Imaging Immiscible Liquid-Liquid Systems by Capacitance Tomography

Abstract

Electrical capacitance tomography offers the opportunity to visualize the contents of a process vessel or pipeline which contains dielectric materials or where the continuous phase is a non-conducting dielectric. This work describes the application of this novel imaging technique to a range of liquid-liquid processes from a laboratory-scale mixing vessel to an industrial-scale liquid-liquid contactor. Single-plane specially-designed sensors containing arrays of either 8 or 12 measurement electrodes, with the same number of driven-guard electrodes, were attached to a bench-scale (diameter—0.15 m) mixer, a bench-scale (diameter—0.10 m) flow column, and a large (diameter—0.6 m) flow column. The capacitance measurements were processed by an image reconstruction algorithm based on linear back-projection to convert the measurements to images of the distribution of dispersed phase across the section of the equipment under investigation. Tomographic images of the distribution of dispersed phase were obtained. These images clearly show the distribution of dispersed phase within the sensing zone of these liquid-liquid systems. The potential application of ECT as a non-intrusive monitor of liquid-liquid systems in industrial-scale contactors is very promising indeed.