Chemical Engineering & Technology, Vol.24, No.3, 287-292, 2001
Combined wettable/non-wettable filter for mist purification
Previous studies by Agranovski and Braddock  show that wettable filters are very efficient at collecting small liquid aerosols. However, a major problem associated with wettable filters is the breakthrough process associated with the destruction of film covering the fibres, and the removal of relatively large droplets by the carrier gas passing through the rear surface of the filter. A non-wettable filter is relatively efficient at collecting large droplets and discarding them down its front face . These two types of filters can be combined in layers to make use of these distinctive properties. The best arrangement is where the carrier gas passes first through the wettable filter, and then through the non-wettable filter. Where there is a contact between the two filters, interface effects assist the filtration and filter system drainage. The filtration mechanisms are enhanced when the filter box is tilted so that gravity partially opposes the drag forces on the liquid in the filter. In the current paper, the results of experimental analysis of combined filtration systems are presented, and further steps towards industrial design are discussed.