12 - Dust Collectors

Abstract

Publisher Summary Most dust-collection systems are constituted of a pneumatic-conveying system and some device that separates suspended particulate matter from the conveyed airstream. The more common systems use either filter media (for example, fabric bags) or cyclonic separators to separate the particulate matter from air. The principal mechanisms of disposition in dust collectors are gravitational deposition, flow-line interception, inertial deposition, diffusional deposition, and electrostatic deposition. Fabric-filter designs fall into three types, depending on the method of cleaning that is used: shaker cleaned, reverse-flow cleaned, and reverse-pulse cleaned. Fabric-filter systems, commonly called bag-filter or baghouse systems, are dust-collection systems in which dust-laden air is passed through a bag-type filter. The primary measure of baghouse-system performance is its ability to consistently remove dust and other particulate matter from the dirty airstream. Pressure drop and collection efficiency determine the effectiveness of these systems. A cyclone separator is essentially a settling chamber in which gravitational acceleration is replaced by centrifugal acceleration. Dust-laden air or gas enters a cylindrical or conical chamber tangentially at one or more points and leaves through a central opening. The dust particles, by virtue of their inertia, tend to move toward the outside separator wall from which they are led into a receiver. Performance of a cyclone separator is determined by flow pattern, pressure drop, and collection efficiency.