1. ITK-234 Termodinamika Teknik Kimia II
VLE Calculations for Nonideal Mixtures
Dicky Dermawan

2. Modified Raoult’s Law K-value Method VLE using Equation of States
Dicky Dermawan

3. Modified Raoult’s Law:
Incorporation of fugacity and activity coefficient to vle criteria results:
where
However, at low pressure (up to at least 1 bar):
The Poynting Factor 1
Modified Raoult’s Law:

4. Modified Raoult’s Law: Wilson Equation for calculating 
Prepare a P-x-y diagram at 80oC
Prepare a t-x-y diagram at 101,33 kPa

5. Modified Raoult’s Law: Wilson Equation for calculating  (Cont’)
Use your diagram to answer there questions:
Given P = 70 kPa, T = 80oC & overall composition, z1=30%
Find the fraction of system which is liquid (L) & vapor (V) and their respective compositions xi & yi

6. Modified Raoult’s Law: Wilson Equation for calculating 
Prepare a P-x-y diagram at 80oC
Prepare a t-x-y diagram at 101,33 kPa

7. Modified Raoult’s Law: Wilson Equation for calculating  (Cont’)
Use your diagram to answer there questions:

8. Modified Raoult’s Law: Wilson Equation for calculating 

9. Modified Raoult’s Law: Wilson Equation for calculating 

10. Modified Raoult’s Law: Wilson Equation for calculating 

11. Modified Raoult’s Law: Wilson Equation for calculating 

12. Modified Raoult’s Law: Wilson Equation for calculating 

13. Modified Raoult’s Law: Wilson Equation for calculating 

14. Modified Raoult’s Law: Wilson Equation for calculating 

15. Modified Raoult’s Law: Wilson Equation for calculating 

16. Modified Raoult’s Law: NRTL Equation for calculating 
Prepare a P-x-y diagram at 80oC
Prepare a t-x-y diagram at 101,33 kPa

17. Modified Raoult’s Law: NRTL Equation for calculating 

18. VLE Calculation Using No Diagram
Answer the questions (a) through (e) from 12.6 to but don’t use the phase diagram to obtain the answers

19. Estimating Azeotrophic Condition, Use No Diagram

20. K-Value Method: Using De Priester Charts for light hidrocarbons
The nomographs K = f(T,P) prepared by De Priester provide easy application of this approach to practical problem

21. K-Value Method: Using De Priester Charts for light hidrocarbons
High
Temperature
Range

22. K-Value Method: Using De Priester Charts for light hidrocarbons
Low
Temperature
Range

23. Type of Phase Equilibria Calculations
BUBL P calculation:
Given T & liquid composition xi,
Find the bubble point Pb & vapor composition
DEW P calculation:
Given T & vapor composition yi,
Assume P, find Ki satisfying:
Assume P, find Ki satisfying:

24. Type of Phase Equilibria Calculations
BUBL t calculation:
Given P & liquid composition xi,
Find the bubble point Pb & vapor composition
DEW t calculation:
Given P & vapor composition yi,
Assume t, find Ki satisfying:
Assume t, find Ki satisfying:

25. K-Value Method: Using De Priester Charts for light hidrocarbons

26. K-Value Method: Using De Priester Charts for light hidrocarbons

27. Type of Phase Equilibria Calculations
FLASH calculation:
Given P, T & overall composition,
Find the fraction of system which is liquid (L) & vapor (V) and their respective compositions xi & yi
Make sure P located between Pb dan Pd, i.e.
Perform BUBL P for zi =xi and
Perform DEW P for zi = yi
Find Ki ; assume V satisfying:
or:
or: The General Solution Procedure

28. K-Value Method: Using De Priester Charts for light hidrocarbons

29. K-Value Method: Using De Priester Charts for light hidrocarbons

30. K-Value Method: Using De Priester Charts for light hidrocarbons