High-temperature and high-pressure hard sealing three-eccentric center butterfly valve

Abstract

The utility model discloses a high-temperature and high-pressure hard sealing three-eccentric center butterfly valve, and relates to the field of butterfly valves. In petrochemical engineering, electric power and other high-temperature and high-pressure industrial scenes, a traditional butterfly valve has the problems of sealing failure, large friction torque, influence of thermal expansion on pre-tightening force and the like. The three-eccentric butterfly valve comprises a valve body, a valve rod, a valve plate, a valve seat and a bottom end cover, the axis of the valve plate, the axis of the valve rod and the sealing face of the valve seat form a three-eccentric structure, the valve plate comprises a plate body, a metal winding gasket, an elastic sealing ring and a pressing ring, and the outer circumferential face of the elastic sealing ring and the inner circumferential face of the valve seat serve as sealing faces for closing the butterfly valve. Zero-friction contact type sealing is achieved in the closing process of the valve through the three-eccentric structure, the sealing life is greatly prolonged, the opening and closing torque is reduced, the leakage problem caused by uneven sealing and machining errors of a traditional butterfly valve is solved through the double-sealing combination of the metal winding gasket and the elastic sealing ring, and the sealing performance of the butterfly valve is improved. The sealing stability and reliability are effectively improved, and the service life is prolonged.

Description

Technical Field

[0001] This utility model relates to the field of butterfly valves, and in particular to a high-temperature, high-pressure hard-seal triple eccentric butterfly valve. Background Technology

[0002] Butterfly valves are widely used in high-temperature and high-pressure industries such as petrochemicals and power generation. However, traditional butterfly valves suffer from numerous technical bottlenecks. While soft-seal butterfly valves offer good sealing performance, their temperature resistance is poor, and they are prone to aging and carbonization leading to leakage at temperatures above 200℃. Hard-seal butterfly valves, although resistant to high temperatures, are prone to wear grooves due to high friction on the sealing surface during opening and closing, increasing the leakage rate. Single-eccentric or double-eccentric butterfly valves, with the valve plate and seat in full contact, result in high frictional torque, high drive energy consumption, and are prone to damaging the drive system. Simultaneously, the difference in thermal expansion between different materials at high temperatures reduces the sealing preload, causing leakage. Existing improvement solutions, such as optimized designs of some triple-eccentric structures, lack error compensation mechanisms, resulting in poor actual sealing performance. Floating seat technology is limited by the high-temperature performance of springs and is difficult to adapt to high-pressure environments. Composite sealing materials have reliability issues in special media. Therefore, there is an urgent need for a butterfly valve technology that can achieve zero leakage, low-friction opening and closing, and convenient maintenance under high-temperature and high-pressure conditions to meet the stringent requirements of industrial applications. Utility Model Content

[0003] The technical problem to be solved and the technical task proposed by this utility model is to improve and refine the existing technical solutions, and to provide a high-temperature and high-pressure hard-seal triple eccentric butterfly valve, with the aim of reducing the opening and closing torque and improving the sealing stability under high-temperature and high-pressure conditions. To this end, this utility model adopts the following technical solution.

[0004] A high-temperature, high-pressure hard-seal triple-eccentric butterfly valve includes a valve body, a valve stem, a valve plate, a valve seat, and a bottom cover. The valve plate axis is eccentric to the valve stem axis, the valve stem axis is eccentric to the center of the valve body, and the valve seat sealing surface forms an inclined angle with the valve plate sealing surface, thus forming a triple-eccentric structure. The valve plate includes a plate body, a first metal spiral wound gasket, an elastic sealing ring, and a pressure ring. The first metal spiral wound gasket is embedded in a surrounding sealing groove provided in the plate body. The elastic sealing ring is provided on the surrounding step on the groove opening side of the surrounding sealing groove. The elastic sealing ring presses against the first metal spiral wound gasket. The outer circumferential surface of the elastic sealing ring and the inner circumferential surface of the valve seat serve as the sealing surface for the butterfly valve to close. The pressure ring presses against the elastic sealing ring and is fixed to the plate body by fasteners. By creating a spatial triple eccentric structure, a "zero-friction" contact seal is achieved during valve closure, avoiding premature wear between the sealing surfaces of traditional hard-seal butterfly valves. This significantly extends the seal life and reduces the opening and closing torque. The dual sealing combination of a first metal spiral wound gasket and an elastic sealing ring, where the specially designed metal spiral wound gasket performs the main sealing function under high temperature and high pressure conditions and the elastic sealing ring provides adaptive deformation compensation, solves the leakage problems caused by uneven sealing and processing errors in traditional butterfly valves. This achieves a reliable sealing effect that combines soft and hard seals, effectively improving sealing stability and reliability, and extending service life.

[0005] As a preferred technical means: the valve body is provided with a surrounding retaining ring extending towards the center of its inner flow channel. One side of the valve seat abuts against the surrounding retaining ring, and a rectangular sealing groove is formed on the outer periphery between the two. A second metal-wound gasket is provided inside, and the valve seat presses against the second metal-wound gasket. On the other axial side of the valve seat, a liner and a three-part pressure ring are provided in sequence. The outer periphery of the three-part pressure ring is provided with a radially outward protruding embedding part, which matches the fixing ring groove on the inner sidewall of the flow channel of the valve body. The three-part pressure ring is provided with evenly distributed set screws, which tighten and press against the liner, so that the liner presses against and fixes the valve seat axially. The three-part pressure ring applies axial force through the set screws, so that the valve seat presses against the second metal-wound gasket, forming a hard seal between the valve seat and the valve body, which can withstand high pressure and has no leakage. The liner absorbs the thermal expansion difference between the valve seat and the valve body, maintaining a stable preload. The valve seat is installed using a three-part pressure ring + set screw configuration to ensure a stable preload at high temperatures and prevent the seal from loosening.

[0006] As a preferred technical approach, the plate body and the elastic sealing ring are positioned by a sealing ring reference pin. The sealing ring reference pin ensures the circumferential positioning accuracy between the elastic sealing ring and the plate body, avoiding localized leakage caused by misalignment of the sealing surfaces.

[0007] As a preferred technical means, the valve seat and valve body are positioned by a valve seat reference pin. This ensures the circumferential positional accuracy of the valve seat and valve body, guarantees the stability of the triple eccentric geometric accuracy, and improves sealing stability.

[0008] As a preferred technical approach: the upper end of the bottom cover has an upward-facing boss in the middle, which mates with the valve stem bottom hole at the lower end of the valve body. A third metal spiral wound gasket is provided on the outer circumferential stepped surface of the boss. After the bottom end cover is connected and fixed to the lower end of the valve body, the third metal spiral wound gasket is compressed. The third metal spiral wound gasket forms a hard seal between the bottom end cover and the valve body, which can withstand high temperature and high pressure, avoiding the aging problem of traditional rubber seals. The embedded structure of the boss and the valve stem bottom hole effectively improves the structural stability and reliability, and can better reduce the risk of leakage.

[0009] As a preferred technical means: the valve stem hole in the valve body is provided with a bushing, and the valve stem rotatably engages with the bushing. The bushing includes multiple upper bushings, two middle bushings, and multiple lower bushings. The two middle bushings are respectively located on the upper and lower sides of the flow channel of the valve body. A portion of each middle bushing extends into the flow channel, and the other portion is interference-fitted with the valve body. The upper bushing is located above the middle bushing on the upper side of the flow channel and below the sealing packing assembly located at the upper end of the valve body. The lower bushing is located below the middle bushing on the lower side of the flow channel. The valve stem, supported by the bushing, can enhance the valve stem support rigidity, reduce valve plate sway, improve valve adjustment accuracy, reduce the resistance torque of valve stem rotation, and by setting the bushings in an upper, middle, and lower structure, they can be replaced individually, reducing maintenance costs. Furthermore, suitable materials can be selected for different parts to better improve performance.

[0010] As a preferred technical means: the diameter of the valve stem bottom hole is larger than the diameter of the valve stem bore, forming an inverted stepped hole. A thrust washer, a thrust ring, and a thrust bearing are provided at the lower end of the valve stem below the lower bushing. The thrust washer, thrust ring, and thrust bearing are located in the valve stem bottom hole. An inverted annular step is provided on the lower inner side of the thrust ring. The outer ring of the thrust bearing is interference-fitted with the side wall of the inverted annular step. The inner ring of the thrust bearing is embedded in the annular bearing groove at the lower end of the valve stem, with its inner circumference interference-fitted with the annular bearing groove. The thrust structure can withstand and transmit the axial load of the valve stem, ensuring stable valve stem operation and optimizing the overall mechanical properties of the valve. Through the combination of the thrust washer, thrust ring, and thrust bearing, it directly withstands the axial thrust or tension generated by the medium pressure and its own weight during the opening and closing process of the valve stem, preventing the valve stem from axial movement or displacement due to axial force.

[0011] As a preferred technical means, the valve stem and valve plate are connected by a flat key and two cylindrical pins for positioning. The two cylindrical pins are arranged parallel to the axial direction of the valve stem, the length direction of the flat key is consistent with the axial direction of the valve stem, and the end face of the flat key is perpendicular to the axial direction of the valve plate. The flat key achieves a radial rigid connection, ensuring that the valve stem and valve plate rotate synchronously. By setting the double cylindrical pins, the relative circumferential position of the valve plate and valve stem is precisely fixed, preventing the assembly misalignment of the triple eccentric structure.

[0012] As a preferred technical means, the sealing packing assembly, from bottom to top, includes a packing pad, a sealing packing group, a packing gland, and a packing pressure plate. The packing pad and the sealing packing group are located in the stuffing box groove on the outer periphery of the valve stem at the upper end of the valve body. The lower part of the packing gland is embedded in the stuffing box groove and presses the sealing packing group tightly. The packing pressure plate presses the packing gland downwards and is fastened to the upper end of the valve body by fully threaded studs and nuts. A spring washer is provided between the nut and the packing pressure plate. The sealing packing assembly achieves axial sealing of the valve stem, and the spring washer continuously provides axial force to compensate for packing wear, maintain sealing pressure, and achieve a long-term effective sealing effect.

[0013] Beneficial effects: The triple-eccentric structure creates a spatial triple-eccentric seal, achieving a "zero-friction" contact seal during valve closure. This avoids premature wear between the sealing surfaces of traditional hard-seal butterfly valves, significantly extending seal life and reducing opening and closing torque. The dual-seal combination of a first metal-wound gasket and an elastic sealing ring, with the specially designed gasket providing primary sealing under high-temperature and high-pressure conditions and the elastic sealing ring offering adaptive deformation compensation, solves the leakage problems caused by uneven sealing and processing errors in traditional butterfly valves. This achieves a reliable sealing effect combining soft and hard seals, effectively improving sealing stability and reliability, and extending service life. The valve seat installation uses a three-part pressure ring + set screw and gasket structure to ensure stable preload at high temperatures, preventing seal loosening and maintaining stable preload. The second metal-wound gasket forms a hard seal between the valve seat and valve body, effectively withstanding high pressure without leakage. Attached Figure Description

[0014] Figure 1 This is a schematic diagram of the structure of this utility model.

[0015] Figure 2 This is a schematic diagram of the main structure of this utility model.

[0016] Figure 3 yes Figure 2 Schematic diagram of sectional view AA.

[0017] Figure 4 yes Figure 2 Schematic diagram of the BB section.

[0018] Figure 5 yes Figure 3 Enlarged schematic diagram of section C.

[0019] Figure 6 yes Figure 3 Enlarged schematic diagram of section D in the middle.

[0020] In the diagram: 1. Valve body; 2. Valve stem; 3. Valve plate; 4. Valve seat; 5. Bottom end cap; 6. Cylindrical pin; 7. Packing gasket; 8. Sealing packing assembly; 9. Packing gland; 10. Packing gland; 11. Fully threaded stud; 12. Type I hexagonal nut; 13. Third spiral wound washer; 14. Thrust washer; 15. Thrust ring; 16. Thrust bearing; 17. Second spiral wound washer; 18. Bushing; 19. Three-part pressure ring; 20. Internal hexagonal socket head cap. 21. Set screw; 22. Valve seat reference pin; 23. Upper bushing; 24. Middle bushing; 25. Lower bushing; 26. Hex head bolt; 107. Spring washer; 108. Valve stem bottom hole; 109. Surrounding retaining ring part; 100. Flow channel; 201. Square connection structure; 302. Plate body; 303. First metal spiral wound washer; 304. Elastic sealing ring; 305. Pressure ring; 306. Sealing ring reference pin; 507. Boss; 1908. Embedded part. Detailed Implementation

[0021] The technical solution of this utility model will be further described in detail below with reference to the accompanying drawings.

[0022] Example 1

[0023] like Figures 1-5 As shown, a high-temperature, high-pressure hard-seal triple-eccentric butterfly valve includes a valve body 1, a valve stem 2, a valve plate 3, a valve seat 4, and a bottom cover 5. The axis of the valve plate 3 is eccentric to the axis of the valve stem 2, and the axis of the valve stem 2 is eccentric to the center of the valve body 1. The sealing surface of the valve seat 4 forms an inclined angle with the sealing surface of the valve plate 3, thus forming a triple-eccentric structure. The valve stem 2 and the valve plate 3 are positioned and connected by a flat key and two cylindrical pins 6. The two cylindrical pins 6 are arranged parallel to the axial direction of the valve stem 2 and are located in the lower region of the valve plate 3, precisely fixing the relative circumferential position of the valve plate 3 and the valve stem 2 to prevent assembly misalignment of the triple-eccentric structure. The flat key is located in the upper region of the valve plate 3. The length direction of the flat key is consistent with the axial direction of the valve stem 2, and the end face of the flat key is perpendicular to the axial direction of the valve plate 3, achieving a radial rigid connection through the flat key to ensure synchronous rotation of the valve stem 2 and the valve plate 3. A square connecting structure 201 is provided at the upper end of the valve stem 2, which is used to connect the actuator through a connecting short shaft. The valve plate 3 includes a plate body 301, a first spiral wound gasket 302, an elastic sealing ring 303, and a pressure ring 304. The first spiral wound gasket 302 is embedded in a surrounding sealing groove provided in the plate body 301. The elastic sealing ring 303 is provided on the surrounding step on the groove opening side of the surrounding sealing groove. The elastic sealing ring 303 presses against the first spiral wound gasket 302. The plate body 301 and the elastic sealing ring 303 are positioned by a sealing ring reference pin 305. The outer peripheral surface of the elastic sealing ring 303 and the inner peripheral surface of the valve seat 4 serve as the sealing surface for the butterfly valve to close. The pressure ring 304 presses against the elastic sealing ring 303 and is connected and fastened to the plate body 301 by an internal hex bolt and a spring washer 26.

[0024] like Figure 2 , Figure 3 As shown, the upper end of the valve body 1 is provided with a sealing packing assembly, which achieves axial sealing of the valve stem 2. The sealing packing assembly includes, from bottom to top, a packing pad 7, a sealing packing group 8, a packing gland 9, and a packing pressure plate 10. The packing pad 7 and the sealing packing group 8 are located in the stuffing groove on the outer periphery of the valve stem 2 at the upper end of the valve body 1. The lower part of the packing gland 9 is embedded in the stuffing groove and presses the sealing packing group 8. The packing pressure plate 10 presses the packing gland 9 downward and is fastened to the upper end of the valve body 1 by a fully threaded stud 11 and an I-type hexagonal nut 12. A spring washer 26 is provided between the I-type hexagonal nut 12 and the packing pressure plate 10. The spring washer 26 continuously provides axial force to compensate for packing wear, maintain sealing pressure, and achieve a long-term effective sealing effect.

[0025] like Figure 6 As shown, the upper end of the bottom cover 5 has an upward-facing boss 501 in the middle. The boss 501 is fitted into the valve stem bottom hole 101 at the lower end of the valve body 1. The embedded structure of the boss 501 and the valve stem bottom hole 101 can effectively improve the stability and reliability of the assembly structure. A third metal spiral wound washer 13 is provided on the outer peripheral stepped surface of the boss 501. The bottom end cover 5 and the lower end of the valve body 1 are connected and fixed by a spring washer 26 and a hexagonal head bolt 25. The enclosed internal space formed at the lower end serves as the valve stem bottom hole 101. After the connection and fixation, the third metal spiral wound washer 13 is compressed. The third metal spiral wound washer 13 forms a hard seal between the bottom end cover 5 and the valve body 1, which can withstand high temperature and high pressure and avoid the aging problem of rubber seals in the traditional bottom end cover 5 structure.

[0026] The diameter of the valve stem bottom hole 101 is larger than the diameter of the valve stem 2 hole in the valve body 1, forming an inverted stepped hole. The lower end of the valve stem 2 is equipped with a thrust washer 14, a thrust ring 15, and a thrust bearing 16. These components are located within the valve stem bottom hole 101. The lower inner side of the thrust ring 15 has an inverted annular step. The outer ring of the thrust bearing 16 is interference-fitted with the sidewall of the inverted annular step, and the inner ring of the thrust bearing 16 is embedded in the annular bearing groove at the lower end of the valve stem 2, with its inner circumference interference-fitted with the annular bearing groove. This thrust structure can withstand and transmit the axial load of the valve stem 2, ensuring stable operation of the valve stem 2. Through the combination of the thrust washer 14, thrust ring 15, and thrust bearing 16, it directly withstands the axial thrust or tension generated by the medium pressure and its own weight during the opening and closing process of the valve stem 2, preventing the valve stem 2 from shifting or displacing due to axial force.

[0027] During operation, the actuator drives the valve stem 2 to rotate. The valve stem 2 drives the valve plate 3 to rotate synchronously via the flat key and cylindrical pin 6. When the valve is open, due to the triple eccentric structure, the valve plate 3 disengages from the sealing surface of the valve seat 4 in the initial stage of rotation, avoiding friction. When closed, the valve plate 3 gradually approaches the valve seat 4, and finally the outer circumferential surface of the elastic sealing ring 303 fits against the inner circumferential surface of the valve seat 4. The first metal spiral wound gasket 302 and the elastic sealing ring 303 form a double seal, ensuring zero leakage. During operation, the axial force generated by the medium pressure is borne by the thrust structure composed of the thrust washer 14, the thrust ring 15, and the thrust bearing 16, preventing the valve stem 2 from moving. The spring washer 26 in the sealing packing assembly continuously compensates for packing wear, maintaining the axial sealing pressure of the valve stem 2. The third metal spiral wound gasket 13 of the bottom cover 5 ensures a hard seal at the bottom of the valve body 1, withstanding high temperature and high pressure. All components work together to achieve stable and reliable operation of the valve under harsh conditions.

[0028] The triple-eccentric structure formed by the axis of valve plate 3, the axis of valve stem 2, and the sealing surface of valve seat 4 achieves zero-friction contact when closed through geometric compensation, greatly extending the sealing life and reducing the opening and closing torque. The opening degree of the butterfly valve is adjusted by the rotation angle, and the butterfly valve is in the fully open state when rotated 90°. The opening degree of the butterfly valve changes linearly proportionally to the flow rate.

[0029] The dual sealing combination of the first metal spiral wound gasket 302 and the elastic sealing ring 303 provides adaptive deformation compensation, which solves the leakage problem caused by uneven sealing and processing errors in traditional butterfly valves. It achieves a reliable sealing effect that combines soft and hard sealing, effectively improves sealing stability and reliability, and extends service life.

[0030] Example 2

[0031] Unlike the above embodiment, as Figure 3 , 5As shown, the valve body 1 has a surrounding retaining ring portion 102 extending towards the center of its inner flow channel 103. One side of the valve seat 4 abuts against the surrounding retaining ring portion 102, and a rectangular sealing ring groove is formed on the outer periphery between the two. A second metal spiral wound gasket 17 is provided inside. The valve seat 4 presses the second metal spiral wound gasket 17. A three-opening pressure ring 19 is provided on the other axial side of the valve seat 4. A liner 18 is provided between the three-opening pressure ring 19 and the valve seat 4 as a protective element for the valve seat 4. The outer periphery of the three-section pressure ring 19 is provided with a radially outward protruding insert 1901. The insert 1901 is matched with the fixing ring groove on the inner side wall of the flow channel 103 of the valve body 1. The three-section pressure ring 19 achieves precise axial positioning by matching the insert 1901 with the fixing ring groove. The three-section pressure ring 19 is provided with evenly distributed hexagonal set screws 20. The three-section pressure ring 19 includes three pressure ring sections. Each pressure ring section is fastened and pressed with four hexagonal set screws 20 to compress the gasket, so that the gasket is axially pressed and fixed to the valve seat 4. The radial preload force applied to the gasket by the hexagonal set screws 20 is transmitted to the valve seat 4. In addition, every two adjacent pressure ring sections are limited and fixed by one hexagonal set screw 20, so as to achieve circumferential fastening of the three-section pressure ring 19. The valve seat 4 and the valve body 1 form an adjustable sealing system through the second metal spiral wound gasket 17, and simultaneously achieve axial fixation. The valve seat 4 and valve body 1 are positioned by the valve seat reference pin 21 to ensure the circumferential positional accuracy of the valve seat 4 and valve body 1, guarantee the stability of the triple eccentric geometric accuracy, and improve the sealing stability. The three-slit pressure ring 19 applies axial force through the internal hexagon set screw 20, causing the valve seat 4 to press against the second metal spiral wound gasket 17, forming a hard seal between the valve seat 4 and valve body 1, which can withstand high pressure and is leak-free. The gasket 18 absorbs the thermal expansion difference between the valve seat 4 and valve body 1, maintaining a stable preload. The valve seat 4 is installed using the three-slit pressure ring 19 + internal hexagon set screw 20 form to ensure a stable preload at high temperatures and prevent the seal from loosening.

[0032] Example 3

[0033] Unlike Embodiment 1 or 2 above, as Figure 3As shown, the valve stem 2 hole in the valve body 1 is provided with a bushing. The valve stem 2 is rotatably matched with the bushing. The bushing includes three upper bushings 22, two middle bushings 23 and two lower bushings 24. The two middle bushings 23 are located on the upper and lower sides of the flow channel 103 of the valve body 1, respectively. A part of each middle bushing 23 extends into the flow channel 103 and the other part is interference-fitted with the valve body 1. The three upper bushings 22 are located on the middle bushings 23 on the upper side of the flow channel 103. The three upper bushings 22 are arranged vertically in series and located below the sealing packing assembly provided at the upper end of the valve body 1. The lower bushings 24 are arranged vertically in series between the middle bushings 23 and the thrust washer on the lower side of the flow channel 103. The valve stem 2 is supported by a bushing, which can enhance the support rigidity of the valve stem 2, reduce the swing of the valve plate 3, improve the valve adjustment accuracy, reduce rotational friction, reduce the resistance torque of the valve stem 2 rotation, and by setting the bushing in an upper, middle and lower structure, it can be replaced individually, reducing maintenance costs. Furthermore, different parts can be made of compatible materials to better improve performance.

[0034] above Figure 1-6 The high-temperature and high-pressure hard-seal triple eccentric butterfly valve shown is a specific embodiment of this utility model, which has demonstrated the substantial features and progress of this utility model. According to actual use needs, equivalent modifications in shape, structure, etc. can be made to it under the guidance of this utility model, all of which are within the protection scope of this solution.

Claims

1. A high temperature and high pressure hard sealing triple offset butterfly valve, comprising a valve body, a valve stem, a valve plate, a valve seat and a bottom end cover, characterized in that: The valve plate axis is eccentric to the valve stem axis, the valve stem axis is eccentric to the valve body center, the valve seat sealing surface forms an inclined angle with the valve plate sealing surface, and a three-eccentric structure is formed; the valve plate includes a plate body, a first metal winding gasket, an elastic sealing ring, and a pressing ring, the first metal winding gasket is embedded in the surrounding sealing groove provided in the plate body, the elastic sealing ring is arranged on the surrounding step on the side of the groove opening, the elastic sealing ring presses the first metal winding gasket, the outer circumferential surface of the elastic sealing ring and the inner circumferential surface of the valve seat serve as the sealing surface when the butterfly valve is closed, and the pressing ring presses the elastic sealing ring, and the pressing ring is connected and fixed to the plate body by fasteners.

2. A high temperature and high pressure hard-sealed triple offset butterfly valve according to claim 1, characterized in that: The valve body is provided with a surrounding stop ring part extending to the center of the inner flow channel, one side of the valve seat abuts against the surrounding stop ring part, and the outer circumferential side between the valve seat and the surrounding stop ring part forms a rectangular sealing ring groove, a second metal winding gasket is arranged in the rectangular sealing ring groove, the valve seat presses the second metal winding gasket, the other side of the valve seat in the axial direction is sequentially provided with a lining gasket and a three-opening pressing ring, the outer circumferential surface of the three-opening pressing ring is provided with an embedded part protruding radially outward, the embedded part is matched with the fixed ring groove on the inner side wall of the flow channel of the valve body, the three-opening pressing ring is provided with uniformly distributed set screws, the set screws tightly press the lining gasket, and the lining gasket is axially tightly fixed to the valve seat.

3. A high temperature and high pressure hard-seal triple offset butterfly valve according to claim 1, characterized in that: The plate body and the elastic sealing ring are positioned by a sealing ring reference pin.

4. A high temperature and high pressure hard-sealed triple offset butterfly valve as claimed in claim 2, wherein: The valve seat and the valve body are positioned by a valve seat reference pin.

5. A high temperature and high pressure hard-sealed triple offset butterfly valve as claimed in claim 2, wherein: An upward boss is arranged in the middle of the upper end of the bottom end cover, the boss is matched with the valve stem bottom hole in the lower end of the valve body, a third metal winding gasket is arranged on the outer circumferential step surface of the boss, and the third metal winding gasket is tightly pressed after the bottom end cover is connected and fixed to the lower end of the valve body.

6. A high temperature and high pressure hard-sealed triple offset butterfly valve according to claim 5, characterized in that: A bushing is arranged in the valve stem hole in the valve body, the valve stem is rotationally matched with the bushing, the bushing includes a plurality of upper bushings, two middle bushings, and a plurality of lower bushings, the two middle bushings are respectively arranged at the upper side and the lower side of the flow channel of the valve body, a part of each middle bushing extends into the flow channel, and the other part is matched with the valve body in interference, the upper bushing is arranged on the upper surface of the middle bushing at the upper side of the flow channel and is located below the sealing packing assembly arranged on the upper end of the valve body, and the lower bushing is located below the middle bushing at the lower side of the flow channel.

7. A high temperature and high pressure hard-sealed triple offset butterfly valve as claimed in claim 6, characterized in that: The diameter of the valve stem bottom hole is greater than the diameter of the valve stem hole, forming an inverted step hole, the lower end of the valve stem is provided with a thrust washer, a thrust ring, and a thrust bearing below the lower bushing, the thrust washer, the thrust ring, and the thrust bearing are located in the valve stem bottom hole, the lower inner side of the thrust ring is provided with an inverted annular step, the outer ring of the thrust bearing is matched with the side wall of the inverted annular step in interference, and the inner ring of the thrust bearing is embedded in the surrounding bearing groove at the lower end of the valve stem, and the inner circumferential surface of the inner ring is matched with the surrounding bearing groove in interference.

8. A high temperature and high pressure hard-sealed triple offset butterfly valve according to claim 7, characterized in that: The valve stem and the valve plate are positioned and connected by a flat key and two cylindrical pins, the two cylindrical pins are arranged in parallel along the axial direction of the valve stem, the length direction of the flat key is consistent with the axial direction of the valve stem, and the end surface of the flat key is perpendicular to the axial direction of the valve plate.

9. A high temperature and high pressure hard-sealed triple offset butterfly valve as claimed in claim 8, characterized in that: The sealing packing assembly comprises, from bottom to top, a packing pad, a sealing packing group, a packing gland and a packing plate, the packing pad and the sealing packing group are arranged in a packing groove on the outer periphery of the valve stem at the upper end of the valve body, the lower part of the packing gland is embedded in the packing groove and presses the sealing packing group, the packing plate presses the packing gland downward, and the packing plate is fastened to the upper end of the valve body through all-thread studs and nuts, and a spring washer is arranged between the nuts and the packing plate.

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