GB657601A - Improvements relating to the separation of immiscible liquids - Google Patents

Abstract

<PICT:0657601/III/1> <PICT:0657601/III/2> <PICT:0657601/III/3> A mixture of liquids in which a first liquid, e.g. water, is present in fine particles in a second liquid, e.g. oil, immiscible therewith is separated by passing the mixture through a body of porous material to effect mechanical coalescing of the particles to form coalesced bodies of the first liquid and thereafter forcing the mixture against a porous wall member which is impervious to the first liquid and pervious to the second liquid so as to cause the second liquid to flow through and so as to effect final or residual coalescing of the particles of the first liquid into coalesced bodies which are held back by the porous wall and separate from the second liquid on account of difference in specific weights of the two liquids. The mixture from the body of porous material is passed to the porous wall member in an elongated path in which separation of the coalesced bodies takes place, resulting in a reduction of the amount of the first liquid coalesced at the body of porous material to be brought into contact with the porous wall member. As shown in Fig. 1, the mixture of liquids, e.g. an emulsion of water in hydrocarbon liquid, is introduced under pressure through pipe 23 into the annular space 28 between the cylindrical member 14 and an inner cylindrical member 25, of which a portion of the cylindrical wall is constituted by a mat 30 formed of a hydrophilic material such as closely packed glass fibres preferentially water wetted in the presence of the hydrocarbon liquid. When fine particles of hydrocarbon liquid are dispersed in water, the glass fibre material is treated to render it hydrophobic or water repellant, e.g. with silicones or with an alkyl, aryl, aralkyl or alkaryl silicon halide such as methyl silicon chloride in vapour form. The mixture is forced through the mat 30 and the fine particles of the dispersed phase are caused to coalesce forming larger drops or bodies as they pass with the continuous phase liquid through the mat 30 which also functions as a filter, into the annular space between the member 25 including mat 30 and the sleeve 33, then reversing direction of flow into and along the interior of sleeve 33 to the container 11. During reversal and the passage of the mixture along this path the coalesced bodies of the dispersed phase can separate out by gravity and are thereby prevented from acting against the porous walls 40 in the unit 35. This unit 35 comprises a plurality of membranes 40, Fig. 2, e.g. of glass fibres which are phillic to the continuous phase liquid, spaced by annular members 38, 39 to form chambers to alternate ones of which the liquid mixture is introduced through elongated slots 46 in the spacers 39. Spacers 38 and 39 are provided with inwardly projecting apertured bosses 47, 49 which, on assembly, together with apertures in the membranes 40 form a manifold 51. The bosses 47 of spacers 38 are recessed or slotted at 48 so that the continuous phase liquid flowing through membranes 40 into the chambers formed by spacers 38 passes through the slots 48 and into manifold 51 which discharges into chamber 53, Fig. 1, and leaves the apparatus through pipe 55. The dispersed phase particles coalesce at the surface of the membranes 40 but do not pass through and separate out rising or falling through the mixture according to the specific weights of the liquid phases. When the dispersed phase is the heavier liquid, the coalesced bodies settle downwardly and are collected in the vessels 58 and 59, the coalesced bodies formed at the membranes 40 passing through the slots 46 in the spacers 39. If the dispersed phase is the lighter liquid, the apparatus, Fig. 1, is inverted, the outlet 55 being stopped up and the continuous phase being then discharged through outlet 56. The dipersed phase separating out in the space 62 between the cylinder 25 and sleeve 33 can discharge into container 11 through the aperture 64 and some liquid through the aperture 63. Air vents 19 allow air to escape from the apparatus on starting it into operation. The contents of the vessels 58 and 59 are removed through the drain plugs 60, 61 intermittently or they may be removed automatically and continuously by the device shown in Fig. 6. Each vessel 58, 59 is formed with a narrow cylindrical part 66 provided interiorily with an upstanding porous member 70, e.g. of ceramic material, of which the upper closed end is approximately at the same level as a removable priming plug 71. A tube 74 extending upwardly terminates at a region adjacent the closed end of member 70. When the ceramic member is once wetted and the pores thereof filled with water, the water collecting in the part 66 seeps into the porous tube 70 and is drained away through tube 74. Specification 628,464 is referred to.