Improved design of heat-pump extractive distillation based on the process optimization and multi-criteria sustainability analysis

In order to achieve the sustainable separation design of azeotropic mixtures, this study proposed a systematic framework for distillation process optimization and intensification based on a composite sustainability index. Binary minimum azeotropic mixture ethanol-ethyl propionate was studied as an illustrative example. Specifically, three extractive distillation configurations were firstly applied on the separation and the sustainability of distillation processes were evaluated comprehensively. The composite sustainability index was constructed with the indicators of the economic, environmental, technical and social dimensions, and fuzzy weighting method was used to determine the weight of each indicator. Then, the process can be optimized with the objective of the composite sustainability index by the mesh adaptive direct search algorithm. After that, the heat-pump is further implemented to make full use of the latent heat of vapor stream in the distillation system. The T-H diagram of two upgraded processes clearly demonstrates the heat recovery while considering the specified minimum heat-transfer temperature difference.