Dynamics and Control Simulation of a Debutanizer Column using Aspen HYSYS

In this work, Aspen HYSYS as efficient computer-aided process engineering tools has been applied on a commercial refinery debutanizer column for the separation of an eight-component hydrocarbon mixture. This conventional distillation unit consists of 15 theoretical stages with a total condenser and a rebolier. The representative column is used to recover butane from an unstabilized naphtha feed having components C2 to nC8. The feed is fed at stage 5 (using Aspen HYSYS notation of numbering stages from the reboiler up to the condenser of the column). Both the conventional PID control and the Model Predictive Control (MPC) were applied to the simulation of the Debutanizer column. C4 composition control for distillate product and temperature control for reboiler were applied to control the debutanizer column. The results show that including level into the MPC controller improves composition control for cases in which the manipulated variable for the reflux flow rate has a significant impact on compositions. Simulation results show that MPC controller perform better than the PID control.