Improving the economic saving, environmental sustainability, and energy efficiency of separating acetone/n-heptane mixture via heat pump-assisted extractive dividing wall column with heat exchanger network

The separation of the acetone/n-heptane mixture is challenging in the industry due to the presence of a minimum-boiling azeotrope which attracts considerable interest in recent years. However, few studies concern with the energy-efficient design for this separation toward sustainable development. The present work explored the possibility of using an extractive dividing wall column with heat pump and heat exchanger network to improve the sustainability of the separation process for the acetone/n-heptane mixture. Four energy-efficient extractive dividing wall column designs are proposed following a systematic approach by gradually decreasing the energy consumption to facilitate the separation, based on the process intensification methods, including feed preheating, heat pump, and heat exchanger network. A multi-criterion performance evaluation, including energy consumption, economic cost, CO2 emissions, and thermodynamic efficiency, is carried out amongst all proposed designs and compared with the two-column conventional extractive distillation and side -stream extractive distillation processes. Results show that the finalised heat pump-assisted extractive dividing wall configuration with feed preheating and heat exchanger network achieves the best performance with re-ductions in total energy consumption, total annual cost, and CO2 emissions of 38%, 20%, and 41%, respectively. Special attention is paid to checking the compression process in heat pump design for safety concerns through the temperature-entropy diagram. The proposed strategy in the present work can reference designing energy -efficient extractive distillation configurations for other azeotropes separations toward sustainable development.