Prog.,85, April 1978 copyright 1978, AIChE reproduced by permission of the American Institute ofChemical Engineers) From Separation Process Engineering, Third Edition by Phillip C. At 2000 kPa, what is the boiling point of ethane? volatility At 15 C, what is the saturated vapor pressure of isobutane?At 0 C and500 kPa, what is the volatility of n-hexane?Using data from vapor pressure tables Raoults Lawideal liquid: non-ideal liquid: Daltons Lawideal gas: non-ideal gas: PA xAPA0(T)PA AxAPA0(T)yA PAPTOTALyA PA Wankat(ISBN: 0131382276) Copyright 2012 Pearson Education, Inc. PA0(T)PTOTALactivity coefficient fugacity coefficient vapor pressure Bubble point calculation for multi-component mixtures Trial-and-error method Given the composition of a subcooled liquid and PTOTAL,find Tbp and (yi)bp VLE: mole balance: yi Kixiyii1.0Algorithm: 1. Pick a temperature T and find the corresponding Ki(T) values for each component 2. If not, pick a new temperature, repeat How to pick a temperature? How to pick the next temperature? To achieve rapid convergence: Initial guess:(weighted average of boiling points of pure components) T ziTii(Ki 1)KA(Tnext) KA(Tprev)(yi)previNext guess: pick a reference component (A) find Tnext using DePriester Chart Dew point calculation for multi-component mixtures Trial-and-error method Given the composition of a superheated vapor and PTOTAL,find Tdp and (xi)dp VLE: mole balance: xi yiKixii1.0Algorithm: 1.

Depriester chart for ethanol