| Summary: | 碩士 === 國立中央大學 === 化學工程研究所 === 81 === Dual composition control of distillation column has been one of
the most pursued research topics in the field of process
control. In addition to the control diffculties caused by loop
interaction, the large numbers of variables, process and
measurement delays, the nonlinear characteristics of many high-
purity distillations has to be considered as well. However,
before nonlinear control algorithms can be readily implemented,
linear control systems will continue to enjoy their popularity
in nonlinear process applications basically because of their
proven reliability and the availability of rigorous stability
and performance evaluation techniques. To overcome the
limitation of control performance of linear feedback
controllers due to nonlinear dynamic behavior of the process,
special strategies baesd on the conventional PI structure such
as nonlinear PI and variable transformation have been proposed.
The primary objective of this study is to compare control
performance of these nonconventional strategies with diagonal
PI and full PI using a low-order nonlinear model derived from a
set of linear transfer function models of a simulated high-
purity distillation column. Test results reveal the fact that a
well designed diagonal PI is compable with nonlinear PI and
variable transformation approach while full PI provides the
best control.
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