Glass-metal sealing low-voltage instrument electrical penetration assembly for LNG (Liquefied Natural Gas)

Abstract

The invention discloses a glass-metal sealing low-voltage instrument electrical penetration assembly for LNG (Liquefied Natural Gas), metal conductors are respectively in sealing insulation connection with a first flange and a second flange through sealing glass, the metal conductors are electrically connected through metal jacks, and the first flange and the second flange are mechanically sealed through a fastening nut and a metal sealing gasket. A cavity is reserved in the second flange, a mounting groove is formed in the end face, a mounting threaded hole is formed in the top, a metal sealing gasket is arranged on the mounting groove, and a plug component or a pressure gauge is mounted in the mounting threaded hole. According to the low-pressure instrument penetration piece, the low-temperature pressure-bearing performance, the sealing and insulating performance and the high-temperature-resistant performance of the low-pressure instrument penetration piece are all remarkably improved, meanwhile, compared with an organic sealing material, the inorganic glass sealing material has the advantages of being stable in physicochemical property and free of aging, and the service life of the low-pressure instrument penetration piece product can be remarkably prolonged.

Description

Technical Field

[0001] The invention relates to the technical field of electrical equipment, and in particular to a glass-metal sealed low-pressure instrument electrical penetration piece for LNG. Background Art

[0002] Natural gas can be liquefied at -165℃ to form liquid natural gas (LNG for short). Due to the characteristics of low temperature, flammability, explosion and easy vaporization, LNG needs to be stored and transported in cryogenic tanks and loaded and unloaded by cryogenic submersible pumps. In order to more safely supply power and transmit signals to cryogenic submersible pumps, special low-voltage instrument electrical penetrations are required. This component must ensure the integrity of the pressure vessel on the basis of achieving electrical connection, that is, a highly reliable sealing function to prevent gas leakage. Once gas leaks, it will cause serious damage to LNG storage and transportation equipment such as LNG storage tanks, LNG transport ships, and LNG receiving stations. Therefore, as an electrical equipment to ensure safety and performance in the LNG field, the stable and reliable operation of low-voltage instrument electrical penetrations for LNG is very critical.

[0003] The existing low-voltage instrument electrical penetrations in China mainly use organic materials for sealing and insulating connections between flanges and conductors. For example, the utility model with application number CN201621134868.1 discloses an ultra-low temperature low-voltage electrical penetration, including a spinning assembly, a sealing nut, a guide ring, a sealing ring, a first flange and a second flange; multiple fillers are arranged between the insulating sleeve and the stainless steel pipe; the insulating sleeve and the filler are made of polytetrafluoroethylene. Organic materials are at risk of aging in long-term normal temperature and high temperature service environments, and the organic materials and metals are bonded by van der Waals forces, with low bond energy and insufficient bonding, and there is a risk of sealing failure during long-term operation. At the same time, when used in a low-temperature environment, organic materials will become brittle, which will significantly reduce the sealing performance, electrical performance and pressure-bearing performance of the electrical penetrations, and cannot meet the requirements for long-term use in an extremely low temperature environment of -196°C. Summary of the invention

[0004] In view of the deficiencies of the prior art, the purpose of the present invention is to provide a glass-metal sealed low-pressure instrument electrical penetration for LNG. By using inorganic glass materials for sealing and insulating connection between flanges and metal conductors, the electrical penetration can meet high sealing and high pressure resistance in an extremely low temperature environment of -196°C, while also ensuring normal electrical signal transmission functions. Inorganic glass sealing materials are used, which are chemically bonded to metals, with a bond energy of 120 to 800 KJ / mol, much higher than the van der Waals force bonding between the original organic materials and metals. Its low-temperature pressure bearing performance, sealing insulation performance, and high-temperature resistance performance are significantly improved. At the same time, compared with organic sealing materials, inorganic glass sealing materials have the characteristics of stable physical and chemical properties, no aging, and no brittleness. They can meet the long-term use in extremely low temperature environments while significantly improving the service life of low-voltage instrument electrical penetrations.

[0005] The technical solution adopted by the present invention to solve the technical problem is: a glass-metal sealed low-pressure instrument electrical penetration part for LNG, including a first flange, a second flange, a metal conductor, a metal socket, a sealing glass, a metal sealing gasket, a mounting threaded hole, and a fastening nut; a plurality of sealing holes are provided on the first flange and the second flange, and the specifications and depths of the sealing holes opened in the first flange and the second flange are consistent; the sealing glass and the corresponding metal conductor are high-temperature sintered and sealed and insulated in the sealing hole; the first flange and the second flange are mechanically sealed and connected through the fastening nut; a cavity is left inside the second flange, and the metal conductors encapsulated in the first flange and the second flange are electrically connected in the cavity through the metal socket; a mounting groove is provided on the end face of the second flange, and a metal sealing gasket is provided in the mounting groove; a mounting threaded hole is provided on the second flange.

[0006] Furthermore, the sealing holes on the first flange and the second flange have the same pattern, and the specifications and depths of the sealing holes are consistent; sealing glass and metal conductors are placed in the sealing holes, and then the flanges and the metal conductors are formed into a whole through high-temperature sintering, thereby achieving a sealed and insulating connection.

[0007] Furthermore, the end faces of the first flange and the second flange are provided with threaded holes at the same position, the number of the threaded holes is at least 6 and is symmetrically distributed; the fastening nuts are installed in the threaded holes on the end faces of the first flange and the second flange, and mechanical sealing is performed through threads.

[0008] Furthermore, the specific steps of sealing and insulatingly connecting the first flange and the second flange with the corresponding metal conductor through sealing glass are as follows:

[0009] 1) Assemble the first flange or the second flange, the sealing glass, and the metal conductor together through a graphite fixture;

[0010] 2) The assembled whole is placed in a nitrogen atmosphere sintering furnace at 870-930°C, and the high temperature sintering time is controlled at 15-25 minutes;

[0011] 3) The sintered electrical penetration parts are surface treated to make the flange surface clean and bright, with no oxide layer remaining on the surface;

[0012] 4) Conductor gold plating is performed on the electrical penetration components with surface treatment.

[0013] Furthermore, in the first flange, the outer surfaces of both ends of the sealing glass are filled with elastic sealant to protect the sealing glass from corrosion by water vapor and acid-base gases; and an insulating sleeve 1 is installed at both ends of the sealing glass, and the insulating sleeve 1 is solidified into a whole through the elastic sealant; the material of the insulating sleeve 1 is polytetrafluoroethylene or polyetheretherketone.

[0014] Furthermore, in the second flange, the outer surfaces of both ends of the sealing glass are filled with elastic sealant to protect the sealing glass from corrosion by water vapor and acid-base gases; and an insulating sleeve 1 is installed at the outer end of the sealing glass, and the insulating sleeve 1 is solidified into a whole through the elastic sealant; the material of the insulating sleeve 1 is polytetrafluoroethylene or polyetheretherketone.

[0015] Furthermore, the metal socket is inserted into the metal conductor inside the second flange, the length of the metal socket is greater than the length of the metal conductor exposed outside the second flange, and the metal socket forms an electrical connection with the metal conductor after the first flange and the second flange are mechanically sealed.

[0016] Furthermore, the metal socket is covered with an insulating sleeve 2, the length of which is greater than that of the metal socket; the insulating sleeve 2 simultaneously covers the insulating sleeve 1 on the inner surface of the first flange sealing glass; both ends of the insulating sleeve 2 are fixed by elastic sealant.

[0017] Furthermore, the metal socket has a double-ended wire spring structure inside, the metal socket is made of beryllium copper or tin bronze, the surface of the metal socket is silver-plated, the metal socket and the metal conductor are tightly fitted, and the pull-out force is between 30 and 60N.

[0018] Furthermore, the first flange and the second flange are made of 304 stainless steel, and the metal conductor is made of Kovar alloy; the expansion coefficient of the sealing glass is between 90 and 100×10 -7 / K.

[0019] Furthermore, the installation groove is provided on the assembly surface of the second flange, and the opening position is 30 to 50 mm from the sealing hole farthest from the center of the circle.

[0020] Furthermore, the metal sealing gasket is a metal O-ring or a metal C-ring.

[0021] Furthermore, the mounting threaded hole is used to install a plug component or a pressure gauge.

[0022] Furthermore, the rated voltage of the electrical penetration piece is 28V and the rated current is 4A.

[0023] The beneficial effects of the present invention are as follows: compared with the prior art, the glass-metal sealed low-pressure instrument electrical penetration for LNG provided by the present invention has the following advantages:

[0024] a. Use inorganic glass materials for sealing and insulating connection between flange and conductor, so that the electrical penetration can meet high sealing and high pressure resistance in the extremely low temperature environment of -196℃, and at the same time ensure the normal electrical signal transmission function;

[0025] b. Both double-layer flanges adopt glass-metal sealing structure and have a cavity inside for inflation. The sealing performance of electrical penetrations can be monitored in real time through a pressure gauge, which greatly improves the sealing level and safety margin of electrical penetrations;

[0026] c. A metal sealing gasket plus a fastening nut is used between the double-layer flanges for mechanical sealing. Compared with organic material O-rings, metal sealing gaskets have better tolerance to harsh environments and can meet the mechanical sealing performance under long-term use in extremely low temperature environments. It is also easy to maintain and replace parts.

[0027] d. The overall technical solution can ensure that the electrical penetrations have a highly reliable sealing function in an extremely low temperature environment of -196°C, withstand a pressure of no less than 7.5MPa, and maintain electrical connection and signal transmission functions. At the same time, compared with organic sealing materials, inorganic glass sealing materials have the characteristics of stable physical and chemical properties and no aging, which can significantly improve the service life of low-voltage instrument penetration products. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Figure 1 It is a schematic structural diagram of the electrical penetration piece of a low-voltage instrument of the present invention.

[0029] Figure 2 It is a structural cross-sectional view of the electrical penetration piece of a low-voltage instrument of the present invention.

[0030] Figure 3 It is a top view of the end surface of the low-voltage instrument electrical penetration piece of the present invention.

[0031] Among them, 1-first flange, 2-second flange, 3-metal conductor, 4-sealing glass, 5-insulating sleeve 1, 6-elastic sealant, 7-metal jack, 8-insulating sleeve 2, 9-metal sealing gasket, 10, 11-installation threaded holes; 12-fastening nut. DETAILED DESCRIPTION

[0032] The present invention is further described below by specific examples. However, these examples are only used to illustrate the present invention and are not used to limit the scope of the present invention. The directional words involved in the present invention, such as up, down, left, right, front, back, top, bottom, etc., are only used to assist understanding and are not used to limit the technical solution of the present invention.

[0033] The present invention provides a glass-metal sealed low-pressure instrument electrical penetration for LNG, see Figures 1 to 3 , including a first flange 1, a second flange 2, a metal conductor 3, a sealing glass 4, an insulating sleeve 1 5, an elastic sealant 6, a metal jack 7, an insulating sleeve 2 8, a metal sealing gasket 9, mounting threaded holes 10 and 11, and a fastening nut 12.

[0034] The first flange 1 and the second flange 2 are provided with a plurality of sealing holes, and the specifications and depths of the sealing holes opened in the first flange 1 and the second flange 2 are consistent; the sealing glass 4 and the corresponding metal conductor 3 are sealed and insulated by high-temperature sintering in the sealing holes; the first flange 1 and the second flange 2 are mechanically sealed and connected through the fastening nut 12; a cavity is reserved inside the second flange 2, and the metal conductors 3 encapsulated in the first flange 1 and the second flange 2 are electrically connected in the cavity through the metal socket 7; an installation groove is opened on the end face of the second flange 2, and a metal sealing gasket 9 is arranged in the installation groove; and the second flange 2 is provided with installation threaded holes 10 and 11.

[0035] The end faces of the first flange 1 and the second flange 2 are provided with threaded holes at the same position, and the number of threaded holes is at least 6 and is symmetrically distributed; the fastening nut 12 is installed in the threaded holes on the end faces of the first flange 1 and the second flange 2, and mechanical sealing is performed through threads.

[0036] Example 1

[0037] The metal conductor 3 is connected to the first flange 1 by sealing and insulating it through the sealing glass 4. The operation steps are as follows:

[0038] 1) Assemble the first flange 1, the sealing glass 4, and the metal conductor 3 together through a graphite fixture;

[0039] 2) The assembled whole is placed in a nitrogen atmosphere sintering furnace at 880°C, and the high-temperature sintering time is controlled within 20 minutes;

[0040] 3) The sintered electrical penetration parts are surface treated to make the metal flange surface clean and bright, with no oxide layer remaining on the surface;

[0041] 4) Conductor gold plating is performed on the electrical penetration components with surface treatment.

[0042] The metal conductor 3 is connected to the second flange 2 by sealing and insulating through the sealing glass 4. The operation steps are as follows:

[0043] 1) Assemble the second flange 2, the sealing glass 4, and the metal conductor 3 together through a graphite fixture;

[0044] 2) The assembled whole is placed in a nitrogen atmosphere sintering furnace at 880°C, and the high-temperature sintering time is controlled within 20 minutes;

[0045] 3) The sintered electrical penetration parts are surface treated to make the metal flange surface clean and bright, with no oxide layer remaining on the surface;

[0046] 4) Conductor gold plating is performed on the electrical penetration components with surface treatment.

[0047] The surfaces of all the sealing glasses 4 are filled with elastic sealant 6. The elastic sealant 6 used in this embodiment is silicone rubber. A polytetrafluoroethylene insulating sleeve 5 is placed and cured together with the silicone rubber to form a whole.

[0048] After curing, the metal conductors 3 of the first flange 1 and the second flange 2 are connected by trial plugging through the metal socket 7 to ensure that the pull-out force is above 40N. At the same time, a metal sealing gasket 9 is placed in the installation groove of the second flange 2. The metal sealing gasket 9 used in this embodiment is a metal O-ring. A polytetrafluoroethylene insulating sleeve 8 is placed outside the metal socket 7 to ensure that the polytetrafluoroethylene insulating sleeve 8 can completely cover the metal socket 7 after plugging.

[0049] Mechanical sealing is performed between the flanges through six fastening nuts 12, and the fastening torque is maintained above 200N. Finally, a pressure gauge is installed in the mounting threaded hole 10 at the top of the second flange 2, and a plug component is installed in the mounting threaded hole 11.

[0050] Example 2

[0051] The metal conductor 3 is connected to the first flange 1 by sealing and insulating it through the sealing glass 4, and the steps are as follows:

[0052] 1) Assemble the first flange 1, the sealing glass 4, and the metal conductor 3 together through a graphite fixture;

[0053] 2) The assembled whole is placed in a nitrogen atmosphere sintering furnace at 900°C, and the high temperature sintering time is controlled within 15 minutes;

[0054] 3) The sintered electrical penetration parts are surface treated to make the metal flange surface clean and bright, with no oxide layer remaining on the surface;

[0055] 4) Conductor gold plating is performed on the electrical penetration components with surface treatment.

[0056] The metal conductor 3 is connected to the second flange 2 by sealing and insulating through the sealing glass 4, and the steps are as follows:

[0057] 1) Assemble the second flange 2, the sealing glass 4, and the metal conductor 3 together through a graphite fixture;

[0058] 2) The assembled whole is placed in a nitrogen atmosphere sintering furnace at 900°C, and the high temperature sintering time is controlled within 15 minutes;

[0059] 3) The sintered electrical penetration parts are surface treated to make the metal flange surface clean and bright, with no oxide layer remaining on the surface;

[0060] 4) Conductor gold plating is performed on the electrical penetration components with surface treatment.

[0061] The surfaces of all the sealing glasses 4 are filled with elastic sealant 6. The elastic sealant 6 in this embodiment is made of silicone rubber, and a polyetheretherketone insulating sleeve 5 is placed and cured together with the silicone rubber to form a whole.

[0062] After curing, the metal conductors 3 of the first flange 1 and the second flange 2 are connected by trial plugging through the metal socket 7 to ensure that the pull-out force is above 35N. At the same time, a metal sealing gasket 9 is placed in the installation groove of the second flange 2. The metal sealing gasket 9 used in this embodiment is a metal C ring. A polyetheretherketone insulating sleeve 8 is placed outside the metal socket 7 to ensure that the polyetheretherketone insulating sleeve 8 can completely cover the metal socket 7 after plugging.

[0063] Mechanical sealing is performed between the flanges by means of eight fastening nuts 12 , with the fastening torque maintained above 180 N. Finally, plug components are installed in the two mounting threaded holes 10 and 11 at the top of the second flange 2 .

[0064] Example 3

[0065] The metal conductor 3 is connected to the first flange 1 by sealing and insulating it through the sealing glass 4, and the steps are as follows:

[0066] 1) Assemble the first flange 1, the sealing glass 4, and the metal conductor 3 together through a graphite fixture;

[0067] 2) The assembled whole is placed in a nitrogen atmosphere sintering furnace at 910°C, and the high-temperature sintering time is controlled at 18 minutes;

[0068] 3) The sintered electrical penetration parts are surface treated to make the metal flange surface clean and bright, with no oxide layer remaining on the surface;

[0069] 4) Conductor gold plating is performed on the electrical penetration components with surface treatment.

[0070] The metal conductor 3 is connected to the second flange 2 by sealing and insulating through the sealing glass 4, and the steps are as follows:

[0071] 1) Assemble the second flange 2, the sealing glass 4, and the metal conductor 3 together through a graphite fixture;

[0072] 2) The assembled whole is placed in a nitrogen atmosphere sintering furnace at 910°C, and the high-temperature sintering time is controlled at 18 minutes;

[0073] 3) The sintered electrical penetration parts are surface treated to make the metal flange surface clean and bright, with no oxide layer remaining on the surface;

[0074] 4) Conductor gold plating is performed on the electrical penetration components with surface treatment.

[0075] The surfaces of all the sealing glasses 4 are filled with elastic sealant 6. The elastic sealant 6 in this embodiment is made of silicone rubber, and a polyetheretherketone insulating sleeve 5 is placed and cured together with the silicone rubber to form a whole.

[0076] After curing, the metal conductors 3 of the first flange 1 and the second flange 2 are connected by trial plugging through the metal socket 7 to ensure that the pull-out force is above 38 N. At the same time, a metal sealing gasket 9 is placed in the installation groove of the second flange 2. The metal sealing gasket 9 used in this embodiment is a metal C ring. A polytetrafluoroethylene insulating sleeve 8 is placed outside the metal socket 7 to ensure that the polytetrafluoroethylene insulating sleeve 8 can completely cover the metal socket 7 after plugging.

[0077] Mechanical sealing is performed between the flanges through 10 fastening nuts 12, and the fastening torque is maintained above 175N. Finally, a plug component is installed in the mounting threaded hole 10 at the top of the second flange 2, and a pressure gauge is installed in the mounting threaded hole 11.

[0078] The prepared low-pressure instrument electrical penetration parts for LNG were tested for gas leakage rate, insulation resistance, conduction resistance, withstand voltage value, and withstand voltage value after immersion in low-temperature liquid nitrogen for 30 minutes. Among them, the gas leakage rate was measured by a helium mass spectrometer leak detector, the insulation resistance was measured by an insulation resistance tester, the conduction resistance was measured by a resistance tester, the withstand voltage value was measured by a withstand voltage tester, and the withstand voltage value was measured by a pressure test platform. The above performance test data are summarized in the following table:

[0079]

[0080] The above implementation modes are only used to illustrate the present invention, but not to limit the present invention. Ordinary technicians in the relevant technical field can make various changes and modifications without departing from the spirit and scope of the present invention. Therefore, all equivalent technical solutions also belong to the scope of the present invention. The patent protection scope of the present invention should be defined by the claims.

Claims

1. A glass-metal sealed low-pressure instrument electrical penetration for LNG, characterized in that: It includes a first flange, a second flange, a metal conductor, a metal socket, a sealing glass, a metal sealing gasket, a mounting threaded hole, and a fastening nut; the first flange and the second flange are provided with a plurality of sealing holes, and the sealing glass and the corresponding metal conductor are sintered in the sealing holes for sealing and insulation; the first flange and the second flange are mechanically sealed and connected through the fastening nut; a cavity is reserved inside the second flange, and the metal conductors encapsulated in the first flange and the second flange are electrically connected in the cavity through the metal socket; a mounting groove is provided on the end face of the second flange, and a metal sealing gasket is arranged in the mounting groove; and a mounting threaded hole is provided on the second flange.

2. According to claim 1, a glass-metal sealed low-pressure instrument electrical penetration for LNG, characterized in that: The sealing holes on the first flange and the second flange have the same type spectrum, and the specifications and depths of the sealing holes are consistent; sealing glass and metal conductors are placed in the sealing holes, and then the flanges and the metal conductors are formed into a whole through high-temperature sintering, thereby achieving a sealed and insulated connection.

3. A glass-to-metal sealed low-pressure instrument electrical penetration for LNG as claimed in claim 1, characterized in that: The specific steps of sealing and insulatingly connecting the first flange and the second flange with the corresponding metal conductor through the sealing glass are as follows: 1) Assemble the first flange or the second flange, the sealing glass, and the metal conductor together through a graphite fixture; 2) The assembled whole is placed in a nitrogen atmosphere sintering furnace at 870-930°C, and the high temperature sintering time is controlled at 15-25 minutes; 3) The sintered electrical penetration parts are surface treated to make the flange surface clean and bright, with no oxide layer remaining on the surface; 4) Conductor gold plating is performed on the electrical penetration components with surface treatment.

4. A glass-to-metal sealed low-pressure instrument electrical penetration for LNG as claimed in claim 1, characterized in that: In the first flange, both end surfaces of the sealing glass are filled with elastic sealant, and an insulating sleeve 1 is installed at both ends of the sealing glass. The insulating sleeve 1 is solidified into a whole through the elastic sealant; the material of the insulating sleeve 1 is polytetrafluoroethylene or polyetheretherketone.

5. The glass-to-metal sealed low-pressure instrument electrical penetration for LNG according to claim 1, characterized in that: In the second flange, the outer surfaces of both ends of the sealing glass are filled with elastic sealant, and an insulating sleeve 1 is installed at the outer end of the sealing glass. The insulating sleeve 1 is solidified into a whole through the elastic sealant; the material of the insulating sleeve 1 is polytetrafluoroethylene or polyetheretherketone.

6. A glass-to-metal sealed low-pressure instrument electrical penetration for LNG as claimed in claim 1, characterized in that: The metal socket is inserted into the metal conductor inside the second flange. The length of the metal socket is greater than the length of the metal conductor exposed outside the second flange. The metal socket forms an electrical connection with the metal conductor after the first flange and the second flange are mechanically sealed.

7. A glass-to-metal sealed low-pressure instrument electrical penetration for LNG as claimed in claim 1, characterized in that: The metal jack is covered with an insulating sleeve 2, the length of which is greater than that of the metal jack, and the insulating sleeve 2 simultaneously covers the insulating sleeve 1 on the inner surface of the first flange sealing glass; the insulating sleeve 2 is fixed by elastic sealant.

8. The glass-to-metal sealed low-pressure instrument electrical penetration for LNG according to claim 1, characterized in that: The metal socket has a double-ended wire spring structure inside, the metal socket is made of beryllium copper or tin bronze, the surface of the metal socket is silver-plated, the metal socket and the metal conductor are tightly fitted, and the pull-out force is between 30 and 60N.

9. A glass-to-metal sealed low-pressure instrument electrical penetration for LNG as claimed in claim 1, characterized in that: The first flange and the second flange are made of 304 stainless steel, and the metal conductor is made of Kovar alloy; the temperature is 20-300°C, and the expansion coefficient of the sealing glass is 90-100×10 -7 / K.

10. The glass-to-metal sealed low-pressure instrument electrical penetration for LNG according to claim 1, characterized in that: The installation groove is formed on the assembly surface of the second flange, and the opening position is 30 to 50 mm from the sealing hole farthest from the center of the circle; the metal sealing gasket is a metal O-ring or a metal C-ring; the installation threaded hole is used to install a plug component or a pressure gauge.

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