Energy-efficient extractive distillation combined with heat-integrated and intermediate reboilers for separating acetonitrile/isopropanol/water mixture

Abstract A conventional triple-column extractive distillation is researched for the separation of acetonitrile/isopropanol/water mixture with ethylene glycol (EG) as entrainer. In this article, the pressure-relative volatility curve is investigated to find the suitable pressure of column. To achieve the further energy saving, three heat-integrated schemes and two heat-integrated combined with intermediate reboilers schemes are researched based on the conventional extractive distillation. Both two heat integration with intermediate reboilers schemes shown the better performance than other schemes since the further analysis of the energy, exergy, economic and environment (4E) were investigated. For the most energy saving design, PHI-IHI2, it has 48.50% energy-saving, 70.73% exergy efficiency enhanced, 36.24% reduction in total annual cost (TAC) and 48.55% reduction in gas emissions with the comparison of the conventional extractive distillation (CED) process. The result shows the extractive distillation combined with heat-integrated and intermediate reboilers presented great energy-efficient, economy saving and environment friendly for separating acetonitrile/isopropanol/water mixture.