Experimental system and method for researching thermal-electric-flow field coupling effect of molten salt electrolytic cell

Abstract

The invention belongs to the technical field of molten salt electrolysis in metal smelting, and particularly relates to an experimental system and method for researching the thermal-electric-flow field coupling effect of a molten salt electrolytic bath. The experimental system is composed of a C-shaped electrolytic bath and a monitoring system. The anode is a core component, a cavity is arranged in the anode close to the side wall and the bottom, and a plurality of independently controlled carbon silicon rods are arranged in the cavity to provide heat for the anode; a plurality of longitudinal through holes are formed in the anode, when electrolyte needs to be stirred, the upper ends of the through holes are connected with a gas source, gas absorbs heat when passing through the interior of the anode, the temperature rises, then the gas enters an electrolyte melt to drive the electrolyte to flow, and the effect that the electrolyte is stirred by the gas is achieved; when the electrolyte does not need to be stirred, the through holes are used for anode gas escape. The monitoring system can accurately measure various parameters such as heat source power, temperature, heat flux and the like, and can control the heating device. And a reliable experimental basis is provided for industrial tank numerical model verification and optimization, heat balance optimization and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of molten salt electrolysis in metal smelting, and in particular relates to an experimental system and method for studying the thermal-electrical-current field coupling effect of a molten salt electrolytic cell. Background Art

[0002] Light metals and some rare earth metals are typically produced using molten salt electrolysis. For aluminum, for example, the largest electrolysis unit currently operates at 620 kA, with operating temperatures ranging from 940°C to 980°C. It uses a high-temperature cryolite-alumina melt as the electrolyte, hot molten aluminum as the liquid cathode, and a carbonaceous material as the anode. The strong direct current generates strong electromagnetic forces within the molten metal, causing the fluids within the electrolytic cell—including the molten aluminum and liquid electrolyte—to flow rapidly. This forces the hot, highly corrosive fluids within the cell to impact the cell's refractory materials, accelerating cell damage. To extend the life of the electrolytic cell, heat is dissipated from the outer cell walls to promote the formation of a solid electrolyte layer on the inner wall, protecting the refractory from corrosion by the high-temperature fluids. The electromagnetic, temperature, and flow fields within the electrolytic cell significantly influence its design, operation, and production efficiency. A deeper understanding of the coupling mechanisms between these physical fields is crucial for these fields, enabling the design of more advanced electrolytic cells and the development of more efficient technologies. However, the operating temperature of the molten salt electrolyzer is high, the system is highly complex, and the research system involves high temperature, high corrosion, and high magnetic field, making the research difficult.

[0003] To date, research on the multi-physics field of molten salt electrolyzers has been limited to a few methods, including low-temperature water model substitution, finite element numerical simulation, and industrial electrolyzer physical field testing. The physical field characteristics and behavior of low-temperature water models differ significantly from those of high-temperature molten salt electrolyzers, resulting in significant limitations in the results obtained. For example, patent CN202010464370.6 proposes a flow field visualization method based on a water model. However, due to significant differences in physical properties (density, viscosity, conductivity, etc.) compared to high-temperature molten salt systems, it is unable to replicate the actual thermal-electrical-fluid field coupling behavior, resulting in low reliability of experimental results. Finite element numerical simulation is limited by computing power and a lack of valid data, and the results obtained lack universality. For example, key parameters such as latent heat of phase change and dynamic changes in electrolyte molecular ratios are difficult to accurately model, resulting in large deviations between simulation results and actual results. The parameter determination method proposed in patent CN202211529858.8 is sensitive to initial values ​​and does not consider the buffering effect of latent heat of phase change on thermal equilibrium, limiting its universality. Industrial electrolytic cell testing can only test the behavior of a certain period of time, the adjustment range of the electrolytic cell state is small, and the testing cost is very high. Traditional devices mostly use a single temperature zone heating, which cannot accurately simulate the non-uniform temperature distribution of the industrial tank. Although the simulation system of patent CN202011548690.6 has a complex structure, the temperature control range is narrow (±10°C), which is difficult to match the actual working conditions. The existing technology has sparse sampling points, high costs and high risks. It is difficult to systematically study non-steady-state processes (such as sudden load changes and dynamic evolution of the furnace side), and it is difficult to capture the microscopic temperature gradient of the solid-liquid interface and the dynamic changes in the thickness of the furnace side, which restricts the analysis of the multi-physical field coupling mechanism.

[0004] Existing methods have significant shortcomings in high-temperature stability, multi-field coupling simulation accuracy, data acquisition density and cost control. There is an urgent need for a laboratory-scale high-fidelity simulation system that can reproduce the non-steady-state process of industrial electrolyzers while taking into account safety, flexibility and economy. Summary of the Invention

[0005] To address these challenges, we have designed a laboratory-scale anode slice physical model. Through structural innovation, high-density sampling, and equivalent material substitution, we enable high-precision, low-cost research into the multi-physics coupling mechanisms of thermal, electrical, and current in molten salt electrolyzers, providing a reliable experimental platform for industrial cell optimization. This allows us to simulate the operating conditions of industrial electrolyzers, allowing for cost-effective investigation of the coupling mechanisms between the various physical fields within molten salt electrolyzers and establishing an effective database for large-scale numerical simulations.

[0006] The present invention provides an experimental system for studying the thermal-electrical-fluid field coupling effect of a molten salt electrolyzer, which consists of a C-type electrolyzer and a monitoring system.

[0007] The C-type electrolytic cell mainly includes an outer shell, an insulation layer, a heating layer, a crucible, a heat exchanger, an anode, an anode lifting device, an electrolyte, molten aluminum, and a furnace side. The crucible is a trough with a slope on one side. Several thermocouples are installed inside the crucible. The heating layer is coated on the side walls and bottom of the crucible. The heating layer has a hollow structure and is equipped with several independently controlled heating units on the side walls and bottom. Each heating unit is equipped with several carbon silicon rods, which are connected to a power supply. The insulation layer is coated on the side walls and bottom of the heating layer, and the outer shell is coated on the side walls and bottom of the insulation layer. The heat exchanger is located on the outer shell of the crucible with a slope and is connected to an air compressor to cool the outer shell. The electrolyte and molten aluminum are located in the crucible, with the electrolyte at the top and the molten aluminum at the bottom. The furnace side is naturally generated on the side walls of the crucible during the electrolysis process.

[0008] The anode is immersed in the electrolyte, and its position is changed by an anode lifting device. A cavity is provided inside the anode near the side wall and bottom, and a number of individually controlled carbon silicon rods are placed in the cavity, and the carbon silicon rods are connected to a power supply. The anode is provided with a number of longitudinal through holes. When the electrolyte needs to be stirred, the upper end of the through hole is connected to the gas source. When the electrolyte does not need to be stirred, the upper end of the through hole is exposed to the atmosphere or connected to a gas recovery device.

[0009] The shell is made of steel; the insulation layer is made of silicon nitride and silicon carbide refractory bricks; the crucible is made of graphite; the anode is made of graphite;

[0010] The monitoring system includes a computer, a data acquisition card, a multi-channel heat flux meter module, a thermocouple temperature module, a gas flow meter module, and a heating module; among them, the multi-channel heat flux meter module records the heat flux density data around the heat exchanger, the thermocouple temperature module records the temperature data of thermocouples located at different positions of the crucible, the gas flow meter module records the gas flow data when the upper end of the anode through-hole is connected to the gas source, the heating module records and controls the parameters of the carbon silicon rod in the anode and the heating unit in the heating layer, and the data acquisition card converts the analog quantities recorded by each module into digital quantities, and uses a computer for real-time online monitoring or intermittent measurement.

[0011] The experimental method for studying the thermal-electric-current field coupling effect of a molten salt electrolytic cell described in the present invention includes the following contents: when the molten salt electrolytic cell experiment is carried out using the above-mentioned experimental system, it is divided into a high-temperature zone and a low-temperature zone, wherein: the high-temperature zone corresponds to the inter-electrode area between the anode and the aluminum liquid in the electrolytic cell, which is equivalent to the high current density area between the traditional anode and cathode, and the resistance heat concentration effect in the industrial cell is simulated by the heating layer, and the temperature range is 940℃-980℃; the low-temperature zone corresponds to the leg extension area of ​​the furnace side of the crucible belt slope in the electrolytic cell, and the side wall forced heat dissipation mechanism is simulated by the heat exchanger to promote the generation and maintenance of the solid electrolyte layer (mainly the furnace side formed by the sloped side of the crucible belt with the heat exchanger installed), and the temperature range is 880℃-920℃; through regional temperature control and dynamic power adjustment, the non-uniform temperature field distribution and the dynamic evolution process of the furnace side of the industrial electrolytic cell are reproduced.

[0012] For different stages of the electrolysis process, the monitoring system records the temperature information transmitted by thermocouples at different positions in the crucible in real time and dynamically monitors the temperature. At the same time, the monitoring system adjusts the power of the heating unit in the heating layer and the power of the carbon silicon rod in the anode according to the real-time temperature information, controls the heating of the crucible and the anode, and achieves the purpose of controlling electrolysis. It simulates the non-uniform temperature distribution caused by the current change of the industrial cell, as well as the steady-state and non-steady-state processes of the industrial cell at different electrolysis stages.

[0013] When the electrolyte needs to be stirred, the upper end of the anode through-hole is connected to a gas source, which is an inert gas or air. The gas flow is regulated by a monitoring system. The gas absorbs heat when passing through the anode with a carbon silicon rod (heating device) inside. After the temperature rises, it enters the electrolyte melt to drive the electrolyte flow, achieving the effect of gas stirring the electrolyte. When the electrolyte does not need to be stirred, the anode through-hole is used for the anode gas to escape.

[0014] The monitoring system measures various data during the experiment and controls the power of the heating device. The composition of the electrolyte and the quality of the liquid electrolyte can be accurately measured.

[0015] Furthermore, the monitoring system converts analog quantities into digital quantities via a data acquisition card, and utilizes a computer to monitor in real time or intermittently measure the following parameters: heating source power, solid-liquid interface shape and position, liquid electrolyte temperature, aluminum liquid temperature, solid-liquid interface temperature, anode upper surface temperature, side tank shell surface temperature, side air temperature, side ventilation flow rate, side heat flux density, and electrolyte height. A multi-channel heat flux meter is used to measure the heat flux density transmitted to the outer surface of the electrolyte melt. A thermocouple temperature module is used to collect various temperatures. A gas flow meter is used to collect the gas flow rate per unit time. The difference in electrolyte conductivity at different temperatures and in the solid-liquid phase is used to measure the electrolyte height and the changing behavior of the solid-liquid interface.

[0016] Furthermore, an iron probe was vertically immersed in the graphite crucible melt for 5-10 seconds before being removed and subjected to surface morphology analysis. The solidification interface traces formed on the probe surface allowed the position of the electrolyte-aluminum interface within the melt pool, as well as the furnace wall thickness, to be estimated.

[0017] Furthermore, during the experiment, strontium carbonate was added to the electrolyte as a tracer element, and samples were taken and analyzed to determine the content of the strontium tracer element, and the mass of the liquid electrolyte was calculated.

[0018] The present invention can realize multiple functions such as coordinated control of multiple temperature zones, gas-stirred electrolyte, and dynamic monitoring of furnace side. The experimental system has high data accuracy in multi-physical field coupling simulation, can clearly monitor the temperature changes at key positions of the electrolytic cell, and can accurately simulate non-steady-state processes under extreme load fluctuations, providing a reliable experimental basis for numerical model verification and optimization of industrial electrolytic cells, thermal balance optimization, flexible production regulation, and formulation of furnace side protection strategies. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 This is a schematic diagram of the external three-dimensional structure of a C-type electrolytic cell; among them, 1-steel shell, 2-anode lifting device, 3-heat exchanger.

[0020] Figure 2 Schematic diagram of a C-type electrolytic cell from a top view; wherein, 2-anode lifting device, 3-heat exchanger, 4-insulation layer, 5-heating layer, 6-heating unit silicon carbon rod, 7-thermocouple, 8-graphite crucible.

[0021] Figure 3 Schematic diagram of the three-dimensional structure of the insulation layer of a C-type electrolytic cell; 4 is the insulation layer, and 5 is the heating layer.

[0022] Figure 4 Schematic diagram of the three-dimensional structure of the heating layer of a C-type electrolytic cell; 6-heating unit silicon carbon rod, 7-thermocouple.

[0023] Figure 5 Schematic diagram of the electrolysis structure inside the crucible; 8-graphite crucible, 9-furnace side, 10-feeding port, 11-aluminum liquid, 12-electrolyte.

[0024] Figure 6 Schematic diagram of the vertical cross section of the anode; 13-anode carbon silicon rod, 14-through hole.

[0025] Figure 7 Schematic diagram of temperature zone distribution; 15-low temperature zone on the left, 16-high temperature zone on the left, 17-low temperature zone on the right, 18-high temperature zone on the right, 19-low temperature zone at the bottom, 20-high temperature zone at the bottom.

[0026] Figure 8 Schematic diagram of the three-dimensional structure of the crucible.

[0027] Figure 9 This is a temperature detection change diagram of some thermocouples. DETAILED DESCRIPTION

[0028] The technical solution of the present invention is clearly and completely described below in conjunction with the embodiments and drawings. It should be noted that the embodiments described in the present invention are only used to further explain and illustrate, and are not intended to limit the scope of its application. Based on the present invention, all other embodiments obtained by those skilled in the art without making any creative work are within the scope of protection of the present invention.

[0029] During electrolysis experiments, the shell material used on the anode shell surface was based on the composition of industrial electrolytic cells, with the following components by mass percentage: cryolite 30%-50%, cryolite 10%-20%, and alumina 30%-40%. The electrolyte was cryolite-based, supplemented with AlF3 (2.3%-2.93%), CaF2 (1%-5%), LiF (2.25%-3%), and Al2O3 (0.5%-3.1%), totaling 50 kg. The molten aluminum mass was 40 kg. The shell material thickness was adjustable from 50 mm to 300 mm, and the shell surface slope was adjustable from 15° to 75°.

[0030] In the embodiment, the outer dimensions of the graphite crucible are 200 cm long, 80 cm wide, and 140 cm high, with a sidewall thickness of 10 cm, a bottom thickness of 30 cm, and a slope angle of 45°. The anode is a rectangular parallelepiped, 80 cm long, 24 cm wide, and 66 cm high, and the anode temperature is basically maintained at 932°C. The carbon silicon rod is cylindrical, with a diameter of 6 cm and a length of 1.45 m.

[0031] The experimental system structure is as follows:

[0032] 1. The overall structure of the system is as follows Figure 1 and Figure 2 shown.

[0033] The C-type electrolytic cell consists of a steel shell 1, an insulation layer 4, a heating layer 5, a graphite crucible 8, a heat exchanger 3, and an anode assembly. The steel shell 1 is a steel protective structure that wraps the insulation layer 4 and the heating layer 5 and provides mechanical support. The insulation layer 4 is made of silicon nitride and silicon carbide refractory bricks and covers the outside of the heating layer 5 to reduce heat loss. Figure 3 The heating layer 5 is a hollow structure with multiple sets of independently controlled heating units built in. Each heating unit is equipped with several independently controlled heating unit silicon carbon rods 6, which are distributed on the side wall and bottom of the graphite crucible 8 to achieve regional temperature control. Figure 4 Heat exchanger 3 is installed on the side of the steel shell on the slope side of the crucible and connected to an air compressor. It adjusts the side wall temperature through forced air cooling, simulating the heat dissipation mechanism of an industrial tank.

[0034] 2. The anode is the main core functional component, and its structure is as follows Figure 6 shown.

[0035] The anode used in the present invention is a rectangular parallelepiped, and its size and shape can be adjusted according to actual needs. The position of the anode in the crucible is adjusted by the anode lifting device 2. A cavity and a longitudinal through-hole 14 are provided inside the anode. The cavity contains an anode carbon silicon rod 13 for anode heating. The upper end of the through-hole 14 is connected to an argon gas source. After the argon gas is heated by the anode through the through-hole, it is introduced into the electrolyte to achieve gas stirring of the electrolyte (when the electrolyte does not need to be stirred, the through-hole 14 is exposed to the atmosphere or connected to a gas recovery device to allow the anode gas to escape). The anode through-hole 14 is combined with the anode carbon silicon rod 13, and a gas stirring mechanism is utilized to achieve heated gas-driven melt flow.

[0036] The crucible is a trough with a slope on one side, and the three-dimensional structure is as follows Figure 8 As shown. The internal structure of the crucible during electrolysis is as follows Figure 5 As shown, the upper part of the graphite crucible 8 contains electrolyte 12, the lower part is aluminum liquid 11, and the side wall naturally forms a solid electrolyte layer, namely the furnace side 9. Multiple groups of thermocouples 7 are set inside and on the side wall of the graphite crucible 8 to monitor temperature changes in real time. The discharge port 10 is set above the anode shell surface, and materials are added to the melt manually.

[0037] 3. Temperature zone control such as Figure 7 As shown, the low-temperature zone and the high-temperature zone are controlled in coordination, and the heating and heat dissipation design is divided into different regions to reproduce the non-uniform temperature field of the industrial tank.

[0038] The high-temperature zone corresponds to the inter-electrode area between the anode and the aluminum liquid 11. The heating power is concentrated on the side wall and the bottom, simulating the resistance heat concentration effect of the industrial tank. When facing the heat exchanger, the left, right, and bottom areas of the crucible away from the heat exchanger correspond to the left high-temperature zone 16, the right high-temperature zone 18, and the bottom high-temperature zone 20, respectively.

[0039] The low-temperature zone corresponds to the side wall extension area of ​​the electrolytic cell. The heat exchanger 3 is used to force heat dissipation to maintain the side wall temperature, thereby promoting the stable formation of the furnace wall 9. When facing the heat exchanger, the left, right and bottom areas of the crucible close to the heat exchanger correspond to the left low-temperature zone 15, the right low-temperature zone 17 and the bottom low-temperature zone 19 respectively.

[0040] 4. Dynamic monitoring and regulation of the monitoring system.

[0041] Data acquisition: 50 thermocouples are distributed in each temperature zone, and temperature data is updated every second; a multi-channel heat flux meter measures heat flux density, and a gas flow meter (each argon cylinder has a meter to control the flow) records the argon flow.

[0042] Dynamic Control: Based on real-time temperature feedback, the power of the heating layer 5 and the anode carbon silicon rod 13 is adjusted to simulate the unsteady state process of an industrial tank. The power of the heating device can be adjusted within the range of 0-100kW.

[0043] Example 1

[0044] The experimental system was assembled and debugged according to the above requirements. The heating device operated at a power level set by the monitoring system's computer program: 21kW for the left high-temperature zone, 21kW for the right high-temperature zone, 7kW for the bottom high-temperature zone, 8kW for the left low-temperature zone, 8kW for the right low-temperature zone, and 4kW for the bottom low-temperature zone. As the experiment progressed, the power level was adjusted based on system feedback.

[0045] Argon gas is delivered to the anode from three cylinders, entering the electrolyte melt through the anode through-hole to stir the electrolyte. The flow rate can be adjusted using valves, specifically set as follows: Argon cylinder #1 has a flow rate of 2 L / h; Argon cylinder #2 has a flow rate of 3 L / h; and Argon cylinder #3 has a flow rate of 1 L / h. The total flow rate for all three cylinders is 6 L / h, and the ventilation time is set to 4.0 hours to ensure a stable gas environment within the electrolyzer that meets experimental requirements.

[0046] During the ventilation process, the thermocouples distributed in the C-type electrolytic cell transmit the measured temperature signal to the system in real time and dynamically display it at a frequency of one update per second. The entire experimental system is equipped with 50 temperature measuring thermocouples. Figure 9 The temperature variation with time of some thermocouples during the experiment is given, among which: T2 is located in the high-temperature zone at the bottom of the graphite crucible, 250 mm away from the bottom surface of the graphite crucible; T9 is located between the outer wall of the graphite crucible and the silicon carbide refractory brick; T12 is located between the solid electrolyte furnace side and the graphite crucible wall; T17 is set in the middle of the solid electrolyte furnace side, and its bottom is in contact with the high-molecular-weight electrolyte prefabricated block laid on the extension leg; T22 is set on the inner wall of the furnace side, closest to the anode, and the thermocouple test end is located on the surface of the high-molecular-weight prefabricated block on the upper part of the extension leg; T25 penetrates an anode air guide hole and protrudes about 50 mm from the bottom of the anode; T27 is a thermocouple buried in the electrolyte layer in the feeding port area; T28 is a thermocouple buried on the surface of the aluminum fluoride feeding port area.

[0047] It can be seen from this embodiment that the system can clearly monitor the temperature changes at key positions of the C-type electrolytic cell, and these data can be used to verify and optimize the numerical model.

[0048] Example 2

[0049] The argon flow rate was the same as in Example 1 (2 L / h for Argon Cylinder No. 1, 3 L / h for Argon Cylinder No. 2, and 1 L / h for Argon Cylinder No. 3, for a total flow rate of 6 L / h). The heating device operated continuously, with an initial load set to 40 kW (simulating full-load operation of an industrial tank) to maintain the electrolytic cell temperature environment. The process was divided into two stages: Stage 1, steady-state stage (0-6 hours), maintaining a steady-state load and recording the temperature field, heat flux density, and flow velocity distribution; Stage 2, load surge stage (6-12 hours), simulating a 20% current surge, with the heating power adjusted synchronously to monitor changes in the furnace wall thickness and thermal equilibrium response.

[0050] In the late stage of steady state, the furnace wall thickness stabilized at 12.5±0.3cm and the heat flux density was 4.2kW / m 2 (The heat flux meter is set in the middle of the two heat exchangers); after the heating power increased by 20% during the load surge phase, the furnace wall thickness was reduced to 8.2cm within 3 hours, and the heat flux density increased to 5.8kW / m 2 ; The numerical model based on Ansys (boundary conditions are consistent with the experiment) shows that the prediction error of the furnace wall thickness is ≤5% and the heat flux density error is ≤8%.

[0051] This example verifies the high data accuracy of the system in multi-physics field coupling simulation, which is significantly better than the assumption dependence of traditional simulation models and provides a reliable experimental benchmark for industrial tank thermal balance optimization.

[0052] Example 3

[0053] Argon gas is continuously introduced into the C-type electrolytic cell, with the following specific settings: the gas flow rate of argon bottle No. 1 is set to 5L / h; the gas flow rate of argon bottle No. 2 is set to 5L / h; the gas flow rate of argon bottle No. 3 is set to 1L / h; the total flow rate of the three argon bottles is 11L / h, and the ventilation time is set to 24.0 hours to ensure that the gas environment in the electrolytic cell is stable and meets the experimental requirements. The heating device works continuously, and the initial load is set to 40kW (simulating full-load operation of an industrial cell) to maintain the temperature environment of the electrolytic cell. The forced ventilation module starts when the load is reduced, and the air compressor flow rate is 240L / h. During the experiment, the load was reduced from 40kW to 10kW at the 12th hour, and the cover of the feeding port was opened. An iron rod was inserted into the molten electrolyte in the electrolytic cell and then quickly removed. By timely observing the condensation phenomenon on the iron rod, the thickness of the furnace wall can be reflected, and the heat flux density can be recorded at the same time. This operation was repeated at the 24th hour. The specific records are as follows:

[0054] Load sudden drop stage (40kW→10kW): furnace wall thickness increases from 10.5cm to 14.2cm, heat flux increases from 5.5kW / m 2 Reduced to 3.8kW / m 2 .

[0055] In this example, an iron rod is inserted into the melt to observe the surface solidification layer and capture the evolution of the furnace side thickness. The furnace side is dynamically monitored in combination with thermocouple data, proving that the experimental system can accurately simulate the non-steady-state process under extreme load fluctuations, providing an experimental basis for the flexible production control of industrial tanks and the formulation of furnace side protection strategies.

Claims

1. An experimental system for studying the thermal-electrical-fluid field coupling effect of a molten salt electrolyzer, characterized in that: The experimental system consists of two parts: a C-type electrolytic cell and a monitoring system; The C-type electrolytic cell mainly includes an outer shell, an insulation layer, a heating layer, a crucible, a heat exchanger, an anode, an anode lifting device, an electrolyte, molten aluminum, and a furnace side. The crucible is a trough with a slope on one side, and several thermocouples are installed inside the crucible. The heating layer is coated on the side walls and bottom of the crucible. The heating layer has a hollow structure and is equipped with several independently controlled heating units on the side walls and bottom. Each heating unit is equipped with several carbon silicon rods, which are connected to a power supply. The insulation layer is wrapped around the side walls and bottom of the heating layer, and the outer shell is wrapped around the side walls and bottom of the insulation layer. The heat exchanger is located on the outer shell of the crucible with a slope, and the heat exchanger is connected to an air compressor to cool the outer shell. The electrolyte and molten aluminum are located in the crucible, with the electrolyte at the top and the molten aluminum at the bottom. The furnace side is naturally formed on the side wall of the crucible during the electrolysis process. The anode is immersed in the electrolyte, and its position is changed by an anode lifting device. A cavity is provided inside the anode near the side wall and bottom, and a number of individually controlled carbon silicon rods are placed in the cavity, and the carbon silicon rods are connected to a power supply. The anode is provided with a number of longitudinal through holes. When the electrolyte needs to be stirred, the upper end of the through hole is connected to the gas source. When the electrolyte does not need to be stirred, the upper end of the through hole is exposed to the atmosphere or connected to a gas recovery device. The monitoring system includes a computer, a data acquisition card, a multi-channel heat flux meter module, a thermocouple temperature module, a gas flow meter module, and a heating module; among them, the multi-channel heat flux meter module records the heat flux density data around the heat exchanger, the thermocouple temperature module records the temperature data of thermocouples located at different positions of the crucible, the gas flow meter module records the gas flow data when the upper end of the anode through-hole is connected to the gas source, the heating module records and controls the parameters of the carbon silicon rod in the anode and the heating unit in the heating layer, and the data acquisition card converts the analog quantities recorded by each module into digital quantities, and uses a computer for real-time online monitoring or intermittent measurement.

2. The experimental system for studying the thermal-electrical-fluid field coupling effect of a molten salt electrolyzer according to claim 1, characterized in that: The shell is made of steel; the insulation layer is made of silicon nitride and silicon carbide refractory bricks; the crucible is made of graphite; and the anode is made of graphite.

3. An experimental method for studying the thermal-electrical-fluid field coupling effect of a molten salt electrolyzer, characterized in that: When the experimental system described in claim 1 or 2 is used to conduct a molten salt electrolytic cell experiment, it is divided into a high temperature zone and a low temperature zone, wherein: the high temperature zone corresponds to the inter-electrode area between the anode and the aluminum liquid in the electrolytic cell, which is equivalent to the high current density area between the traditional anode and cathode, and the heating layer is used to simulate the resistance heat concentration effect in the industrial cell, and the temperature range is 940°C-980°C; the low temperature zone corresponds to the area where the crucible with the sloped side furnace wall extends in the electrolytic cell, and the heat exchanger is used to simulate the side wall forced heat dissipation mechanism to promote the generation and maintenance of the solid electrolyte layer, and the temperature range is 880°C-920°C; through regional temperature control and dynamic power adjustment, the non-uniform temperature field distribution and the dynamic evolution process of the furnace wall of the industrial electrolytic cell are reproduced.

4. The experimental method for studying the thermal-electrical-fluid field coupling effect of a molten salt electrolyzer according to claim 3, characterized in that: For different stages of the electrolysis process, the monitoring system records the temperature information transmitted by thermocouples at different positions in the crucible in real time and dynamically monitors the temperature. At the same time, the monitoring system adjusts the power of the heating unit in the heating layer and the power of the carbon silicon rod in the anode according to the real-time temperature information, controls the heating of the crucible and the anode, and achieves the purpose of controlling electrolysis. It simulates the non-uniform temperature distribution caused by the current change of the industrial cell, as well as the steady-state and non-steady-state processes of the industrial cell at different electrolysis stages.

5. The experimental method for studying the thermal-electrical-fluid field coupling effect of a molten salt electrolyzer according to claim 3, characterized in that: When the electrolyte needs to be stirred, the upper end of the anode through-hole is connected to a gas source, which is an inert gas or air. The gas flow is regulated by a monitoring system. The gas absorbs heat when passing through the anode with a carbon silicon rod inside. After the temperature rises, it enters the electrolyte melt to drive the electrolyte flow, achieving the effect of gas stirring the electrolyte. When the electrolyte does not need to be stirred, the anode through-hole is used for the anode gas to escape.

6. The experimental method for studying the thermal-electrical-fluid field coupling effect of a molten salt electrolyzer according to claim 3, characterized in that: An iron probe is vertically immersed in the electrolytic cell melt and kept immersed for 5s-10s before being taken out. The position of the electrolyte and aluminum liquid interface in the molten pool and the thickness of the furnace wall are inferred based on the solidification phase interface traces formed on the probe surface.

7. The experimental method for studying the thermal-electrical-fluid field coupling effect of a molten salt electrolyzer according to claim 3, characterized in that: Strontium carbonate is added to the electrolyte as a tracer element, and the content of the tracer element is analyzed by sampling to infer the mass of the liquid electrolyte.

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