Anhydrous ethanol — extractive distillation past the azeotrope (NRTL)

Producing fuel-grade anhydrous ethanol from a near-azeotropic ethanol/water feed using ethylene glycol as the extractive entrainer. Ordinary distillation is capped at the 89.4 mol% ethanol azeotrope; the high-boiling glycol raises water's relative volatility so ethanol crosses its azeotrope and leaves the extractive column essentially pure, while a vacuum solvent-recovery column strips the water and recycles the glycol. This is modeled with the NRTL activity package on pinned DECHEMA binaries for every pair (ethanol/water, ethanol/glycol, water/glycol) — the non-ideal, azeotrope-crossing VLE a cubic equation of state structurally cannot reproduce (Peng-Robinson stays trapped at the ~89% azeotrope). Honesty note: NRTL binaries come from the bundled DECHEMA VLE Data Collection (via ChemSep/DWSIM), not fitted here; the solvent-recovery column runs under vacuum to keep the glycol below its decomposition temperature.