Monday, April 19, 2010
LL Conference Facility (Hilton Clearwater Beach)
Brazil has been producing bioethanol on a large scale basis for more than 30 years by fermentation of sugars obtained from sugarcane, which yields a wine containing 7 – 10 wt% ethanol. In order to be used as a fuel, mixed with gasoline, wine must be dehydrated to at least 99.5 wt% ethanol. Conventional distillation is employed in order to produce hydrous ethanol (about 93 wt% ethanol) and subsequent alternative dehydration processes are required since water and ethanol form an azeotrope with 95.6 wt% ethanol at 1 atm.
Different processes may be used to produce anhydrous ethanol; the most common processes employed in the industry are azeotropic distillation with cyclohexane and extractive distillation with monoethyleneglycol, as well as adsorption onto molecular sieves.
In this work, simulations of the complete separation process, which comprises concentration and dehydration stages, were carried out in Aspen Plus®. For ethanol dehydration, azeotropic and extractive distillation processes were evaluated.
Results showed that concentration step can require from 50 to 80% of the total amount of energy required for the complete separation process, depending upon the dehydration process employed.
Simulation of the azeotropic distillation process revealed to be more complex than extractive distillation, mainly because of the formation of a second liquid phase inside the azeotropic column. In addition, energy requirement for extractive distillation represents about 25% of that necessary in azeotropic distillation.
Different processes may be used to produce anhydrous ethanol; the most common processes employed in the industry are azeotropic distillation with cyclohexane and extractive distillation with monoethyleneglycol, as well as adsorption onto molecular sieves.
In this work, simulations of the complete separation process, which comprises concentration and dehydration stages, were carried out in Aspen Plus®. For ethanol dehydration, azeotropic and extractive distillation processes were evaluated.
Results showed that concentration step can require from 50 to 80% of the total amount of energy required for the complete separation process, depending upon the dehydration process employed.
Simulation of the azeotropic distillation process revealed to be more complex than extractive distillation, mainly because of the formation of a second liquid phase inside the azeotropic column. In addition, energy requirement for extractive distillation represents about 25% of that necessary in azeotropic distillation.