“Dynamics and control of unstable distillation columns”

Authors: Elling W. Jacobsen and Sigurd Skogestad,
Affiliation: NTNU, Department of Chemical Engineering
Reference: 1993, Vol 14, No 2, pp. 59-72.

Keywords: Distillation, multiple steady states, instability, limit cycles

Abstract: The fact that ideal two-product distillation columns may have multiple steady states and unstable operating points has only recently been recognized. This paper discusses the dynamics and control implications. It is shown that columns operating with reflux and boilup as independent variables become unstable if the internal flows are sufficiently large. An open-loop unstable operating point may be stabilized by use of one-point control, i.e., feedback control of a column composition or temperature. If the control is not sufficiently tight, the column may go into a stable limit cycle. Finally, it is shown that with distillate flow and boilup as independent variables the operating points may become unstable if the level control is not sufficiently tight. The column may also in this case go into a stable limit cycle.

PDF PDF (1522 Kb)        DOI: 10.4173/mic.1993.2.1

DOI forward links to this article:
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  title={{Dynamics and control of unstable distillation columns}},
  author={Jacobsen, Elling W. and Skogestad, Sigurd},
  journal={Modeling, Identification and Control},
  publisher={Norwegian Society of Automatic Control}