The experimental study of the flow within a transparent hydrocyclone with a vortex finder attachment

Abstract

The experimental studies of the flow behaviour within 50-mm hydrocyclones with and without a vortex finder attachment (Fin) have been performed. The flow characteristics within both hydrocyclones were observed visually and recorded both photographically and on video as the hydrocyclones are made of a transparent material. The development of the double-helical flow was observed; also the shape and diameter of the air-core have been examined for different values of operating pressure drop. It was found that the air-core is unstable and its size, shape and position are unfixed because of the instability of the gasliquid interface. The results also showed that the air core is related to the shape of the underflow discharge and is a function of the pressure drop. A regular spray discharge from the spigot was observed. The roping discharge was observed when an extension pipe was connected to the underflow outlet. An increase in pressure drop leads to an increase in air-core diameter and the angle of the underflow profile. However, the relationships between these three parameters are non-linear. The knowledge of the size and location of the air-core relative to the operating pressure drop can assist in the validation of computational fluid dynamics (CFD) simulation work. The separation performance of these two transparent hydrocyclones for a CaCO3 in water system has been investigated. In this study, the results showed that a fin-type vortex finder attachment could not increase the sharpness of separation but it could help in the thickening process. It can be seen that the separation performance does not depend only on the geometry and operating conditions, but also on slurry concentration and particle size distribution. The concentration of the feed slurry and the operating pressure drop strongly affect the sharpness of separation.