Dynamic Modeling of Filter-Aid Filtration Including Surface- and Depth-Filtration Effects

A new mechanistic model for filter-aid filtration with incompressible cakes is presented. Surface- and depth-filtration effects are considered based on a continuum mechanics approach. This leads to a moving boundary problem with sharp moving fronts. Proper mathematical and numerical methods for its solution are identified which allow fully transient simulations concerning all process variables and parameters. All relevant physical phenomena known from experimental studies are captured by the model, some of them for the first time. In two case studies, the effects of changing the filter-aid particle diameter at a discrete time point and continuously varying the amount of filter aid with time are considered. Significant influences on the separation efficiency, the local deposit profile within the filter cake, and the overall pressure drop are found.