1985 Volume 11 Issue 6 Pages 640-646
A new geometric approach is proposed to evaluate the interaction between two control loops. First, it is shown that manipulated variables of a distillation column can be classified into five groups and that the strength of interaction in various pairs of manipulated variables for dual composition control can be evaluated by using only five transfer vector loci. By applying this method, an effective control scheme is developed. The purity of the distillate is controlled by the ratio of liquid to vapor flow in the enriching section and the purity of the bottom product is controlled by the ratio of liquid to vapor flow in the stripping section. It is confirmed by conducting a simulation of the distillation that this control scheme gives good controlled response to set-point change. In addition, it can also be insensitive to a disturbance in the flow rate and can be realized without complicated calculations
