SOLID CONCENTRATION DISTRIBUTION IN SLURRY STIRRED TANKS

The knowledge of solids concentration distribution is central for predicting the performance of various industrial processes dealing with solid-liquid suspensions. Although dense systems are often tackled in practice, relatively limited information have been collected so far on apparatuses with solid loadings over 20 weight %, mainly due to the fact that most experimental techniques are applicable to dilute suspensions only. The aim of this work is to investigate the solid distribution in dense solid-liquid stirred tanks. A fully baffled cylindrical vessel stirred by a Lightnin A310 impeller under different operating conditions is considered and the experimental data are collected by means of Electrical Resistance Tomography (ERT). The solid-liquid system consists of de-mineralized water as the continuous phase and glass beads (sieved between 300-420 µm) as the disperse phase. The solid concentration distribution is assessed by varying the solid loading and the impeller speed. The results provide a further demonstration of the suitability of ERT for the study of dense solid-liquid stirred systems. The distribution of the solids over the whole reactor and a novel approach for the solid mixing evaluation are presented.