Monday, May 5, 2008
9-10

Towards Optimal Operation of Distillation Column for Bioethanol Production

Tassia Lopes Junqueira, Faculty of Chemical Engineering, State University of Campinas, P.O. 6066, Campinas-SP, 13081-970, Brazil, Rubens Maciel Filho, Department of Chemical Process – School of Chemical Engineering, State University of Campinas, Cidade Universitária, P.O. Box 6066, Campinas, Brazil, and Maria R. Wolf Maciel, School of Chemical Engineering, State University of Campinas, P.O. Box 6066, CEP 13083-970, Campinas-SP, Brazil.

            Bioethanol represents an important option for the exploitation of an alternative source of energy and the reduction of polluting gases. As a means to increase its economic efficiency as fuel, optimization proposals are essential, mainly on ethanol concentration and dehydration, which usually require a significant amount of energy.
            The focus of this work is the separation of a mixture proceeding from the fermentation stage. This mixture is sent to a conventional distillation column in order to concentrate ethanol near the azeotropic value. This column was optimized by minimizing the product loss and the demanded energy.
            A great number of components, like ethanol, water, acetaldehyde and furfural, and the strong interaction between them make the column’s simulation more complex. These components are present in industrial large scale units but rarely are taken into account. Therefore, a deep study about this interaction is indispensable as well as how such components impact the general column behavior including the energy consumption.
            The work was carried out in the Aspen Plus® simulator and comparison with experimental data was considered. An extensive evaluation of the thermodynamic models adequacy was made to represent suitably the separation process units. The results have shown that a significant improvement in terms of energy consumption can be achieved with optimal operation definition and also it is depicted that is important to take into consideration components usually neglected in the separation process synthesis.