Process intensification and dynamic control of a vapor-recompression-assisted heterogeneous azeotropic distillation for separating N-butanol/water

Abstract

An ecologically beneficial process of vapor-recompression-assisted distillation was proposed, based on the conventional heterogeneous azeotropic distillation, for separating n-butanol and water. The heat integration was also adopted to improve the energy utilization rate of the process. The sequential iterative approach optimized the parameters relating to all those processes. The heat-integrated vapor-recompression-assisted heterogeneous azeotropic distillation arrangement reflects its economic superiority, for reducing total annual cost by 15.121 % and CO₂ emissions by 78.860 % and enhancing second-law efficiency by 102.156 %. An exergy analysis was performed on the intensified processes, which showed that the exergy increases in the configuration coupled with vapor recompression and heat integration were higher than those with only vapor recompression. Dynamic control characteristics were investigated for these three intensified configurations, and both product compositions were well controlled when confronting 20% production rate and feed composition disturbances, and no composition measurement loops were noted in the proposed control schemes.