CRE is the field that studies the rates and mechanisms of chemical reactions and the design of the reactors in which they take place Lecture 2 1 Todays lecture Review of Lecture 1 Solution to ID: 652082
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Slide1
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.
Lecture 2
1Slide2
Today’s lecture
Review of Lecture 1Solution to P1-6Definition of Conversion, X
Develop the Design Equations in Terms of X
Size CSTRs and PFRs given –
rA= f(X)Conversion for Reactors in SeriesReview the Fall of the Tower of CRE
2Slide3
Reactor Mole Balance Summary
Reactor
Differential
Algebraic
Integral
CSTR
Batch
N
A
t
PFR
F
A
V
3Slide4
Homework
Problem Solution
4
Liquid
phase
Given the following information, Find VSlide5
(1) Mole
Balance:
(2) Rate Law:
(3)
Stoichiometry
:
5Slide6
(4) Combine:
(5) Evaluate:
6Slide7
Consider the generic reaction
7Slide8
Batch
8Slide9
Batch
Integrating
The necessary
t
to achieve conversion X.
9Slide10
CSTR
Steady
State
10Slide11
Well
Mixed
CSTR
CSTR
volume
necessary
to
achieve conversion X. 11Slide12
Steady
State
PFR
12Slide13
This is the PFR volume necessary to achieve conversion X.
PFR
Integrating
13Slide14
Reactor Mole
Balances in terms of conversion
Reactor
Differential
Algebraic
Integral
CSTR
PFR
Batch
X
t
PBR
X
W
14Slide15
Levenspiel Plots
Reactor Sizing
Given –r
A
as a function of conversion, -rA= f(X), one can size any type of reactor. We do
this by
constructing
a
Levenspiel plot. Here we plot either (FA0/-rA) or (1/-rA) as a function of X. For (FA0/-rA) vs. X, the volume of a CSTR and the volume of a PFR can be represented as the shaded areas in the Levenspiel Plots shown as:15Slide16
Levenspiel Plots
16Slide17
Numerical Evaluations of Integrals
The integral to calculate the PFR volume can be evaluated using method as Simpson’s One-Third Rule: (See Appendix A.4)Other numerical methods are:
Trapezoidal Rule (uses two data points)
Simpson’s
Three-Eight’s Rule (uses
four
data points)
Five-Point Quadrature Formula17Slide18
Reactors in Series
Given: rA as a function of conversion, one can also design any sequence of reactors:
Only
valid
if
there
are no
side streams.Molecule Flow rate of species A at point i: 18Slide19
Reactors in Series
19Slide20
Reactors in Series
Reactor 1:
20
V
1Slide21
Reactors in Series
Reactor 2:
21
V
2Slide22
Reactors in Series
Reactor 3:
22
V
3Slide23
Reactors in Series
23Slide24
Reactors in Series
Space time τ is the time necessary to process 1 reactor volume of fluid at entrance conditions.
24Slide25
KEEPING UP
The tower of CRE, is it stable?
25Slide26
Reaction Engineering
These topics build upon one another
Mole Balance
Rate Laws
Stoichiometry
26Slide27
Mole Balance
Rate Laws
Stoichiometry
Isothermal Design
Heat Effects
27Slide28
Mole Balance
Rate Laws
28Slide29
Mole Balance
Rate Laws
Stoichiometry
Isothermal Design
Heat Effects
29Slide30
End of Lecture 2
30