A molten salt flow corrosion and thermal stability testing device

Abstract

The present invention discloses a device and method for testing the flow corrosiveness and thermal stability of molten salt, which belongs to the field of thermal property testing of energy storage high-temperature molten salt. The device includes: an experimental test subsystem, a heating constant temperature subsystem, and an information acquisition and control subsystem; the experimental test subsystem includes a W-shaped quartz tube, an air pump, and a molten salt tank; the W-shaped quartz tube includes a vertical first quartz tube, a second quartz tube, and a third quartz tube, and the lower ends of the three vertical quartz tubes are connected to accommodate the high-temperature molten salt to be tested. The present invention detects the dynamic and static thermal stability of the molten salt by detecting the penetration rate of infrared rays through the capillary tube, and can also detect the corrosiveness of the molten salt in two states of long-term immersion and scouring. The detection of molten salt by the present invention is more in line with the working state of the molten salt, with high accuracy, and is intelligent and convenient.

Description

Technical Field

[0001] The present invention belongs to the field of thermal property testing of energy storage high-temperature molten salt, and in particular relates to a molten salt flow corrosion and thermal stability testing device. Background Art

[0002] As an inorganic compound, molten salt has low electrical conductivity, low viscosity, good thermal conductivity, weak corrosiveness, low vapor pressure, a wide operating temperature range, and low price, making it the preferred heat transfer and heat storage medium. The molten salt materials are mainly binary nitrate molten salt (60% NaNO3-40% KNO3) and ternary nitrate molten salt (40% NaNO2-53% KNO3-7% NaNO3). The melting point of the binary nitrate molten salt system is relatively high, and in practical applications, more energy is consumed to maintain it. Although the melting point of the ternary nitrate system is relatively low, its upper operating temperature is also low. In practice, due to different experimental research conditions, the conclusions on thermal stability performance vary greatly. Currently, there is a lack of a molten salt stability test device that can detect the thermal stability and corrosiveness of molten salt in a flowing state, conform to the actual operation conditions of molten salt on site, and have high accuracy.

[0003] Research on the thermal stability and corrosion properties of PCMs after long-term melting / solidification cycles has primarily focused on PCMs such as acids, alcohols, waxes, greases, and molten salt-based composites. However, comprehensive research on the corrosion properties of pure molten salts is relatively lacking. In summary, the thermal stability and corrosion properties after long-term melting / solidification cycles provide valuable insights for the design, construction, and engineering applications of mobile molten salt thermal storage systems.

[0004] An invention patent application (CN112255260A) discloses a test device for testing the thermal stability of materials under constant pressure. This device is simple and safe to operate, has excellent pressure resistance and corrosion resistance, and produces highly accurate results. The thermal stability data obtained from the test provides a good representation of the safety and reaction characteristics of the sample when subjected to thermal stimulation. However, this solution cannot test the thermal stability of samples in a flowing state.

[0005] A utility model patent (CN214794547U) discloses a device for testing the thermal stability of chemicals. The device features a movable plate that allows for more uniform heating of the chemicals within a beaker, allowing for simultaneous heating of multiple test samples. However, this test fails to assess the corrosiveness of the test samples, and the temperature range required for testing does not meet the requirements for molten salts.

[0006] The main testing methods for the stability and corrosiveness of molten salts include: muffle furnace, DSC, TG, laboratory-made devices, etc. In summary, the above methods have some defects, mainly: (1) they cannot test the thermal stability and corrosiveness of molten salts in a flowing state; (2) they cannot test the erosion corrosion of molten salts on metals; (3) testing methods such as DSC and TG can often only test trace amounts of samples, especially when testing highly dangerous substances such as energetic materials, the test amount is often at the milligram level.

[0007] The corrosion and thermal decomposition of molten salt occur simultaneously, and current tests cannot test stability and corrosion at the same time. Summary of the Invention

[0008] In order to solve the problems of flow corrosion and thermal stability testing in the prior art, the present invention proposes a molten salt flow corrosion and thermal stability testing device, which includes: an experimental testing subsystem, a heating and constant temperature subsystem, and an information collection and control subsystem.

[0009] The experimental test subsystem is located inside the heating and constant temperature subsystem and includes a W-shaped quartz tube, an air pump, and a molten salt tank. The W-shaped quartz tube includes a first quartz tube, a second quartz tube, and a third quartz tube arranged vertically. The three vertical quartz tubes are parallel to each other and connected at their lower ends. The upper end of the first quartz tube is sealed and the middle section is a quartz capillary section. The upper end of the second quartz tube is connected to the air pump, and the upper end of the third quartz tube is connected to the molten salt tank. The orifice of the first quartz tube is provided with an air hole, which can be opened or closed.

[0010] The heating and constant temperature subsystem provides a temperature environment and a gas atmosphere for the experimental test subsystem inside it;

[0011] The information acquisition and control subsystem includes a computer, an infrared emitting board, and an infrared receiving board; the infrared emitting board emits infrared rays, and the infrared receiving board receives and detects infrared rays that pass through the quartz capillary segment. The information acquisition and control subsystem collects working status data inside the device, adjusts the internal environment of the heating constant temperature subsystem based on the collected data, and controls the periodic opening and closing of the air pump.

[0012] The present invention also proposes a testing method based on the molten salt flow corrosion and thermal stability testing device, which is characterized by comprising the following steps:

[0013] 1) Preheating of the heating and constant temperature subsystem;

[0014] 2) Add the high-temperature molten salt to be tested from the molten salt addition port on the molten salt tank cover. Keep the air holes of the first quartz tube and the three-way air valve of the second quartz tube open so that the molten salt liquid levels in the three quartz tubes of the W-shaped quartz tube are all at line A.

[0015] The line A is a horizontal line, which is higher than the second metal to be measured and the upper end of the capillary quartz tube segment and lower than the lower end of the first metal to be measured.

[0016] 3) The computer receives signals from the power signal box to control the periodic opening and closing of the air pump to achieve molten salt thermal circulation;

[0017] 4) maintaining a molten salt thermal cycle for 200-2000 hours; while maintaining the molten salt thermal cycle, turning on the infrared emitting board at different times to irradiate the high-temperature molten salt to be tested in the capillary quartz tube segment, and the infrared receiving board receives the infrared rays that penetrate the capillary quartz tube segment and transmits the infrared intensity signal to the computer to obtain the thermal stability of the high-temperature molten salt to be tested;

[0018] 5) While maintaining the molten salt thermal cycle, the first metal to be tested and the second metal to be tested in the molten salt tank are collected and updated at different times to obtain the flow corrosion of the high-temperature molten salt to be tested.

[0019] Preferably, the step 3) is specifically as follows:

[0020] a) In the initial state, the liquid level of the high-temperature molten salt to be measured is at line A;

[0021] b) The air pump applies pressure to the second quartz tube, so that the high-temperature molten salt to be tested in the third quartz tube is pressed and raised into the molten salt tank;

[0022] c) when both the second current connector and the first current connector are immersed in the high-temperature molten salt to be tested, the computer receives a signal from the power signal box and turns off the air pump, causing the liquid level of the high-temperature molten salt to be tested in the third quartz tube to drop;

[0023] d) The liquid level of the high-temperature molten salt to be tested returns to the position of line A. At this time, the second current connector and the first current connector are both above the molten salt liquid level. The air pump is turned on to re-press the high-temperature molten salt to be tested in the third quartz tube into the molten salt tank;

[0024] e) Repeat steps c) and d) to maintain the flow state of the high-temperature molten salt to be tested.

[0025] Compared with the prior art, the present invention has the following innovations and beneficial effects:

[0026] (1) The thermal stability and corrosiveness of the flowing molten salt are tested simultaneously, which is more consistent with the working state of the molten salt;

[0027] (2) Carry out molten salt corrosion tests on metals that are immersed for a long time and metals that are immersed intermittently, respectively, to test the erosion corrosion of the molten salt on the metal, which is more consistent with the working state of the molten salt;

[0028] (3) The thermal stability and stratification of the molten salt in static and dynamic scenarios are analyzed by using the different infrared penetration properties of the molten salt. The prior art does not have a means of detecting the stability of the molten salt by optical methods. The infrared detection method used in the present invention not only makes the detection process clearer and more visual, but also ensures direct detection without changing the operating environment of the molten salt, which is closer to the scene. In addition, the decomposition and stratification phenomenon is not easily detected by existing conventional detection methods, but the infrared testing method of the present invention can detect it.

[0029] (4) The sample can be treated with nitrogen to prevent the influence of gas impurities on the corrosiveness of the molten salt;

[0030] (5) The combination of electrical signals and thermal signals is used to collect and process data through computers, which is more intelligent and accurate. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1 Schematic diagram of the molten salt flow corrosion and thermal stability testing device of the present invention;

[0032] Figure 2 Schematic diagram of the experimental test subsystem in the embodiment;

[0033] Figure 3 Schematic diagram of the molten salt tank part in the embodiment;

[0034] Figure 4 Schematic diagram of the power signal box in the embodiment;

[0035] Figure 5 Schematic diagram of the heating constant temperature subsystem in the embodiment;

[0036] Figure 6 2 is a top cross-sectional view of the molten salt flow corrosion and thermal stability testing device in the embodiment. DETAILED DESCRIPTION

[0037] The present invention will be further described and illustrated below in conjunction with specific embodiments. The embodiments are merely illustrative of the present disclosure and do not limit its scope. The technical features of the various embodiments of the present invention may be combined accordingly, provided that there is no conflict between them.

[0038] like Figure 1 As shown, the high-temperature molten salt flow corrosion and stability testing device of this embodiment mainly includes three parts: an experimental testing subsystem 101, a heating and constant temperature subsystem 102, and an information acquisition and control subsystem 103. The experimental testing subsystem 101 is placed inside the heating and constant temperature subsystem 102, and the information acquisition and control subsystem 103 is connected to the experimental testing subsystem 101 and the heating and constant temperature subsystem 102 via wires.

[0039] like Figure 2 As shown, the experimental test subsystem includes: a W-shaped quartz tube 101-1, a high-temperature molten salt to be tested 101-2, an air pump 101-3, a three-way air valve 101-4, a high-temperature resistant plug 101-5, an air pipe 101-6, a molten salt tank cover 101-7, a metal sheet clamp 101-8, a first metal to be tested 101-9, a second metal to be tested 101-10, a first current connector 101-11, a second current connector 101-12, a molten salt tank 101-13, an air hole 101-14, a quartz capillary segment 101-15, an infrared emitting board 103-3, an infrared receiving board 103-4, a power signal box 101-16, and a molten salt addition port 101-17.

[0040] The main body of the experimental test subsystem is a W-shaped quartz tube 101-1; the W-shaped quartz tube includes a first vertical quartz tube, a second quartz tube, and a third quartz tube, and the lower ends of the three vertical quartz tubes are connected; the first quartz tube is sealed and the middle section is a quartz capillary section, the second quartz tube is connected to the air pump, and the third quartz tube is connected to the molten salt tank; the diameter of the quartz capillary section 101-15 is much smaller than that of the other parts, and the diameter of the quartz capillary section 101-15 is preferably 10-15 mm, and the first quartz tube is 10-15 mm. The diameter of the remaining portion of the tube is preferably 30-50 mm; the high-temperature molten salt 101-2 to be tested is filled into the W-shaped quartz tube 101-1; the leftmost port of the quartz tube is connected to the molten salt tank 101-13; the molten salt tank 101-13 is used to hold the molten salt; the molten salt tank cover 101-7 seals the molten salt tank 101-13, and the molten salt tank cover 101-7 is provided with a first current connector 101-11, a second current connector 101-12, a metal sheet clamp 101-8, and a molten salt addition port 101-17.

[0041] like Figure 3 As shown, a first metal to be tested 101-9 and a second metal to be tested 101-10 are fixed to the molten salt tank cover 101-7 by a metal sheet clamp 101-8. The first metal to be tested is fixed at a higher position and is located entirely in the molten salt tank, while the second metal to be tested is fixed at a position entirely in the third quartz tube. Preferably, the first metal to be tested and the second metal to be tested are both rectangular metal sheets.

[0042] like Figure 4As shown, the power signal box 101-16 connects the first current connector 101-11 and the second current connector 101-12. If the molten salt submerges the first current connector 101-11 and the second current connector 101-12, the power signal box 101-16 will collect the current signal. The first current connector 101-11 includes two open wire ends with a gap between them. If the molten salt submerges the two wire ends, the first current connector will form a path, thereby outputting the current signal. The function of the second current connector is the same as that of the first current connector. The first current connector is higher than the upper end of the first metal to be tested, and the second current connector is lower than the lower end of the first metal to be tested and higher than the upper end of the second metal to be tested.

[0043] The current signal box 101-16 is used to detect the current signal output when the first and second current connectors form a path, and transmit the signal to the information acquisition and control subsystem 103. It mainly includes a first current signal meter 101-16-1, a second current signal meter 101-16-2, a signal collector 101-16-3, and a power supply 101-16-4. The first current signal meter 101-16-1 and the second current signal meter 101-16-2 are respectively used to detect whether a current signal is passing through the first and second current connectors.

[0044] The ports of the W-shaped quartz tube 101-1, the second quartz tube, and the first quartz tube are all sealed by a high-temperature resistant plug 101-5, which has an air hole 101-14. The air hole 101-14 on the second quartz tube is connected to a three-way air valve 101-4, and the air hole on the first quartz tube can be opened or closed. One end of the three-way air valve 101-4 is connected to the air pipe 101-6, and the other end is connected to the air pump 101-3. The air pump 101-3 is a key power component for maintaining the fluidity of the molten salt.

[0045] Figure 2 The approximate positions of Lines A and B are marked. Lines A and B are horizontal lines. Line A is above the second metal to be tested and the upper end of the capillary quartz tube segment, and below the lower end of the first metal to be tested. Line B needs to be located below the diameter reduction point at the bottom of the quartz capillary tube segment. In the initial state, the molten salt is filled to the position of Line A. Air pump 101-3 is turned on to press the molten salt in the second quartz tube to the position of Line B, causing the high-temperature molten salt to be tested in the third quartz tube to be pressed and raised into the molten salt tank. At this time, current is flowing through both the first current connector 101-11 and the second current connector 101-12. Air pump 101-3 is turned off, and the molten salt flows back to fill the position of Line A. At this time, no current is flowing through the first current connector 101-11 and the second current connector 101-12. Air pump 101-3 is turned on again to press the molten salt in the second quartz tube to the position of Line B.

[0046] like Figure 5As shown, the heating and constant temperature subsystem 102 mainly includes: a high-temperature heating furnace 102-1, a heating element 102-2, a heat-insulating material 102-3, a sealing plug 102-4, a sealing plate 102-5, a stainless steel box 102-6, a support frame 102-7, a thermocouple 102-8, a signal transmission port 102-9, and a nitrogen inlet port 102-10. The information acquisition and control system 103 includes: a computer 103-1 and a nitrogen pump 102-11.

[0047] The stainless steel box 102-6 is vertically nested in the high-temperature heating furnace 102-1 to provide an experimental test environment; the heating element 102-2 is wrapped around the outer periphery of the stainless steel box 102-6 to heat and keep the stainless steel box 102-6 warm. According to the needs of the test, the heating power is changed to provide different test temperatures; the interior of the high-temperature heating furnace 102-1 is provided with an insulation material 102-3 to slow down heat loss; the sealing plate 102-5 covers the upper part of the stainless steel box 102-6 to seal the stainless steel box 102-6; the thermocouple 10 2-8 passes through the sealing plate and protrudes from the top of the stainless steel box 102-6 to detect the temperature change inside the box; the signal transmission hole 102-9 is a hole in the sealing plate through which the signal transmission line of the experimental test subsystem device passes; the nitrogen pump 102-11 passes through the sealing plate 102-5 through the nitrogen input hole 102-10 to provide a nitrogen environment for the stainless steel box 102-6; the sealing plug 102-4 is used to connect the sealing plate 102-5 and the stainless steel box 102-6; the nitrogen pump 102-12 passes nitrogen into the stainless steel box 102-6 through the nitrogen pipe 102-13.

[0048] The information collection and control subsystem 103 mainly includes a computer 103-1, a signal collection line 103-2, an infrared emitting board 103-3, and an infrared receiving board 103-4.

[0049] Computer 103-1 is located outside the high-temperature heating furnace and is used to collect temperature and current data from thermocouple 102-8, infrared emitting board 103-3, infrared receiving board 103-4, and heating element 102-2, as well as from signal box 101-16. Based on this data, it controls the heating element and nitrogen pump to regulate the temperature and gas inside the heating constant temperature subsystem 102, and controls the periodic opening and closing of the gas pump to maintain the circulation of the molten salt in the W-shaped quartz tube. Signal collection line 103-2 is connected to thermocouple 102-8, power signal box 101-16, infrared emitting board 103-3, and infrared receiving board 103-4. Infrared emitting board 103-3 and infrared receiving board 103-4 are located on either side of quartz capillary segment 101-15. Infrared emitting board 103-3 is used to transmit infrared rays, while infrared receiving board 103-4 is used to receive and detect infrared rays from the molten salt that pass through the quartz capillary segment.

[0050] like Figure 6 This is a top cross-sectional view of the device of this embodiment. The infrared emitting board 103-3 and the infrared receiving board 103-4 are located on both sides of the quartz capillary section 101-15 and fixed on the stainless steel box 101-6. The support frame 102-7 is used to fix the W-shaped quartz tube 101-1.

[0051] In this embodiment, the principle of maintaining the fluidity of the molten salt is as follows: in the initial state, the molten salt is filled in the W-shaped quartz tube, and the height is at the position of line A. The air pump starts to pressurize, forcing the molten salt in the second quartz tube to the position of line B. At this time, because the first quartz tube is closed and the molten salt tank port is open, the molten salt will be forced into the molten salt tank, and the molten salt will gradually immerse the second current connector and the first current connector. When both current connectors are immersed, the air pump is powered off, and the molten salt begins to return to the second quartz tube due to gravity, gradually restoring the liquid level at position A. Then, the second current connector and the first current connector are both above the molten salt liquid level. At this time, the air pump is turned on to re-force the molten salt into the molten salt tank. In this way, the fluid state of the molten salt in the quartz tube can be maintained.

[0052] In this embodiment, the static thermal stability test of the molten salt is to detect the thermal stability of the molten salt by measuring the different infrared penetration of the molten salt fluid in different stratification situations. The provision of the capillary quartz tube segment makes the test clearer and more accurate. The test principle is that during the static test, since the air holes on the first quartz tube remain closed during the test, and the molten salt addition port on the molten salt tank cover remains open, when the air pump is turned on, the molten salt tank port is always at atmospheric pressure. Therefore, the molten salt in the second quartz tube will be forced into the molten salt tank and will not form convection on the molten salt in the capillary quartz tube segment. When the air pump is turned off, due to the presence of the three-way air valve, the air pressure in the second quartz tube is also at atmospheric pressure. The molten salt will flow from the molten salt tank into the second quartz tube and will not interfere with the molten salt in the capillary quartz tube segment. Therefore, the fluidity test of the molten salt will not interfere with the static thermal stability test of the capillary quartz tube segment. Even if there is no significant flow in the capillary section, it will still flow and mix with the molten salt in the second and third quartz tubes to a certain extent, so it can also be considered as quasi-dynamic thermal stability.

[0053] During the molten salt dynamic thermal stability test, the air holes of the first quartz tube remain open during the test. In this way, the opening and closing of the air pump will drive the molten salt in the capillary quartz tube section to convect and participate in the thermal cycle, thereby achieving dynamic thermal stability testing.

[0054] The principle of the molten salt flow corrosion test in this embodiment is to test the corrosion of metals under both long-term and intermittent immersion in molten salt. During the molten salt circulation caused by the aforementioned air pump, the second metal under test is always immersed in the molten salt, and the molten salt is always flowing, while the first metal under test is intermittently immersed. These two different states can simultaneously demonstrate the flow corrosion of the molten salt on the metal.

[0055] The high-temperature molten salt flow corrosivity and thermal stability test device designed in this embodiment can be used to measure the corrosivity and thermal stability of high-temperature molten salt fluids and other conductive, corrosive, and other liquids in a flowing state. The specific measurement steps are as follows:

[0056] (1) Turn on the computer, prepare the power supply, and preheat the heating and constant temperature subsystem 102;

[0057] (2) Add the high-temperature molten salt fluid solution to be tested from the molten salt addition port of the molten salt tank cover. Keep the air holes of the first quartz tube and the three-way air valve of the second quartz tube open so that the molten salt liquid levels in the three quartz tubes of the W-shaped quartz tube are all located at the A line position. The addition of the molten salt to be tested is completed.

[0058] (3) Close the pores of the first quartz tube, open the molten salt addition port, seal the stainless steel box, and fill the test environment with nitrogen or gas as needed, and circulate the gas for 5 minutes;

[0059] (4) After the test starts, the data acquisition operation panel on the computer controls the periodic opening and closing of the air pump by receiving the signal from the power signal box to realize the molten salt thermal cycle;

[0060] (5) Testing the molten salt thermal cycle for 1000 hours. At 250 hours, 500 hours, 750 hours, and 1000 hours, the infrared emitting board was turned on to irradiate the molten salt in the capillary quartz tube, thereby collecting data from the infrared receiving board and transmitting it to the data acquisition operation panel on the computer to obtain the thermal stability of the molten salt.

[0061] (6) After different cycle times, the first metal to be tested and the second metal to be tested in the molten salt tank are collected and updated to obtain the molten salt flow corrosion.

[0062] The above-described embodiments merely illustrate several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. Persons skilled in the art will readily appreciate that variations and modifications may be made without departing from the scope of the present invention, all of which fall within the scope of protection of the present invention.

Claims

1. A molten salt flow corrosion and thermal stability testing device, characterized in that: It includes: Experiment Testing subsystem (101), heating and constant temperature subsystem (102), information collection and control subsystem (103); The experimental test subsystem (101) is located inside the heating constant temperature subsystem (102), and includes a W-shaped quartz tube, an air pump, a molten salt tank, a molten salt tank cover, and a power signal box; the W-shaped quartz tube includes a first quartz tube, a second quartz tube, and a third quartz tube arranged vertically, and the three vertically arranged quartz tubes are parallel to each other and connected at the lower ends; the upper end of the first quartz tube is sealed and the middle section thereof is a quartz capillary section, the upper end of the second quartz tube is connected to the air pump, and the upper end of the third quartz tube is connected to the molten salt tank; an air hole is provided at the tube mouth of the first quartz tube, and the air hole can be opened or closed; The molten salt tank is sealed by a molten salt tank cover, which is provided with a first current connector, a second current connector, two metal sheet clamps, and a molten salt addition port; the first current connector and the second current connector have a height difference, which is used to detect the liquid level in the molten salt tank; the two metal sheet clamps are used to respectively fix the first metal to be tested and the second metal to be tested; The lower end of the first metal to be tested is higher than the upper end of the second metal to be tested, the first metal to be tested is located in the molten salt tank, and the second metal to be tested is located in the third quartz tube; The first current connector is higher than the upper end of the first metal to be tested, and the second current connector is lower than the lower end of the first metal to be tested and higher than the upper end of the second metal to be tested; The power signal box is connected to the first current connector and the second current connector, and is used to detect the output current signal when any current connector forms a path, and transmit the signal to the information acquisition and control subsystem (103); The information acquisition and control subsystem (103) includes a computer, an infrared emitting board, and an infrared receiving board; the infrared emitting board emits infrared rays, and the infrared receiving board receives and detects infrared rays that pass through the quartz capillary segment. The information acquisition and control subsystem acquires working status data inside the device, adjusts the internal environment of the heating constant temperature subsystem (102) based on the acquired data, and controls the periodic opening and closing of the air pump by receiving a signal from a power signal box.

2. The testing device according to claim 1, wherein: The air pump in the experimental test subsystem (101) is connected to the second quartz tube via a three-way air valve, so that the second quartz tube is in a normal pressure state when the air pump is not started.

3. The testing device according to claim 1, wherein: The diameter of the quartz capillary section in the experimental test subsystem (101) is smaller than the diameter of the non-capillary section of the first quartz tube. The diameter of the quartz capillary section is 10 mm to 15 mm, and the diameter of the non-capillary section is 30 mm to 50 mm.

4. The testing device according to claim 1, wherein: The heating constant temperature subsystem (102) comprises a high-temperature heating furnace, a stainless steel box sealed and nested in the high-temperature heating furnace, a thermocouple for detecting the temperature inside the stainless steel box, a sealing plate for sealing the stainless steel box, a heating element arranged on the periphery of the stainless steel box, a heat-insulating material arranged between the stainless steel box and the high-temperature heating furnace, and a support frame inside the stainless steel box for fixing the experimental test subsystem, wherein the thermocouple is arranged on the sealing plate.

5. The testing device according to claim 4, characterized in that: The heating constant temperature subsystem (102) further includes a nitrogen pump, which is connected to the stainless steel box and is used to provide a nitrogen environment for the experimental test subsystem (101).

6. A method for testing the flow corrosion and thermal stability of molten salt using the testing device according to claim 1, characterized in that: The following steps are involved: 1) Preheating the heating and constant temperature subsystem (102); 2) Add the high-temperature molten salt to be tested from the molten salt addition port on the molten salt tank cover. Keep the air holes of the first quartz tube and the three-way air valve of the second quartz tube open so that the molten salt liquid levels in the three quartz tubes of the W-shaped quartz tube are all at line A. The line A is a horizontal line, which is higher than the second metal to be tested and the upper end of the capillary quartz tube segment and lower than the lower end of the first metal to be tested; 3) The computer receives signals from the power signal box to control the periodic opening and closing of the air pump to achieve molten salt thermal circulation; 4) Maintaining a molten salt thermal cycle for 200-2000 hours; while maintaining the molten salt thermal cycle, turning on the infrared emitting board at different times to irradiate the high-temperature molten salt to be tested in the capillary quartz tube segment, and the infrared receiving board receives the infrared rays that penetrate the capillary quartz tube segment and transmits the infrared intensity signal to the computer to obtain the thermal stability of the high-temperature molten salt to be tested; 5) While maintaining the molten salt thermal cycle, the first metal to be tested and the second metal to be tested in the molten salt tank are collected and updated at different times to obtain the flow corrosion of the high-temperature molten salt to be tested.

7. The method according to claim 6, characterized in that After sealing the pores of the first quartz tube in step 2), the nitrogen pump needs to be turned on to allow nitrogen to fill the interior of the heating constant temperature subsystem (102); In the step 2), when the static thermal stability of the molten salt is tested, the pores of the first quartz tube are closed; when the dynamic thermal stability of the molten salt is tested, the pores of the first quartz tube are opened.

8. The method according to claim 6, characterized in that The step 3) is specifically as follows: a) In the initial state, the liquid level of the high-temperature molten salt to be measured is at line A; b) The air pump applies pressure to the second quartz tube, so that the high-temperature molten salt to be tested in the third quartz tube is pressed and raised into the molten salt tank; c) when both the second current connector and the first current connector are immersed in the high-temperature molten salt to be tested, the computer receives a signal from the power signal box and turns off the air pump, causing the liquid level of the high-temperature molten salt to be tested in the third quartz tube to drop; d) The liquid level of the high-temperature molten salt to be tested returns to the position of line A. At this time, the second current connector and the first current connector are both above the molten salt liquid level. The air pump is turned on to re-press the high-temperature molten salt to be tested in the third quartz tube into the molten salt tank; e) Repeat steps c) and d) to maintain the flow state of the high-temperature molten salt to be tested.

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