Cascadable controllable fluid control valve and valve internals for a fluid control valve

Abstract

A fluid control valve having a body, a seat ring, a valve cage adjacent to the seat ring, a first valve plug assembly disposed within the valve cage, and a second valve plug assembly disposed within an axial bore of the first valve plug assembly. The first valve plug assembly has: a radial bore in fluid communication with the axial bore; and a first valve plug including the axial bore and a throttling port in fluid communication with the axial bore. The first valve plug assembly is movable between a closed position in engagement with the seat ring and an open position separated from the seat ring. The second valve plug assembly has a second valve plug that is movable between a closed position in engagement with the first valve plug and an open position separated from the first valve plug.

Description

Technical Field

[0001] Broadly speaking, the present disclosure relates to fluid control valves, and more particularly, to a cascaded controllable internal component assembly for a fluid control valve. Background Art

[0002] In certain applications, a fluid control valve with a high flow control range may be required. For example, a fluid control valve may be needed in situations where the pressure drop is large at low flow conditions and small at high flow conditions. Due to the large port size of larger fluid control valves, traditional fluid control valves cannot meet these requirements.

[0003] One possible way to address these specific applications is to use a large fluid control valve with a valve cage having features. The valve cages in these fluid control valves are characterized by multiple stages at low stroke to resist high pressure drops at low flow. In view of this, the fluid control valve must be larger than a typical fluid control valve to provide a larger flow control capacity. However, larger fluid control valves generally have larger port sizes, so the control valve cannot control low or very low flows.

[0004] Another way to address these applications is to use two separate valves. By using two valves, a small valve can be used to control low flows with high pressure drops, and a large valve can be used to control high flow rates with low pressure drops. However, the use of two separate valves increases the cost and space requirements for a particular installation. Summary of the Invention

[0005] According to an exemplary aspect of the present invention, a fluid control valve includes a body, a seat ring, a valve cage disposed adjacent to the seat ring, a first valve plug assembly disposed within the valve cage, and a second valve plug assembly disposed within the first valve plug assembly. The body defines an inlet, an outlet, and a passage between the inlet and the outlet, and the seat ring is disposed in the passage. The valve cage is disposed between the inlet and the outlet and includes a plurality of radial openings. The first valve plug assembly includes a plurality of radial holes and a first valve plug having an axial hole in fluid communication with the radial holes and a throttling port in fluid communication with the axial hole. The first valve plug is movable between a closed position and an open position, wherein in the closed position, the first valve plug engages the seat ring, and in the open position, the first valve plug is separated from the seat ring. The second valve plug assembly is disposed within the axial hole of the first valve plug assembly and includes a second valve plug that is movable within the first valve plug assembly between a closed position and an open position, wherein in the closed position, the second valve plug engages the first valve plug, and in the open position, the second valve plug is separated from the first valve plug.

[0006] Further according to any one or more of the foregoing exemplary aspects of the present invention, the fluid control valve may further include any one or more of the following preferred forms in any combination.

[0007] In a preferred form, the plurality of radial holes are formed through the first valve plug.

[0008] In another preferred form, the first valve plug assembly includes a retainer and a spring, the retainer being fixed to the first valve plug, the spring being disposed within the retainer and between the first valve plug and the second valve plug, wherein the spring biases the second valve plug away from the first valve plug, and the plurality of radial holes are formed through the retainer.

[0009] In another preferred form, the spring is isolated from the process fluid.

[0010] In another preferred form, the first valve plug includes a tapered end.

[0011] In another preferred form, the second valve plug assembly includes a valve stem connecting the second valve plug to an actuator.

[0012] In another preferred form, the second valve plug includes one or more holes therethrough to pressure balance the second valve plug.

[0013] In another preferred form, the second valve plug includes: a first portion, a second portion, and a seat surface. The diameter of the first portion is greater than the diameter of the throttling port, the diameter of the second portion is less than the diameter of the throttling port, and the seat surface engages the first valve plug and the second valve plug in the closed position.

[0014] In another preferred form, the second valve plug includes: a conical portion extending from the second portion and a third portion extending from the conical portion, and the third portion has a generally cylindrical portion and a planar portion.

[0015] In another preferred form, the second valve plug includes a third portion extending from the second portion, and the third portion is generally cylindrical and includes one or more grooves.

[0016] In another preferred form, the first valve plug includes a plurality of concentric annular channels axially aligned around the throttling port, and the second valve plug includes a plurality of concentric annular protrusions configured to be received in corresponding channels.

[0017] In another preferred form, each channel has a width, wherein the width of each channel is less than the width of an adjacent channel closer to the throttling port, and the plurality of protrusions all have the same width.

[0018] According to another exemplary aspect of the present invention, an internal component assembly for a fluid control valve, the internal component assembly including: a seat ring, a valve cage disposed adjacent to the seat ring, a first valve plug assembly disposed within the valve cage, and a second valve plug assembly disposed within the first valve plug assembly. The valve cage is disposed between an inlet and an outlet of the fluid control valve and includes a plurality of radial openings. The first valve plug assembly includes a plurality of radial holes and a first valve plug having an axial hole in fluid communication with the radial holes and a throttling port in fluid communication with the axial hole. The first valve plug is movable between a closed position and an open position, wherein in the closed position, the first valve plug engages the seat ring, and in the open position, the first valve plug is separated from the seat ring. The second valve plug assembly is disposed within the axial hole of the first valve plug assembly and includes a second valve plug that is movable within the first valve plug assembly between a closed position and an open position, wherein in the closed position, the second valve plug engages the first valve plug, and in the open position, the second valve plug is separated from the first valve plug.

[0019] Further in accordance with any one or more of the foregoing exemplary aspects of the present invention, the trim assembly for a fluid control valve may also include any one or more of the following preferred forms in any combination of the preferred forms.

[0020] In one preferred form, the plurality of radial holes are formed through the first valve plug.

[0021] In another preferred form, the first valve plug assembly includes a retainer and a spring, the retainer being fixed to the first valve plug, the spring being disposed within the retainer and between the first valve plug and the second valve plug. The spring biases the second valve plug away from the first valve plug, and the plurality of radial holes are formed through the retainer.

[0022] In another preferred form, the spring is isolated from the process fluid.

[0023] In another preferred form, the second valve plug assembly includes a valve stem connecting the second valve plug to an actuator.

[0024] In another preferred form, the second valve plug includes one or more holes therethrough to pressure balance the second valve plug.

[0025] In another preferred form, the second valve plug includes: a first portion, a second portion, and a seat surface, the diameter of the first portion being greater than the diameter of the throttling port, the diameter of the second portion being less than the diameter of the throttling port, the seat surface engaging the first valve plug with the second valve plug in the closed position.

[0026] In another preferred form, the first valve plug includes a plurality of concentric annular channels axially aligned around the throttling port, each channel having a width. The width of each channel is less than the width of an adjacent channel closer to the throttling port. The second valve plug includes a plurality of concentric annular protrusions configured to be received in corresponding channels, each protrusion having the same width. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 is a side cross-sectional view of a fluid control valve having an exemplary cascade trim assembly;

[0028] Figure 2A is Figure 1 a partial enlarged view of the cascade trim assembly of;

[0029] Figure 2B is Figure 2A a partial enlarged view of a portion of the cascade trim assembly of;

[0030] Figure 3A Is Figure 1 A side cross-sectional view of a cascaded internal component assembly, where the first and second valve plug assemblies are in the closed position;

[0031] Figure 3B Is Figure 1 A side cross-sectional view of a cascaded internal component assembly, where the first valve plug assembly is in the closed position and the second valve plug assembly is in the fully open position;

[0032] Figure 3C Is Figure 1 A side cross-sectional view of a cascaded internal component assembly, where the first valve plug assembly is in the partially open position and the second valve plug assembly is in the fully open position;

[0033] Figure 3D Is Figure 1 A side cross-sectional view of a cascaded internal component assembly, where the first and second valve plug assemblies are in the open position;

[0034] Figure 4 Is Figure 1 An enlarged side view of a portion of an exemplary second valve plug of the second valve plug assembly of

[0035] Figure 5 Is another exemplary second valve plug that can be used in the second valve plug assembly of Figure 1 An enlarged side view of a portion of another exemplary second valve plug that can be used in the second valve plug assembly of

[0036] Figure 6 Is another exemplary second valve plug that can be used in the second valve plug assembly of Figure 1 An enlarged side view of a portion of another exemplary second valve plug that can be used in the second valve plug assembly of

[0037] Figure 7 Is a side cross-sectional view of a fluid control valve having another exemplary cascaded internal component assembly;

[0038] Figure 8 Is Figure 7 A partial enlarged view of a portion of the cascaded internal component assembly of ; and

[0039] Figure 9 Is a side cross-sectional view of a fluid control valve having another exemplary cascaded internal component assembly. Detailed Description

[0040] The exemplary fluid control valves and internal component assemblies described herein provide two cascaded controllable plugs that provide a fluid control valve with a high flow control range in a single, smaller, compact fluid control valve. A first larger plug and cage can control large fluid flows, and a second smaller plug can accurately control small fluid flows. Thus, since the second smaller plug requires a smaller port size, the fluid control valves and internal component assemblies described herein can provide more accurate control for smaller fluid flows.

[0041] See Figure 1 、 2A and Figure 2B , an exemplary fluid control valve 10 generally includes a body 20 that defines an inlet 22, an outlet 24, and a passage 26 disposed between the inlet 22 and the outlet 24. An internal component assembly 100 is disposed within the body 20, and a valve cover 30 is secured to the body 20, for example, using threaded elements 40 and nuts 42 to retain the internal component assembly 100 within the body 20. The internal component assembly 100 generally includes a seat ring 110, a valve cage 120, a first plug assembly 200, and a second plug assembly 300.

[0042] The seat ring 110 is a standard cylindrical or annular seat ring known in the art, and the seat ring 110 is disposed in the passage 26 of the body 20, between the inlet 22 and the outlet 24, to provide a seat surface for engagement with the first plug assembly 200.

[0043] The valve cage 120 is a standard cylindrical valve cage known in the art, and the valve cage 120 is disposed between the inlet 22 and the outlet 24 and adjacent to the seat ring 110, and can be used to secure the seat ring 110 in the passage 26. A plurality of generally radial openings 122 are formed through the wall 124 of the valve cage 120 to permit process fluid to flow from the inlet 22 through the valve cage 120 to the outlet 24. Depending on the particular application, the radial openings 122 can be formed in any size, shape, and / or pattern.

[0044] The first plug assembly 200 is disposed within the valve cage 120 such that the first plug assembly 200 is axially movable (along longitudinal axis A) within the valve cage 120. The first plug assembly 200 includes a first plug 210 that is movable between a closed position ( Figure 1 、 2A 、3A and 3B) and a partially open position ( Figure 3C ) and an open position ( Figure 3D) moves between them, where in the closed position, the first valve plug 210 sealingly engages the seat ring 110 and blocks the process fluid from flowing through the radial openings 122 in the valve cage 120. In the partially open position, the first valve plug 210 separates from the seat ring 110, which allows the process fluid to flow through a part of the radial openings 122 and blocks the process fluid from flowing through another part of the radial openings 122. In the open position, the first valve plug 210 separates from the seat ring 110 and allows the process fluid to flow through the radial openings 122.

[0045] An axial hole 212 is formed on one side of the first valve plug 210, and the axial hole 212 extends longitudinally into the first valve plug 210. The throttle port 214 extends longitudinally through the first valve plug 210, is coaxial with the axial hole 212, and is in fluid communication with the axial hole 212. In addition, the first valve plug assembly 200 includes a plurality of radial holes 202 that are in fluid communication with the axial hole 212. In Figure 1 、 Figure 2A and Figure 2B In the example shown, the radial holes 202 are formed radially through the first valve plug 210. Alternatively, as shown in the example of Figure 9 , the radial holes 202 can also be formed through the retainer of the first valve plug assembly 200 instead of through the first valve plug 210.

[0046] The first valve plug assembly 200 may also have a retainer 230 that is fixed to the first valve plug 210 via threads 232 or any other suitable means. The retainer 230 provides a travel stop for the axial movement of the second valve plug 310 and has an opening 234 for receiving the valve stem 360 of the second valve plug assembly 300, as discussed below. The first valve plug 210, the retainer 230, and the second valve plug 310 together form a cavity 236 for receiving the spring 240 or other biasing member. The spring 240 is disposed within the retainer 230 and between the first valve plug 210 and the second valve plug 310 to bias the second valve plug 310 away from the first valve plug 210 and isolate the spring 240 from the process fluid, keeping the spring 240 outside the flow channel of the process fluid. Keeping the spring 240 outside the flow channel of the process fluid avoids the influence of spring compression on the flow channel. For example, if the spring 240 is in the flow channel, the flow area through the spring 240 will decrease as the spring 240 is compressed. In addition, fluid corrosion of the spring 240 can be avoided or reduced. When the pressure drop on the second valve plug 310 is higher, the fluid velocity becomes higher. Keeping the spring 240 outside the flow channel avoids high-speed fluid corrosion of the spring 140, which extends the service life of the spring 240. As described above, it can be in Figure 9It is observed that the radial hole 202 of the first valve plug assembly 200 can also be formed to radially pass through the retainer 230 instead of passing through the first valve plug 210.

[0047] In addition, as Figure 2B optimally observed in, the first valve plug 210 can have a tapered end 216 adjacent to the end of the first valve plug 210 that engages the seat ring 110 to ensure no flow dead zones and ensure a smooth transition from the first stage cascade flow channel passing through the throttle port 214 to the second stage cascade flow channel formed by the valve cage 120 and the first valve plug 210, as discussed in more detail below.

[0048] The second valve plug assembly 300 is disposed within the axial hole 212 of the first valve plug 210 such that the second valve plug assembly 300 can move axially (along the longitudinal axis A) within the axial hole 212 of the first valve plug assembly 200. The second valve plug assembly 300 includes a second valve plug 310 that can move within the first valve plug assembly 200 between a closed position ( Figure 1 and Figure 3A ) and an open position ( Figure 2A , 3B , 3C and Figure 3D ), wherein in the closed position, the second valve plug 310 sealingly engages the first valve plug 210 and blocks process fluid from flowing through the throttle port 214 of the first valve plug 210, and in the open position, the second valve plug 310 separates from the first valve plug 210 and allows process fluid to flow through the throttle port 214. The second valve plug 310 is guided by the inner diameter of the first valve plug 210 and, in some instances, by the inner diameter of the retainer 230 to ensure concentricity of the second valve plug 310 and the throttle port 214 and a good seal between the second valve plug 310 and the first valve plug 210.

[0049] The valve stem 360 extends through the opening 234 in the retainer 230 and through the opening in the valve cover 30 to connect the second valve plug 310 to a standard actuator (not shown) to move the second valve plug 310 between the open position and the closed position. The second valve plug 310 can also have one or more longitudinally extending holes 312 to pressure balance the second valve plug 310 when it separates from the first valve plug 210 and to pressure balance both the second valve plug 310 and the first valve plug 210 when the second valve plug 310 separates from the first valve plug 210 and the first valve plug 210 separates from the seat ring 110, thereby making the second valve plug 310 and the first valve plug 210 easier to control.

[0050] See Figure 4, the valve tip 314 of the second valve plug 310 includes a generally cylindrical first portion 320 having a diameter D1, where the diameter D1 is greater than the diameter of the throttle port 214. The generally cylindrical second portion 325 has a diameter D2, where the diameter D2 is less than the diameter of the throttle port 214, such that the second portion 325 can be received within the throttle port 214. The seat surface 330 interconnects the first portion 320 and the second portion 325 and engages the first valve plug 210 with the second valve plug 310 in the closed position. In the example shown, the seat surface 330 is generally conical. Additionally, the valve tip 314 and the seat surface of the first valve plug 210 engaged by the valve tip 314 may be made of a hardened material to avoid corrosion of the valve tip 314 and the first valve plug 210.

[0051] To provide more accurate control of the very small flow of process fluid through the throttle port 214, the second valve plug 310 may also be a Micro Tip, or any other type of tip capable of controlling microflows, such as Figure 5 the valve tip 314A shown in. Similar to the valve tip 314, the alternative valve tip 314A includes a first portion 320 having a diameter D1 and a second portion 325 having a diameter D3, where the diameter D1 is greater than the diameter of the throttle port 214 and the diameter D3 is less than the diameter of the throttle port 214. The seat surface 330A interconnects the first portion 320 and the second portion 325 and engages the first valve plug 210 with the second valve plug 310 in the closed position. Different from the valve tip 314, the seat surface 330A of the valve tip 314A is generally perpendicular to the first portion 320 and the second portion 325. Additionally, the valve tip 314A includes: a conical portion 340 extending from the second portion 325 and into the throttle port 214, and a third portion 350 extending from the conical portion 340 and into the throttle port 214. The third portion 350 includes a generally cylindrical portion 352 and an angled planar portion 354 extending downward along the cylindrical portion 352. When the second valve plug 310 is retracted from the first valve plug 210, the valve tip 314A allows the flow of process fluid to increase gradually.

[0052] Figure 6An alternative micro tip is shown. Similar to valve tip 314, alternative valve tip 314B includes a first portion 320 having a diameter D1 and a second portion 325A having a diameter D4, where the diameter D1 is greater than the diameter of the throttle port 214 and the diameter D4 is less than the diameter of the throttle port 214. The seat surface 330B is generally conical, connecting the first portion 320 and the second portion 325A to each other and causing the first valve plug 210 to engage the second valve plug 310 in the closed position. Different from valve tip 314, valve tip 314B includes: a conical portion 340A extending from the second portion 325A and into the throttle port 214, and a third portion 350A extending from the conical portion 340A and into the throttle port 214. The third portion 350A is generally cylindrical and includes one or more grooves 356 whose size can be increased. When the second valve plug 310 retracts from the first valve plug 210, valve tip 314B allows the flow of process fluid to increase gradually. As stated above for valve tip 314, valve tip 314B can be made of hardened material or non-hardened material. In addition, valve tip 314B can be a welded part or a one-piece structure.

[0053] In the fully closed position (see Figure 3A ), the actuator moves the valve stem 360 towards the passage 26, which causes the second valve plug 310 to move into sealed engagement with the first valve plug 210 and causes the first valve plug 210 to move into sealed engagement with the seat ring 110. Thus, the process fluid is prevented from flowing from the inlet 22 to the outlet 24 through the radial openings 122 in the valve cage 120 and through the throttle port 214 in the first valve plug 210.

[0054] When the actuator begins to move the valve stem 360 away from the passage 26 (which causes the second valve plug 310 to move from the closed position ( Figure 3A ) to the open position ( Figure 3B )), the first stage of cascade flow control is achieved. When the valve stem 360 and the second valve plug 310 move away from the first valve plug 210, the spring 240 continues to provide a force between the second valve plug 310 and the first valve plug 210, which maintains the sealed contact of the first valve plug 210 with the seat ring 110. The spring force required by the spring 240 depends on the required structure and load. As Figure 2AAs shown by the arrows in the figure, when the second valve plug 310 is in the open position and the first valve plug 210 is in the closed position, the process fluid can flow from the inlet 22 to the axial hole 212 through a part of the radial opening 122 in the valve cage 120 and through the radial hole 202 in the first valve plug assembly 200. The process fluid can flow from the axial hole 212 through the hole 312 in the second valve plug 310 to balance the pressure of the second valve plug 310, and flow to the outlet 24 through the throttle port 21. The back pressure established when the second valve plug 310 moves away from the first valve plug 210 can protect the tip of the first valve plug 210 from damage. When the second valve plug 310 is fully open and the first valve plug 210 is closed, the process fluid can flow through the throttle port 214. The process fluid can establish a back pressure on the downstream part of the valve, making the pressure drop on the first valve plug 210 smaller. Therefore, when the first valve plug 210 starts to open, the pressure drop is smaller and the velocity of the process fluid is lower, which reduces the fluid erosion on the first valve plug 210 and the seat ring 110, and thus can extend the shut-off life.

[0055] Once the second valve plug 310 is in the fully open position ( Figure 3B ), the second valve plug 310 contacts the top of the holder 230. Once the second valve plug 310 contacts the top of the holder 230, the continuous movement of the valve stem 360 and the second valve plug 310 away from the passage 26 will also move the first valve plug assembly 200 away from the passage 26, and thus move the first valve plug 210 away from the passage 26. When the first valve plug 210 starts to move away from the passage 26 into the partially open position ( Figure 3C ), the second-stage cascade flow control is achieved. The first valve plug 210 will disengage from the seat ring 110 and move to a separated relationship with the seat ring, which allows the process fluid to directly flow through another part of the radial opening 122 in the valve cage 120, through the passage 26, and flow to the outlet 24. When the first valve plug 210 moves away from the passage, the first-stage cascade flow through the radial hole 202 and the throttle port 214 in the first valve plug assembly 200 will become smaller until it is completely closed. When the first valve plug 210 moves away from the seat ring 110, the process fluid can flow through the throttle port 200 and the hole 312 in the second valve plug 310, thereby balancing the pressure of the first valve plug assembly 200 and the second valve plug assembly 300 together, which can make them easier to control and allow the use of a smaller actuator.

[0056] The valve stem 360 will continue to move the first and second valve plug assemblies 200, 300 away from the passage 26 until they reach the rated stroke or the fully open position ( Figure 3D) up to, for example, when the top of the retaining member 230 reaches the valve cover 30. When the first valve plug travels from the partially open position to the fully open position, there will be no flow of the first stage cascade flow through the throttling port 214, and the second stage cascade flow through the radial opening 122 in the valve cage 120 will increase to the maximum.

[0057] When the fluid control valve 10 moves from the fully open position ( Figure 3D ) back to the fully closed position ( Figure 3A ), the first and second valve plug assemblies 200, 300 will first move towards the passage 26 until the first valve plug 210 moves into sealing engagement with the seat ring 110 (see Figure 3B ). When this occurs, the flow of the process fluid through the radial opening 122 in the valve cage 120 is reduced, and thus there is no flow through the throttling port 214. During this movement, the first and second valve plug assemblies 200, 300 remain pressure balanced.

[0058] Once the first valve plug 210 is in sealing engagement with the seat ring 110, the valve stem 360 will continue to move the second valve plug 310 towards the passage 26. When this occurs, the process fluid can flow from the inlet 22 through a part of the radial opening 122 in the valve cage 120 and enter the axial hole 212 through the radial hole 202 in the first valve plug assembly 200. The process fluid can flow from the axial hole 212 through the hole 312 in the second valve plug 310 to pressure balance the second valve plug 310 and flow through the throttling port 214 to the outlet 24. During this movement, the second valve plug 310 remains pressure balanced.

[0059] Once the second valve plug 310 is in sealing engagement with the first valve plug 210, the flow of the process fluid from the inlet 22 to the outlet 24 is blocked, and the first and second valve plug assemblies 200, 300 are no longer pressure balanced. Therefore, no soft seal member is required between the first valve plug assembly 200 and the valve cage 120. This allows the use of the internal component assembly 100 in high-temperature applications with tight shut-off requirements.

[0060] See Figure 7 and Figure 8 , which shows another exemplary fluid control valve 10A that can be used in applications with high pressure drop and low flow. The fluid control valve 10A has the same body 20 and valve cover 30 as the fluid control valve 10 described above. In addition, the internal component assembly 100A of the fluid control valve 10A is similar to the internal component assembly 100 and includes the same seat ring 110 and valve cage 120. Although most of the elements of the first valve plug assembly 200A and the second valve plug assembly 300A are the same as those of the first valve plug assembly 200 and the second valve plug assembly 300, the main difference lies in the engagement surface between the first valve plug 210A and the second valve plug 310A.

[0061] In the first valve plug assembly 200A, the surface 220 of the first valve plug 210A surrounding the throttle port 214 includes a plurality of concentric annular channels 218 that are axially aligned about the throttle port 214. Each channel 218 may have the same width, or as shown in the example of Figure 8 , the width of each channel 218 may be different. In this particular example, the width of each channel is less than the width of the adjacent channel closer to the throttle port 214. Thus, the width W1 of the channel 218 closest to the throttle port 214 is greater than the width W2 of the channel 218 farther from the throttle port 214. The surface 375 of the second valve plug 310A also includes a plurality of annular protrusions 370 that are received in the respective channels 218 to help provide a sealed engagement between the first valve plug 210A and the second valve plug 310A. However, unlike the channels 218, each protrusion has the same width. As the channels get closer to the throttle port 214, the widths W1, W2 of the channels 218 increase, and the widths of the protrusions 370 are formed in the same way to form a multi-stage channel, wherein as the process fluid flows toward the throttle port 214, the size of the flow channel continuously increases. In the example shown in Figure 8 , the flow channel A is smaller than the flow channel B, and the flow channel B is smaller than the flow channel C. This forms an increasing flow channel area to maintain an optimal pressure drop at each stage.

[0062] Figure 9 Another exemplary fluid control valve 10B is shown that provides a simpler design than the fluid control valve 10. In the fluid control valve 10B, the radial hole 202 of the inner component assembly 100B is formed through the retainer 230B of the first valve plug assembly 200B rather than through the first valve plug 210B, and the second valve plug 310B of the second valve plug assembly 300B is simplified such that when the second valve plug 310B is in the closed position in sealed engagement with the first valve plug 210B, the second valve plug 310B does not block the radial hole 202.

[0063] Although various embodiments have been described above, the present disclosure is not intended to be limited thereto. Changes may be made to the disclosed embodiments that still fall within the scope of the appended claims.

Claims

1. A fluid control valve, comprising: a body that defines an inlet, an outlet, and a passage between the inlet and the outlet; a seat ring disposed in the passage; a valve cage disposed between the inlet and the outlet and adjacent to the seat ring, the valve cage including a plurality of radial openings; a first valve plug assembly disposed within the valve cage, the first valve plug assembly including a plurality of radial holes and a first valve plug, the first valve plug having an axial hole in fluid communication with the radial holes and a throttling port in fluid communication with the axial hole, wherein the first valve plug is movable between a closed position and an open position, wherein in the closed position, the first valve plug engages the seat ring, and in the open position, the first valve plug is separated from the seat ring; and a second valve plug assembly disposed within the axial hole of the first valve plug assembly, the second valve plug assembly including a second valve plug, the second valve plug being movable within the first valve plug assembly between a closed position and an open position, wherein in the closed position, the second valve plug engages the first valve plug, and in the open position, the second valve plug is separated from the first valve plug.

2. The fluid control valve according to claim 1, wherein, the plurality of radial holes are formed through the first valve plug.

3. The fluid control valve according to claim 1, wherein: the first valve plug assembly includes a retainer and a spring, the retainer being fixed to the first valve plug, the spring being disposed within the retainer and between the first valve plug and the second valve plug, the spring biasing the second valve plug away from the first valve plug; and the plurality of radial holes are formed through the retainer.

4. The fluid control valve according to claim 3, wherein, the spring is isolated from the process fluid.

5. The fluid control valve according to claim 1, wherein, the first valve plug includes a tapered end.

6. The fluid control valve according to claim 1, wherein, the second valve plug assembly includes a valve stem that connects the second valve plug to an actuator.

7. The fluid control valve according to claim 1, wherein, the second valve plug includes one or more holes therethrough to pressure balance the second valve plug.

8. The fluid control valve according to claim 1, wherein, the second valve plug includes a first portion, a second portion, and a seat surface, the diameter of the first portion being greater than the diameter of the throttling port, the diameter of the second portion being less than the diameter of the throttling port, the seat surface engaging the first valve plug and the second valve plug in the closed position.

9. The fluid control valve according to claim 8, wherein, the second valve plug includes a conical portion extending from the second portion and a third portion extending from the conical portion, the third portion having a generally cylindrical portion and a planar portion.

10. The fluid control valve according to claim 8, wherein, The second valve plug includes a third portion extending from the second portion, the third portion being generally cylindrical and including one or more grooves.

11. The fluid control valve according to claim 1, wherein: the first valve plug includes a plurality of concentric annular channels axially aligned around the throttling port; and the second valve plug includes a plurality of concentric annular protrusions configured to be received in corresponding channels.

12. The fluid control valve according to claim 11, wherein: each channel has a width, wherein the width of each channel is less than the width of an adjacent channel closer to the throttling port; and the plurality of protrusions all have the same width.

13. An internal component assembly for a fluid control valve, the internal component assembly comprising: a seat ring; a valve cage disposed between an inlet and an outlet of the fluid control valve and adjacent to the seat ring, the valve cage including a plurality of radial openings; a first valve plug assembly disposed within the valve cage, the first valve plug assembly including a plurality of radial holes and a first valve plug having an axial hole in fluid communication with the radial holes and a throttling port in fluid communication with the axial hole, wherein the first valve plug is movable between a closed position and an open position, wherein in the closed position, the first valve plug engages the seat ring, and in the open position, the first valve plug is separated from the seat ring; and a second valve plug assembly disposed within the axial hole of the first valve plug assembly, the second valve plug assembly including a second valve plug movable within the first valve plug assembly between a closed position and an open position, wherein in the closed position, the second valve plug engages the first valve plug, and in the open position, the second valve plug is separated from the first valve plug.

14. The internal component assembly according to claim 13, wherein, the plurality of radial holes are formed through the first valve plug.

15. The internal component assembly according to claim 13, wherein: the first valve plug assembly includes a retainer and a spring, the retainer being fixed to the first valve plug, the spring being disposed within the retainer and between the first valve plug and the second valve plug, the spring biasing the second valve plug away from the first valve plug; and the plurality of radial holes are formed through the retainer.

16. The internal component assembly according to claim 15, wherein, the spring is isolated from the process fluid.

17. The internal component assembly according to claim 13, wherein, the second valve plug assembly includes a valve stem connecting the second valve plug to an actuator.

18. The internal component assembly according to claim 13, wherein, the second valve plug includes one or more holes therethrough to pressure balance the second valve plug.

19. The internal component assembly according to claim 13, wherein, The second valve plug includes a first portion, a second portion, and a seat surface, the diameter of the first portion being greater than the diameter of the throttling port, the diameter of the second portion being less than the diameter of the throttling port, and the seat surface engaging the first valve plug and the second valve plug in the closed position.

20. The inner component assembly according to claim 13, wherein: the first valve plug includes a plurality of concentric annular channels axially aligned around the throttling port, each channel having a width, wherein the width of each channel is less than the width of an adjacent channel closer to the throttling port; and the second valve plug includes a plurality of concentric annular protrusions configured to be received in corresponding channels, each protrusion having the same width.

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