Dynamic Behavior of Alternative Separation Processes for Ethanol Dehydration by Extractive Distillation

Ethanol is attracting the attention of researchers because of its potential in reducing the dependence on crude oil together with the possible reduction in the pollution associated with the combustion process. The ethanol dehydration process is significant in terms of its production cost. Recently, new distillation sequences have been proposed for the separation of pure ethanol from the fermentation broth. Extending the concept of thermally coupled structures and column sections recombination, already successfully applied to ideal mixtures, it was possible to generate new distillation sequences for azeotropic mixtures. Those configurations are proven to exhibit lower energy consumption together with reduced capital cost compared to the classical sequence proposed in the literature. The aim of this work is the study of the controllability properties under closed-loop operation. Simulation results indicate that the presence of a side stream in extractive distillation sequences does not necessarily provide operational disadvantages; additionally, results also suggest that control properties are ruled by the kind of solvent used.