The fermentation of grains to make ethanol typically results in mixtures of about 10 wt% ethanol in water. Concentrating the ethanol through distillation is energy intensive. It has been suggested that extraction of the ethanol with CO2 may reduce energy costs and decrease the net pollution from the process due to the reduced demand for fossil fuel. In this project conventional distillation is compared with CO2 extraction. CO2 is not able to break the azeotrope so both the conventional distillation and CO2 extraction would have to be followed by an azeotropic distillation to produce fuel grade ethanol, which is the use of ethanol with the highest growth potential. Therefore, this project involves two alternative processes for the concentration of ethanol from 10% up to the azeotrope at about 95%, followed by a common azeotropic distillation.
This process would be an interesting one-semester design project. Material available on this project includes a project report, PFDs and economic comparisons of the two processes. Instructors can contact Professor Brennecke for this information.
