Simulation and optimization of extractive distillation sequence with pre-separator for the ethanol dehydration using n-butyl propionate

Extractive distillation is the most promising alternative for the ethanol-water separation than azeotropic and pressure swing distillation using suitable solvent n-Butyl propionate. We have studied, simulated, optimized and economically evaluated the separation of a mixture of 50 mole% ethanol and 50 mole% water to treat the 16 Kmol/hr (512.67 kg/hr) of the original mixture. Rigorous simulation and optimization has been carried out by means of a software CHEMCAD version 6.5 using thermodynamic model UNIQUAC with binary interaction parameters. The simulations allow us to conclude that extractive distillation is more economical and trustworthy than pressure swing distillation due to the relative pressure insensitive nature of the ethanol-water mixture after the azeotropic composition. The separation of 99.7% of ethanol from ethanol water mixture claim by Mulia-Soto, Flores-Tlacuahuac, 2011 is contradictory as the feasibility for the operating pressure of 10 atm with or without heat integration.