In this paper a generic process model for the simulation of various downstream processes for protein purification is presented. It consists of detailed, dynamic models for ion-exchange membrane adsorbers, ion-exchange and size-exclusion chromatography and ultra-/diafiltration. For the implemented ion-exchange membrane adsorber model, the steric mass action model has been applied. The isotherm parameters have been determined experimentally for bovine serum albumin (BSA) and immunoglobulin G (IgG). The comparison between simulation results of the ion-exchange membrane and experiments for two protein mixtures containing BSA and IgG shows satisfactory agreement. Two case studies based on the purification process of human serum albumin are performed to illustrate the influence of structural changes in the process flowsheet on the process performance. The simulation results show that the replacement of an anion-exchange chromatography column by an anion-exchange membrane adsorber leads to a significant reduction in overall process time at constant yield and purity. The case studies demonstrate the applicability of the generic process model for detailed process analysis.