Anti-cavitation self-adapting seal cryogenic ball valve

Abstract

The application provides an anti-cavitation self-adaptive sealing low-temperature ball valve, which comprises a valve body, a valve rod penetrating the side of the valve body, a ball valve core arranged in the valve body and connected with the end of the valve rod, and a floating valve seat assembly in sealing cooperation with the ball valve core, the valve rod is used for driving the ball valve core to rotate, the ball valve core comprises a body and a main flow through hole penetrating the body, and a hierarchical flow guide groove group is arranged at the outer wall of the outlet side of the body, and the hierarchical flow guide groove group is located at the outer edge of the outlet end of the main flow through hole; the application can slow down the small opening degree jet concentration and near-wall cavitation erosion.

Description

Technical Field

[0001] This invention relates to the field of cryogenic valves, and in particular to a cavitation-resistant adaptive sealing cryogenic ball valve. Background Technology

[0002] Cryogenic ball valves are widely used in systems for conveying, shutting off, and regulating flow of cryogenic media such as liquefied natural gas, liquid nitrogen, and liquid hydrogen. When the ball valve is in a small opening and high pressure differential condition, the medium flows through the narrow flow gap between the ball valve core and the valve seat, causing the flow velocity to rise rapidly and the local pressure to drop, which easily generates cavitation bubbles. After the cavitation bubbles enter the downstream pressure recovery area, they collapse, which may cause erosion of the valve seat, valve body flow channel, and sealing mating surfaces. At the same time, the material contraction caused by the low temperature environment and the wear of the sealing surface caused by long-term opening and closing can easily change the sealing specific pressure between the ball valve core and the valve seat, affecting the sealing reliability of the ball valve.

[0003] Existing cryogenic ball valves typically employ floating seats, elastic preload components, or spring-loaded sealing rings to compensate for cryogenic contraction and wear on the sealing surface. To address the issues of high-speed jetting and cavitation under small opening conditions, existing technologies also utilize structures such as throttling orifices, multi-stage orifice plates, labyrinth channels, stepped grooves, or gradually expanding channels to divert, reduce pressure, dissipate energy, and restore pressure to the medium. Some ball valves improve flow change characteristics during the initial opening stage by changing the shape of the valve core's flow port or by incorporating auxiliary flow structures.

[0004] However, the existing valve core guiding structure, valve seat energy dissipation structure, and downstream diffusion structure are usually independent of each other. Some designs also require the addition of separate throttling or diffusion components, which increases the complexity of the valve structure and its processing and assembly. In the initial stage of ball valve opening, the flow area may still change rapidly within a short rotation stroke, forming a high-speed jet with a concentrated direction. If the medium after throttling lacks continuous staged energy dissipation, flow direction adjustment, and gradual pressure recovery, cavitation bubbles may still develop and collapse in the valve seat or valve body near the wall. Therefore, how to maintain the compact structure and reliable sealing of the cryogenic ball valve while performing staged adjustment of the flow area during the opening process and continuous energy dissipation and pressure recovery of the high-speed medium after throttling is a problem that still needs to be solved by existing technology. Summary of the Invention

[0005] The purpose of this invention is to provide an anti-cavitation adaptive sealing cryogenic ball valve that can mitigate jet concentration at small openings and near-wall cavitation erosion.

[0006] To solve the above-mentioned technical problems, the present invention provides an anti-cavitation adaptive sealing cryogenic ball valve, including a valve body, a valve stem passing through the side of the valve body, a ball valve core disposed inside the valve body and connected to the end of the valve stem, and a floating valve seat assembly sealingly cooperating with the ball valve core. The valve stem is used to drive the ball valve core to rotate. The ball valve core includes a body and a main flow hole penetrating the body, and a graded flow guide groove group is provided on the outer wall of the outlet side of the body. The graded flow guide groove group is located at the outer edge of the outlet end of the main flow hole.

[0007] Furthermore, the graded flow guide channel group includes a primary pre-start flow guide channel, a flow guide buffer pressure equalization zone, and a secondary flow boosting and regulating channel arranged sequentially along the rotation direction of the ball valve core. Both the primary pre-start flow guide channel and the secondary flow boosting and regulating channel extend circumferentially along the outlet end of the main flow through hole in an arc-shaped groove.

[0008] Furthermore, the floating valve seat assembly includes a seat body disposed between the valve body and the ball valve core. The seat body has a flow port that matches the main flow through hole. The edge of the flow port is correspondingly disposed with the graded flow guide groove group to form a graded flow gap. When the ball valve core rotates from the closed position to the open position, the first-stage pre-start flow guide groove, the flow guide buffer equalization zone, and the second-stage flow boosting adjustment groove sequentially enter the flow port range of the seat body, and the flow cross-sectional area of ​​the graded flow gap increases sequentially.

[0009] Furthermore, the maximum cross-sectional area of ​​the primary pre-start guide channel is smaller than the maximum cross-sectional area of ​​the secondary flow boosting and regulating channel, and the cross-sectional area of ​​the guide buffer pressure equalization zone gradually increases along the direction from the primary pre-start guide channel toward the secondary flow boosting and regulating channel, so that the two sides of the guide buffer pressure equalization zone are smoothly connected to the primary pre-start guide channel and the secondary flow boosting and regulating channel respectively.

[0010] Furthermore, the inner surface of the seat is provided with a graded energy dissipation zone, which includes several annular stepped grooves spaced apart along the direction of medium flow. An annular transition step is formed between two adjacent annular stepped grooves, and the first annular stepped groove of the graded energy dissipation zone is located downstream of the outlet of the graded flow gap.

[0011] Furthermore, the inner surface of the seat is provided with a sealing and pressurizing area located upstream of the graded energy dissipation area. The sealing and pressurizing area is provided with an annular mounting groove. A C-shaped lip energy storage sealing ring that seals with the ball valve core is embedded in the annular mounting groove. The lip of the C-shaped lip energy storage sealing ring faces the high-pressure side of the medium, and an energy storage V-shaped spring is embedded in the C-shaped lip energy storage sealing ring.

[0012] Furthermore, the floating valve seat assembly also includes an elastic preload member disposed between the seat body and the valve body, the elastic preload member applying an axial preload force toward the ball valve core to the seat body.

[0013] Furthermore, the inner surface of the seat is provided with a swirling diffuser zone located downstream of the staged energy dissipation zone. The swirling diffuser zone includes a gradually expanding channel connected to the final stage annular stepped groove and several spiral guide grooves provided on the inner wall of the gradually expanding channel. The inner diameter of the gradually expanding channel gradually increases along the direction of medium flow, and the several spiral guide grooves extend spirally along the direction of medium flow. The inlet of each spiral guide groove is connected to the downstream of the final stage annular stepped groove.

[0014] Furthermore, the depth or cross-sectional area of ​​the spiral guide channel gradually decreases along the direction of medium flow, and the downstream section of the gradually expanding channel forms a pressure recovery section with a smooth inner wall, so that the downstream section of the gradually expanding channel is connected to the downstream channel of the valve body through the pressure recovery section.

[0015] Furthermore, the maximum width of the secondary flow-increasing regulating trough is greater than the maximum width of the primary pre-start guiding trough, and the maximum depth of the secondary flow-increasing regulating trough is greater than the maximum depth of the primary pre-start guiding trough.

[0016] The beneficial effects of this invention are as follows: 1. The graded flow guide groove group is set on the outer spherical surface of the outlet side of the ball body. When the ball valve core is opened, the first-stage pre-start flow guide groove, the flow guide buffer pressure equalization zone and the second-stage flow boosting adjustment groove enter the flow port range of the metal seat in sequence, so that the flow cross-sectional area of ​​the graded flow gap increases in sequence, which helps to slow down the sudden change of the flow area in the initial opening stage and reduce the degree of formation of concentrated high-speed jet.

[0017] 2. The edge of the flow outlet of the seat and the graded flow guide groove group together form a graded flow gap. The first-stage annular stepped groove is set downstream of the outlet of the graded flow gap. After the medium flows out of the graded flow gap, it enters the annular stepped grooves of each stage in sequence. Through diffusion, deflection and energy dissipation, the direct impact of the high-speed jet on the metal seat and downstream flow channel is reduced.

[0018] 3. After staged energy dissipation, the medium enters the swirling diffusion zone and forms a controlled swirling flow under the guidance of the spiral guide channel in the same direction. As the flow area of ​​the gradually expanding channel increases, the medium gradually decelerates and recovers its pressure. The spiral guide channel gradually transitions to zero upstream of the outlet of the gradually expanding channel, which can reduce the sudden flow change when the medium enters the pressure recovery section from the swirling section. This helps to reduce the risk of cavitation erosion in the valve seat and valve body near the wall.

[0019] 4. The elastic preload applies axial preload to the seat, and the energy-storing V-type spring provides initial sealing force to the C-type lip energy-storing seal ring. After the medium pressure enters the opening of the C-type lip energy-storing seal ring, it pushes the sealing lip to press against the ball valve core, which helps to compensate for low-temperature cold contraction and slight wear of the sealing surface, and maintains the sealing fit between the ball valve core and the valve seat. Attached Figure Description

[0020] Figure 1This is a three-dimensional structural diagram of the valve core of the graded flow guiding ball valve in this invention.

[0021] Figure 2 This is an overall axial sectional view of the cryogenic ball valve in this invention.

[0022] Figure 3 This is a partially enlarged cross-sectional view of the floating valve seat assembly in this invention.

[0023] Figure 4 This is a partially enlarged cross-sectional view of the graded energy dissipation zone and the swirling diffuser zone in this invention.

[0024] Reference numerals: 1. Valve body; 2. Pressure plate; 3. Valve stem; 4. Ball valve core; 41. Main flow through hole; 42. First-stage pre-start guide groove; 43. Second-stage flow boosting and regulating groove; 44. Guide buffer pressure equalization zone; 5. Elastic pre-tightening element; 6. Seat; 7. C-type lip-shaped energy storage seal ring; 8. Annular stepped groove; 9. Washer ring; 10. Energy storage V-type spring; 11. Gradually expanding flow channel; 12. Spiral guide groove. Detailed Implementation

[0025] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention are within the scope of protection of the present invention.

[0026] Those skilled in the art should understand that, in the disclosure of this invention, the terms "longitudinal," "lateral," "upper," "lower," "front," "rear," "left," "right," "vertical," "horizontal," "top," "bottom," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the above terms should not be construed as limiting this invention.

[0027] It is understood that the term "a" should be understood as "at least one" or "one or more", that is, in one embodiment, the number of an element can be one, while in another embodiment, the number of the element can be multiple, and the term "a" should not be understood as a limitation on the number.

[0028] like Figures 1-4The present invention provides an anti-cavitation adaptive sealing cryogenic ball valve, comprising a valve body 1, a valve stem 3 passing through the side of the valve body 1, a ball valve core 4 disposed inside the valve body 1 and connected to the end of the valve stem 3, and a floating valve seat assembly sealingly cooperating with the ball valve core 4. The valve stem 3 is used to drive the ball valve core 4 to rotate. The ball valve core 4 includes a body and a main flow hole 41 penetrating the body. The main flow hole 41 is used to connect the upstream flow channel and the downstream flow channel of the valve body 1 after the ball valve is opened. A graded flow guide groove group is provided on the outer wall of the outlet side of the body. The graded flow guide groove group is located on the outer edge of the outlet end of the main flow hole 41 and is not formed on the inner wall of the main flow hole 41.

[0029] In this scheme, the medium flow direction refers to the direction in which the medium flows from the upstream flow channel of the valve body 1 to the downstream flow channel; the outlet side of the ball valve core 4 refers to the side of the main flow through hole 41 facing the downstream flow channel of the valve body 1 when the ball valve is open; the opening direction of the ball valve core 4 refers to the rotation direction of the ball valve core 4 when it changes from the closed position to the open position.

[0030] Specifically, the ball valve is opened, closed and its flow is regulated by the valve stem 3 driving the ball valve core 4 to rotate. In the initial stage of opening the ball valve, the medium passes through the graded flow gap formed between the graded flow guide groove group and the floating valve seat assembly in stages, so that the flow cross-sectional area changes from small to large step by step, thereby reducing the sudden change of the flow area in the initial stage of opening, reducing the degree of formation of concentrated high-speed jet, and mitigating the concentration of small-opening jet and near-wall cavitation erosion.

[0031] In one embodiment of this solution, the graded flow guide groove group includes a first-stage pre-start flow guide groove 42, a flow guide buffer pressure equalization zone 44, and a second-stage flow boosting and regulating groove 43 arranged sequentially along the rotation direction of the ball valve core 4. The first-stage pre-start flow guide groove 42 and the second-stage flow boosting and regulating groove 43 both extend circumferentially along the outlet end of the main flow through hole 41 in an arc-shaped groove.

[0032] Specifically, the maximum cross-sectional area of ​​the primary pre-start guide channel 42 is smaller than that of the secondary flow boosting and regulating channel 43, and the cross-sectional area of ​​the guide buffer equalization zone 44 gradually increases along the direction from the primary pre-start guide channel 42 toward the secondary flow boosting and regulating channel 43, so that the two sides of the guide buffer equalization zone 44 are smoothly connected to the primary pre-start guide channel 42 and the secondary flow boosting and regulating channel 43 respectively, thereby reducing the sudden flow changes caused by the change in the flow cross section when the medium enters the secondary flow boosting and regulating channel 43 from the primary pre-start guide channel 42.

[0033] In one embodiment of this solution, the maximum width of the secondary flow-increasing regulating groove 43 is greater than the maximum width of the primary pre-start guiding groove 42, and the maximum depth of the secondary flow-increasing regulating groove 43 is greater than the maximum depth of the primary pre-start guiding groove 42, so as to ensure that the cross-sectional area of ​​the staged flow gap increases further and more gradually when the ball valve core 4 continues to rotate.

[0034] Preferably, both the bottom and sidewall of the primary pre-start guide channel 42 and the secondary flow enhancement and regulating channel 43 are provided with arc transition sections to reduce local flow separation and pressure changes at sharp corners within the channels.

[0035] In one embodiment of this solution, when the ball valve core 4 is in the closed position, the graded flow guide groove group does not intersect with the annular sealing contact area between the ball valve core 4 and the valve seat, and a continuous spherical sealing area is maintained between the outer periphery of the graded flow guide groove group and the body, so that the setting of the graded flow guide groove group does not affect the annular sealing fit in the closed state of the ball valve.

[0036] Preferably, the floating valve seat assembly includes a seat 6 disposed between the valve body 1 and the ball valve core 4. The seat 6 has a flow port that matches the main flow through hole 41. The edge of the flow port is correspondingly disposed with the graded flow guide groove group to form a graded flow gap. When the ball valve core 4 rotates from the closed position to the open position, the first-stage pre-start flow guide groove 42, the flow guide buffer equalization zone 44 and the second-stage flow boosting adjustment groove 43 sequentially enter the flow port range of the seat 6, and the flow cross-sectional area of ​​the graded flow gap increases sequentially.

[0037] Specifically, when the ball valve core 4 begins to open, the first-stage pre-opening guide groove 42 first enters the flow port range of the seat body 6. The first-stage pre-opening guide groove 42 and the edge of the flow port together form a small flow cross section, allowing the medium to pass through at a small flow rate in the initial stage of ball valve opening. As the ball valve core 4 continues to rotate, the guide buffer equalization zone 44 gradually enters the flow port range. As the cross-sectional area of ​​the guide buffer equalization zone 44 gradually increases along the opening direction, the flow cross-sectional area of ​​the staged flow gap increases accordingly. As the ball valve core 4 rotates further, the second-stage flow-increasing regulating groove 43 enters the flow port range, and the flow cross-sectional area of ​​the staged flow gap further increases. As the ball valve core 4 continues to rotate, the main flow through hole 41 gradually connects with the upstream and downstream flow channels of the valve body 1 until the ball valve reaches the fully open state.

[0038] In one embodiment of this solution, the inner surface of the seat 6 is provided with a graded energy dissipation zone. The graded energy dissipation zone includes several annular stepped grooves 8 spaced apart along the medium flow direction. An annular transition step is formed between two adjacent annular stepped grooves 8. The first annular stepped groove 8 of the graded energy dissipation zone is located downstream of the outlet of the graded flow gap and is used to receive the medium flowing out from the graded flow gap.

[0039] Specifically, after the medium flows out of the staged flow gap, it enters the first-stage annular stepped groove 8, and under the action of each stage of the annular stepped groove 8 and the annular transition step, it undergoes diffusion, turning and local backflow. As the medium passes through each stage of the annular stepped groove 8 in sequence, its flow energy is dissipated step by step, thereby reducing the direct impact of the concentrated jet on the seat 6 and the downstream flow channel of the valve body 1.

[0040] In one embodiment of this solution, the annular stepped groove 8 has 4 levels. In other embodiments, the annular stepped groove 8 can be set to 4-6 levels. The groove depth of each level of the annular stepped groove 8 increases gradually along the medium flow direction, and the groove depth of the last level of the annular stepped groove 8 is 2.5-4 times the groove depth of the first level of the annular stepped groove 8. The groove depth of the annular stepped groove 8 can be 0.6mm-8.0mm, the groove width can be 1.0mm-5.0mm, the axial distance between two adjacent levels of the annular stepped groove 8 can be 2.0mm-8.0mm, and the cross-section of the annular stepped groove 8 can be rectangular or trapezoidal. The bottom of the annular stepped groove 8 and the sidewall of the groove are provided with an arc transition part to reduce local flow separation and pressure change at sharp edges.

[0041] Preferably, the inner surface of the seat 6 is provided with a sealing and pressurizing area located upstream of the graded energy dissipation area. The sealing and pressurizing area is provided with an annular mounting groove. A C-shaped lip-shaped energy storage sealing ring 7 is embedded in the annular mounting groove and seals with the ball valve core 4. The lip of the C-shaped lip-shaped energy storage sealing ring 7 faces the high-pressure side of the medium, and its opening is connected to the high-pressure side of the medium. Furthermore, an energy storage V-shaped spring 10 is embedded in the C-shaped lip-shaped energy storage sealing ring 7.

[0042] Specifically, the energy-storing V-shaped spring 10 can be made of 304L or 316L austenitic stainless steel wire and provides initial preload to the C-shaped lip energy-storing seal ring 7. Under no-pressure or low-pressure conditions, the elastic restoring force of the energy-storing V-shaped spring 10 keeps the C-shaped lip energy-storing seal ring 7 in contact with the ball valve core 4 to form an initial seal. After the medium pressure enters the opening of the C-shaped lip energy-storing seal ring 7, it pushes the sealing lip toward the ball valve core 4, making the sealing lip further press against the ball valve core 4, thereby increasing the sealing contact pressure to compensate for minor wear on the sealing surface and changes in sealing pressure.

[0043] Preferably, the floating valve seat assembly further includes an elastic preload member 5 disposed between the seat body 6 and the valve body 1. The elastic preload member 5 applies an axial preload force toward the ball valve core 4 to the seat body 6, so that the seat body 6 can float axially relative to the valve body 1 to compensate for the change in fit clearance caused by low temperature shrinkage and wear of the sealing surface. The elastic preload member 5 can be a disc spring, a disc spring assembly or a wave spring.

[0044] Preferably, the floating valve seat assembly further includes a pressure plate 2 disposed on the side of the seat body 6 facing away from the ball valve core 4, the pressure plate 2 being used to axially limit the floating valve seat assembly; a gasket 9 is also provided between the seat body 6 and the valve body 1, for supporting and limiting the floating valve seat assembly.

[0045] In one embodiment of this solution, the seat 6 is made of 316L austenitic stainless steel, and the ball valve core 4 is made of 304, 316 or 316L austenitic stainless steel; the seat 6 and the ball valve core 4 are preferably made of the same material or materials with similar coefficients of thermal expansion, so as to reduce the difference in sealing fit dimensions caused by low temperature changes.

[0046] Preferably, the inner surface of the seat 6 is provided with a swirling diffuser zone located downstream of the staged energy dissipation zone. The swirling diffuser zone includes a gradually expanding channel 11 connected to the final stage annular stepped groove 8 and a plurality of spiral guide grooves 12 provided on the inner wall of the gradually expanding channel 11. The inner diameter of the gradually expanding channel 11 gradually increases along the direction of medium flow, and the plurality of spiral guide grooves 12 extend spirally along the direction of medium flow. The inlet of each spiral guide groove 12 is connected to the downstream of the final stage annular stepped groove 8.

[0047] Specifically, a number of spiral guide channels 12 are arranged at circumferential intervals along the gradually expanding channel 11 and extend in the same direction of rotation. The number of spiral guide channels 12 can be 4-8. After the medium is energized by stage, it enters the spiral guide channel 12 and obtains a tangential velocity around the central axis of the gradually expanding channel 11 under the guidance of the spiral guide channel 12 and forms a rotating flow. As the flow area of ​​the gradually expanding channel 11 gradually increases, the medium velocity gradually decreases and the pressure gradually recovers.

[0048] In one embodiment of this solution, the depth or cross-sectional area of ​​the spiral guide channel 12 gradually decreases along the medium flow direction and transitions to zero upstream of the outlet of the gradually expanding channel 11, so that the swirling intensity gradually decreases, thereby forming a pressure recovery section with a smooth inner wall in the downstream section of the gradually expanding channel 11. The downstream section of the gradually expanding channel 11 is connected to the downstream flow channel of the valve body 1 through the pressure recovery section, reducing the flow abrupt change when the medium enters the pressure recovery section from the swirling section. The gradually expanding channel 11 can adopt a conical gradually expanding structure, and the downstream end of the gradually expanding channel 11 is connected to the downstream flow channel of the valve body 1 through an arc transition surface, so as to reduce the flow separation caused by the change of the flow channel cross-section.

[0049] The working process of this scheme is as follows: When the ball valve is in the closed state, the elastic preload 5 pushes the seat 6 towards the ball valve core 4, so that the C-type lip energy storage seal 7 is in contact with the sealing surface of the ball valve core 4. The energy storage V-type spring 10 provides the initial sealing force to the C-type lip energy storage seal 7. After the medium pressure enters the opening, it further pushes the sealing lip to press against the ball valve core 4. At the same time, the continuous spherical sealing area retained on the outer periphery of the graded flow guide groove group forms a sealing fit with the C-type lip energy storage seal 7. When the ball valve starts to open, the valve stem 3 drives the ball valve core 4 to rotate. The first-stage pre-opening flow guide groove 42, the flow guide buffer equalization zone 44 and the second-stage flow boosting regulating groove 43 enter the flow port range of the seat 6 in sequence. The flow cross-sectional area of ​​the graded flow gap gradually increases. Then the main flow through hole 41 gradually connects with the flow channel of the valve body 1. After the medium flows out of the graded flow gap, it enters the graded energy dissipation zone. In the annular stepped groove 8 of each stage... The medium undergoes diffusion, reversal, and energy dissipation within the valve body before entering the swirling diffusion zone. Guided by the spiral guide groove 12, it forms a rotating flow and gradually decelerates and recovers pressure as the flow area of ​​the gradually expanding channel 11 increases. Finally, it flows out into the pressure recovery section with a smooth inner wall. Thus, during the opening of the ball valve, the medium sequentially undergoes graded guidance, stepped energy dissipation, swirling regulation, and gradual pressure recovery. This helps to reduce the impact of high-speed medium on the downstream flow channels of the seat 6 and valve body 1, and reduces the risk of erosion caused by the collapse of cavitation bubbles in the near-wall area. During low-temperature operation, the elastic preload 5 compensates for the change in the fit clearance between the valve body 1, the ball valve core 4, and the seat 6 due to cold contraction through the axial floating of the seat 6. The C-shaped lip energy storage seal 7 compensates for the slight wear of the sealing surface and the change in sealing specific pressure through the elastic restoring force of the energy storage V-shaped spring 10 and the auxiliary densification effect of the medium pressure, thus maintaining the reliability of the seal.

[0050] This invention is not limited to the preferred embodiments described above. Anyone can derive other products in various forms under the guidance of this invention. However, regardless of any changes in shape or structure, any technical solution that is the same as or similar to this application falls within the protection scope of this invention.

Claims

1. A cavitation-resistant adaptive sealing cryogenic ball valve, characterized in that: The valve body includes a valve body (1), a valve stem (3) passing through the side of the valve body (1), a ball valve core (4) located inside the valve body (1) and connected to the end of the valve stem (3), and a floating valve seat assembly that seals with the ball valve core (4). The valve stem (3) is used to drive the ball valve core (4) to rotate. The ball valve core (4) includes a body and a main flow hole (41) passing through the body. A graded flow guide groove group is provided on the outer wall of the outlet side of the body. The graded flow guide groove group is located at the outer edge of the outlet end of the main flow hole (41).

2. The anti-cavitation adaptive sealing cryogenic ball valve according to claim 1, characterized in that: The graded flow guide groove group includes a first-stage pre-start flow guide groove (42), a flow guide buffer equalization zone (44), and a second-stage flow boosting and regulating groove (43) arranged sequentially along the rotation direction of the ball valve core (4). The first-stage pre-start flow guide groove (42) and the second-stage flow boosting and regulating groove (43) both extend circumferentially along the outlet end of the main flow through hole (41) in an arc-shaped groove.

3. The anti-cavitation adaptive sealing cryogenic ball valve according to claim 2, characterized in that: The floating valve seat assembly includes a seat (6) disposed between the valve body (1) and the ball valve core (4). The seat (6) has a flow port that matches the main flow through hole (41). The edge of the flow port is correspondingly disposed with the graded flow guide groove group to form a graded flow gap. When the ball valve core (4) rotates from the closed position to the open position, the first-stage pre-start flow guide groove (42), the flow guide buffer equalization zone (44), and the second-stage flow boosting adjustment groove (43) sequentially enter the flow port range of the seat (6), and the flow cross-sectional area of ​​the graded flow gap increases sequentially.

4. The anti-cavitation adaptive sealing cryogenic ball valve according to claim 2, characterized in that: The maximum cross-sectional area of ​​the first-stage pre-start guide channel (42) is smaller than that of the second-stage flow-increasing regulating channel (43), and the cross-sectional area of ​​the guide buffer equalization zone (44) gradually increases along the direction from the first-stage pre-start guide channel (42) toward the second-stage flow-increasing regulating channel (43), so that the two sides of the guide buffer equalization zone (44) are smoothly connected to the first-stage pre-start guide channel (42) and the second-stage flow-increasing regulating channel (43), respectively.

5. The anti-cavitation adaptive sealing cryogenic ball valve according to claim 3, characterized in that: The inner surface of the seat (6) is provided with a graded energy dissipation zone. The graded energy dissipation zone includes several annular stepped grooves (8) spaced apart along the direction of medium flow. An annular transition step is formed between two adjacent annular stepped grooves (8). The first annular stepped groove (8) of the graded energy dissipation zone is located downstream of the outlet of the graded flow gap.

6. The anti-cavitation adaptive sealing cryogenic ball valve according to claim 5, characterized in that: The inner surface of the seat (6) is provided with a sealing and pressurizing zone located upstream of the graded energy dissipation zone. The sealing and pressurizing zone is provided with an annular mounting groove. A C-shaped lip energy storage sealing ring (7) that seals with the ball valve core (4) is embedded in the annular mounting groove. The lip of the C-shaped lip energy storage sealing ring (7) faces the high pressure side of the medium, and an energy storage V-shaped spring (10) is embedded in the C-shaped lip energy storage sealing ring (7).

7. The anti-cavitation adaptive sealing cryogenic ball valve according to claim 3, characterized in that: The floating valve seat assembly also includes an elastic preload member (5) disposed between the seat body (6) and the valve body (1), the elastic preload member (5) applying an axial preload force toward the ball valve core (4) to the seat body (6).

8. The cavitation-resistant adaptive sealing cryogenic ball valve according to claim 5, characterized in that: The inner surface of the seat (6) is provided with a swirling diffuser zone located downstream of the staged energy dissipation zone. The swirling diffuser zone includes a gradually expanding channel (11) connected to the final stage annular stepped groove (8) and several spiral guide grooves (12) provided on the inner wall of the gradually expanding channel (11). The inner diameter of the gradually expanding channel (11) gradually increases along the direction of medium flow, and the several spiral guide grooves (12) extend spirally along the direction of medium flow. The inlet of each spiral guide groove (12) is connected to the downstream of the final stage annular stepped groove (8).

9. The anti-cavitation adaptive sealing cryogenic ball valve according to claim 8, characterized in that: The depth or cross-sectional area of ​​the spiral guide groove (12) gradually decreases along the direction of medium flow, and the downstream section of the gradually expanding channel (11) forms a pressure recovery section with a smooth inner wall, so that the downstream section of the gradually expanding channel (11) is connected to the downstream channel of the valve body (1) through the pressure recovery section.

10. The cavitation-resistant adaptive sealing cryogenic ball valve according to claim 2, characterized in that: The maximum width of the secondary flow-increasing regulating trough (43) is greater than the maximum width of the primary pre-start guiding trough (42), and the maximum depth of the secondary flow-increasing regulating trough (43) is greater than the maximum depth of the primary pre-start guiding trough (42).

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