1. CBE 417 “Unit Operations” 1 Lecture: 3 7 Sep 2012

2. Overview 2 Introduction UO course overview Equilibrium Stage separations What are “Unit Operations” Brief thermodynamics review Binary flash with energy balance Multicomponent flash

3. Vapor Liquid Equilibrium (VLE) 3 Typical simplifications: Ideal vapor phase Ideal liquid phase

4. Phase Equilibrium (Alternate Form VLE) 4 Historically, when estimates were done by hand: Seader & Henley (2006)

5. Phase Equilibrium (Recommendations) 5

6. Phase Equilibrium (Alternate Form VLE) 6 Historically, when estimates were done by hand: Sometimes the K values are nearly composition independent “hand” techniques of design/solution have used DePriester Charts (hydrocarbons):

7. DePriester Chart 7 P = 2 bar T = 100 o C Isobutane others….

8. DePriester (equation fit) 8

9. Other Equilibrium Diagrams: 9 P = 1.013 bar T = various o C Benzene - Toluene

10. Other Equilibrium Diagrams: 10

11. Effect of Pressure: 11

12. Effect of Pressure: 12 Seader & Henley (2006)

13. Other Equilibrium Diagrams: 13

14. Overview 14 Brief thermodynamics review Binary Flash with energy balance Sequential solution Simultaneous solution Multicomponent Flash

15. Binary Flash 15 Overall mole balance mole balance on a mole balance on b equilibrium eqn for a mole balance on a

16. Binary Flash 16 Flash separation: Specify: Find: a = n-pentane b = n-hexane Vfrac0.471 V/F P3.000bar functi on - 1.89E- 08 Xa0.394 Xb0.606 Ya0.619 Yb0.381

17. Binary Flash 17 Overall mole balance mole balance on a mole balance on b equilibrium eqn for a mole balance on a

18. Binary Flash 18 Flash separation: Specify: Find: a = n-pentane b = n-hexane

19. Binary Flash 19 Graphical Solution: mole balance on a solve for y a “Operating Line”

20. Binary Flash 20 Graphical: y = x Equilibrium curve Za Solution! What if f is unknown, but T is known? Limits: f = 0 f = 1

21. Binary Flash Energy Balance 21 EB on CV:

22. Other Equilibrium Diagrams: 22

23. Alternative Thermodynamics 23 Older (hand methods): Relative Volatility (VLE): Raoult’s law Aside (couple with MB)

24. Separation Factor or Relative Volatility 24

25. Effect of Pressure: 25 Seader & Henley (2006)

26. Constant Relative Volatility? 26

27. Alternative Thermodynamics 27 K i with multicomponent flash: Sequential solution: suggestions p 35-37 (Rachford-Rice Eqn) Simultaneous solution technique: suggestions p 40-43 Into MB:

28. Sizing Flash Drums 28

29. Simulators 29 Flash input: Sensitivity Analysis: Design Spec:

30. Questions? 30