Design and optimization of an ethanol dehydration process using stochastic methods

Due to the increasing demand for renewable fuels that are economically attractive, as well as part of the quest for energy alternatives to replace carbon-based fuels, the purification of ethanol plays a key role. This paper presents the design and optimization of a dehydration process for ethanol, using two separation sequences: a conventional arrangement and an alternative arrangement based on liquid–liquid extraction. Both sequences were optimized using a stochastic global optimization algorithm (differential evolution) implemented in Mathworks Matlab and coupled to rigorous process simulations carried out in Aspen Plus. The economic feasibility of the two configurations was studied by changing the ethanol–water composition in the analyzed feed stream. The results clearly demonstrate that significant savings are possible by extraction when the ethanol content in the feed stream exceeds 10% mol (22 wt%).

► Bioethanol dehydration by a hybrid process: L–L extraction & extractive distillation.
► Process optimization using differential evolution, combining Matlab and Aspen Plus.
► The novel hybrid process for ethanol dehydration presents variable savings in energy.
► Energy savings in the hybrid process depends on the extractant in the extraction column.
► Energy savings in the hybrid process is a function of the ethanol–water feed composition.