Comparative Analysis of Extractive Distillation Systems with Different Phase States of Side Withdrawal from an Extractive Distillation Column

The effect of the aggregate state of side withdrawal on the energy consumption of extractive distillation (ED) systems including a side-stream ED column has been studied by the examples of separation of three binary mixtures: acetone–chloroform, acetone–methanol, and benzene–cyclohexane. For each mixture, the optimal parameters in terms of the total energy consumption in column reboilers have been determined for four systems: a conventional double-column system, a system with partially coupled heat and material flows, a system including a side-stream ED column with side withdrawal in the vapor phase, and a system including a side-stream ED column with side withdrawal in the liquid phase. It has been found that the energy consumption in column reboilers of the system with partially coupled heat and material flows and the system including a side-stream ED column is almost the same and lower than in column reboilers of the conventional double-column system. However, the number of theoretical trays (TTs) in the systems with a side-stream ED column is greater than in the systems with partially coupled heat and material flows. It has been found that the aggregate state of side withdrawal barely affects the total energy consumption in column boilers of the systems with a side-stream ED column.