L8-1
Review: Pressure Drop in PBRs
A B
-rA = kCA
1st order reaction rate
dXA/dW for an isothermal ideal gas phase reaction with P
dX A
FA0
r ' A
Mole balance
dW
Rate law
r ' kC 2
A
Stoichiometry (put CA in
terms of X)
A
CA0 1 X A P
CA
1 X A P0
0
L3-1
Review: Batch Reactor Basic Molar Balance
No material enters or leaves the reactor
In ideal reactor, composition and temperature are spatially
uniform (i.e. perfect mixing)
No flow in or out of reactor. Fj0 and Fj = 0.
Rate of generation of reacta
L3b-1
Announcements
HW2 is due in class on Wednesday Sept 7th
No class on Monday in observance of Labor Day
If you need help, please attend the office hrs that are listed on the syllabus
Office hrs are canceled if no one shows up to the first 15 min
If y
L9b-1
Review: Analysis of Rate Data
Goal: determine reaction order, , and specific reaction rate constant, k
Data collection is done in the lab so we can simplify BMB, stoichiometry,
and fluid dynamic considerations
Want ideal conditions well-mixed (dat
L12-1
Review: Thermochemistry for
Nonisothermal Reactor Design
FA0
XA = 0.7
FA
Consider an exothermic, liquid-phase reaction operated adiabatically in a
PFR (adiabatic operation- temperature increases down length of PFR):
k
dX A rA
Mole balance:
dV FA0
Ra
L2b: Reactor Molar Balance
Example Problems
Fj0
Gj
L2b-1
Fj
reactor
Today we will use BMB to derive
reactor design equations. Your
goal is to learn this process, not
to memorize the equations!
Slides courtesy of Prof M L Kraft, Chemical & Biomolecular Eng
L4-1
Review: Design Eq & Conversion
b
c
d
A B C D
a
a
a
BATCH
SYSTEM:
XA
j stoichiometric coefficient;
positive for products, negative
for reactants
moles A reacted
moles A fed
N j N j0 jNA 0 X A
NT N j NT 0
j
XA
dX A
Ideal Batch Reactor
NA 0
rA V
Design
L7b-1
Review: Fixed-Volume CSTR Start-Up
Isothermal (unusual, but simple case), well-mixed CSTR
Unsteady state: concentrations vary with time & accumulation is non-zero
Goal: Determine the time required to reach steady-state operation and
CA as a function
L5-1
Review: Derive rA = f(XA)
Relate all
rj to Cj
rj
j
r A
Batch:
Relate all
Cj(XA) to
V()
Cj
Nj
V
Batch:
j stoichiometric coefficient
for products, for reactants
N j0 jNA0 X A
V
Flow:
Cj
Fj
Fj0 jFA0 X A
Flow:
Z T P0
P0 T Z
V
V
1
X
1
X
Relate al
L6-1
Review: Logic of Isothermal Reactor Design
1. Set up mole balance for
specific reactor
2. Derive design eq. in
terms of XA for each
reactor
3. Put Cj is in terms of
XA and plug into rA
(We will always look
conditions where Z0=Z)
In - Out +Generation
L4b-1
Review: Reaction Rates and Rate Laws
Reaction rate is a function of temperature and concentration
Elementary reaction
Involves only 1 step and proceeds as written
Stoichiometric coefficients in an elementary reaction are identical to
the powers
L2-1
Review: What size reactor(s) to use?
Answers to this questions are based on the desired
conversion, selectivity and kinetics
Reactor type
&
size
Kinetics
Material &
energy
balances
Conversion
&
selectivity
Slides courtesy of Prof M L Kraft, Chemical
L1-1
CHBE 424:
Chemical Reaction Engineering
Introduction & Lecture 1
Slides courtesy of Prof M L Kraft, Chemical & Biomolecular Engr Dept, University of Illinois, Urbana-Champaign.
L1-2
What is Chemical Reaction Engineering
(CRE) ?
Understanding how chem
L3b-1
Review: Design Eq & Conversion
b
c
d
A B C D
a
a
a
BATCH
SYSTEM:
XA
j stoichiometric coefficient;
positive for products, negative
for reactants
moles A reacted
moles A fed
N j N j0 jNA 0 X A
NT N j NT 0
j
XA
dX A
Ideal Batch Reactor
NA 0
rA V
Desig
L2b-1
Announcements
HW1 is due now (submit in class)
No class next Monday 9/5- Labor Day
HW2 is due at the start of class on WEDNESDAY 9/7
Office hour reminder- if no one attends the office hour during the 1st 15
minutes, the instructor or TA will leave a
L2-1
Announcements
Office hours for Prof Kraft are 5 6 pm Thursday, location TBD
Office hours for TA Sayani are 4 5 pm Thursday, location TBD
Office hours for Syeda are 4 5 pm Wednesday, location TBD
If no one attends the office hour during the 1st 15 min
L3-1
Announcements
HW2 is due at the start of class on Wednesday 9/7
No class on Monday 9/5- Labor Day
Attend office hours if you need help on the HW
If no one attends the office hour during the 1st 15 minutes, the
instructor or TA will not remain in
L9-1
Review: Isothermal Reactor Design
1. Set up mole balance for
specific reactor
2. Derive design eq. in
terms of XA for each
reactor
3. Put Cj is in terms of
XA and plug into rA
(We will always look
conditions where Z0=Z)
In - Out +Generation = Accumul
L7-1
Be able to do these 4 steps,
integrate & solve for V for ANY
ORDER RXN
Review: Liquid Phase Reaction in PFR
LIQUID PHASE: Ci f(P) no pressure drop
2A B -rA = kCA2 2nd order reaction rate
Calculate volume required to get a conversion of XA in a PFR
dX
Name _ Quiz Section _ page 1 of 15
ChBE 221
Principles of Chemical Engineering | Final Exam
100 Gregory Hall | December 15, 2012
1:40-3:10 p.m.
No work written on the back of pages will be graded
This book is closed notes & closed book, you may bring a si
ChBE221 | Final Exam | December 15, 2012 page 1 of 10
ChBE221 | Final Exam | December 15, 2012
Problem 1
Let variables in the new units be labeled with a prime
Thus T [=] oC, P [=] kPa, and L [=] N per 1000 m3 of gas
Prepare substitutions
T = 1.8T + 32 [C
1 of 4
Notes for Lecture Review Exam 02 Fall 2013 ChBE221
The frequency of the question is in parenthesis (e.g. 51 people asked a similar question for the first
bullet point below.)
Format/What will be on the exam?
What will be the biggest topic for this