Wall Flows in a Cyclone Separator: A Description of Internal Phenomena

Abstract

Liquid-like dense layers of particles are formed on the walls of cyclone separators and on the bottom of pneumatic conveying channels. Such layers exhibit complex wave forms, and in the case of a cyclone arrange themselves in spiral dunes. Since particles centrifuged to the wall must leave a cyclone via wall layer flow, the nature of this flow affects performance, especially under conditions of high loading and maximum separation efficiency. Studies of this fluidized state and conditions for its existence indicate that density is governed by random particle velocities and by prevailing pressure. First-order expressions, describing the mechanics of fluidized layers maintained by a strong shear stress when there is a transverse force on the particles, are developed. A description of associated internal phenomena and a detailed analysis of performance parameters are also presented.