Micromixing In A Stirred Tank

Mechanically agitated reactor are widely used in many industrial processes. Micromixing refers to the process of material homogenization from Kolmogorov scale to the molecular scale after turbulent diffusion. Micromixing has a great influence on the product distribution of complicated and fast reaction. Micromixing has been studied intensively in the last decades, but most of the researches have been carried out in small scale reactors. It is difficult to investigate the effect of tank geometry on micromixng in such small scale reactors. Single Rushton turbine was used in most researches so far. Little attention has been paid to the characteristics of micromixing in tank with multiple-impellers or hydrofoil impellers, which are commonly used in industries. A pair of competitive parallel reactions were used to investigate the micromixing in a stirred tank of 0.476m diameter with single and multiple impellers, gas chromatography was used to analyze the product distribution. Narrow blade hydrofoil CBY impeller, hollow blade disk turbine HD-6 and combinations of these two impellers were used in the experiments. The effects of feed time, rotation speed, feed location and agitator types on product distributions were systematically studied. A simplified engulfment model (E-model) was applied to calculate the product distribution of parallel reactions, agreement can be found between the results predicted by E-model and the experimental data. The results are of importance to the design and scale-up of industry stirred reactors with fast complex reactions.