Inferential Temperature Control Structures for Different Types of Two-Reactant Reactive Distillation Systems

The control performance of three types of two-temperature inferential control structures for the economic optimum designs of two-reactant ideal reactive distillation systems is evaluated. Three commonly encountered reaction chemistries are studied, namely, a single-product ternary system without inert, a single-product ternary system with inert, and a two-product quaternary system. Closed loop results for the different reactive distillation systems demonstrate significant differences in terms of workable control structures and appropriate temperature control tray locations. A suitable two-temperature inferential control structure for the optimum designs of all the systems is found. The result for the ternary system with inert is in contrast to recent reports claiming the need for column internal composition control. The results also suggest that, with a properly designed two-temperature inferential control system, column overdesign for good controllability is not needed.