MODUL TIL ANVENDELSE VED ULTRAFILTRERING SAMT FREMGANGSMAADE TIL FREMSTILLING AF ET ROERFORMET ORGAN ANVENDT I MODULET

1468928 Ultrafiltration UNION CARBIDE CORP 9 May 1974 [10 May 1973] 20524/ 74 Headings B1D and B1X An ultrafiltration unit 10 comprises a housing enclosing parallel porous tubes 32 which separate an inlet space having inlet 26 and outlet 30 from a filtrate outlet space with an outlet 28, tubes 32 being made of carbon, alumina or aluminosilicate having pores in the 0.1 to 2.0 micron dia. range which add up to a pore volume of at least 12%, the upstream surfaces of the tubes having a metal oxide coating 0.01 to 10 microns thick and comprising aggregated particles less than 5 microns into the tube walls. Preferably at least 50% of pores have diameters between 0.10 and 0.50 microns. As shown filtration is outwards through the tube walls, but inward flow filtration is possible. Various metal oxides (e.g. alumina and zirconia) are listed for the coating, which may comprise a first layer of particles 0.1 to 1 microns dia. and a top layer of particles below 0.1 microns. The coating is applied to the tubes by circulating an acidified aqueous suspension of coating material therethrough, and remains thereon even when tubes are washed and steam sterilised. Figs. 3 to 6 (not shown) illustrate alternative ways of connecting the tubes to tube plates 34, 36. Fig. 3 involves metal O-rings clamped around the ends of tube 32 by a second plate (48) and cap (50). In Figs. 4 to 6 rubber gaskets enclose the tube and are retained in recessed portions of the tube plate apertures, 25 to 1000 tubes may be located in one PVC or stainless steel housing. Tubes may be of various cross-sections including star-shaped and triangular. The unit may operate in series or parallel with other units or alone in a circuit illustrated in Fig. 1 (not shown) wherein feed liquid is recycled to pass repeatedly from inlet 26 to outlet 30 and thereby becomes concentrated in suspended solids, dissolved large molecules or oil which cannot penetrate the tube coating. The axial flow through the tubes is at turbulent velocity to prevent accumulation of solids thereon. Particular applications include removing oil and dirt from aqueous detergent solutions to enable their reuse in car washes, laundries or washing machine metal parts, separating polyvinyl alcohol from textile sizing solutions, recovering paint from wash water following electro-painting, concentrating spent grain liquors in brewing, clarifying vinegar, recovering protein molecules from cheese whey, clarifying sea water prior to desalination by rev