CN105334138B - The fused salt infiltration experimental provision of MSR carbon materials - Google Patents

Abstract

The invention discloses a molten salt impregnation experimental device for carbon materials used in molten salt reactors. The device includes: autoclave, glove box, well-type atmosphere furnace, gas system, hoisting device, sample lifting device; the well-type atmosphere furnace is located under the glove box, and its furnace mouth is embedded in the glove box and sealed with the glove box bottom plate through the flange connection; the autoclave and the sample lifting device are located inside the glove box; the autoclave includes a detachable kettle body and a kettle cover; the sample lifting device uses a screw lifting mechanism to separate the molten salt from the experimental sample at high temperature; the upper part of the glove box is set There is a visual box sealed and connected to the glove box, and the lifting device is installed in the visible box; the gas circuit system is arranged outside the glove box, and communicates with the inside of the autoclave through a high-temperature-resistant pipeline, which is used to adjust the pressure of the autoclave. internal air pressure. Compared with the prior art, the invention can more safely and conveniently complete the separation of the molten salt and the sample at high temperature, and can accurately adjust the experimental air pressure to obtain more accurate experimental results.

Description

Experimental device for molten salt impregnation of carbon materials for molten salt reactors

technical field

The invention relates to a high-temperature molten salt experimental device, in particular to a molten salt impregnation experimental device for carbon materials used in a molten salt reactor (MSR).

Background technique

Molten salt reactor is a kind of nuclear fission reactor. Its main coolant is a kind of molten mixed salt, which can maintain low vapor pressure when working at high temperature (for higher thermal efficiency), thereby reducing mechanical stress and improving Safe and less active than molten sodium coolant. Due to the advantages of safety, high efficiency, easy miniaturization, and less impact on the environment, molten salt reactors have been studied by countries around the world as future advanced nuclear energy technologies.

Since the structural materials used in molten salt reactors (mainly including two types of alloys and carbon materials) need to be in contact with molten salt under high temperature and high pressure, due to the influence of molten salt, the mechanical and thermal properties of materials will change to varying degrees , which in turn may have an impact on the service life of the material and the safety of the reactor. Therefore, in order to ensure the safety of the molten salt reactor, it is necessary to conduct experimental research on the molten salt resistance characteristics of the structural materials used in the molten salt reactor.

For metal alloy materials, it is usually concerned about its corrosion behavior in a high temperature molten salt environment, and the high temperature molten salt corrosion test is the main technical means to understand the alloy's resistance to high temperature molten salt corrosion. However, at present, various research units use self-designed experimental devices when conducting high-temperature molten salt corrosion experiments, and there is no unified industry standard and technical specification. Figure 1 shows the basic structure of a molten salt corrosion experimental device commonly used at home and abroad. The molten salt corrosion experiment is carried out in a graphite crucible, and the sample is fixedly installed on a graphite rod in the graphite crucible. In order to ensure that the experiment is carried out in a closed environment, the graphite crucible is placed in a metal tank made of 304 stainless steel. Before the experiment started, the metal tank was sealed and welded. After the experiment was over, when the temperature of the molten salt dropped to about 500°C, the entire molten salt corrosion test device was turned upside down, so that the molten salt could be separated from the sample before the molten salt solidified. When the temperature drops to room temperature, the metal can is cut open. The entire above experiment process was carried out in a glove box with argon protective gas to prevent the corrosion data from being inaccurate due to the molten salt absorbing water.

For the carbon materials used in molten salt reactors (such as nuclear graphite, carbon-carbon composite materials, etc.), it is usually concerned about the infiltration of carbon materials by high-temperature molten salt, so it is necessary to simulate the actual operation of molten salt reactors Environment Carry out high-temperature molten salt impregnation experiment on carbon materials, that is, in a specific experimental temperature, pressure and molten salt medium, the sample with porous material is immersed in molten salt for a certain period of time, and then taken out to test the amount of molten salt infiltration . At present, no dedicated molten salt infiltration experimental device has been disclosed. When conducting molten salt infiltration experiments, researchers usually directly use existing molten salt corrosion experimental devices, such as the device shown in FIG. 1 . However, when using the existing molten salt corrosion experimental equipment to carry out the molten salt impregnation experiment of carbon materials, there are generally the following disadvantages: (1) the test samples are limited; Separation is dangerous, and each experiment needs to consume a metal tank, and the cost of the experiment is too high; (3) Different from the molten salt corrosion characteristics of alloys, carbon materials will show different infiltration characteristics under different pressures, and the current There is a molten salt corrosion experimental device without an air pressure control system, so it is impossible to test the influence of changes in air pressure on the results of the infiltration experiment.

In summary, there is an urgent need for a safe and effective molten salt infiltration experimental device, which can accurately test the molten salt infiltration characteristics of carbon materials for molten salt reactors.

Contents of the invention

The technical problem to be solved by the present invention is to overcome the deficiencies in the prior art and provide a molten salt impregnation experimental device for carbon materials used in molten salt reactors, which can more safely and conveniently complete the separation of molten salt and samples at high temperatures, and can Accurately adjust the experimental air pressure to obtain more accurate experimental results.

The molten salt impregnation experimental device for carbon materials used in molten salt reactors of the present invention includes: an autoclave, a glove box, a well-type atmosphere furnace, a gas system, a hoisting device, and a sample lifting device; the well-type atmosphere furnace is located under the glove box , the furnace mouth is embedded in the glove box and sealed with the bottom plate of the glove box through the flange; the autoclave and the sample lifting device are located inside the glove box; the autoclave includes a separable kettle body and a kettle cover; Screw rod, support frame, rotating nut, lifting ring, sample cabin, wherein, the bottom of the support frame is fixedly connected with the lid of the autoclave, and the top of the support frame cooperates with the rotating nut and supports the rotating nut through thread engagement; the lifting screw rod passes through the autoclave The lid of the cauldron, and the joint between the two is dynamically sealed. The lower end of the lifting screw is connected to the sample compartment for loading experimental samples. The upper end of the lifting screw is matched with the rotating nut through thread engagement, and the lifting screw can be driven by turning the rotating nut. Up and down, so as to realize the separation of molten salt and experimental samples at high temperature; the lifting ring is fixedly installed on the support frame, and cooperates with the lifting device to lift the autoclave; the upper part of the glove box is provided with a visual box that is sealed and connected to the glove box. The hoisting device is installed in the visible box; the gas circuit system is arranged outside the glove box, and communicates with the inside of the autoclave through a high-temperature-resistant pipeline for adjusting the internal pressure of the autoclave.

Further, the molten salt impregnation experiment device also includes a cooling device, which is used to prevent the joint between the lid and the body of the autoclave from being sealed at high temperature. The cooling device includes a chiller and a water cooling jacket, and the chiller is installed on a glove Outside the box, the water-cooling jacket is installed on the inner wall of the well-type atmosphere furnace intersection, and the chiller and the water-cooling jacket are connected by stainless steel water pipes to form a cooling water circulation loop.

Preferably, the dynamic sealing of the connection between the lifting screw and the autoclave lid is realized by filling flexible graphite, so that good dynamic sealing performance can be obtained.

Preferably, the lifting screw is a hollow structure with a sealed bottom, and a temperature sensing part is arranged in the hollow structure at the lower end, so that the actual temperature of the sample in the sample chamber can be monitored more accurately.

Preferably, the gas path system includes a ventilation system and a vacuum system, which can respectively pressurize and evacuate the autoclave, wherein the ventilation system includes a gas cylinder communicated with the interior of the autoclave, the gas cylinder is filled with inert gas, and the The vacuum system includes a vacuum pump in communication with the interior of the autoclave.

Due to the adoption of the above technical solution, the molten salt impregnation experimental device for carbon materials of the present invention can effectively avoid the problem of molten salt absorbing water at room temperature, and oxidation during the whole process of heating and cooling, etc., and can be convenient according to the actual application environment. Adjust the experimental air pressure flexibly, and solve the safe separation of molten salt and sample at high temperature after the experiment, thus providing conditions for more accurate testing of the molten salt infiltration amount of carbon materials, so as to develop carbon materials more scientifically Study on the infiltration characteristics of molten salt.

Description of drawings

Fig. 1 is a kind of structural schematic diagram of existing molten salt corrosion experimental device;

Fig. 2 is the overall structure schematic diagram of a preferred embodiment of the molten salt impregnation experimental device of the present invention;

Fig. 3 is the structural representation of autoclave in preferred embodiment;

Fig. 4 is a schematic structural view of the sample lifting device in a preferred embodiment;

Fig. 5 is a schematic structural view of the gas path system in a preferred embodiment;

Fig. 6 is the structural representation of cooling device in preferred embodiment;

Fig. 7 is the structural representation of pit-type atmosphere furnace in the preferred embodiment;

Fig. 8 is a schematic structural view of a glove box in a preferred embodiment;

The meanings of the symbols in the figure are as follows:

1. Autoclave, 2. Sample lifting device, 3. Gas system, 4. Cooling device, 5. Well-type atmosphere furnace, 6. Glove box, 7. Hoisting device, 101. Kettle body, 102. Kettle cover, 103 , heat-resistant steel pipe, 201, carbon material sample, 202, sample cabin, 203, lifting screw, 204, support frame, 205, rotating nut, 206, lifting ring, 207, thermocouple, 301, vacuum pump, 302, pressure gauge , 303-1～303-4, gas pipe connector, 304, pressure reducing valve, 305, gas circuit panel, 306, gas cylinder, 307, connecting pipe, 401, water cooling jacket, 402, chiller, 403, stainless steel water inlet pipe, 501. Furnace body, 502. Hearth, 503. Flange, 504. Stainless steel inlet and outlet pipes, 505. Heating wire outlet, 506. Thermocouple, 601. Main box, 602. Control panel, 603. Transition cabin, 604. Purification system, 605, visible box.

detailed description

The technical scheme of the present invention is described in detail below in conjunction with accompanying drawing:

Figure 2 shows the overall structure of a preferred embodiment of the molten salt infiltration experimental device of the present invention. As shown in FIG. 2 , the device includes an autoclave 1 , a sample lifting device 2 , a gas system 3 , a cooling device 4 , a well-type atmosphere furnace 5 , a glove box 6 and a lifting device 7 . As shown in the figure, the well-type atmosphere furnace 5 is located below the glove box 6, and its furnace mouth is embedded in the glove box 6 and is sealed and connected to the bottom plate of the glove box 6 through a flange; the autoclave 1 and the sample lifting device 2 are located inside the glove box 6; hoisting The device 7 is fixedly installed in a visible box on the glove box 6, and the visible box is sealed and connected with the glove box 6; the gas circuit system 3 is arranged outside the glove box 6, and is connected to the inside of the autoclave through a high-temperature-resistant pipeline. Connected, used to adjust the internal pressure of the autoclave 1.

FIG. 3 shows the basic structure of the autoclave 1 in this embodiment. As shown in the figure, it includes a separable kettle body 101 and a kettle cover 102 . Wherein, the flange of the kettle body 101 is designed with a groove for placing a graphite sealing ring, and the kettle cover 102 is a flat plate cover, above which the sample lifting device 2 is fixedly installed. A heat-resistant steel pipe 103 for ventilation is designed on the lid 102 of the kettle. One end of the heat-resistant steel pipe 103 leads into the kettle, and the other end is connected with the gas circuit system 3 . The kettle body 101 and the kettle cover 102 are tightly connected by main bolts and nuts uniformly distributed in the circumferential direction. The connecting part of the kettle cover 102 and the sample lifting device 2 is sealed by the design method of concave-convex grooves on the metal surface and the fastening method of bolts and nuts.

Fig. 4 has shown the basic structure of sample lifting device 2 in the present embodiment, as shown in the figure, sample lifting device 2 comprises lifting screw mandrel 203, support frame 204, rotating nut 205 and suspension ring 206; Wherein, one end of lifting screw mandrel 203 It is connected with the sample cabin 202, and the carbon material sample 201 to be tested is loaded in the sample cabin 202. The other end of the lifting screw 203 cooperates with the rotating nut 205 through thread engagement, and the rotating rotating nut 205 drives the lifting screw 203 up and down, thereby realizing the separation of the molten salt and the sample at high temperature. The lifting screw 203 in this embodiment is hollow and sealed at the bottom, and is used to place a thermocouple 207, so that the temperature of the sample chamber 202 can be measured accurately in real time. Simultaneously, the lifting screw 203 passes through the center of the autoclave lid 102, and the joint between the two is filled with flexible graphite for dynamic sealing. The support frame 204 is used to support the sample lifting device 2 , the bottom is connected with the kettle cover 102 , and the top is matched with the rotating nut 205 through thread engagement and supports the rotating nut 205 . Lifting rings 206 are fixedly mounted on both sides of the support frame 204 and cooperate with the lifting device 6 for lifting and lowering the autoclave 1 .

FIG. 5 shows the gas circuit system 3 in the preferred embodiment. As shown in the figure, it includes a vacuum pump 301 , a pressure gauge 302 , air pipe connectors 303 - 1 to 303 - 4 , a pressure reducing valve 304 and a connecting pipe 307 . Wherein the pressure gauge 302, the air pipe connector 303 and the pressure reducing valve 304 are fixedly installed on the air circuit panel 305 to facilitate installation and operation. The gas system 3 is divided into a ventilation system and a vacuum system, which can pressurize and vacuum the autoclave 1 respectively. Among them, the inert gas of the ventilation system enters the autoclave 1 from the gas cylinder 306 through the gas pipe joint 303-2, the pressure reducing valve 304, the gas pipe joint 303-3, the pressure gauge 302 and the connecting pipe 307; the vacuum system passes through the vacuum pump 301 and the gas pipe joint in sequence 303-1, the pressure gauge 302 and the connecting pipe 307 are used to evacuate the autoclave 1, and the gas pipe joint 303-4 is used for degassing the autoclave 1.

Fig. 6 shows the basic structure of the cooling device 4 in the preferred example, which is used to prevent the joint between the lid 102 and the body 101 of the autoclave 1 from sealing failure at high temperature. Including a water cooling jacket 401 and a chiller 402, the cooling device 4 also has a stainless steel water inlet pipe 403 connecting the water cooling jacket 401 and the chiller 402, so that the water cooling jacket 401 and the chiller 402 form a circulating water passage.

Fig. 7 has shown the basic structure of the well-type atmosphere furnace 5 used in the preferred embodiment, and it comprises furnace body 501, furnace 502 and flange 503, and well-type atmosphere furnace 5 also has for connecting water cooling jacket 401 and chiller 402 Stainless steel inlet and outlet pipe mouth 504, heating wire outlet 505 and thermocouple 506. Well-type atmosphere furnace 5 series cycle operation type, the shell is sealed as a whole, and the bottom cover is sealed with high-temperature silica gel pad. The flange 503 is tightly connected with the glove box 6 so that the autoclave 1 is placed in the inert atmosphere in the glove box 6 . The heating wire is led out through the side heating wire outlet 505, and the thermocouple 506 is installed at the bottom of the well-type atmosphere furnace 5 and led out of the furnace. The heating wire and the thermocouple 506 are respectively sealed with polytetrafluoroethylene to prevent the atmosphere in the furnace from communicating with the outside of the furnace.

FIG. 8 shows the basic structure of the glove box 6 used in the preferred embodiment, which includes a main box body 601 , a control panel 602 , a transition chamber 603 and a purification system 604 . The control panel 602 can control the pressure and water oxygen content in the main box 601, so that the molten salt infiltration experiment can be carried out in an inert atmosphere. The purification system 604 is used to purify the atmosphere in the main box 601 to ensure that the water oxygen content is controlled below 1ppm. In addition, the upper end of the main box 601 is provided with a visible box 605 for installing the hoisting device 7 , and the visible box 605 is sealed and connected with the main box 601 .

The concrete application process of the present invention is illustrated below by an experimental example:

In order to avoid molten salt corrosion of metals, resulting in inaccurate experimental data and to facilitate the extraction of molten salt, the molten salt infiltration experiment was carried out in a graphite crucible. Before the experiment, first raise the sample lifting device 2 to the highest position, put a certain amount of molten salt into the graphite crucible, and then place the graphite crucible in the autoclave 1 . Put the prepared carbon material sample 201 (such as graphite material, pyrolytic carbon coating material, carbon-carbon composite material, silicon carbide composite material, etc.) into the sample cabin 202, and lift the sample cabin and the sample by screwing. The device is permanently connected. After the carbon material sample 201 is installed, the autoclave 1 is tightened to start the experiment. The experimental steps are roughly as follows:

1. Vacuuming

Connect the gas system 3 to the autoclave 1, close the gas pipe connector 303-3, open the gas pipe connector 303-1 and turn on the vacuum pump 301, and vacuum the autoclave 1 (it can be pumped back and forth several times according to the experimental requirements).

2. Heating

Input temperature parameters from temperature control table or temperature control panel. In order to be more conducive to temperature control accuracy, the thermocouple 506 in the well-type atmosphere furnace 5 is set to the temperature control mode, and the thermocouple 207 in the autoclave 1 is set to the temperature display mode. Adjust the thermocouple temperature according to the experimental temperature.

3. Turn on the cooling system

Turn on the cooling device 4 while heating to cool the autoclave 1, so as to prevent the leakage of the autoclave 1 caused by the failure of the seal ring at the flange 102. Set the cooling water temperature according to the demand to ensure the cooling effect.

4. Precharge

After heating to the set temperature of the experiment, before the sample is immersed in the molten salt, the autoclave 1 is pre-charged or evacuated according to the experimental requirements. Pressurization is manually adjusted. First, close the air pipe joint 303-1, open the air pipe joints 303-2 and 303-3, open the pressure reducing valve 304 to adjust to the required pressure, and then ventilate. After adjusting to the set pressure, close the gas pipe joint 303-2, and unscrew the pressure reducing valve 304. For vacuuming, refer to step 1 above.

5. Pressurization

After the temperature is raised to the temperature required for the experiment, the sample lifting device 2 is lowered so that the carbon material sample 201 is completely immersed in the molten salt. Screw the rotating nut 205 with a wrench to drive the sample lifting device 2 down until the sample is completely submerged in the molten salt. Pressurize according to the experimental requirements, and refer to step 4 above for the pressurization step. After the pressurization is completed, close the trachea joint 303-3, so that the whole set of equipment is in an airtight state. The experiment was started and kept warm.

6. Sampling

After the experiment, the carbon material sample 201 was separated from the molten salt. Screw the rotating nut 205 with a wrench to drive the sample lifting device 2 to rise until the sample is completely separated from the molten salt, and then cool down. As the temperature drops, the air pressure in the autoclave 1 also drops. In order to avoid the influence of the pressure drop on the experimental results during the cooling process, it is necessary to keep the pressure on the autoclave 1. The specific steps are to close the trachea connector 303-1, open the trachea connectors 303-2 and 303-2, adjust the pressure reducing valve 304 to the required pressure, and then maintain the ventilation state. After cooling down to room temperature, the experiment ended.

Using the invention to carry out the molten salt impregnation experiment of the carbon material used in the molten salt reactor has the advantages of safety, reliability, high experimental precision and low experimental cost, and has good application prospects. In addition, the invention can also be used in molten salt corrosion experiments of alloy materials for molten salt reactors.

Claims (7)

1. the fused salt infiltration experimental provision of MSR carbon materials, it is characterised in that including：Autoclave, glove box, well formula gas Atmosphere stove, air-channel system, hanging apparatus, sample lowering or hoisting gear；The well formula atmosphere furnace is located at below glove box, its fire door insertion hand Casing is simultaneously tightly connected by flange and glove box bottom plate；Autoclave and sample lowering or hoisting gear are located inside glove box；The height Pressure kettle includes separable kettle and kettle cover；The sample lowering or hoisting gear include elevating screw, support frame, rotating nuts, suspension ring, Sample chamber, wherein, the bottom of support frame is fixedly connected with autoclave kettle cover, and its top passes through threaded engagement mode and rotating nuts Rotating nuts are supported with merging；Elevating screw passes through autoclave kettle cover, and both junction dynamic sealings, the lower end of elevating screw It is connected with the sample chamber for loading laboratory sample, the upper end of elevating screw is coordinated by threaded engagement mode and rotating nuts, Elevating screw oscilaltion can be driven by rotating rotating nuts, so as to realize the separation of fused salt and laboratory sample under high temperature；Hang Ring is fixedly mounted on support frame, is coordinated with hanging apparatus, for lifting autoclave；Gloves upper box part is provided with close with glove box The connected visual casing of envelope, the hanging apparatus are installed in the visual casing；The air-channel system is arranged at outside glove box, Connected by resistant to elevated temperatures pipeline with autoclave, for adjusting autoclave air pressure.

2. fused salt as claimed in claim 1 infiltrates experimental provision, it is characterised in that also including cooling device, for preventing high pressure The kettle cover of kettle and the seal failure at high temperature of kettle junction, the cooling device include cooling-water machine and water collar, cooling-water machine installation Outside glove box, water collar is installed on the well formula atmosphere furnace fire door inwall, and cooling-water machine and water collar pass through stainless steel waterpipe Connection, form cooling water circulation loop.

3. fused salt as claimed in claim 1 infiltrates experimental provision, it is characterised in that the junction of elevating screw and autoclave kettle cover Dynamic sealing realized by filling flexible graphite.

4. fused salt as claimed in claim 1 infiltrates experimental provision, it is characterised in that the elevating screw is hollow for sealed bottom Structure, temperature sensing component is provided with its lower end hollow structure.

5. fused salt as claimed in claim 4 infiltrates experimental provision, it is characterised in that the temperature sensing component is thermocouple.

6. fused salt as claimed in claim 1 infiltrates experimental provision, it is characterised in that the air-channel system includes aerating system and taken out Vacuum system, to autoclave pressurization and it can vacuumize respectively, wherein, aerating system includes the gas cylinder connected with autoclave, Filled with inert gas in gas cylinder, pumped vacuum systems includes the vavuum pump connected with autoclave.

7. fused salt as claimed in claim 1 infiltrates experimental provision, it is characterised in that also includes being used for the graphite earthenware for holding fused salt Crucible.