Droplet population balance modelling—hydrodynamics and mass transfer

The hydrodynamic and mass transfer behavior of a rotating disc contactor extraction (RDC) column based on a bivariate population balance model is investigated using the generalized fixed-pivot technique for the discretization of droplet internal coordinate. Single-droplet and swarm-droplet studies in small lab-scale devices were used to evaluate breakage and coalescence parameters necessary for column simulations. The breakage probability of single droplets was measured and a new correlation was developed, which also takes viscosity effects into account. Coalescence probability studies resulted in chemical system dependent parameters, which were obtained by an inverse solution of a simplified balance model. In a final study, the hydrodynamic and mass transfer behavior of pilot plant RDC columns have been simulated based on the parameter set derived from the lab-scale units. The simulated mean Sauter diameter, hold-up values and concentration profiles were found to be well predicted at different operating conditions. The relative error for the simulated mean Sauter diameters is about 15%, for the hold-up about 20% and for the concentration profiles about 20%.