A visualization experimental section for studying the flow and solidification characteristics of lead-bismuth entrained metal particles

Abstract

A visualization experimental section for studying the flow and solidification characteristics of lead-bismuth entrained metal particles, which includes: inlet and outlet connecting pipes, upper and lower flanges, bolts, nuts, aluminum gaskets, fluororubber, special-shaped filters, metal particles, quartz glass tubes, indium tin oxide heating films; the inlet and outlet connecting pipes are used to connect the lead loop and provide liquid lead-bismuth alloy for the experimental section; the quartz glass tube is connected by flanges and sealed with aluminum gaskets and fluororubber; the special-shaped filter is welded at the position of the lower flange on the inlet side and is used to support the metal particles; the outer side of the quartz glass tube is coated with a transparent indium tin oxide heating film to achieve temperature control of the pipe while ensuring transparency; the present invention can obtain visualization experimental data of the flow and solidification of lead-bismuth entrained metal particles under the boundary condition of a constant-temperature wall surface, meet the research requirements for the flow and solidification characteristics of lead-bismuth entrained metal particles, have excellent sealing performance, high visualization degree, high temperature control accuracy, convenient disassembly, and at the same time meet the current processing technology requirements.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal-hydraulics of lead-based reactors, and particularly relates to a visualization experimental section for studying the flow and solidification characteristics of lead-bismuth entrained metal particles. Background Art

[0002] Lead-based reactors have good inherent safety, thermal-hydraulic characteristics, and neutron physics performance. At the same time, they have outstanding advantages in miniaturization, sustainability, and economy, and have become one of the main candidate reactor types for the fourth-generation advanced nuclear reactors. Since 1999 in China, the research on the accelerator-driven subcritical system (ADS) has been carried out. The Chinese Academy of Sciences started the "ADS Special Project" in 2011 to carry out transmutation technology research, selected the lead-based reactor as the main development direction, and proposed the CLEAR series of lead-based reactor concepts.

[0003] As a fourth-generation nuclear energy system, the safety and reliability of lead-based reactors, especially their response capabilities under severe accidents, have received extensive attention. The three major nuclear accidents in history have confirmed the possibility of severe core damage and large-scale release of radioactive substances in reactors, which has also attracted great attention from nuclear regulatory authorities to the safety analysis of reactor severe accidents. Although lead-based reactors have relatively high safety, under the triggering of initiating events such as unprotected transient overpower or unprotected undercooling, there is still a possibility of severe accidents where a large area of fuel elements fails and melts in the core. And after the fuel elements fail, during the migration process of fuel particles in the reactor, theoretically there is a possibility that the reactor returns to critical due to fuel accumulation, and the severe consequence caused by this is a sudden increase in reactor power, which may ultimately lead to the occurrence of a core meltdown accident and cause a large-scale release of radioactive substances. At present, the mechanism phenomenon of lead-bismuth entrained fuel particles during the migration process in the reactor is not clear, and there is an urgent need to carry out mechanism experimental research on their flow and solidification characteristics.

[0004] Aiming at the above problems, the existing domestic and foreign experimental section design schemes for the flow and solidification characteristics of lead-bismuth entrained metal particles have the following deficiencies: 1) Due to the opacity of lead-bismuth alloys, visualization experiments on the flow and solidification of lead-bismuth entrained metal particles often require expensive measurement equipment such as neutron radiography, and it is difficult to obtain these measurement equipment and their use qualifications; 2) The technical solutions for the connection, fixation, and sealing of quartz glass tubes are not mature, and liquid lead-bismuth is extremely easy to overflow, and quartz glass tubes are extremely easy to break; 3) It is difficult to control the wall temperature boundary of the visualization experimental section, and the accuracy is low; 4) The installation of the experimental section is complex. The above deficiencies limit the in-depth research on the flow and solidification characteristics of lead-bismuth entrained metal particles and hinder the development of lead-based reactors. Summary of the Invention

[0005] In order to overcome the problems existing in the above-mentioned prior art, the object of the present invention is to provide a visualization experimental section for studying the flow and solidification characteristics of lead-bismuth entraining metal particles, to obtain visual image data of the flow and solidification of lead-bismuth entraining metal particles, and to provide a basis for the visualization experiment of the flow and solidification of lead-bismuth entraining metal particles.

[0006] In order to achieve the above object, the present invention adopts the following technical solutions:

[0007] A visualization experimental section for studying the flow and solidification characteristics of lead-bismuth entraining metal particles, the visualization experimental section includes: an inlet connecting pipe 1, an outlet connecting pipe 2, a nut 3, a bolt 4, a lower flange 5, an upper flange 6, an aluminum gasket 7, a fluororubber 8, a special-shaped filter screen 9, metal particles 10, a quartz glass tube 11, an indium tin oxide heating film 12; the inlet connecting pipe 1 is connected to a liquid lead-bismuth source to provide a liquid lead-bismuth alloy for the experimental section; the lower flange 5 and the upper flange 6 at the inlet and outlet realize the connection of the quartz glass tube 11 with the inlet connecting pipe 1 and the outlet connecting pipe 2, are sealed with an aluminum gasket 7 and a fluororubber 8, and are fixed with a nut 3 and a bolt 4; the bottom end of the lower flange 5 at the inlet is welded and fixed to the special-shaped filter screen 9, and then welded and fixed to the inlet connecting pipe 1, and the lower flange at the outlet is directly welded and fixed to the outlet connecting pipe 2; the special-shaped filter screen 9 directly penetrates into the quartz glass tube 11 and is close to the inner wall surface of the quartz glass tube 11, and the top of the special-shaped filter screen 9 is used to support the metal particles 10 placed in the quartz glass tube 11; the indium tin oxide heating film 12 is coated on the outer wall surface of the quartz glass tube 11 to control the temperature of the outer wall surface of the quartz glass tube 11; the liquid lead-bismuth flows in from the inlet connecting pipe 1, passes through the special-shaped filter screen 9, entrains the metal particles 10 and flows upward. Due to the transparency of the quartz glass tube 11 and the indium tin oxide heating film 12, visual data of the upward movement of the lead-bismuth entraining the metal particles 10 can be obtained.

[0008] The quartz glass tube 11 is connected by the lower flange 5 and the upper flange 6, sealed with an aluminum gasket 7 and a fluororubber 8, and fixed with a nut 3 and a bolt 4. This way of assembling the quartz glass tube can effectively ensure the sealing performance between the quartz glass tube 11 and the connecting pipe, prevent the liquid lead-bismuth from overflowing from the connection; can effectively fix the position and direction of the quartz glass tube 11; can prevent the quartz glass tube 11 from cracking during the assembly process; is conducive to the disassembly of the quartz glass tube 11.

[0009] The sealing method of the aluminum gasket 7 and the fluororubber 8 is that two aluminum gaskets sandwich a fluororubber. The aluminum gasket effectively prevents the offset of the fluororubber during the fixing process, ensures that the position of the fluororubber does not shift during the extrusion process, and improves the sealing performance.

[0010] The inlet connecting pipe 1, the outlet connecting pipe 2, the nut 3, the bolt 4, the lower flange 5 and the upper flange 6 are made of stainless steel, with a temperature resistance higher than the melting point of the lead-bismuth alloy, meeting the experimental research on the flow and solidification of liquid lead-bismuth entraining metal particles below 800°C.

[0011] The transparent quartz glass tube 11 is coated with the transparent indium tin oxide heating film 12 to form a lead-bismuth flow channel, providing a visualizable flow channel. And the transparent indium tin oxide heating film 12 can precisely control the temperature of the outer wall surface of the quartz glass tube 11 through a temperature control system; the indium tin oxide heating film 12 is coated on the quartz glass tube 11 with a high-temperature resistant transparent glue.

[0012] The special-shaped filter screen 9 is used to support the metal particles 10; the special-shaped filter screen 9 is in the shape of a top hat, and the brim part is used for welding and fixing with the inlet connecting pipe 1 and the lower inlet flange 3; the body part passes through the quartz glass tube 11 and is in close contact with its inner wall surface. The height of the body should be greater than the sum of the thicknesses of the upper flange 6 and the lower flange 5 to ensure that the metal particles 10 can be supported in a transparent and visible position; the mesh number requirement of the top of the hat should be such that the metal particles 4 just cannot pass through the filter screen, but the mesh number cannot be too high to prevent the lead-bismuth from solidifying and blocking the filter screen at the top of the hat. The mesh number of the body and the brim should be much higher than that of the top of the hat to ensure that the structure of the special-shaped filter screen 9 does not deform greatly during the experiment.

[0013] The inner diameter of the quartz glass tube 11 should be greater than 5 times the equivalent diameter of the metal particles 10 to prevent the larger particles from hindering the visualization of the near-wall surface of the quartz glass.

[0014] The outer sides of the inlet connecting pipe 1, the outlet connecting pipe 2, and all flanges are coated with heating wires and heat insulation cotton to control the inlet temperature of the experimental section.

[0015] Compared with the existing experimental devices at home and abroad, the present invention has the following advantages and beneficial effects:

[0016] 1. The assembly and sealing method of the quartz glass tube can effectively prevent the quartz glass tube from cracking during the assembly process while ensuring that the liquid lead-bismuth alloy does not leak. The overall sealing performance is good and the disassembly is convenient;

[0017] 2. The use of a transparent quartz glass tube coated with a transparent indium tin oxide heating film realizes the visualization of the flow and solidification process of lead-bismuth entraining metal particles, avoiding expensive measurement equipment such as neutron radiography and the acquisition of its qualifications, and effectively reducing the experimental research cost;

[0018] 3. Using the indium tin oxide heating film as a means of heat preservation and temperature control for the quartz glass tube, combined with the temperature control system, can precisely control the temperature of the outer wall surface of the quartz glass tube on the premise of ensuring the visualization of the quartz glass tube;

[0019] 4. The specially designed special-shaped filter screen structure can effectively support metal particles and minimize the impact on the assembly and sealing of the quartz glass tube.

[0020] In summary, a visualization experimental section for studying the flow and solidification characteristics of lead-bismuth entraining metal particles according to the present invention is used to study the flow and solidification characteristics of lead-bismuth entraining metal particles. Visual experimental data on the flow and solidification of lead-bismuth entraining metal particles under the boundary condition of a constant-temperature wall surface can be obtained, meeting the research requirements for the flow and solidification characteristics of lead-bismuth entraining metal particles. It has excellent sealing performance, high visualization degree, high temperature control accuracy, is convenient to disassemble, and meets the current processing technology requirements at the same time. Brief Description of the Drawings

[0021] Figure 1 It is a structural diagram of a visualization experimental section for studying the flow and solidification characteristics of lead-bismuth entraining metal particles according to the present invention. Detailed Description of the Invention

[0022] The present invention will be further described in detail below in conjunction with the drawings and specific embodiments:

[0023] The visualization experimental section includes: an inlet connection pipe 1, an outlet connection pipe 2, nuts 3, bolts 4, a lower flange 5, an upper flange 6, an aluminum gasket 7, fluororubber 8, a special-shaped filter screen 9, metal particles 10, a quartz glass tube 11, and an indium tin oxide heating film 12.

[0024] The inlet connection pipe 1 is made of stainless steel and is connected to a 200°C liquid lead-bismuth source, providing a liquid lead-bismuth alloy with a velocity of 0.1 m / s to 1 m / s for the experimental section. The inner diameter of the experimental glass tube 11 is 14 mm, the wall thickness is 2 mm, and the tube length is 1.2 m. The connection of the quartz glass tube 11 is achieved by using a stainless steel lower flange 5 and an upper flange 6. The flange has four threaded holes evenly arranged in concentric circles with an inner diameter of 18 mm, an outer diameter of 80 mm, and a diameter of 50 mm. The thickness of the upper flange is 12 mm, the thickness of the lower flange is 24 mm, the height of the convex platform of the upper flange is 6 mm, and the depth of the groove of the lower flange is 12 mm. Sealing is achieved by using an aluminum gasket 7 and fluororubber 8. The sealing method of the aluminum gasket 7 and fluororubber 8 is that two aluminum gaskets sandwich one fluororubber. The aluminum gasket effectively prevents the offset of the fluororubber during the fixing process, ensuring that the position of the fluororubber does not shift during extrusion and improving the sealing performance. Fixing is achieved by using nuts 3 and bolts 4. During the assembly process, the four bolts are tightened simultaneously to prevent the quartz glass tube from cracking due to uneven stress. The bottom end of the lower flange 5 at the inlet is welded and fixed to the special-shaped filter screen 9, and then welded and fixed to the inlet connection pipe 1. The lower flange at the outlet is directly welded and fixed to the outlet connection pipe 2. The outlet connection pipe 2, nuts 3, bolts 4, lower flange 5, and upper flange 6 are all made of stainless steel.

[0025] The special-shaped filter screen 9 is in the shape of a top hat, made of stainless steel. The outer diameter of the hat body is 14 mm, the height of the hat body is 40 mm, the outer diameter of the brim is 18 mm, the mesh number of the hat top is 40 meshes, and the mesh number of the hat body is 80 meshes. The special-shaped filter screen 9 is directly inserted into the quartz glass tube 11 and closely adheres to the inner wall surface of the quartz glass tube 11. The top of the special-shaped filter screen 9 is used to support the metal particles 10 placed in the quartz glass tube 11. The metal particles 10 are uniform spheres with a diameter of 1 mm. The brim part is used to be welded and fixed to the inlet connecting pipe 1 and the lower flange 3 of the inlet; the hat body part passes through the quartz glass tube 11 and is in close contact with its inner wall surface.

[0026] The indium tin oxide heating film 12 is coated on the outer wall surface of the quartz glass tube 11 to control the temperature of the outer wall surface of the quartz glass tube 11; the liquid lead-bismuth flows in from the inlet connecting pipe, passes through the special-shaped filter screen 9, and entrains the metal particles 10 to flow upward. Due to the transparency of the quartz glass tube 11 and the indium tin oxide heating film 12, visual data of the upward movement of the lead-bismuth entraining the metal particles 10 can be obtained.

[0027] The transparent quartz glass tube 11 coated with the transparent indium tin oxide heating film 12 is used as the flow channel for the lead-bismuth, providing a visual flow channel, and the transparent indium tin oxide heating film 12 can precisely control the temperature of the outer wall surface of the quartz glass tube 11 through the temperature control system; the indium tin oxide heating film 12 is coated on the quartz glass tube 11 with high-temperature resistant transparent glue.

[0028] The inlet connecting pipe 1, the outlet connecting pipe 2, and the outer sides of all flanges are coated with heating wires and heat insulation cotton to control the inlet temperature of the experimental section.

[0029] The above content is a further detailed description of the present invention in combination with specific preferred embodiments. It cannot be determined that the specific embodiments of the present invention are limited to this. For those of ordinary skill in the technical field to which the present invention belongs, without departing from the concept of the present invention, several simple deductions or substitutions can still be made, which should all be regarded as belonging to the patent protection scope determined by the claims submitted by the present invention.

Claims

1. A visualization experimental section for studying the flow and solidification characteristics of lead-bismuth entrained metal particles, characterized in that: The visualization experimental section includes: an inlet connecting pipe (1), an outlet connecting pipe (2), nuts (3), bolts (4), a lower flange (5), an upper flange (6), an aluminum gasket (7), fluororubber (8), a special-shaped filter screen (9), metal particles (10), a quartz glass tube (11), and an indium tin oxide heating film (12); the inlet connecting pipe (1) is connected to a liquid lead-bismuth source to provide liquid lead-bismuth alloy for the experimental section; the lower flange (5) and the upper flange (6) at the inlet and outlet realize the connection of the quartz glass tube (11) with the inlet connecting pipe (1) and the outlet connecting pipe (2), are sealed with an aluminum gasket (7) and fluororubber (8), and are fixed with nuts (3) and bolts (4); the bottom end of the lower flange (5) at the inlet is welded and fixed to the special-shaped filter screen (9), and then welded and fixed to the inlet connecting pipe (1), and the lower flange at the outlet is directly welded and fixed to the outlet connecting pipe (2); the special-shaped filter screen (9) directly penetrates into the quartz glass tube (11) and is close to the inner wall surface of the quartz glass tube (11), and the top of the special-shaped filter screen (9) is used to support the metal particles (10) placed in the quartz glass tube (11); the indium tin oxide heating film (12) is coated on the outer wall surface of the quartz glass tube (11) to control the temperature of the outer wall surface of the quartz glass tube (11); the liquid lead-bismuth flows in from the inlet connecting pipe (1), passes through the special-shaped filter screen (9), entrains the metal particles (10) and flows upward. Due to the transparency of the quartz glass tube (11) and the indium tin oxide heating film (12), visual data of the upward movement of lead-bismuth entraining metal particles (10) can be obtained.

2. The visualization experimental section for studying the flow and solidification characteristics of lead-bismuth entrained metal particles according to claim 1, characterized in that: The quartz glass tube (11) is connected by the lower flange (5) and the upper flange (6), sealed with an aluminum gasket (7) and fluororubber (8), and fixed with nuts (3) and bolts (4). This way of assembling the quartz glass tube can effectively ensure the sealing performance between the quartz glass tube and the connecting pipe, prevent the liquid lead-bismuth alloy from overflowing from the connection, effectively fix the position and direction of the quartz glass tube (11), prevent the quartz glass tube (11) from cracking during the assembly process, and is conducive to the disassembly of the quartz glass tube (11).

3. The visualization experimental section for studying the flow and solidification characteristics of lead-bismuth entrained metal particles according to claim 1, characterized in that: The sealing method of the aluminum gasket (7) and fluororubber (8) is that two aluminum gaskets sandwich one fluororubber. The aluminum gasket effectively prevents the offset of the fluororubber during the fixing process, ensures that the position of the fluororubber does not shift during the extrusion process, and improves the sealing performance.

4. The visualization experimental section for studying the flow and solidification characteristics of lead-bismuth entrained metal particles according to claim 1, characterized in that: The inlet connecting pipe (1), the outlet connecting pipe (2), the nuts (3), the bolts (4), the lower flange (5), and the upper flange (6) are made of stainless steel, and their heat resistance is higher than the melting point of the lead-bismuth alloy, meeting the experimental research on the flow and solidification of liquid lead-bismuth entraining metal particles below 800 °C.

5. The visualization experimental section for studying the flow and solidification characteristics of lead-bismuth entrained metal particles according to claim 1, characterized in that: The transparent quartz glass tube (11) coated with the transparent indium tin oxide heating film (12) serves as the lead-bismuth flow channel, providing a visual flow channel, and the transparent indium tin oxide heating film (12) can precisely control the temperature of the outer wall surface of the quartz glass tube (11) through a temperature control system; the indium tin oxide heating film (12) is coated on the quartz glass tube (11) with a high-temperature resistant transparent glue.

6. The visualization experimental section for studying the flow and solidification characteristics of lead-bismuth entrained metal particles according to claim 1, characterized in that: An irregular-shaped filter screen (9) is used to support metal particles (10); the irregular-shaped filter screen (9) is in the shape of a top hat, and the brim part is used for welding and fixing with the inlet connecting pipe (1) and the lower flange of the inlet (5); the body part passes through the quartz glass tube (11) and is in close contact with its inner wall surface. The height of the body should be greater than the sum of the thicknesses of the upper flange (6) and the lower flange (5) to ensure that the metal particles (10) can be supported in a transparent and visible position; the mesh number requirement of the hat top should meet the condition that the metal particles (10) just cannot pass through the filter screen to prevent the lead-bismuth solidification from blocking the filter screen at the hat top. The mesh numbers of the body and the brim should be greater than or equal to 5 times the mesh number of the hat top to ensure that the structure of the irregular-shaped filter screen (9) does not deform during the experiment.

7. The visualization experimental section for studying the flow and solidification characteristics of lead-bismuth entrained metal particles according to claim 1, characterized in that: The inner diameter of the quartz glass tube (11) should be greater than 5 times the equivalent diameter of the metal particles (10) to prevent the metal particles from hindering the visualization of the near-wall surface of the quartz glass.

8. The visualization experimental section for studying the flow and solidification characteristics of lead-bismuth entrained metal particles according to claim 1, characterized in that: The inlet connecting pipe (1), the outlet connecting pipe (2), and the outer sides of all flanges are covered with heating wires and heat insulation cotton to control the inlet temperature of the experimental section.

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