Case study of ethanol-water distillation in continuous and discontinuous operation and its simulation with cubic equations of state and activity models

Keywords: Cubic equation of state, Vapour-Liquid Equilibrium, Simulation, Distillation tower, ethanol-water


  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.

Author Biographies

Zulamita Zapata Benabithe *, Universidad Pontificia Bolivariana, Colombia

PhD. en Ingeniería, Grupo de Energía y Termodinámica, Universidad Pontificia Bolivariana, Medellín-Colombia,

Diana Vanegas , Universidad Pontificia Bolivariana, Colombia

PhD. en Ingeniería, Grupo Pulpa y Papel, Universidad Pontificia Bolivariana, Medellín-Colombia,

Juan Camilo Rendón Montoya, Universidad Pontificia Bolivariana, Colombia

Estudiante de Ingeniería Química, Semillero Termo fluidos y Conversión de la Energía, Universidad Pontificia Bolivariana, Medellín-Colombia,

Jorge A. Velásquez , Universidad Pontificia Bolivariana, Colombia

PhD. en Ingeniería Química, Grupo Pulpa y Papel, Universidad Pontificia Bolivariana, Medellín-Colombia,


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How to Cite
Z. Zapata Benabithe, D. Vanegas, J. C. Rendón Montoya, and J. A. Velásquez, “Case study of ethanol-water distillation in continuous and discontinuous operation and its simulation with cubic equations of state and activity models”, TecnoL., vol. 23, no. 49, pp. 223-249, Sep. 2020.


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