CFD basierte Kompartimentmodellierung für gerührte Flüssig-Flüssig Extraktionskolonnen

  • CFD based compartment-model for stirred liquid-liquid extraction columns

Weber, Benedikt; Jupke, Andreas (Thesis advisor); Pfennig, Andreas (Thesis advisor)

Aachen : RWTH Aachen University (2021)
Book, Dissertation / PhD Thesis

In: Aachener Verfahrenstechnik series AVT. FVT - fluid process engineering 2 (2021)
Page(s)/Article-Nr.: 1 Online-Ressource : Illustrationen, Diagramme

Dissertation, Rheinisch-Westfälische Technische Hochschule Aachen, 2021

Abstract

Stirred liquid-liquid extraction columns are common unit operations used for the separation in chemical industry. For a model based design of liquid-liquid extraction columns drop movement, coalescence, breakage and mass transfer have to be calculated. Models with PBE (Population Balance Equation) are usually applied to describe the drop property distribution either in a one-dimensional (ReDrop) or three-dimensional simulation domain via CFD-PBE-simulations.However, one-dimensional models cannot be applied for various column designs. CFDPBE-simulations require high computational effort. Therefore, a CFD based compartmentmodel was developed. The design dependent velocity profile is approximated with a single phase CFD-simulation calculating the continuous phase. The dispresed phase is neglected to reduce the computational effort. The single phase velocity profile is then applied in the compartment-model to simulate the convection of the continuous phase, drop movement, coalescence, breakage and mass transfer between the phases.The sensitivity of the simulation parameters was investigated in detail. Solver for the calculation of the drop movement in the compartment-model are compared to solver implemented in CFD. The best solver was identified. Additionally, the influence of the simulation time-step-size on the calculation of the drop-trajectory was evaluated. Furthermore, the domain of the simulation parameters scaling factor and grid resolution were determined.The compartment-model was applied for the calculation of a broad data set of experimental column experiments. Two extraction systems with different drop coalescence and breakage behavior were tested as well as various column loads and stirrer speeds. The comparison between simulation and experiments shows a good simulation accuracy. Following, the simulation results of the compartment-model were compared to simulation results of a one-dimensional model (ReDrop) showing the potential of both simulation tools.Therefore, an innovative compartment-model for mutliphase devices was developed. The applicability of the CFD based compartment model was shown at the example of a stirred liquid-liquid extraction column in comparison to column experiments.

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