Optimization of distillation configurations for multicomponent-product distillations

Several optimization formulations exist in the literature for optimizing distillation configurations for unicomponent-product distillations (UPD), i.e., distillations where each product consists of only a single component. However, many separations either desire product streams composed of multiple components based on their end-use property requirements or tolerate such multicomponent products in exchange for savings in the objective, e.g., reductions in energy consumption. In this work, we propose an easy-to-use transformation that allows any UPD configuration to be used for multicomponent-product distillations (MPD) while controlling the composition of the product. This transformation is used in our optimization model to minimize the heat duty of MPD configurations derived from UPD for zeotropic separations. We apply this formulation to identify and rank energy-efficient configurations for an industrial crude petroleum case study, and show that the ordering of configurations on an energy efficiency basis is quite different using the MPD model compared to the UPD model.