Two identical 10-mm hydrocyclone connected in series for improving particle separation efficiency is studied using two particulate samples. The operating variable effects, such as feed rate, split ratio and pressure drop through hydrocyclones on the separation efficiency, energy loss and outlet particle concentration are thoroughly discussed. Some empirical operating equations correlated to dimensionless groups, e.g., Reynolds number, Euler number, Stokes number and spilt ratio, are proposed that can be employed for evaluating the partial separation efficiency and the hydrocyclone installation effectiveness. The partial separation efficiency of various particulate samples under different operating conditions can be expressed as a unique power-type general Stokes number and split ratio equations. When two hydrocyclones are installed in series, the d50 value decreases significantly, however, no evident difference can be found for the d100 cut-size. To connect a second hydrocyclone in series and to operate at a high split ratio in the first hydrocyclone are the optimal conditions from the particle separation efficiency, energy saving and outlet clarity viewpoint. However, the particle classification sharpness cannot be improved by connecting two hydrocyclones in series due to the fish-hook effect.
Journal of Taiwan Institute of Chemical Engineers 40(3), pp.313-319