1. Chemical Reaction Engineering (CRE) is the field that studies the rates and mechanisms of chemical reactions and the design of the reactors in which they take place. Lecture 2 1

2. Lecture 2 – Tuesday 1/10/2011 Review of Lecture 1 Definition of Conversion, X Develop the Design Equations in Terms of X Size CSTRs and PFRs given –r A = f(X) Conversion for Reactors in Series Review the Fall of the Tower of CRE 2

3. ReactorDifferentialAlgebraicIntegral CSTR Batch NANA t PFR FAFA V 3

4. 4 Liquid phase Given the following information, Find V

5. (1) Mole Balance: (2) Rate Law: (3) Stoichiometry: 5

6. (4) Combine: (5) Evaluate: 6

7. Consider the generic reaction 7

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9. Integrating The necessary t to achieve conversion X. 9

10. Steady State 10 Well Mixed

11. CSTR volume necessary to achieve conversion X. 11

12. Steady State 12

13. PFR volume necessary to achieve conversion X. Integrating 13

14. ReactorDifferentialAlgebraicIntegral CSTR PFR Batch X t PBR X W 14

15. Reactor Sizing Given –r A as a function of conversion, -r A = f(X), one can size any type of reactor. We do this by constructing a Levenspiel plot. Here we plot either (F A0 /-r A ) or (1/-r A ) as a function of X. For (F A0 /-r A ) vs. X, the volume of a CSTR and the volume of a PFR can be represented as the shaded areas in the Levenspiel Plots shown as: 15

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17. F A 0  r A Area = Volume of CSTR  X 1 17

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20. Numerical Evaluations of Integrals The integral to calculate the PFR volume can be evaluated using method as Simpson’s One-Third Rule: (See Appendix A.4) 20 Other numerical methods are: Trapezoidal Rule (uses two data points) Simpson’s Three-Eight’s Rule (uses four data points) Five-Point Quadrature Formula

21. Given: r A as a function of conversion, one can also design any sequence of reactors in series by defining X: Only valid if there are no side streams. Molar Flow rate of species A at point i: 21

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23. Reactor 1: V1V1 23

24. Reactor 2: V2V2 24

25. Reactor 3: V3V3 25

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27. Space time τ is the time necessary to process 1 reactor volume of fluid at entrance conditions. 27

28. KEEPING UP The tower of CRE, is it stable? 28

29. Reaction Engineering Mole BalanceRate LawsStoichiometry These topics build upon one another. 29

30. Mole Balance Rate Laws Stoichiometry Isothermal Design Heat Effects 30 CRE Algorithm

31. Mole Balance 31 Be careful not to cut corners on any of the CRE building blocks while learning this material! Rate Laws

32. Mole Balance Rate Laws Stoichiometry Isothermal Design Heat Effects 32 Otherwise, your Algorithm becomes unstable.

33. End of Lecture 2 33