The aim of this work is the statement of the reasons for different energy effectiveness of extractive distillation systems with the partially coupled heat and material flows (PCEDS) for various mixtures and entrainers. The estimation of the effectiveness was performed for PCEDS application for the separation of seven binary mixtures with different initial compositions and various entrainers. The criterion of the summary power consumption in the reboilers of the columns under the optimal operating parameters was used. It has been concluded on the basis of the obtained results that PCEDS effectiveness depends on the value of the reflux ratio in the entrainer recovery column of the conventional extractive distillation flowsheet. If the reflux ratio in that apparatus has a small value, then the energy consumption decrease due to the use of PCEDS will be insignificant. The criterion for the evaluation of the PCEDS energy efficiency for binary mixtures separation has been formulated as follows: PCEDS is useful if the reflux ratio at the entrainer recovery column has a value equal to or greater than 1. (C) 2015 The Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.