Simulating Stirred Tank Reactor Characteristics with a Lattice Boltzmann CFD Code

Although mixing in stirred tanks is common in the chemical and process industry, it is complex and not fully understood. In recent years, computational fluid dynamics (CFD) simulations with large eddy simulation turbulence models have become an important modeling tool. In this study, its current state for applicability to stirred tanks was evaluated. First, the power characteristics of different impellers were simulated and compared with experimental data. Second, Rushton and pitched blade turbines were validated in terms of the local velocity components, dissipation rates, and the trailing vortex. Finally, mixing times for different viscosity ratios were obtained from the CFD results and compared with a literature study. Hydrodynamics can be well predicted. However, mixing times for viscosity ratios larger than 1:100 are error-prone. There is a need for reliable models of mixing in stirred tanks, which is widely used in the chemical and process industry but complex and not fully understood. A lattice Boltzmann code with a large eddy simulation turbulence model was used to determine power numbers and mixing times in stirred tanks with different impellers. Local velocity fields and dissipation rates were compared with literature data. image