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Lecture 21

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Lecture 21

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.

- CSTR With Heat Effects
- Multiple Steady States
- Ignition and Extinction Temperatures

Courtesy of Pfaudler, Inc.

Neglect

Using

Unsteady State Energy balance

We obtain after some manipulation:

Collecting terms with and high coolant flow rates,and

If G(T) > R(T) TemperatureIncreases

If R(T) > G(T) TemperatureDecreases

At Steady State

Solving for X.

Solving for X

Solving for T

Increasing T0

R(T)

Variation of heat removal line with inlettemperature.

T

Energy balance for CSTRs

κ=∞

R(T)

κ=0

T0

Increase κ

Ta

T

Variation of heat removal line with κ (κ=UA/CP0FA0)

1) Mole Balance:

2) Rate Law:

3) Stoichiometry:

4) Combine:

Multiple Steady States (MSS)

Variation of heat generation curve with space-time.

Multiple Steady States

Finding Multiple Steady States with T0 varied

Multiple Steady States

Finding Multiple Steady States with T0 varied

Multiple Steady States

Temperature ignition-extinction curve

Multiple Steady States

Stability of multiple state temperatures

MSS - Generating G(T) and R(T)

Need to solve for X after combining mole balance rate law and stoichiometry.

MSS - Generating G(T) and R(T)

For a first order irreversible reaction

Parameters

Thenplot G and R as a function of T.