Design and control of an energy-efficient intensified process for biobutanol purification from isopropanol-butanol-ethanol (IBE) fermentation broth

Biobutanol is one of the most preferable alternative fuels because of its superior fuel properties compared to other biofuels. In recent years, biobutanol production through isopropanol (IPA)-butanol-ethanol (IBE) fermentation has gotten more attention than acetone-butanol-ethanol (ABE) fermentation. However, the downstream separation process of this production is very energy intensive due to the several azeotropes. In this study, an energy-efficient process configuration including a reactive distillation column is proposed to break the azeotropes. In the proposed configuration, water present in the azeotropic mixture is consumed by a water-ethylene oxide (EO) reaction. Steady-state results show that the proposed configuration provides a 30% decrease in energy consumption and a 26.7% reduction in total annual cost (TAC) compared to the configurations in the literature, while ethylene glycol is obtained as a by-product besides the biobutanol of 99.5% purity. Additionally, two plantwide control structures are developed, and the dynamic controllability of the configuration is examined. Dynamic results illustrate that a robust control is provided with the proposed control structure 2 (CS2) when it is tested against disturbances in feed flowrate and feed composition.