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CBE 417 “Unit Operations”

CBE 417 “Unit Operations”. Lecture: 2. 31 Aug 2012. Technological Maturity. Seader & Henley (2006). Separations as Unit Operations. Ease of Scale-up. Seader & Henley (2006). Unit Operation. What is a “Unit Operation”?. Choosing a Unit Operation.

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CBE 417 “Unit Operations”

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  1. CBE 417 “Unit Operations” Lecture: 2 31 Aug 2012

  2. Technological Maturity • Seader & Henley (2006)

  3. Separations as Unit Operations Ease of Scale-up • Seader & Henley (2006)

  4. Unit Operation What is a “Unit Operation”?

  5. Choosing a Unit Operation How does one choose a UO? i.e. ethanol from water separation • Seader & Henley (2006)

  6. Separations as Unit Operations • Seader & Henley (2006)

  7. Seader & Henley (2006)

  8. Seader & Henley (2006)

  9. Seader & Henley (2006)

  10. Seader & Henley (2006)

  11. Seader & Henley (2006)

  12. Seader & Henley (2006)

  13. Today’s Process Engineering • Today, most of major unit operations are built into a process simulator and used extensively within the industry. For example: • Simulators: AspenPlus, Fluent, Comsol, ChemSep, others.

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

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

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

  17. Phase Equilibrium (Recommendations)

  18. Phase Equilibrium (Alternate Form VLE) 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):

  19. DePriester Chart P = 2 bar T = 100 oC Isobutane others….

  20. DePriester(equation fit)

  21. Other Equilibrium Diagrams: P = 1.013 bar T = various oC Benzene - Toluene

  22. Other Equilibrium Diagrams:

  23. Effect of Pressure:

  24. Effect of Pressure: • Seader & Henley (2006)

  25. Other Equilibrium Diagrams:

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

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

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

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

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

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

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

  33. Binary Flash Energy Balance EB on CV:

  34. Other Equilibrium Diagrams:

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

  36. Separation Factor or Relative Volatility

  37. Effect of Pressure: • Seader & Henley (2006)

  38. Constant Relative Volatility?

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

  40. Sizing Flash Drums

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

  42. Questions?

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