| 摘要 |
PURPOSE:To prevent local deterioration of a filter element by a method wherein the mesh size of a catalytic perforated type filter element is changed corresponding to flow velocity distribution of gas and gas passing amount is equalized equvalently over a total flow passage cross area. CONSTITUTION:A filter element 1 provided in a duct 3 has numberless gas passing pores 1a, 1b arranged thereto on a same flat surface thereof and the mesh size of the gas passing pore 1a in a central part thereof is made larger than that of the gas passing pores 1b in a peripheral part thereof. Thereby, inherent characteristics of an axial flow fan 2 wherein flow velocity in a center of a flow passage cross area generated by th axial flow fan 2 is slower than flow velocity in the peripheral part thereof is ensured and flow velocity distribution of a forcedly passed gas is equalized equivalently over total flow passage. |
