Model Predictive Control of a High-Purity Internal Thermally Coupled Distillation Column

The energy-saving potential of the internal thermally coupled air separation column (ITCASC) is well-established, but distinct dynamic characteristics and control loop interactions make it inflexible to control. To take care of high-purity ITCASC control complications, a state-space model predictive control (MPC) was formulated. A direct finite-horizon control approach was exploited to align the dynamic states with the model predictions. MPC-I and MPC-II were developed, and further compared to a previous adaptive multivariable generalized prediction control (AM-GPC). The results obtained show that the control performance of the proposed MPC-II is superior to that of MPC-I and AM-GPC.