Determination of the mixing rate of a high velocity feed stream in agitated vessels

In semi-batch or continuously stirred reactors, often a feed containing one or more reactants has to be mixed with the contents of the vessel. For fas t competitive or consecutive reactions the mixing rate of the feed stream w ith the vessel contents has a large influence on the product quality. The m ixing rate is often controlled by the turbulent dispersion process. Therefo re, it has been suggested in the literature to keep the turbulent dispersio n time constant upon scale-up to obtain a constant product quality. In this study, based on a combination of a theoretical model, Planar Laser Induced Fluorescence experiments and Laser Doppler Velocimetry experiments, the tu rbulent dispersion coefficient is determined. This has been done for the ca se that a feed stream is mixed in a stirred vessel by a combination of feed stream and stirrer generated turbulence. The turbulent dispersion coeffici ent is used to derive an equation for the turbulent dispersion time as func tion of several design and process variables.