MULTIPLICITY OF STEADY STATES IN A NON-EQUILIBRIUM SIMPLE BATCH DISTILLATION PROCESS

RESUMO – In this work, an analysis was made of the changes in compositional trajectories for the mixture of methanol/isopropanol/water close to distillation boundaries, when the non-equilibrium approach was applied to a simple batch distillation process. Numerically different values of binary azeotropes were observed for different values of the interfacial area in the process of mass transfer between the liquid phase and the vapor phase, and for the different molar flow rates in distillation. It was also observed that when a distiller has a large interfacial area or a small molar flow value for vapor removal, the residue curves and the distillation boundaries (separatrices) of the irreversible model resemble the curves simulated by the model of equilibrium. In the construction of residue curves near the separatrices, a change in stability was observed, which, depending on the design of the equipment (interfacial area) or the operational condition (molar flow of vapor), could result in a steady state with the heavy component or an intermediate component as the bottom product. A bifurcation analysis was carried out, using MATCONT software, to map the steady states of the process, through the construction of bifurcation diagrams (in co-dimension 1) using the interfacial area and the molar flow rate as the parameters of continuation. With this, it was possible to determine the critical value of the parameters of continuation where a change in stability could be observed.