Design and control analysis of the side-stream extractive distillation column with low concentration intermediate-boiling entrainer

•Side-stream extractive distillation column is used to separate binary azeotrope.•Low concentration intermediate-boiling entrainer is adopted.•Economics advantages and rationality of low concentration entrainer is studied.•Robust control structures are designed to resist the specified feed disturbances.•Energy consumptions are compared after introducing the specified feed disturbances.