WO2010020741A1

WO2010020741A1 - Fluid flow control valve

Info

Publication number: WO2010020741A1
Application number: PCT/GB2009/001771
Authority: WO
Inventors: Trygve Husveg
Original assignee: Typhonix As; Cockbain, Julian
Priority date: 2008-08-20
Filing date: 2009-07-17
Publication date: 2010-02-25

Abstract

The invention provides a fluid flow control valve (60) comprising a cylindrical inlet chamber (61) having a fluid inlet aperture (62) and a coaxial, optionally but preferably waisted, cylindrical outlet chamber (63) having a fluid outlet aperture (64), said inlet chamber containing adjacent first and a second apertured members (68, 69) mutually rotatable between a position in which fluid flow from said inlet aperture to said outlet aperture is permitted and a position in which said flow is prevented or constrained, characterised in that the apertures (67, 70) in at least one of said members are aligned so as to provide fluid flowing therethrough with a velocity component tangential to the axis of said outlet chamber.

Description

Fluid flow control valve

This invention relates to a fluid flow control valve, more particularly a valve for controlling pressure and flow of a two or more phase fluid comprising for example a continuous (e.g. oil or gas) phase and a discontinuous (e.g. water or oil droplet) phase, and to a method of controlling pressure and flow rate of a fluid using such a valve.

In the production and handling of hydrocarbons, e.g. from an oil well, water is frequently present with and hence needs to be separated from the hydrocarbons. Before separation is completed, it may be necessary to control the flow of water containing entrained liquid and gaseous hydrocarbon droplets or bubbles, or of liquid hydrocarbon containing entrained water droplets and gas bubbles , or of gaseous hydrocarbon containing entrained water or oil droplets, etc. Since separation of the entrained droplets is more difficult with smaller droplets, it is important that the handling procedure should not itself cause droplet fragmentation. Equally, in the handling of produced water from hydrocarbon wells it is important not to cause further fragmentation of entrained oil droplets as produced water has to be substantially free of entrained oil droplets before it is returned to the environment. Conventional fluid flow control or choke valves , during fluid flow regulation (e.g. valve closure and opening) can expose the flowing fluid to high shear forces which cause droplet fragmentation and Typhonix AS, in WO2007/024138 (the contents whereof are incorporated herein by reference) , has proposed the use of a control valve in which a rotational flow pattern is imparted to the incoming fluid at the position at which flow rate is altered by the operation of the valve. This is achieved by having the fluid enter a cylindrical inlet chamber through a tangential inlet aperture which can be closed off by axial movement of a piston within that chamber. The rotating fluid passes from an open end of the inlet chamber through a coaxial waisted cylindrical outlet chamber and out of the valve through an outlet aperture in the outlet chamber.

We have now found that control valve performance is enhanced by positioning, between the inlet and outlet chambers to restrict or shut off flow therebetween, apertured members, e.g. discs, which are rotatable relative to each other about an axis substantially parallel to the fluid flow direction between an open and a closed position, and wherein the flow axis through such a valve aperture in the rotatable members has a component parallel to the fluid flow direction and a component perpendicular to the fluid flow direction and to the radial direction relative to the rotation axis. One or both of the members may be rotatable - i.e. one may form a static, indeed integral, part of the valve. The apertures in one or both members will thus be angled relative to the flow direction whereby to impart a tangential component to the velocity of the fluid passing through the apertures .

With this positioning and orientation of valve apertures, energy loss by the fluid transitting the valve is mainly dissipated by virtue of the swirling flow in the outlet chamber and does not result in significant droplet fragmentation.

Thus viewed from one aspect the invention provides a control valve comprising a cylindrical inlet chamber having a fluid inlet aperture and a coaxial, optionally but most preferably waisted, cylindrical outlet chamber having a fluid outlet aperture, said inlet chamber containing adjacent first and second apertured members mutually rotatable between a position in which fluid flow from said inlet aperture to said outlet aperture is permitted and a position in which said flow is prevented or constrained, characterised in that the apertures in at least one of said members are aligned so as to provide fluid flowing therethrough with a velocity component tangential to the axis of said outlet chamber.

Where the valve contains an interior housing incorporating means for rotating the members relative to each other, one member may conveniently be static and form an integral part of that housing. In this event, while that member may have a planar apertured surface perpendicular to the direction of fluid flow through the valve and abutting a corresponding planar apertured surface of the other, rotatable, member, that member obviously need not be in disc, i.e. short cylindrical, form.

The apertures within at least one of said members may, if desired, be aligned so as to provide fluid flowing therethrough with a velocity component towards or away from the axis of fluid flow through the valve. In general however this will not be preferred.

It is also preferred that the cross-sectional areas of the apertures in one such member be substantially similar to those of the corresponding apertures in the other member and that they be positioned so that on rotation they be brought into registry with each other.

Each of the mutually rotatable members may, if desired, be constituted by two or more such adjacent members having apertures which are aligned parallel to the said axis. Thus, if the apertures of two or more such adjacent members are increasingly slightly out of registry, the apertures therein together provide an angled aperture which provides the fluid passing therethrough with the necessary tangential motion. This embodiment however is not preferred and if adopted it is desirable that the edges of the apertures be curved at their margins in the direction curcumferential relative to the said axis .

In a less preferred embodiment, the rotatable members may take the form of nested coaxial cylinders with the valve apertures in the cylinder side walls . If this is the case, the flow apertures will desirably extend in the axial direction of the cylinders as well as being tangentially extensive in the plane perpendicular to this cylinder axis .

The apertures may cause the fluid flowing therethrough to aquire a velocity component tangential to the axis of said outlet chamber either by the shape of the apertures within the rotatable members or, less preferably by being provided with extensions to cause that effect. Thus for example the apertures may be formed by bending out of the surface distal to the other member a flange which provides the fluid with its tangential velocity component.

The rotatable, apertured member (s) can of course be rotated by turning an axle on which it is carried or by driving the rim, e.g. using a cog with teeth engaging with corresponding teeth on the disc's rim.

Thus it can be seen that in such control valves of the invention there are two surfaces rotatably movable relative to each other, at least one of which is apertured having apertures which impart a tangential velocity component to the fluid passing through, and which surfaces can move relative to each other between a position allowing fluid to pass through the valve and a position in which such flow is prevented or constrained.

In the control valve of the invention, the outlet chamber, in the flow path from the valve apertures to the waist (i.e. the waisted portion where the cross- sectional area of the outlet chamber is at its smallest) , is preferably substantially free from intrusive structural elements. Alternatively put, it is preferred that on this flow path the volume filled by fluid extends fully from the inner wall of the outlet chamber to the axis of the outlet chamber. In this way, this volume can be used for energy dissipation, while extra turbulence, which can cause noise, vibration and droplet fragmentation, is avoided.

The term "cylindrical" as used herein is not restricted to forms having purely circular cross- sections and, insofar as the inlet and outlet chambers of the control valve are concerned, is also not restricted to forms having side walls parallel to the axis. Thus for example the cross-section may be elliptical and, for the inlet and outlet chambers, the side walls may converge towards or diverge away from the axis. Circular or substantially circular cross-sections are however preferred. Likewise the term "coaxial" as used herein for two or more items does not require the axes of the items to be identical: they should be in substantially the same direction and substantially adjacent. True coaxiality however is preferred.

In one embodiment of the control valve, the fluid inlet aperture may be arranged to cause fluid entering the inlet chamber to rotate about the cylindrical axis before passing through the valve aperture (s) and into the outlet chamber. Thus, both the fluid inlet aperture and the valve aperture may be arranged to provide a tangential velocity component and such that these components are in the same sense (i.e. the same rotational direction) .

In an alternative embodiment of the control valve, the inlet to the inlet chamber may be axial and the inner walls of the inlet chamber may be provided with structures serving to impart rotational motion to the fluid upstream of the valve apertures. Such structures may for example be vanes, or more preferably spiral grooves and/or ridges on the outer surface of the housing for the rotatable member driving mechanism. Likewise such structures may be vanes or the like connecting or disposed between the outer surface of the housing and the inner surface of the outer wall of the inlet chamber. In this case, the apertures in the rotatable members, if discs, may be axial rather than angled (and if nested cylinders, the apertures may be radial rather than tangential) . Thus viewed from a further aspect the invention also provides a control valve comprising: a cylindrical inlet chamber having an axially disposed fluid inlet aperture; and a coaxial, cylindrical outlet chamber having a fluid outlet aperture; said inlet chamber containing a valve housing carrying adjacent first and second apertured members rotatable relative to each other about the axis of said chambers between a position in which fluid flow from said inlet aperture to said outlet aperture is permitted and a position in which said flow is prevented or constrained; characterised in that the external surface of said housing is shaped to impart rotational motion to fluid flowing from said inlet chamber to said outlet chamber .

The mutually rotatable members, e.g. discs, are preferably provided with a plurality of valve apertures, e.g. up to 100, and these are preferably distributed in a rotationally symmetric manner. The cross-sectional areas of the apertures may be uniform; alternatively they may increase (or decrease) along the cylindrical axis (or the radius) . Likewise the number of apertures per unit length of axis (or unit area of disc) may be uniform or may vary. In this way the rate of onset or cut-off of fluid flow by rotation of the rotatable members may be roughly constant or may be accelerated or decelerated.

Valve apertures in the cylindrical walls or through discs may readily be formed by drilling through the wall or disc.

As used herein "tangential direction" means a direction which neither intersects the cylindrical axis nor is parallel thereto. Preferably it is perpendicular to the axis and preferably it is substantially perpendicular to a radius . While the apertures may be aligned to cause the flow direction therethrough to be in a plane parallel to the main flow axis or a plane perpendicular to the main flow axis, they may if desired be angled such that the flow direction has components both in the axial direction and the radial direction. This may be achieved if the centre points of the inlet and outlet of an aperture are both radially and axially displaced relative to each other.

The valve apertures may be of any desired cross- sectional shape, e.g. circular, regular polygonal, or elongate, for example elliptical or slit-like. The cross-section is preferably smooth and the apertures are preferably slit-like or circular in cross-section - forms which may readily be achieved by cutting or drilling. Where the apertures are elongate in cross- section, e.g. slit-like, the elongation is preferably at least partially and more preferably at least majoratively in the axial direction for cylindrical rotatable members and the radial direction for disc like rotatable members .

The edges of the apertures, especially at the upstream entry, will desirably be smoothed. Moreover, the cross-sectional area of the apertures may increase or, preferably, decrease on passing from upstream to downstream, e.g. they may be substantially frustroconical . For apertures in drum-like rotatable members, the edge of the aperture at the furthest from the axis is preferably substantially tangential at its downstream exit into the interior.

Rotation of the rotatable members by a valve actuator may be by any convenient means, e.g. by a rod penetrating the end of the inlet chamber through a sealed aperture. Operation of the valve actuator may be manual or, more preferably, by a drive motor. Thus for example the rod and the aperture in the inlet chamber through which it passes may be threaded so that rotation of the rod from outside causes the rotatable member (s) to rotate relative to each other. It is particularly preferred that rotation should allow fluid flow through the valve to be stopped.

As mentioned above, the outlet chamber in the control valve is of waisted cylindrical form. By this is meant that the internal cross-sectional area decreases and then increases in the flow direction. The internal diameter at the waist is preferably from 10 to 90% of the internal diameter at the inlet of the outlet chamber, especially 20 to 50%. The maximum internal diameter of the outlet chamber downstream of the waist is preferably 10 to 200% of the internal diameter at the inlet of the outlet chamber, especially 20 to 150%, more especially 50 to 150%. The ratio of axial length from inlet to waist to waist to outlet aperture is preferably 0.1:1 to 10:1, more preferably 0.2:1 to 10:1, particularly 0.2:1 to 5:1, e.g. 0.5:1 to 5:1. The internal surface in the flow direction may be a stepped linear form but preferably is smoothly curved.

To prevent undesired shear forces on the fluid that has passed through the valve apertures, it is particularly preferred that the internal region following the valve apertures to the waist of the outlet chamber be free of valve components intruding into or constraining flow of the fluid. Likewise it is preferred that the side wall of this region in the flow direction should be substantially smooth, i.e. that there should be no sharp stepwise reduction in cross-sectional area. The internal surface roughness should preferably be kept to a minimum.

The ratio of the internal diameter at the inlet of the outlet chamber to the internal length of the outlet chamber is preferably 1:1 to 1:20, especially 1:2 to 1:10.

The inner surface of the valve will generally be smooth in the axial direction between the downstream end of the rotatable members and the exit of the outlet chamber. In the axial direction, the waist occurs between these two end points and the smooth surface may change in the flow direction from parabolic to hyperbolic. If along this surface, the point of minimum diameter (the waist) is designated B, the downstream end of the rotatable members A, the exit of the outlet chamber C, and a point outside the valve on a radius from the cylindrical axis through B is designated D, then angle ABD is preferably 10-85°, especially 20-80°, particularly 30-70°, and angle CBD is preferably 40-87°, especially 50-85°, particularly 60-80°. Hence the angle ABC is preferably 50-172°, especially 70-165°, particularly 90-150°.

The fluid outlet aperture in the outlet chamber is preferably at the end remote from the inlet end. The aperture may be in the end of the chamber, preferably at the axis, or alternatively it may be in the side wall. If the outlet aperture is off-axis, it is preferably oriented to remove fluid from the outlet chamber in a tangential direction. It is particularly preferred that the end of the outlet chamber remote from the inlet chamber be the outlet aperture.

A vortex breaker is preferably positioned in or after the outlet chamber so as to remove the rotational motion of the exiting fluid. Such a breaker may take the form of a set of plates or tubes parallel to the cylinder axis or mean flow direction. Where a vortex breaker is positioned within the outlet chamber, it is preferably positioned downstream of the waist so as to avoid generating extra turbulence in the volume upstream of the waist .

It is especially preferred that the vortex breaker comprise surfaces (e.g. axially and radially extending vanes) having an angle to the axis of the outlet chamber that decreases in the flow direction and which, were flow to be reversed, would impart a rotational motion to a linearly flowing fluid. Such vanes are significantly more effective than simple planar surfaces aligned parallel to the axis. Thus for example tests have shown that the noise level during operation may be reduced by a quarter or more. Desirably, the surfaces are aligned such that at their upstream end they are close to parallel (e.g. within 10°) to the "helical" flow direction of the fluid reaching them from the waist, and that at their downstream end they are close to parallel to the axis. In this way, the transfer from rotating to linear flow may be achieved most smoothly and with the minimum of noise and vibration.

The control valves are preferably provided with external flanges about the inlet and outlet apertures so that fluid may be fed into the valve and removed from the valve through conduits attached to those flanges.

If desired, the valves may include a further valve upstream of the fluid inlet aperture or downstream of the fluid outlet aperture.

The chambers and rotatable members will typically be of plastics or, more preferably, metal, e.g. carbon or stainless steel, cast or forged steel, or cast iron, optionally together with an erosion resistant surface or surface coating such as tungsten carbide, titanium carbide, polycrystalline diamond, or a ceramic.

As mentioned above, the valves of the invention are particularly suited for use in controlling flow of two or three phase fluids, e.g. emulsions and dispersions, for convenience referred to herein as emulsions. The valves are especially suited for use with gases with entrained liquid droplets or from which liquid droplets are released on passage through the valve apertures and outlet chamber, and for use with liquids with entrained liquid droplets.

Thus viewed from a further aspect the invention provides a method of altering flow rate or pressure of an emulsion through a conduit comprising a valve by operation of said valve, characterized in that said valve is a valve according to the present invention.

In the method of the invention, the emulsion is preferably a hydrocarbon-in-water emulsion ( e. g. produced water) , a water-in-hydrocarbon emulsion, or a liquid in gas dispersion (e.g. an aerosol) . In the method, the conduit preferably connects the valve to an upstream and/or downstream phase separator, e.g. a gravity or cyclone separator.

In the control valve of the invention, the cyclonic flow towards the waist in the outlet chamber contributes substantially to the overall pressure drop, thus permitting a lesser pressure drop on transitting the valve apertures and thereby causing less droplet fragmentation for the same overall pressure drop. Thus the combination of the waist and a downstream vortex breaker results in an overall reduction in turbulence in the region following the valve apertures during valve operation. The avoidance of structural elements in the flow from valve apertures to waist further contributes to this avoidance of turbulence and improvement of valve function. Likewise, the use of apertures which are both tangentially and axially oriented results in lower pressure drop on transitting the valve apertures and less peak maximum turbulence in the region from valve apertures to waist. As a result of the combination of two or more of these features, the control valve is thus suited for use with fluids with entrained droplets of either higher or lower density.

Since the valves of the invention reduce droplet fragmentation, one result is that the effective viscosity of the fluid downstream of the valve is less than with a conventional valve making the valves of the invention particularly suitable for use with more viscous liquids, for example heavy crude oils, since the energy needed to cause the liquids to flow is reduced and the need for drag-reducing chemical additives is reduced or avoided. The valves are thus particularly suitable for use as subsea choke valves, e.g. upstream of risers and transportation pipelines.

The invention will now be described further with reference to the accompanying drawings, in which:

Figure 1 is a schematic longitudinal cross-section through a first valve according to the invention;

Figure 2 is a longitudinal cross-section through a second valve according to the invention;

Figure 3 is a schematic view of a control valve of the type shown in Figure 1 ;

Figure 4 is a schematic view of a control valve of the type shown in Figure 1 ;

Figure 5 is a schematic view of a control valve of the type shown in Figure 1 ;

Figure 6 is a schematic axial section through relatively rotatable disc-like rotatable members in a valve such as that of Figure 1;

Figure 7 is a schematic axial section through relatively rotatable cylindrical rotatable members in a valve such as that of Figure 2;

Figure 8 is a partial schematic axial view of a downstream disc-like rotatable member of a valve such as that of Figure 1; and

Figure 9 is a schematic perspective view of a vortex breaker as shown in Figure 1.

Referring to Figures 1 and 2 there is shown a control valve 1 having a cylindrical inlet chamber 2 with an axially positioned fluid inlet aperture 3 and having a coaxial waisted cylindrical outlet chamber 4 with an axially positioned fluid outlet aperture 5.

Within the inlet chamber 2 are located two coaxial members 6 held by casing 7, rotatable relative to each other, and provided with valve apertures 8 between the inlet and outlet chambers. Casing 7 contains a transmission unit 9 arranged to rotate coaxial members 6 relative to each other to seal or unseal the valve apertures. Transmission unit 9 operates to transform rotational motion of stem 10 produced by external drive motor 11 into rotational motion of the rotatable members .

Inlet aperture 3 is attached to inlet pipe 12 at flange 13. Outlet aperture 5 is attached to outlet pipe 14 at flange 15. Inlet and outlet pipes 12 and 14 as shown have the same internal diameter.

The internal surface of outlet chamber 4 upstream of waist 16 is at 30° to the axis of the chamber in the axial direction, i.e. the cone angle is 60°. Downstream of the waist the angle varies smoothly.

Within the downstream end of outlet chamber is disposed a vortex breaker 17.

In the embodiment shown in Figure 1, the apertured rotatable members are in the form of discs 18, 19 arranged adjacent in the axial direction. In the embodiment shown in Figure 2 , the apertured rotatable members are in the form of drums 20, 21 adjacent in the radial direction. In both embodiments, one or both such members may be static with the other rotatable relative to it.

Referring to Figures 3 to 5, there is shown a fluid flow control valve 60 having an inlet chamber 61 with an inlet aperture 62 and an outlet chamber 63 having a convergent exit chamber 72 leading to an outlet aperture 64 (itself optionally, but most preferably, connected to a divergent chamber (not shown) ) . Fairing 65 in inlet chamber 61 has vanes 66 which impart a tangential component to the fluid flowing through the valve leading the fluid to apertures 67 in an upstream disc 68. Adjacent disc 68 is a downstream disc 69 which can be rotated relative to disc 68 by rotation of control handle 71. (The relative rotation can of course be achieved by rotation of either or both discs) . Downstream disc 69 has apertures 70 of various decreasing cross-sectional areas whereby rotation of downstream disc 69 causes fluid flow through the valve to be decreased and stopped. Apertures 70 are angled to maintain the tangential component of the velocity of the fluid flowing therethrough.

Referring to Figure 6, there is shown a valve body 72 having a static apertured member 73 arranged perpendicular to the valve axis 74. Adjacent static member 73 is a rotatable apertured disc 75, also perpendicular to the valve axis. Rotatable disc 75 is coupled to a drive means (not shown) by shaft 76. The apertures 77 in static member 73 and rotatable disc 75 may be brought into alignment by rotation of disc 75 under the action of the drive means . The apertures are angled with respect to the valve axis (radially) and also circumferentially as indicated by the dashed lines showing the aperture walls behind the plane of the Figure .

Referring to Figure 7, there is shown a valve body 78 having a static, cylindrical apertured member 79 arranged coaxially with the valve axis 80. Adjacent static member 79 is a rotatable apertured cylinder 81, also coaxial with the valve axis. Rotatable cylinder 81 is coupled to a drive means (not shown) by shaft 82. The apertures 83 in static member 79 and rotatable cylinder 81 may be brought into alignment by rotation of cylinder 81 under the action of the drive means. The apertures are angled with respect to the valve axis (radially) and also circumferentially as indicated by the dashed lines showing the aperture walls behind the plane of the Figure .

Referring to Figure 8 , there is shown a rotatable disc-like member 84 (e.g. the downstream rotatable member 6 in a valve as shown in Figure 1) , seen from the upstream side. Disc-like member 84 has apertures 85 formed by bending out-of-plane, in the downstream direction, flanges 86 formed by cutting the disc along lines 87 and 88.

Referring to Figure 9, there is shown a perspective view of a vortex breaker 89 arranged on the valve axis 90. The vortex breaker has four blades 91 each with an upstream edge 92 and a downstream edge 93 rotated relative to each other about the valve axis such that the downstream end of each blade is substantially parallel to the valve axis .

Claims

B2009/001771- 16 - Claims :

1. A fluid flow control valve (60) comprising a cylindrical inlet chamber (61) having a fluid inlet aperture (62) and a coaxial cylindrical outlet chamber (63) having a fluid outlet aperture (64), said inlet chamber containing adjacent first and a second apertured members (68, 69) mutually rotatable between a position in which fluid flow from said inlet aperture to said outlet aperture is permitted and a position in which said flow is prevented or constrained, characterised in that the apertures (67, 70) in at least one of said members are aligned so as to provide fluid flowing therethrough with a velocity component tangential to the axis of said outlet chamber.

2. A control valve (60) comprising: a cylindrical inlet chamber (61) having an axially disposed fluid inlet aperture (62); and a coaxial, cylindrical outlet chamber (63) having a fluid outlet aperture (64); said inlet chamber containing a valve housing (65) carrying adjacent first and second apertured members (68, 69) rotatable relative to each other about the axis of said chambers between a position in which fluid flow from said inlet aperture to said outlet aperture is permitted and a position in which said flow is prevented or constrained; characterised in that the external surface of said housing is shaped to impart rotational motion to fluid flowing from said inlet chamber to said outlet chamber .

3. A valve as claimed in either of claims 1 and 2 wherein said outlet chamber is waisted.

4. A valve as claimed in claim 4 wherein a vortex breaker is positioned in said outlet chamber downstream of the waisted portion thereof.

5. A valve as claimed in claim 4 wherein said vortex breaker comprises radially and axially extending vanes the fluid impact surfaces whereof are at a progressively decreasing angle relative to the axis of said outlet chamber from the end proximal to said members to the end distal to said members .

6. A valve as claimed in any one of claims 2 to 5 wherein said outlet chamber is substantially free from intrusive structural elements in the fluid flow path from said members to the waisted portion of said outlet chamber .

7. A valve as claimed in any one of claims 1 to 6 wherein said members are adjacent in the axial direction.

8. A valve as claimed in any one of claims 1 to 7 wherein in one of said members the centre points of said apertures at the entrance and exit thereof are displaced relative to each other in both the radial and axial directions .

9. A valve as claimed in any one of claims 1 to 8 wherein one of said members is fixed.

10. A valve as claimed in any one of claims 1 to 9 wherein said fluid inlet aperture and said fluid outlet aperture are substantially coaxial with said inlet and outlet chambers.

11. A method of altering flow rate or pressure of an emulsion through a conduit comprising a valve by operation of said valve, characterized in that said valve is a valve according to any one of claims 1 to 10.

12. A method as claimed in claim 11 wherein the density of the continuous phase of the emulsion is greater than that of the discontinuous phase.