Energy Impact of the Feed Composition to the Dehydration Column in the Production of Bioethanol

Energy Impact of the Feed Composition to the Dehydration Column in the Production of Bioethanol

Hern√°ndez, M. R., Universidad Nacional de Tucuman
Colombo, M., Universidad Nacional de Tucuman
Gatica, J. E., Cleveland State University

The high price and the environmental harmfulness of petroleum fuels have highlighted the need for alternative energy sources, being bioethanol one of the most important source. Bioethanol is a co-product of high profitability and great opportunities for development, its use as biofuel improves the quality of gasoline in an environmentally friendly level.

In 2006, Argentina sanctioned Law 26.093 of Promotion of Biofuels, setting a minimum percentage of 5% of ethanol in gasoline. In April 2016, the mandatory percentage of bioethanol in gasoline was increased to 12% by volume, in the framework of Laws 26,093 and 26,334 for the Regulation and Promotion of Biofuel Production and according to the consolidation of Belgrano Plan. These regulations triggered a significant increase in the production of bioethanol in the province of Tucuman.

The bioethanol production process in Argentina is mainly from molasses fermentation and / or sugar cane juice. The mixture of alcohol and water produced by simple distillation, enters a subsequent separation process for dehydration purposes. Through distillation conventional methods, it is only possible to obtain ethanol concentrations close to 89% mole fraction. Therefore, as the anhydrous ethanol production processes are now a priority environmental, technological and economic; energy efficient separation methods that break the azeotrope, such as extractive distillation are needed.

This study examines the steps involved in simple distillation and the following dehydration step using glycerol as an extractive agent. For this, an extractive column leading anhydrous ethanol and a distillation column for recycling glycerol are needed.

Alternative schemes are proposed to assess the energetic impact of the composition of the feed stream to the dehydration section through process simulation, which saves consuming time, costs and experimentation in the design of bioprocesses.

In the conventional process the feed stream to the dehydration step is a mixture of ethanol-water at the azeotropic point. In the proposed alternative processes, we studied the effect of different ethanol-water mixtures obtained as product in the simple distillation column and its effect on the dehydration step by extractive distillation.