Changes in the performances of filter media during clogging and cleaning cycles

The performance of two filter media used in industrial air cleaning were studied both in the initial state (new filter) and after a number of collection and pulse pressure cleaning cycles. The main difference between them is that one has anti-clogging properties and the other does not. The test aerosol is composed of alumina particles with a median volumetric diameter of 2.6 microm (MMAD=4.8 microm) generated at a concentration of 700 mg x m(-3). Filtration took place at a velocity of 2 cm x s(-1). Two parameters, namely pressure drop and efficiency, were monitored according to the collection and cleaning cycles. The comparison of the filtration efficiency of the two media and that of the corresponding industrial dust separator at the end of the cycles showed a close agreement. The separation efficiency calculated with a new medium (corresponding to initial switch-on of the installation) was low and increased very quickly during the cycles. Finally, a phenomenological model was developed to represent the increase in pressure drop of a filter medium after cleaning and was found to be in close agreement with the experimental values.