Droplet coalescence model optimization using a detailed population balance model for RDC extraction column

Single droplet experiments in a small lab scale Rotating Disk Contactor (RDC) for two different liquid–liquid systems were used to evaluate the coalescence parameters necessary for column simulations. Five different coalescence models are studied; the models parameters were obtained by an inverse solution of the population balance model using the extended fixed-pivot technique for the discretization of the droplet internal coordinate. The estimated coalescence parameters by solving the inverse problem were found dependent on the chemical test system. The Coulaloglou and Tavlarides model was found to be the best model to predict the experimental data for both test systems. These parameters were used to study the hydrodynamics and mass transfer behavior of pilot plant RDC extraction column using the simulation tool LLECMOD. This is performed for two different liquid–liquid systems as recommended by the European Federation of Chemical Engineering (EFCE) (butylacetate–acetone–water (b–a–w) and toluene–acetone–water (t–a–w)). The simulated Sauter mean droplet diameter, hold-up values and concentration profiles for organic and aqueous phase were found to be well predicted compared to the experimental data.

► Single and droplet swarm experiments used to investigate coalescence phenomena.
► Inverse population balance problem was used for coalescence parameter estimation.
► Five different theoretical droplet coalescence models are studied and compared.
► Estimated coalescence parameters were found dependent on the chemical test system.
► The retrieved constants were validated by pilot extraction column simulations.