Tuning of dual-composition distillation column control

✍ Scribed by H.W. Andersen; M. Kümmel; A. Nørgaard Hansen; K. Nielsen

• Publisher: Elsevier Science
• Year: 1989
• Tongue: English
• Weight: 978 KB
• Volume: 44
• Category: Article
• ISSN: 0009-2509
• DOI: 10.1016/0009-2509(89)85038-9

✦ Synopsis

A frequency domain approach is used to compare the nominal performance and robustness of dual-composition distillation column control tuned according to Ziegler-Nichols (ZN) and Biggest Log Modulus Tuning (BLT) for three binary distillation columns. The scope of this paper is to examine whether ZN and BLT design yield satisfactory control of distillation columns. Further, PI controllers are tuned according to a proposed multivariable frequency domain method. A result is that the ZN-tuned controllers yield an undesired overshoot and oscillation and poor stability robustness properties, whereas BLT tuning removes the overshoot and oscillation, but at the expense of a more sluggish response. It is concluded that, if a simple control design is to be used, the BLT method should be preferred compared to the ZN method. The frequency domain design approach presented yields a more proper trade off between oscillation, response time and stability robustness. However, this method is more complicated to use than the ZN and BLT methods. Moreover, it is shown that properly tuned diagonal PI controllers can provide performance and robustness properties which equal well-tuned PI controllers extended with decoupling. It is also illustrated how servo filtering can be used to yield a proper trade off between performance and high-frequency control effort. The properties of the different controllers are illustrated by transient simulations.