1. Mustafa Nasser, PhD, MSc, BSc Chemical Engineering
CHE402: Kinetics and Reactor Design CHAPTER TWO Conversion and Reactor Sizing
Mustafa Nasser, PhD, MSc, BSc
Chemical Engineering
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2. Reaction Conversion Consider the general reaction;
on a “per mole of A basis”…
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3. Reaction Conversion The conversion of A (XA) is defined as:
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4. Conversion (Batch System)
Consider the batch reactor mole balance:
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5. Batch Reactor Design Equation
Recall the batch reactor design equation
differential form
integral form
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6. Conversion (Flow System)
Consider the flow reactor mole balance:
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7. CSTR Design Equations Recall the CSTR Design Equation:
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8. PFR Design Equations Recall the PFR Design Equation: differential form
integral form
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9. Application of Design Equations
Consider a single reaction system with functional dependence as;
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10. Application of Design Equations: Levenspiel Plots
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11. Application of Design Equations
For the CSTR;
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12. Application of Design Equations
For the PFR;
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13. Comparison PFR always requires less volume than a
CSTR to achieve a given conversion.
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14. CSTRs in Series FA,0 FA,1 X1 V2 V1 FA,2 X2
Where the conversion for successive reactors is defined as:
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15. PFRs in Series V1
FA,0
FA,1 X1 V2
FA,2 X2
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16. CSTRs in Series Finally consider a number of CSTRs in series:
Reactor 1:
Reactor 2: X
We see that we approach the PFR reactor volume for a large number of CSTRs in series:
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17. Reactors in Series FA,0 V2 V1 V3 FA,1 X1 FA,2 X2 FA,3 X3
Where the conversion for successive reactors is defined as:
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18. Reactors in Series FA,0 V2 V1 V3 FA,1 X1 FA,2 X2 FA,3 X3
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19. Reactors in Series FA,0 V2 V1 V3 FA,1 X1 FA,2 X2 FA,3 X3
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20. Reactors in Series FA,0 V2 V1 V3 FA,1 X1 FA,2 X2 FA,3 X3
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21. Reactors in Series FA,0 V2 V1 V3 FA,1 X1 FA,2 X2 FA,3 X3 V3 V2 V1 X1
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22. Numerical Evaluation of Integrals (Appendix A.4)
he integral to calculate the PFR volume can be evaluated using a method such as Simpson's One-Third Rule (page 1014)
Simpson's One-Third Rule is one of the more common numerical methods. It uses three data points. Other numerical methods (see Appendix A, pp ) for evaluating integrals are:
Trapezoidal Rule (uses two data points)
Simpson's Three-Eighth's Rule (uses four data points)
Five-Point Quadrature Formula
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23. Relative Reaction Rates
Relative reaction rates of the species involved in a reaction can be obtained from the stoichiometric coefficients:
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24. Space Time ()
Time necessary to process 1 reactor volume of fluid at entrance conditions
Also called residence time or holding time
1/ is referred to as the Space Velocity
For a PFR,
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27. (a): V= 6.4 m3 = 6400 = dm3 = 6400l
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30. (a)
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31. (b)
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32. (c)
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37. Solution 2-7
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38. Read the discussion 2.5.4
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39. Try This:
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