Design and control of an ideal reactive divided-wall distillation process

Reactive distillation and divided-wall distillation are two promising technologies achieving substantial economical benefits from process intensification. In this study, a novel reactive divided-wall distillation process, procuring technical advantages from both reactive distillation and divided-wall distillation, is designed with different degrees of thermal coupling to achieve possible energy saving for an ideal quaternary reaction system with the least favorable relative volatility ranking under excess-reactant design. Simulation results demonstrate that reactive divided-wall distillation can provide better energy efficiency than reactive distillation without thermal coupling. Energy efficiency increases with the degree of thermal coupling. Proper selection and pairing of controlled and manipulated variables chosen for three control objectives are determined by using steady-state analysis. Temperature control in the reactive distillation column is used to maintain reactant inventory in the process. Product purities are maintained by the temperature control loops in the divided-wall column. Stage temperatures that have modest sensitivity to manipulated variables and have little variations with respect to throughput rate changes are selected as controlled variables. Dynamic tests show that the proposed control scheme can maintain high product purity and stoichiometric balance between the reactant feeds for throughput rate changes. Copyright © 2011 Curtin University of Technology and John Wiley & Sons, Ltd.