Abstract
The biobutanol stream obtained after the fermentation step in the acetone–butanol–ethanol process has a low concentration (less than 3 wt % butanol) that leads to high energy usage for conventional downstream separation. To overcome the high downstream processing costs, this study proposes a novel intensified separation process based on a heat pump (vapor recompression)-assisted azeotropic dividing-wall column (A-DWC). Pinch analysis and rigorous process simulations have been used for the process synthesis, design, and optimization of this novel sustainable process. Remarkably, the energy requirement for butanol separation using heat integration and vapor recompression assisted A-DWC is reduced by 58% from 6.3 to 2.7 MJ/kg butanol.
Highlights
Biomass is a natural way of storing solar energy which can be converted afterward into biofuels
To overcome the high downstream processing costs, this study proposes a novel intensified separation process based on a heat pump-assisted azeotropic dividing-wall column (A-dividing wall column (DWC))
The organic phase is recycled on the second stage of the right stripping section (15th stage of A-DWC), from which butanol is obtained as a bottom product
Summary
Biomass is a natural way of storing solar energy which can be converted afterward into biofuels. The proposed heat integration for the new process design preheats the column-inlet streams to 97 °C For this reason, every stream crosses a heat exchanger, being heated as follows: the initial feed stream is heated with the compressed vapors, while the aqueous and organic phase streams are heated by the hot water product stream. This figure could be further reduced (by 25%) if the electricity used by the compressor of the heat pump comes from renewable sources (e.g., wind, solar, geothermal)
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