Comprehensive Optimization Approach for Inherently Safer Design of Sustainable Distillation Systems in Zeotropic and Hazardous Multicomponent Separations

In the petroleum and chemical industries, distillation is widely applied in the separation and purification of hazardous chemicals, with its energy consumption accounting for more than 50% of the total energy consumption. The inherently safer design of distillation systems is the fundamental guarantee for safe, steady, long-term, and efficient operation. Therefore, this work proposed a multiobjective optimization approach for the inherently safer development of distillation systems through the introduction of the mass-energy stage as a basic unit and the inherent safety index (ISI) for process safety evaluation to assess potential alternatives. State-space network was employed to construct the solution space, while Dow’s F&EI and CO2 emissions were adopted to quantify the safety and sustainability performance, respectively. Two illustrative examples were carried out, where the optimal configuration could reduce F&EI by 5.50%, with a 2.06% increase in CO2 emissions and total annualized cost (TAC) for the ternary aromatic separation while the optimal configuration could reduce inventory by 77.81% with TAC and CO2 emissions increased by 20.34 and 26.23% for ternary paraffin separation, respectively. The results of the two illustrative examples indicate that through the redistribution of vapor–liquid phase streams among mass-energy stages, a significant improvement in process safety can be achieved with little price in CO2 emissions.