The Equivalence of Non-Interacting Control System Design Methods in Distillation

Singular Value Analysis has been used to design structural compensators for the material balance control scheme in distillation. The control system obtained is similar to (1) column profile control, (2) implicit decoupling, (3) modal control, (4) output decoupling and, under some conditions, (5) extensive variable control. The material balance control scheme does not require an input compensator because the right singular vectors (input rotation matrix) are naturally aligned with the standard basis vectors. The output compensator (measurement matrix) is designed to create a non-interacting output frame. The resulting control scheme pairs distillate flowrate with the sum of two tray temperatures, and reboiler heat duty with the difference between the tray temperatures.