Intrinsic characteristics of distillation such as dead time and high nonlinearities do not allow the complete elimination of transient times when any external disturbance or set‐point change occurs. Thus, aiming at the use of easy‐tuning systems, a distributed‐action control in trays of a diabatic distillation unit with Smith's predictor was implemented in the Simulink environment to further reduce transient times and out‐of‐specification product. The distributed‐action strategy with Smith's predictor led to a reduction of 33.3 min (33 %) in the transient time of the top temperature control loop and 66 % in out‐of‐specification product, when compared with the conventional strategy, and thus is shown to be an efficient approach to increasing the productivity of distillation plants.

A control strategy with distributed corrective action for distillation has been proposed and consists of a conventional dual temperature control combined with an additional column tray. In this work, we evaluated the influence of the location of this internal loop as part of the new proposal, compared to a conventional system. Tests were carried out in a 13-column tray distillation equipment and feed temperature was disturbed. Two different column trays from the stripping section were used (11 and 12) for internal decentralized temperature control, each one separately, plus the dual control of top and bottom temperatures. The results demonstrated that this proposed control approach with distributed corrective action is faster than the conventional one, regardless of the column tray in use. It was also determined that the internal loop close to the feed (disturbance) is more interesting as a way to minimize transients.