viii
TABLE OF CONTENTS
CHAPTER TITLE
1
2
PAGE
Title
i
Declaration
ii
Dedications
iii
Acknowledgement
iv
Abstract
vi
Abstrak
vii
Table of Content
viii
List of Tables
xii
List of Figures
xiv
List of Symbols
xvii
List of Appendices
xxi
INTRODUCTION
1
1.1 Process synthesis
1
1.2 Process integration and process synthesis
1
1.3 Problem statement
3
1.4 Objective
3
1.5 Scopes of research
3
1.6 Contributions of the work
4
1.7 Summary of this thesis
5
BACKGROUND THEORY AND LITERATURE
8
REVIEW
2.1 Introduction
8
ix
2.2 Synthesis of water network for continuous
processes
9
2.2.1 Types of water-using processes
2.2.2 Problem statement for water network
synthesis
9
12
2.2.3 Targeting tools for water network
2.2.4 Appropriate placement of water
regeneration unit
12
15
2.3 Synthesis of batch water network
2.3.1 Problem statement for batch water
network synthesis
17
17
2.3.2 Synthesis tools in batch water network
2.4 Synthesis of hydrogen network
2.4.1 Problem statement of hydrogen network
synthesis
18
19
20
2.4.2 Conceptual understanding of hydrogen
source and sink
20
2.4.3 Targeting tool for hydrogen network
2.4.4 Appropriate placement of hydrogen
purifiers
23
24
2.5 Synthesis of property-based network
2.5.1 Problem statement of property-based
network synthesis
25
26
2.5.2 The concept of property operator and
property load
27
2.5.3 Targeting tool for property-based network
30
2.5.4 Process modifications
31
2.6 Literature review
32
2.6.1 Synthesis of water network
32
2.6.2 Synthesis of batch water network
36
2.6.3 Synthesis of utility gas network
38
2.6.4 Synthesis of property-based network
39
2.7 Conclusions
40
x
3
METHODOLOGY DEVELOPMENT
42
3.1 Introduction
42
3.2 Cascade analysis technique
42
3.2.1 Interval resource balance table
43
3.2.2 Resource cascade diagram
44
3.3 Time-dependant cascade analysis technique for
47
batch processes
3.4 Major assumptions for cascade analysis
49
technique
4
3.5 Conclusion
50
RESULT AND DISCUSSION – WATER
51
CASCADE ANALYSIS
4.1 Introduction
51
4.2 Example 4.1 - Acrylonitrile production
52
4.3 WCA for AN case study
56
4.4 WCA mass transfer-based water-using
59
processes
4.4.1 Example 4.2 – Wang and Smith (1997)
60
4.4.2 Example 4.3 – Olesen and Polley (1997)
61
4.4.3 Example 4 – Polley and Polley (2000)
62
4.4.4 Example 5 – Wang and Smith (1995a)
63
4.5 Multiple pinch problem
65
4.6 Assessing options for process changes via the
67
WCA
4.7 Optimisation of regeneration unit to achieve
69
zero discharge
5
4.8 Conclusion
75
RESULT AND DISCUSSION – TIME-
76
DEPENDENT WATER CASCADE ANALYSIS
5.1 Introduction
76
5.2 Time-dependent water cascade analysis
76
5.3 Example 5.1 - Kim and Smith (2004)
77
5.3.1 Targeting for batch water network without
79
xi
water storage tank
5.3.2 Targeting for Batch water network with
80
water storage tank systems
6
5.4 Batch water network design
84
5.5 Example 5.2 - Wang and Smith (1995b)
88
5.6 Conclusion
90
RESULT AND DISCUSSION – GAS CASCADE
91
ANALYSIS
7
6.1 Introduction
91
6.2 Nitrogen integration (Example 6.1)
91
6.3 Gas cascade analysis technique
93
6.4 Oxygen integration (Example 6.2)
95
6.5 Network design
96
6.6 Hydrogen integration (Example 6.3)
99
6.7 Appropriate placement of hydrogen purifier
101
6.8 Multiple-pinch problems (Example 6.4)
104
6.9 Conclusion
108
RESULT AND DISCUSSION – PROPERTY
109
CASCADE ANALYSIS
8
7.1 Introduction
109
7.2 Metal degreasing process (Example 7.1)
109
7.3 The concept of material surplus
112
7.4 Property cascade analysis technique
116
7.5 Property-based network design
118
7.6 Process modifications
121
7.7 Papermaking process (Example 7.2)
122
7.8 Conclusion
125
CONCLUSIONS AND FUTURE WORKS
127
5.1 Summary and significance
127
5.2 Future works
129
REFERENCES
132
Appendices A – Water cascade tables for other case studies
146
Appendices B – refereed journal/magazine publications
162
xii
LIST OF TABLES
TABLE NO.
TITLE
PAGE
2.1
Operator expressions for common properties
29
3.1
Interval resource balance table
43
3.2
Resource cascade table
47
3.3
Time interval table for batch processes
47
3.4
Time-dependent cascade analysis for batch processes
48
4.1
Limiting water data for AN production (Example 4.1)
54
4.2
Interval resource balance table for AN case study
56
4.3
WCT for AN case study (Example 4.1)
58
4.4
Limiting water data for Example 4.2 (Wang and Smith, 1994)
60
4.5
WCT for Example 4.2
60
4.6
Limiting water data for Example 4.3 (Olesen and Polley, 1997)
61
4.7
WCT for Example 4.3
61
4.8
Limiting water data for Example 4.4 (Polley and Polley, 2000)
62
4.9
WCT for Example 4.4
62
4.10
Limiting water data for Example 4.5 (Wang and Smith, 1995a)
63
4.11
WCT for Example 4.5
64
4.12
Limiting water data for Example 4.6 (Sorin and Bédard, 1999)
65
4.13
WCT for Example 4.6
66
4.14
WCT for process involving partial regeneration of off-gas
67
condensate
4.15
WCT for stream regeneration and process changes
68
4.16
Limiting water data for Example 4.7
69
4.17
WCT for Example 4.7
70
4.18
Zero discharge solution with DAF units installed
73
xiii
5.1
Limiting water data for Example 5.1
78
5.2
Time interval table for Example 5.1
79
5.3
TDWCA for Example 5.1 (without water storage system)
80
5.4
Targeting overall fresh water and wastewater flows with
81
TDWCA for Example 5.1 (network with water storage system)
5.5
Identification of interval-based fresh water and wastewater
83
targets, and storage capacity target for Example 5.1 (network
with water storage system)
5.6
Limiting water data for Example 5.2 (Wang and Smith, 1995b)
88
5.7
TDWCA for Example 5.2 (network with water storage system)
89
6.1
Limiting data for Example 6.1 (nitrogen integration)
93
6.2
GCT for nitrogen integration (Example 6.1)
94
6.3
Limiting data for oxygen integration (Example 6.2)
96
6.4
GCT for Example 6.2
96
6.5
Limiting data for hydrogen integration (Example 6.3)
100
6.6
GCT for Example 6.3
101
6.7
GCT for Example 6.3 (regeneration with membrane)
103
6.8
GCT for Example 6.3 (regeneration with PSA)
104
6.9
Hydrogen source and sink data for Example 6.4 (multiple-
105
pinch problem)
6.10
GCT for Example 6.4
105
6.11
GCT for Example 6.4 (regeneration with membrane)
107
6.12
GCT for Example 6.4 (regeneration with PSA)
108
7.1
Data for Example 7.1 (Kazantzi and El-Halwagi, 2005)
111
7.2
Limiting data for Example 7.1
112
7.3
PCT for metal degreasing process (Example 7.1)
116
7.4
Limiting data for papermaking process (Example 7.2)
124
7.5
PCT for papermaking process (Example 7.2)
125
xiv
LIST OF FIGURES
FIGURE NO.
1.1
TITLE
PAGE
A flow diagram illustrating the conceptual links between the
7
chapters
2.1
Mass transfer-based water-using operations: (a) Vessel
10
washing; (b) Sour gas absorption where water sink and
water source exist with equal flowrates (Manan et al., 2004)
2.2
Non-mass transfer-based water-using operations: (a) a
10
reactor that consumes water in aniline production; (b) a
reactor that produces water as a byproduct in acrylonitrile
production (Manan et al., 2004)
2.3
Two other common types of the non-mass transfer-based
11
water-using operations: (a) cooling tower make up; (b)
boiler blow-down (Manan et al., 2004)
2.4
A reactor system that cannot be modelled purely as a mass
11
transfer-based operation (Hallale, 2002)
2.5
Construction of limiting water profile and water flowrate
13
targeting
2.6
Water surplus diagram by Hallale (2002)
13
2.7
The tedious iterative steps of constructing the water surplus
14
diagram
2.8
Material-recovery pinch diagram
15
2.9
Methods on reducing wastewater consumption – (a) reuse,
16
(b) regeneration-reuse, and (c) regeneration-recycling
(Wang and Smith, 1994)
2.10
Appropriate placement of water regeneration unit
17
xv
2.11
Time-pinch analysis technique by Wang and Smith (1995b)
18
2.12
Water utilisation networks by Wang and Smith (1995b)
18
2.13
Simplified flow diagram for a crude oil refinery. Hydrogen-
19
consuming processes are highlighted in bold (Towler et al.,
1996; Alves and Towler, 2002)
2.14
Simplified diagram of a hydrogen-consuming process
21
2.15
Construction of hydrogen surplus diagram (Alves and
23
Towler, 2002; Hallale et al. 2002)
2.16
Placement of hydrogen purifier in the context of overall
25
hydrogen network (Hallale et al., 2002)
2.17
Property-based pinch diagram (Kazantzi and El-Halwagi,
30
2005)
2.18
Property-based pinch diagram when fresh feed is having the
31
highest operator value among all process sources (Kazantzi
and El-Halwagi, 2005)
2.19
Reduction of fresh feed and discharge flowrates in a
32
property-based network (Kazantzi and El-Halwagi, 2005)
3.1
The principle of resource cascading (y1 < y2)
44
3.2
Resource cascade diagram: (a) flowrate cascade; (b) load
45
cascade; (c) determination of interval fresh feed flowrate
4.1
Flowsheet for AN production (El-Halwagi, 1997)
52
4.2
Targeting model by El-Halwagi (1997)
55
4.3
Infeasible water cascade diagram with zero fresh water
57
flowrate
4.4
A feasible water cascade diagram for AN case study
58
4.5
Final solution to the AN case study with water reuse and
68
process changes (El-Halwagi, 1997)
4.6
Placement of a regeneration unit in the context of an overall
72
network
4.7
Reduction of fresh water and wastewater flowrates as a
74
function of regeneration flowrate
4.8
Zero wastewater discharge network for the paper mill case
study
74
xvi
5.1
Network design for each time interval in Example 5.1: (a) 0-
86
1.0 hr; (b) 1.0-3.0 hr; (c) 3.0-3.5 hr; (d) 3.5-5.0 hr
5.2
Batch water network for Example 5.1 (without water storage
87
system) represented in time-water network
5.3
Batch water network for Example 5.1 (network with water
88
storage system)
5.4
Batch network design for Example 5.2
89
6.1
Process flow diagram of a magnetic tape manufacturing
92
process (El-Halwagi, 1997)
6.2
Process flow diagram for oxygen integration (Example 6.2)
95
6.3
Process flow diagram of a magnetic tape manufacturing
98
process (Example 6.1) with exhaust gas reuse and recycling
6.4
Oxygen integration network for Example 6.2
99
6.5
One possible network design for Example 6.4: flowrate in
106
mol/s while impurity concentration in mol%
7.1
Metal degreasing process (Kazantzi and El-Halwagi, 2005)
110
7.2
Sink and source composite plots for Example 7.1, with the
113
solvent flowrate set to 0 kg/s
7.3
Construction of a property surplus diagram: (a) Sink and
115
source composite plots; (b) Property surplus diagram
7.4
A feasible property surplus diagram for Example 7.1
117
7.5
Balanced material sink and source composite diagram for
118
Example 7.1
7.6
Network design for Example 7.1
120
7.7
Network design for degreaser plant to achieve MRR
120
objective (before process modification)
7.8
Network design for metal degreasing process after process
122
modification
7.9
A papermaking process (Kazantzi and El-Halwagi, 2005)
123
7.10
Final configuration of the papermaking process
125
xvii
LIST OF SYMBOLS
Symbols in Roman
C
-
impurity concentration
Ci
-
impurity concentration of process sinks j
Cin
-
inlet concentration of regeneration unit
Cj
-
impurity concentration of process source i
Ck
-
impurity concentration at level k
CM
-
impurity concentration of make-up stream
CP
-
impurity concentration of purge stream
CR
-
impurity concentration of recycle stream
Cout
-
outlet concentration of regeneration unit
Cum. Δm
-
cumulative load
ΔCRG
-
inlet and outlet concentration of regeneration unit
Δm
-
mass/property load
Δmjin
-
inlet mass/property load of process sinks j
Δmjmin
-
minimum mass/property load of process sinks j
Δmjmax
-
maximum mass/property load of process sinks j
ΔmS,i
-
mass load removed from a water source i
Δy
-
driving force difference
Δt
-
duration of time interval
FC
-
cumulative flowrate
FD
-
discharge flowrate
FF
-
fresh feed flowrate
FF, k
-
interval fresh feed flowrate
Fi
-
flowrate of process sinks j
Fj
-
flowrate of process source i
xviii
FM
-
flowrate of make-up stream
FP
-
flowrate of purge stream
FR
-
flowrate of recycle stream
FRG, i
-
flowrate sent for regeneration from water source i
Freg
-
total regeneration flowrate
l
-
time interval
M
-
material content
MFW
-
flow of fresh water (batch process)
MFW, k
-
interval fresh water flowrate (batch process)
Mi
-
flow of process sinks j (batch process)
Mj
-
flow of process source i (batch process)
Mi, j
-
flow fed from source i to sink j (batch process)
MST
-
water storage capacity
MWW
-
flow of wastewater (batch process)
NSK
-
number of process sink
NSR
-
number of process source
n
-
number of driving force levels
p
-
property
p
-
mean property
pjin
-
inlet property of sink j
pjmin
-
minimum property of sink j
pjmax
-
maximum property of sink j
q
-
number of time intervals
RVP
-
Reid vapour pressure
R
-
resistivity
R∞
-
reflectivity
RP
-
removal percentage
SK
-
process sink
SR
-
process source
Σi Fi
-
summation of process source flowrate
Σj Fj
-
summation of process sink flowrate
Σi Mi
-
summation of process source flow (batch process)
Σj Mj
-
summation of process sink flow (batch process)
xix
t
-
time
ts
-
start time
tt
-
end time
xi
-
fractional contribution of source i
y
-
driving force
yk
-
driving force at level k
Δ
-
difference
Σ
-
summation
μ
-
viscosity
ρ
-
density
ψ
-
property operator
ψi
-
property operator of source i
ψj
-
property operator of sink j
ψ jin
-
inlet property operator of sink j
ψ jmin
-
minimum property operator of sink j
ψ jmax
-
maximum property operator of sink j
in
-
inlet
min
-
minimum
max
-
maximum
s
-
start
t
-
end
out
-
outlet
Greek letter
Superscript
xx
Subscripts
C
-
cumulative
F
-
fresh feed
D
-
waste discharge
i
-
process source
in
-
inlet
j
-
process sink
k
-
number of driving force level
M
-
make-up
out
-
outlet
P
-
purge
R
-
recycle
RG
-
regeneration
reg
-
regeneration
SK
-
sink
SR
-
source