In this analysis, based on the bubble point method, a physical model was established clarifying the interactions (mass and heat) between the species present in the streams in circulation in the column. In order to identify the externally controlled operating parameters, the degree of freedom of the column was determined by using Gibbs phase rule. The mathematical model converted to Fortran code and based on the principles of: 1) Global and local mass conservation balance, 2) Enthalpy balance, and 3) Vapour-liquid equilibrium at each tray, was used to simulate the behavior of the column, concentration distributions, temperature and streams for each phase along the column at high pressure in each tray. The energy consumption at the condenser and the boiler was also evaluated using the Starling equation of state.

To analyze the performance of the separation process, we have introduced thethermodynamic concept of exergy through the exergetic efficiency of the column. Thesimulation results show that the exergetic output is relatively low and that the producedirreversibility fluxes are distributed throughout the whole column in a non-uniform manner.They are particularly significant in the condenser, boiler and tray feed. The influence of thevarious operating parameters (temperature, concentration and irreversibility in both sectionsof the column) is also established. To emphasize the results, the relation in equation 17, ispresented graphically to evaluate the cumulative irreversibilities from the overhead to thebottom. This presentation is equivalent to the Grassmann diagram