Liquid mixing dynamics in slurry stirred tanks based on electrical resistance tomography

In this work, liquid mixing in a solid-liquid baffled stirred tank is investigated experimentally by Electrical Resistance Tomography (ERT). Since the technique works non-intrusively in opaque systems, the limitations of the most widespread experimental methods for the mixing time estimations are overcame. Whole-field data on the homogenization dynamics are collected with liquid only and with a mass ratio of suspended solid to liquid equal to 0.43. The liquid mixing time, which is often adopted as a measure of the intensity of mixing in turbulent stirred tanks, leads to quantitatively assess the significant difference in the scalar mixing process in the agitated slurry with respect to the single-phase systems. Besides, novel definitions for intensity, scale and rate of change of mixing are proposed. With respect to the conventional mixing time estimation, the parameters extracted from the raw ERT data provide a deeper insight into the evaluation of the scalar mixing dynamics in stirred tanks.