GB2618602A

GB2618602A - Trim component and valve

Info

Publication number: GB2618602A
Application number: GB2206972.8A
Authority: GB
Inventors: Sundar Raju Shivendra; James Preston Timothy; Michael Root Paul
Original assignee: Goodwin PLC
Current assignee: Goodwin PLC
Priority date: 2022-05-12
Filing date: 2022-05-12
Publication date: 2023-11-15
Also published as: GB202206972D0

Abstract

Trim or cage component 81 for controlling flow parameters in a valve, the trim having a longitudinal axis L and comprising a plurality of radial channels 84 each having an interior surface 85 which is inclined relative to a plane perpendicular to the longitudinal axis of the trim. The channels may be cylindrical, conical, or slots. An upper end of each slot may comprise the inclined surface. A lower end 86 of each slot may be parallel to the surface or extend perpendicular to the trim axis. The trim may be annular, and single or multi-stage. Also claimed is a trim comprising a plurality of radial channels, a cross section of a radially outer portion of each channel being larger than that of a radially inner portion to form a concave step 137 at a radially outer opening of the channel. Each opening may have a chamfer, fillet, or a blended, progressive or lead-in radius. Also claimed is a valve comprising a valve body, and a trim component comprising a plurality of radial channels, where a concave step for promoting local flow separation is formed by an increase in flow path area at a location upstream of the channels. The valve may be an axial valve.

Description

TRIM COMPONENT AND VALVE

BACKGROUND TO THE INVENTION

The present invention relates to trim component for a valve, and a valve comprising such a trim component. A trim component, which may also be known as a trim, a cage, a trim cage, a throttle cage, or a plug, is a part which can be inserted into a valve in order to control flow parameters through the valve. A trim component typically includes a plurality of openings through which fluid can flow, whilst also including some portions which can block fluid flow. The design of such a component (including the area through which fluid can flow) thus can be used to control the flow parameters of fluid as the fluid flows through the valve.

Such a trim component may be interchangeable, such that for a given design of valve, the flow parameters through the valve can be controlled as desired.

In an axial flow valve, which uses a movable piston, the movement of which controls the opening and closing of the valve, a trim component may be placed in the flow path upstream of the piston in order to provide additional control over the parameters of flow in the valve. Such a trim component is typically annular (ring shaped), and includes a plurality of openings allowing fluid to flow therethrough. Typically, in an axial flow valve with an annular trim component, fluid flows from the radially outer surface of the trim component to the radially inner surface of the trim component, and subsequently to the outlet of the valve.

Various types of trim components for axial flows valves are known. Single stage trim components comprise a single annulus through which fluid can flow. Multi stage trim components are also known, where a plurality of concentric annular stages are provided. In such an arrangement, each stage typically comprises a plurality of openings allowing flow from the radially outer surface to the radially inner surface of the stage, with circumferential grooves being provided to allow fluid to flow from the radially inner surface of one stage to the openings in the subsequent stage.

When a trim component (of any of the types described above) is used, the interaction between the fluid flow and the trim component, as well as between the fluid flow and other components of the valve, may cause flow separation and/or cavitation. This may be especially evident when there is a large pressure drop between the inlet and outlet of the valve, which may cause cavitation and consequent erosion. This in turn may lead to one or more of a loss in overall capacity of the valve, wear of the valve components, generation of undesirable noise, and reduces valve performance.

It is an aim of the present invention to at least partially address the problems above.

SUMMARY OF THE INVENTION

According to a first aspect, there is provided a trim component for controlling flow parameters in a valve, the trim component having a longitudinal axis and comprising a plurality of channels providing fluid communication between a radially outer surface and a radially inner surface of the trim component, wherein the channels each have an interior inclined surface which is inclined toward the flow direction relative to a plane perpendicular to the longitudinal axis of the trim component.

Optionally, a plurality of said channels are distributed in a direction parallel to the longitudinal axis of the trim component.

Optionally, the channels are cylindrical.

Optionally, the channels are conical.

Optionally, the channels are slots elongate in a direction parallel to the longitudinal axis, and each inclined surface is at an upstream end of a respective slot Optionally, each slot further comprises a second interior inclined surface, at a downstream end of the slot, which is inclined towards the flow direction relative to a plane perpendicular to the longitudinal axis of the trim component.

Optionally, the inclined surfaces at the upstream and downstream end of each respective slot are parallel to each other.

Optionally, each slot comprises a surface at the downstream end of the slot which is parallel to a plane perpendicular to the axis of the trim component.

Optionally, the interior inclined surface is inclined toward the flow direction relative to a plane perpendicular to the longitudinal axis of the trim component at an angle of 5 degrees or greater.

Optionally, the interior inclined surface is inclined toward the flow direction relative to a plane perpendicular to the longitudinal axis of the trim component at an angle of 25-40 degrees, and preferably 25-35 degrees. These angle ranges may be preferable where the channels are distributed in a direction parallel to the longitudinal axis of the trim component, and are thus a plurality of holes.

Optionally, the interior inclined surface is inclined toward the flow direction relative to a plane perpendicular to the longitudinal axis of the trim component at an angle of 25-50 degrees, and preferably 30-50 degrees. These angle ranges may be preferable where the channels are elongate slots.

Optionally, the trim component is annular.

Optionally, the trim component is a single stage trim component formed of a single annulus Optionally, the trim component is a multi-stage trim component including a plurality of concentric annuluses, wherein said channels are provided in at least one of said annuluses.

In another aspect, there is provided a trim component for controlling flow parameters in a valve, the trim component having a longitudinal axis and comprising a plurality of channels providing fluid communication between a radially outer surface and a radially inner surface of the trim component, wherein the channels each comprise a radially inner portion and a radially outer portion, the cross section of the radially outer portion being larger than the cross section of the radially inner portion, to thereby form a concave step around at least a portion of an opening of the channel at the radially outer surface.

Optionally, the trim component is a multi-stage trim component comprising a first stage and a second stage, wherein the first stage is positioned radially outward of the second stage said plurality of channels, radially inner portion, radially outer portion and concave step are provided in the second stage, and the first stage comprises a further plurality of channels providing fluid communication between a first surface and a second surface of the first stage Optionally, the radially outer portion is a first cylindrical portion, and the radially inner portion is a second cylindrical portion, the radius of the first cylindrical portion being larger than the radius of the second cylindrical portion.

Optionally, the trim component is removable from the valve.

Optionally, the channels each have a longitudinal axis, and the longitudinal axes of the channels pass through the longitudinal axis of the trim component.

Optionally, the channels each have a longitudinal axis, and the longitudinal axes of the channels do not pass through the longitudinal axis of the trim component.

Optionally, each channel is provided with an edge preparation at one or more of its openings.

Optionally, the edge preparation is a chamfer, a fillet, a blended radius, a progressive radius or a lead-in radius.

In another aspect, there is provided a valve comprising the trim component of any of the aspects described above Optionally, the valve is an axial flow valve, and said inclined surface is inclined toward the flow direction relative to the radial direction of the valve Optionally, a concave step for promoting local flow separation is formed at a location upstream of the channels of the trim component.

In another aspect, there is provided a valve having a flow path therethrough, and comprising a valve body and a trim component configured to control flow parameters through the valve, wherein the trim component includes a plurality of channels providing fluid communication between a radially outer surface and a radially inner surface of the trim component, and a concave step for promoting local flow separation is formed by an increase in flow path area at a location upstream of the channels.

Optionally, said concave step is formed at an interface of the valve body and the trim component.

Optionally, said concave step is formed in the surface of said trim component.

Optionally, said concave step is formed in the surface of said valve body.

Optionally, the increase in flow path area is 5% or more.

Optionally, said concave step is configured so as to promote flow reattachment downstream of the step.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described, by way of non-limitative example only, with reference to the following drawings, in which: Figure 1 shows a section view of a known axial piston valve including a trim component, Figure 2a shows a perspective view of a known trim component; Figure 2b shows a section view of the known trim component of Figure 2a, Figure 3a shows a perspective view of a first arrangement of trim component according to the present invention; Figure 3b shows a section view of the trim component of Figure 3a; Figure 4a shows a CFD simulation of flow streamlines through the trim component of Figures 2a and 2b; Figure 4b shows a CFD simulation of flow velocity through the trim component of Figures 2a and 2b; Figure 5a shows a CFD simulation of flow streamlines through the trim component of Figures 3a and 3b, Figure 5b shows a CFD simulation of flow velocity through the trim component of Figures 3a and 3b Figure 6a shows a perspective view of a known trim component; Figure 6b shows a section view of the trim component of Figure 6a; Figure 7a shows a perspective view of a second arrangement of trim component according to the present invention, Figure 7b shows a section view of the trim component of Figure 7a; Figure 8a shows a perspective view of a third arrangement of trim component according to the present invention; Figure 8b shows a section view of the trim component of Figure 8a; Figure 9a shows a CFD simulation of flow streamlines through the known trim component of Figures Oa and 6b; Figure 9b shows a CFD simulation of flow velocity through the known trim component of Figures 6a and 6b; Figure 10a shows a CFD simulation of flow streamlines through the trim component of Figures 7a and 7b; Figure 10b shows a CFD simulation of flow velocity through the trim component of Figures 7a and 7b; Figure lla shows a CFD simulation of flow streamlines through the trim component of Figures 8a and 8b, Figure llb shows a CFD simulation of flow velocity through the trim component of Figures 8a and 8b, Figure 12a shows a frontal section view of a known multistage trim component; Figure 12b shows an enlarged cutaway of a part of Figure 12a; Figure 13a shows a frontal section view of a fourth arrangement of trim component according to the present invention; Figure 13b shows an enlarged cutaway of a part of Figure 13a; Figure 14a shows a simplified representation of frontal section of a trim component according to the present invention; and Figure 14b shows a simplified representation of frontal section of another trim component according to the present invention.

DETAILED DESCRIPTION

The present invention relates to a trim component for a valve, and a valve comprising such a trim component.

A schematic section view of a known axial flow valve is shown in Figure 1. The valve 10 comprises an inlet 11 and an outlet 12, with fluid flowing from the inlet 11 to the outlet 12 when the valve is open and in use. The valve is opened and closed by axial translation of piston 13. That is, in the view shown in Figure 1, the valve is open, because piston 13 is retracted (i.e. to the left in the view shown in Figure 1) and does not block fluid flow passage 15. On the other hand, when the valve is closed (not shown), the piston 13 moves to the right in the view shown in Figure 1, and at least partially blocks the passage. When the valve is closed, the piston completely blocks the passage so that fluid cannot flow through the valve.

The valve also comprises a trim component 14. In this arrangement, the trim component is positioned in the flow passage 15, upstream of the location of the piston 13 when the valve is closed. It will be noted that trim component 14 comprises a plurality of openings allowing fluid to pass through, which in the arrangement shown in Figure 1 are elongate slots.

Figures 2a and 2b illustrate an arrangement of known trim component for use with the valve depicted in Figure 1. Rather than a plurality of elongate slots (as shown in Figure 1), the trim component of Figures 2a and 2b includes a plurality of cylindrical holes.

It will be seen from Figure 2a that the trim component has a generally annular shape, with a longitudinal axial [passing through the middle of the annulus. The plurality of cylindrical holes act as channels, or passages, which provide fluid communication between the radially outer surface 22 of the trim component to the radially inner surface 23 of the trim component. Thus, when the trim component is in use in a valve and the valve is at least partially open, flow passes through channels 24 from radially outer surface 22 to radially inner surface 23, and subsequently to the outlet 12 of the valve.

It will be noted from Figure 2b that channels 24 extend parallel to the radial direction of the annulus. In other words, the channels are disposed so that their interior surfaces, along their length, are parallel to a plane perpendicular to the longitudinal axis L of the trim component 21. It will be apparent from Figures 2a and 2b that the channels 24 are distributed both circumferentially around the annulus of the trim component (and thus circumferentially around the longitudinal axis L of the trim component), and also distributed axially along the surface of the trim component (i.e. distributed in a direction parallel to the longitudinal axis L of the trim component 21).

Figures 3a and 3b illustrate a first arrangement of trim component 31 according to the present invention. Trim component 31 has a generally similar form to trim component 21, being annular and comprising a plurality of channels passing from radially outer surface 32 to radially inner surface 33, and thus providing fluid communication between radially outer surface 32 and radially inner surface 33. Likewise, channels 34 are distributed both circumferentially around the annulus of the trim component (and thus circumferentially around the longitudinal axis L of the trim component), and also distributed axially along the surface of the trim component (i.e. distributed in a direction parallel to the longitudinal axis L of the trim component 31).

However, contrary to the known arrangement of Figures 2a and 2b, in the arrangement of Figures 3a and 3b, channels 34 are not parallel to a plane perpendicular to the longitudinal axis of the trim component, but are rather inclined relative to such a plane. In other words, the channels have an interior surface and a longitudinal axis which is inclined relative to the radial direction of the trim component. Further, the direction of inclination is toward the flow direction, relative to the plane perpendicular to the longitudinal axis of the trim component. In other words, when moving from the radially outer surface 32 of the trim component to the radially inner surface 33 of the trim component, the flow moves not only radially, but additionally in the same direction as the direction of flow through the valve (i.e. from left to right in the view shown in Figures I and 3b). That is, the channels are arranged so as to introduce an axial vector component (in relation to the trim) into the flow, in a direction from the inlet towards the outlet. It will be understood that the channels being inclined also results in the channels having an interior inclined surface which is inclined in the same manner. That is, the interior inclined surface is formed by the wall of the channel.

Although the channels are distributed in a direction parallel to the longitudinal axis L of the trim component 31, as explained above, it will be understood that the channels need not all be distributed along the same line along the surface in the axial direction, and may be at different circumferential positions around the annulus.

Figures 4a, 4b, 5a and 5b show CFD simulations of flow in typical flow conditions in a valve through trims 21 and 31 respectively. It will be seen that in Figures 4a and 4b, when the known trim component 21 shown in Figures 2a and 2b is used, flow separation (shown by areas of recirculation in Figure 4a, and by the darker areas corresponding to lower velocity in Figure 4b) occurs at the entrance of each of channels 24 and through the channels. There are also regions of separated flow immediately downstream of the channels, and a larger region of separated flow further downstream of the trim (at the top of the flow area in the view shown in Figures 4a and 4b, which corresponds to the radially outer portion of the flow passage).

On the other hand, in Figures 5a and 5b, when trim component 31 shown in Figures 3a and 3b, is used, the flow stays attached on entry to the channels (which are inclined in the manner described above), and through the channels. Further, the amount of flow separation immediately downstream of the channels, and downstream of the trim as a whole, is reduced. This is illustrated by the streamlines in Figure 5a showing less recirculation (particularly in the radially outer region of the passage downstream of the trim component), and by the velocity plot in Figure 5b showing both smaller areas of low velocity (associated with separation) and an overall lighter colour when taken (i.e. averaged) over the passage as a whole. This in turn may have numerous advantages, including better utilisation of flow area through the valve and an associated increase in valve capacity, reduced turbulence inside the trim and downstream of the trim, and consequent reduction in noise. Thus, the trims of the present invention may result in improvements in the efficiency of the valve itself, as well as improved control over the flow parameters through the valves due to the increased performance of the trim.

It will be understood that the geometric parameters of the trim shown in Figures 3a and 3b may readily be varied. The channels depicted in Figures 3a and Figure 3b are in the form of cylindrical holes (i.e, each hole has a constant diameter along its length). However, other arrangements are possible, such as the holes being conical (i.e. with differing diameter along their length). In arrangements where a conical hole is used, the hole may either diverge or converge along its length.

Further, one or more of the openings of the hole (i.e the entrance to and/or exit of the hole) may have shaping in order to smooth the transition between the surface of the trim and the interior of the holes, and thus further improve the flow regime through the holes. For example, an edge preparation such as a chamfer or fillet maybe present at the entrance and/or exit of each hole (i.e. at the radially outer or radially inner surface of the trim component), or a small countersunk bore may be provided at the entrance and/or exit of each hole. As a further example of an edge preparation, a blended radius, a progressive radius, or a lead-in radius may also be provided at the opening of the hole. That is, the corner" where the hole meets the surface of the trim may be given a radius. This may result in the diameter of the hole at (and in the region of) the entrance of the hole being 1 I_ different to that away from the entrance of the hole. For a hole of diameter D, in some arrangements the diameter of the hole (measured perpendicular to the longitudinal axis of the hole) at the opening may be 1.1D to 2.0D, preferably 1.2D-1.6D and most preferably 1.3D. It will be understood that the large diameter of hole opening may vary from its larger value to the diameter D, thus providing a blended, progressive or lead-in radius. Such a variation may be gradual, may be linear between the two diameters or may vary according to a predetermined shape (such as a standard, as described below). It will be understood that not all of the holes need have an edge preparation (i.e. only a subset of the holes may have such an edge preparation), and that different edge preparations may be applied to different holes.

In some arrangements, the shape of the edge preparation may have a profile corresponding to a standard. One example of a suitable standard is a DIN standard, and in particular the DIN 333R standard. However, it will be understood that other standards may also be suitable. Such an edge preparation may be manufactured using either a custom made or a standard tool in order to achieve the desired shape. In some examples, the shape may be provided by drilling, and where the profile corresponds to a standard, using a drill corresponding to that particular standard.

In the arrangement shown in Figures 3a and 3b described above, the interior surface of the channels forms an interior inclined surface. The angle of inclination may vary according to the desired flow conditions, but in general the angle of inclination relative to the plane perpendicular to the axis (i.e. measured from the radial direction) is 5 degrees or greater. In some arrangements, the angle of inclination may be 10-60 degrees, 20-60 degrees, preferably 25-45 degrees, more preferably 25-40 degrees, and most preferably 25-35 degrees. In some preferable arrangements, the angle may be 25 degrees, 30 degrees or 35 degrees. The ranges and angles set out above may provide a particularly marked reduction in flow separation and subsequent increase in capacity of the valve.

It will be appreciated that although in the arrangement shown in Figure 3b, the angle of inclination of each channel is the same (and the channels are thus all parallel to each other), arrangements are also possible in which the angle of inclination varies between channels, such that the channels are not parallel to each other.

Figures 6a and 6b illustrate a further arrangement of known trim component 61. Similarly to the known trim component shown in Figures 2a and 2b, trim component 61 is of annular shape. A plurality of channels 64 providing fluid communication between radially outer surface 62 and radially inner surface 63 are provided. However, rather than the channels being holes distributed in the axial direction (as in the arrangement of Figures 2a and 2b), the channels are elongate slots, which are elongate in a direction parallel to the longitudinal axis L of the trim component 61. The channels are distributed circumferentially around the trim component (and thus also distributed circumferentially around longitudinal axis L).

In the known arrangement shown in Figure 6b, upstream end 65 and downstream end 66 of the slots are parallel to the radial direction. In other words, they are parallel to the plane perpendicular to longitudinal axis L of trim component 61. It will be understood that the terms "upstream end" and "downstream end" refer to the upstream and downstream directions defined by flow through the valve as a whole. Thus, although flow through the trim component is from the radially outer surface to the radially inner surface of the trim component, the upstream end of the slot (i.e. the interior surface of the slot, at the end of the slot closest to the upstream side of the trim component) is the end on the left of the view shown in Figure 6b, and the downstream end of the slot (i.e. the interior surface of the slot, at the end of the slot closest to the downstream side of the trim component) is the end on the right of the view shown in Figure 6b.

Figures 7a and 7b illustrate a second arrangement of trim component according to the present invention. Trim component 71 shown in Figures 7a and 7b has a generally similar form to that shown in Figures 6a and 6b, with a plurality of channels 74 providing fluid communication between radially outer surface 72 and radially inner surface 73. However, contrary to the known arrangement shown in Figures 6a and 6b, upstream surface 75 of each channel is inclined relative to a plane perpendicular to the longitudinal axis of the trim component, thus forming an inclined surface. In other words, the inclined surface in each slot is inclined relative to the radial direction. Further, the direction of inclination is toward the flow direction, relative to the plane perpendicular to the longitudinal axis of the trim component. In other words, when moving from the radially outer surface 62 of the trim component to the radially inner surface 63 of the trim component, the flow moves not only radially, but additionally in the same direction as the direction of flow through the valve (i.e. from right to left in the view shown in Figure 6b).

It will be noted that in the arrangement shown in Figure 7a and 7b, downstream surface 76 of channels 74 is parallel to the radial direction, and thus also parallel to a plane perpendicular to longitudinal axis L. Figures 8a and 8b show a third arrangement of trim component according to the present invention. The trim component 81 shown in Figures 8a and 8b is substantially similar to that shown in Figure 7a and 7b, but differs in that downstream surface 86 of each channel is also inclined similarly to upstream surface 85. That is, downstream surface is inclined relative to the radial direction, and relative to a plane perpendicular to the longitudinal axis of the trim component. The inclination is in a direction toward the flow direction. Thus, upstream surface 85 forms a first interior inclined surface, and downstream surface 86 forms a second interior inclined surface.

In the arrangement shown Figure 8b, the second interior inclined surface 86 is parallel to the first interior inclined surface 85. However, it will be understood that second interior incline surface 86 may be inclined relative to a plane perpendicular to the longitudinal axis of the trim component, but at a different angle to the angle of inclination of upstream surface 85.

In the arrangements of Figures 7a, 7b, 8a and 8b, an inclined surface is present in the channels. In the arrangement of Figures 8a and 8b, a first inclined surface (at the upstream end) and a second inclined surface (at the downstream end) is present. The angle of inclination of these inclined surfaces may vary according to the desired flow conditions, but in general the angle of inclination relative to the plane (i.e. measured from the radial direction) perpendicular to the axis is 5 degrees or greater. In some arrangements, the angle of inclination may be 10-60 degrees, 20-60 degrees, preferably 30-50 degrees, more preferably 30-40 degrees and most preferably 35-40 degrees. In some preferable arrangements, the angle may be 30 degrees, 35 degrees or 40 degrees.

It will be understood that the edge preparations described above in relation to Figures 3a and 3b may also be applied to the arrangements of Figures 7a, 7b, 8a and 8b, at locations where the inclined surfaces meet the other surfaces of the trim.

Figures 9a and 9b show a CFD simulation of flow through known trim component 61 illustrated in Figures Ga and 6b, which has upstream and downstream ends that are parallel to the radial direction and parallel to each other. It will be noted that flow separation starts at upstream edge of the trim component (i.e. where the flow enters trim component 61), and that large regions of flow separation are present downstream to the trim component, on both sides of the main flow.

Figures 10a and 10b show a CFD simulation of flow through trim component 71 shown in Figures 7a and 7b, but with otherwise similar conditions to the simulation shown in Figures 9a and 9b. It will be noted that flow stays attached through the trim component (when passing over upstream surface 75), and that the size of the regions of separated flow is reduced on both sides of the main flow. Likewise, in Figures 11 a and 11b, which show a CFD simulation of the flow through trim component 81 shown in Figures 8a and 8b, the flow remains attached over both the first and second inclined surfaces, and the size of the regions of separated flow is further reduced.

In a further aspect of the invention, when a trim (such as the trims described above) is installed in a valve, the trim and valve may be arranged such that a concave step is formed at a location upstream of the channels of the trim component. An example of such a step 101 is shown, for example, in Figures 10a, 10b, lla and I lb, where a concave step is formed at the interface between the valve and the trim components 71, 81. The concave step 101 is thus positioned upstream of the channels formed in the trim component. The step results in an increased flow path area after the step, compared to before the step.

The step may be formed such that so that the step promotes local flow separation in the area immediately adjacent the concave step 101. This small area of local flow separation may promote reattachment of the flow further downstream of the step and area of local flow separation, and result in an overall reduction in flow separation downstream of the step.

The exact dimensions of such a step in order to promote local flow separation depends on the flow conditions and the dimensions of the valve and the trim. However, an increase in flow path area of 5% or more is typically sufficient to promote local flow separation and reattachment of the flow further downstream.

Although such a step is shown in particular in Figures 10a, 10b, lla and 11b, it will be understood that such a step may be provided upstream of the openings of any of the trim components of the present invention.

Although the step described above is formed at an interface between a surface of the valve and a surface of the trim component, it will be understood that such a step need not be formed at such an interface, and may alternatively or be formed only in the surface of the valve, or only in the surface of a trim component The trim components according to the present invention illustrated in Figures 3a, 3b, 7a, 7b and 8a, and 8b are all single stage trim components. That is, they are formed of a single annulus, with flow entering the trim component at a radially outer surface of the annulus and existing the trim component at a radially inner surface of the same annulus. However, the present invention may also apply to multistage trim components, in which a plurality of concentric annuluses is provided.

Within a multistage trim, fluid flow typically passes from a radially outer surface of a first annulus to a radially inner surface of the first annulus, through a groove in the outer surface of a second annulus, and then from a radially outer surface of a second annulus to a radially inner surface of the second annulus. Where further stages are present, flow passes between subsequent annuluses in the same way. It will be understood that any number of stages may be provided in a multistage trim. The number of stages may be chosen based on the particular application of the valve in which the trim is to be used, the pressure drop across the valve and the desired flow parameters.

Figures 12a and 12b illustrate a known arrangement of multistage trim 120. In the arrangement shown in these Figures, the multistage trim 120 is a three stage trim, comprising a first stage 121, a second stage 122 and a third stage 123. First stage 121 comprises a plurality of channels 124 providing fluid communication between its radially outer surface and its radially inner surface, second stage 122 comprises a plurality of channels 125 providing fluid communication between its radially outer surface and its radially inner surface, and third stage 123 comprises a plurality of channels 126 providing fluid communication between its radially outer surface and its radially inner surface.

The channels in successive stages are offset circumferentially relative to each other, such that flow cannot pass in a straight line through the channels in two successive stages In order to allow flow between subsequent stages, circumferential grooves are provided on the radially outer surface of the second and third stages, such that flow can pass through the channels in the first stage, around the grooves in the radially outer surface of the second stage, and into the channels in the second stage. Likewise, the channels in the radially outer surface of the third stage allows flow to pass through the channels in the second stage, around the grooves in the radially outer surface of the third stage, and into the channels in the third stage.

Thus, as shown by the arrows in Figures 12b, flow passes through channels 124, then into channels 125 and then into channels 126, thus passing from the radially outer surface of the multistage trim to the radially inner surface of the multistage trim. It will be appreciated that because the view of Figures 12a and 12b is a view looking along the axial direction, the circumferential grooves through which fluid flows from the channels of the first stage to the channels of the second stage, and likewise from the channels of the second stage to the third stage, are not visible.

Figures 13a and 13b illustrate a multistage trim according to a fourth arrangement of the present invention. Multistage trim 130 is similar in form to multistage trim 120. However, the channels 135 of the second stage 132, and channels 136 of the third stage 133, have a larger radius at their radially outer opening than the radius of the rest of the channel. This results in each of the channels 135 and 136 having a radially outer portion and a radially inner portion, with the cross section of the radially outer portion being larger than the cross section of the radially inner portion. This results in a concave step 137 being formed around at least a portion of the opening of each channel at the radially outer surface of the each of the second and third stages. That is, at the opening of each channel 135 in the second stage 132, a concave step 137 is formed, and at the opening of each channel 136 in the third stage 133, a concave step 137 is formed. The concave step 137 can also be considered to act as a small countersunk bore at the opening of the channel.

Such a concave step 137 may result in a small area of separated flow at the step itself Such a small region of local flow separation may promote reattachment of the flow downstream of the step, resulting in reduced separation of the flow downstream of the step, and an overall reduction in area of separated flow, hi turn, this may improve the capacity of the valve. Such a concave step may also be particularly effective in reducing cavitation, which might otherwise occur in the flow as is passes through the multistage trim. In turn, this may reduce wear and erosion of the trim component, and reduce noise generated by cavitation. It will be understood that concave steps 137 are another example, applied to a multi stage trim, of a concave step formed up upstream of the channels formed in the trim component, as described above in relation to Figures 10a, 10b, 11 a and 11b.

In arrangements where the channels are circular holes, the radially outer portion is formed as a first cylindrical portion, and the radially inner portion is formed as a second cylindrical portion, with the diameter of the first cylindrical portion being larger than the diameter of the second cylindrical portion.

It will be appreciated that in the arrangement shown in Figures 13a and 13b, such a step is present at the radially outer surfaces of the second and third stages. That is, the step is provided at all of the stages except the radially outermost stage. However, other arrangements are possible in which such a step is present only in the radially innermost stage, or at only an intermediate stage of the multistage trim, or at all stages of the multistage trim. It has been found that such a step is most advantageous at stages other than the radially outermost stage.

In the arrangement described above, all of the channels in the second and third stages include a concave step 137. However, alternative arrangements are also possible where only a subset of the channels of a particular stage include such a step. For example, channels may alternate between a channel with a concave step and a channel without a concave step, or in any other suitable pattern.

Such an arrangement with a concave step may also be applied to single stage trims, such as those described above. For example, a concave step may be provided at the opening of some or all of the holes of the trim illustrated in Figures 3a and 3b, or at the opening of some or all of the elongate slots in the other arrangements described above.

It will also be understood that a multistage trim component may also be provided with the features shown in the single stage trim components shown in Figures 3a, 3b, 7a, 7b, 8a and 8b and described above. That is, in a multistage trim component, the above arrangements of channels including an inclined surface (i.e. including holes and/or slots) may be applied to a multistage trim, with the channels including inclined surfaces being provided in one stage of the multistage trim, a subset of the stages of the multistage trim, or all of the stages of the multistage trim. Where such channels are not provided in some of the stages, the channels through those stages may be similar to the known arrangements shown in Figures 2a, 2b, 6a and 6b.

It will also be understood that although the figures of the present application show arrangements in which the fluid flow is from left to right in the views shown, the valve itself may also be used in reverse That is, in the view shown in Figure 1, flow may enter the valve through passage described above as outlet 12, and exit the valve through the passage described above as inlet 11 In this arrangement, the fluid flows through the channels from the radially inner surface of the trim component to the radially outer surface of the trim component (i.e. in the reverse direction to what is described above). In this situation, it will be understood that the flow direction in Figures 1, 4a, 4b, 9a, 9b, 10a, 10b, lla and 11 b will be from right to left, and that the flow direction in figures 12a and 13a will be radially outward (i.e. bottom to top in figures 12b and 13b). In these arrangements, the inclination of the channels is toward the flow direction when the flow travels from the radially inner surface of the trim component to the radially outer surface of the trim component.

In any of the arrangements set out above (including single stage and multistage trims), the channels may extend between the radially inner and radially outer surfaces of the trim at the same circumferential position (i.e. at the same angular position around the annulus), and thus have openings at the same angular position on the radially inner and outer surfaces. That is, the channels may lie on a plane which is parallel to the longitudinal axis of the trim and passes through the longitudinal axis of the trim. In other words, the longitudinal axes of the channels pass through the centre point of the annulus (and thus through the longitudinal axis of the trim). This may apply regardless of whether the channels are holes or elongate slots. It will be understand that in these arrangements, the channels do not introduce any tangential velocity component (i.e. swirl) into the flow. Such a lack of swirl may contribute to the increase in capacity of the valve described above.

An example of such an arrangement is shown in Figure 14a, which is a simplified frontal cross-section (i.e. viewed along the direction of longitudinal axis L) showing only four channels 144a around the annulus of trim 141a, for the sake of clarity. It will be understood that this figure is merely schematic, and the size of the channels relative to the size of the trim in this figure is not to scale, and that there may be any number of channels around the annulus (as shown in, for example, Figure 3a). It will be noted that the longitudinal axes C of the channels pass through the longitudinal axis L of the trim 141a.

In other arrangements, the radially outer surface of the trim may be linked by the channels to a different circumferential position at the radially inner surface of the trim, and the channels thus have openings at the different angular positions on the radially inner and outer surfaces. That is, the channels may be inclined relative to (i.e. not lie on) a plane which is parallel to the longitudinal axis of the trim, and when the line of the channel from the radially outer to the radially inner surface is extended, the line does not pass through the longitudinal axis of the trim. In other words, the longitudinal axes of the channels do not pass through the centre point of the annulus (and thus do not pass through the longitudinal axis of the trim). . It will be understand that in these arrangements, the channels introduce a tangential velocity component (i.e. swirl), in addition to an axial velocity component, into the flow. This may be desirable in certain applications. In this arrangement, the channels are inclined in two directions. First, they are inclined relative to a plane perpendicular to the longitudinal axis (as described above in relation to, for example, Figures 3a and 3b), and are additionally inclined in the manner described in this paragraph. This may apply regardless of whether the channels are holes or elongate slots.

An example of such an arrangement is shown in Figure 14b, which is a simplified frontal cross-section (i.e. viewed along the direction of longitudinal axis L) showing only four channels 144b around the annulus of trim 14 lb, for the sake of clarity. It will be understood that this figure is merely schematic, and that the size of the channels relative to the size of the trim in this figure is not to scale, and that there may be any number of channels around the annulus (as shown in, for example, Figures 3a). It will be noted that the longitudinal axes C of the channels do not pass through the longitudinal axis L of the trim 141a. It will be understood that in some arrangements, a combination of channels of the types shown in Figures 14a and 14b is possible.

Although the above arrangements have been described in the context of a trim component for use in an axial flow valve, it will be understood that the above arrangements are equally applicable to trim components used in other types of control valve, such as radial flow valves, ball valves, angle choke valves, angle seat valves, or globe valves.

It should be understood by those skilled in the art that while the present invention has been described with reference to exemplary embodiments, it is not limited to the disclosed exemplary embodiments Various modifications, combinations, sub-combinations and alterations may occur depending on design requirements and other factors insofar as they are within the scope of the appended claims or the equivalents thereof Features from any example or embodiment of the present disclosure can be combined with features from any other example or embodiment of the present disclosure.

Claims

CLAIMS1. A trim component for controlling flow parameters in a valve, the trim component having a longitudinal axis and comprising a plurality of channels providing fluid communication between a radially outer surface and a radially inner surface of the trim component; wherein the channels each have an interior inclined surface which is inclined relative to a plane perpendicular to the longitudinal axis of the trim component.
2. The trim component of claim 1, wherein a plurality of said channels are distributed in a direction parallel to the longitudinal axis of the trim component.
3. The valve according to claim 1 or 2, wherein the channels are cylindrical.
4, The valve according to claim 1 or 2, wherein the channels are conical.
5. The trim component of claim 1, wherein the channels are slots elongate in a direction parallel to the longitudinal axis, and each inclined surface is at an upstream end of a respective slot.
6. The trim component of claim 5, wherein each slot further comprises a second interior inclined surface, at a downstream end of the slot, which is inclined relative to a plane perpendicular to the longitudinal axis of the trim component
7. The trim component of claim 6, wherein the inclined surfaces at the upstream and downstream end of each respective slot are parallel to each other.
8. The trim component of claim 5, wherein each slot comprises a surface at the downstream end of the slot which is parallel to a plane perpendicular to the axis of the trim 30 component.
9. The trim component of any preceding claim, wherein the interior inclined surface is inclined toward the flow direction relative to a plane perpendicular to the longitudinal axis of the trim component at an angle 5 degrees or greater.
10. The trim component of any preceding claim, wherein the interior inclined surface is inclined toward the flow direction relative to a plane perpendicular to the longitudinal axis of the trim component at an angle of 25-40 degrees, and preferably 25-35 degrees.
11. The trim component of any of claims 1-9, wherein the interior inclined surface is inclined toward the flow direction relative to a plane perpendicular to the longitudinal axis of the trim component at an angle of 25-50 degrees, and preferably 30-50 degrees.
12. The trim component of any preceding claim, wherein the trim component is annular.
13 The trim component according to claim 12, wherein the trim component is a single stage trim component formed of a single annulus.
14. The valve according to claim 12, wherein the trim component is a multi-stage trim component including a plurality of concentric annuluses, wherein said channels are provided in at least one of said annuluses.
15. A trim component for controlling flow parameters in a valve, the trim component having a longitudinal axis and comprising a plurality of channels providing fluid communication between a radially outer surface and a radially inner surface of the trim component; wherein the channels each comprise a radially inner portion and a radially outer portion, the cross section of the radially outer portion being larger than the cross section of the radially inner portion, to thereby form a concave step around at least a portion of an opening of the channel at the radially outer surface.
16. The trim component of claim 15, wherein the trim component is a multi-stage trim component comprising a first stage and a second stage; wherein: the first stage is positioned radially outward of the second stage; and said plurality of channels, radially inner portion, radially outer portion and concave step are provided in the second stage; and the first stage comprises a further plurality of channels providing fluid communication between a first surface and a second surface of the first stage.
17. The trim component of claim 15 or 16, wherein the radially outer portion is a first cylindrical portion, and the radially inner portion is a second cylindrical portion, the radius of the first cylindrical portion being larger than the radius of the second cylindrical portion
18. The trim component of preceding claim, wherein the trim component is removable from the valve.
19. The trim component of any preceding claim, wherein the channels each have a longitudinal axis, and the longitudinal axes of the channels pass through the longitudinal axis of the trim component.
20. The trim component of any of claims 1-18, wherein the channels each have a longitudinal axis, and the longitudinal axes of the channels do not pass through the longitudinal axis of the trim component.
21. The trim component of any preceding claim, wherein each channel is provided with an edge preparation at one or more of its openings.22. The trim component of claim 21, wherein the edge preparation is a chamfer, a fillet, a blended radius, a progressive radius or a lead-in radius.
22. A valve comprising the trim component of any preceding claim.
23. The valve according to claim 22, wherein the valve is an axial flow valve, and said inclined surface is inclined toward the flow direction relative to the radial direction of the valve.
24. The valve of claim 22 or 23, wherein a concave step for promoting local flow separation is formed at a location upstream of the channels of the trim component.
25. A valve haying a flow path therethrough, and comprising a valve body and a trim component configured to control flow parameters through the valve, wherein: the trim component includes a plurality of channels providing fluid communication between a radially outer surface and a radially inner surface of the trim component; and a concave step for promoting local flow separation is formed by an increase in flow path area at a location upstream of the channels
26 The valve according to claim 27, wherein said concave step is formed at an interface of the valve body and the trim component.
27. The valve according claim 25, wherein said concave step is formed in the surface of said trim component.
28. The valve according claim 25, wherein said concave step is formed in the surface of said valve body.
29. The valve according to any one of claims 25-28, wherein the increase in flow path area is 5% or more.
30. The valve according to any one of claims 25-29, wherein said concave step is configured so as to promote flow reattachment downstream of the step