Potential of Combined Macro- and Micro-Scale Tomography to Monitor Multiphase Viscous Fluid Mixing

L Ruffino1, T A York1, R Mann2, G Tiddy2, O Tadthong2, P Bonnet3, B D Grieve3

1 Department of Electrical and Electronic Engineering, UMIST, PO Box 88, Manchester, M60 1QD. Email: R.Mann@umist.ac.uk

2 Department of Chemical Engineering, UMIST, PO Box 88, Manchester, M60 1QD.

3Syngenta Ltd, Process Studies Group, PO Box A38, Huddersfield, HD2 1FF.

ABSTRACT

Many bulk industrial process mixing operations are poorly understood. This is often as a result of insufficient process monitoring, or lack of suitable monitoring methodology. Electrical resistance tomography (ERT) has been demonstrated to have great potential as a method for the 3-D interrogation of mixing and reaction in stirred tank vessels. In this paper, process tomography case studies for two industrial bulk mixing applications are presented. Each case involved the study of a highly viscous opaque mixing system of which very little about bulk mixing was known. The first was a study of the formation of high-value liquid crystal micelle products, the second case an assessment of a food-grade, high viscosity polysaccharide. Tomographic visualisation was carried out in small-scale pilot vessels. The reconstructed images and conductivity measurements obtained during the study indicated that ERT could successfully discriminate between each phase present during mixing, although the existing hardware’s resolution limits prevented the discrimination of specific phase properties. The results of the study are being used to develop a next-generation imaging system based upon 3-D data acquisition from a combination of existing macro-scale ERT methods and newly developed micro-scale ERT methods. This new approach should provide greatly improved industrial end-user batch process control strategies.

Keywords Electrical Resistance Tomography, Liquid Crystal, Mesophase, High Shear Mixing