Process Control for Isopropanol-Water Separation via Azeotropic Distillation with Dividing Wall

Heterogeneous azeotropic distillation is one of many method for breaking azeotrope. Azeotropic distillation is an energy intensive process, with high operating cost. Development of process intensification results in dividing wall column for combining two sequential distillation column into one column. Application of dividing wall column for azeotropic distillation is therefore a prospective process. Process control for azeotropic distillation with dividing wall column is studied to determine its controllability and feasibility for industrial applications. Systems studied in this paper includes isopropanol-water mixture with cyclohexane as entrainer. Product composition, as control objective, is controlled via tray temperature control, with reboiler duty and liquid split ratio as manipulated variables. Internal Model Control (IMC) and Ziegler-Nichols tuning method are also studied and compared. Simulation results with ASPEN Plus Dynamic shows that IMC and Ziegler-Nichols method are equally effective in achieving good process control. However, Ziegler-Nichols is concluded to be simpler for practical application, if compared to IMC.