Valve rod assembly and top-mounted low-temperature floating ball valve adopting same

Abstract

The utility model relates to a valve component, in particular to a valve rod assembly and a top-mounted low-temperature floating ball valve with the valve rod assembly. The valve rod assembly comprises a lengthened valve rod, an upper valve body and a stuffing box formed between the lengthened valve rod and the upper valve body. A packing gland and a packing backing ring with a step part are arranged in the packing box to form an upper and lower double-cavity structure; two rectangular packing and a middle V-shaped combined packing are arranged in the packing cavity, and are axially pre-tightened through the gland to form packing seal; an elastomer sealing piece is arranged in the sealing cavity, and metal sealing of an elastomer is achieved. The valve rod is lengthened, so that heat of a low-temperature medium is fully dissipated when being transmitted to the filler, the filler and the elastomer sealing piece are prevented from embrittling and losing elasticity due to low temperature, elastomer-to-metal sealing is formed through the elastomer sealing piece, and filler-to-metal sealing is formed through cooperation of the filler gland, the rectangular filler and the V-shaped combined filler. Double sealing is formed, and the sealing reliability and the product quality of equipment under the low-temperature working condition can be improved.

Description

Technical Field

[0001] The utility model relates to valve components, and particularly to a valve stem assembly and a top-mounted cryogenic floating ball valve adopting the assembly. Background Art

[0002] With the rapid development of the petroleum, chemical and gas industries, especially the wide application of liquefied natural gas as a new type of energy, the demand for cryogenic valves is increasing. The main characteristics of a floating ball valve are its compact structure, reliable sealing, simple structure, convenient maintenance, the sealing surface and the spherical surface are often in a closed state, not easily eroded by the medium, easy to operate and maintain, and suitable for the transportation of various cryogenic media. The valve sealing performance is directly related to the safety and reliability of the equipment. In traditional floating ball valves, the valve stem structure cannot be well adapted to cryogenic working conditions and is prone to leakage from the valve stem. Therefore, it is necessary to have a valve stem assembly suitable for cryogenic working conditions and a floating ball valve adopting the assembly. Summary of the Utility Model

[0003] The purpose of the utility model is to provide a valve stem assembly and a top-mounted cryogenic floating ball valve adopting the assembly, which can solve the deficiencies existing in the prior art.

[0004] To achieve these purposes, the present application provides the following technical solutions: A valve stem assembly includes an upper valve body, a valve stem, and a stuffing box formed between the upper valve body and the valve stem. The valve stem is lengthened to increase the distance between the stuffing box and the valve cavity of the valve. The stuffing box includes a stuffing gland and a stuffing spacer ring. A stuffing cavity is formed between the upper end of the stuffing spacer ring and the stuffing gland. Two rectangular packings and at least one set of V-shaped combined packings are arranged in the stuffing cavity, and the V-shaped combined packing is located between the two rectangular packings; a sealing cavity is formed between the lower end of the stuffing spacer ring and the upper valve body, and at least one elastomeric seal is arranged in the sealing cavity; the stuffing spacer ring forms a stepped portion, and the axial pre-tightening force applied by the stuffing gland to the stuffing is at least partially transmitted to the inner wall of the upper valve body through the stepped portion.

[0005] As a preferred embodiment, at least one annular step surface and / or wedge surface is formed on the inner wall of the upper valve body corresponding to the stepped portion, and the stepped portion abuts against the step surface or wedge surface under the action of the axial pre-tightening force of the stuffing gland to prevent the axial pre-tightening force of the stuffing gland from continuing to be transmitted to the elastomeric seal.

[0006] As a preferred embodiment, a steam chamber is formed by the gap between the inner wall of the upper valve body and the valve stem. An air pressure balance hole is formed on the upper valve body. The air pressure balance hole includes a pressure relief hole A and a pressure relief hole B that communicate with each other; the pressure relief hole A is opened on the side wall of the upper valve stem and communicates with the steam chamber; the pressure relief hole B is opened along the axial direction of the valve stem and is used to communicate with the flow channel of the valve.

[0007] As a preferred embodiment, a one-way seal is provided at the end of the pressure relief hole B. The one-way seal closes under the action of valve closing or channel pressure to prevent the channel medium from entering the valve cavity, and opens to relieve pressure when the valve cavity or the steam chamber is over-pressured.

[0008] As a preferred embodiment, it further includes a packing spacer ring. The packing spacer ring is arranged in the packing cavity. At least two groups of V-shaped combined packings are arranged in the packing cavity, and the packing spacer ring is arranged between the two groups of V-shaped combined packings.

[0009] As a preferred embodiment, the V-shaped combined packing is composed of a plurality of stacked V-shaped packing rings. The V-shaped structures of the V-shaped packing rings in each V-shaped combined packing face the same direction, and each group of V-shaped combined packings includes 2 to 6 V-shaped packing rings.

[0010] As a preferred embodiment, the elastomeric seal is a lip seal ring, and retaining rings are arranged on both sides of the lip seal ring.

[0011] As a preferred embodiment, a drip tray is further provided on the upper valve body to prevent condensed water from flowing into the valve body insulation layer.

[0012] As a preferred embodiment, the packing gland is connected to the valve body by studs. A disc spring is abutted between the packing gland and the stud nut, and the disc spring provides a continuous elastic pre-tightening force.

[0013] The present application also provides a top-mounted cryogenic floating ball valve, including the above-mentioned valve stem assembly.

[0014] Advantages of the present application compared with the prior art:

[0015] In the present application, by lengthening the valve stem, the cold quantity of the cryogenic medium is fully dissipated when it is transmitted to the packing, avoiding the embrittlement and loss of elasticity of the packing and the elastomeric seal due to low temperature. Through the step design of the packing spacer ring, a packing cavity and a sealing cavity are formed. In the sealing cavity, an elastomeric seal is formed between the elastomer and the metal through the elastomeric seal, and in the packing cavity, a packing-to-metal seal is formed by the cooperation of the packing gland, the rectangular packing and the V-shaped combined packing, forming a double sealing effect, enhancing the sealing reliability and product quality of the equipment under cryogenic conditions;

[0016] In the present application, the axial pre-tightening force of the packing gland is at least partially transmitted to the inner wall of the upper valve body through the stepped portion, rather than directly acting on the elastomeric seal in the sealing cavity. Therefore, on the basis of satisfying the double sealing effect, the present application helps to reduce the situation that the elastomeric seal is prone to overload failure caused by the packing pre-tightening force, or the situation that the packing sealing effect decreases due to reducing the pre-tightening force on the packing and reducing the pressure applied to the elastomeric seal, improving the sealing stability and service life of the equipment under cryogenic conditions. Description of the Drawings

[0017] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0018] Figure 1 It is a schematic cross-sectional structure diagram of one embodiment of the valve stem assembly of the present invention;

[0019] Figure 2 For Figure 1 The enlarged view at A in

[0020] Figure 3 It is a side view of one embodiment of the valve stem assembly of the present invention;

[0021] Figure 4 It is a schematic structural diagram of one embodiment of the top-mounted cryogenic floating ball valve of the present invention;

[0022] Markings in the figure: 1 - upper valve body; 2 - valve stem; 3 - stuffing box; 4 - valve body; 5 - valve seat assembly; 6 - valve ball; 7 - left body; 11 - drip tray; 12 - anti-static component; 21 - steam chamber; 22 - air pressure balance hole; 221 - pressure relief hole A; 222 - pressure relief hole B; 31 - packing gland; 32 - packing spacer ring; 321 - step portion; 33 - elastomeric seal; 34 - rectangular packing; 35 - V-shaped combined packing; 36 - packing spacer ring; 37 - retaining ring; 38 - disc spring; 41 - valve cavity. Specific embodiments

[0023] The following will clearly and completely describe the technical solutions of the present invention in combination with the embodiments. Obviously, the described embodiments are some embodiments of the present invention, rather than all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts belong to the scope of protection of the present invention.

[0024] Please refer to Figures 1 to 4, this embodiment provides a valve stem assembly, including an upper valve body 1, a valve stem 2, and a stuffing box 3 formed between the upper valve body 1 and the valve stem 2. The valve stem 2 is lengthened, so that the height of the stuffing box 3 is lifted; the stuffing box 3 includes a stuffing gland 31 and a stuffing spacer ring 32. A stuffing chamber is formed between the upper end surface of the stuffing spacer ring 32 and the stuffing gland 31. The stuffing chamber includes two rectangular packings 34 and at least one set of V-shaped combined packings 35 arranged between the two rectangular packings 34. An axial pre-tightening force is applied to the stuffing through the stuffing gland 31, so that the stuffing is closely attached to the valve stem 2 and the inner wall of the stuffing box to form a stuffing seal. Among them, the V-shaped combined packing 35 mainly plays a sealing role, and the rectangular packing 34 is mainly used to protect the V-shaped combined packing 35 to avoid direct contact with the axial metal parts. The regular shape of the rectangular packing 34 helps to reduce the situation that the V-shaped combined packing 35 is extruded from the stuffing chamber due to poor pre-tightening of the stuffing gland 31.

[0025] A sealing chamber is formed between the lower end surface of the stuffing spacer ring 32 and the upper valve body 1. An elastomeric seal 33, preferably a lip seal, is provided in the sealing chamber to form an elastomer-to-metal seal on the surface of the valve stem 2; the stuffing spacer ring 32 also has a stepped portion 321, and the stepped portion 321 abuts against at least a part of the inner wall of the upper valve body 1 in the axial direction of the valve stem 2. The axial pre-tightening force applied by the stuffing gland 31 is transmitted to the stepped portion 321 through the V-shaped combined packing 35 and then transmitted to the inner wall of the upper valve body 1 to reduce the transmission of the axial pre-tightening force to the elastomeric seal 33 in the sealing chamber; Retaining rings 37 are also provided on both sides of the elastomeric seal 33 in the sealing chamber to prevent the elastomeric seal 33 from being extruded out of the sealing chamber under pressure.

[0026] It can be understood that the stuffing can usually withstand high pressures to form an effective stuffing seal, while the requirements for the axial pre-tightening force of the elastomeric seal 33, such as a lip seal, are different from those of the stuffing. Excessive pre-tightening force is likely to cause the lip seal to wear out faster, while reducing the pre-tightening force of the stuffing gland 31 is likely to affect the effect of the stuffing seal; by providing the stepped portion 321, on the basis of meeting the double-sealing effect, it helps to reduce the situation that the elastomeric seal 33 is prone to overload failure caused by the stuffing pre-tightening force, or reduces the situation that the stuffing seal effect decreases due to the pressure applied to the elastomeric seal by reducing the pre-tightening force of the stuffing, and improves the stability and service life of the equipment under low-temperature conditions.

[0027] Please refer to Figure 2, in the above stuffing box, the V-shaped combined packing 35 that mainly plays a sealing role is composed of a plurality of stacked V-shaped packing rings. The V-shaped structure between the V-shaped packing rings enables it to better adaptively and closely fit the valve stem 2 and the inner wall of the upper valve body 1 when subjected to the axial pre-tightening force of the packing gland 31. Compared with the simple rectangular packing 34, at the same time, the cooperation of multiple V-shaped packing rings makes it easier for the V-shaped combined packing 35 to supplement the wear of the packing due to long-term use, continue to maintain close contact with the valve stem 2 and the inner wall of the stuffing box, and extend the service life of the seal. In addition, compared with the rectangular packing 34, when the medium passes through the V-shaped packing layer, it needs to pass through multiple tortuous channels, thereby effectively reducing the possibility of leakage and improving the reliability of the seal.

[0028] It can be understood that in this application, by lengthening the valve stem 2, the cold quantity of the low-temperature medium is fully dissipated when it is transmitted to the stuffing, avoiding the brittleness and loss of elasticity of the packing and the elastomeric seal 33 due to low temperature. Through the step design of the packing spacer ring 32, a stuffing box and a sealing cavity are formed. In the sealing cavity, an elastomeric-to-metal seal is formed through the elastomeric seal 33. In the stuffing box, a packing-to-metal seal is formed through the cooperation of the packing gland 31 with the rectangular packing 34 and the V-shaped combined packing 35. The axial pre-tightening force of the packing gland 31 is transmitted to the step portion 321 through the inclined plane deformation component force of the V-shaped combined packing 35, rather than directly acting on the elastomeric seal 33 in the sealing cavity, which helps to improve the sealing stability and service life of the equipment under low-temperature working conditions.

[0029] As a preferred embodiment, please refer to Figure 2 , an abutting portion is formed on the inner wall of the upper valve body 1 corresponding to the step portion 321, for example, an annular step surface and / or a wedge surface is formed. The abutting portion is smoothly transitioned with the inner wall of the sealing cavity. The step portion 321 abuts against the abutting portion under the action of the axial pre-tightening force of the packing gland, preventing the axial pre-tightening force of the packing gland from continuing to be transmitted to the elastomeric seal, thereby reducing the influence of the axial pre-tightening force of the packing gland on the elastomeric seal.

[0030] As a preferred embodiment, please refer to Figure 2 , a packing spacer ring 36 is arranged in the stuffing box. The stuffing box includes at least two groups of V-shaped combined packings 35. The packing spacer ring 36 is arranged between the two groups of V-shaped combined packings 35. Exemplarily, each group of V-shaped combined packings 35 can include four stacked V-shaped packing rings, and the V-shaped structures in each V-shaped packing ring have the same orientation. In this structure, V-shaped combined packings 35 are arranged on both sides of the packing spacer ring 36. When one group of V-shaped combined packings 35 is damaged and fails, the other group can still play a sealing role.

[0031] As a preferred embodiment, please refer to Figure 4, a gap between the inner wall of the upper valve body 1 and the valve stem 2 forms a steam chamber 21. When assembled with the valve body 4, the steam chamber 21 can communicate with the valve cavity 41 of the valve; further, an air pressure balance hole 22 is formed at the end of the valve stem 2 away from the stuffing box 3. The air pressure balance hole 22 includes a pressure relief hole A221 and a pressure relief hole B222 that communicate with each other; wherein, the pressure relief hole A221 is opened on the side wall of the valve stem 2 and communicates with the steam chamber 21; the pressure relief hole B222 is opened along the axial direction of the valve stem 2 and extends to the part where the valve stem 2 cooperates with the valve ball 6. When assembled with the valve body 4, the pressure relief hole B222 forms a conduction with the flow channel of the valve; thus, when the low-temperature liquid in the valve cavity 41 vaporizes due to temperature fluctuations, resulting in an abnormal increase in the pressure in the valve cavity 41, the pressure in the valve cavity 41 and the steam chamber 21 can be released into the flow channel of the valve. Further still, a one-way seal (not shown in the figure) can be provided at the end of the pressure relief hole B222, such as a spring-loaded conical valve core, which closes when the valve is closed or under the action of the pressure of the medium in the flow channel, preventing the medium in the valve flow channel from directly entering the valve cavity 41, and opening when a large air pressure is generated in the valve cavity 41 or the steam chamber 21, and discharging the pressure to the flow channel of the valve due to the one-way seal.

[0032] As a preferred embodiment, please refer to Figures 2 to 3 , the packing gland 31 is connected to the valve body 4 by studs, and a disc spring 38 is abutted between the packing gland 31 and the nut of the stud. Among them, the disc spring 38 compensates for the gap caused by packing wear and low-temperature shrinkage by providing a continuous elastic pre-tightening force, ensuring the stability of the axial pre-tightening force of the packing gland 31 on the sealing structure and improving the sealing reliability. A drip tray 11 is also provided on the upper valve body 1, and the drip tray 11 is used to prevent condensed water from flowing into the valve body insulation layer.

[0033] Embodiment 2, please refer to Figure 4 , an upper-mounted cryogenic floating ball valve includes a valve body 4, a valve seat assembly 5 arranged in its inner cavity, the valve stem assembly described in Embodiment 1, a valve ball 6 cooperating with the valve seat assembly 5, and a left body 7 cooperating with the valve body 4 to form a valve cavity 41; the valve stem assembly and the valve stem 2 can be directly inserted into the valve body 4 from above, and the upper valve body 1 and the valve body 4 are fixed by studs, which is convenient for disassembly and maintenance; wherein, an anti-static component 12 can also be provided between the valve stem and the valve body to eliminate the static charges generated by friction during the opening and closing of the valve stem, and avoid igniting flammable and explosive media (such as LNG) due to static sparks. Since the floating ball valve in this embodiment adopts all the technical solutions of the above Embodiment 1, the upper-mounted cryogenic floating ball valve in this embodiment has all the technical effects brought by the technical solutions of the above Embodiment 1, so it will not be elaborated here.

[0034] The above are only the preferred embodiments of the present utility model, and are not intended to limit the present utility model. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principle of the present utility model shall be included within the protection scope of the present utility model.

Claims

1. A valve stem assembly, comprising an upper valve body, a valve stem and a stuffing box, characterized in that: The valve stem is lengthened to increase the distance between the stuffing box and the valve cavity. The stuffing box includes a stuffing gland and a stuffing ring. A stuffing cavity is formed between the upper end of the stuffing ring and the stuffing gland. Two rectangular packings and at least one group of V-shaped combined packings are arranged in the stuffing cavity. The V-shaped combined packing is located between the two rectangular packings. A sealing cavity is formed between the lower end of the stuffing ring and the upper valve body. At least one elastomeric seal is arranged in the sealing cavity. The stuffing ring forms a step portion. The axial preload force applied by the stuffing gland to the packing is at least partially transmitted to the inner wall of the upper valve body through the step portion.

2. The valve stem assembly according to claim 1, characterized in that: The inner wall of the upper valve body corresponds to the step portion to form at least an annular step surface and / or a wedge surface. The step portion abuts against the step surface or the wedge surface under the action of the axial preload force of the packing gland, preventing the axial preload force of the packing gland from continuing to be transmitted to the elastomeric seal.

3. The valve stem assembly according to claim 1, characterized in that: A steam chamber is formed in the gap between the inner wall of the upper valve body and the valve stem. An air pressure balance hole is formed on the upper valve body. The air pressure balance hole includes a pressure relief hole A and a pressure relief hole B which are connected to each other. The pressure relief hole A is opened on the side wall of the upper valve stem and connected to the steam chamber. The pressure relief hole B is opened along the axial direction of the valve stem and is used to communicate with the flow channel of the valve.

4. The valve stem assembly according to claim 3, characterized in that: A one-way seal is provided at the end of the pressure relief hole B, which is closed when the valve is closed or the flow medium pressure is applied, preventing the flow medium from entering the air pressure balance hole, and opens to relieve pressure into the flow channel when the valve cavity or steam chamber is over-pressured.

5. The valve stem assembly according to claim 1, characterized in that: A packing spacer ring is arranged in the packing cavity, at least two groups of V-shaped combined packings are arranged in the packing cavity, and the packing spacer ring is arranged between the two groups of V-shaped combined packings.

6. The valve stem assembly according to claim 1, characterized in that The V-shaped combined packing is composed of a plurality of stacked V-shaped packing rings, the V-shaped structures of the V-shaped packing rings in each V-shaped combined packing are oriented in the same direction, and each group of V-shaped combined packing includes 2 to 6 V-shaped packing rings.

7. The valve stem assembly according to claim 1, characterized in that: The elastic body seal is a lip seal ring, and retaining rings are arranged on both sides of the lip seal ring.

8. The valve stem assembly according to claim 1, characterized in that The upper valve body is also provided with a drip tray for preventing condensed water from flowing into the valve body insulation layer.

9. The valve stem assembly according to claim 1, characterized in that: The packing gland is connected to the valve body via a stud, and a butterfly spring is abutted between the packing gland and the stud nut to provide continuous elastic pre-tightening force.

10. A top-entry cryogenic floating ball valve, characterized in that: Comprising the valve stem assembly according to any one of claims 1 to 9.

Images