Comparison of stabilizing control structures for dividing wall columns

The focus of this paper is to investigate stabilizing control (single-loop PID control) of a dividing wall column (DWC) for separating ethanol, n-propanol and n-butanol at atmospheric pressure. Three control structures are studied: control structure with fixed split ratios (CS1), control structure with an active liquid split (CS2) and control structure with an active vapor split ratio (CS3). The dynamic performances of the three proposed control structures prove that the three control structures are able to handle feed disturbances inserted into DWC. The simple control structure with fixed split ratios (CS1) is more applicable in industry. Considering the vapor split ratio disturbance, CS2 and CS3 are better than CS1. If the feed composition of A rarely changes, CS3 is able to handle the other feed disturbances. This paper proves that the three-product DWC can be controlled with only three temperature controllers.