Maximizing energy savings attainable by dynamic intensification of binary distillation

Dynamic intensification of distillation columns has shown significant promise in achieving energy savings with minimal investment in new equipment. Conceptually, it entails making a desired product as a blend of two auxiliary products (one with higher purity, the other with lower purity, but both having lower energy consumption). Practically, dynamic intensification means periodically switching between two operating states corresponding to the aforementioned products. Past work has relied on ad-hoc choices of auxiliary products. In this paper, we introduce a new optimization framework for selecting auxiliary products for dynamic intensification. An extensive case study concerning the separation of a methanol/propanol mixture is then presented. Furthermore, we show that optimizing the choice of auxiliary products can lead to significant energy savings (more than 3.6% compared to a column operated at steady state) derived from dynamic intensification.