CHEE 321: Chemical Reaction Engineering Module 6: Non-Isothermal Reactors (Chapter 8, Fogler)

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CHEE 321 Chemical Reaction EngineeringModule
6 Non-Isothermal Reactors (Chapter 8, Fogler)
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Topics to be covered in this Module

• Module 6a (Sections 8.2, 8.3, 8.4, 8.6.1
  Fogler, 4th Edition)
• Develop Energy Balance equations for flow
  reactors.
• Enthalpy, Heat Capacity, and Heat of Reaction and
  relationship between them
• Heat transfer rates for CSTR and PFR/PBR
• Algorithms for Non-isothermal CSTR and PFR
• Module 6b (Sections 8.5)
• Equilibrium Conversion (Reversible Reactions) in
  Reactors
• Conversion attainable during adiabatic operation
  of endothermic and exothermic reactors
• Increasing Conversion by inter-stage cooling and
  heating

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Sulphuric Acid Production
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H2SO4 Production Catalytic Converter
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Equilibrium for Single Reactions
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Chemical Equilibrium and Equilibrium Constant

• The equilibrium constant (K) is a function of
  temperature only and related to Gibbs free energy
  change for the reaction by the following
  relationship

The gibbs free energy change for a reaction can
be calculated from gibbs free energy of formation
data and knowledge of stoichiometry
Consider, the Reaction
The Gibbs free energy change for the reaction can
be written as
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Temperature Dependence of Equilibrium Constant

• Vant Hoff Relationship for Kp and T
• (Appendix C of Fogler)

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Adiabatic Operation Equilibrium Conversion

• For a reactor operating adiabatically, the
  maximum conversion that may be achieved is the
  equilibrium conversion.
• How can we calculate this ?

Step-1 Calculate Xe as a function of T
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Adiabatic Operation Equilibrium Conversion

• Step-2 Calculate XEB as a function of
  Temperature from Steady State Energy Balance
  Equation

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Exothermic Reaction A Closer Look at Adiabatic
Conversion
Increasing the inlet temperature results in
shifting of the EB equation to the RIGHT
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Exothermic Reactions Achieving Higher Conversion
by Inter-stage Cooling
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Endothermic Reaction A Closer Look at Adiabatic
Conversion
Equilibrium
Increasing the inlet temperature results in
shifting of the EB equation to the RIGHT
Xe
X
EB
T
T01
T02
Adiabatic Temperature
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Endothermic Reactions Achieving Higher
Conversion by Inter-stage Heating