Unit Operations Lecture 20 03 Nov 2010 1 McCabe-Thiele – AZ diagrams Ethanol – Water Binary (1.013 bar): 2 Overview •Review Review rigorous methods / RADFRAC • Multicomponent systems: o Residue curves o DSTWU / RADFRAC o Rules of thumb • Complex (Enhanced) distillation • Column internals • Batch distillation 3 Azeotropic Distillation Perry’s 8th ed. 4 Heterogeneous Azeotropic Distillation VLLE (NRTL) ( ) 5 Heterogeneous Azeotropic Distillation Perry’s 8th ed. 6 Residue Curve Maps 7 Complex Multicomponent Systems 8 Pressure Swing Distillation 9 Pressure Swing Distillation 10 Complex or Enhanced Distillation • Extractive Distillation o Higher boiling solvent o Enters near top of column o Interacts with other components to affect volatility or activity coefficients • Homogeneous Azeotropic Distillation o Add entrainer that forms min/max boiling point AZ w/ 1 or more of feed compds o Added near top or bottom, depending upon if AZ is min or max BP • Heterogeneous Azeotropic Distillation o Add entrainer to form min BP heterogeneous azeotrope (EtOH-H2O + benzene) • Pressure – Swing Distillation o For pressure sensitive azeotropes and distillation boundaries • Salt Distillation o Alter relative volatilities of feed compds by dissolving a soluble ionic salt into the reflux • Steam Distillation o Steam is added to reduce temperature of distilling organic mixture • Reactive Distillation o add reactant &/or catalyst to cause a reversible/selective reaction with one of the feed components o Reaction and distillation occur in same vessel 11 Reactive Distillation • Esterification of acetic acid with ethanol to ethyl y acetate and water EtOH AA EA H 2O 12 Column Internals 13 Column Internals 14