Experimental and Computational Investigation of Vortex Formation in a Single-Stage Rushton Turbine Stirred Tank Reactor Under Standard and Non-Standard Baffle Configurations

An understanding of vortex formation in stirred tank reactors is of great importance, as in some processes, vortices are necessary for a chemical reaction to take place at all or to be accelerated, whilst in other processes, vortex formation is undesirable and can cause high mechanical stresses on the stirrer shaft, sealing and motor drive unit, or may cause undesirable surface aeration or foaming. To gain a better understanding of vortex formation, various baffle systems with different geometries are being experimentally investigated concerning power consumption and the resulting vortices on a single-stage Rushton turbine setup. The shapes of the resulting vortices are described mathematically in terms of vortex depth, width and volume, and the stirring systems prone to vortex formation are simulated using a CFD model based on the Lattice Boltzmann method. The CFD data obtained are compared, validated and verified against the experimental results in order to ultimately be able to fully describe, model and predict vortex formation through simulation. Furthermore, based on the detailed CFD data, vortex formation can be directly correlated with the swirl number, offering a mechanistic characterization method for the vortex shape in various mixing vessel configurations.