High-voltage induction heating molten salt system and method for energy storage

Abstract

The invention relates to a high-voltage induction heating molten salt system and method for energy storage, and relates to the technical field of heat energy storage, and the system comprises a salt storage tank, an induction heating device, a high-voltage power supply module, a circulating pump and a control system. The induction heating device is arranged on a circulating pipeline inside or outside the salt storage tank, and the high-voltage power supply module is electrically connected with the induction heating device and used for providing high-voltage high-frequency alternating current; the circulating pump is used for driving molten salt to circulate in the system; the control system is connected with the high-voltage power supply module and the circulating pump to adjust heating power and flow velocity. Power is directly supplied to the induction heating device through the high-voltage power supply module, eddy heat is generated in the fused salt or the heating body according to the electromagnetic induction principle, the problems of scaling and local overheating of a traditional resistance heater are solved, high-power and high-efficiency fused salt heating can be achieved, the heat conversion efficiency and operation stability of an energy storage system are improved, and the energy storage system is suitable for large-scale popularization and application. The method is suitable for large-scale wind-light-electricity consumption and industrial heat supply energy storage scenes.

Description

Technical Field

[0001] This invention relates to the field of thermal energy storage technology, and in particular to a high-voltage induction heating molten salt system and method for energy storage. Background Technology

[0002] With the transformation of the global energy structure and the rapid development of renewable energy, the penetration rate of clean energy sources such as wind and solar power in the power grid is constantly increasing. However, these renewable energy sources have significant intermittency and volatility, posing a huge challenge to the supply and demand balance of the power grid. In order to effectively absorb the curtailed wind and solar power and improve the stability and flexibility of the power grid, large-scale energy storage technology has become a hot topic in research and application. Among the many energy storage technologies, molten salt energy storage technology has received widespread attention and application in fields such as solar thermal power generation, power grid peak shaving and frequency regulation, and industrial steam heating due to its advantages such as high energy density, long life, low cost, and environmental friendliness. Liquid molten salts (such as nitrates, carbonates, or chlorides) are usually used as heat transfer and heat storage media, and need to remain liquid at high temperatures to absorb heat energy.

[0003] Currently, electric heating molten salt energy storage systems primarily employ traditional resistance heating technology. Resistance heaters typically consist of a resistance wire and a metal sheath, inserted directly into the molten salt tank or installed within a pipe heater. When energized, the resistance wire heats up, transferring heat to the molten salt through thermal conduction. In practical applications, this traditional resistance heating method suffers from the following limitations: Resistance heaters have limited surface heat load. To achieve high-power heating of tens or even hundreds of megawatts, an extremely large number of heating tubes need to be installed. This not only increases the complexity of the system, but also greatly increases the equipment's footprint and initial investment cost.

[0004] Resistance heaters come into direct contact with high-temperature molten salt. During long-term operation, the molten salt is prone to localized thermal decomposition or crystallization and scaling on the surface of the heating element, leading to a sharp decline in heat transfer efficiency and even causing localized overheating and burnout of the heating element, seriously affecting the safety and service life of the system. Furthermore, traditional electric heating systems typically require a large step-down transformer to reduce the 10kV or 35kV high-voltage power from the grid to a lower voltage (such as 400V or 690V) before supplying power to the resistance heater. This not only increases transformer losses but also reduces overall energy conversion efficiency.

[0005] Logically, based on the existing methods and limitations of electrically heated molten salt, it can be deduced that current resistance heating methods are unable to directly utilize high-voltage electricity for high-power, high-efficiency heating, and suffer from problems such as scaling, localized overheating, short lifespan, and large system size. Therefore, developing a novel molten salt heating system and method that can be directly connected to a high-voltage power grid, avoids scaling failure due to direct contact between the heating element and the molten salt, and achieves high-power, high-efficiency heating has become a major technical problem urgently needing to be solved in this field. Summary of the Invention

[0006] To address the aforementioned issues, this application provides a high-voltage induction heating molten salt system and method for energy storage.

[0007] In a first aspect, this application provides a high-voltage induction heating molten salt system for energy storage, employing the following technical solution: A high-voltage induction heating molten salt system for energy storage includes: a salt storage tank for storing liquid molten salt; an induction heating device including an induction coil and a heating element located within the electromagnetic field of the induction coil, the heating element contacting the liquid molten salt for heat exchange; a high-voltage power supply module electrically connected to the induction coil for providing the induction coil with a high-voltage AC power of 10kV or higher; a circulation pump installed on a pipeline connected to the salt storage tank for driving the flow of liquid molten salt; and a control system communicatively connected to the high-voltage power supply module and the circulation pump for controlling the power supply and the molten salt flow rate.

[0008] By adopting the above technical solution, a high-voltage AC power supply module directly provides the induction coil with a voltage of 10kV or higher. The heating element located within the electromagnetic field's range exchanges heat with the liquid molten salt through contact. On the one hand, it can be directly connected to the high-voltage power grid, eliminating the need for a large step-down transformer, significantly reducing the system's equipment investment cost, floor space, and energy loss during the transformation process, and improving the overall electrothermal conversion efficiency. On the other hand, it achieves complete physical isolation between the high-voltage induction coil and the high-temperature liquid molten salt, completely avoiding the problems of surface crystallization and scaling, local overheating, and even burnout that are easily caused by direct contact between the resistance wire and the molten salt in traditional systems. This significantly improves the system's operational safety and equipment lifespan under high-power heating conditions.

[0009] Preferably, the induction heating device is disposed outside the salt storage tank, the heating element is a tubular structure, the liquid molten salt flows inside the tubular structure, and the induction coil is arranged around the outside of the tubular structure.

[0010] By adopting the above technical solution, the induction coil is completely physically isolated from the molten salt, which not only facilitates the maintenance and repair of the heating device, but also allows the tubular heating element itself to act as a sensing receiver, realizing the instant generation and transfer of heat, which greatly improves the heating efficiency.

[0011] Preferably, the heating element is made of a magnetically conductive and high-temperature resistant alloy material, and a heat-insulating layer is provided between the outer surface of the heating element and the induction coil. The material of the heat-insulating layer is selected from aerogel felt or aluminum silicate ceramic fiber.

[0012] By adopting the above technical solution, the magnetically conductive high-temperature resistant alloy can significantly enhance the eddy current effect and hysteresis loss heating of electromagnetic induction, while the heat insulation layer effectively prevents the high temperature of the heating element from radiating outward and damaging the induction coil, and at the same time avoids the breakdown short circuit between the high voltage coil and the heating element.

[0013] Preferably, the induction heating device is located inside the salt storage tank, the heating element is a porous conductive ceramic structure located at the bottom of the salt storage tank, and the induction coil is sealed in a high-temperature resistant insulating sleeve and inserted into the porous conductive ceramic structure.

[0014] By adopting the above technical solution, in-situ large-area heating can be achieved inside the salt storage tank. The porous ceramic structure provides a huge heat exchange area, making the molten salt in the salt storage tank more uniformly heated and avoiding local solidification.

[0015] Preferably, the high-voltage power supply module includes a high-voltage frequency converter, which converts the power frequency high-voltage electricity into high-frequency high-voltage AC electricity with a frequency of 1kHz-50kHz and outputs it to the induction coil. By adopting the above technical solution, the high-voltage power frequency electricity from the power grid is directly converted into high-frequency high-voltage electricity and delivered to the coil, eliminating the need for a large step-down transformer, reducing transformer losses, and at the same time, the high-frequency current enhances the skin effect, making the heating element heat up more rapidly and concentrated.

[0016] Preferably, the device also includes a temperature sensor, which is located at the molten salt outlet of the induction heating device and electrically connected to the control system. Based on the feedback data from the temperature sensor, the control system uses a PID algorithm to dynamically adjust the output frequency or voltage of the high-voltage power supply module.

[0017] By adopting the above technical solution, precise closed-loop control of molten salt heating temperature is achieved, avoiding decomposition of molten salt due to excessive temperature and ensuring the safe and stable operation of the energy storage system.

[0018] Preferably, the induction coil is made of hollow copper tube, and a cooling medium, such as deionized water or insulating cooling oil, is circulated inside the hollow copper tube.

[0019] By adopting the above technical solution, the Joule heat generated by the high current in the induction coil can be effectively dissipated, preventing the coil temperature from becoming too high and causing insulation aging or melting, thus ensuring that the high-voltage induction heating system can operate continuously at high power for a long time.

[0020] Preferably, the tubular structure is provided with a spiral baffle inside, which is integrally formed or welded to the heating element to enhance the turbulence of the molten salt.

[0021] By adopting the above technical solution, the laminar boundary layer of molten salt inside the tube is destroyed, which greatly improves the convective heat transfer coefficient between the molten salt and the tubular heating element, and further enhances the overall heat exchange efficiency.

[0022] Secondly, this application provides a method for high-voltage induction heating of molten salt for energy storage, comprising the following steps: Step S1: The control system starts the circulation pump, causing the liquid molten salt to flow from the salt storage tank through the heating element of the induction heating device; Step S2: The control system controls the high-voltage power supply module to output high-voltage AC power to the induction coil, generating an alternating magnetic field around the induction coil. Step S3: The heating element generates eddy currents and rapidly heats up under the action of the alternating magnetic field, transferring heat to the flowing liquid molten salt; Step S4: The control system monitors the temperature of the heated molten salt in real time and adjusts the output power of the high-voltage power supply module and the speed of the circulating pump according to the target energy storage temperature.

[0023] By adopting the above technical solution, the control system coordinates the circulating pump and the high-voltage power supply module, and uses an alternating magnetic field to generate eddy currents in the heating element and rapidly raise its temperature, achieving "instant heat generation and transfer" inside the heating element, which greatly improves the heating response speed of the system. At the same time, by monitoring the temperature of the molten salt after heating in real time and dynamically adjusting the output power and the speed of the circulating pump, precise closed-loop control of the molten salt heating process is achieved, effectively avoiding molten salt thermal decomposition caused by excessively high local temperatures and pipe condensation blockage caused by excessively low temperatures, thus ensuring the efficient and stable operation of the thermal storage system.

[0024] Preferably, in step S4, when the molten salt temperature is detected to be lower than the lower limit of the target energy storage temperature, the control system prioritizes increasing the output frequency of the high-voltage power supply module. If the frequency reaches the upper limit but still does not meet the requirements, the speed of the circulating pump is reduced.

[0025] By adopting the above technical solution, when the molten salt temperature is lower than the lower limit of the target energy storage temperature, the control strategy prioritizes increasing the output frequency of the high-voltage power supply module. If the frequency reaches the upper limit and still does not meet the requirements, the speed of the circulating pump is reduced. Since the frequency adjustment of the electrical signal has a millisecond-level ultra-fast response capability, it can respond to temperature fluctuations as quickly as possible without reducing the heat storage throughput of the system. The reduction of the flow rate serves as a physical safety net, effectively extending the heating time of the molten salt in the heating element. This results in extremely high system anti-interference capability and control robustness, ensuring that even under extreme conditions where grid power is limited or the equipment reaches its physical limits, the output molten salt temperature can still strictly meet the energy storage standard requirements.

[0026] In summary, this application includes at least one of the following beneficial technical effects: 1. Because the present invention uses a high-voltage power supply module to directly provide high-voltage AC power to the induction coil, and uses electromagnetic induction to generate eddy currents in the heating element to heat the molten salt, it achieves the effect of directly utilizing high-voltage grid power, eliminating the need for a large step-down transformer, reducing power conversion losses, and realizing high-power, efficient and safe heating.

[0027] 2. In this invention, a tubular magnetic high-temperature resistant alloy heating element is preferably used and the induction coil is placed outside it. Since the heating element is completely physically isolated from the high-temperature molten salt, the problem of easy scaling and local overheating and burnout of traditional resistance wires is completely solved, and the service life of the system is greatly extended. Attached Figure Description

[0028] Figure 1 This is a schematic diagram of a high-voltage induction heating molten salt system for energy storage.

[0029] Figure 2 This is a schematic diagram highlighting the heating element.

[0030] Figure 3 This is another schematic diagram highlighting the heating element.

[0031] Figure 4 This is a schematic diagram of a high-voltage induction heating molten salt system for energy storage.

[0032] Explanation of reference numerals in the attached drawings: 1. Salt storage tank; 2. Induction heating device; 21. Induction coil; 22. Heating element; 23. Thermal insulation layer; 3. High-voltage power supply module; 4. Circulation pump; 5. Control system; 6. Temperature sensor. Detailed Implementation

[0033] The present application will be further described in detail below with reference to all the accompanying drawings.

[0034] This embodiment discloses a high-voltage induction heating molten salt system for energy storage.

[0035] Reference Figure 1 and Figure 2 A high-voltage induction heating molten salt system for energy storage includes a salt storage tank 1, an induction heating device 2, a high-voltage power supply module 3, a circulation pump 4, and a control system 5. The salt storage tank 1 stores liquid molten salt and serves as the core heat carrier and storage container for the entire thermal energy storage system. It can hold a large amount of liquid molten salt (e.g., a mixture of potassium nitrate and sodium nitrate, or a carbonate mixture, or at least two different types of molten salt media for different temperature zones), and is typically covered with a thick insulation layer to reduce heat loss. A main circulation pipeline extends from the bottom or side wall of the salt storage tank 1, and the circulation pump 4 is tightly flanged and installed on this pipeline. The purpose of the circulation pump 4 is to overcome the flow resistance of the system pipeline and provide sufficient pressure head for the flow of liquid molten salt throughout the loop, thereby driving the liquid molten salt to continuously circulate in the pipeline system via forced convection.

[0036] An induction heating device 2 is installed in the pipeline circulation loop. The induction heating device 2 includes an induction coil 21 and a heating element 22. Depending on the actual engineering application scenario, the arrangement position of the induction heating device 2 and the structural form of the heating element 22 can be designed differently. In a preferred embodiment, the induction heating device 2 is located outside the salt storage tank 1, and the heating element 22 is designed as a tubular structure. The two ends of the tubular structure are sealed to the pipeline system through high-temperature resistant flanges, allowing the liquid molten salt pumped by the circulation pump 4 to flow smoothly through the internal cavity of the tubular structure.

[0037] The induction coil 21 is arranged on the outside of the tubular structure in a spiral or multi-layered manner. The heating element 22 is made of a magnetically permeable high-temperature alloy material (such as 310S high-temperature stainless steel, or Inconel 600 nickel-based high-temperature alloy, etc., at least two of which have excellent high-temperature strength and magnetic permeability). This material is selected to maximize the generation of eddy current loss and hysteresis loss in the alternating magnetic field by utilizing its high magnetic permeability and resistivity, thereby achieving its own efficient and rapid heating. To ensure efficient energy utilization and electrical safety, a thermal insulation layer 23 is tightly wrapped between the outer surface of the heating element 22 and the externally surrounding induction coil 21. The thermal insulation layer 23 is made of aerogel felt or aluminum silicate ceramic fiber (both of which have extremely low thermal conductivity and excellent electrical insulation properties). Its function is twofold: firstly, to prevent the high-temperature heat generated by the tubular heating element 22 from radiating outward and dissipating, thus avoiding damage to the surrounding induction coil 21; and secondly, to provide reliable high-voltage electrical insulation, preventing electrical breakdown or arcing short circuit accidents between the high-voltage coil (up to 10kV) and the heating element 22.

[0038] Furthermore, to significantly improve the heat exchange efficiency inside the tubular structure, spiral baffles are specially installed in the internal cavity of the tubular structure. These spiral baffles are manufactured integrally with the inner wall of the heating element 22, or fixedly connected using a high-temperature welding process. The spiral baffles extend spirally along the inner axis of the tube, and their purpose is to forcibly change the laminar flow state of the molten salt inside the tube, causing strong rotation and turbulent mixing. This turbulence effectively breaks down the laminar thermal resistance boundary layer close to the inner wall of the heating tube, allowing the high-temperature molten salt heated at the tube wall to quickly mix with the low-temperature molten salt in the central region of the tube. This significantly enhances the convective heat transfer coefficient between the molten salt and the tubular heating element 22, avoiding overheating caused by localized heat accumulation at the tube wall.

[0039] Reference Figures 1 to 4 Optionally, the induction heating device 2 can also be directly installed inside the salt storage tank 1 to achieve in-situ heating. In this case, the heating element 22 is designed as a porous conductive ceramic structure (such as silicon carbide porous ceramic or barium titanate conductive ceramic, or at least two other conductive ceramic materials) located at the bottom of the salt storage tank 1. The porous structure provides an extremely large specific surface area, which is beneficial for sufficient contact and heat exchange with the surrounding molten salt. Since the induction coil 21 needs to extend into the molten salt, in order to ensure high-voltage insulation and corrosion prevention, the induction coil 21 is tightly sealed in a high-temperature resistant insulating sleeve (such as a high-purity alumina ceramic tube) and is inserted in a mesh or spiral shape within the porous conductive ceramic structure.

[0040] Regardless of the arrangement, the induction coil 21 is electrically connected to the high-voltage power supply module 3. The core function of the high-voltage power supply module 3 is to directly connect to the high-voltage AC power grid and provide the induction coil 21 with high-voltage AC power of 10kV or higher. Specifically, the high-voltage power supply module 3 includes an advanced high-voltage frequency converter assembly. This converter, through a power electronic topology, directly inverts the 50Hz / 60Hz power frequency high-voltage electricity input from the grid into high-frequency high-voltage AC power with a frequency of 1kHz-50kHz, and outputs it to the induction coil 21. The introduction of high-frequency current significantly enhances the skin effect within the heating element 22, making the induced current more concentrated within the thin surface layer of the heating element 22, thereby greatly increasing the equivalent heating resistance and achieving an impressive heating power density. Simultaneously, directly utilizing 10kV high voltage for induction heating completely eliminates the need for the bulky, costly, and no-load loss-prone step-down transformer equipment found in traditional energy storage power stations.

[0041] When the induction coil 21 is subjected to high frequency, high voltage, and high current, its copper conductor will inevitably experience Joule heat loss. To prevent excessive temperature rise and subsequent melting of the insulation layer, the induction coil 21 is made of hollow copper tubing. A flowing cooling medium is continuously introduced into the internal cavity of the hollow copper tubing through an external cooling circulation system. The cooling medium is either deionized water or insulating cooling oil (both media have good specific heat capacity and, after deionization / purification, possess insulating properties), thereby removing the waste heat generated by the coil and ensuring the long-term stable operation of the high-voltage induction heating system.

[0042] To achieve intelligent closed-loop control of the entire system, a control system 5 is installed. The control system 5 is connected to the communication interface of the high-voltage power supply module 3 and the frequency converter driver of the circulating pump 4, and is used to coordinate the power supply and molten salt flow rate of the control system 5. At the liquid molten salt outlet of the induction heating device 2, a high-precision temperature sensor 6 (e.g., a K-type armored thermocouple, or at least two other temperature sensing elements such as a PT100 high-temperature platinum resistance thermometer) is installed on the pipeline. The probe of the temperature sensor 6 penetrates deep into the molten salt fluid, collecting the actual molten salt temperature after heating in real time and converting it into an electrical signal that is fed back to the control system 5. Based on the real-time feedback data from the temperature sensor 6, the microprocessor of the control system 5 calculates the deviation between this data and the preset target energy storage temperature, and uses a PID control algorithm to perform complex data calculations, thereby outputting precise control commands to dynamically adjust the output frequency (or output voltage amplitude) of the high-voltage power supply module 3, and thus precisely control the heating power of the heating element 22, ensuring that the outlet molten salt temperature remains stable within the set process requirements range.

[0043] The implementation principle of Example 1 is as follows: When the energy storage system receives a grid absorption command to start, the control system 5 first activates the circulation pump 4 to establish a stable liquid molten salt flow circulation throughout the pipeline, ensuring that the heating element 22 is filled with flowing molten salt medium. Subsequently, the control system 5 commands the high-voltage power supply module 3 to start, converting the 10kV power frequency high-voltage electricity from the grid into high-frequency high-voltage alternating current and injecting it into the induction coil 21. The high-frequency alternating current instantly generates a powerful high-frequency alternating magnetic field around the coil. This alternating magnetic field penetrates the thermal insulation layer 23 and acts on the internal magnetically conductive high-temperature resistant alloy heating element 22. According to the law of electromagnetic induction, a strong closed-loop eddy current is generated inside the heating element 22. Combined with the hysteresis loss effect, the heating element 22 rapidly generates a massive amount of heat energy in a very short time. This heat energy then passes through the pipe wall through heat conduction and is rapidly absorbed and carried away by the high-speed flowing liquid molten salt inside under the strong turbulence generated by the spiral baffle. During this process, the control system 5 monitors the water temperature in real time through the temperature sensor 6 at the outlet, and uses the PID algorithm to continuously fine-tune the output frequency of the high-voltage frequency converter to increase or decrease the heating power, thereby realizing efficient, safe and accurate direct photothermal conversion and heat storage utilization of high-voltage electrical energy, and completely avoiding the risks of scaling and burning caused by the direct contact of traditional resistance wires with molten salt.

[0044] This application also discloses a method for high-voltage induction heating molten salt for energy storage, which is based on the high-voltage induction heating molten salt system for energy storage described in detail above, and specifically includes the following sequence of coordinated operations: In step S1, at the initial stage of receiving the energy storage heating command, the control system 5 first outputs a low-pressure control signal to start the frequency converter of the circulating pump 4, causing the impeller of the circulating pump 4 to rotate and perform work, drawing liquid molten salt from the salt storage tank 1. Under the action of pump pressure, the liquid molten salt flows stably along the main circulation pipeline through the heating element 22 of the induction heating device 2. At this time, the control system 5 will confirm through the flow meter that a molten salt flow with a rated velocity has been formed in the pipeline to prevent dry burning and no-load during subsequent heating.

[0045] In step S2, after confirming that the molten salt flow is normal, the control system 5 sends a high-voltage enable signal to the high-voltage power supply module 3. The power devices inside the high-voltage power supply module 3, such as the insulated-gate bipolar transistor (IGBT), begin high-frequency switching, outputting a regulated 10kV high-voltage AC current to the induction coil 21 wound around the heating element 22. The high-voltage, high-frequency current flows between the turns of the induction coil 21, generating an alternating magnetic field with intensity varying with time in the space surrounding the induction coil 21 and the heating element 22, according to Ampere's circuital law.

[0046] In step S3, the heating element 22, surrounded by the alternating magnetic field, experiences strong eddy currents formed within its free electrons under the drive of the alternating electromagnetic force. Simultaneously, due to the high permeability of the heating element 22, the magnetic domains generate significant hysteresis losses during repeated flipping. The superposition of eddy current heat and hysteresis heat causes the heating element 22 substrate to heat up rapidly. This generated heat is then efficiently transferred through the inner wall and spiral baffles to the molten salt flowing inside, causing the molten salt temperature to rise rapidly.

[0047] In step S4, during continuous heating operation, the control system 5 enters a real-time closed-loop monitoring state. The control system 5 reads the molten salt temperature data after heating from the temperature sensor 6 installed at the molten salt outlet of the induction heating device 2 in real time. The control system 5 compares this real-time temperature with the target energy storage temperature (e.g., 560℃) set by the host computer, and adjusts the output power of the high-voltage power supply module 3 (mainly through frequency or voltage regulation) and the speed of the circulating pump 4 (to adjust the residence time of the molten salt in the heater) in real time according to the temperature difference.

[0048] Specifically, to address grid power fluctuations or low-temperature conditions under extreme weather conditions, a priority adjustment strategy is set in the control logic of step S4: when the molten salt temperature is detected to be below the target energy storage temperature lower limit (e.g., below 550°C), the control system 5 prioritizes increasing the output frequency of the high-voltage power supply module 3. Because the adjustment response time of the electrical signal frequency is in the millisecond range, it can most quickly increase the heating power without affecting the overall heat storage throughput of the system; if the output frequency of the high-voltage power supply module 3 has reached the physical safety limit of the equipment (e.g., 50kHz) and the molten salt temperature still does not meet the standard, the control system 5 activates secondary adjustment measures, issuing a speed reduction command to the circulating pump 4 to reduce the speed of the circulating pump 4. By slowing down the mass flow rate of the molten salt, the heating time of each unit volume of molten salt inside the heating element 22 is extended, as a backup guarantee to ensure that the temperature of the molten salt finally sent into the salt storage tank 1 strictly meets the energy storage process requirements.

[0049] The above are all preferred embodiments of this application, and are not intended to limit the scope of protection of this application. Therefore, all equivalent changes made in accordance with the structure, shape and principle of this application should be covered within the scope of protection of this application.

Claims

1. A high-voltage induction heating molten salt system for energy storage, characterized in that, include: A salt storage tank (1) is used to store liquid molten salt; an induction heating device (2) includes an induction coil (21) and a heating element (22) located within the electromagnetic field range of the induction coil (21), the heating element (22) being in contact with the liquid molten salt for heat exchange; a high-voltage power supply module (3) is electrically connected to the induction coil (21) and is used to provide the induction coil (21) with a high voltage AC power of greater than or equal to 10kV; a circulation pump (4) is installed on the pipeline connected to the salt storage tank (1) and is used to drive the flow of liquid molten salt; and a control system (5) is communicatively connected to the high-voltage power supply module (3) and the circulation pump (4) respectively and is used to control the power supply and the flow rate of molten salt.

2. The high-voltage induction heating molten salt system for energy storage according to claim 1, characterized in that, The induction heating device (2) is located outside the salt storage tank (1). The heating element (22) is a tubular structure. The liquid molten salt flows through the inside of the tubular structure. The induction coil (21) is arranged around the outside of the tubular structure.

3. The high-voltage induction heating molten salt system for energy storage according to claim 2, characterized in that, The heating element (22) is made of magnetically conductive and high-temperature resistant alloy material. A heat-insulating layer (23) is provided between the outer surface of the heating element (22) and the induction coil (21). The material of the heat-insulating layer (23) is selected from aerogel felt or aluminum silicate ceramic fiber.

4. The high-voltage induction heating molten salt system for energy storage according to claim 1, characterized in that, The induction heating device (2) is located inside the salt storage tank (1). The heating element (22) is a porous conductive ceramic structure located at the bottom of the salt storage tank (1). The induction coil (21) is sealed in a high-temperature resistant insulating sleeve and inserted into the porous conductive ceramic structure.

5. The high-voltage induction heating molten salt system for energy storage according to claim 1, characterized in that, The high-voltage power supply module (3) includes a high-voltage frequency converter, which is used to convert the power frequency high-voltage electricity into high-frequency high-voltage AC electricity with a frequency of 1kHz-50kHz and output it to the induction coil (21).

6. The high-voltage induction heating molten salt system for energy storage according to claim 1, characterized in that, It also includes a temperature sensor (6), which is located at the molten salt outlet of the induction heating device (2) and electrically connected to the control system (5); the control system (5) dynamically adjusts the output frequency or voltage of the high-voltage power supply module (3) based on the feedback data of the temperature sensor (6) using a PID algorithm.

7. The high-voltage induction heating molten salt system for energy storage according to claim 1, characterized in that, The induction coil (21) is made of hollow copper tube and a cooling medium is passed through the hollow copper tube. The cooling medium is deionized water or insulating cooling oil.

8. The high-voltage induction heating molten salt system for energy storage according to claim 2, characterized in that, The tubular structure is provided with a spiral baffle inside, which is integrally formed or welded to the heating element (22) to enhance the turbulence of the molten salt.

9. A method for high-voltage induction heating of molten salt for energy storage, characterized in that, The system implementation based on any one of claims 1-8 includes the following steps: Step S1, the control system (5) starts the circulation pump (4) so ​​that the liquid molten salt flows from the salt storage tank (1) through the heating element (22) of the induction heating device (2); Step S2, the control system (5) controls the high voltage power supply module (3) to output high voltage AC power to the induction coil (21) to generate an alternating magnetic field around the induction coil (21); In step S3, the heating element (22) generates eddy currents and rapidly heats up under the action of the alternating magnetic field, transferring heat to the flowing liquid molten salt; In step S4, the control system (5) monitors the temperature of the heated molten salt in real time and adjusts the output power of the high-voltage power supply module (3) and the speed of the circulating pump (4) according to the target energy storage temperature.

10. The method according to claim 9, characterized in that, In step S4, when the molten salt temperature is detected to be lower than the lower limit of the target energy storage temperature, the control system (5) prioritizes increasing the output frequency of the high-voltage power supply module (3). If the frequency reaches the upper limit but still does not meet the requirements, the speed of the circulating pump (4) is reduced.

Images