Fibrous bed filtration is an efficient method with low pressure drop for removing fine dust from gas flows. And in filtration industry, we often meet for cartridge filtration or filter bag applications.

 In particular, metallic materials are of interest in the filtration of fine particulate materials exhasuted from high-temperature industrial boilers and automobiles burning liquid diesel. The porous beds composed of metal fibers are very open and quite resistant against hot fluids or sudden fluctuation of the flow.

 Although conventional flat ceramic or metallic plates are dominated mainly by surface filtration, the bed of thin metal fibers has combined dust trapping mechanisms by the filter depth and surface. Because the thin metal fibers do not consist of any systematic matrix, and open paths are connected in three dimensions in all directions, the [DELTA]P entailed by particle clogging does not increase as high as surface filters.

In particular, even very tiny particles much smaller than the inner open channels can be trapped by electrostatic forces, as well as diffusion in special cases depending on materials or operation condition. This leads to the effective collection of fine dust. Researchers for the fibrous filters have attempted to find the mechanism of fibrous filters.

Recent development of novel metal alloys and process technology provides various choices for the porous filter beds.

 Fecralloy composed of Fe, Cr, and Al is excellent in mechanical stability and chemical and thermal resistivity.

 Fecralloy fiber was used as a packing material for a porous filter bed in this work. This filter medium was examined with comparison to a thin ceramic filter for the collection of polydispersed dust particles. The present metal fiber bed was also applied to a diesel soot trap.

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