Intensified hybrid reactive-extractive distillation process for the separation of water-containing ternary mixtures

Separation of ternary mixture is a challenging task if multiple azeotropes exist among the components, and special distillation techniques should be adopted. For water-containing ternary mixtures with multiple azeotropes, a dehydrating agent, ethylene oxide (EO), can be used to consume water with the production of ethylene glycol (EG) as the product, which can be utilized as entrainer for separating the remaining two components. In this work, systematic thermodynamic analysis was conducted to screen for the feasible ternary systems. After conducting suggested analysis without needing of rigorous process simulation, tert-butyl alcohol (TBA)/ethanol (EtOH)/water, tetrahydrofuran (THF)/EtOH/water and acetonitrile (ACN)/isopropyl alcohol (IPA)/water mixtures were chosen to be suitable for this application. Within the scope of using dehydrating agent, a process configuration of triple column reactive-extractive distillation (TCRED) is developed for three different ternary systems. Subsequently, an intensified process configuration - double column reactive-extractive distillation (DCRED), which combines both functions of reactive distillation and extractive distillation in a single unit, is constructed to significantly reduce capital cost and energy consumption. With the application of further energy-saving schemes in the systems, total annual cost and total operating cost of the final proposed design flowsheets can be considerably saved compared to respective separation systems recently published in open literature.