Control of distillation columns with non-monotonic temperature behavior

In this paper, we describe an unusual behavior which has been observed in the simulation of a practical extractive distillation column (tray) involving three components. Although the column temperature profile does not exhibit any temperature inversion, some tray temperatures, including the one used for control, are nonmonotonic with respect to input variables such as reboiler duty and entrainer flow. Its practical implication on temperature control is discussed.