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

Abstract

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

Extractive distillation with ionic liquids: A review

“…The use of solid salts to obtain anhydrous alcohols dates back to the patents by Adolf Gorhan, which were the basis for the HIAG process . Solid salts (e.g., CaCl 2 , KAc, NaAc, and NaCl) are good entrainers when added into the reflux of an extractive distillation column (EDC) . Conversely, liquid solvents are easily entrained into the top product of the distillation column due to their volatility, whereas solid salts may erode the tray or packings, and the dissolution, reuse, and transport of solid salts are significant issues in industrial operation.…”

Bioethanol recovery and purification using extractive dividing-wall column and pressure swing adsorption: An economic comparison after heat integration and optimization

“…high enough salt concentration at the top of the column which results in a reasonable number of stages required to achieve the desired separation) and no salt precipitation would occur in the column [19]. It has been shown that calcium chloride provides the best salting out effect on ethanol, and extractive distillation using calcium chloride as the separating agent has lower energy requirement than that using ethylene glycol as well as azeotropic distillation using benzene [20,21]. It was also found that extractive distillation with calcium chloride consumes almost the same energy as membrane pervaporation [10].…”

A new process for fuel ethanol dehydration based on modeling the phase equilibria of the anhydrous MgCl2 + ethanol + water system

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