Simulation of aromatics extraction with an ionic liquid in a pilot-plant Kuhni extractor based on single-drop experiments

Pilot-plant experiments in a Kühni extractor for the extraction of toluene from a heptane+toluene mixture by means of the ionic liquid [3-mebupy][DCA] were performed. Previous work (Meindersma et al., 2010, 2012) has shown that [3-mebupy][DCA] is a promising solvent for the extraction of aromatic substances such as toluene. An alternative approach to performing time and material consuming pilot-plant experiments is modelling with the drop population-balance model ReDrop. Models in the ReDrop program accounting for different phenomena, such as drop sedimentation, drop breakage and coalescence as well as mass transfer, contain liquid-liquid system specific parameters that are fitted to lab-scale experiments with single drops. A single-drop sedimentation experiment with heptane (c)+toluene+[3-mebupy][DCA] (d) was performed and the parameters of the sedimentation model fitted to the experimental data. Models accounting for the hindrance of drop sedimentation due to column internals and models for drop breakage were taken from the literature. On this basis, the Kühni extractor was then simulated with ReDrop. Hydrodynamic parameters such as hold-up and Sauter mean diameter are in good agreement with the experimental data. Also the mass-transfer performance of the [3-mebupy][DCA] in combination with the Kühni extractor was modeled with good accuracy. It was shown that the ReDrop concept is a promising alternative to pilot-plant experiments in terms of need of materials and time to evaluate new ILs for their usability in extraction columns.