Bioethanol recovery and purification using extractive dividing-wall column and pressure swing adsorption: An economic comparison after heat integration and optimization

Extractive dividing-wall column (E-DWC) is a promising alternative to current bioethanol recovery and purification processes, garnering interest from the research community. In this study, E-DWC and pressure swing adsorption (PSA) processes for bioethanol recovery/purification are studied on a consistent basis, and an economic evaluation of both processes is made after heat integration and optimization. For this, realistic feed stream of 10 wt% ethanol, 89.9 wt% water and 0.1 wt% carbon dioxide is considered, and both processes are simulated in Aspen HYSYS v8.2. PSA process involves distillation for removing most of water, before dehydration by PSA. Results indicate that, while E-DWC process has advantages over PSA process in terms of capital cost and thermal energy demand, PSA process still has 33% lower cost of manufacture per unit product than E-DWC process, mostly because of solvent loss. This shows that it is not sufficient to consider only energy requirement in assessing the feasibility of a promising technology; rather, an overall economic evaluation under realistic conditions should be performed. In addition, this work has investigated economies of scale and identified the optimal production capacity of PSA process for bioethanol recovery/purification.