Micromixing Characteristics Of Non-Newtonian Fluid In A Stirred Tank

The influence of viscosity on the micromixing of Non-Newtonian fluid was investigated by using parallel competing reactions.The experiments were carried out in a stirred tank of 0.476m diameter with a three narrow blade hydrofoil CBY impeller and Rushton turbine. The improved parallel competing reactions, the precipitation reaction of NaOH and CuSO4 and alkaline ester hydrolysis, were used as working reactions to investigate the micromixing in non-Newtonian fluid of Hydroxyethyl cellulose (HEC) water solutions of 0.1 %-0.5 %. The effects of feed time, impeller speed, feed position, viscosity and non-Newtonian factors on the yields of by-product (XQ) were systematically studied based on the linear relationship of copper ion absorbency and concentration. The experiments results show that XQ strongly depends on the viscosity of the liquid. Xq increases greatly as the viscosity of HEC increases. The Reynolds number is not the suitable scales-up rule for the viscous liquid. Under the same shaft power input and feeding at the impeller region, XQ is smaller for the higher power number impeller.A simplified micromixing model, the Engulfment model (E-model), was modified to predict the product distribution. Reasonable agreement can be found between the results predicted by the E-model and the experimental data. The results are of importance to the design and scale-up...