THEORETICAL INVESTIGATIONS INTO THE COMPRESSION OF DUST CAKES DEPOSITED ON FILTER MEDIA

Periodically regenerable cake-forming surface filters are widely used in particulate control technology. The particles collected on the filt er medium surface build up a so-called 'dust cake'. The operational ch aracteristics of such filter apparatus are strongly influenced by the structure of the dust cake formed. The structure itself depends (among other factors) on the particle size distribution, particle charge, ad hesive and cohesive properties, and on the pressure drop. The dust cak e mass and therefore its flow resistance with respect to pressure drop increase with filtration time. This rise in pressure drop is in many cases not linear. Local compressions of the dust cake are considered t o be responsible for the progressive increase of pressure loss with ti me. This theory was confirmed by quantitative analyses of dust cake st ructures in an earlier paper. The present paper reports on a simulatio n program based on a simple model, by which local transient porosities inside the dust cake and the pressure drop as a function of time can be calculated.