Pinch Analysis and Process Integration, Second Edition: A User Guide on Process Integration for the Efficient Use of Energy

415 Pages·2007·5.39 MB·English

by  Ian C. Kemp

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Pinch Analysis and Process Integration
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To Dad and Sue
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Pinch Analysis and Process Integration
A User Guide on Process Integration for
the Efficient Use of Energy
Second edition
Ian C Kemp
The authors of the First Edition were: B. Linnhoff, D.W. Townsend, D. Boland, G.F. Hewitt,
B.E.A. Thomas, A.R. Guy and R.H. Marsland
The IChemE Working Party was chaired by B.E.A. Thomas.
AMSTERDAM •BOSTON •HEIDELBERG •LONDON •NEW YORK •OXFORD
PARIS •SAN DIEGO •SAN FRANCISCO •SINGAPORE •SYDNEY •TOKYO
Butterworth-Heinemann is an imprint of Elsevier
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Butterworth-Heinemann is an imprint of Elsevier
Linacre House, Jordan Hill, Oxford OX2 8DP, UK
30 Corporate Drive, Suite 400, Burlington, MA 01803, USA
First edition 1982
Revised First edition 1994
Second edition 2007
Copyright © 2007, Elsevier Ltd. All rights reserved
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ISBN 13: 978 0 75068 260 2
ISBN 10: 0 7506 8260 4
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Contents
Foreword xii
Foreword to the first edition xiii
Preface xiv
Acknowledgements xvi
Figure acknowledgements xvii
1 Introduction 1
1.1 What is pinch analysis? 1
1.2 History and industrial experience 2
1.3 Why does pinch analysis work? 4
1.4 The concept of process synthesis 5
1.5 The role of thermodynamics in process design 9
1.5.1 How can we apply thermodynamics practically? 9
1.5.2 Capital and energy costs 9
1.6 Learning and applying the techniques 11
2 Key concepts of pinch analysis 15
2.1 Heat recovery and heat exchange 15
2.1.1 Basic concepts of heat exchange 15
2.1.2 The temperature–enthalpy diagram 16
2.1.3 Composite curves 19
2.1.4 A targeting procedure: the “Problem Table” 21
2.1.5 The grand composite curve and shifted composite curves 25
2.2 The pinch and its significance 27
2.3 Heat exchanger network design 29
2.3.1 Network grid representation 29
2.3.2 A “commonsense” network design 30
2.3.3 Design for maximum energy recovery 31
2.3.4 A word about design strategy 35
2.4 Choosing (cid:2)T : supertargeting 36
min
2.4.1 Further implications of the choice of (cid:2)T 36
min
2.5 Methodology of pinch analysis 38
2.5.1 The range of pinch analysis techniques 38
2.5.2 How to do a pinch study 38
Exercise 39
3 Data extraction and energy targeting 41
3.1 Data extraction 41
3.1.1 Heat and mass balance 41
3.1.2 Stream data extraction 42
3.1.3 Calculating heat loads and heat capacities 43
3.1.4 Choosing streams 45
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3.1.5 Mixing 47
3.1.6 Heat losses 47
3.1.7 Summary guidelines 49
3.2 Case study: organics distillation plant 49
3.2.1 Process description 49
3.2.2 Heat and mass balance 49
3.2.3 Stream data extraction 52
3.2.4 Cost data 52
3.3 Energy targeting 53
3.3.1 (cid:2)T contributions for individual streams 53
min
3.3.2 Threshold problems 54
3.4 Multiple utilities 56
3.4.1 Types of utility 56
3.4.2 The Appropriate Placement principle 57
3.4.3 Constant-temperature utilities 58
3.4.4 Utility pinches 59
3.4.5 Variable-temperature utilities 60
3.4.6 Balanced composite and grand composite curves 62
3.4.7 Choice of multiple utility levels 67
3.5 More advanced energy targeting 67
3.5.1 Zonal targeting 67
3.5.2 Pressure drop targeting 68
3.6 Targeting heat exchange units, area and shells 69
3.6.1 Targeting for number of units 69
3.6.2 Targeting for the minimum number of units 72
3.6.3 Area targeting 73
3.6.4 Deviations from pure countercurrent flow 76
3.6.5 Number of shells targeting 76
3.6.6 Performance of existing systems 76
3.6.7 Topology traps 77
3.7 Supertargeting: cost targeting for optimal (cid:2)T 79
min
3.7.1 Trade-offs in choosing (cid:2)T 79
min
3.7.2 Illustration for two-stream example 80
3.7.3 Factors affecting the optimal (cid:2)T 82
min
3.7.4 Approximate estimation of ideal (cid:2)T 83
min
3.8 Targeting for organics distillation plant case study 85
3.8.1 Energy targeting 85
3.8.2 Area targeting 85
3.8.3 Cost targeting 87
3.8.4 Zonal targeting 90
3.8.5 Targeting with utility streams included 92
3.9 Appendix: Algorithms for Problem Table and composite curves 95
3.9.1 Problem Table and GCC 95
3.9.2 Composite curves 96
Exercises 97
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4 Heat exchanger network design 99
4.1 Introduction 99
4.2 Heat exchange equipment 99
4.2.1 Types of heat exchanger 99
4.2.2 Shell-and-tube exchangers 100
4.2.3 Plate exchangers 103
4.2.4 Recuperative exchangers 106
4.2.5 Heat recovery to and from solids 106
4.2.6 Multi-stream heat exchangers 107
4.3 Stream splitting and cyclic matching 108
4.3.1 Stream splitting 108
4.3.2 Cyclic matching 114
4.3.3 Design away from the pinch 114
4.4 Network relaxation 117
4.4.1 Using loops and paths 117
4.4.2 Network and exchanger temperature differences 123
4.4.3 Alternative network design and relaxation strategy 123
4.5 More complex designs 125
4.5.1 Threshold problems 125
4.5.2 Constraints 127
4.6 Multiple pinches and near-pinches 130
4.6.1 Definition 130
4.6.2 Network design with multiple pinches 131
4.7 Retrofit design 132
4.7.1 Alternative strategies for process revamp 132
4.7.2 Network optimisation 135
4.7.3 The network pinch 135
4.7.4 Example retrofit network design 137
4.7.5 Automated network design 143
4.8 Operability: multiple base case design 145
4.9 Network design for organics distillation case study 148
4.9.1 Units separate 148
4.9.2 Units integrated 152
4.9.3 Including utility streams 154
4.9.4 Multiple utilities 154
4.10 Conclusions 157
Exercises 157
5 Utilities, heat and power systems 161
5.1 Concepts 161
5.1.1 Introduction 161
5.1.2 Types of heat and power systems 161
5.1.3 Basic principles of heat engines and heat pumps 162
5.1.4 Appropriate placement for heat engines and heat pumps 164
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5.2 CHP systems 167
5.2.1 Practical heat engines 167
5.2.2 Selection of a CHP system 168
5.2.3 Refinements to site heat and power systems 172
5.2.4 Economic evaluation 177
5.2.5 Organic Rankine cycles 182
5.3 Heat pumps and refrigeration systems 184
5.3.1 Heat pump cycles 184
5.3.2 Refrigeration systems 188
5.3.3 Shaft work analysis 191
5.3.4 Cooling water systems 192
5.3.5 Summary 193
5.4 Total site analysis 194
5.4.1 Energy targeting for the overall site 195
5.4.2 Total site profiles 196
5.4.3 Practical heat recovery through the site steam system 197
5.4.4 Indirect heat transfer 198
5.4.5 Estimation of cogeneration targets 200
5.4.6 Emissions targeting 201
5.5 Worked example: organics distillation unit 202
5.6 Case studies and examples 205
5.6.1 Whisky distillery 205
5.6.2 CHP with geothermal district heating 208
5.6.3 Tropical power generation and desalination 209
5.6.4 Hospital site 210
Exercises 210
6 Process change and evolution 213
6.1 Concepts 213
6.2 General principles 215
6.2.1 The basic objective 215
6.2.2 The plus–minus principle 216
6.2.3 Appropriate Placement applied to unit operations 218
6.3 Reactor systems 220
6.4 Distillation columns 222
6.4.1 Overview of basic analysis method 222
6.4.2 Refinements to the analysis 223
6.4.3 Multiple columns 224
6.4.4 Distillation column profiles 225
6.4.5 Distillation column sequencing 229
6.5 Other separation systems 233
6.5.1 Evaporator systems 233
6.5.2 Flash systems 241
6.5.3 Solids drying 244
6.5.4 Other separation methods 247
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6.6 Application to the organics distillation process case study 247
6.6.1 Identifying potential process changes 247
6.6.2 Eliminating bottoms rundown: detailed analysis 249
6.6.3 Economic assessment 253
6.7 Summary and conclusions 255
Exercises 255
7 Batch and time-dependent processes 257
7.1 Introduction 257
7.2 Concepts 259
7.3 Types of streams in batch processes 263
7.4 Time intervals 265
7.5 Calculating energy targets 265
7.5.1 Formation of stream data 266
7.5.2 Time average model 266
7.5.3 Time slice model 266
7.5.4 Heat storage possibilities 269
7.6 Heat exchanger network design 273
7.6.1 Networks based on continuous or averaged
process 273
7.6.2 Networks based on individual time intervals 274
7.7 Rescheduling 277
7.7.1 Definition 277
7.7.2 Classification of rescheduling types 277
7.7.3 Methodology 279
7.8 Debottlenecking 281
7.9 Other time-dependent applications 285
7.9.1 Start-up and shutdown 285
7.9.2 Day/night variations 286
7.10 Conclusions 286
8 Applying the technology in practice 289
8.1 Introduction 289
8.2 How to do a pinch study 289
8.3 Heat and mass balance 290
8.4 Stream data extraction 291
8.4.1 Mixing and splitting junctions 292
8.4.2 Effective process temperatures 294
8.4.3 Process steam and water 295
8.4.4 Soft data 296
8.4.5 Units 297
8.4.6 Worked example 298
8.5 Targeting and network design 301
8.5.1 Targeting 301
8.5.2 Network design 301