Inverted decoupling: a neglected technique

In a conventional decoupling control scheme, process inputs (signals to valves or set points to lower level flow controllers) are produced as a time-weighted combination of process controller outputs. A lesser known technique, here called ''inverted decoupling'', produces the process input signals by combining one controller output with the other process input signals. Where this technique is applicable, it has several advantages over conventional decoupling. These advantages as well as potential problems are addressed in this paper. Simulation results, related to distillation column applications, are also presented. (C) 1997 ISA. Published by Elsevier Science Ltd.