CFD based compartment-model for a multiphase loop-reactor

Abstract

In multiphase devices, fluid dynamics have a high impact on concentration profiles and mass transfer between the phases and therefore influence efficiency. Standard models often assume ideally mixed conditions or plug flow. The application of such models for multiphase devices with complex flow patterns causes inaccuracies, if the flow deviates from ideally mixed or plug flow conditions. Therefore, for a precise model based design and operation parameter determination of devices with complex flow patterns, the local fluid dynamics should be considered. CFD simulations for multiphase systems including mass transfer, population balance equations for coalescence and breakage as well as reactions are still time consuming. Thus, we developed a compartment-model based on prior calculated CFD flow-data. In the CFD simulations, the time consuming population balance equations for coalescence and breakage, mass transfer and reactions are neglected. These phenomena are considered in the compartment-model. Thereby we reduce the overall computing time.

This paper presents the CFD based compartment-model applied on a loop-reactor. First, a three-phase CFD model of the developed multiphase loop-reactor is introduced. Following, the paper presents the compartment-model and the application of a time-driven constant-number Monte-Carlo approach to solve population balances. Finally, the compartment-model is applied to the liquid-liquid extraction part of the loop-reactor calculating the drop size distribution and mass transfer based on previously calculated CFD data.