1. Chemical Reaction Engineering
Chapter 4, Part 1:
Applying the Algorithm to a CSTR

2. Summary
At the start of the chapter we saw we needed -rA=f(X). This result is achieved in two steps.
Rate Laws
-rA=k f(Ci)
1st order or 2nd order
Rate laws are found by experiment
Stoichiometry
Liquid:
Gas:
A + B  C
-rA=kCA
-rA=kACACB

3. (Level 1) General mole balance
Ch. 1
(Level 1) General mole balance
(Level 9)
Find
appropriate
design
Equation
Ch.2
(Level 2) Design Equation for specific reactor
IS –rA=f(X)
given
Ch.2
(Level 3)
(level 4) determined the Rate law in terms of concentration
Ch.3
Ch.4
Ch.4
(level 5) use stoichiometry to express concentration as function of X
(level 6) if gas with P=P0 or Liquid
Ch.3
(level 7) Determine the pressure drop in the reactor
(level 8) Combine the equation of pressure drop with level 4,5
Ch.4

4. Algorithm for Isothermal Reactor Design
Mole Balance and Design Equation
Choose species reacting and the reactor
Rate Law
Identify the reaction order and reaction parameters
Stoichiometry
Choose the reaction phase and concentrations
Combine
Step 1, 2 & 3
Evaluate
Analytical, Graphical, Numerical and Using Software

7. French Menu Analogy Example: Mole Balance: Rate Law: Stoichiometry:
The elementary gas phase reaction takes place in a CSTR at constant temperature (500 K) and constant pressure (16.4 atm). The feed is equal molar in A and B.
Stoichiometry:
Mole Balance:
Rate Law:
gas phase, isothermal (T=T0), no pressure drop (P=P0)

8. French Menu Analogy For a gas phase system:
If the conditions are isothermal (T = T0) and isobaric (P =P0):
We must divide by the stoichiometric coefficient of our basis of calculation yielding:
And if the feed is equal molar, then:

9. French Menu Analogy
This leaves us with CA as a function of conversion alone:
Similarly for CB:

10. French Menu Analogy
Combine:
Evaluate: