Regulating valve applied to cryogenic working condition

Abstract

The regulating valve applied to the cryogenic working condition comprises a pneumatic execution part and a valve body, and an air cylinder seat of the pneumatic execution part is connected with a valve deck of the valve body through a locking plate; the pneumatic execution piece comprises a spring, a pneumatic piston and a connecting rod; the connecting rod is coaxially and fixedly connected with the valve core; the valve body comprises a valve body and a cold box which are welded and fixed; a valve cover is arranged at the near end of the cold box; filling assemblies are arranged in the valve deck in a central symmetry mode. A cold box inner cavity of the cold box is communicated with a valve body inner cavity of the valve body; the outer diameter of the convex block is equal to the inner diameter of the inner cavity of the valve body; the outer diameter of the output end of the valve element is equal to the inner diameter D1 of the valve seat and smaller than the diameter D2 of an inner cavity of the valve body. The diameter D2 of the valve body inner cavity is smaller than the diameter D3 of the cold box inner cavity. The valve body and the pipeline are connected in a welded mode, so that a risk point of external leakage of a medium is reduced; and a spring is adopted to be matched with an actuating mechanism of a pneumatic piston structure, so that higher thrust can be provided for valve sealing.

Description

Technical Field

[0001] This invention relates to the field of industrial automation control valve technology, and in particular to a regulating valve applied in cryogenic conditions. Background Technology

[0002] In cryogenic applications and marine applications, the sealing performance, flow capacity, and ease of maintenance of valves are crucial. Traditional control valves, such as those described in 207814472U and 210318514U, often face the risk of sealing failure and media leakage in cryogenic environments. Furthermore, maintenance is difficult in confined spaces (such as cold boxes or ship cabins), typically requiring disassembly of the entire valve or damage to the insulation layer, which is time-consuming and labor-intensive. In addition, improper flow channel design can lead to turbulence, reducing flow capacity. Therefore, designing a cryogenic control valve with high reliability, high flow capacity, and ease of online maintenance has significant engineering application value. Summary of the Invention

[0003] The purpose of this invention is to solve the above-mentioned problems existing in the prior art and to provide a regulating valve applicable to cryogenic conditions.

[0004] The objective of this invention is achieved through the following technical solution: A regulating valve for cryogenic applications includes a pneumatic actuator and a valve body. The cylinder seat of the pneumatic actuator is connected to the valve cover of the valve body via a locking plate. The pneumatic actuator includes at least a spring and a pneumatic piston disposed within a piston cylinder, and a connecting rod disposed within the cylinder seat. The output end of the connecting rod is coaxially and fixedly connected to a valve core disposed within the valve body. The pneumatic actuator drives the valve core to move relative to a valve seat disposed within the valve body. The valve body includes a welded and fixed valve body and a cryogenic... The cold box has a valve cover located near its end; a packing assembly is centrally symmetrically arranged inside the valve cover; the inner cavity of the cold box communicates with the inner cavity of the valve body to accommodate the valve core; a protrusion is integrally provided on the main body of the valve core near its output end, the outer diameter of the protrusion being approximately equal to the inner diameter of the inner cavity of the valve body; the outer diameter of the valve core output end is approximately equal to the inner diameter D1 of the valve seat and smaller than the diameter D2 of the inner cavity of the valve body; the diameter D2 of the inner cavity of the valve body is smaller than the diameter D3 of the inner cavity of the cold box.

[0005] Preferably, the input end of the valve core passes through the valve cover and the cylinder seat; the valve cover is cross-shaped, with its main body extending towards the cylinder seat and the cold box at both ends to form a neck structure, wherein the bottom of the neck structure located in the cold box has a step extending towards the valve core for placing the packing assembly.

[0006] Preferably, the packing assembly includes an elastic element and packing located at both ends of the elastic element; when the pneumatic actuator drives the valve core to close the valve body, the packing is located in the neck structure.

[0007] Preferably, the valve body also has a medium inlet and a medium outlet, which are coaxially arranged and can selectively communicate with the inner cavity of the valve body under the action of the valve core; the inner wall of the medium inlet has a first arc segment and a second arc segment, and the inner wall of the medium outlet has a third arc segment and a fourth arc segment; the curvatures of the four arc segments are R1, R2, R3 and R4, respectively, and R1=R2=R3=R4.

[0008] Preferably, the distance L1 between the first arc and the second arc is equivalent to the distance L2 between the third arc and the fourth arc, and the lengths of L1 and L2 are equivalent to the inner diameter D1 of the valve seat.

[0009] Preferably, the ports of the medium inlet and the medium outlet are formed with tapered welding end faces for welding and fixing to the pipeline.

[0010] Preferably, the output end of the valve core is made of an elastic material; a sealing ring is also provided on the outer periphery of the protrusion.

[0011] Preferably, the piston cylinder is provided with an air port for connecting to an air source.

[0012] Preferably, the input end of the valve core is located inside the cylinder seat, and its input end is provided with a pointer that moves synchronously with it. A stroke scale is fixed on the cylinder seat; the position of the pointer on the stroke scale indicates the opening degree of the regulating valve.

[0013] The advantages of the technical solution of this invention are mainly reflected in: 1. High safety: The valve body and pipeline are connected by welding, which reduces the risk of external leakage of the medium, making it particularly suitable for applications involving flammable, explosive, and toxic media.

[0014] 2. Easy maintenance: The top-mounted structure design allows the valve core and valve seat to be removed from the top after the valve cover is removed, without the need to disassemble the cold box and valve body. It is especially suitable for cryogenic applications such as ships where space is limited and the medium is flammable, explosive or toxic.

[0015] 3. Excellent sealing performance: The actuator with spring and pneumatic piston structure can provide higher thrust for valve sealing; at the same time, the Mark series packing system is used, which has reliable performance.

[0016] 4. High flow capacity: Optimized valve body flow channel design and uniform valve body flow channel cross-section can improve valve flow capacity and reduce turbulence. Attached Figure Description

[0017] Figure 1 Cross-sectional view of a preferred embodiment of the present invention; Figure 2 This invention Figure 1 Enlarged view of part A in the middle. Detailed Implementation

[0018] The objectives, advantages, and features of this invention will be illustrated and explained through the following non-limiting description of preferred embodiments. These embodiments are merely typical examples of applying the technical solutions of this invention, and all technical solutions formed by equivalent substitutions or equivalent transformations fall within the scope of protection claimed by this invention.

[0019] In the description of the solution, it should be noted that the terms "center," "upper," "lower," "left," "right," "front," "rear," "vertical," "horizontal," "inner," and "outer," etc., indicating the orientation or positional relationship, are based on the orientation or positional relationship shown in the accompanying drawings and are only for the convenience and simplification of 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, and therefore should not be construed as a limitation of the present invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance. Also, in the description of the solution, with the operator as a reference, the direction closer to the operator is the proximal end, and the direction farther from the operator is the distal end.

[0020] This invention discloses a control valve with high flow capacity applicable to cryogenic conditions (such as liquefied natural gas LNG, air separation units, etc.) to solve special problems under such conditions, such as sealing failure caused by thermal expansion and contraction, leakage risk of traditional flange connections, and maintenance difficulties in confined spaces.

[0021] A control valve for cryogenic applications includes, for example: Figure 1 The diagram shows a pneumatic actuator 1 and a valve body 2, with the cylinder seat 11 of the pneumatic actuator 1 connected to the valve cover 201 of the valve body 2 via a locking plate 3. The pneumatic actuator 1 includes at least a spring 101 and a pneumatic piston 102 disposed within a piston cylinder 10, and a connecting rod 111 disposed within the cylinder seat 11. Furthermore, the piston cylinder 10 is provided with an air port 100 for connecting to an air source. When gas is input into the air port 100 from the air source, a pressure difference is created within the piston cylinder 10, thereby causing the pneumatic piston 102 to move towards the spring 101, opening the internal passage of the valve body 2, allowing liquid to flow within the valve body 2, and controlling the liquid flow rate.

[0022] Traditional control valves mostly use high-thrust pneumatic piston actuators with internal return springs for the drive mechanism. This invention employs an actuator with a spring and a pneumatic piston structure, providing higher thrust for valve sealing. Furthermore, compared to traditional diaphragm actuators, the piston structure has higher rigidity, overcoming the significant unbalanced forces caused by changes in medium viscosity and high pressure differentials under cryogenic conditions, ensuring the valve achieves a tight leak-proof rating during emergency shut-off.

[0023] Furthermore, the output end of the connecting rod 111 is coaxially and fixedly connected to the valve core 202 disposed within the valve body 2, and the valve core 202 is driven to move relative to the valve seat 203 disposed within the valve body 2 via the pneumatic actuator 1. To avoid wear caused by hard contact between the valve core 202 and the valve seat 203, some embodiments of the present invention use an elastic material including silicone or similar materials for the output end of the valve core 202. Further, for example... Figure 1 As shown, the input end of the valve core 202 is located inside the cylinder seat 11, and its input end is provided with a pointer 12 that moves synchronously with it. A stroke scale 121 is fixed on the cylinder seat 11. The movement position of the pointer 12 on the stroke scale 121 indicates the opening degree of the regulating valve.

[0024] like Figure 1 As shown, the valve body 2 includes a welded valve body 21 and a cold box 22. The valve body 21 has a medium inlet 211 and a medium outlet 212, which are coaxially arranged and selectively communicate with the inner cavity 210 of the valve body under the action of the valve core 202. Furthermore, the ports of the medium inlet 211 and the medium outlet 212 form tapered welding end faces 2100 for welding and fixing to pipelines. In this invention, by providing tapered welding end faces on the medium inlet 211 and the medium outlet 212 and using butt welding to connect with process pipelines, the risk of medium leakage caused by bolt loosening in traditional flange connections under cryogenic alternating temperatures is completely eliminated. Simultaneously, the valve body and the cold box wall panel adopt a fully welded integrated sealing design, ensuring that the vacuum or insulation material inside the cold box is not invaded by external moisture; reducing a risk point of medium leakage, making it particularly suitable for applications involving flammable, explosive, or toxic media.

[0025] The valve cover 201 is located near the end of the cold box 22, and the input end of the valve core 202 passes through the valve cover 201 and the cylinder seat 11. The valve cover 201 is cross-shaped, with its two ends extending towards the cylinder seat 11 and the cold box 22 respectively to form a neck structure 2011. The bottom of the neck structure 2011, located within the cold box 22, has a step extending towards the valve core 202 for placing the packing assembly 221. The neck structure 2011 increases the packing area, ensuring that the working temperature of the packing area is much higher than the freezing point or solidification point of the cryogenic fluid. This effectively prevents the packing material from excessively shrinking, hardening, or losing elasticity due to low temperatures, and prevents the medium from freezing or crystallizing at the packing, thereby maintaining the dynamic sealing performance of the shaft seal system. It also ensures the smooth movement of the valve core, preventing additional friction or jamming. Simultaneously, when the cryogenic liquid medium enters the valve body, due to its own saturated vapor pressure, a portion of the medium will vaporize in the lower region of the extended neck due to heat conduction, forming a gas phase. The tiny gap created by the up-and-down movement of the valve core makes it difficult for this portion of the gaseous medium to undergo large-scale convection or be rapidly carried away, thus forming a stable gas column within the valve cover neck. This gas column effect successfully establishes a smooth yet steep temperature gradient between the extremely low temperature bottom of the valve body and the relatively high temperature top of the stuffing box.

[0026] A packing assembly 221 is centrally symmetrically arranged within the valve cover 201. Further, the packing assembly 221 includes an elastic element and packing located at both ends of the elastic element. When the pneumatic actuator 1 drives the valve core 202 to close the valve body 21, the packing is located within the neck structure 2011. Preferably, the packing assembly 221 uses the Mark series packing system to provide reliability. Further, the Mark series environmentally friendly packing system consists of multiple sets of V-shaped PTFE (polytetrafluoroethylene) or graphite rings, equipped with a disc spring assembly for compensation. When the packing shrinks due to low temperature or wear, the disc spring continuously provides compensating pressure, ensuring continuous dynamic sealing performance.

[0027] Specifically, the elastic element can be made of components with elastic functions, including disc springs disclosed in the prior art. Compared with the structure in the prior art where the packing is placed at one end of the elastic element, the present invention has packing at both ends of the elastic element. By constructing a symmetrical, self-compensating force system, it solves the problems of uneven force distribution and poor compensation effect in the traditional unidirectional pressing method, thereby achieving a longer sealing life, more stable valve performance, and higher operational reliability. Specifically, during operation, the elastic element acts on both sets of packing simultaneously, making the radial force in the middle of the packing chamber in the valve cover 201 the largest, and evenly transmitted to both sides of the valve core 202 and the inner wall of the packing chamber, forming a more reasonable and uniform pressure distribution. This effectively avoids the "conical" pressure distribution with high pressure at one end and low pressure at the other end in the prior art, thereby ensuring effective sealing along the entire sealing length. This effectively avoids the "shaft gripping" phenomenon and abnormal frictional heating caused by local overtightening. It reduces the frictional force of the valve core movement, improves the response sensitivity and control accuracy of the regulating valve; at the same time, uniform wear also extends the service life of the packing and the valve core itself. 2. Regardless of whether the upper or lower packing is worn, the pre-compressed disc spring can simultaneously and automatically expand in both directions, continuously replenishing the clamping force on the worn packing. This compensation is dynamic and bidirectional synchronous, more effectively maintaining the sealing force of the entire stuffing box and significantly extending the maintenance cycle. 3. Under conditions of temperature cycling, pressure fluctuations, or vibration, the relative position of the valve core and packing may change slightly. The bidirectional spring-loaded structure acts like a "buffer" and "constant force device," absorbing some vibration and maintaining a relatively constant sealing force, thus improving the sealing reliability of the system under dynamic conditions.

[0028] The inner cavity 220 of the cold box 22 communicates with the inner cavity 210 of the valve body 21 to accommodate the valve core 202. That is, the output end of the valve core 202 can enter the inner cavity 210 of the valve body through the inner cavity 220 of the cold box, and is sealed and fixed by the valve cover 201 and the locking plate 3. This design meets the requirements of limited space in cold boxes in ships or compact factories, namely through a top-mounted quick-disassembly structure: when the valve needs maintenance, there is no need to damage the cold box insulation layer or cut pipes; only the valve cover needs to be removed to lift the valve core, valve seat, and internal components out from the top of the valve as a whole, making the operation simple and quick.

[0029] To complement the aforementioned top-mounted quick-disassembly structure and improve stability during use, this invention preferably includes an integrally formed protrusion 2021 on the main body of the valve core 202 near its output end, with the outer diameter of the protrusion 2021 being approximately equal to the inner diameter of the valve body cavity 210. Furthermore, the outer periphery of the protrusion 2021 is also provided with... Figure 2 The sealing ring shown is 2022.

[0030] Furthermore, such as Figures 1 to 2 As shown, the outer diameter of the output end of the valve core 202 is approximately equal to the inner diameter D1 of the valve seat 203, but smaller than the diameter D2 of the inner cavity 210 of the valve body; the diameter D2 of the inner cavity 210 of the valve body is smaller than the diameter D3 of the inner cavity 210 of the cold box. The protrusion 2021 not only serves as a guide for the valve core and has a sealing ring on its outer periphery, but also provides a better sealing effect.

[0031] Furthermore, such as Figure 1 The inner wall of the medium inlet 211 is formed with a first arc segment and a second arc segment, and the inner wall of the medium outlet 212 is formed with a third arc segment and a fourth arc segment. The curvatures of the four arc segments are R1, R2, R3, and R4, respectively, and R1=R2=R3=R4. Furthermore, the distance L1 between the first arc and the second arc is equivalent to the distance L2 between the third arc and the fourth arc, and the lengths of L1 and L2 are equivalent to the inner diameter D1 of the valve seat 203. To meet the requirement of high flow capacity, the flow channel curvature of the valve body cavity is optimized through CFD (Computational Fluid Dynamics) simulation, R1=R2=R3=R4, constructing a uniform flow channel cross-section. This not only reduces the flow resistance coefficient and improves the flow capacity of the valve, but also effectively suppresses flashing and cavitation phenomena caused by pressure drops when the medium flows through the narrowing section, thereby extending the service life of the valve body and reducing fluid-induced vibration and noise.

[0032] This invention has many other embodiments, and all technical solutions formed by equivalent transformation or equivalent transformation fall within the protection scope of this invention.

Claims

1. A regulating valve for cryogenic service, characterized by: The valve body (2) includes a welded fixed valve body (21) and a cold box (22); the proximal end of the cold box (22) is provided with the valve cover (201); the valve cover (201) is centrally symmetrically provided with a packing assembly (221); the cold box inner cavity (220) of the cold box (22) is in communication with the valve body inner cavity (210) of the valve body (21) to accommodate the valve core (202); the main body near the output end of the valve core (202) is integrally provided with a protrusion (2021), and the outer diameter of the protrusion (2021) is equivalent to the inner diameter of the valve body inner cavity (210); the outer diameter of the output end of the valve core (202) is equivalent to the inner diameter D1 of the valve seat (203) and is smaller than the diameter D2 of the valve body inner cavity (210); the diameter D2 of the valve body inner cavity (210) is smaller than the diameter D3 of the cold box inner cavity (210).

2. The regulating valve for use in cryogenic conditions according to claim 1, characterized in that: The input end of the valve core (202) penetrates the valve cover (201) and the cylinder seat (11); the valve cover (201) is cross-shaped, and the main body of the valve cover (201) extends to the cylinder seat (11) and the cold box (22) at both ends to form a neck structure (2011), wherein the bottom of the neck structure (2011) located in the cold box (22) forms a step extending to the direction of the valve core (202) to place the packing assembly (221).

3. The regulating valve for cryogenic service of claim 2, wherein: The packing assembly (221) includes an elastic member and packing located at both ends of the elastic member; when the valve core (202) is driven by the pneumatic actuator (1) to close the valve body (21), the packing is located in the neck structure (2011).

4. The regulating valve for cryogenic service of claim 1, wherein: The valve body (21) is also provided with a medium inlet (211) and a medium outlet (212), which are coaxially arranged and selectively communicated with the valve body inner cavity (210) under the action of the valve core (202); the inner wall of the medium inlet (211) is formed with a first arc segment and a second arc segment, and the inner wall of the medium outlet (212) is formed with a third arc segment and a fourth arc segment; the curvatures of the four arc segments are R1, R2, R3 and R4, and R1=R2=R3=R4.

5. The regulating valve for cryogenic service of claim 4, wherein: The distance L1 between the first arc and the second arc is equivalent to the distance L2 between the third arc and the fourth arc, and the lengths of L1 and L2 are equivalent to the inner diameter D1 of the valve seat (203).

6. The regulating valve for cryogenic service of claim 4, wherein: The ports of the medium inlet (211) and the medium outlet (212) are formed with tapered welding end faces (2100) so as to be welded and fixed with pipes.

7. The regulating valve for cryogenic service of claim 1, wherein: The output end of the valve core (202) is made of elastic material; the outer periphery of the protruding block (2021) is further provided with a sealing ring (2022).

8. The regulating valve for cryogenic service of claim 1, wherein: The piston cylinder (10) is provided with a gas hole (100) for connecting a gas source.

9. The regulating valve for cryogenic service of claim 1, wherein: The input end of the valve core (202) is located in the cylinder seat (11), and the input end is provided with a pointer (12) moving synchronously therewith; the cylinder seat (11) is fixed with a stroke scale (121); the moving position of the pointer (12) on the stroke scale (121) indicates the opening degree of the regulating valve.

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