Size-resolved particulate matter filtration efficiency of macroporous asymmetric SiC ceramic filters

Abstract

Controlling particulate matter (PM) emissions to the atmosphere in industrial processes is critical for a safe and healthy environment. Because of its high strength and thermal stability, silicon carbide (SiC) is among the best materials for producing hot gas filters to be coupled to sugarcane bagasse-fired boilers in Brazil and India. In this study, we evaluated the performance of asymmetric SiC-based filters of different features for removing fine PM with particle sizes ranging from 90 to 3000 nm. The collection efficiency of the asymmetric filter made of SiC/mullite support with no pore former, porosity of 31–33 %, and permeability of (0.17–0.30) × 10−11 m2 with a coating thickness of 109–138 μm, effective pore size of 19–26 μm, and effective collector diameter of 64–86 μm was higher than 99 % for PM with size greater than 0.60 μm. The SiC formulation with mullite and pore former also presented promising performance. The resulting pressure drop remained within the range reported for commercial hot gas filters. Over 99 % of the mass of soot and fly ash particles generated during sugarcane bagasse combustion exceeds the MPPS range found for filters, which was between 0.16 and 0.36 μm. Therefore, the SiC asymmetric filters presenting mullite in their formulation are anticipated to meet current international emission standards.