A more appropriate way to optimize the hybrid reactive-extractive distillation system

Existing studies on reactive-extractive distillation (RED) commonly misapply optimization variables by including reaction stages. Given the uncatalyzed nature of ethylene oxide (EO) hydration in RED, where it naturally occurs throughout the column, a more appropriate strategy is to optimize only the total stages, allowing the reactive stage to align accordingly. However, previous attempts to implement this approach faced challenges. Here we introduce an algorithm addressing the variable overlap issue in optimizing RED, exemplified in two case studies. In Case 1, we explored a distinct scenario where the original process designated a specific reaction zone. Adjustments were made to ensure the reaction occurred throughout the entire column but it leads to a 13 % total annual cost (TAC) increase compared to the base case. In Case 2, optimization was applied to a system where reaction were distributed throughout the column without prior optimization, yielding a marginal 3.87 % reduction in the TAC.