Relative Gain Analysis for an Industrial Distillation Column

This paper presents the RGA analysis for a high purity, industrial distillation column. The column was modeled using a commercial computer package for distillation design. The effects of reducing the size of the perturbations on the relative gain array are presented. The results of the RGA analysis indicate degeneracy, suggesting that single composition control is all that should be attempted for this column. Indirect dual composition control for this column is feasible with a strategy consisting of a composition loop for automatic control of one composition combined with a feedforward scheme for control of the other composition. Industrial experience with this strategy supports this conclusion.