Vapor recompressed batch distillation (VRBD) is an energy-integrated
configuration which works on the principle of a heat pump. Operation of
such a column is challenging due to unsteady, nonlinear dynamics and
strong interplay between separation and energy efficiency. In this
paper, a two-step approach is proposed for optimal operation and control
of such a column. Initially, an openloop optimal operation policy is
generated for maximization of an overall performance index using offline
optimization. To this end, three performance indices are proposed to
capture interplay between separation and energy efficiency.
Subsequently, a model-based output feedback controller is designed to
track this optimal performance trajectory. The effectiveness of the
proposed approach is demonstrated using a benzene-toluene separation
case study wherein it is shown that the proposed approach helps to
achieve optimal operation in the presence of operational disturbances.