Authors: J. Gradl and W. Peukert
Affilation: Friedrich-Alexander university of Erlangen-Nuremberg, Germany
Pages: 305 - 308
Keywords: precipitation, mixing, population balance equation, CFD
Precipitation depends on competing kinetics of various interacting parallel and subsequent steps. These are mixing, chemical reactions, nucleation, growth, aggregation and stabilization. The coupling of all subprocesses is the key for predicting the PSD. In this work the influence of the flow field conditions in a mixer on the precipitation process is investigated experimentally as well as numerically. It can be shown that with increasing power input the particle size decreases up to a minimum size. The modeling of the polydisperse particulate process is based on the numerical solution of a one-dimensional population balance equation (PBE). In this work, different approaches are applied to consider the influence of the fluid dynamics. First a global approach is used assuming plug-flow through the mixer and that mixing is totally micromixing-controlled. Therefore another approach was applied calculating a full flow profile by direct numerical simulation (DNS). Lagrangian Particle Tracking couples the flow field simulation with the micromixing model and the kinetics of the solid formation. Due to this approach one resulting PSD can be determined for every path by solving the PBE. By averaging a stochastically sufficient number of paths, it is possible to predict quantitatively the measured PSDs for different process parameters.