Long-Range Predictive Control with Pole Placement and Double Serie-Parallel Reference Model of a Kuhni Column

Abstract

This paper describes the application of the long-range predictive control with pole placement and double serie-parallel reference model to mecanically agitated Kühni columns. In previous works (Carrier, 1981) it has been stated that the flooding conditions of a pulsed column for liquid-liquid extraction might be controlled by measuring the conductivity of the liquid medium at a place located between the dispersed phase inlet and the continuous phase outlet. The pulsing intensity was the command variable. In this paper, it is demonstrated that the same control strategy may be similarly applied to a very different type of agitated column, the Kühni contactor which is a major representative of the rotary mixed columns. The controlled variable remains the conductivity measured at a similar location in the column, whereas the pulsing frequency has been replaced by the rotation speed of the central shaft which wears the mixing turbines. The same single input-output linear discrete model with time varying parameters has been adopted in order to model the even more complicated dynamic behaviour of the column. Good results have been obtained, allowing to conclude that the proposed strategy might be of valuable interest whatever the kind of mechanically agitated contactor involved.