Three-Way Coupling Simulation of a Gas-Liquid Stirred Tank using a Multi-Compartment Population Balance Model

Abstract

Modelling of gas-liquid stirred tanks is very challenging due to the presence of strong bubble-liquid interactions. Depending upon the needs and desired accuracy, the simulation may be performed by considering one-way, two-way, three-way or four-way coupling between the primary and secondary phase. Accuracy of the prediction on the two-phase flow generally increases as the details of phase interactions increase but at the expense of higher computational cost. This study deals with two-way and three-way coupling of gas-liquid flow in stirred tanks which were then compared with results via four-way coupling. Population balance model (PBM) based on quadrature method of moments (QMOM) was implemented in a multi-compartment model of an aerated stirred tank to predict local bubble size. The multi-compartment model is regarded as three-way coupling because the local turbulent dissipation rates and flow rates were obtained from a two-way computational fluid dynamics (CFD) simulation. The predicted two-phase flows and local bubble size showed good agreement with experimental data.

Design of Extractive Reaction Systems

“…Due to the large number of CFD cells, algorithms aggregate cells into compartments based on chemical and/or physical criteria defining the similarity of cells. [82] Compartment modeling approaches for multiphase fluid systems have been published for reactive bubble columns [88], airlift reactors [89], and gas-liquid CSTRs [90]. More recently, Weber established a liquid-liquid extraction model for a Kühni column [91] and multiphase loop-reactor [92], incorporating a detailed PBM approach for the disperse phase.…”

“…Compartment modeling approaches for multiphase fluid systems have been published for reactive bubble columns , airlift reactors , and gas‐liquid CSTRs . More recently, Weber established a liquid‐liquid extraction model for a Kühni column and multiphase loop‐reactor , incorporating a detailed PBM approach for the disperse phase.…”

Simulation of Polymer Reactors Using the Compartment Modeling Approach

“…In compartment models, as a combined approach between CFD models and axial dispersion models, model complexity is reduced on macro scale by describing the reactor in uniform compartments, which enables the implementation of complex kinetics on micro scale. This compartment modeling approach has been proved suitable in different applications 32–47. Among others, successful applications to bioreactors,32–34 bubble columns,35,36 and loop reactors37 have been reported by now.…”

“…Among others, successful applications to bioreactors,32–34 bubble columns,35,36 and loop reactors37 have been reported by now. Additionally, compartment models have been used to simulate, for example, gas–liquid stirred tank reactors 38–41. In the field of polymerization reactors compartment models are applied to homo polymerizations in autoclaves42,43 and to emulsion polymerizations in semi batch stirred tanks 44–47.…”

“…The determination of compartments in the reported applications is mostly performed based on either simulated velocity fields as for bioreactors, loop reactors, and bubble columns32,33,35–37 or energy dissipation rate, for example in stirred tank models 38–41,46,47. Others used (tracer) concentration and temperature gradients to determine compartments 34,42,44,45.…”