Lecture 1

1 - 02/16/19
DepartmentofChemicalEngineering
Professor De Chen
Institutt for kjemisk prosessteknologi, NTNU
Gruppe for katalyse og petrokjemi
Kjemiblokk V, rom 407
chen@nt.ntnu.no

2 - 02/16/19
Kjemisk reaksjonsteknikk
Chemical Reaction Engineering
H. Scott Fogler: Elements of Chemical Engineering
www.engin.umich.edu/~cre
University of Michigan, USA
Time plan:
Week 34-47, Tuesday: 08:15-10:00
Thursday: 11:15:13:00
Problem solving: Tuseday:16:15-17:00

3 - 02/16/19

4 - 02/16/19
 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.

5 - 02/16/19
Lecture notes will be published on It’s
learning after the lecture
(Pensumliste ligger på It’s learning
Deles ut på de første forelesningene)
Øvingsopplegget ligger på It’s learning
Deles ut på de første forelesningene

6 - 02/16/19
Felleslaboratorium
Faglærer: Professor Heinz Preisig
For information: It’s learning
Introduction lecture:
Place : in PFI-50001, the lecture room on the
top of the building
Date: Tuesday 21 of August
Time: 12:15 - 14:00

7 - 02/16/19
TKP4110 Chemical Reaction Engineering
Øvingene starter onsdag 26 august kl 1615
i K5.
Lillebø, Andreas Helland: andreas.lillebo@chemeng.ntnu.no
Stud.ass.:
Kristian Selvåg : krisse@stud.ntnu.no
Øyvind Juvkam Eraker: oyvindju@stud.ntnu.no
Emily Ann Melsæther: melsathe@stud.ntnu.no

8 - 02/16/19
Lecture 1
1.Industrial reactors
2.Reaction engineering
3.Mass balance
4.Ideal reactors

9 - 02/16/19
Steam Cracking (Rafnes)

10 - 02/16/19
DepartmentofChemicalEngineering Batch reactor

11 - 02/16/19
DepartmentofChemicalEngineering Fixed bed reactor

12 - 02/16/19
CSTR bioreactor

13 - 02/16/19
DepartmentofChemicalEngineering Artificial leaf, photochemical reactor

14 - 02/16/19
Chemical Engineering
Reaction
engineering
Mass
transfer
Heat
transfer
Momentum
transfer

15 - 02/16/19

16 - 02/16/19
Reaction Engineering
Mole Balance Rate Laws Stoichiometry
These topics build upon one another
16

17 - 02/16/19
Mole Balance
Rate Laws
Stoichiometry
Isothermal Design
Heat Effects
17
No-ideal flow

18 - 02/16/19
Chemical kinetics and reactor design
are at the heart of
producing almost all industrial chemicals
It is primary a knowledge of
chemical kinetics and reactor design that
distinguishes
the chemical engineer from other
engineers

19 - 02/16/19
1. Week 34, Aug. 21, chapter 1, Introduction, mole balance, and ideal
reactors,
2. Week 34, Aug. 23, chapter2, Conversion and reactor size
3. Week 35, Aug. 28, chapter 3, Reaction rates
4. Week 35, Aug. 30, chapter 3, Stoichometric numbers
5. Week 36, Sept. 4, chapter 4, isothermal reactor design (1)
6. Week 36, Sept. 6, chapter 4, isothermal reactor design (2)
7. Week 37, Sept. 11, chapter 10, catalysis and kinetics (1)
10.Week 38, Sept. 20, chapter 5,7, kinetic modeling (1)
11.Week 39, Sept. 25, chapter 5,7, kinetic modeling (2)
12.Week 39, Sept. 28 chapter 6, multiple reactions (1)
13.Week 40, Oct. 2, chapter 6 multiple reactions (2)
14.Week 40, Oct. 4, summary of chapter 1-7, and 10

20 - 02/16/19
 41 (9/10, 11/10) 8.1 - 8.2 (JPA) Reaktorberegninger for ikke-isoterme systemer.
 42 (16/10, 18/10) 8.3 – 8.5 (JPA) Energibalanser, stasjonær drift. Omsetning ved
likevekt. Optimal fødetemperatur.
 43 (23/10, 25/10) 8.6 - 8.7 (JPA) CSTR med varmeeffekter og flere løsninger ved
stasjonær drift, ustabilitet.

 44 (30/10, 1/11) 11 (JPA) Masseoverføring, ytre diffusjonseffekter i
heterogene systemer.

 45 (6/11, 8/11) 11 (JPA) Fylte reaktorer (packed beds). Kjernemodellen
(shrinking core). Oppløsning av partikler og
regenerering av katalysator.
 46 (13/11, 15/11) 12.1-12.4 (JPA) Diffusjon og reaksjon i katalysatorpartikler,
Thieles modul, effektivitetsfaktor.
 47 (20/11,22/11) 12.5-12.8 (JPA) Masseoverføring og reaksjon i flerfasereaktorer.
Oppsummering.
 50 (Mandag 13/12) Eksamen, kl 0900-1300.

21 - 02/16/19
Chemical Identity and reaction
 A chemical species is said to have reacted when it
has lost its chemical identity. There are three ways
for a species to loose its identity:
1. Decomposition CH3CH3  H2 + H2C=CH2
2. Combination N2 + O2  2 NO
3. Isomerization C2H5CH=CH2  CH2=C(CH3)2
21

22 - 02/16/19
Reaction Rate
 The reaction rate is the rate at which a species
looses its chemical identity per unit volume.
 The rate of a reaction (mol/dm3
/s) can be
expressed as either:
The rate of Disappearance of reactant: -rA
or as
The rate of Formation (Generation) of product: rP
22

23 - 02/16/19
Reaction Rate
Consider the isomerization
A  B
rA = the rate of formation of species A per unit
volume
-rA = the rate of a disappearance of species A per unit
volume
rB = the rate of formation of species B per unit
volume
23

24 - 02/16/19
Reaction Rate
 For a catalytic reaction, we refer to -rA', which is
the rate of disappearance of species A on a per
mass of catalyst basis. (mol/gcat/s)
NOTE: dCA/dt is not the rate of reaction
24

25 - 02/16/19
Reaction Rate
Consider species j:
1.rj is the rate of formation of species j per unit
volume [e.g. mol/dm3
s]
2.rj is a function of concentration, temperature,
pressure, and the type of catalyst (if any)
3. rj is independent of the type of reaction system
(batch, plug flow, etc.)
4.rj is an algebraic equation, not a differential
equation
(e.g. = -rA = kCA or -rA = kCA
2
)
25

26 - 02/16/19
General Mole Balance






=





+





−





=+−










=










+










−










time
mole
time
mole
time
mole
time
mole
dt
dN
GFF
jSpeciesof
onAccumulati
RateMolar
jSpeciesof
Generation
RateMolar
outjSpecies
ofRate
FlowMolar
injSpecies
ofRate
FlowMolar
j
jjj0
Fj0 FjGj
System
Volume, V
26

27 - 02/16/19
If spatially uniform
Gj =rjV
If NOT spatially uniform
2V∆
rj2
Gj1=rj1∆V1
Gj2=rj2∆V2
1V∆
rj1
27

28 - 02/16/19
Gj = rji∆Vi
i=1
W
∑
Gj =
lim∆V→0 n→∞
rji∆Vi
i=1
n
∑ = rjdV∫
Take limit
28

29 - 02/16/19
General Mole Balance on System Volume V
In −Out + Generation = Accumulation
FA0−FA + rA∫ dV =
dNA
dt
FA0 FAGA
System
Volume, V
29

30 - 02/16/19
Batch Reactor Mole Balance
FA0 −FA + rA∫ dV=
dNA
dt
FA0 =FA =0
dNA
dt
=rAV
Batch
VrdVr AA =∫Well Mixed
30

31 - 02/16/19
dt =
dNA
rAV
Integrating
Time necessary to reduce number of moles of A from NA0 to NA.
when t = 0 NA=NA0
t = t NA=NA
∫ −
=
A
A
N
N A
A
Vr
dN
t
0
31

32 - 02/16/19
∫ −
=
A
A
N
N A
A
Vr
dN
t
0
NA
t32

33 - 02/16/19
CSTR Mole Balance
FA0−FA + rA∫ dV=
dNA
dt
dNA
dt
=0Steady State
CSTR
33

34 - 02/16/19
FA0−FA+rAV=0
V=
FA0 −FA
−rA
VrdVr AA =∫Well Mixed
CSTR volume necessary to reduce the molar flow rate from FA0 to
FA.
CSTR Mole Balance
34

35 - 02/16/19
Plug Flow Reactor Mole Balance
∆V
V VV ∆+
FA
FA
0
0
=∆+−
=





∆
+





∆+
−





∆+
VrFF
Vin
Generation
VVat
Out
Vat
In
AVVAVA
35

36 - 02/16/19
lim
∆V→0
FAV+∆V
−FAV
∆V
=rA
Rearrange and take limit as VΔ 0
dFA
dV
=rA
36
This is the volume necessary to reduce the entering molar flow rate
(mol/s) from FA0 to the exit molar flow rate of FA.

37 - 02/16/19
Alternative Derivation –
00 =+− ∫ dVrFF AAA
0=
dt
dNA
Steady State
dt
dN
dVrFF A
AAA0 =+− ∫
PFR
37

38 - 02/16/19
dFA
dV
=rA
0−
dFA
dV
=−rA
Differientiate with respect to V
∫=
A
A
F
F A
A
r
dF
V
0
The integral form is:
This is the volume necessary to reduce the entering molar flow rate
(mol/s) from FA0 to the exit molar flow rate of FA.
Alternative Derivation –
38

39 - 02/16/19
( ) ( )
dt
dN
WrWWFWF A
AAA =∆′+∆+−
A
WAWWA
W
r
W
FF
′=
∆
−∆+
→∆ 0
lim
0=
dt
dNASteady State
PBR
Packed Bed Reactor Mole Balance
39

40 - 02/16/19
Packed Bed Reactor Mole Balance
dFA
dW
= ′rA
Rearrange:
PBR catalyst weight necessary to reduce the entering molar flow
rate FA0 to molar flow rate FA.
∫ ′
=
A
A
F
F A
A
r
dF
W
0
The integral form to find the catalyst weight is:
40

41 - 02/16/19
Reactor Mole Balance Summary
Reactor Differential Algebraic Integral
V=
FA0 −FA
−rA
CSTR
Vr
dt
dN
A
A
=
0
∫=
A
A
N
N A
A
Vr
dN
tBatch
NA
t
dFA
dV
=rA ∫=
A
A
F
F A
A
dr
dF
V
0
PFR
FA
V
41

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