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Reducing the energy demand of corn-based fuel ethanol through salt extractive distillation enabled by electrodialysis



The thermal energy demand for producing fuel ethanol from the fermentation broth of a contemporary corn-to-fuel ethanol plant in the U.S. is largely satisfied by combustion of fossil fuels, which impacts the possible economical and environmental advantages of bioethanol over fossil fuels. To reduce the thermal energy demand for producing fuel ethanol, a process integrating salt extractive distillation—enabled by a new scheme of electrodialysis and spray drying for salt recovery—in the water-ethanol separation train of a contemporary corn-to-fuel ethanol plant is investigated. Process simulation using Aspen Plus® 2006.5, with the electrolyte nonrandom two liquid Redlich-Kwong property method to model the vapor liquid equilibrium of the water-ethanol-salt system, was carried out. The integrated salt extractive distillation process may provide a thermal energy savings of about 30%, when compared with the contemporary process for separating fuel ethanol from the beer column distillate. © 2011 American Institute of Chemical Engineers AIChE J, 2012

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