Currently, process intensification using dividing-wall columns (DWCs) is one of the most promising alternatives for reducing the costs of the distillation process. However, for extractive distillation, there are still questions regarding whether the DWC is a more economical option than the conventional sequence (CS). Normally, extractive DWCs are simulated with two thermally coupled columns (TCSs), and their designs are usually obtained by setting the TCSs in different ways that do not necessarily constitute an optimum design. Thus, this work proposes a systematic procedure based on stage equilibrium for obtaining an optimized DWC configuration, in terms of operability and design. A strict comparison between the DWC configuration and the CS (also optimized) was performed, and the best results in terms of the total annual cost (TAC) were obtained for columns with a distinct number of stages in each section of the wall; however, these columns did not outperform the optimized conventional systems.

No abstract

Distillation is one of the oldest and most important separation processes used in the chemical and petrochemical industries. On the other hand, it is a process the thermodynamic efficiency of which is very low, and therefore reducing the consumption of energy is one of the targets of research studies on distillation. This article arose from seeking to reduce energy consumption in a distillation train of 1,2-dichloroethane (ethylene dichloride-EDC) of a commercial plant producing vinyl monochloride (VMC), which involves an azeotropic distillation column. The reduction in the reboiler heat duty caused significant changes in concentration and temperature profiles throughout the column due to the formation of two liquid phases. The results show that, although very small in percentage terms (less than 2.5%), the appearance of the 2 nd liquid phase causes significant changes in the operation of the column and the separation achieved.