Limit cycles in homogeneous azeotropic distillation

In spite of significant nonlinearities even in the simplest model, the, dis tillation literature generally takes for granted that distillation columns display relatively simple dynamic behavior. For example, although widely ob served in chemical reactors, any instances of periodic oscillations have no t yet been associated with models of distillation columns. In this paper we study the steady-state and dynamic behavior of the azeotropic distillation of the ternary homogeneous system methanol-methyl butyrate-toluene. Our si mulations reveal nonlinear behavior not reported in earlier studies. Under certain conditions, the open-loop distillation system shows a sustained osc illation (limit cycle). The limit cycles are accompanied by traveling waves inside the column. Significant underdamped oscillations are also observed over a wide range of product rates. To. our knowledge, this is the first si mulation result reporting the presence of Hopf bifurcation points in open-l oop distillation models.