Using electrical resistance tomography images to characterize the mixing of micron-sized polymeric particles in a slurry reactor

Abstract: Electrical resistance tomography (ERT) was employed to study the solid–liquid mixing in a slurry reactor equipped with a top-entering axial-flow impeller. The ERT data were used to reconstruct the tomogram using the linear back projection algorithm and calculate the degree of homogeneity. In this study, the effects of the impeller speed (252–400rpm), impeller pumping mode (downward and upward), impeller type (A310, A100, A200, A320, A315, 3AM), impeller off-bottom clearance (T/3.8–T/2.5, where T is the tank diameter), impeller diameter to tank diameter ratio (D/T =0.29–0.47), particle size (5.2–9.1μm), and solids concentration (15–30wt%) on the degree of homogeneity of micron sized latex particles in a slurry reactor were explored. The results showed that the level of homogeneity in a solid–liquid mixing system improved with the increase in impeller speed. However, after achieving the maximum level of homogeneity, any further rise in the impeller speed had a detrimental effect on the level of homogeneity. A310 impeller, with D/T ratio of 0.31, demonstrated the highest level of homogeneity while the upward pumping direction was found to be more efficient than the downward one. In addition, a clearance of T/3 proved to create the highest level of homogeneity. The results also showed that a rise in the size and concentration of particles decreased the level of homogeneity. Thus, 5.2μm latex particles with the concentration of 15wt% demonstrated the highest level of homogeneity. [Copyright &y& Elsevier]