Chapter 23
23.1 The main reason is the requirement for large reactors in order to obtain very high
conversions. If the reaction rates are very high for the conditions used (for example the
1:3.3:4.3:6.6:10
In addition, for high conversions the flow pattern and mixing in the reactor become
23.2 This statement is not necessarily true. If the reaction is at equilibrium, then according to
Le Chateliers principle – an increase in reaction temperature will lead to a decrease in
23.3 Since the reaction rate doubles for a temperature change from 250 C to 270 C, we may
write that
(a) For a change from 250 C to 260 C, we get
(b) Assuming that the feed composition is constant then the gas phase concentrations
increase by 15%
23-2
23.4 (a) The reaction is exothermic, since heat is removed after the first packed bed section.
(b) The reaction is run at high temperature because
23.5
A + B = C
As T , X
As P, X
23.6
aA bB
1
pP
2
uU
B
3
V
23-4
23.7 ACO k1DO AA
2DO k2Gum
23.8
C
2
40.5O2
C
2
4O
C
2H43O22CO22H2O
C2H4O2.5O22CO22H2O
E
E
23-5
23.9 (a) Countercurrent flow of HTM
T
Q
Q
23-6
23.10 (a) PB
C
APo r
x
F
W
2
2
5.01
1
x
x
kC
x
F
W
Po
Po
x2 = 0.63
P B C
1-x 1-x x
1x
10.5x 1x
10.5x x
10.5x
= 0.5
(b)
2
1
1
2
2
1
1
2
P
P
Po
Po
r
r
x
x
F
F
W
W
(c)
2
1
1
2
2
1
1
2
P
P
Po
Po
r
r
x
x
F
F
W
W
(d) 2
1
2
2
2
2
2
1
2
2
2
1
12
11
1
2
2
1
1
2
2
1
1
2
5.01
5.01
1
1
x
x
x
x
RTP
RTP
k
k
x
x
r
r
x
x
F
F
W
W
Po
Po
PA
P
Po
Po
23-8
23.11 0 0
x x
Ao Ao
A
A
dx dx
t N C
r v r
k
(a) t2
t1
k1
k2
ln 1 x2
ln 1 x1
ln 1 0.75
ln 1 0.50
t2
t1
2
(c) tCAo
dx
kCAo
21x2
1
kCAo
1
1x
0
x
0
x
1
kCAo
1
1x11
kCAo
x
1x
t1
kCAo
x
1x
(d) Since this is not a linear function, it takes much longer to approach 100%
conversion since approach is asymptotic.
23-9
Background Information on Problems 23.12-23.16  Production of Benzene
23.12 (see background information on page 23-9)
23-11
23.12 (contd)
Problem 23.12
23-12
23.13 (see background information on page 23-9 and Problem 23.12)
23-13
23.13 (contd)
23-14
23.14
23-15
23.14 (contd)
23-16
23-17
23.15 (contd)
23-18
23.16
23-19
23.16 (contd)