Title: Design and optimization of recycle policies for multicomponent azeotropic distillation processes with bifurcation analysis
Abstract: A novel design method for finding cost-optimized recycle policies for multicomponent azeotropic distillation processes is presented. The design task is formulated in form of a nonlinear optimization problem with the aim of minimizing the energy consumption of the process. The minimum energy demand of each column is determined using the rectification body method (RBM). Closure of the mass balance around each unit of the process is enforced by linear constraints. The feasibility of the split in each column with respect to the distillation boundaries is formulated as a nonlinear constraint. This measure of split feasibility is obtained from a bifurcation analysis of the pinch map which is based on reversible distillation theory. The ternary pressure-swing distillation of an ethanol-water mixture using acetone as an entrainer is used as an illustrative example for the optimization and the assessment of split feasibility.