310 likes | 497 Vues
Chemical Reaction Engineering Asynchronous Video Series. Chapter 4, Part 1: Applying the Algorithm to a CSTR H. Scott Fogler, Ph.D. Summary. At the start of the chapter we saw we needed -r A =f(X). This result is achieved in two steps. Rate Laws -r A =k f(C i )
E N D
Chemical Reaction EngineeringAsynchronous Video Series Chapter 4, Part 1: Applying the Algorithm to a CSTR H. Scott Fogler, Ph.D.
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 A--> B or 1st order • 2nd order A+B --> C • Rate laws are found by experiment • Stoichiometry • Liquid: • Gas: -rA=kCA -rA=kACACB
Algorithm for Isothermal Reactor Design • Mole Balance and Design Equation • Rate Law • Stoichiometry • Combine • Evaluate
Algorithm for Isothermal Reactor Design • Mole Balance and Design Equation • Rate Law • Stoichiometry • Combine • Evaluate The Evaluate step can be carried out:
Algorithm for Isothermal Reactor Design • Mole Balance and Design Equation • Rate Law • Stoichiometry • Combine • Evaluate • The Evaluate step can be carried out: • Graphically (Chapter 2 plots)
Algorithm for Isothermal Reactor Design • Mole Balance and Design Equation • Rate Law • Stoichiometry • Combine • Evaluate • The Evaluate step can be carried out: • Graphically (Chapter 2 plots) • Numerically (Quadrature formulas: Chapter 2 and Appendices)
Algorithm for Isothermal Reactor Design • Mole Balance and Design Equation • Rate Law • Stoichiometry • Combine • Evaluate • The Evaluate step can be carried out: • Graphically (Chapter 2 plots) • Numerically (Quadrature formulas: Chapter 2 and Appendices) • Analytically (Integral tables in Appendix)
Algorithm for Isothermal Reactor Design • Mole Balance and Design Equation • Rate Law • Stoichiometry • Combine • Evaluate • The Evaluate step can be carried out: • Graphically (Chapter 2 plots) • Numerically (Quadrature formulas: Chapter 2 and Appendices) • Analytically (Integral tables in Appendix) • Software packages (Appendix - Polymath)
French Menu Analogy Example: 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.
French Menu Analogy Example: 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. Mole Balance:
French Menu Analogy Example: 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. Mole Balance: Rate Law:
French Menu Analogy Example: 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. Mole Balance: Rate Law: Stoichiometry: gas phase, isothermal (T=T0), no pressure drop (P=P0)
French Menu Analogy Deriving CA and CB: Remember the French Menu reaction: For a gas phase system:
French Menu Analogy Deriving CA and CB: Remember the French Menu reaction: For a gas phase system: If the conditions are isothermal (T = T0) and isobaric (P =P0):
French Menu Analogy Deriving CA and CB: Remember the French Menu reaction: 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:
French Menu Analogy Deriving CA and CB: Remember the French Menu reaction: 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:
French Menu Analogy Deriving CA and CB: This leaves us with CA as a function of conversion alone:
French Menu Analogy Deriving CA and CB: This leaves us with CA as a function of conversion alone: Similarly for CB:
French Menu Analogy Example: 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. Mole Balance: Rate Law: Stoichiometry: gas phase, isothermal (T=T0), no pressure drop (P=P0) [Why do you think CB is constant, when B is consumed?]
French Menu Analogy Example: 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. Mole Balance: Rate Law: Stoichiometry: gas phase, isothermal (T=T0), no pressure drop (P=P0) [Why do you think CB is constant, when B is consumed?]
French Menu Analogy Example: 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. Mole Balance: Rate Law: Stoichiometry: gas phase, isothermal (T=T0), no pressure drop (P=P0) [Why do you think CB is constant, when B is consumed?] Combine:
French Menu Analogy Example: 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. Mole Balance: Rate Law: Stoichiometry: gas phase, isothermal (T=T0), no pressure drop (P=P0) [Why do you think CB is constant, when B is consumed?] Combine: Evaluate: