1 - Gas filtration

Abstract

Filtration of particles from the gas stream is one of the main classes of particulate air cleaning devices. The filter medium is the most essential component of every cleaning device based on filtration principle. The effectiveness of a cleaning device is determined by the type of filter media. A wide range of different filter media can be utilized, including fibrous filter media, packed bed, and fabrics. Fibrous filter medium can be defined as a permeable material composed of sparsely distributed fibers upon which particles are deposited by the different filtration mechanisms. A conceptual way to think of a fibrous filter medium is as a significant number of layers, each with randomly populated fibers resulting in an open three-dimensional network. The primary task of a fibrous filter medium is to cause a separation of particulates from the gas stream with the minimum energy consumption. Fibrous filter media can be characterized by many different chemical and mechanical properties. It can be considered as a system of randomly oriented fibers with a preferred orientation across the direction of flow, with packing density in the range of 0.01–0.15 (porosity 85%–99%) and fiber diameter 0.1–50μm.