Double-sealing device suitable for ultralow-temperature regulating valve

Abstract

The invention relates to the technical field of valves, in particular to a double-sealing device suitable for an ultralow-temperature regulating valve, which comprises a valve body and a valve cover, a wound gasket is arranged between the valve body and the valve cover, a first sealing device and a second sealing device are arranged in the valve body, and the first sealing device is a corrugated pipe sealing assembly. A corrugated pipe sealing assembly located in the middle of a valve body is arranged, the structure is composed of a valve rod, a corrugated pipe body and a guide cover, the corrugated pipe body is made of a nickel base alloy material, and the two ends of the corrugated pipe body are welded to the valve rod and the guide cover correspondingly. In the working process, the valve rod axially moves to drive the corrugated pipe body to be stretched or compressed, due to the fact that the corrugated pipe body is located in the middle of the valve rod and is in static welding sealing, an ultralow-temperature medium leakage path can be preferentially blocked, and continuous relative movement of the valve rod and filler in traditional single filler sealing is avoided. Therefore, sealing performance reduction caused by abrasion is reduced from the source, the problem that the sealing performance is reduced along with the number of actions is solved, and a reliable first sealing defense line is formed.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of valves, in particular to a double sealing device suitable for ultra-low temperature control valve. BACKGROUND

[0002] In the field of storage, transportation and application of ultra-low temperature medium such as liquefied natural gas and liquid nitrogen, the ultra-low temperature control valve is the key equipment to ensure the safe and stable operation of the system. Such medium is usually in an extremely low temperature environment, and most of them have the characteristics of flammability and explosiveness, which puts high requirements on the sealing performance of the ultra-low temperature control valve. Once the sealing fails and the medium leaks, not only the medium will be lost, but also serious safety accidents may be caused.

[0003] Most of the existing ultra-low temperature control valves use single packing seal to solve the problem of leakage at the valve stem. However, this sealing method has obvious defects. During the opening and closing of the valve, there is a continuous relative movement between the valve stem and the packing. With the increase of the number of actions, the packing will be gradually worn out, and the sealing performance will be reduced. At the same time, the ultra-low temperature environment will cause uneven shrinkage of the material, which may cause the valve stem to bend and the surface roughness of the valve stem and packing to change, further aggravating the leakage, so that the packing seal is difficult to meet the strict requirements of fugitive emission under ultra-low temperature working conditions. Therefore, it is particularly necessary to develop a device that can maintain good sealing performance in an ultra-low temperature environment. Therefore, a double sealing device suitable for ultra-low temperature control valve is proposed. SUMMARY

[0004] 1. Technical problems solved The purpose of the present application is to provide a double sealing device suitable for ultra-low temperature control valve to solve the problems in the background art.

[0005] The double sealing device suitable for the ultra-low temperature regulating valve comprises a valve body and a valve cover, a winding gasket is arranged between the valve body and the valve cover, a first sealing device and a second sealing device are arranged in the valve body, the first sealing device is a bellows sealing assembly arranged at the middle position of the valve body, the bellows sealing assembly is composed of a valve rod and a bellows body sleeved on the outer periphery of the valve rod, the bellows body is made of a nickel-based alloy material, one end of the bellows body is welded with the valve rod, a guide cover is integrated with the winding gasket and is fixed on the valve body and the valve cover through flange bolts, the other end of the bellows body is welded with the guide cover sleeved on the outer periphery thereof, the guide cover is made of a ceramic matrix composite material, a cylindrical channel is formed between the guide cover and the bellows body, the inner wall and the outer wall of the cylindrical channel are provided with symmetrical wave-shaped protrusions extending in the axial direction, the valve rod moves in the axial direction to drive the bellows body to stretch or compress to realize the opening and closing action of the valve, the guide cover is fixed on the valve body and the valve cover through the flange bolts, a rotation prevention block for limiting is arranged on the guide cover, the rotation prevention block is made of a bakelite material and can prevent the valve rod from rotating to protect the bellows body, the second sealing device is a packing sealing device arranged at the right end of the bellows body assembly, the packing sealing device is composed of a packing seat provided with a packing body at the top, a packing gland arranged at the right end of the packing seat and a sealing plate provided with a dustproof ring arranged at the right end of the packing gland, symmetrical wave-shaped protrusions extending in the axial direction are arranged on the two sides of the packing gland, the packing body is made of a polyphenylene sulfide composite material or a polyimide composite material, the sealing plate is made of a titanium alloy material and is fixed at the right end of the guide cover through a nut and a stud, the nut and the stud are made of a precipitation hardening stainless steel material, the valve body and the valve cover are made of a low-temperature austenitic stainless steel material, the winding gasket is composed of a metal band and a polyphenylene sulfide composite added with wear-resistant particles, or is composed of a metal band and a polyimide composite added with reinforcing fibers; By adopting the technical scheme, the corrugated pipe sealing assembly is arranged at the middle position of the valve body, the structure is composed of a valve rod, a corrugated pipe body and a guide cover, the corrugated pipe body is made of a nickel-based alloy material, and the two ends are welded with the valve rod and the guide cover respectively. When working, the axial movement of the valve rod drives the corrugated pipe body to stretch or compress. Since it is at the middle position of the valve rod and is a static welded seal, it can preferentially block the leakage path of the ultra-low temperature medium, avoiding the continuous relative movement of the valve rod and the packing in the traditional single packing seal. Thus, the sealing performance decline caused by wear is reduced from the root, the problem of sealing performance decline with the number of actions is solved, and a reliable first line of defense is formed. The packing sealing device is arranged at the right end of the corrugated pipe body assembly, which is composed of a packing body, a packing seat, a packing gland and a sealing plate. The packing body is made of a polyphenylene sulfide composite material or a polyimide composite material. The packing gland has symmetrical wave-shaped protrusions on both sides. When the first sealing device fails, the device acts as the main seal, and the packing body is pressed tightly against the valve rod by the packing gland and the sealing plate. In this process, the characteristics of the material and the structural design ensure the sealing performance under ultra-low temperature, forming a "first protection + second emergency main seal" mode, which is more reliable than the conventional double seal and improves the sealing redundancy. The cylindrical channel formed by the guide cover and the corrugated pipe body and the symmetrical wave-shaped protrusions, as well as the anti-rotation block on the guide cover. When working, the cylindrical channel and the protrusions extend the heat conduction path, enhance the heat insulation effect, and reduce the uneven shrinkage of the valve body and the valve cover caused by temperature gradient; the anti-rotation block limits the rotation of the valve rod to avoid damage to the corrugated pipe body due to twisting. Thus, the long-term stability of the first sealing device is ensured, and the problems of valve rod bending, surface roughness change and other problems caused by material shrinkage are solved; the guide cover and the winding pad are integrated, and are fixed on the valve body and the valve cover through flange bolts. When installing, the structure makes the corrugated pipe sealing assembly accurately positioned, reducing the assembly deviation. In operation, this fixing method cooperates with the middle position of the corrugated pipe body to improve the overall structural stability, making it more suitable for ultra-low temperature harsh conditions and meeting the strict requirements of fugitive emissions.

[0006] Preferably, the cross section of the symmetrical wave-shaped protrusion is arc-shaped, and the spacing between adjacent protrusions is uniform, to ensure uniform extension of the heat conduction path; By adopting the technical scheme, the cross section of the symmetrical wave-shaped protrusion is arc-shaped and the spacing is uniform, which can uniformly extend the heat conduction path and ensure the uniformity of the heat insulation effect, further reducing the shrinkage difference of the valve body and the valve cover caused by uneven temperature, and improving the structural stability of the device in an ultra-low temperature environment.

[0007] Preferably, the nickel-based alloy material contains chromium, molybdenum and iron elements; By adopting the technical scheme, the nickel-based alloy material contains chromium, molybdenum and iron elements, the chromium improves corrosion resistance and oxidation resistance, the molybdenum enhances corrosion resistance and strength in reducing medium, and the iron optimizes comprehensive performance, so that the bellows body is more durable under ultra-low temperature and complex working conditions, and the reliability of the sealing assembly is ensured.

[0008] Preferably, the ceramic matrix composite material is a silicon carbide ceramic matrix composite material. By adopting the technical scheme, the polyphenylene sulfide composite material is added with glass fiber reinforced bodies of short fibers, and the polyimide composite material is added with carbon fiber reinforced bodies of continuous fibers.

[0009] Preferably, the glass fiber reinforced bodies added in the polyphenylene sulfide composite material are short fibers, and the material has good ultra-low temperature resistance; the carbon fiber reinforced bodies added in the polyimide composite material are continuous fibers, and the material can maintain high tensile strength in an ultra-low temperature environment, so as to ensure excellent sealing performance and service life. By adopting the technical scheme, the polyphenylene sulfide composite material is added with glass fiber reinforced bodies of short fibers, and the polyimide composite material is added with carbon fiber reinforced bodies of continuous fibers, so that the filler body can maintain good performance under ultra-low temperature, ensure sealing performance and service life, and effectively play the role of the emergency main sealing of the second sealing device.

[0010] Preferably, the low-temperature austenitic stainless steel material contains sufficient nickel elements to ensure good toughness and anti-brittle fracture capability in an ultra-low temperature environment. By adopting the technical scheme, the low-temperature austenitic stainless steel material contains sufficient nickel elements, which can ensure the toughness and anti-brittle fracture capability of the material in an ultra-low temperature environment, avoid damage of the valve body and the valve cover due to low-temperature embrittlement, and ensure the stability of the overall structure of the device.

[0011] Preferably, the titanium alloy material is a titanium alloy suitable for ultra-low temperature working conditions and having excellent low-temperature mechanical properties. By adopting the technical scheme, the titanium alloy material is suitable for ultra-low temperature working conditions and has excellent low-temperature mechanical properties, so that the sealing pressure plate can stably press the filler body under ultra-low temperature, ensure the sealing effect of the filler sealing device, and meet the strength requirements of the ultra-low temperature environment.

[0012] Preferably, the precipitation hardening stainless steel material is a precipitation hardening stainless steel that can obtain high strength through aging treatment and has good corrosion resistance in an ultra-low temperature environment. By adopting the technical scheme, the precipitation hardening stainless steel material can obtain high strength through aging treatment and has good corrosion resistance in an ultra-low temperature environment, so that the nut and the stud can stably fix the sealing pressure plate, avoid loosening of the connection due to low temperature or corrosion, and ensure reliable operation of the filler sealing device.

[0013] 2. Beneficial effects In summary, the present application includes at least one of the following beneficial technical effects: 1. The present application provides a double sealing device suitable for ultra-low temperature control valve, by setting the bellows sealing assembly in the middle position of the valve body, the structure is composed of valve stem, bellows body and guide cover, the bellows body is made of nickel-based alloy material, and the two ends are welded with valve stem and guide cover respectively. When working, the axial movement of the valve stem drives the bellows body to stretch or compress. Since it is in the middle position of the valve stem and is a static welded seal, it can preferentially block the leakage path of ultra-low temperature medium, avoiding the continuous relative movement of the valve stem and the packing in the traditional single packing seal. Thus, the sealing performance decline caused by wear is reduced from the root, solving the problem of sealing performance decline with the number of actions, forming a reliable first line of defense; By setting the packing sealing device at the right end of the bellows body assembly, which is composed of packing body, packing seat, packing gland and sealing plate, the packing body is made of polyphenylene sulfide composite material or polyimide composite material, and the packing gland has symmetrical wave-shaped protrusions on both sides. When the first sealing device fails, the device acts as the main seal, and the packing body is pressed tightly against the valve stem by the packing gland and the sealing plate. In this process, the material properties and structural design ensure the sealing performance at ultra-low temperature, forming a "first protection + second emergency main seal" mode, which is more reliable than the conventional double seal and improves the sealing redundancy.

[0014] 2. The present application provides a double sealing device suitable for ultra-low temperature control valve, by setting the guide cover and the bellows body to form a cylindrical channel and symmetrical wave-shaped protrusions, and anti-rotation blocks on the guide cover. When working, the cylindrical channel and the protrusions extend the heat conduction path, enhance the heat insulation effect, and reduce the uneven shrinkage of the valve body and the valve cover caused by temperature gradient; the anti-rotation blocks limit the rotation of the valve stem to avoid damage to the bellows body due to twisting. Thus, the long-term stability of the first sealing device is ensured, solving the problem of intensified leakage caused by valve stem bending and surface roughness change; By setting the guide cover and the winding pad into an integrated structure, and fixing it on the valve body and the valve cover through flange bolts. When installing, this structure allows the bellows sealing assembly to be positioned accurately, reducing assembly deviation. In operation, this fixing method cooperates with the middle position of the bellows body to improve the overall structural stability, making it more suitable for ultra-low temperature harsh conditions and meeting the strict requirements of fugitive emissions. BRIEF DESCRIPTION OF DRAWINGS

[0015] Figure 1 The structure of the present application is shown in the figure; Figure 2 The structure of the first sealing device of the present application is shown in the enlarged view; Figure 3 The structure of the bellows body and the guide cover of the present application is shown in the local cross-sectional view; Figure 4Structure diagram of the valve body-seal assembly material of the present application; Figure 1 Structure diagram of the valve body-seal assembly material of the present application; Figure 5 Structure diagram of the valve body-seal assembly material of the present application; Figure 6 Structure diagram of the valve body-seal assembly material of the present application; Figure 7 Structure diagram of the valve body-seal assembly material of the present application.

[0016] 1, valve body; 2, valve cover; 201, low-temperature austenitic stainless steel material; 3, winding gasket; 4, first sealing device; 401, valve rod; 402, bellows body; 4002, nickel-based alloy material; 403, guide cover; 4003, ceramic matrix composite material; 404, cylindrical channel; 405, symmetrical wavy protrusion; 406, anti-rotation block; 4006, bakelite material; 5, second sealing device; 501, packing body; 5001, polyphenylene sulfide composite material; 502, packing seat; 503, packing gland; 504, sealing plate; 5004, titanium alloy material; 6, nut; 7, stud; 701, precipitation hardening stainless steel material. DETAILED DESCRIPTION

[0017] The following will be described in detail with reference to the accompanying drawings. Figure 1 - The accompanying drawings illustrate the present application by way of example, and not limitation. Figure 7 The present application will be described in further detail below.

[0018] Example 1: A double sealing device suitable for ultra-low temperature regulating valve, referring to Figure 1 , Figure 2 and Figure 3The utility model relates to a valve, including valve body 1 and valve cover 2, be equipped with winding pad 3 between valve body 1 and valve cover 2, be equipped with first sealing device 4 and second sealing device 5 in valve body 1, first sealing device 4 is bellows seal assembly, set up in the intermediate position of valve body 1, this bellows seal assembly is by valve stem 401 and the bellows body 402 of setting in the outer periphery of valve stem 401 are composed, the bellows body 402 adopts nickel base alloy material 4002 and is made, one end of bellows body 402 is welded with valve stem 401 and connects, guide cover 403 with winding pad 3 constitutes integrated structure and is fixed on valve body 1 and valve cover 2 through flange bolt, the other end of bellows body 402 is welded with the guide cover 403 of setting in its outer periphery, guide cover 403 adopts ceramic matrix composite material 4003 and is made, and guide cover 403 and bellows body 402 between form cylindrical passage 404, the inner wall and outer wall of cylindrical passage 404 are equipped with the symmetrical wave shape protruding 405 of extending along the axial direction, valve stem 401 along the axial movement can drive bellows body 402 to stretch or compress to realize the switch action of valve, guide cover 403 is fixed on valve body 1 and valve cover 2 through flange bolt, and guide cover 403 is equipped with the anti-rotation block 406 of limiting, anti-rotation block 406 adopts bakelite material 4006 and is made, can prevent valve stem 401 rotation to protect bellows body 402, second sealing device 5 is packing seal device, sets up in the right end of bellows body 402 component, and packing seal device is by the packing seat 502 of being equipped with the packing body 501 in top, the packing gland 503 of setting up in the right end of packing seat 502 and the sealing pressure plate 504 of setting up in the right end of packing gland 503 with dustproof ring, the both sides of packing gland 503 are equipped with the symmetrical wave shape protruding 405 of extending along the axial direction, and packing body 501 adopts polyphenylene sulfide composite material 5001 or polyimide composite and is made, and sealing pressure plate 504 adopts titanium alloy material 5004 and is made, is fixed in the right end of guide cover 403 through nut 6 and stud 7, and nut 6 and stud 7 adopt precipitation hardening stainless steel material 701 and are made, valve body 1 and valve cover 2 adopt low temperature austenitic stainless steel material 201 and are made, winding pad 3 adopts metal band and adds and is compounded with polyphenylene sulfide and has wear-resistant particle, or adopts metal band and adds and is compounded with polyimide and has reinforcing fiber, by setting up in the intermediate position of valve body 1 bellows seal assembly, this structure is by valve stem 401, bellows body 402 and guide cover 403, and bellows body 402 adopts nickel base alloy material 4002, and both ends are welded with valve stem 401, guide cover 403 respectively.Working, valve stem 401 axial movement drives bellows body 402 to stretch or compress, because being in the intermediate position of valve stem 401 and being static welded seal, can preferentially block the outside leakage path of ultralow temperature medium, avoids the continuous relative motion of valve stem 401 and packing in traditional single packing seal.Thus, the root cause of wear-induced sealing performance degradation is reduced, the problem of sealing performance degradation with the number of actions is solved, and a reliable first sealing defense line is formed; by setting the packing seal device located at the right end of the bellows body 402 assembly, the packing body 501, the packing seat 502, the packing gland 503 and the sealing plate 504 are composed, the packing body 501 adopts polyphenylene sulfide composite material 5001 or polyimide composite material, the packing gland 503 has symmetrical wave-shaped protrusions 405 on both sides. When the first sealing device 4 fails, the device acts as a main seal, and the packing body 501 is pressed tightly against the valve stem 401 by the packing gland 503 and the sealing plate 504. In this process, the material properties and structural design ensure the sealing performance at ultra-low temperature, forming a "first protection + second emergency main sealing" mode, which is more reliable than the conventional double sealing and improves the sealing redundancy; by setting the cylindrical channel 404 formed by the guide cover 403 and the bellows body 402 and the symmetrical wave-shaped protrusions 405, and the anti-rotation block 406 on the guide cover 403. When working, the cylindrical channel 404 and the protrusions extend the heat conduction path, enhance the heat insulation effect, and reduce the uneven shrinkage of the valve body 1 and the valve cover 2 caused by temperature gradient; the anti-rotation block 406 limits the rotation of the valve stem 401 to avoid damage to the bellows body 402 due to torsion. Thus, the long-term stability of the first sealing device 4 is ensured, and the problems of valve stem 401 bending, surface roughness change and other problems caused by material shrinkage are solved; by setting the guide cover 403 and the winding gasket 3 in an integrated structure, and fixed on the valve body 1 and the valve cover 2 by flange bolts. When installing, this structure makes the bellows sealing assembly accurately positioned, reducing assembly deviation. In work, this fixing method cooperates with the middle position of the bellows body 402 to improve the overall structural stability, making it more suitable for ultra-low temperature harsh working conditions and meeting the strict requirements of fugitive emissions.

[0019] Referring to Figure 1 , Figure 5 and Figure 6 , the cross section of the symmetrical wave-shaped protrusion 405 is arc-shaped, and the spacing between adjacent protrusions is uniform to ensure uniform extension of the heat conduction path, the nickel-based alloy material 4002 contains chromium, molybdenum and iron elements, the cross section of the symmetrical wave-shaped protrusion 405 is arc-shaped and the spacing is uniform, which can uniformly extend the heat conduction path and ensure the uniformity of the heat insulation effect, further reducing the shrinkage difference of the valve body 1 and the valve cover 2 caused by uneven temperature, improving the structural stability of the device in ultra-low temperature environment, the nickel-based alloy material 4002 contains chromium, molybdenum and iron elements, chromium improves corrosion resistance and oxidation resistance, molybdenum enhances corrosion resistance and strength in reducing media, and iron optimizes comprehensive performance, making the bellows body 402 more durable in ultra-low temperature and complex working conditions, and ensuring the reliability of the sealing assembly.

[0020] Referring to Figure 1 , Figure 5 and Figure 7, the ceramic matrix composite material 4003 is a silicon carbide ceramic matrix composite material 4003, the glass fiber reinforced body with short fibers is added in the polyphenylene sulfide composite material 5001, the carbon fiber reinforced body with continuous fibers is added in the polyimide composite material, the ceramic matrix composite material 4003 is a silicon carbide ceramic matrix composite material 4003, the silicon carbide ceramic matrix composite material 4003 has the characteristics of high strength, high temperature resistance and oxidation resistance, improves the structural stability and thermal insulation performance of the guide cover 403 in the ultra-low temperature environment, better protects the bellows body 402 and maintains the thermal insulation effect of the cylindrical channel 404, the polyphenylene sulfide composite material 5001 adds the short glass fiber reinforced body, and the polyimide composite material adds the continuous carbon fiber reinforced body, so that the filler body 501 maintains good performance in the ultra-low temperature, ensures the sealing performance and service life, and can effectively play the emergency main sealing role of the second sealing device 5.

[0021] With reference to Figure 1 , Figure 2 and Figure 7 , the low-temperature austenitic stainless steel material 201 contains sufficient nickel elements to ensure good toughness and brittle fracture resistance in the ultra-low temperature environment, the titanium alloy material 5004 is a titanium alloy suitable for ultra-low temperature working conditions and has excellent low-temperature mechanical properties, the precipitation hardening stainless steel material 701 is a precipitation hardening stainless steel that can obtain high strength through aging treatment and has good corrosion resistance in the ultra-low temperature environment, the low-temperature austenitic stainless steel material 201 contains sufficient nickel elements to ensure the toughness and brittle fracture resistance of the material in the ultra-low temperature environment, to avoid damage to the valve body 1 and the valve cover 2 due to low-temperature embrittlement, and to ensure the stability of the overall structure of the device, the titanium alloy material 5004 is suitable for ultra-low temperature working conditions and has excellent low-temperature mechanical properties, so that the sealing pressure plate 504 can be tightly pressed against the filler body 501 in the ultra-low temperature, ensuring the sealing effect of the filler sealing device, adapting to the strength requirements of the ultra-low temperature environment, the precipitation hardening stainless steel material 701 can obtain high strength through aging treatment and has good corrosion resistance in the ultra-low temperature, so that the nut 6 and the stud 7 can stably fix the sealing pressure plate 504, avoiding loosening of the connection due to low temperature or corrosion, and ensuring reliable operation of the filler sealing device.

[0022] The implementation principle of the embodiment of the application is as follows: the double sealing device mainly comprises a valve body 1, a valve cover 2, a winding gasket 3, a first sealing device 4 and a second sealing device 5. The valve body 1 is connected with the valve cover 2 through flange bolts, and the winding gasket 3 between the valve body 1 and the valve cover 2 plays a sealing role. The first sealing device 4 is a bellows sealing assembly and is arranged at the middle position of the valve body 1. When the valve rod 401 moves in the axial direction, the bellows body 402 sleeved on the outer periphery of the valve rod 401 is stretched or compressed, so that the opening and closing action of the valve is realized. One end of the bellows body 402 is welded with the valve rod 401, and the other end is welded with the guide cover 403 sleeved on the outer periphery of the bellows body 402, so as to form a static seal and block the external leakage path of the ultra-low temperature medium in priority. The guide cover 403 and the winding gasket 3 form an integrated structure and are fixed on the valve body 1 and the valve cover 2 through flange bolts, so as to provide stable support for the bellows body 402. The guide cover 403 and the related components have the following effects: the guide cover 403 is made of ceramic matrix composite material 4003, and a cylindrical channel 404 is formed between the guide cover 403 and the bellows body 402. The symmetrical wave-shaped protrusions 405 on the inner wall and the outer wall of the channel can prolong the heat conduction path and enhance the heat insulation effect. The anti-rotation block 406 on the guide cover 403 is made of bakelite material 4006, which can limit the rotation of the valve rod 401 and avoid damage to the bellows body 402 due to torsion. The working process of the second sealing device 5: the second sealing device 5 is a packing sealing device and is arranged at the right end of the bellows body 402 assembly. The packing body 501 is arranged in the packing seat 502 and is compressed by the packing gland 503 and the sealing pressing plate 504, so as to form a sealing structure closely attached to the valve rod 401. The sealing pressing plate 504 is fixed at the right end of the guide cover 403 through the nut 6 and the stud 7, so as to ensure that the packing body 501 always maintains effective sealing pressure. When the first sealing device 4 fails, the second sealing device 5 can play a role as the main sealing to prevent the medium from leaking outside. The cooperation of various materials: the valve body 1 and the valve cover 2 are made of low-temperature austenitic stainless steel material 201, which can adapt to the ultra-low temperature environment; the bellows body 402 is made of nickel-based alloy material 4002, which ensures the reliability of the welded seal; the packing body 501 is made of polyphenylene sulfide composite material 5001 or polyimide composite material, which can maintain good sealing performance at ultra-low temperature; the nut 6 and the stud 7 are made of precipitation hardening stainless steel material 701, which ensures the stability of the connection; during the operation of the valve, the first sealing device 4 serves as the main sealing line, and the welded seal of the bellows body 402 blocks the leakage of the medium; the second sealing device 5 serves as the standby sealing line and plays a main sealing role when the first sealing device 4 fails. At the same time, the heat insulation design of the guide cover 403, the anti-rotation protection of the anti-rotation block 406 and the adaptability of the materials of various components jointly ensure the stable operation of the device under the ultra-low temperature working condition and meet the sealing requirements.

[0023] The embodiments of the present application are preferred embodiments of the present application, and are not intended to limit the protection scope of the present application, wherein the same parts are denoted by the same reference numerals. Therefore, any equivalent changes made according to the structure, shape and principle of the present application should be covered within the protection scope of the present application.

Claims

1. A double sealing device suitable for a cryogenic regulating valve, comprising a valve body (1) and a valve cover (2), a wound gasket (3) being provided between the valve body (1) and the valve cover (2), and a first sealing device (4) and a second sealing device (5) being provided within the valve body (1), characterized in that: The first sealing device (4) is a bellows body (402) sealing assembly, which is arranged in the middle position of the valve body (1). The bellows body (402) sealing assembly consists of a valve stem (401) and a bellows body (402) sleeved on the outer periphery of the valve stem (401). The bellows body (402) is made of nickel-based alloy material (4002). One end of the bellows body (402) is welded to the valve stem (401). The guide cover (403) and the spiral wound gasket (3) form an integrated structure and are fixed to the valve body (1) and the valve cover (2) by flange bolts. The other end of the bellows body (402) is sleeved on the valve stem (401). The guide cover (403) on the outer periphery is welded and made of a ceramic-based composite material (4003). A cylindrical channel (404) is formed between the guide cover (403) and the bellows body (402). The inner and outer walls of the cylindrical channel (404) are provided with symmetrical wave-shaped protrusions (405) extending in the axial direction. The valve stem (401) moves in the axial direction to drive the bellows body (402) to stretch or compress to realize the opening and closing action of the valve. The guide cover (403) is fixed to the valve body (1) and the valve cover (2) by flange bolts. An anti-rotation block (405) for limiting is provided on the guide cover (403). 06), the anti-rotation block (406) is made of bakelite material (4006), which can prevent the valve stem (401) from rotating to protect the bellows body (402), the second sealing device (5) is a packing sealing device, which is arranged at the right end of the bellows body (402) assembly, and the packing sealing device is composed of a packing seat (502) with a packing body (501) on the top, a packing gland (503) arranged at the right end of the packing seat (502), and a sealing pressure plate (504) with a dust ring arranged at the right end of the packing gland (503), and the packing gland (503) is provided with symmetrical wave-shaped protrusions (405) extending in the axial direction on both sides. ), the packing body (501) is made of a polyphenylene sulfide composite material (5001) or a polyimide composite material; the sealing pressure plate (504) is made of a titanium alloy material (5004) and is fixed to the right end of the guide cover (403) by a nut (6) and a stud (7), and the nut (6) and the stud (7) are made of a precipitation hardened stainless steel material (701); the valve body (1) and the valve cover (2) are made of a low-temperature austenitic stainless steel material (201), and the spiral wound gasket (3) is made of a metal strip and polyphenylene sulfide with wear-resistant particles added thereto, or a metal strip and polyimide with reinforcing fibers added thereto.

2. The double sealing device for a cryogenic regulating valve according to claim 1, characterized in that: The cross-section of the symmetrical wavy protrusions (405) is arc-shaped, and the spacing between adjacent protrusions is consistent, so as to ensure a uniform extension effect on the heat conduction path.

3. The double sealing device for a cryogenic regulating valve according to claim 1, characterized in that: The nickel-based alloy material (4002) contains chromium, molybdenum and iron elements.

4. The double sealing device for a cryogenic regulating valve according to claim 1, characterized in that: The ceramic-based composite material (4003) is a silicon carbide ceramic-based composite material (4003).

5. The double sealing device for a cryogenic regulating valve according to claim 1, characterized in that: The polyphenylene sulfide composite material (5001) is added with a glass fiber reinforcement of short fibers, and the polyimide composite material is added with a carbon fiber reinforcement of continuous fibers.

6. The double sealing device for a cryogenic regulating valve according to claim 1, characterized in that: The low-temperature austenitic stainless steel material (201) contains sufficient nickel elements to ensure good toughness and brittle fracture resistance in ultra-low temperature environments.

7. The double sealing device for a cryogenic regulating valve according to claim 1, characterized in that: The titanium alloy material (5004) is a titanium alloy suitable for ultra-low temperature working conditions and has excellent low-temperature mechanical properties.

8. The double sealing device for a cryogenic regulating valve according to claim 1, characterized in that: The precipitation hardening stainless steel material (701) is a precipitation hardening stainless steel that can obtain high strength through aging treatment and has good corrosion resistance in ultra-low temperature environments.

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