A Note on a Double Temperature-Cascade Control Strategy for Distillation Columns

Abstract

A double temperature-cascade control strategy for controlling distillate composition is proposed. The control structure is based on two secondary loops that are designed for tracking the temperature of one tray in the rectifying and stripping section by manipulation of the reflux rate and reboiler heat input, respectively. Simulation results show that when saturations are imposed on controller outputs (reflux rate and heat input) both cascade controllers can act in a switching-like scheme without interaction problems. It is also shown that an adequate setting of a saturation parameter allows a low energy regulation of distillate composition under disturbances in feed composition.