Optimal Structure of Vapor Recompression Heat Pump Dividing-wall Column for Separating Narrow Boiling Point Mixture

Abstract

Dividing-wall column (DWC) is a special type of thermally coupled distillation. DWC is a common distillation column with a vertical separator, which realizes the function of two columns. This structure enables mass transfer and heat transfer of multiple feed streams in the column at the same time, and realizes the separation task in a column shell which usually needs a conventional distillation sequence. So DWC has unique topology and huge energy saving advantages. However, it is found that a considerable part of the heat provided by the DWC reboiler is removed through the overhead condenser, resulting in a waste of energy. Aiming at three kinds of DWC for separating ternary narrow boiling point mixture, this paper proposes the combination of vapor recompression heat pump (VRHP) and DWC using N-Pentane, Cyclopentane, Isohexane as the input mixture to explore the effectiveness of adding VRHP to DWC to save energy. The optimal steady-state structure of DWC-VRHP is obtained.