WO2014071991A1

WO2014071991A1 - Mesh

Info

Publication number: WO2014071991A1
Application number: PCT/EP2012/072288
Authority: WO
Inventors: Mohamed Reda Akdim
Original assignee: FMC Separation Systems BV
Current assignee: FMC Separation Systems BV
Priority date: 2012-11-09
Filing date: 2012-11-09
Publication date: 2014-05-15
Anticipated expiration: 2015-05-09

Abstract

The present invention provides a mesh for separation of liquids dispersed in a fluid stream, said mesh comprising a base section (7) and a surrounding wall (6), wherein the cross-sectional area of the wall, the cross-section being perpendicular to a centerline (Y) of the base section or a centerline (Y) of the wall, increases with the distance from the base section.

Description

MESH

Field of the invention

The present invention concerns a mesh suitable for the separation of liquids from gas. The mesh according to the invention is also suitable for dispersing liquid droplets in a gas stream

Background

In the production of oil and or gas it is important to separate the supplied gas and liquid mixtures, for instance into a flow consisting essentially of gas and a flow consisting essentially of liquid. It may also be important to get the gas as day as possible of to get any liquid as evenly disbursed as possible. Various devices are known for the separation of such gas/liquid mixtures.

One such separation device is commonly named a demister or agglomerator, depending on the gas load factor. In a demister/agglomerator, a gas/liquid mixture is supplied via a channel and led through a wire mesh, also referred to as a mesh pad, arranged in the channel. Liquid, for instance as a fine mist or droplets, dispersed in the gas/liquid mixture, collide with the wires of the wire mesh and

coalesce/agglomerate. In an agglomerator, which is more or less a demister which is run at a higher gas load factor, the dispersed liquid forms a liquid layer which is drained out of the mesh. The mesh is commonly furnished with drains to facilitate the draining of the liquid away from the mesh and to the bottom of the separation device. In such separation devices, the mesh is usually a planar pad which is situated horizontally in a vertical channel.

A disadvantage with the prior art demisters/agglomerators is that when the mesh is flooded, the liquid can only enter the drain by diffusion which is a slow process.

Thus, flooding limits the maximum flow rate of the demister/agglomerator, which again leads to separating devices having a relatively large circumference due to the required size of the mesh.

Patent application WO 03/095069 discloses a device for separation of liquids from a fluid stream. A mesh is arranged in the upper part of a horizontal pipe. The mesh consists of two mesh plats joined at an angle to provide a larger mesh area, and is provided with multiple vanes to lead the fluid stream in a direction perpendicular to the surface of the mesh. Due to its configuration, the mesh is not suitable for a vertical separator, nor will it allow for a comprehensive coverage of the cross- section of such a separator. Patent application GB 946909 discloses a vortex steam separator for separating steam from liquid.

The goal of the present invention is to alleviate or avoid at least some of the disadvantages of the prior art meshes and of their corresponding use in gas/liquid separators and liquid distributors.

Summary of the invention

The present invention provides a mesh which alleviates or avoids at least some of the drawbacks of the prior art mesh solutions. By having a mesh of a substantially conical or pyramidal shape, the mesh will have an increased surface area compared to a corresponding planar mesh. The use of a mesh according to the present invention will thus lead to a separating device of increased capacity compared to a similarly sized separating device using the prior art mesh. Alternatively, the mesh according to the present invention may be used to construct a separating device having the same capacity as a larger separating device using a prior art mesh, and thereby obtaining a substantially lighter and or smaller device. Further, liquids that are formed or gathered in the mesh according to the invention are much easier to drain since the inclination of the walls will lead the liquids towards the optional drain hole at the base section or drain hole at an outer circumference of the mesh. Due to the drainage effect, a mesh according to the present invention will have a larger fluid stream capacity than a prior art mesh having the same effective area. The present invention comprises the use of such mesh in devices for separating liquids from gas, and in devices for dispersing liquids in a fluid flow, as well as such devices per se. The invention is further defined in the following and by the attached claims.

The present invention regards a mesh for separation of liquids dispersed in a fluid stream or possibly dispersing liquid droplet evenly in a gas flow. According to the invention the mesh comprises a base section and a surrounding wall. The wall being formed such that a cross-sectional area of the wall, the cross-section being perpendicular to a centerline of the base section or possibly a centerline of the wall, increases with the distance from the base section. This will give a, at least partly cone or abutted cone shaped form of the surrounding wall. The cone may be formed with a circular circumference or it may be formed by a set of wall elements forming a multisided circumference. The cross-section of the wall may be as said

substantially circular, elliptic or polygonal. According to an aspect the cross-section may be polygonal and chosen from a group comprising pentagonal, hexagonal, heptagonal and octagonal. According to an aspect of the invention the mesh may be formed such that the cross-sectional area increases in a linear, non-linear or stepwise manner. The increase is seen in a direction away from the base section. The mesh may be positioned such that the base section part of the mesh is positioned in an upstream or downstream position relative the surrounding walls. Normal flow direction through the mesh, as it is normally positioned in a vessel with mainly vertically walls, would be a flow direction from below and upwards through the mesh. Said with other words the largest cross sectional area of the surrounding wall may be positioned at an upstream end of the mesh. Alternatively, the larger cross sectional area of the surrounding wall may be positioned at a downstream end of the mesh. During normal use the mesh may be positioned with the base section relatively vertically below the surrounding wall, or alternatively vertically above the surrounding wall.

According to another aspect of the invention an inner surface of the wall in the mesh may comprise at least one trough or gutter, situated such that the liquids are led towards the base section. The inner surface being a surface partly facing another part of the inner surface of the surrounding wall. An outer surface being a surface facing a vessel wherein the mesh is positioned. The trough or gutter may extend from an outer circumference of the surrounding wall to the base section, or possibly from a position in a distance from the outer circumference of the surrounding wall and to the base section. There may also be formed trough or gutters in the base section, as a possible continuation of the trough or gutter in the surrounding wall. This would normally be the case where in use of the mesh the base section is positioned vertically below the surrounding walls. In another embodiment the outer surface may comprise at least one trough or gutter. This trough or gutter may extend from the base section to the outer circumference or possibly from a position in a distance from the base section to the outer circumference of the surrounding wall.

In another embodiment at least one trough or gutter may be formed such that they extend through the mesh, thereby guiding liquid in the whole depth of the mesh towards the base section. Extends through should be understood to extend from an upstream side to a downstream side of the mesh, or extend from an inside to an outside of the wall.

According to another aspect the base section may comprise at least one drainage hole. According to another aspect the mesh may comprise at least one drainage hole in an outer circumference of the mesh. This may be formed in the wall or in a holding structure arranged between the surrounding wall and a wall of the vessel wherein the mesh is positioned. This drainage hole may be a at least partly annular shaped hole or possibly several holes around the circumference or several partly annular shaped holes around the circumference. The troughs of gutter may in one embodiment be connected to this drainage hole. The drainage hole may comprise a pipe element leading down to a position below a normal liquid level positioned below the mesh.

According to another aspect the base section may comprise a liquid collector. The liquid collector may be connected to the drainage hole. The liquid collector may be connected to the troughs or gutters.

According to another aspect the surrounding wall may comprise a plurality of planar mesh plates, said plates preferably having a substantially isosceles trapezium configuration. According to another aspect the mesh may comprise a support at the circumference of the wall opposite the base section, the support being able to cover any space formed between the circumference of the wall and an inner surface of a vessel within which the mesh is arranged. The support may comprise at least one drainage hole. According to an embodiment the support may comprises a rib or lip formed as a trough, said lip or rib may optionally be connected to troughs in the mesh wall. The rib or lip may comprise a drainage hole. According to another aspect the mesh according to the invention may comprise a holding structure. The holding structure may be formed with a base part and a wall part, wherein elements with an internal mesh configuration forming the base section, and the surrounding wall, are positioned. In one embodiment the troughs may be formed by the holding structure. The holding structure may be formed to close any gaps between the surrounding walls of the mesh and an internal wall of a vessel wherein the mesh is positioned. According to another aspect the holding structure may comprise support means for attachment to the internal wall of a vessel wherein the mesh is positioned. Drainage holes may be formed in the holding structure, possibly in the base section, the surrounding walls and or the part surrounding the surrounding walls. The base part of the mesh may consist of the holding structure formed with a drainage hole, or alternatively a drainage hole and a trough or alternatively just a part of a holding structure.

According to another aspect of the invention the mesh may be formed with the wall having an average angle of 25-75°, 30-75°, 35-65°, or 45-60°, in relation to the centerline of the base section or the centerline of the wall

According to another aspect the mesh may be formed with the surrounding wall comprised by a plurality of mesh plates with a substantially isosceles trapezium configuration, and wherein at least one mesh plate may be curved in at least one direction and the outside of the curve is facing in a downstream direction. According to another aspect of the invention, the internal mesh configuration of the base section may be different from the internal mesh configuration of the mesh in the surrounding walls. Alternatively a height of the mesh in the base section may be different to the height of the mesh in the surrounding wall. The present invention also regards the use of at least one mesh according to the invention in a liquid/gas-separator, a demister or a liquid disperser.

The present invention also regards a separator device for separation of liquids dispersed in a fluid stream, comprising a substantially vertical channel and at least one mesh according to the invention, wherein the mesh is positioned in the vertical channel, and the channel comprises an inlet for the fluid stream to be separated, a first outlet for the separated liquids, and a second outlet for the separated fluid stream, the mesh is situated above the inlet and the first outlet, and below the second outlet, such that the fluid stream to be separated approaches the mesh from the base section.

According to an aspect the separator device may comprise a base section of the mesh with a drainage hole, and wherein said drainage hole is connected to a drainage channel which comprises an outlet below a liquid level in a bottom part of the separator. In devices for separating liquids from gas or devices for dispersing liquids in a fluid flow, any type of mesh combination may be used. For instance, a device may comprise two mesh according to the invention, or one mesh according to the invention and one prior art mesh, and similar.

The angle of the wall, i.e. its inclination, in relation to a horizontal plane of the base section, should preferably be in the range of 15-60° (corresponding to an angle of 30-75° in relation to the centerline of the base section, or the centerline of the wall). A smaller angle will prevent an effective drainage of the liquid agglomerated in the mesh, as well as providing for a relatively small mesh surface area. If the angle is too large, the required length of the mesh wall, in order for it to cover the cross- sectional area of a vessel, will be too long.

The angle, or inclination, of the wall is not necessarily even along the whole distance from the smallest circumference of the wall to the largest circumference. This is the case when the wall is curved, or is made up of wall sections of differing inclination and similar. In those cases the angle of the inclination, in relation to the centerline of the wall or the base section, is measured by using a virtual line intersecting both the inner surface of the smallest circumference, and the inner surface of the largest circumference of the wall.

Short description of the drawings

Fig. 1 shows a cross-section of a prior art Fig. 2 shows a cross-section of an embodiment of a mesh according to the invention.

Fig. 3 shows a top view, and a cross-section, of an embodiment according to the invention, compared to a prior art mesh. Fig. 4 shows an isometric view of the embodiment in fig. 3.

Fig. 5 shows a top view, and a cross-section, of an embodiment according to the invention, compared to a prior art mesh.

Fig. 6 shows an isometric view of the embodiment in fig. 5.

Fig. 7 shows a cross-section of an embodiment of a mesh according to the invention.

Fig. 8 shows a cross-section of an embodiment of a mesh according to the invention.

Detailed description of the drawings

A prior art mesh is shown in fig. 1. The presently shown mesh has a planar mesh pad 1 arranged in a horizontal direction, and comprises troughs 2 to facilitate the drainage of liquids from the mesh and through the drainage holes 3. The drainage holes 3 are connected to downcomers 4 or vertical channels, which lead the drained liquid below the liquid level of the separation vessel in which the mesh is arranged. The mesh is attached to the surrounding separation vessel by fastenings means 5.

An embodiment of a mesh according to the present invention is shown in fig. 2. The mesh comprises a mesh wall 6 connected to a base section 7. In this embodiment, the base section 7 comprises a liquid collector 12. The wall 6 is angled in relation to the base section/co Hector 7, 12 forming a funnel-like or cone- like configuration. The angled wall 6 facilitates the drainage of any liquid which coalesce in or on the mesh wall. The top of the mesh wall is connected to an inner surface of a

surrounding vessel by fastening means 5. The surrounding vessel may be a vertical channel-part of a separator for separating liquids from gas. The fastening means 5 may for instance be a lip or rib which optionally closes off any space formed between the top of the mesh wall and the surrounding vessel. The lip or rip may in addition be shaped as a trough connected to the troughs 2 formed on the inner surface of the mesh wall.

A further embodiment of the invention is shown in fig. 3. The embodiment is shown together with a prior art mesh 8 having a planar and horizontal configuration. In this embodiment, the base section 7 of the mesh according to the invention does not comprise a drainage hole or collector. The mesh may be constructed of separate polygonal mesh plates 9,10. In this embodiment, the wall 6 is made up of six mesh plates 9 having an isosceles trapezium configuration with two parallel sides B and B', and the base section of a hexagonal mesh plate 10. The mesh is shown arranged within a circular channel 1 1 , wherein the channel have an outer and inner diameter A and A' . Alternatively, the mesh may be constructed wherein the wall and/or the base section is made in one piece of mesh. Another possibility is to form the walls of an element with an internal mesh configuration which has a smaller depth compared with an element with an internal mesh configuration forming part of the base section. In the embodiment of fig. 3, the liquid which is formed will drain through the mesh itself and not via a separate drainage hole in the base section. The wall is inclined at an angle a with respect to a horizontal plane, or a plane of a planar part of the base section. In table 1 , the effective area Al of the mesh is shown in relation to the angle a. A2 is the area of the corresponding prior art mesh, see fig. 4. As shown in the table, the effective area Al increases exponentially with the size of the angle. However, the height h (or length) of the mesh in a vertical direction will also increase exponentially as the angle increases, and to obtain a practical sized mesh, the size of the angle will be have to be restricted. The measurements shown in fig. 3, for instance the lengths of the parallel sides of the trapezium and the diameter A' of the vessel, are only for illustrative purposes to show how the mesh area increase in relation to the angle a, and do not constitute any restriction with regards to the size or proportions of the mesh.

A preferred mesh will have an angle a between about 15° to about 65°, between about 25° to about 60°, between about 25° to about 55°, or between about 30° to about 45°.

The angle a of the inclination of the wall may also be expressed in relation to the centerline Y of the base section or of the wall. The preferred range of the angle of the wall in relation to said centerline is between about 30° to about 75°, from about 35° to about 65°, or from about 45° to about 60°.

Table 1

An isometric view of the mesh according to the present invention, and the prior art mesh 8, shown in fig. 3, is shown in fig. 4. A further embodiment of the mesh according to the invention is shown in fig. 5. A prior art mesh having a planar and horizontal configuration is shown in comparison. The overall configuration of the mesh is similar to the embodiments of fig. 3 and 4 described above. However, the mesh shown in fig. 5 comprises two additional features to improve the drainage capacity. In this particular embodiment the base section 7 is configured as a drainage hole/liquid collector for draining the liquids formed in or on top of the mesh. To further facilitate draining of the liquids, the mesh wall is arranged with five troughs 2 or gutters. The prior art mesh also comprises troughs 2' (fig. 6). The angle a of the wall 6 contributes significantly to the drainage capacity of the mesh and thus the fluid flow capacity of a separator device within which the mesh is used. As for the embodiments shown in fig. 3 and 4, the size of the angle a is likewise restricted due to the resulting length of the mesh. In addition, the drainage capacity will also be affected by the angle a, requiring a certain minimum angle for the liquids to be drained effectively. In table 2, the effective area Al , and height h, of the mesh is shown as a function of the angle a.

Table 2

An isometric view of the mesh according to the present invention, and the prior art mesh 8, shown in fig. 5, is shown in fig. 6.

A further embodiment of a mesh is shown in fig. 7. In this case the mesh is situated in a vertical channel 13, arranged with the base section 7 at the topside of the mesh, i.e. the base section is arranged downstream with regards to the largest

circumference of the mesh wall 6. Troughs or gutters 2 are arranged on the upstream side of the mesh wall 6, i.e. on the outer surface of the wall. The mesh is connected to the vertical channel 13 by support 5, which in this case acts as a gutter for collecting liquids which drain from the mesh wall. The support features drainage holes 3 connected to downcomers 4. The downcomers have an outlet situated below the liquid level of the vertical channel 13. Thus, at least parts of the liquid which coalesce or agglomerate on the topside of the mesh, or in the mesh interior, will drain to the support 5 and through the downcomers 4. A simplified embodiment of the mesh shown in fig. 7 is depicted in fig. 8. As with the mesh in fig. 7, the mesh in fig. 8 is situated in a vertical channel 13, arranged with the base section 7 at the topside of the mesh. The support 5 connects the mesh to the surrounding vertical channel, covering any space between the wall of the vertical channel 13 and the outermost circumference of the mesh wall 6. In this embodiment the formed liquids will drain downstream through the mesh wall 6 or base section 7 without the use of any supplementary drainage facilities, such as troughs and drainage holes.

Claims

A mesh for separation of liquids dispersed in a fluid stream, said mesh comprising a base section (7) and a surrounding wall (6), wherein the cross-sectional area of the wall, the cross-section being perpendicular to a centerline (Y) of the base section or a centerline (Y) of the wall, increases with the distance from the base section.

The mesh according to claim 1 , wherein the cross-sectional area increases in a linear, non-linear or stepwise manner.

The mesh according to claim 1 or 2, wherein the cross-section of the wall is substantially circular, elliptic or polygonal.

The mesh according to any of the preceding claims, wherein an inner surface of the wall (6) comprises at least one trough (2) or gutter, extending at least in part between the largest circumference of the inner surface of the wall (6) and the base section (7).

The mesh according to any of the preceding claims, wherein the base section (7) comprises a drainage hole (3).

The mesh according to claims 1 , 2 or 3, wherein an outer surface of the wall comprises at least one trough (2) or gutter, extending at least in part between the largest circumference of the outer surface of the wall and the base section (7).

The mesh according to any of the preceding claims, wherein the surrounding wall comprises a plurality of planar mesh plates, said plates preferably having a substantially isosceles trapezium configuration

The mesh according to any of the preceding claims, wherein the wall has an average angle of about 25-75°, 30-75°, 35-65°, or 45-60°, in relation to the centerline (Y) of the base section (7) or the centerline (Y) of the wall (6).

The mesh according to any of the preceding claims, wherein the mesh comprises a support (5) at the circumference of the wall, the support optionally able to cover any space formed between the circumference of the wall and an inner surface of a vessel within which the mesh is arranged.

The mesh according to any of the preceding claims, wherein it comprises a holding structure, formed with a base part and a wall part, wherein elements with an internal mesh configuration forming the base section, and the surrounding wall, are positioned. The mesh according to claim 10, wherein the troughs or gutters are formed by the holding structure.

The mesh according to claim 10 or 1 1 , wherein the holding structure is formed to close any gaps between the surrounding wall and an internal wall of a vessel wherein the mesh is positioned.

The use of at least one mesh according to any of the preceding claims in a liquid/gas-separator or a liquid disperser.

A separator device for separation of liquids dispersed in a fluid stream, comprising a substantially vertical channel and at least one mesh according to any of the preceding claims, wherein the mesh is positioned in the vertical channel, and the channel comprises an inlet for the fluid stream to be separated, a first outlet for the separated liquids, and a second outlet for the separated fluid stream, the mesh is situated above the inlet and the first outlet, and below the second outlet,.

The separator device according to claim 14, wherein the base section of the mesh, or a support formed as a trough at the circumference of the wall, comprises a drainage hole, and wherein said drainage hole is connected to a drainage channel which comprises an outlet below a liquid level in a bottom part of the separator.