Safety and control analysis of hybrid liquid-liquid extraction and divided wall column for biobutanol purification

Butanol is getting attention among the possible biofuels as an alternative to bioethanol. Compared to bioethanol, biobutanol shows less miscibility with water, less flammability and corrosivity, and it has the advantage of being able to directly replace gasoline in the car engines without any modifications. However, the production cost from the Acetone-Butanol-Ethanol (ABE) fermentation process remains high, mainly due to the low yield of butanol. The conventional recovery of butanol by distillation is a process of high energy consumption that has greatly restricted its industrial production. In this work different hybrid configurations, based on liquid-liquid extraction and dividing wall columns were examined. Sustainability was analysed based on green metrics, inherent security, and control properties through open and closed-loop policy using PI controllers. The results indicate that as long as the process is highly intensified, the sustainability and the inherent safety are improved but not necessarily the control properties. The best alternative was selected as a compromise between contrasting objective functions.