Conventional Proportional-Integral Control of a Dividing-Wall Distillation Column with Discrete Measurements

The problem of controlling an energy-efficient dividing-wall distillation column (DWDC) with a discrete key variable measurement is addressed. Usually, controllers are tuned in a systematic and simultaneous way, based on a certain control system configuration and conventional discrete proportional-integral controllers. The same stable pole-assignment approach to linear dynamics is followed here that approximately describes the convergence of each control loop. Tuning relationships in terms of sampling time and predecessor parameters of physical insight are obtained. The control system performance is simulated for disturbance rejection in an energy-efficient DWDC for separating a ternary mixture of benzene, toluene, and xylene. This tuning technique can be effective with a sampling time as long as that corresponding to current measurement instruments.