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Nonlinear Dynamics in Homogeneous Azeotropic Distillation


C. Dorn

vol. Diss. ETH Nr. 13947

The main focus of this work is on the dynamic behavior of homogeneous azeotropic distillation columns. So far, instability of steady states in distillation has been studied mostly in connection with multiplicities. The main contribution is the Qualitative Dynamic Analysis, a graphical framework that allows a qualitative analysis of the local stability of column profiles for columns of finite length operated at infinite internal flows. The information gained from this qualitative stability analysis can be merged with the results of an $infty / infty$ analysis in order to construct complete bifurcation diagrams that include bifurcation points of codimension one such as the fold, Hopf, or homoclinic bifurcation. The qualitative bifurcation analysis allows to predict and locate limit cycles and to explain the occurrence of homoclinic bifurcations. Studying the influence of the feed composition, bifurcations of higher codimension can be predicted. It is discussed how the method carries over to the case of finite reflux. The method is generalized and extended to cases of mixtures whose residue curve maps have complex topologies. All theoretical predictions are verified in numerical simulations using different mixtures and different models for the column and the vapor-liquid equilibrium. The insight is gained on physical grounds {without} numerical simulations of the distillation column but by interpretation of the residue curve map of the corresponding mixture. The residue curve map illustrates some {physical properties} of a mixture, and therefore does not depend on the thermodynamical model used as it basically could also be measured. Therefore, most of the theoretical results depend only quantitatively on the thermodynamical model used, but not qualitatively.

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Type of Publication:

(03)Ph.D. Thesis

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% Autogenerated BibTeX entry
@PhDThesis { Xxx:2000:IFA_322,
    author={C. Dorn},
    title={{Nonlinear Dynamics in Homogeneous Azeotropic Distillation}},
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