Simulation of particulate processes with population balances has matured to the point where complex production processes can be modelled quite accurately. We give two examples of what is possible by utilising standard tools and sophisticated models. Combining models from different backgrounds leads to more than the mere sum of the separate results. This is exemplified by discussing a carbon black reactor simulation and the whole process chain for spray drying granulation. In both cases the results are mostly, qualitative. nevertheless the tendencies of the real process (stability, interdependence on operating conditions) can be predicted with some accuracy. With this knowledge the process engineer has a tool for designing new and optimising existing reactors, in order to obtain tailor-made products. (c) 2006 Elsevier B.V. All rights reserved.