Abstract
The removal of dust from a filter surface usually involves rapid motion which induces a cleaning force at the dust/surface boundary. In traditional long bag filters large amplitude movement is necessary to generate adequate forces and such motion often results in poor cleaning,premature bag wear and filter blinding. The flat geometry inclined filter was conceived to utilise the enhanced movement propogation of planar surfaces and to maximise the use of the available ground area. A detailed theoretical and pracical examination of the operation and cleaning of such filters has shown that the concept and practicality are in close agreement. The research has indicated that the removal of filter cakes involves inducing cake removal forces in excess of the adhesion forces of the cake/membrane combination. For inclined filters the removal of a cake also involves the transportation of material to the edge of the filter surface, hence combining cleaning and discharge. The filter material is not excessively flexed as a pre-requisite of cake removal and hence membrane wear is low. No general optimum frequency or amplitude can be identified for cake removal and transport because vibration characteristics depend on the size and construction of the filter elements. For a particular construction the optimum frequency was found to to be the resonant frequency of the filter element suspension. The removal of cake was shown to depend upon the product of the cake areal mass and acceleration at each point on the filtration surface (cake removal stress). The concept of vibration transmission and cake removal have been used in a computer model in which the cake and filter medium resistances are combined using a series/parallel concept.