Design and Control of an Alternative Bioethanol Purification Process via Reactive Distillation from Fermentation Broth

Bioethanol is considered one of the most promising renewable energy sources. However, since the concentration of bioethanol obtained from fermentation process is very low and there is a minimum boiling point azeotrope between water and ethanol, the well-known separation techniques result in an increase in the capital and operating costs of bioethanol separation processes. Thus, alternative process configurations to purify bioethanol is in the focus of attention of industry. In this study, an enhanced process configuration is economically evaluated and dynamically controlled based on the idea of consuming the water by reacting it with ethylene oxide to produce ethylene glycol, thus obtaining pure bioethanol by breaking the water-ethanol azeotrope without adding any separation agent. Design results show that this configuration is an attractive option because it outperforms the base-case design given in the literature by a 19.3% decrease in total annual cost (TAC). In addition, it generates an economic income by producing ethylene glycol as an added-value byproduct. Dynamic simulations of the enhanced process configuration show that the control structure design including inferential temperature loops ensures a stable regulatory control.