Filtering properties of twin-layer sintered filters

Abstract

1. At equal filter thickness, twin-layer sintered filters from nonspherical powder have a much superior combination of filtration qualities (permeability and purification fineness) compared with filters made entirely from the same powder. 2. The dependence of permeability on resistance for twin-layer filters obeys Darcy's law within the limits investigated; for short filtration periods, permeability and purification fineness are the same irrespective of which of the two layers faces the oncoming fluid stream. 3. It is shown that the service life (period of operation before clogging) of twin-layer filters is longer when the filters are placed so that their coarse-fraction powder layer faces the fluid stream; filters arranged during operation with their fine-fraction powder layer against the fluid stream were found to exhibit better regeneration characteristics. 4. It is shown that filters from nonspherical powders can very effectively be regenerated by ultrasonic treatment, but not by the method of counter-blowing (at pressure drops of up to 1.5 MN/m2). 5. For a given filtration fineness, a twin-layer filter has a much longer service life (to clogging) than a filter made from powder of one fraction.