Process simulation and optimization of extractive distillation for separating isopropanol-ethanol from IBE fermentation broth as a gasoline additive

Addressing the downstream processing challenges of the bio-butanol fermentation broth (Isopropanol-Butanol-Ethanol-Water), and producing the isopropanol-ethanol mixture with a mass fraction of ≥ 0. 99975 as a high-quality gasoline additive, is crucial for enhancing the overall economy and sustainability of the bio-butanol production process. To obtain the high-purity isopropanol-ethanol mixture, this paper, based on the dehydration-butanol-extractive four column distillation process, proposes a baseline extractive distillation process using a deep eutectic solvent (DES, glycerol: choline chloride = 2: 1) as the extractant, termed the extractive distillation-DES basic process. With heat load as optimization target, the extractive distillation-DES basic process was optimized to determine the optimal operating parameters, termed the extractive distillation-DES sensitivity optimization process. Based on the extractive distillation-DES sensitivity optimization process, the particle swarm optimization algorithm was applied to minimize the total annual cost, resulting in the extractive distillation-DES algorithm optimization process. Compared with the extractive distillation-DES basic process, the total load of the extractive distillation-DES sensitivity optimization process is reduced from 1110. 15 kW to 856. 83 kW (a 22. 82 % reduction) and the total annual cost is reduced from 206, 744. 43 /Y to 157, 726. 17 /Y (a 23. 71 % reduction). The total load of the extractive distillation-DES algorithm optimization process is 874. 18 kW (a 21. 26 % reduction), and the total annual cost is 156, 986. 01 /Y (a 24. 07 % reduction).