Pinch Analysis and Process Integration

Description

Pinch analysis and related techniques are the key to design of inherently energy-efficient plants. This book shows engineers how to understand and optimize energy use in their processes, whether large or small. Energy savings go straight to the bottom line as increased profit, as well as reducing emissions.

This is the key guide to process integration for both experienced and newly qualified engineers, as well as academics and students. It begins with an introduction to the main concepts of pinch analysis, the calculation of energy targets for a given process, the pinch temperature and the golden rules of pinch-based design to meet energy targets.

The book shows how to extract the stream data necessary for a pinch analysis and describes the targeting process in depth. Other essential details include the design of heat exchanger networks, hot and cold utility systems, CHP (combined heat and power), refrigeration and optimization of system operating conditions. Many tips and techniques for practical application are covered, supported by several detailed case studies and other examples covering a wide range of industries, including buildings and other non-process situations.

The only dedicated pinch analysis and process integration guide, fully revised and expanded supported by free downloadable energy targeting software
The perfect guide and reference for chemical process, food and biochemical engineers, plant engineers and professionals concerned with energy optimisation, including building designers
Covers the practical analysis of both new and existing systems, with ful details of industrial applications and case studies

Front Cover 2
Pinch Analysis and Process Integration 5
Copyright page 6
Contents 7
Foreword 14
Foreword to the first edition 15
Preface 16
Acknowledgements 18
Figure acknowledgements 19
Chapter 1: Introduction 21
- 1.1 What is pinch analysis? 21
- 1.2 History and industrial experience 22
- 1.3 Why does pinch analysis work? 24
- 1.4 The concept of process synthesis 25

Front Cover 2
Pinch Analysis and Process Integration 5
Copyright page 6
Contents 7
Foreword 14
Foreword to the first edition 15
Preface 16
Acknowledgements 18
Figure acknowledgements 19
Chapter 1: Introduction 21
- 1.1 What is pinch analysis? 21
- 1.2 History and industrial experience 22
- 1.3 Why does pinch analysis work? 24
- 1.4 The concept of process synthesis 25
- 1.5 The role of thermodynamics in process design 29
  - 1.5.1 How can we apply thermodynamics practically? 29
  - 1.5.2 Capital and energy costs 29
- 1.6 Learning and applying the techniques 31
Chapter 2: Key concepts of pinch analysis 35
- 2.1 Heat recovery and heat exchange 35
  - 2.1.1 Basic concepts of heat exchange 35
  - 2.1.2 The temperature–enthalpy diagram 36
  - 2.1.3 Composite curves 39
  - 2.1.4 A targeting procedure: the "Problem Table" 41
  - 2.1.5 The grand composite curve and shifted composite curves 45
- 2.2 The pinch and its significance 47
- 2.3 Heat exchanger network design 49
  - 2.3.1 Network grid representation 49
  - 2.3.2 A "commonsense" network design 50
  - 2.3.3 Design for maximum energy recovery 51
  - 2.3.4 A word about design strategy 55
- 2.4 Choosing ΔT[sub(min)]: supertargeting 56
  - 2.4.1 Further implications of the choice of ΔT[sub(min)] 56
- 2.5 Methodology of pinch analysis 58
  - 2.5.2 How to do a pinch study 58
  - 2.5.1 The range of pinch analysis techniques 58
- Exercise 59
Chapter 3: Data extraction and energy targeting 61
- 3.1 Data extraction 61
  - 3.1.1 Heat and mass balance 61
  - 3.1.2 Stream data extraction 62
  - 3.1.3 Calculating heat loads and heat capacities 63
  - 3.1.4 Choosing streams 65
  - 3.1.5 Mixing 67
  - 3.1.6 Heat losses 67
  - 3.1.7 Summary guidelines 69
- 3.2 Case study: organics distillation plant 69
  - 3.2.1 Process description 69
  - 3.2.2 Heat and mass balance 69
  - 3.2.3 Stream data extraction 72
  - 3.2.4 Cost data 72
- 3.3 Energy targeting 73
  - 3.3.1 ΔT[sub(min)] contributions for individual streams 73
  - 3.3.2 Threshold problems 74
- 3.4 Multiple utilities 76
  - 3.4.1 Types of utility 76
  - 3.4.2 The Appropriate Placement principle 77
  - 3.4.3 Constant-temperature utilities 78
  - 3.4.4 Utility pinches 79
  - 3.4.5 Variable-temperature utilities 80
  - 3.4.6 Balanced composite and grand composite curves 82
  - 3.4.7 Choice of multiple utility levels 87
- 3.5 More advanced energy targeting 87
  - 3.5.1 Zonal targeting 87
  - 3.5.2 Pressure drop targeting 88
- 3.6 Targeting heat exchange units, area and shells 89
  - 3.6.1 Targeting for number of units 89
  - 3.6.2 Targeting for the minimum number of units 92
  - 3.6.3 Area targeting 93
  - 3.6.5 Number of shells targeting 96
  - 3.6.6 Performance of existing systems 96
  - 3.6.4 Deviations from pure countercurrent flow 96
  - 3.6.7 Topology traps 97
- 3.7 Supertargeting: cost targeting for optimal ΔT[sub(min)] 99
  - 3.7.1 Trade-offs in choosing ΔT[sub(min)] 99
  - 3.7.2 Illustration for two-stream example 100
  - 3.7.3 Factors affecting the optimal ΔT[sub(min)] 102
  - 3.7.4 Approximate estimation of ideal ΔT[sub(min)] 103
- 3.8 Targeting for organics distillation plant case study 105
  - 3.8.1 Energy targeting 105
  - 3.8.2 Area targeting 105
  - 3.8.3 Cost targeting 107
  - 3.8.4 Zonal targeting 110
  - 3.8.5 Targeting with utility streams included 112
- 3.9 Appendix: Algorithms for Problem Table and composite curves 115
  - 3.9.1 Problem Table and GCC 115
  - 3.9.2 Composite curves 116
- Exercises 117
Chapter 4: Heat exchanger network design 119
- 4.1 Introduction 119
- 4.2 Heat exchange equipment 119
  - 4.2.1 Types of heat exchanger 119
  - 4.2.2 Shell-and-tube exchangers 120
  - 4.2.3 Plate exchangers 123
  - 4.2.4 Recuperative exchangers 126
  - 4.2.5 Heat recovery to and from solids 126
  - 4.2.6 Multi-stream heat exchangers 127
- 4.3 Stream splitting and cyclic matching 128
  - 4.3.1 Stream splitting 128
  - 4.3.2 Cyclic matching 134
  - 4.3.3 Design away from the pinch 134
- 4.4 Network relaxation 137
  - 4.4.1 Using loops and paths 137
  - 4.4.2 Network and exchanger temperature differences 143
  - 4.4.3 Alternative network design and relaxation strategy 143
- 4.5 More complex designs 145
  - 4.5.1 Threshold problems 145
  - 4.5.2 Constraints 147
- 4.6 Multiple pinches and near-pinches 150
  - 4.6.1 Definition 150
  - 4.6.2 Network design with multiple pinches 151
- 4.7 Retrofit design 152
  - 4.7.1 Alternative strategies for process revamp 152
  - 4.7.2 Network optimisation 155
  - 4.7.3 The network pinch 155
  - 4.7.4 Example retrofit network design 157
  - 4.7.5 Automated network design 163
- 4.8 Operability: multiple base case design 165
- 4.9 Network design for organics distillation case study 168
  - 4.9.1 Units separate 168
  - 4.9.2 Units integrated 172
  - 4.9.3 Including utility streams 174
  - 4.9.4 Multiple utilities 174
- 4.10 Conclusions 177
- Exercises 177
Chapter 5: Utilities, heat and power systems 181
- 5.1 Concepts 181
  - 5.1.1 Introduction 181
  - 5.1.2 Types of heat and power systems 181
  - 5.1.3 Basic principles of heat engines and heat pumps 182
  - 5.1.4 Appropriate placement for heat engines and heat pumps 184
- 5.2 CHP systems 187
  - 5.2.1 Practical heat engines 187
  - 5.2.2 Selection of a CHP system 188
  - 5.2.3 Refinements to site heat and power systems 192
  - 5.2.4 Economic evaluation 197
  - 5.2.5 Organic Rankine cycles 202
- 5.3 Heat pumps and refrigeration systems 204
  - 5.3.1 Heat pump cycles 204
  - 5.3.2 Refrigeration systems 208
  - 5.3.3 Shaft work analysis 211
  - 5.3.4 Cooling water systems 212
  - 5.3.5 Summary 213
- 5.4 Total site analysis 214
  - 5.4.1 Energy targeting for the overall site 215
  - 5.4.2 Total site profiles 216
  - 5.4.3 Practical heat recovery through the site steam system 217
  - 5.4.4 Indirect heat transfer 218
  - 5.4.5 Estimation of cogeneration targets 220
  - 5.4.6 Emissions targeting 221
- 5.5 Worked example: organics distillation unit 222
- 5.6 Case studies and examples 225
  - 5.6.1 Whisky distillery 225
  - 5.6.2 CHP with geothermal district heating 228
  - 5.6.3 Tropical power generation and desalination 229
  - 5.6.4 Hospital site 230
- Exercises 230
Chapter 6: Process change and evolution 233
- 6.1 Concepts 233
- 6.2 General principles 235
  - 6.2.1 The basic objective 235
  - 6.2.2 The plus–minus principle 236
  - 6.2.3 Appropriate Placement applied to unit operations 238
- 6.3 Reactor systems 240
- 6.4 Distillation columns 242
  - 6.4.1 Overview of basic analysis method 242
  - 6.4.2 Refinements to the analysis 243
  - 6.4.3 Multiple columns 244
  - 6.4.4 Distillation column profiles 245
  - 6.4.5 Distillation column sequencing 249
- 6.5 Other separation systems 253
  - 6.5.1 Evaporator systems 253
  - 6.5.2 Flash systems 261
  - 6.5.3 Solids drying 264
  - 6.5.4 Other separation methods 267
- 6.6 Application to the organics distillation process case study 267
  - 6.6.1 Identifying potential process changes 267
  - 6.6.2 Eliminating bottoms rundown: detailed analysis 269
  - 6.6.3 Economic assessment 273
- 6.7 Summary and conclusions 275
- Exercises 275
Chapter 7: Batch and time-dependent processes 277
- 7.1 Introduction 277
- 7.2 Concepts 279
- 7.3 Types of streams in batch processes 283
- 7.4 Time intervals 285
- 7.5 Calculating energy targets 285
  - 7.5.1 Formation of stream data 286
  - 7.5.2 Time average model 286
  - 7.5.3 Time slice model 286
  - 7.5.4 Heat storage possibilities 289
- 7.6 Heat exchanger network design 293
  - 7.6.1 Networks based on continuous or averaged process 293
  - 7.6.2 Networks based on individual time intervals 294
- 7.7 Rescheduling 297
  - 7.7.1 Definition 297
  - 7.7.2 Classification of rescheduling types 297
  - 7.7.3 Methodology 299
- 7.8 Debottlenecking 301
- 7.9 Other time-dependent applications 305
  - 7.9.1 Start-up and shutdown 305
  - 7.9.2 Day/night variations 306
- 7.10 Conclusions 306
Chapter 8: Applying the technology in practice 309
- 8.1 Introduction 309
- 8.2 How to do a pinch study 309
- 8.3 Heat and mass balance 310
- 8.4 Stream data extraction 311
  - 8.4.1 Mixing and splitting junctions 312
  - 8.4.2 Effective process temperatures 314
  - 8.4.3 Process steam and water 315
  - 8.4.4 Soft data 316
  - 8.4.5 Units 317
  - 8.4.6 Worked example 318
- 8.5 Targeting and network design 321
  - 8.5.1 Targeting 321
  - 8.5.2 Network design 321
- 8.6 Targeting software 322
  - 8.6.1 Options available 322
  - 8.6.2 Spreadsheet accompanying this book 323
- 8.7 Industrial experience 323
  - 8.7.1 Oil refining 326
  - 8.7.2 Bulk chemicals – continuous 327
  - 8.7.3 Speciality and batch chemicals and pharmaceuticals 327
  - 8.7.5 Food and beverage 328
  - 8.7.4 Pulp and paper 328
  - 8.7.7 Minerals and metals 329
  - 8.7.6 Consumer products and textiles 329
  - 8.7.8 Heat and power utilities 330
  - 8.7.9 Buildings 331
- Exercises 331
Chapter 9: Case studies 333
- 9.2 Crude preheat train 333
  - 9.2.2 Data extraction and energy targeting 334
  - 9.2.1 Process description 334
  - 9.2.3 Pinch identification and network design 339
  - 9.2.4 Design evolution 345
  - 9.2.5 Design evaluation 349
  - 9.2.6 Conclusions 350
- 9.1 Introduction 333
- 9.3 Aromatics plant 350
  - 9.3.1 Introduction 350
  - 9.3.3 Stream data extraction 352
  - 9.3.2 Process description 352
  - 9.3.4 Energy targeting 356
  - 9.3.5 Design of an MER network 358
  - 9.3.6 Network design based on existing layout 364
  - 9.3.7 Practical process design considerations 366
  - 9.3.8 Further considerations 367
  - 9.3.9 Targeting and design with alternative stream data 369
  - 9.3.10 Conclusions 371
- 9.4 Evaporator/dryer plant 371
  - 9.4.1 Process description 372
  - 9.4.2 Stream data extraction 372
  - 9.4.3 Energy targeting 376
  - 9.4.4 Heat pumping strategy 376
  - 9.4.5 Process change analysis 378
  - 9.4.6 Selection of final scheme layout 381
  - 9.4.7 Conclusions 385
- 9.5 Organic chemicals manufacturing site 386
  - 9.5.1 Process description and targeting 386
  - 9.5.2 Practical implementation 387
  - 9.5.3 Conclusions 389
- 9.6 Hospital site 389
  - 9.6.1 Site description and stream data extraction 389
  - 9.6.2 Targeting using time intervals 391
  - 9.6.3 Rescheduling possibilities 392
  - 9.6.4 Process change possibilities 394
  - 9.6.5 Opportunities for combined heat and power 395
  - 9.6.6 Conclusions 396
- 9.7 Conclusions 397
- Exercises 398
Chapter 10: Conclusions 399
Notation 401
Glossary of terms 403
- A 403
- D 403
- G 403
- B 403
- E 403
- C 403
- F 403
- I 404
- N 404
- L 404
- H 404
- M 404
- T 405
- R 405
- O 405
- S 405
- P 405
- U 406
Further reading 407
Appendix – using the spreadsheet software 409
Index 411
- B 411
- C 411
- A 411
- D 412
- G 412
- E 412
- F 412
- M 413
- J 413

Author's affiliation

Ian C. Kemp: Previously of Aspen Technology

A User Guide on Process Integration for the Efficient Use of Energy

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