Energy efficiency of acetone, butanol, and ethanol (ABE) recovery by heat-integrated distillation.

Abstract

Acetone, butanol, and ethanol (ABE) is an alternative biofuel. However, the energy requirement of ABE recovery by distillation is considered elevated (> 15.2MJ fuel/Kg-ABE), due to the low concentration of ABE from fermentation broths (between 15 and 30g/l). In this work, to reduce the energy requirements of ABE recovery, four processes of heat-integrated distillation were proposed. The energy requirements and economic evaluations were performed using the fermentation broths of several biocatalysts. Energy requirements of the processes with four distillation columns and three distillation columns were similar (between 7.7 and 11.7MJ fuel/kg-ABE). Double-effect system (DED) with four columns was the most economical process (0.12-0.16 $/kg-ABE). ABE recovery from dilute solutions by DED achieved energy requirements between 6.1 and 8.7MJ fuel/kg-ABE. Vapor compression distillation (VCD) reached the lowest energy consumptions (between 4.7 and 7.3MJ fuel/kg-ABE). Energy requirements for ABE recovery DED and VCD were lower than that for integrated reactors. The energy requirements of ABE production were between 1.3- and 2.0-fold higher than that for alternative biofuels (ethanol or isobutanol). However, the energy efficiency of ABE production was equivalent than that for ethanol and isobutanol (between 0.71 and 0.76) because of hydrogen production in ABE fermentation.