Role of Porosity in Dust Cleaning of Silicon Carbide Ceramic Filters.

Abstract

Silicon carbide ceramic filters consisting of highly porous support and filtration layer were fabricated by cold isostatic pressing. The porosities of the supports were varied near the percolation threshold, 28.7, 33.7 and 35.8%. The silicon carbide layer with a finer pore size was coated on the supports to collect dust particles. The pressure drop (ΔP) was measured at various face velocities, dust loadings, and operation times. The separation efficiency was calculated by measuring the dust concentrations at the inlet and outlet of the filter vessel, and the cleaning efficiency was calculated by comparing the pressure drops before and after back-pulse cleaning. The results indicate that higher porosity of the filter support is favorable for preventing an increase of pressure drop and for improving cleaning efficiency. As the porosity in the silicon carbide filter support increased from 28.7% to 35.8%, the pressure drop decreased by as much as 30%. Most of dust particles were collected by the finer pores in the coating layer with efficiencies >99.9%. Additionally, better cleaning efficiency was obtained at higher porosity. The values of flexural strengths of the filter supports were over 20MPa even though a lower value was found at high porosity.