Nonequilibrium Stage Based Modeling of a Falling Film Distillation Unit

A novel nonequilibrium stage based model was developed for a falling film distillation unit. The model combines mass and energy balances in the liquid and vapor phases, without the need of separation efficiency factors. The modeled pilot scale falling film distillation unit is differentiated because the heat supply is carried out axially by means of a thermosyphon. In terms of the algorithm proposed, the central contribution is in reducing the number of variables to be determined by the method, which brings benefits such as reduction of computational time and increase of robustness in the convergence. The results obtained were compared with experimental data from the pilot scale plant, and showed good predictability, with deviations in the top temperature below 2.60%, 6.59% in the distillated ethanol fraction, 12.32% in the resistance power and only one case above 10% for distillate flow rate.