Multiple steady states in distillation: Effect of VL(L)E inaccuracies

Output multiplicities in heterogeneous azeotropic distillation columns were studied. The accuracy of the thermodynamic description is a key factor tha t determines if multiplicities can be observed in numerical simulations. Th e descriptions used in the multiplicity-related literature are analyzed. Th e infinity/infinity analysis of Bekiaris et al. (1996) was used to check im plications of inaccuracies in the reported thermodynamics on the existence of multiplicities in azeotropic distillation. On this basis, guidelines are derived concerning what features of thermodynamic descriptions need specia l attention for use in multiplicity prediction and simulation. Secondly, nu merical studies on output multiplicities in heterogeneous azeotropic distil lation in the literature were compared to the infinity/infinity predictions wherever possible. The infinity/infinity analysis was used to derive the r elations between the reported multiplicities and to identify the physical p henomena causing them.