The steam cooler is used to heat low-temperature molten salt with the thermal re-extracted steam of the cogeneration unit to obtain high-temperature molten salt and output the temperature-reduced thermal re-extracted steam to the heat-using end for heat supply.

4. The molten salt thermal energy storage system according to claim 2, characterized in that The heat exchange device is a molten salt heat exchanger; The molten salt heat exchanger is used to heat low-temperature molten salt with a preset heat source to obtain high-temperature molten salt.

5. The molten salt thermal energy storage system according to claim 2, wherein, The electric heating device is an electric heater; The electric heater is used to electrically heat low-temperature molten salt to obtain high-temperature molten salt.

6. The molten salt thermal energy storage system according to claim 1, wherein, The heat exchange unit includes a superheater, an evaporator, and a preheater; The outlet end of the molten salt hot tank is sequentially connected to the inlet end of the molten salt cold tank through the superheater, the evaporator, and the preheater.

7. The molten salt thermal energy storage system according to claim 6, wherein The steam generation component further includes a feed water pump and a connecting pipeline; The feed water unit is sequentially connected to the preheater, the evaporator, and the superheater through the connecting pipeline and outputs the superheated steam through the connecting pipeline; The feed water pump is arranged at the outlet end of the feed water unit and is used to pressurize the feed water output by the feed water unit.

8. The molten salt thermal energy storage system according to claim 1 or 7, characterized in that, The steam generation component further includes a heating unit; The heating unit is arranged at the outlet end of the feed water unit and is used to heat the feed water output by the feed water unit.

9. The molten salt thermal energy storage system according to claim 1, wherein The heat exchange unit includes at least one dual-medium heat exchanger; The high-temperature molten salt in the molten salt hot tank releases heat in the first flow channel of the dual-medium heat exchanger to obtain low-temperature molten salt; The feed water output by the feed water unit absorbs heat in the second flow channel of the dual-medium heat exchanger to obtain superheated steam.

10. A molten salt heat storage method, characterized in that, The method is applied to the molten salt thermal energy storage system according to any one of claims 1 to 9, and the method includes: The molten salt heating assembly heats the low-temperature molten salt to obtain high-temperature molten salt and transports the high-temperature molten salt to the molten salt hot tank for storage; The high-temperature molten salt in the molten salt hot tank releases heat in the heat exchange unit to obtain low-temperature molten salt and stores it in the molten salt cold tank. At the same time, the feed water output by the feed water unit absorbs heat in the heat exchange unit to obtain superheated steam and is output through the outlet end of the steam generation assembly; The low-temperature molten salt in the molten salt cold tank is transported to the molten salt heating assembly.

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