Energy-saving heat pump-assisted extractive-azeotropic dividing wall column with heat exchanger network for separating acetonitrile and water: A techno-economic and inherent safety investigation

In the present paper, a new extractive-azeotropic dividing wall column configuration is designed to recover acetonitrile from wastewater instead of the conventional two-column process. Although the performance of energetic and economic savings is enhanced in the dividing wall column, it is still characterised by high energy consumption. To this end, a methodical framework for designing energy-efficient intensified dividing wall columns is developed to gradually reduce the need for utilities. Results indicate that the reboilers of the extractiveazeotropic dividing wall column can be entirely replaced by the applications of vapour recompressed heat pump and heat exchanger network, which comprehensively improves the energy-saving performance. A multi-criteria evaluation of process sustainability, including energy consumption, total cost, environmental performance, energy efficiency, and inherent safety analysis, is performed among the designs. Results show that the heatintegrated extractive-azeotropic dividing wall column process is inherently safer than the conventional twocolumn process and reduces at most 51.95%, 89.96%, and 63.58% in total annual cost, CO2 emissions, and total energy consumption, respectively.