GB2127318A

GB2127318A - Improvements relating to apparatus for separating two immiscible liquids

Info

Publication number: GB2127318A
Application number: GB08226621A
Authority: GB
Inventors: Denis John Majer
Original assignee: Individual
Current assignee: Individual
Priority date: 1982-09-17
Filing date: 1982-09-17
Publication date: 1984-04-11
Also published as: GB2127318B

Abstract

A separator screen assembly (5) is provided for separation of two immiscible liquids. A support frame (32) retains a coalescer screen 11 of non-woven continuously bonded fibers held against a support grid 15. A similar separator screen 12 is held against a support grid 16. A drainage gap 10 between the two screens 11 and 12 can be varied as required by altering the angle, height and distance of the screen 12 from the fixed screen 11 depending upon the characteristics of the liquids being separated. As an emulsion passes through the screen 11 drops of the discontinuous phase liquid are separated out and are trapped in the space 10 by the screen 12 and will be drained through the gap 31. <IMAGE>

Description

SPECIFICATION Improvements relating to apparatus for separating two immiscible liquids This invention relates to apparatus which is able to separate the discontinuous phase liquid suspended in a continuous phase liquid. Atypical situation where such apparatus may be used is in connection with steel or paper mills, or for the purification of turbine lubricating oil used in steam turbines of electrical power generating stations. Equally, however, the apparatus may be required to separate oil as the discontinuous phase from water and there are many other liquid mixture systems where such separation may be required.

It is an object of this invention to provide a form of separator which can function with a variety of ratios of liquids and which will separate the discontinuous phase liquid from a continuous phase liquid in which it is suspended so as to create a separate discrete volume of the discontinuous phase liquid which can readily be removed.

According to one aspect of this invention there is provided a separator screen assembly for separating two immiscible liquids comprising a support frame supporting, in sequence, a coalescer screen with a supporting grid and a separator screen with a supporting grid, the separator screen defining a drainage gap with the support frame for the drainage of discontinuous phase liquid separated out by the assembly, and adjustment means for moving one screen with respect to the other to vary the spacing of a passageway between the two screens through which the separated out liquid will flow to the drainage gap.

With such an assembly the coalescer screen effectively breaks down the emulsion to create relatively large droplets of the separated liquid which are then trapped in the passageway between the two screens and tend to coalesce as they are carried towards the drainage gap, through which the separated liquid will be removed.

Ideally the adjustment means is designed to enable the width and/or the degree of taper at the passageway between the two screens to be varied.

In a preferred embodiment the adjustment means will comprise channel members retaining one of the screens and having portions movable within slots, covered by asymmetric blanking washers, in side walls of the support frame. Preferably, the assembly will additionally include an adjuster for altering the vertical position of the separator screen to modify the size of the drainage gap. Advantageously the adjustment means and the adjuster will be linked together. Thus the adjustment means could be linked to the adjuster by a pivoted linkage. The adjuster could be a screwthreaded rod retained against axial movement and carrying a screwthreaded boss on which is mounted the separator screen.

From a further aspect the invention provides a separator system for separating two immiscible liquids comprising, in sequence, an emulsion break screen assembly and a separator screen assembly as hereinbefore defined, with a space between the two assemblies. Such a system will carry out a two-stage separation of the discontinuous phase liquid from the continuous phase liquid. In a preferred arrangement the emulsion break screen assembly comprises a support frame supporting, in sequence, first and second emulsion break screens, each with a supporting grid, a space being formed between the two screens allowing passage of separated discontinuous phase liquid to a drain point out of the support frame.

It is preferred that the two grids of the emulsion break screen assembly should face one another between the two screens. In the preferred arrangement the two grids may be in the form of lattices having only point contact with one another. Thus the one grid could provide ribs extending in one direction whilst the other grid defined ribs crossing in another direction. Spacers may be provided to create a required spacing between the two screens of the emulsion break screen assembly.

In the preferred embodiments the screens of all the screens assemblies will have pore sizes of between thirty and one hundred microns. It may be of advantage to provide that the screen at the upstream end of each support frame is of finer mesh size than the other screen. The screens may be formed from any suitable material which will not be attacked by the liquids passing through the separator and a preferred material is non-woven continuous bonded fibres of polyolefinic material. The supporting grids may be formed from thermoplastic mesh, in which case each screen could be thermally bonded to its respective supporting grid if the screen is formed from a compatible material. As an alternative the supporting grids could be formed from non-corrosive metal mesh.

Ideally perforated support plates will be provided at the outer faces of each screen assembly. If these perforations are angled with respect to the upstream to downstream direction of each screen assembly, the discontinuous phase liquid condensed out can be directed in a preferential path towards the drainage gap.

The invention also extends to a separator tank for separating two immiscible liquids passing therethrough and provided with a separator of the invention as hereinbefore defined positioned across the flowpath through the separator tank and including means for removal of the separated liquid at a drain point.

Such a separator tank may be provided with a drain sump with a valved outlet (preferably automatic) or a surface skimmer for removal of the separated liquid, and a sight glass could also be provided.

Under normal operating conditions it would not be regarded as practical to position the separators horizontally and it is in fact preferred that each screen assembly should be disposed vertically or be angled so that the drainage outlet of the screen assembly is positioned downstream.

The separator tank may include a polypropylene strainer positioned upstream of the separators for removal of coarse particulate matter. Equally, filter bags may be positioned downstream of the separators for filtering out of fine particulate matter.

The invention further extends to a method of separating the discontinuous phase from the continuous phase of two immiscible liquids wherein the liquid to be subjected to the separation treatment is passed through a separator of this invention as hereinbefore defined and the separated liquid is drawn off.

The invention may be performed in various ways and preferred embodiments thereof will now be described with reference to the accompanying drawings, in which: Figure 1 illustrates a complete separator system employing two forms of separator in a separator tank; Figure 2 shows a form of coalescing separator of the invention set within a frame and as used in the system of Figure 1; Figure 3 is a partial view in cross-section on the line Ill-Ill of Figure 2; Figure 4 is a section through an emulsion break separator as used in the system of Figure 1; and Figures Sand 6 show features of supporting grids of the separator of Figure 4.

Figure 1 illustrates a separator system within a separator tank 1 for coalesing and separating water as a discontinuous phase from oil as the continuous phase. The mixed liquid enters through an inlet 2 and is caused to pass through a polypropylene strainer 3 which removes large particulate matter carried by the oil. The liquid then passes through an emulsion break separator screen assembly 4 (of the form as illustrated in Figure 4) which is effective to separate emulsified water from the oil which will then be coalesced into larger water droplets within a coalescing separator screen assembly 5 (of the form as illustrated in Figure 2) so that the water will then flow as a continuous phase from the bottom of the separator 5 down the sloping base wall 6 of the separating tank 1 to a drain sump 7 from which it may be removed through a water dump valve (not shown).The dried oil then passes through filter bags 8 which will prevent the passage of any fine particulate matter present in the oil, and leaves through the outlet 9. If the separator tank is to be used, for example, for removing oil as the discontinuous phase from water as the continuous phase then the oil separated by the separator 5 would rise to the top of the tank and float on the surface of the water. In this instance the drain holes would be formed at the top of the separator 5 (or its surrounding frame) and any tapering of the passageway 10 between the two screens 11 and 12 of the separator 5 would create a widening of the passageway in the upward direction (as opposed to widening in the downward direction as shown in Figure 1).The separated oil floating on the water surface can be removed by a skimmer 13 of any suitable design, the top of the tank being enclosed by a cover plate sloping towards the skimmer 13.

The coalescing separator screen assembly 5 is illustrated in more detail in Figures 2 and 3. In this assembly there are provided respective coalescer and separator screens 11 and 12, for the separation of the discontinuous phase from a liquid passing through in the direction of the arrow 14. Each of the screens 11 and 12 is formed from a polyolefinic material in the form of non-woven continuous bonded fibres and is supported by plastics mesh grids 15 and 16. The respective screen and grid assemblies 11,15 and 12,16 are held between outer support plates 17 formed from aluminium alloy with downwardly directed pierced openings. A distinct passageway 10 is formed between the two screens 11 and 12 which widens in the direction towards the drainage end 18 of the separator.Variation of the width of the gap 18 and the extent of widening is enabled by means of movable side channel members 19, within which is mounted the screen 12 together with its support grid 16 and the outer support plates 17 as shown also by Figure 3. Each channel member 19 is mounted on a side wall 20 of the assembly by clamp screws 21 passing through slots 22 in the side wail 20 and held by asymmetric blanking washers 23 and nuts 24. The sandwich of the separator screen 12, grid 16 and support plates 17 is mounted on a support rod 25 by a nut and bolt assembly 26, 27 the rod 25 being pivotally connected to a nut 28 which is carried by a screw-threaded rod 29 with a winged head 30. Thus the screen 12 may be moved with the channel members 19 to any desired position or angle within the limits determined by the slots 22 and held there by tightening up the nuts 24.

Furthermore rotation of the rod 29 by means of the winged head 30 acts on the rod 25 to cause the height of the screen 12 to be raised or lowered within the channel members, so as to vary the gap 31 between the screen 12 and the base of the frame 32 of the assembly 5, as required. The sandwich of the coalescer screen 11, grid 15 and support plates 17 is held over the opening 33 into the frame 5 by bolts 34.

The emulsion break separator screen assembly 4 is illustrated in Figures 4 to 6 in greater detail. This assembly basically comprises a first emulsion break screen 35, a first supporting grid 36, a second supporting grid 37 and a second emulsion break screen 38 acting as a trap for coalesced liquid droplets created by the first screen 35 as an emulsified liquid is passed through the assembly 4 in the direction of the arrow 39. Again the screens 35 and 38 are formed from a polyolefinic material, and the grids 36 and 37 from plastics mesh. Outer support plates 40 are also provided, formed from aluminium alloy with downwardly directed pierced openings.

As shown in Figure 5, each supporting grid 36 is formed by ribs 41, the ribs of the two grids 36 and 37 passing in opposite directions, as shown in Figure 6, so that, if they touch, they will have only point contact. This permits a free passage of the separated liquid through the spaces formed between adjacent pairs of ribs on one or other of the grids 36 and 37. A clamping screw 42 mounted in a support frame 43 of the assembly 4 grips together the sandwich of the grids and screens via a clamping strip 44. If additional spacing between the grids 36 and 37 is required then spacers 45 may be inserted, the thickness of the spacers determining the size of the gap between the grids. Thus a passage of any desired width can be achieved between the two screens 35 and 38 for the drainage of the discontinuous phase liquid.The gross separated liquid will flow, between the two screens 35 and 38, towards the drain outlet 7 or 13 at either the top or bottom of the separator tank 1, depending upon the relative specific gravity of the respective liquids. Liquid draining at the base of the tank 1 will pass the assembly 5 through a passageway 46 formed in the base thereof (Figure 2), whilst separated liquid draining at the top of the tank 1 can be allowed to float over the top of the assembly 5 or through a passageway formed through the assem buy 5.

Since the screens 11 and 12, and the screens 35 and 38 and their respective supporting grids, are quite independent in the separator assemblies 4 and 5 described, the width of the passageways betwee them can be varied at will (in the manner described).

Furthermore it is possible to remove and replace one screen at a time of each separator assembly, if a screen should become clogged or if a screen of finer or coarser mesh is required for a particular purpose.

The coalescing and separating function may require a much finer mesh screen 11 to break up a stable emulsion at the upstream end of the separator assembly 5, whilst a coarse downstream screen 12 will permit free passage of the continuous phase. If necessary several separator assemblies may be positioned in series in the separator tank 1 (or for example in a rectangular conduit through which the liquid will pass).

In the separator system illustrated in Figure 1 the first screen assembly 4 is effective to remove larger particles of discontinuous phase liquid the smaller particles in emulsified form passing through in suspension in the continuous phase liquid to the secondary screen assembly 5. The amount of work to be performed on the liquid to cause the discontinuous phase liquid to be condensed out will depend both on the rate of flow of the liquid through the separator tank 1 and the width and degree of taper of the passageway between the two screens 11 and 12 of the separator 5 which can of course be varied by means of the adjuster mechanisms provided. For example, if a very wet oil was to be treated a large gap 10 between the screens 11 and 12 would be needed together with a fairly obvious taper to create a downward thrust on the water droplets condensed out.The louvred support screens 17 also create a downward thrust on the liquid passing through the separator 5. For an oil having a minor water content, a very narrow passageway 10 would be required so as to create maximum work on the liquid.

As a modification, in the screen assembly 4, the spacer 45 could be replaced by another emulsion break screen 35 to increase the effectiveness of the separator 4.

CLAIMS (Filed on 18.8.83.) 1. A separator screen assembly for separating two immiscible liquids comprising a support frame supporting, in sequence, a coalescer screen with a supporting grid and a separator screen with a supporting grid, the separator screen defining a drainage gap with the support frame for the drainage of discontinuous phase liquid separated out by the assembly, and adjustment means for moving one screen with respect to the other to vary the spacing of a passageway between the two screens through which the separated out liquid will flow to the drainage gap.

2. An assembly according to claim 1, wherein the adjustment means is designed to enable the width and/or the degree of taper at the passageway between the two screens to be varied.

3. An assembly according to claim 2, wherein the adjustment means comprises channel members retaining one of the screens and having portions movable within slots, covered by asymmetrical blanking washers, in side walls of the support frame.

4. An assembly according to any one of claims 1 to 3, including an adusterfor altering the vertical position of the separator screen to modify the size of the drainage gap.

5. An assembly according to claim 4, wherein the adjustment means and the adjuster are linked together.

6. An assembly according to claims 3 and 5, wherein the adjustment means is linked to the adjuster by a pivoted linkage.

7. An assembly according to any one of claims 4 to 6, wherein the adjuster is a screwthreaded rod retained against axial movement and carrying a screwthreaded boss on which is mounted the separator screen.

8. A separator system for separating two immiscible liquids comprising, in sequence, an emulsion break screen assembly and a separator screen assembly as claimed in any one of claims 1 to 7, with a space between the two assemblies.

9. A separator system according to claim 8, wherein the emulsion break screen assembly comprises a support frame supporting, in sequence, first and second emulsion break screens, each with a supporting grid, a space being formed between the two screens allowing passage of separated discontinuous phase liquid to a drain point out of the support frame.

10. A separator according to claim 9, wherein the two grids of the emulsion break screen assembly face one another between the two screens.

11. A separator according to claim 10, wherein the two grids are in the form of lattices having only point contact with one another.

12. A separator according to claim 11, wherein one grid provides ribs extending in one direction and the other grid defines ribs crossing in another direction.

13. A separator according to any one of claims 9 to 12, wherein spacing between the two screens of the emulsion break screen assembly is provided by spacers.

14. A separator according to any one of claims 1 to 13, wherein the screens have pore sizes of between thirty and one hundred microns.

15. A separator according to any one of claims 1 to 14, wherein the screen at the upstream end of each support frame is of finer mesh size than the other screen.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. drainage of the discontinuous phase liquid. The gross separated liquid will flow, between the two screens 35 and 38, towards the drain outlet 7 or 13 at either the top or bottom of the separator tank 1, depending upon the relative specific gravity of the respective liquids. Liquid draining at the base of the tank 1 will pass the assembly 5 through a passageway 46 formed in the base thereof (Figure 2), whilst separated liquid draining at the top of the tank 1 can be allowed to float over the top of the assembly 5 or through a passageway formed through the assem buy 5. Since the screens 11 and 12, and the screens 35 and 38 and their respective supporting grids, are quite independent in the separator assemblies 4 and 5 described, the width of the passageways betwee them can be varied at will (in the manner described). Furthermore it is possible to remove and replace one screen at a time of each separator assembly, if a screen should become clogged or if a screen of finer or coarser mesh is required for a particular purpose. The coalescing and separating function may require a much finer mesh screen 11 to break up a stable emulsion at the upstream end of the separator assembly 5, whilst a coarse downstream screen 12 will permit free passage of the continuous phase. If necessary several separator assemblies may be positioned in series in the separator tank 1 (or for example in a rectangular conduit through which the liquid will pass). In the separator system illustrated in Figure 1 the first screen assembly 4 is effective to remove larger particles of discontinuous phase liquid the smaller particles in emulsified form passing through in suspension in the continuous phase liquid to the secondary screen assembly 5. The amount of work to be performed on the liquid to cause the discontinuous phase liquid to be condensed out will depend both on the rate of flow of the liquid through the separator tank 1 and the width and degree of taper of the passageway between the two screens 11 and 12 of the separator 5 which can of course be varied by means of the adjuster mechanisms provided. For example, if a very wet oil was to be treated a large gap 10 between the screens 11 and 12 would be needed together with a fairly obvious taper to create a downward thrust on the water droplets condensed out.The louvred support screens 17 also create a downward thrust on the liquid passing through the separator 5. For an oil having a minor water content, a very narrow passageway 10 would be required so as to create maximum work on the liquid. As a modification, in the screen assembly 4, the spacer 45 could be replaced by another emulsion break screen 35 to increase the effectiveness of the separator 4. CLAIMS (Filed on 18.8.83.)

1. A separator screen assembly for separating two immiscible liquids comprising a support frame supporting, in sequence, a coalescer screen with a supporting grid and a separator screen with a supporting grid, the separator screen defining a drainage gap with the support frame for the drainage of discontinuous phase liquid separated out by the assembly, and adjustment means for moving one screen with respect to the other to vary the spacing of a passageway between the two screens through which the separated out liquid will flow to the drainage gap.

16. A separator according to any one of claims 1

to 15, wherein the screens are formed from nonwoven continuous bonded fibres of polyolefiric material.

17. A separator according to any one of claims 1 to 16, wherein the supporting grids are formed from thermoplastic mesh.

18. A separator according to any one of claims 1 to 17, wherein each screen is held firmly at the periphery of its respective supporting grid.

19. A separator according to any one of claims 1 to 18, wherein perforated support plates are provided at the outerfaces of each screen assembly.

20. A separator according to claim 19, wherein the perforations are angled with respect to the upstream to downstream direction of each screen assembly towards the drainage gap.

21. A separator tank for separating two immiscible liquids passing therethrough and provided with a separator as defined in any one of claims 1 to 20 positioned across the flowpath through the separator tank, and including means for removal of the separated liquid at a drain point.

22. A separator tank according to claim 21, wherein a drain sump with a valved outlet or a surface skimmer is provided for removal of the separated liquids.

23. A separator tank according to claim 21 or claim 22, wherein each screen assembly is disposed vertically or is angled so that the drainage outlet of the screen assembly is positioned downstream.

24. A separator tank according to any one of claims 21 to 23, including a polypropylene strainer positioned upstream of the separator for removal of coarse particulate matter.

25. A separator tank according to any one of claims 21 to 24, including filter bags positioned downstream of the separators for final filtering out of fine particulate matter.

26. A separator as defined in claim 1 or claim 8 and substantially as herein described with reference to the accompanying drawings.

27. A method of separating the discontinuous phase from the continuous phase of two immiscible liquids wherein the liquid to be subjected to the separation treatment is passed through a separator of this invention as claimed in any one of claims 1 to 26 and the separated liquid is drawn off.