Double-layer glass metal sealing medium-voltage electrical penetration assembly and preparation method thereof

Abstract

The invention belongs to the technical field of nuclear reaction safety, and particularly relates to a double-layer glass metal sealing medium-voltage electrical penetration assembly which comprises a first flange and a second flange which are in sealed butt joint. At least one first metal inner pipe is arranged on the first flange in a penetrating manner, and the first metal inner pipe is hermetically connected and fixed through sealing glass; the second flange is hermetically connected with a second metal inner tube corresponding to the first metal inner tube through sealing glass; the two ends of the first metal inner pipe and the two ends of the second metal inner pipe are provided with threaded holes which are not communicated. The opposite ends of the first metal inner pipe and the second metal inner pipe are connected through a plug-in assembly. The electrical penetration assembly has good insulation, sealing and high-voltage-resistant capabilities, also has good electrifying capability, still has extremely high sealing performance after undergoing a short-circuit damage test, and completely accords with technical indexes of nuclear power penetration assemblies.

Description

Technical Field

[0001] The invention belongs to the technical field of nuclear reaction safety, and in particular relates to a double-glazed metal-sealed medium-voltage electrical penetration component and a preparation method thereof. Background Art

[0002] Electrical penetrations are special electrical equipment installed on the reactor containment wall for cables to pass through the containment. Under normal and various accident conditions, including earthquakes and loss of coolant accidents, electrical penetrations should be able to ensure the integrity of the reactor containment, prevent the leakage of radioactive materials, and maintain the continuity of electricity and signals inside and outside the containment.

[0003] At present, most of the sealing materials for electrical penetrations are made of polymer materials for sealing. However, organic materials are prone to aging phenomena such as embrittlement and creep during long-term operation and life extension operation, and there is a risk of losing sealing and insulation functions.

[0004] In order to solve the above problems, it has become a new trend to use inorganic glass materials instead of the original organic polymer materials. However, due to the large difference in the thermal expansion coefficient of copper conductors and glass materials, there is currently no mature glass-sealed copper technology. Therefore, the mature glass-sealed Kovar alloy technology is selected to ensure the high requirements of electrical penetrations for airtightness.

[0005] However, the electrical conductivity of Kovar alloy is far inferior to that of copper conductors, and the contact resistance in the actual connection process is affected by factors such as contact method, contact area, and contact surface roughness. When large current is passed, the conductor generates too much heat, which is not conducive to long-term stable operation.

[0006] Chinese patent application 202210088324.X discloses an electrical penetration and a preparation method thereof, which first seals the cylinder with sealing glass, and then seals the cylinder with the copper guide pin by mechanical cooperation. The electrical performance is improved, but the sealing reliability is low and the sealing strength is not too high. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide a double-layer glass metal sealed medium-voltage electrical penetration and a preparation method. Through the wiring method of the metal inner tube threaded connection of the Kovar alloy, the actual flow length of the Kovar alloy can be effectively shortened, the contact resistance is greatly reduced, and the problem of excessive heat generation of the Kovar alloy when passing large current is solved; the sealing flange assembly is connected to the double-layer glass to improve the sealing strength of the electrical penetration; the metal inner tube is connected through the plug-in assembly to achieve the transfer connection, which solves the electrical performance defects of the Kovar alloy as a conductor; at the same time, the structure has a double-layer sealing end face, which further improves the reliability of the penetration.

[0008] In order to solve the above technical problems, the technical solution provided by the present invention is a double-layer glass metal sealed medium-voltage electrical penetration part, including two sealed butt-jointed first flanges and second flanges; at least one first metal inner tube is passed through the first flange, and the first metal inner tube is sealed and fixed by sealing glass; a second metal inner tube corresponding to the first metal inner tube is sealed and connected to the second flange by sealing glass; unconnected threaded holes are respectively opened at both ends of the first metal inner tube and the second metal inner tube; the first metal inner tube and the second metal inner tube are connected at one end by a plug-in assembly.

[0009] Preferably, the plug-in assembly comprises a metal socket and a metal pin, one end of the metal socket and the metal pin are respectively threadedly connected in the threaded holes at one end opposite to the first metal inner tube and the second metal inner tube; the other ends of the metal socket and the metal pin are plug-connected.

[0010] Preferably, a crown spring for connecting the metal pin is arranged in the metal socket.

[0011] Preferably, the crown spring is made of beryllium bronze or tin bronze.

[0012] Preferably, the first flange and the second flange are made of 304 stainless steel, 316L stainless steel or high-temperature nickel-based alloy; the metal pin is made of 4J29, 4J42 or 4J50 Kovar alloy material, and the outer diameter of the metal pin is 15-50mm; the plug-in component is made of copper or copper alloy material.

[0013] Preferably, a space for the plug-in assembly to dock is provided on the docking surfaces of the first flange and the second flange.

[0014] Preferably, at least one circle of metal sealing is provided at the butt joint surfaces of the first flange and the second flange on the outsides of the first metal inner tube and the second metal inner tube.

[0015] Preferably, the metal seal is oxygen-free copper silver-plated material.

[0016] Preferably, the first flange and the second flange are sealed and connected by bolts.

[0017] The present invention also provides a method for preparing a double-layer glass metal sealed medium-voltage electrical penetration, comprising the following steps:

[0018] (1) positioning the first flange and the sealing glass blank connected thereto, the first metal pin, and the second flange and the sealing glass blank connected thereto, and the second metal inner tube, respectively, and sintering and sealing them;

[0019] (2) Assembling the metal socket and the metal pin in the corresponding first metal inner tube and the second metal inner tube respectively;

[0020] (3) placing a metal seal on the butt joint surface of the first flange and the second flange; butt-jointing and sealing the assembled first flange and the second flange so that the metal pins are inserted into the corresponding metal sockets; and tightening and sealing the connection by bolts.

[0021] The present invention first performs glass-to-metal sealing on the metal flange and the threaded metal inner tube, and then splices them together by switching and plugging together through a plug-in assembly. The wiring method of the threaded connection of the metal inner tube of Kovar alloy can effectively shorten the actual flow length of the Kovar alloy, greatly reduce the contact resistance, and solve the problem of excessive heat generation of the Kovar alloy when passing a large current; the butt-plugged sealing flange assembly realizes double-layer glass sealing, which improves the sealing strength of the electrical penetration; the switching connection of the metal inner tube is realized by the plug-in assembly, which solves the electrical performance defects of the Kovar alloy as a conductor; at the same time, the structure has a double-layer sealing end face, which further improves the reliability of the penetration.

[0022] The present invention has a simple structure, realizes double-layer sealing, and has good electrical performance on the basis of high temperature resistance, high radiation and high stability. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is a cross-sectional view of a double-glazed metal-sealed medium-voltage electrical penetration.

[0024] Figure 2 It is a schematic diagram of the internal connection of double-glazed metal-sealed medium-voltage electrical penetrations. DETAILED DESCRIPTION

[0025] For a better understanding of the present invention, the following examples are further explanations of the present invention, but the content of the present invention is not limited to the following embodiments.

[0026] The double-glazed metal-sealed medium-voltage electrical penetration of the present invention is shown in FIG. Figure 1, including two sealed butt-jointed first flanges 1 and second flanges 9, the first flanges 1 and the second flanges 9 are made of 304 stainless steel, 316L stainless steel or other high-temperature nickel-based alloys. The second flange 9 should be thicker than the first flange 1. At least one through-hole 11 is provided on the first flange 1, and a first metal inner tube 31 is passed through the through-hole 11. The first metal inner tube 31 is sealed and connected to the through-hole 11 through the sealing glass 2. The surface of the sealing glass is 5-10mm away from the outer end face of the first flange, and can be used to fill silicone grease or epoxy resin to protect the glass from moisture. At least one through-hole 91 is provided on the second flange 9, and a second metal inner tube 32 is passed through the through-hole 91. The second metal inner tube 32 is sealed and connected to the through-hole 91 through the sealing glass 2. The surface of the sealing glass is 5-10mm away from the outer end face of the second flange, and can be used to fill silicone grease or epoxy resin to protect the glass from moisture. The first metal inner tube 31 on the first flange 1 and the second metal inner tube 32 on the second flange 9 are arranged one by one. The first metal inner tube 31 and the second metal inner tube 32 are made of 4J29, 4J42 or 4J50 Kovar alloy material, and the outer diameter of the metal inner tube is 15-50 mm.

[0027] The first metal inner tube 31 and the second metal inner tube 32 have the same structure, and are provided with unconnected threaded holes (311, 322) at both ends, and the threads are fine pitch threads. In order to facilitate the connection of the metal inner tubes on the first flange 1 and the second flange 9, an installation space 92 is provided on the mating surface of the second flange 9.

[0028] At least one sealing groove is provided on the mating surface of the second flange 9 outside the second metal inner tube 32, in which a metal seal 7 is arranged. The metal seal 7 is made of oxygen-free copper silver-plated material. In this example, the metal seal 7 is a metal sealing ring.

[0029] A threaded through hole 12 is provided on the first flange 1 outside the sealing groove, and a corresponding countersunk through hole 93 is provided on the second flange 9. Bolts 8 are inserted into the countersunk through hole 93 and the threaded through hole 12, and are threadedly connected with the threaded through hole 12, so as to realize a compression and sealing connection between the first flange 1 and the second flange 9.

[0030] Plug components, see Figure 1 and Figure 2 , including a metal socket 4 and a metal pin 6 that are plugged into each other, both of which are made of copper or copper alloy. The outer periphery of the metal socket 4 connected to the threaded hole of the first metal inner tube 31 is provided with a matching fine thread, and the metal socket 4 can be screwed into the threaded hole of the first metal inner tube through the threaded connection. The other end of the metal socket 4 is a socket, in which a crown spring 5 is arranged, and the crown spring sheet of the crown spring 5 is made of beryllium bronze or tin bronze.

[0031] The outer periphery of the metal pin 6, which is connected to the threaded hole of the second metal inner tube 32, is provided with a fine pitch thread matching therewith. Through the threaded connection, the metal pin 6 can be screwed into the threaded hole of the second metal inner tube. The other end of the metal pin 6 can be inserted into the crown spring 5 in the socket of the metal socket 4, and the metal pin 6 is tightly connected to the socket of the metal socket 4 through the crown spring 5. Through the insertion of the metal socket 4 and the metal pin 6, the first metal inner tube and the second metal inner tube can be transferred and connected. Because it is a threaded connection, and a fine pitch threaded connection, the connection tightness is good.

[0032] The other ends of the first metal inner tube 4 and the second metal inner tube 6 can be conductively connected to an external device through a threaded metal socket 4, a metal pin 6, or a plug-in assembly of the metal socket 4 and the metal pin 6 as an adapter.

[0033] Preparation method of the above electrical penetration piece:

[0034] (1): First, the first flange 1, the second flange 9, the metal inner tube (31, 32), the metal socket 4, and the metal pin 6 obtained by machining are cleaned and dried, and then the cleaned and dried metal inner tube 3 is placed in an atmosphere furnace for pre-oxidation treatment. The glass raw powder is melted, ball-milled, pulped, granulated, pressed, debonded and vitrified to obtain a glass blank 2. The obtained glass blank 2, the first metal inner tube 31 and the first flange 1, the glass blank 2, the second metal inner tube 32, and the second flange 9 are positioned by sintering molds and placed in an atmosphere sintering furnace for sealing. The sintering mold is made of graphite material and the sealing temperature is 960-1040°C. The first metal inner tube is sealed and connected to the first flange 1 by sealing glass to obtain a first sealing flange, and the second metal inner tube is sealed and connected to the second flange 9 by sealing glass 2 to obtain a second sealing flange. The first sealing flange and the second sealing flange are pickled to remove the oxide scale on the surface of the flange and the metal inner tube. In this process, the graphite remaining on the surface of the sealing glass can be removed at the same time. Finally, the first sealing flange and the second sealing flange are cleaned and dried.

[0035] The first sealing flange and the second sealing flange after cleaning and drying are electroplated, and a nickel layer of 2 to 3 um and a gold layer of 0.5 to 1.27 um are plated on the surface of the metal inner tube in sequence.

[0036] (2): The threaded ends of the metal socket 4 and the metal pin 6 are screwed into the threaded holes of the metal inner tubes (31, 32) in the first sealing flange and the second sealing flange respectively, and the matching threads are fine pitch threads, which is beneficial to reduce contact resistance. A crown spring 5 is arranged in the metal socket.

[0037] (3): A metal seal 7 is placed in the sealing groove of the second flange 9, and then the first sealing flange and the second sealing flange are guided and plugged together, and the metal pin 6 is inserted into the metal socket 4. After the plugging is completed, the first sealing flange and the second sealing flange are compressed and sealed with bolts 8.

[0038] Six specifications of metal inner tubes were selected to make six specifications of electrical penetration parts. The outer diameters of the metal inner tubes were 22mm, 24mm, 26mm, 28mm, 30mm, and 32mm, respectively, and the corresponding inner diameters of the penetration channels were 33mm, 35mm, 37mm, 39mm, 41mm, and 43mm, respectively.

[0039] The electrical properties of 6 types of gold electrical penetrations were tested respectively, and the test results are shown in Table 1.

[0040] Table 1

[0041] Electrical penetrations Insulation resistance(Ω) <![CDATA[Leakage rate (Pa·m 3 / s)]]> Pressure bearing capacity Dielectric strength (5kv / min) 1 <![CDATA[1.5×10 12 ]]> <![CDATA[≤1.0×10 -12 ]]> ≥40MPa No breakdown 2 <![CDATA[9.8×10 11 ]]> <![CDATA[≤1.0×10 -12 ]]> ≥40MPa No breakdown 3 <![CDATA[6.7×10 11 ]]> <![CDATA[≤1.0×10 -12 ]]> ≥40MPa No breakdown 4 <![CDATA[1.2×10 12 ]]> <![CDATA[≤1.0×10 -12 ]]> ≥40MPa No breakdown 5 <![CDATA[3.3×10 11 ]]> <![CDATA[≤1.0×10 -12 ]]> ≥40MPa No breakdown 6 <![CDATA[6.9×10 11 ]]> <![CDATA[≤1.0×10 -12 ]]> ≥40MPa No breakdown

[0042] The rated continuous current stable temperature rise test and short-circuit heat capacity test were carried out on 6 types of electrical penetration parts. The test parameters were: rated continuous current: 300A; short-circuit current: 24kA / 0.3s; peak value: 50kA. Table 2 shows the temperature rise data after the test and the leakage rate test. The test temperature point is the metal pin.

[0043] Table 2

[0044]

[0045]

[0046] It can be seen from Table 1 and Table 2 that the 6 specifications of electrical penetrations prepared by the above method all have good insulation, sealing, high voltage resistance, and good power-carrying capacity. They still have extremely high sealing performance after undergoing a short-circuit destruction test, and fully meet the technical indicators of nuclear power penetrations.

Claims

1. A double-glazed metal-sealed medium-voltage electrical penetration, characterized in that: It comprises two sealing butt-jointed first flanges and second flanges; at least one first metal inner tube is passed through the first flange, and the first metal inner tube is fixed by sealing glass; a second metal inner tube corresponding to the first metal inner tube is sealed and connected to the second flange by sealing glass; both ends of the first metal inner tube and the second metal inner tube are respectively provided with unconnected threaded holes; the first metal inner tube and the second metal inner tube are connected at opposite ends by a plug-in assembly.

2. The double-glazed metal-sealed medium-voltage electrical penetration according to claim 1, characterized in that: The plug-in assembly includes a metal socket and a metal pin, one end of the metal socket and the metal pin are respectively threadedly connected in the threaded holes at one end opposite to the first metal inner tube and the second metal inner tube; the other ends of the metal socket and the metal pin are plug-connected.

3. The double-glazed metal-sealed medium-voltage electrical penetration according to claim 2, characterized in that: A crown spring for connecting the metal pin is arranged in the metal socket.

4. The double-glazed metal-sealed medium-voltage electrical penetration according to claim 3, characterized in that: The crown spring is made of beryllium bronze or tin bronze.

5. The double-glazed metal-sealed medium-voltage electrical penetration according to claim 1, characterized in that: The first flange and the second flange are made of 304 stainless steel, 316L stainless steel or high-temperature nickel-based alloy; the metal pin is made of 4J29, 4J42 or 4J50 Kovar alloy material, and the outer diameter of the metal pin is 15-50mm; the plug-in component is made of copper or copper alloy material.

6. The double-glazed metal-sealed medium-voltage electrical penetration according to claim 1, characterized in that: A space for the plug-in assembly to dock is provided on the docking surfaces of the first flange and the second flange.

7. The double-glazed metal-sealed medium-voltage electrical penetration according to claim 1, characterized in that: At least one circle of metal sealing is arranged at the butt joint surfaces of the first flange and the second flange on the outer sides of the first metal inner tube and the second metal inner tube.

8. The double-glazed metal-sealed medium-voltage electrical penetration according to claim 7, characterized in that: The metal seal is made of oxygen-free copper plated with silver.

9. The double-glazed metal-sealed medium-voltage electrical penetration according to claim 1, characterized in that: The first flange and the second flange are sealed and connected by bolts.

10. The method for preparing the double-glazed metal-sealed medium-voltage electrical penetration according to any one of claims 1 to 9, comprising the following steps: (1) positioning the first flange and the sealing glass blank connected thereto, the first metal pin, and the second flange and the sealing glass blank connected thereto, and the second metal inner tube, respectively, and sintering and sealing them; (2) Assembling the metal socket and the metal pin in the corresponding first metal inner tube and the second metal inner tube respectively; (3) placing a metal seal on the butt joint surface of the first flange and the second flange; butting and sealing the assembled first flange and the second flange, and inserting the metal pin into the corresponding metal socket; The connection is sealed by tightening the bolts.

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