Energy-efficient and cost-effective alternative separation techniques for 2-methoxyethanol-toluene azeotropic mixture: Design and control studies

The separation of 2-Methoxyethanol-toluene azeotropic mixture has high practical significance in both industry and the laboratory because of their multipurpose solvating properties. However, both 2ME and toluene have adverse effects on human and animal health; therefore, researchers have become interested in their separation. A significant amount of 2-methoxyethanol-toluene forming a minimum-boiling azeotrope is discharged by the electrochemical industry. The presence of this azeotrope renders separation a challenging task. Separation techniques, namely pressure swing distillation (PSD) and azeotropic distillation (AD), have not yet been explored. In this study, these separation techniques are evaluated economically and dynamically using a well-known commercial simulator Aspen Plus (R). This study includes the development of process schematics for these alternative separation processes and economic analysis involving total annual cost (TAC) calculations. It is concluded that the heat-integrated PSD technique leads to 21.35% savings in TAC compared to previously reported techniques. Furthermore, a decentralized plant-wide control structure for a suitable separation technique is also developed and tested for +/- 10% throughput manipulations in fresh feed flow rate and +/- 5% disturbances in feed composition. This study will significantly help the process engineers overcome the challenges of handling the electrochemical industry's hazardous effluent in environmentally and economically ways.