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Stabilization of an unstable distillation column


C. Dorn, T.E. GŁttinger, G.J. Wells, M. Morari, A. Kienle, E. Klein, E.D. Gilles

Industrial & Engineering Chemistry Research, vol. 37, no. 2, pp. 506-515

Bekiaris et al. (1993) explained the existence of multiple steady states in homogeneous azeotropic distillation on the basis of the analysis of columns with infinite reflux and infinite length (infinite number of trays). They showed that the predictions of multiple steady states for such infinite columns have relevant implications for columns of finite length operated at finite reflux. The first experimental verification of the existence of such multiple steady states was published by GŁttinger et al. (1997) Using an industrial pilot column without automatic control system, they confirmed the existence of two stable steady states for the ternary homogeneous system methanol-methyl butyrate-toluene. That is, two different column profiles occurred for the same operating parameters, feed flow rate, and feed composition. In this article, experiments for the same ternary system are described which show the existence of a third unstable steady state. The unstable steady state is stabilized with PI-control. Furthermore, the transition from an unstable to a stable operating point is demonstrated when the control action is removed.

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% Autogenerated BibTeX entry
@Article { DorEtal:1998:IFA_329,
    author={C. Dorn and T.E. G{\"u}ttinger and G.J. Wells and M. Morari and A.
	  Kienle and E. Klein and E.D. Gilles},
    title={{Stabilization of an unstable distillation column}},
    journal={Industrial \& Engineering Chemistry Research},
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