Plant-wide economic comparison of lactic acid recovery processes by reactive distillation with different alcohols

Process designs for the continuous recovery of lactic acid from fermentation broth by reactive distillation (esterification and hydrolysis with C1 to C4 alcohols) are developed and optimized to minimize cost. The best designs are qualitatively different for different alcohols because of the differing volatility ranking of reactants and products and the formation of a two-liquid phase zone in some cases. The results suggest that the methanol and butanol processes are the most attractive. The costs of these two processes are similar, and the ranking depends on the payback period. The ethanol and isopropyl alcohol processes are more expensive because an entrainer is required to break the alcohol/water azeotrope.