Using tomography to examine the distribution of poly-disperse solid particles in Newtonian and non-Newtonian fluids with the coaxial impellers

Abstract

An extensive literature review shows a lack of comprehensive research work regarding the distribution of poly-disperse solids in Newtonian and non-Newtonian fluids. In this investigation, the efficiency of a coaxial reactor (a high rotational speed central axial-flow impeller and a low speed wall-scrapping anchor impeller) in distributing the poly-disperse particles in water (Newtonian) and carboxymethyl cellulose (CMC) solutions (non-Newtonian) was assessed employing a flow-visualization methodology (electrical resistance tomography). The solids hold-up profiles were measured by making use of the tomograms. The critical rotational speed of a central stirrer in achieving the just suspension state for various operating conditions was determined via measuring the particle bed height. The extent of axial distribution of poly-disperse particles was characterized utilizing the data from tomography measurement. The effects of some key variables such as poly-disperse ratio, impeller rotational mode, and CMC loading on the distribution of poly-disperse particles in coaxial agitated systems were extensively analyzed. The capability of the coaxial impellers in distributing the poly-disperse solids in water and CMC solutions was compared to that with a traditional single agitator. Overall, an improved level of distribution of poly-disperse particles in water and CMC solutions was obtained at lower power usage employing the coaxial impellers.