Investigation of an energy-saving double-thermally coupled extractive distillation for separating ternary system benzene/toluene/cyclohexane

An intensified scheme for the separation of ternary azeotropic system is explored to reduce the energy consumption and recycle important organic solvents. Herein, a novel double-thermally coupled ternary extractive distillation (DTCTED) for separating azeotropic system benzene/toluene/cyclohexane (denoted as B/T/CH) is proposed to achieve energy-saving and emissions reduction. Thermodynamic feasible insights of the B/T/CH using dimethyl formamide as entrainer are firstly analyzed via residue curve maps to find separation constraints. Following that, the proposed intensified scheme is optimized via the in-house multi-objective genetic algorithm software while using total annual cost and CO2 emissions as objective functions. The results show that the total annual cost and CO2 emissions of the proposed intensified DTCTED scheme are significantly reduced by 18.60% and 20.22% compared with the existing single-thermally coupled ternary extractive distillation process. Furthermore, exergy loss and relative volatility are introduced to explore the essence of energy-saving in the proposed DTCTED scheme. •An intensified double-thermally coupled ternary extractive distillation is proposed.•The proposed scheme is optimized based on the multi-objective genetic algorithm.•Proposed scheme can save 18.60% and 20.22% of total annual cost and CO2 emissions.•Essence of the energy-saving is explored by exergy loss and relative volatility.