Caso de estudio de la destilación etanol-agua en operación continua y discontinua y su simulación con ecuaciones cúbicas de estado y modelos de actividad

Simulating a distillation column represents an interesting problem because of the complex dynamics of the system, the thermodynamic interactions in each tray, and the interaction between internal and external currents. This paper evaluates the operation and simulation of a continuous distillation tower (CDT) and a discontinuous distillation tower (DDT). Such simulation was performed using the McCabe–Thiele and rigorous methods as well as the Forero-Velazquez-Huron-Vidal (FVHV) modified cubic state equation (first proposed by Peng–Robinson) and the No-Random-Two-Liquid (NRTL) activity model. The simulation predicted the composition of the distillate and the bottoms, the number of trays, and the feeding stage. The continuous distillation tower had 9 actual equilibrium trays; but the FVHV equation calculated 8 trays; and the NRTL model, 9. With both models, we found that the optimal number of feeding trays was 7. In the case of the DDT, we carried out two tests (with and without ®™ type packaging). The FVHV equation offers many advantages since all the parameters of pure substances are generalized in terms of thermodynamic properties at the critical point, and it rightly represents polar as well as non-polar substances. Nevertheless, the equation NRTL presented a better fit with the composition of distillate, but, regarding its volume, no model represented the experimental trend. A Microsoft Excel® add-in called ® was used to solve the system of equations, and Euler’s was implemented as an iterative method to solve the equations in the discontinuous distillation tower.