Energy efficient design of bio-butanol purification process from acetone butanol ethanol fermentation

Abstract

Butanol has the potential as a transportation fuel since its energy density is similar to gasoline and higher than ethanol. The Acetone-Butanol-Ethanol (ABE) fermentation is the current main method to produce bio-butanol where the fermentation should be operated in diluted surroundings to avoid toxicity to microorganisms. This article aims to develop efficient separation sequences to purify individual components from the ABE fermentation. The base design comes from the reference proposed by Patraşcu et al. [3]. With an updated thermodynamic model, several novel design alternatives are proposed and investigated to reduce energy consumption in the separation sequences. Therein, the proposal of removing acetone at first, and purifying ethanol via integration of distillation and membrace not only reduces total energy consumption and total annual cost by 57% and 52%, but also reaches targeting purity of 99.5% for butanol, acetone and ethanol. Heat integration and column stacking can reduce the overall energy consumption furthermore. This study also carries on plantwide control for the processes with heat integration and column stacking. The superior control performance with ±10% changes in throughput and feed compositions is validated for the proposed plantwide process control scheme.