Simulation of single particle motion along 3-dimensional turbulent flow in air cyclone with blowdown

Abstract

Cyclone separators have been one of the most widely used as equipment for separation or classification of particle from fluid. The improvement of cyclone performance for collecting sub-micron particles can be done by aspirating fluid stream from the upper part of dust hopper. Therefore, the main objectives of this research are to investigate of fluid flow field and particle trajectory within air cyclones and to study the effect of blowdown ratio on the collection efficiency regarding sub-micron particles and pressure drop across cyclones by using Computational Fluid Dynamics (CFD) technique. Therefore, the commercial FLUENT[superscript TM] program is employed to calculate three-dimensional of fluid dynamics and particle motion with turbulent flow in cyclones. It can be found in this research that the results of simulation of collection efficiency and pressure drop are good agreement with experimental data of Dirgo and Leith (1985), and Yoshida (1996). The Reynolds Stress Model (RSM), non-isotropic turbulent viscosity model, is better agreement with experimental results than the Standard k-epsilon and RNG-k-epsilon turbulent model. The simulated result shows that to increase collection efficiency of sub-micron particles can be done by increasing inlet air velocity or increasing ratio of blowdown. It can be found in this simulation that increasing inlet air velocity from 15 m/s to 20 m/s, the collection efficiency of particle with 1.5 micron becomes higher from 6% to 10% and the pressure drop also 80% higher. Alternatively, increasing the ratio of blowdown to 10%, the collection efficiency becomes higher from 6% to 21% and the pressure drop is increased only 10%. Therefore, to aspire air from hopper section provides the better collection efficiency and lower pressure drop than increasing inlet air velocity.