An online repairable ultra-low temperature butterfly valve

Abstract

The utility model relates to a kind of on-line maintenance ultra-low temperature butterfly valve, including valve body, butterfly plate, valve cover, valve stem, valve seat, support, transmission mechanism, and the valve seat installation cavity is equipped in valve body outlet passage inner wall;Valve seat positioning device and valve seat radial floating device are equipped between valve seat outer circular face and valve seat installation cavity inner wall, when installing valve seat, the position of valve seat conical sealing surface circumferential direction relative to valve stem center line can be positioned, ensure that valve seat conical sealing surface and butterfly plate conical sealing surface accurately cooperate, improve the coincidence degree of the center line of both conical sealing surface under cooperation state;In the process that butterfly plate and valve seat are pressed tightly, butterfly plate pushes valve seat to compress C type elastic ring to move to one side of larger pressure, automatically adjust the machining and installation error between valve seat and butterfly plate, improve the cooperation precision between butterfly plate conical surface sealing surface and valve seat conical sealing surface, and its on-line maintenance operation is convenient, and the sealing performance of product after maintenance is reliable.

Description

Technical Field

[0001] This utility model relates to a butterfly valve, and more particularly to a cryogenic butterfly valve that can be maintained online. This utility model is applicable to control valves for liquefied natural gas transmission pipelines. Background Technology

[0002] Liquefied natural gas (LNG) is characterized by ultra-low temperatures, flammability, and explosiveness. In pipelines, butterfly valves are mostly connected to the pipeline via welding at both ends, requiring the valves to have an online maintenance structure. Therefore, top-entry butterfly valves are generally used. However, due to the small size of LNG molecules, leaks are easily caused by inaccurate sealing surface precision or excessive torque in the butterfly valve. Because the sealing ring and seat of the butterfly valve have a conical structure, the sealing ring and seat must be aligned at different positions for accurate sealing. Although traditional top-entry butterfly valves allow for the removal of the valve cover to replace the butterfly plate and seat, the narrow valve cavity space between the butterfly plate and seat makes it impossible to accurately install the sealing ring and seat during maintenance, resulting in leakage at the sealing pair. This makes it difficult to achieve the required sealing performance after online replacement of the butterfly plate and seat. Utility Model Content

[0003] This invention addresses the problems existing in the prior art by providing a method for online maintenance of cryogenic butterfly valves. This method allows the conical sealing surface of the butterfly plate to automatically align with the conical sealing surface of the valve seat during online maintenance, ensuring the sealing performance of both surfaces and providing reliable sealing.

[0004] The technical solution for realizing this utility model is as follows: An online-maintainable cryogenic butterfly valve includes a valve body, a butterfly plate, a valve cover, a valve stem, a valve seat, a bracket, and a transmission mechanism. The valve body has an inlet channel and an outlet channel. The valve cover is installed in the middle cavity of the valve body to form an upper-mounted structure. The valve stem consists of an upper valve stem and a lower valve stem. The lower end of the upper valve stem is fixedly connected to a lug on the butterfly plate, and the upper end passes through the valve cover shaft hole and the bracket to connect with the transmission mechanism. The valve body outlet channel has a cylindrical pipe extending to the right side of the valve cover shaft hole. A valve seat mounting cavity is provided on the inner wall of the left end of the cylindrical pipe. The butterfly plate and the valve seat have mutually mating conical sealing surfaces. The bracket adopts an extended structure, and a packing seal device is provided between its upper end and the valve stem. The valve seat mounting cavity is characterized by being composed of a valve seat placement cavity and a fixing ring placement cavity. A sealing ring is provided between the valve seat mounting cavity and the right end face of the valve seat. A valve seat positioning device and a valve seat radial floating device are provided between the outer circular surface of the valve seat and the inner wall of the valve seat mounting cavity. The valve seat positioning device is composed of a radial positioning block on the outer circular surface of the valve seat and a positioning groove in the second step of the valve seat mounting cavity. The valve seat radial floating device is composed of a C-shaped elastic ring between the outer circular surface of the valve seat and the inner wall of the valve seat mounting cavity. The C-shaped elastic ring is installed in the annular groove on the outer circular surface of the valve seat, with its opening facing the valve body channel axis. The outer annular surface is pressed against the inner wall of the valve seat mounting cavity, and there is a clearance fit between the outer circular surface of the valve seat and the inner wall of the valve seat mounting cavity. When the valve seat is subjected to radial force, the C-shaped elastic ring can be compressed and deformed, causing the valve seat to float radially.

[0005] The preferred embodiment is that the butterfly plate conical sealing surface and the valve seat conical sealing surface are composed of an inclined surface located at the valve stem installation position and elliptical conical surfaces that gradually extend on both sides of the inclined surface.

[0006] The preferred solution is to install an elastic rubber O-ring inside the C-shaped elastic ring.

[0007] A preferred embodiment is to provide a composite sealing structure consisting of an energy storage sealing ring and a rubber sealing gasket between the valve cover and the valve body. The energy storage sealing ring is composed of an O-ring with an inner cavity of a U-shaped rubber lip sealing ring, and the opening of the U-shaped rubber lip sealing ring faces the inner ring surface.

[0008] The preferred embodiment is that the packing sealing device adopts a combined sealing structure, consisting of a second energy storage sealing ring, an integrated bearing packing pad, packing, and a packing gland. The second energy storage sealing ring consists of a U-shaped sealing ring and a rubber O-ring. The U-shaped sealing ring is installed between the outer surface of the upper valve stem and the bottom surface of the stuffing box of the bracket, with its U-shaped opening facing downwards. The rubber O-ring is embedded in the inner cavity of the U-shaped sealing ring. The integrated bearing packing pad and packing are sequentially pressed onto the U-shaped sealing ring by the packing gland, which is installed on the upper end face of the bracket by bolts and a butterfly spring.

[0009] A preferred embodiment is to provide a drainage groove on the upper end face of the support, wherein the drainage groove is composed of several radial inclined grooves arranged in the circumferential direction on the upper end face of the support.

[0010] The advantages of this invention compared to existing technologies are that a valve seat positioning device and a valve seat radial floating device are provided between the outer circular surface of the valve seat and the inner wall of the valve seat mounting cavity. When installing the valve seat, the position of the valve seat conical sealing surface circumferentially relative to the valve stem centerline can be positioned to ensure accurate matching between the valve seat conical sealing surface and the butterfly plate conical sealing surface, improving the overlap of the centerlines of the conical sealing surfaces of the two in the matching state. During the pressing and fitting process between the butterfly plate and the valve seat, the butterfly plate pushes the valve seat compression C-shaped elastic ring to move towards the side with greater pressure, automatically adjusting the machining and installation errors between the valve seat and the butterfly plate, improving the fitting accuracy between the butterfly plate conical surface and the valve seat conical sealing surface. Its online maintenance operation is convenient and the sealing performance of the product after maintenance is reliable. Attached Figure Description

[0011] Figure 1 This is a structural cross-sectional view of the present invention.

[0012] Figure 2 This is a utility model Figure 1 Enlarged view of the local structure at point A in the middle.

[0013] Figure 3 This is a utility model Figure 1 Enlarged view of the local structure at point B in the middle.

[0014] Figure 4 This is a utility model Figure 1 Enlarged view of the local structure at point C.

[0015] Figure 5 This is a utility model Figure 1 A schematic diagram of the elliptical conical sealing surface of the valve seat.

[0016] In the diagram: 1. Bottom cover, 2. Four-ring, 3. Valve body, 4. Lower valve stem, 5. Butterfly plate, 6. Positioning ring, 7. Valve seat, 8. C-type elastic ring, 9. Sealing ring, 10. Energy storage sealing ring, 11. Valve cover, 12. Bracket, 13. Upper valve stem, 14. Drip tray, 15. Second energy storage sealing ring, 16. Integrated bearing packing pad, 17. Packing, 18. Packing gland, 19. Butterfly spring, 20. Transmission mechanism, 21. Upper inclined surface, 22. Lower inclined surface, 23. Left elliptical cone surface, 24. Right elliptical cone surface, 25. Drain groove, 26. Cylindrical pipe, 27. Outlet channel, 28. Elastic rubber O-ring, 29. Rubber sealing gasket. Detailed Implementation

[0017] like Figure 1The online-maintainable cryogenic butterfly valve shown includes a valve body 3, a butterfly plate 5, a valve cover 11, a valve stem, a valve seat 7, a bracket 12, and a transmission mechanism 20. The valve body 3 has an inlet channel and an outlet channel 27. The valve cover 11 is installed in the middle cavity of the valve body 3 to form an upper-mounted structure. The valve stem consists of an upper valve stem 13 and a lower valve stem 4. The lower end of the upper valve stem 13 is fixedly connected to the upper lug of the butterfly plate 5, and the upper end passes through the shaft hole of the valve cover 11 and the bracket 12 to connect with the transmission mechanism 20. The lower valve stem 4 is sealed in the shaft hole at the bottom of the valve body 3 by a bottom cover 1 and a four-ring 2. Its upper end is connected to the lower valve stem 4. The lower lug of the butterfly plate 5 is dynamically fitted. The outlet channel 27 of the valve body 3 has a cylindrical pipe 26 extending to the right side of the shaft hole of the valve cover 11. A valve seat mounting cavity is provided on the inner wall of the left end of the cylindrical pipe 26. The butterfly plate 5 and the valve seat 7 have mutually mating conical sealing surfaces. The valve stem, butterfly plate 5, and valve body 3 form a triple eccentric structure. The bracket 12 adopts an extended structure to reduce the transmission of the cryogenic medium to the transmission mechanism 20. A packing seal device is provided between the upper end of the bracket 12 and the valve stem. Its characteristic is that the valve seat mounting cavity consists of a valve seat placement cavity and a fixed cavity. The valve seat is assembled in a positioning ring cavity. A positioning ring 6 is installed inside the positioning ring cavity. The positioning ring 6 has a three-ring structure. The valve seat 7 is installed inside the valve seat cavity by bolts tightened around the circumference of the positioning ring 6. A sealing ring 9 is provided between the right radial step of the valve seat cavity and the right end face of the valve seat 7. A valve seat positioning device and a valve seat radial floating device are provided between the outer surface of the valve seat 7 and the inner wall of the valve seat cavity. The valve seat positioning device consists of a radial positioning block on the outer surface of the valve seat 7 and a positioning groove in the right step of the positioning ring cavity. When replacing the valve seat 7, only... To ensure proper alignment, the directional positioning block must be embedded into the positioning groove. This aligns the conical sealing surface of the valve seat 7 with the conical sealing surface of the butterfly plate 5, ensuring the proper fit of their sealing surfaces. The radial floating device for the valve seat consists of a C-shaped elastic ring 8 positioned between the outer surface of the valve seat 7 and the inner wall of the valve seat mounting cavity. The C-shaped elastic ring 8 is installed in the annular groove on the outer surface of the valve seat 7, with its opening facing the axis of the valve body 3 channel. Its outer annular surface is pressed against the inner wall of the valve seat mounting cavity, and there is a clearance fit between the outer surface of the valve seat 7 and the inner wall of the valve seat mounting cavity. Figure 2 As shown. During the closing process of the butterfly plate 5, when the circumferential force on the sealing surface of the butterfly plate 5 and the sealing surface of the valve seat 7 is uneven, the butterfly plate 5 will push the valve seat 7 to compress the C-shaped elastic ring 8 in the direction of greater force, deform and float, automatically adjusting the fitting accuracy between the sealing surface of the butterfly plate 5 and the sealing surface of the valve seat 7, improving the operability of online maintenance and component replacement, and the sealing performance of the product after maintenance.

[0018] The conical sealing surface of the butterfly plate 5 and the conical sealing surface of the valve seat 7 are composed of an inclined surface located at the valve stem installation position and elliptical conical surfaces that gradually extend on both sides of the inclined surface. The inclined surface is composed of a symmetrical upper inclined surface 21 and a lower inclined surface 22, and the elliptical conical surface is composed of a left elliptical conical surface 23 and a right elliptical conical surface 24. Figure 5As shown, the upper inclined surface 21 is located at the upper valve stem 13, the lower inclined surface 22 is located at the lower valve stem 4, and the left elliptical cone surface 23 and the right elliptical cone surface 24 are located symmetrically on both sides of the valve stem centerline, so that when the butterfly plate 5 and the valve seat 7 are fitted together, they form an elliptical cone sealing pair, thereby increasing the sealing pressure ratio.

[0019] An elastic rubber O-ring 28 is provided in the inner cavity of the C-type elastic ring 8. When the reverse medium compresses the elastic rubber O-ring 28, it deforms and radially expands the C-type elastic ring 8, thereby achieving a seal between the valve seat 7 and the valve body 3.

[0020] A composite sealing structure consisting of an energy storage sealing ring 10 and a rubber sealing gasket 29 is provided between the valve cover 11 and the valve body 3. The energy storage sealing ring 10 is composed of an O-ring installed in the inner cavity of a U-shaped rubber lip sealing ring. The opening of the U-shaped rubber lip sealing ring faces its inner ring surface. The medium enters from the opening of the U-shaped rubber lip sealing ring, compresses and deforms the O-ring, and opens the U-shaped rubber lip sealing ring to achieve a cavity seal between the valve cover 11 and the valve body 3. The rubber sealing gasket 29 is installed between the valve body 3 and the valve cover 11 outside the energy storage sealing ring 10 to further seal the trace amounts of medium leaking from the energy storage sealing ring 10, thus forming a double composite sealing structure in the cavity and improving the cavity sealing performance.

[0021] The packing seal device consists of a composite sealing structure composed of a second energy storage sealing ring 15, an integrated bearing packing pad 16, packing 17, and a packing gland 18. Figure 3 The second energy storage sealing ring 15 consists of a U-shaped sealing ring and a rubber O-ring. The U-shaped sealing ring is installed between the outer surface of the upper valve stem 13 and the bottom surface of the stuffing box of the bracket 12, with its U-shaped opening facing downwards. The rubber O-ring is embedded in the inner cavity of the U-shaped sealing ring. The integrated bearing packing pad 16 and packing 17 are sequentially pressed onto the U-shaped sealing ring by the packing gland 18. The medium enters through the opening of the U-shaped sealing ring, compressing the rubber O-ring and deforming it, thus radially expanding the U-shaped sealing ring and achieving the first seal between the bracket 12 and the upper valve stem 13. The packing 17 provides a second seal for the trace amounts of medium leaking from the second energy storage sealing ring 15, forming a composite sealing structure. The packing gland 18 is installed on the upper end face of the bracket 12 by bolts and a butterfly spring 19, using the elasticity of the butterfly spring 19 to automatically compensate for the wear of the packing 17.

[0022] A drainage groove 25 is provided on the upper end face of the bracket 12. The drainage groove 25 is composed of several radial inclined grooves arranged in the circumferential direction on the upper end face of the bracket 12.

[0023] To prevent liquefied water droplets from the cryogenic medium from flowing into the packing 17, such as... Figure 4 As shown, a drip tray 14 is installed on the bracket 12 below the drain trough 25 to prevent water droplets from falling onto the valve cover 11 and freezing.

Claims

1. An online-maintainable cryogenic butterfly valve, comprising a valve body (3), a butterfly plate (5), a valve cover (11), a valve stem, a valve seat (7), a bracket (12), and a transmission mechanism (20). The valve body (3) has an inlet channel and an outlet channel (27). The valve cover (11) is installed in the middle cavity of the valve body (3) to form an upper-mounted structure. The valve stem consists of an upper valve stem (13) and a lower valve stem (4). The lower end of the upper valve stem (13) is fixedly connected to the upper lug of the butterfly plate (5), and the upper end passes through the shaft hole of the valve cover (11). The bracket (12) is connected to the transmission mechanism (20). The outlet channel (27) of the valve body (3) has a cylindrical pipe (26) extending to the right side of the shaft hole of the valve cover (11). A valve seat mounting cavity is provided on the inner wall of the left end of the cylindrical pipe (26). There are mutually cooperating conical sealing surfaces between the butterfly plate (5) and the valve seat (7). The valve stem, butterfly plate (5), and valve body (3) form a triple eccentric structure. The bracket (12) adopts an extended structure, and a packing sealing device is provided between its upper end and the valve stem. Its characteristics are: The valve seat mounting cavity consists of two parts: a valve seat placement cavity and a fixing ring placement cavity. A positioning ring (6) is installed in the positioning ring placement cavity. The valve seat (7) is installed in the valve seat placement cavity by bolts tightened around the positioning ring (6). A sealing ring (9) is set between the right radial step of the valve seat placement cavity and the right end face of the valve seat (7). A valve seat positioning device and a valve seat radial floating device are provided between the outer circular surface of the valve seat (7) and the inner wall of the valve seat placement cavity. The valve seat positioning device is composed of a radial positioning block on the outer circular surface of the valve seat (7) and a positioning groove in the right step of the positioning ring placement cavity. The valve seat radial floating device is composed of a C-shaped elastic ring (8) set between the outer circular surface of the valve seat (7) and the inner wall of the valve seat placement cavity. The C-shaped elastic ring (8) is installed in the annular groove on the outer circular surface of the valve seat (7), with its opening facing the axis of the valve body (3) channel. The outer annular surface is pressed against the inner wall of the valve seat placement cavity, and there is a clearance fit between the outer circular surface of the valve seat (7) and the inner wall of the valve seat placement cavity.

2. The cryogenic butterfly valve capable of online maintenance according to claim 1, characterized in that: The butterfly plate (5) has a conical sealing surface and a valve seat (7). The conical sealing surface consists of an inclined surface located at the valve stem installation position and an elliptical conical surface that gradually extends on both sides of the inclined surface.

3. The cryogenic butterfly valve capable of online maintenance according to claim 2, characterized in that: An elastic rubber O-ring (28) is provided inside the C-type elastic ring (8).

4. The cryogenic butterfly valve capable of online maintenance according to claim 3, characterized in that: A composite sealing structure is formed by setting an energy storage sealing ring (10) and a rubber sealing gasket (29) between the valve cover (11) and the valve body (3). The energy storage sealing ring (10) is composed of an O-ring set in the inner cavity of the U-shaped rubber lip sealing ring, and the opening of the U-shaped rubber lip sealing ring is set towards its inner ring surface.

5. The cryogenic butterfly valve capable of online maintenance according to claim 1, 2, 3, or 4, characterized in that: The packing sealing device consists of a second energy storage sealing ring (15), an integrated bearing packing pad (16), packing (17), and a packing gland (18) forming a composite sealing structure. The second energy storage sealing ring (15) is composed of a U-shaped sealing ring and a rubber O-ring. The U-shaped sealing ring is installed between the outer circle of the upper valve stem (13) and the bottom surface of the stuffing box of the bracket (12), with its U-shaped opening facing downward. The rubber O-ring is embedded in the inner cavity of the U-shaped sealing ring. The integrated bearing packing pad (16) and the packing (17) are sequentially pressed onto the U-shaped sealing ring by the packing gland (18). The packing gland (18) is installed on the upper end face of the bracket (12) by bolts and a butterfly spring (19).

6. The cryogenic butterfly valve capable of online maintenance according to claim 5, characterized in that: A drainage groove (25) is provided on the upper end face of the support (12). The drainage groove (25) is composed of several radial inclined grooves arranged in the circumferential direction on the upper end face of the support (12). A drip tray (14) is provided on the support (12) below the drainage groove (25).

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