Development of a post cyclone to improve the efficiency of reverse flow cyclones

An auxiliary device named "Post Cyclone" (PoC) was developed to reduce the emission of fines from the exhaust of reverse now cyclones. The PoC makes use of the strong swirl of the gas as it exits through the vortex finder of a cyclone to capture certain fraction of the escaping particles. In its basic configuration, PoC consists of two annular shells placed vertically on the exit of a conventional cyclone. The separation of dust in PoC occurs primarily due to the centrifuging out of the particles in tangential velocity field. In addition to centrifugation, other mechanisms such as flocculation or agglomeration, turbulent dispersion, and particle bouncing may influence the actual collection of the particles in PoC. The relative importance of these mechanisms will depend on PoC geometry, inlet velocity and inlet dust concentration. In order to achieve an optimum design of the PoC for an existing cyclone, the effects of process variables need to be investigated in great detail. This work presents some of the results of the experiments conducted with two different combinations of cyclone and PoC under a range of process variables. In addition, results of modeling of the PoC using computational fluid dynamics (CFD) are also presented. (C) 2000 Elsevier Science S.A. All rights reserved.