lecture 5 kjemisk reaksjonsteknikk chemical reaction engineering
Post on 19-Jan-2016
53 Views
Preview:
DESCRIPTION
TRANSCRIPT
1 - 04/21/23
Departm
ent of Chem
ical E
ngineering
Lecture 5
Kjemisk reaksjonsteknikk
Chemical Reaction Engineering
Isothermal reaction design algorithm Algorithm to estimate the time or conversion for
different reactor Examples
2 - 04/21/23
Departm
ent of Chem
ical E
ngineering
These topics build upon one another
Mole
Bala
nce
Rate
Law
s
Sto
ich
iom
etr
y
Reaction Engineering
2
Isothermal reactor design
3 - 04/21/23
Departm
ent of Chem
ical E
ngineering
For Gas Phase Flow Systems
0
00
0
00
0
11 P
P
T
T
X
XC
PP
TT
X
XFFC jjAjjAjj
Cj=f(Fj, T, P) =f(x, T,P)
Da
dC
a
cB
a
bA
νj stochiomentric number, b/a, c/a, d/a
Isothermal T=T0
Liquid phase: ε=0
4 - 04/21/23
Departm
ent of Chem
ical E
ngineering
4
5 - 04/21/23
Departm
ent of Chem
ical E
ngineering
5
6 - 04/21/23
Departm
ent of Chem
ical E
ngineering
6
7 - 04/21/23
Departm
ent of Chem
ical E
ngineering
Batch reactor
1) Mole balance
AA kCr
Vrdt
dXN A0A
1
1ln
1
xkt
2) Rate law
X
tFirst-order Second-order
22 AA Ckr
3) Stoichiometry: X1CC 0AA
4) Combine: Xkdt
dx 1 2
02 1 XCkdt
dxA
5. Evaluation)1(02 xCk
xt
A
)exp(1 1tkx 02
02
1 A
A
Ctk
Ctkx
8 - 04/21/23
Departm
ent of Chem
ical E
ngineering
CSTR reactor
1) Mole balance
AA kCr 2) Rate law First-order Second-order
22 AA Ckr
3) Stoichiometry: XFF AA 10
4) Combine:
)1(0
0
xkC
xCV
A
A
5. Evaluation
k
kx
1
A
0A
r
XFV
X1CX1FF
C 0A0
0AAA
20 )1( xkC
xV
A
0
00
2
4121
A
AA
kC
kCkCx
9 - 04/21/23
Departm
ent of Chem
ical E
ngineering
PFR reactor
1) Mole balance
AA kCr 2) Rate law First-order Second-order
22 AA Ckr
3) Stoichiometry: XFF AA 10
4) Combine:
5. Evaluation
xx
k
1
1ln
A0A rdV
dXF
X1
X1CC 0A
A
2
202
1
1
)/( X
XCk
Vd
dx A
X1
X1XX1ln12kC
22
0A
X
Xk
Vd
dx
1
1
)/(
10 - 04/21/23
Departm
ent of Chem
ical E
ngineering
Examples:
Liquid Phase Laboratory Experiment(CH2CO)2O + H2O 2CH3COOH
A + B 2CEnteringVolumetric flow rate v0 = 0.0033 dm3/sAcetic Anhydride 7.8% (1M)Water 92.2% (51.2M)Elementary with k’ 1.95x10-4 dm3/(mol.s)
Case I CSTR V = 1dm3
Case II PFR V = 0.311 dm3
10
11 - 04/21/23
Departm
ent of Chem
ical E
ngineering
Part 1: Mole Balances in Terms of Conversion
Algorithm for Isothermal Reactor Design
1. Mole Balance and Design Equation
2. Rate Law
3. Stoichiometry
4. Combine
5. Evaluate
A. Graphically (Chapter 2 plots)
B. Numerical (Quadrature Formulas Chapter 2 and appendices)
C. Analytical (Integral Tables in Appendix)
D. Software Packages (Appendix- Polymath)
11
12 - 04/21/23
Departm
ent of Chem
ical E
ngineering
CSTR Laboratory Experiment
Example: CH3CO2 + H20 2CH3OOH
1) Mole Balance: CSTR:A
0A
r
XFV
M2.51C 0B
M1C 0A
?X
V 1 dm3
0 3.310 3 dm3
s
12
A + B 2C
13 - 04/21/23
Departm
ent of Chem
ical E
ngineering
1) Rate Law:BAAA CCkr
1) Stoichiometry:
B FA0ΘB -FA0X FB=FA0(ΘB-X)
A FA0 -FA0X FA=FA0(1-X)
C 0 2FA0X FC=2FA0X
CSTR Laboratory Experiment
13
14 - 04/21/23
Departm
ent of Chem
ical E
ngineering
X1CX1FF
C 0A0
0AAA
XCXF
C B0A0
B0AB
2.511
2.51B
0B0A0AB C2.51CX2.51CC
CSTR Laboratory Experiment
14
15 - 04/21/23
Departm
ent of Chem
ical E
ngineering
X1kCX1C
k
C'kr 0A0A0BA
k1
kX
75.003.4
03.3X
CSTR Laboratory Experiment
15
V
0
kCA 0XC
A0 1 X V0
X1 X V
0
kX1 X k
16 - 04/21/23
Departm
ent of Chem
ical E
ngineering
PFR Laboratory Experiment
X
0.311 dm3
1) Mole Balance:0A
A
F
r
dV
dX
2) Rate Law:BAA CkCr
3) Stoichiometry: X1CC 0AA
0BB CC 16
A + B 2C
17 - 04/21/23
Departm
ent of Chem
ical E
ngineering
PFR Laboratory Experiment
4) Combine: X1kCX1CC'kr 0A0A0BA
kddVk
X1
dX
C
X1kC
dV
dX
0
00A
0A
kX1
1ln
ke1X
sec 94 1s 01.0k
61.0X 17
4) Combine: X1kCX1CC'kr 0A0A0BA
18 - 04/21/23
Departm
ent of Chem
ical E
ngineering
Examples:Gas Phase : PFR and Batch Calculation 2NOCl 2NO + Cl2
2A 2B + C
Pure NOCl fed with CNOCl,0 = 0.2 mol/dm3 follows an
elementary rate law with k = 0.29 dm3/(mol.s)
Case I PFR with v0 = 10 dm3/sFind space time, with X = 0.9 Find reactor volume, V for X = 0.9
Case II Batch constant volumeFind the time, t, necessary to achieve 90% conversion.
Compare and t.
18
19 - 04/21/23
Departm
ent of Chem
ical E
ngineering
Example (Gas Flow, PFR)
2 NOCl 2 NO + Cl2
s
dm 10
3
0 smol
dm29.0k
3
L
mol2.0C 0A
0TT
P P0
X 0.9
1) Mole Balance:0A
A
F
r
dV
dX
2) Rate Law: 2AA kCr
19
2A 2B + C
20 - 04/21/23
Departm
ent of Chem
ical E
ngineering
Example (Gas Flow, PFR)
3) Stoich: Gas X10
4) Combine: 2
220A
AX1
X1kCr
X1
X1CC 0A
A
A B + C/2
DakC
VkCdV
kCdX
X1
X1
X1C
X1kC
dV
dX
0A0
0AV
0 0
0AX
02
2
200A
220A
20
Damköhler number
21 - 04/21/23
Departm
ent of Chem
ical E
ngineering
Example (Gas Flow, PFR)
X1
X1XX1ln12kC
22
0A
2
1
2
11y 0A
02.17kC 0A
sec 294kC
02.17
0A
L 2940VV 0 21
22 - 04/21/23
Departm
ent of Chem
ical E
ngineering
Example Constant Volume (Batch)
1) Mole Balance:0A
A
00A
A
0A
0A
C
r
VN
r
N
Vr
dt
dX
2) Rate Law: 2AA kCr
X1CV
X1NC 0A
0
0AA
220AA X1kCr
3) Stoich: Gas 0VV 0
V
22
Gas Phase 2A 2B + C
23 - 04/21/23
Departm
ent of Chem
ical E
ngineering
Example Constant Volume (Batch)
20A
0A
220A X1kCC
X1kC
dt
dX
4) Combine:
dtkC
X1
dX0A2
tkCX1
10A
sec 155t
20A X1kC
d
dX
23
top related