Thermal Safety of Chemical Processes: Risk Assessment and Process Design
by Francis Stoessel
by Francis Stoessel
Contents
Preface xxi
Acknowledgments xxv
Part I General Aspects of Thermal Process Safety 1
1 Introduction to Risk Analysis of Fine Chemical Processes 3
1.1 Chemical Industry and Safety 4
1.1.1 Chemical Industry and Society 4
1.1.1.1 Product Safety 4
1.1.1.2 Process Safety 5
1.1.1.3 Accidents and Risk Perception in Chemical Industry 5
1.1.2 Responsibility 6
1.1.3 Definitions and Concepts 7
1.1.3.1 Hazard 7
1.1.3.2 Risk 7
1.1.3.3 Safety 8
1.1.3.4 Security 8
1.1.3.5 Accepted Risk 8
1.2 Steps of Risk Analysis 8
1.2.1 Scope of Analysis 9
1.2.2 Safety Data Collection 10
1.2.3 Safe Conditions and Critical Limits 10
1.2.4 Identification of Deviations 10
1.2.5 Risk Assessment 11
1.2.6 Risk Matrixes 14
1.2.7 Risk-Reducing Measures 15
1.2.8 Residual Risk 17
1.3 Safety Data 17
1.3.1 Physical Properties 18
1.3.2 Chemical Properties 18
1.3.3 Toxicity 18
1.3.4 Ecotoxicity 20
1.3.5 Fire and Explosion Data 20
1.3.6 Interactions 21
1.4 Systematic Identification of Hazards 21
1.4.1 Checklist Method 22
1.4.2 Failure Mode and Effect Analysis 24
1.4.3 Hazard and Operability Study 24
1.4.4 Decision Table 26
1.4.5 Event Tree Analysis 26
1.4.6 Fault Tree Analysis 27
1.4.7 Brainstorming 29
1.5 The Practice of Risk Analysis 29
1.5.1 Preparing the Risk Analysis 29
1.5.2 The Risk Analysis Team 30
1.5.3 The Team Leader 30
1.5.4 Finalizing the Risk Analysis 31
1.6 Exercises 31
References 32
2 Fundamentals of Thermal Process Safety 35
2.1 Energy Potential 37
2.1.1 Thermal Energy 37
2.1.1.1 Heat of Reaction 37
2.1.1.2 Heat of Decomposition 38
2.1.1.3 Heat Capacity 39
2.1.1.4 Adiabatic Temperature Rise 40
2.1.2 Pressure Effects 41
2.2 Effect of Temperature on Reaction Rate 41
2.2.1 Single Reaction 41
2.2.2 Multiple Reactions 42
2.3 Heat Balance 43
2.3.1 Terms of the Heat Balance 43
2.3.1.1 Heat Production 43
2.3.1.2 Heat Removal 44
2.3.1.3 Heat Accumulation 46
2.3.1.4 Convective Heat Exchange Due to Mass Flow 46
2.3.1.5 Sensible Heat Due to Feed 47
2.3.1.6 Stirrer 47
2.3.1.7 Heat Losses 47
2.3.2 Simplified Expression of the Heat Balance 48
2.3.3 Reaction Rate Under Adiabatic Conditions 49
2.4 Runaway Reactions 50
2.4.1 Thermal Explosions 50
2.4.2 Semenov Diagram 51
2.4.3 Parametric Sensitivity 52
2.4.4 Critical Temperature 53
2.4.5 Sensitivity Toward Variation of the Coolant Temperature 55
2.4.6 Time Frame of aThermal Explosion, the tmrad Concept 56
2.5 Exercises 57
References 59
3 Assessment of Thermal Risks 61
3.1 Thermal Process Safety 62
3.1.1 Thermal Risks 62
3.1.2 Processes Concerned byThermal Risks 62
3.2 Thermal Risk Assessment Criteria 63
3.2.1 Cooling Failure Scenario 63
3.2.2 Severity 66
3.2.3 Probability 68
3.2.4 Runaway Risk Assessment 70
3.3 Criticality of Chemical Processes 70
3.3.1 Assessment of the Criticality 70
3.3.2 Criticality Classes 72
3.3.2.1 Criticality Class 1 72
3.3.2.2 Criticality Class 2 72
3.3.2.3 Criticality Class 3 73
3.3.2.4 Criticality Class 4 73
3.3.2.5 Criticality Class 5 73
3.3.3 Special Cases of Criticality Assessment 76
3.3.4 Remarks on Criticality Class 5 76
3.3.5 Using MTT as a Safety Barrier 77
3.4 Assessment Procedures 81
3.4.1 General Rules for Thermal Safety Assessment 81
3.4.2 Practical Procedure for the Assessment ofThermal Risks 81
3.5 Exercises 85
References 87
4 Experimental Techniques 89
4.1 CalorimetricMeasurement Principles 90
4.1.1 Classification of Calorimeters 90
4.1.2 Temperature Control Modes of Calorimeters 90
4.1.2.1 Isothermal Mode 91
4.1.2.2 Dynamic Mode 91
4.1.2.3 Adiabatic 91
4.1.2.4 Isoperibolic 92
4.1.3 Heat Balance in Calorimeters 92
4.1.3.1 Ideal Accumulation 93
4.1.3.2 Ideal Heat Flow 93
4.1.3.3 Isoperibolic Methods 94
4.2 Instruments Used in Safety Laboratories 94
4.2.1 Characteristics of Instruments Used for Safety Studies 94
4.2.1.1 Sample Mass 94
4.2.1.2 Sensitivity 96
4.2.1.3 Construction of the Calorimeter 96
4.2.1.4 Calorimetric Cells for Safety Studies 96
4.2.2 Example of Instruments Used for Safety Studies 97
4.3 Microcalorimeters 97
4.3.1 Differential Scanning Calorimetry (DSC) 97
4.3.1.1 Principles of DSC 98
4.3.1.2 DSC and Safety Studies 98
4.3.1.3 DSC Crucibles 99
4.3.1.4 Applications 100
4.3.1.5 Sample Preparation 102
4.3.1.6 The Baseline Problem 103
4.3.2 Calvet Calorimeters 104
4.3.2.1 Principle 104
4.3.2.2 Applications 105
4.3.3 Thermal ActivityMonitor 106
4.3.3.1 Principle 106
4.3.3.2 Applications 107
4.4 Reaction Calorimeters 107
4.4.1 Purpose of Reaction Calorimeters 107
4.4.2 Principles of Reaction Calorimeters 108
4.4.2.1 Heat Flow Calorimeters 108
4.4.2.2 Heat Balance Calorimeters 109
4.4.2.3 Compensation Calorimeters 109
4.4.2.4 The Baseline Problem 109
4.4.3 Examples of Reaction Calorimeters 110
4.4.3.1 RC1 by Mettler Toledo 110
4.4.3.2 CPA 202 by ChemiSens 111
4.4.3.3 Calo 2310 by Systag 111
4.4.3.4 Small-Scale Reaction Calorimeters 111
4.4.3.5 Reaction Calorimetry at Industrial Scale 111
4.4.3.6 Reaction Calorimetry at Microscale 111
4.4.4 Applications 113
4.4.4.1 Thermal Data of Reactions 113
4.4.4.2 Reaction Kinetics 114
4.5 Adiabatic Calorimeters 114
4.5.1 Principle of Adiabatic Calorimetry 114
4.5.2 On the Thermal Inertia 115
4.5.3 Dewar Calorimeters 116
4.5.3.1 Measurement Principle 116
4.5.3.2 Applications 117
4.5.4 Accelerating Rate Calorimeter (ARC) 119
4.5.4.1 Measurement Principle 119
4.5.4.2 Applications 120
4.5.5 Vent Sizing Package (VSP) 121
4.6 Exercises 122
References 126
5 Assessment of the Energy Potential 131
5.1 Thermal Energy 132
5.1.1 Thermal Energy of Synthesis Reactions 132
5.1.2 Energy Potential of Secondary Reactions 133
5.1.2.1 Typical Energies of Decomposition 134
5.1.2.2 Stoichiometry of Decomposition Reactions 134
5.1.2.3 Estimation of Decomposition Energies 135
5.1.2.4 Specific Problems Linked with Secondary Reactions 135
5.1.3 Adiabatic Temperature Rise 136
5.2 Pressure Effects 137
5.2.1 Gas Release 137
5.2.2 Vapor Pressure 138
5.2.3 Amount of Solvent Evaporated 139
5.3 Experimental Determination of Energy Potentials 140
5.3.1 Experimental Techniques 140
5.3.2 Choosing the Sample to be Analyzed 141
5.3.2.1 Sample Purity 141
5.3.2.2 Batch or Semi-Batch Process 142
5.3.2.3 Intermediates 144
5.3.3 Assessment of Process Deviations 144
5.3.3.1 Effect of Charging Errors 144
5.3.3.2 Effect of Solvents on Thermal Stability 146
5.3.3.3 Catalytic Effects of Impurities 146
5.4 Exercises 147
References 149
Part II Mastering Exothermal Reactions 153
6 General Aspects of Reactor Safety 155
6.1 Dynamic Stability of Reactors 157
6.1.1 Parametric Sensitivity 157
6.1.2 Sensitivity Toward Temperature: Reaction Number B 157
6.1.3 Heat Balance 158
6.1.3.1 The Semenov Criterion 159
6.1.3.2 Stability Diagrams 159
6.1.3.3 Heat Release Rate and Cooling Rate 159
6.1.3.4 Using Dimensionless Criteria 160
6.1.3.5 Chaos Theory and Lyapunov Exponents 162
6.1.3.6 Topological Tools 163
6.2 Reactor Safety After a Cooling Failure 163
6.2.1 Potential of the Reaction, the Adiabatic Temperature Rise 163
6.2.2 Temperature in Case of Cooling Failure: The Concept of MTSR 164
6.3 Example Reaction System 165
References 168
7 Batch Reactors 171
7.1 Chemical Reaction Engineering Aspects of Batch Reactors 172
7.1.1 Principles of Batch Reaction 172
7.1.2 Mass Balance 173
7.1.3 Heat Balance 174
7.1.4 Strategies of Temperature Control 174
7.2 Isothermal Reactions 175
7.2.1 Principles 175
7.2.2 Design of Safe Isothermal Reactors 175
7.2.3 Safety Assessment 178
7.3 Adiabatic Reaction 178
7.3.1 Principles 178
7.3.2 Design of a Safe Adiabatic Batch Reactor 178
7.3.3 Safety Assessment 179
7.4 Polytropic Reaction 179
7.4.1 Principles 179
7.4.2 Design of Polytropic Operation: Temperature Control 180
7.4.3 Safety Assessment 184
7.5 Isoperibolic Reaction 184
7.5.1 Principles 184
7.5.2 Design of Isoperibolic Operation: Temperature Control 184
7.5.3 Safety Assessment 184
7.6 Temperature-Controlled Reaction 185
7.6.1 Principles 185
7.6.2 Design of Temperature-Controlled Reaction 186
7.6.3 Safety Assessment 187
7.7 Key Factors for the Safe Design of Batch Reactors 188
7.7.1 Determination of Safety Relevant Data 188
7.7.2 Rules for Safe Operation of Batch Reactors 190
7.8 Exercises 193
References 195
8 Semi-batch Reactors 197
8.1 Principles of Semi-batch Reaction 198
8.1.1 Definition of Semi-batch Operation 198
8.1.2 Material Balance 199
8.1.3 Heat Balance of Semi-batch Reactors 200
8.1.3.1 Heat Production 200
8.1.3.2 Thermal Effect of the Feed 201
8.1.3.3 Heat Removal 201
8.1.3.4 Heat Accumulation 201
8.2 Reactant Accumulation in Semi-batch Reactors 202
8.2.1 Fast Reactions 203
8.2.2 Slow Reactions 205
8.2.3 Design of Safe Semi-batch Reactors 207
8.3 Isothermal Reaction 208
8.3.1 Principles of Isothermal Semi-batch Operation 208
8.3.2 Design of Isothermal Semi-batch Reactors 208
8.3.3 Accumulation with Complex Reactions 212
8.4 Isoperibolic, Constant Cooling Medium Temperature 212
8.5 Non-isothermal Reaction 214
8.6 Strategies of Feed Control 215
8.6.1 Addition by Portions 215
8.6.2 Constant Feed Rate 215
8.6.3 Interlock of Feed with Temperature 217
8.6.4 Why Reducing the Accumulation 219
8.7 Choice of Temperature and Feed Rate 219
8.7.1 General Principle 219
8.7.2 Scale-Up from Laboratory to Industrial Scale 220
8.7.3 Online Detection of Unwanted Accumulation 221
8.8 Advanced Feed Control 222
8.8.1 Feed Control by the Accumulation 222
8.8.2 Feed Control by the Thermal Stability 224
8.9 Exercises 226
References 228
9 Continuous Reactors 231
9.1 Continuous Stirred Tank Reactors 232
9.1.1 Mass Balance 233
9.1.2 Heat Balance 233
9.1.3 Cooled CSTR 234
9.1.4 Adiabatic CSTR 234
9.1.5 The Autothermal CSTR 236
9.1.6 Safety Aspects 237
9.1.6.1 Instabilities at Start-Up or Shutdown 237
9.1.6.2 Behavior in Case of Cooling Failure 237
9.2 Tubular Reactors 240
9.2.1 Mass Balance 240
9.2.2 Heat Balance 241
9.2.3 Safety Aspects 242
9.2.3.1 Parametric Sensitivity 242
9.2.3.2 Heat Exchange Capacities of Tubular Reactors 243
9.2.3.3 Passive Safety Aspects of Tubular Reactors 245
9.2.4 Performance and Safety Characteristics of Ideal Reactors 246
9.3 Other Continuous Reactor Types 247
9.3.1 Cascade of CSTRs 248
9.3.2 Recycling Reactor 248
9.3.3 Microreactors 249
9.3.4 Process Intensification 251
9.4 Exercises 252
References 253
Part III Avoiding Secondary Reactions 255
10 Thermal Stability 257
10.1 Thermal Stability and Secondary Decomposition Reactions 258
10.2 Triggering Conditions 260
10.2.1 Onset: A ConceptWithout Scientific Base 260
10.2.2 Decomposition Kinetics, the tmrad Concept 261
10.2.3 Safe Temperature 262
10.2.4 Assessment Procedure 262
10.3 Estimation ofThermal Stability 264
10.3.1 Estimation of TD24 from One Dynamic DSC Experiment 264
10.3.2 Conservative Extrapolation 264
10.3.3 Empirical Rules for the Determination of a “Safe” Temperature 267
10.3.4 Prediction of Thermal Stability 268
10.4 Quantitative Determination of the TD24 269
10.4.1 Principle of Quantitative DeterminationMethods for the Heat Release
Rate 269
10.4.2 Determination of q′ = f (T) from Isothermal Experiments 269
10.4.3 Determination of q′ = f (T) from Dynamic Experiments 273
10.4.4 Determination of TD24 275
10.5 Practice ofThermal Stability Assessment 276
10.5.1 Complex Reactions 276
10.5.2 Remarks on the Quality of Experiments and Evaluation 278
10.6 Exercises 278
References 281
11 Autocatalytic Reactions 283
11.1 Autocatalytic Decompositions 284
11.1.1 Definitions 284
11.1.1.1 Autocatalysis 284
11.1.1.2 Induction Time 284
11.1.2 Behavior of Autocatalytic Reactions 285
11.1.3 Rate Equations of Autocatalytic Reactions 286
11.1.3.1 The Prout–Tompkins Model 287
11.1.3.2 The Benito–Perez Model 288
11.1.3.3 The Berlin Model 288
11.1.4 Phenomenological Aspects of Autocatalytic Reactions 289
11.2 Identification of Autocatalytic Reactions 291
11.2.1 Chemical Information 291
11.2.2 Qualitative Peak Shape in a Dynamic DSC Thermogram 292
11.2.3 Quantitative Peak Shape Characterization 293
11.2.4 Double Scan Test 294
11.2.5 Identification by Isothermal DSC 296
11.3 Determination of tmrad of Autocatalytic Reactions 296
11.3.1 One-Point Estimation 296
11.3.2 Characterization Using Zero-Order Kinetics 297
11.3.3 Characterization Using a Mechanistic Approach 299
11.3.4 Characterization by Isoconversional Methods 301
11.3.5 Characterization by Adiabatic Calorimetry 302
11.4 Practical Safety Aspects for Autocatalytic Reactions 306
11.4.1 Specific Safety Aspects of Autocatalytic Reactions 306
11.4.2 Autocatalytic Decompositions in the Industrial Practice 307
11.4.3 Volatile Products as Catalysts 307
11.5 Exercises 308
References 309
12 Heat Accumulation 311
12.1 Heat Accumulation Situations 312
12.2 Heat Balance 313
12.2.1 Heat Balance Using Time Scale 314
12.2.2 Forced Convection, the SemenovModel 314
12.2.3 Natural Convection 315
12.2.4 High Viscosity Liquids, Pastes, and Solids 316
12.3 Heat Balance with Reactive Material 318
12.3.1 Conduction in a Reactive Solid with a Heat Source, the
Frank-Kamenetskii Model 318
12.3.2 Conduction in a Reactive Solid with Temperature Gradient at theWall,
the Thomas Model 323
12.3.3 Conduction in a Reactive Solid with Formal Kinetics, the Finite
Elements Model 324
12.4 Assessing Heat Accumulation Conditions 325
12.4.1 Thermal Explosion Models 325
12.4.2 Assessment Procedure 326
12.5 Exercises 332
References 333
13 Physical Unit Operations 335
13.1 Thermal Hazards in Physical Unit Operations 336
13.1.1 Introduction to Physical Unit Operations 336
13.1.2 Hazards in Physical Unit Operations 337
13.1.3 Assessment Procedure for Unwanted Exothermal Reactions 337
13.1.4 Specificities of Physical Unit Operations 338
13.1.5 Standardization of the Risk Assessment 338
13.2 Specific Testing Procedures 338
13.2.1 Shock Sensitivity: The Falling Hammer Test 339
13.2.2 Friction Sensitivity 339
13.2.3 DSC Dynamic 339
13.2.4 Decomposition Gases 340
13.2.5 Dynamic Decomposition Test (RADEX) 340
13.2.6 Mini Autoclave 341
13.2.7 Spontaneous Decomposition 341
13.2.7.1 Deflagration Tube 341
13.2.7.2 Test in Dewar 341
13.2.8 Grewer Oven and Decomposition in Airstream 342
13.2.9 RADEX Isoperibolic Test 342
13.2.10 Self-Ignition Test in a 400 ml Basket 342
13.2.11 Warm Storage Test in a Dewar 343
13.3 Hazards Associated to Solid Processing 343
13.3.1 Pneumatic and Mechanical Conveying Operations 343
13.3.2 Blending 343
13.3.3 Storage 344
13.3.4 Drying 344
13.3.4.1 Paddle Dryer 344
13.3.4.2 Fluidized Bed 345
13.3.5 Milling and Grinding 345
13.3.6 Hot Discharge 346
13.4 Hazards During Liquid Processing 346
13.4.1 Transport Operations 346
13.4.2 Operations with Heat Exchange 347
13.4.3 Evaporation and Distillation 348
13.4.3.1 Batch Distillation from a Stirred Tank 349
13.4.3.2 Continuous Distillation 349
13.4.4 Failure Modes of Heat Exchangers and Evaporators 350
13.4.5 Risk Reducing Measures 352
13.5 Transport of Dangerous Goods and SADT 353
13.6 Exercises 354
References 356
Part IV Technical Aspects of Thermal Process Safety 357
14 Heating and Cooling Industrial Reactors 359
14.1 Temperature Control of Industrial Reactors 361
14.1.1 Technical Heat Carriers 361
14.1.1.1 Steam Heating 361
14.1.1.2 HotWater Heating 362
14.1.1.3 Other Heating Media 363
14.1.1.4 Electrical Heating 363
14.1.1.5 Cooling with Ice 363
14.1.1.6 Other Heat Carriers for Cooling 363
14.1.2 Heating and Cooling Techniques 364
14.1.2.1 Direct Heating and Cooling 364
14.1.2.2 Indirect Heating and Cooling 364
14.1.2.3 Single Heat Carrier Circulation Systems 365
14.1.2.4 Secondary Circulation Loop Temperature Control Systems 368
14.1.3 Temperature Control Strategies 368
14.1.3.1 Isoperibolic Temperature Control 368
14.1.3.2 Isothermal Control 369
14.1.3.3 Isothermal Control at Reflux 369
14.1.3.4 Non-isothermal Temperature Control 370
14.1.4 Dynamic Aspects of Heat Exchange Systems 371
14.1.4.1 Thermal Time Constant 371
14.1.4.2 Heating and Cooling Time 373
14.1.4.3 Cascade Controller 374
14.2 Heat Exchange Across theWall 375
14.2.1 Two Film Theory 375
14.2.2 The Internal Film Coefficient of a Stirred Tank 376
14.2.3 Determination of the Internal Film Coefficient 376
14.2.4 The Resistance of the Equipment to Heat Transfer 378
14.2.5 Practical Determination of Heat Transfer Coefficients 379
14.3 Evaporative Cooling 382
14.3.1 Amount of Solvent Evaporated 383
14.3.2 Vapor Flow Rate 383
14.3.3 Flooding of the Vapor Tube 384
14.3.4 Swelling of the Reaction Mass 385
14.3.5 Practical Procedure for the Assessment of Reactor Safety at the Boiling
Point 386
14.4 Dynamics of the Temperature Control System and Process
Design 388
14.4.1 Background 388
14.4.2 Modeling the Dynamic Behavior of Industrial Reactors 389
14.4.3 Experimental Simulation of Industrial Reactors 390
14.5 Exercises 391
References 395
15 Risk Reducing Measures 397
15.1 Strategies of Choice 399
15.2 EliminatingMeasures 400
15.3 Technical PreventiveMeasures 401
15.3.1 Control of Feed 401
15.3.2 Emergency Cooling 402
15.3.3 Quenching and Flooding 403
15.3.4 Dumping 404
15.3.5 Controlled Depressurization 405
15.3.6 Alarm Systems 406
15.3.7 Time Factor 407
15.4 Emergency Measures 408
15.4.1 Emergency Pressure Relief Systems 408
15.4.2 Containment 408
15.5 Design of Technical Measures 409
15.5.1 Consequences of Runaway 409
15.5.1.1 Temperature 409
15.5.1.2 Pressure 409
15.5.1.3 Release 409
15.5.1.4 Closed Gassy Systems 410
15.5.1.5 Closed Vapor Systems 410
15.5.1.6 Open Gassy Systems 411
15.5.1.7 Open Vapor Systems 411
15.5.1.8 Extended Assessment Criteria for Severity 411
15.5.2 Controllability 412
15.5.2.1 Activity of the Main Reaction 412
15.5.2.2 Activity of Secondary Reactions 413
15.5.2.3 Gas Release Rate 414
15.5.2.4 Vapor Release Rate 414
15.5.2.5 Extended Assessment Criteria for the Controllability 415
15.5.3 Assessment of Severity and Probability for the Different Criticality
Classes 415
15.5.3.1 Criticality Class 1 416
15.5.3.2 Criticality Class 2 416
15.5.3.3 Criticality Class 3 416
15.5.3.4 Criticality Class 4 417
15.5.3.5 Criticality Class 5 418
15.6 Exercises 423
References 425
16 Emergency Pressure Relief 427
16.1 General Remarks on Emergency Relief Systems 429
16.1.1 Position of Emergency Relief Systems in a Protection Strategy 429
16.1.2 Regulatory Aspects 429
16.1.3 Protection Devices 430
16.1.3.1 Bursting Disks 430
16.1.3.2 Safety Valves 430
16.1.3.3 Combined Systems 430
16.1.3.4 Other Systems 431
16.1.4 Sizing Methods 432
16.2 Preliminary Steps of the Sizing Procedure: The Scenario 432
16.2.1 Step 1: Definition of the Design Case 432
16.2.2 Step 1: Quantifying the Relief Scenario 434
16.2.2.1 Volume Displacement 434
16.2.2.2 External Heating: Fire Cases 434
16.2.2.3 External Heating: Maximum Heating 434
16.2.2.4 Chemical ScenarioWithout Gas Release 435
16.2.2.5 Chemical Scenario with Gas Release 435
16.2.3 Step 2: Determination of the Flow Behavior 437
16.3 Sizing Steps: Fluid Dynamics 439
16.3.1 Step 3: Mass Flow Rate to Be Discharged 439
16.3.1.1 Mass Flow Rate for Vapor Relief with One-Phase Flow 439
16.3.1.2 Mass Flow Rate for Vapor Relief with Two-Phase Flow 440
16.3.1.3 Mass Flow Rate for Gas Relief with One- or Two-Phase Flow 440
16.3.1.4 Mass Flow Rate for Hybrid Systems with Two-Phase Flow 440
16.3.2 Step 4: Dischargeable Mass Flux Through an Ideal Nozzle 441
16.3.2.1 One-Phase Flow 441
16.3.2.2 Two-Phase Flow 441
16.3.3 Step 5 for Bursting Disk: Correction for Friction Losses 442
16.3.4 Step 6 for Bursting Disk: Calculation of the Required Relief Area 444
16.3.5 Step 5 for Safety Valve: Calculation of the Required Relief Area 444
16.3.6 Step 6 for SV: Checking Function Stability 445
16.3.6.1 Calculation of the Actual Mass Flow Rate in a Safety Valve 445
16.3.6.2 Calculation of the Inlet Pressure Loss 445
16.3.6.3 Calculation of Friction Losses Downstream a Safety Valve 446
16.4 Sizing ERS for Multipurpose Reactors 446
16.4.1 Principle of Sizing Procedure 446
16.4.2 Choice of the Sizing Scenario 447
16.4.3 Sensitivity Analysis of the Design Data 447
16.4.4 Checking the Relief Capacity 449
16.5 Effluent Treatment 450
16.5.1 Initial Design Step 451
16.5.2 Total Containment 451
16.5.3 Passive Condenser 451
16.5.4 Catch Tank, Gravity Separator 452
16.5.5 Cyclone 452
16.5.6 Quench Tank 452
16.6 Exercises 452
References 458
17 Reliability of Risk Reducing Measures 461
17.1 Basics of Reliability Engineering 463
17.1.1 Definitions 463
17.1.1.1 Process Control and Protection Systems 463
17.1.1.2 Reliability 464
17.1.1.3 Failures 464
17.1.2 Failure Frequency 465
17.1.3 Failures on the Time Scale 467
17.2 Reliability of Process Control Systems 468
17.2.1 Safety Integrity Level 468
17.2.2 Control Loops 468
17.2.3 Increasing the Reliability of an SIS 469
17.3 Practice of Reliability Assessment 469
17.3.1 Scenario Structure 469
17.3.2 Risk Matrix 470
17.3.3 Risk Reduction 471
17.3.4 Other Methods for Reliability Analysis 473
17.3.4.1 The Calibrated Risk Graph 473
17.3.4.2 The Layer of Protection Analysis 475
17.4 Exercises 475
References 476
18 Development of Safe Processes 479
18.1 Inherently Safer Processes 480
18.1.1 Principles of Inherent Safety 480
18.1.2 Safety Along Life Cycle of a Process 482
18.1.3 Developing a Safe Process 483
18.2 Methodological Approach 484
18.2.1 Specificity of the Fine Chemicals Industry 484
18.2.2 Integrated Process Development 484
18.3 Practice of Integrated Process Development 485
18.3.1 Objectives and Data 485
18.3.2 Chemists and Engineers 487
18.3.3 Communication and Problem Solving 488
18.4 Concluding Remark 488
References 489
Solutions of Exercises 491
Symbols 529
Index 537
Acknowledgments xxv
Part I General Aspects of Thermal Process Safety 1
1 Introduction to Risk Analysis of Fine Chemical Processes 3
1.1 Chemical Industry and Safety 4
1.1.1 Chemical Industry and Society 4
1.1.1.1 Product Safety 4
1.1.1.2 Process Safety 5
1.1.1.3 Accidents and Risk Perception in Chemical Industry 5
1.1.2 Responsibility 6
1.1.3 Definitions and Concepts 7
1.1.3.1 Hazard 7
1.1.3.2 Risk 7
1.1.3.3 Safety 8
1.1.3.4 Security 8
1.1.3.5 Accepted Risk 8
1.2 Steps of Risk Analysis 8
1.2.1 Scope of Analysis 9
1.2.2 Safety Data Collection 10
1.2.3 Safe Conditions and Critical Limits 10
1.2.4 Identification of Deviations 10
1.2.5 Risk Assessment 11
1.2.6 Risk Matrixes 14
1.2.7 Risk-Reducing Measures 15
1.2.8 Residual Risk 17
1.3 Safety Data 17
1.3.1 Physical Properties 18
1.3.2 Chemical Properties 18
1.3.3 Toxicity 18
1.3.4 Ecotoxicity 20
1.3.5 Fire and Explosion Data 20
1.3.6 Interactions 21
1.4 Systematic Identification of Hazards 21
1.4.1 Checklist Method 22
1.4.2 Failure Mode and Effect Analysis 24
1.4.3 Hazard and Operability Study 24
1.4.4 Decision Table 26
1.4.5 Event Tree Analysis 26
1.4.6 Fault Tree Analysis 27
1.4.7 Brainstorming 29
1.5 The Practice of Risk Analysis 29
1.5.1 Preparing the Risk Analysis 29
1.5.2 The Risk Analysis Team 30
1.5.3 The Team Leader 30
1.5.4 Finalizing the Risk Analysis 31
1.6 Exercises 31
References 32
2 Fundamentals of Thermal Process Safety 35
2.1 Energy Potential 37
2.1.1 Thermal Energy 37
2.1.1.1 Heat of Reaction 37
2.1.1.2 Heat of Decomposition 38
2.1.1.3 Heat Capacity 39
2.1.1.4 Adiabatic Temperature Rise 40
2.1.2 Pressure Effects 41
2.2 Effect of Temperature on Reaction Rate 41
2.2.1 Single Reaction 41
2.2.2 Multiple Reactions 42
2.3 Heat Balance 43
2.3.1 Terms of the Heat Balance 43
2.3.1.1 Heat Production 43
2.3.1.2 Heat Removal 44
2.3.1.3 Heat Accumulation 46
2.3.1.4 Convective Heat Exchange Due to Mass Flow 46
2.3.1.5 Sensible Heat Due to Feed 47
2.3.1.6 Stirrer 47
2.3.1.7 Heat Losses 47
2.3.2 Simplified Expression of the Heat Balance 48
2.3.3 Reaction Rate Under Adiabatic Conditions 49
2.4 Runaway Reactions 50
2.4.1 Thermal Explosions 50
2.4.2 Semenov Diagram 51
2.4.3 Parametric Sensitivity 52
2.4.4 Critical Temperature 53
2.4.5 Sensitivity Toward Variation of the Coolant Temperature 55
2.4.6 Time Frame of aThermal Explosion, the tmrad Concept 56
2.5 Exercises 57
References 59
3 Assessment of Thermal Risks 61
3.1 Thermal Process Safety 62
3.1.1 Thermal Risks 62
3.1.2 Processes Concerned byThermal Risks 62
3.2 Thermal Risk Assessment Criteria 63
3.2.1 Cooling Failure Scenario 63
3.2.2 Severity 66
3.2.3 Probability 68
3.2.4 Runaway Risk Assessment 70
3.3 Criticality of Chemical Processes 70
3.3.1 Assessment of the Criticality 70
3.3.2 Criticality Classes 72
3.3.2.1 Criticality Class 1 72
3.3.2.2 Criticality Class 2 72
3.3.2.3 Criticality Class 3 73
3.3.2.4 Criticality Class 4 73
3.3.2.5 Criticality Class 5 73
3.3.3 Special Cases of Criticality Assessment 76
3.3.4 Remarks on Criticality Class 5 76
3.3.5 Using MTT as a Safety Barrier 77
3.4 Assessment Procedures 81
3.4.1 General Rules for Thermal Safety Assessment 81
3.4.2 Practical Procedure for the Assessment ofThermal Risks 81
3.5 Exercises 85
References 87
4 Experimental Techniques 89
4.1 CalorimetricMeasurement Principles 90
4.1.1 Classification of Calorimeters 90
4.1.2 Temperature Control Modes of Calorimeters 90
4.1.2.1 Isothermal Mode 91
4.1.2.2 Dynamic Mode 91
4.1.2.3 Adiabatic 91
4.1.2.4 Isoperibolic 92
4.1.3 Heat Balance in Calorimeters 92
4.1.3.1 Ideal Accumulation 93
4.1.3.2 Ideal Heat Flow 93
4.1.3.3 Isoperibolic Methods 94
4.2 Instruments Used in Safety Laboratories 94
4.2.1 Characteristics of Instruments Used for Safety Studies 94
4.2.1.1 Sample Mass 94
4.2.1.2 Sensitivity 96
4.2.1.3 Construction of the Calorimeter 96
4.2.1.4 Calorimetric Cells for Safety Studies 96
4.2.2 Example of Instruments Used for Safety Studies 97
4.3 Microcalorimeters 97
4.3.1 Differential Scanning Calorimetry (DSC) 97
4.3.1.1 Principles of DSC 98
4.3.1.2 DSC and Safety Studies 98
4.3.1.3 DSC Crucibles 99
4.3.1.4 Applications 100
4.3.1.5 Sample Preparation 102
4.3.1.6 The Baseline Problem 103
4.3.2 Calvet Calorimeters 104
4.3.2.1 Principle 104
4.3.2.2 Applications 105
4.3.3 Thermal ActivityMonitor 106
4.3.3.1 Principle 106
4.3.3.2 Applications 107
4.4 Reaction Calorimeters 107
4.4.1 Purpose of Reaction Calorimeters 107
4.4.2 Principles of Reaction Calorimeters 108
4.4.2.1 Heat Flow Calorimeters 108
4.4.2.2 Heat Balance Calorimeters 109
4.4.2.3 Compensation Calorimeters 109
4.4.2.4 The Baseline Problem 109
4.4.3 Examples of Reaction Calorimeters 110
4.4.3.1 RC1 by Mettler Toledo 110
4.4.3.2 CPA 202 by ChemiSens 111
4.4.3.3 Calo 2310 by Systag 111
4.4.3.4 Small-Scale Reaction Calorimeters 111
4.4.3.5 Reaction Calorimetry at Industrial Scale 111
4.4.3.6 Reaction Calorimetry at Microscale 111
4.4.4 Applications 113
4.4.4.1 Thermal Data of Reactions 113
4.4.4.2 Reaction Kinetics 114
4.5 Adiabatic Calorimeters 114
4.5.1 Principle of Adiabatic Calorimetry 114
4.5.2 On the Thermal Inertia 115
4.5.3 Dewar Calorimeters 116
4.5.3.1 Measurement Principle 116
4.5.3.2 Applications 117
4.5.4 Accelerating Rate Calorimeter (ARC) 119
4.5.4.1 Measurement Principle 119
4.5.4.2 Applications 120
4.5.5 Vent Sizing Package (VSP) 121
4.6 Exercises 122
References 126
5 Assessment of the Energy Potential 131
5.1 Thermal Energy 132
5.1.1 Thermal Energy of Synthesis Reactions 132
5.1.2 Energy Potential of Secondary Reactions 133
5.1.2.1 Typical Energies of Decomposition 134
5.1.2.2 Stoichiometry of Decomposition Reactions 134
5.1.2.3 Estimation of Decomposition Energies 135
5.1.2.4 Specific Problems Linked with Secondary Reactions 135
5.1.3 Adiabatic Temperature Rise 136
5.2 Pressure Effects 137
5.2.1 Gas Release 137
5.2.2 Vapor Pressure 138
5.2.3 Amount of Solvent Evaporated 139
5.3 Experimental Determination of Energy Potentials 140
5.3.1 Experimental Techniques 140
5.3.2 Choosing the Sample to be Analyzed 141
5.3.2.1 Sample Purity 141
5.3.2.2 Batch or Semi-Batch Process 142
5.3.2.3 Intermediates 144
5.3.3 Assessment of Process Deviations 144
5.3.3.1 Effect of Charging Errors 144
5.3.3.2 Effect of Solvents on Thermal Stability 146
5.3.3.3 Catalytic Effects of Impurities 146
5.4 Exercises 147
References 149
Part II Mastering Exothermal Reactions 153
6 General Aspects of Reactor Safety 155
6.1 Dynamic Stability of Reactors 157
6.1.1 Parametric Sensitivity 157
6.1.2 Sensitivity Toward Temperature: Reaction Number B 157
6.1.3 Heat Balance 158
6.1.3.1 The Semenov Criterion 159
6.1.3.2 Stability Diagrams 159
6.1.3.3 Heat Release Rate and Cooling Rate 159
6.1.3.4 Using Dimensionless Criteria 160
6.1.3.5 Chaos Theory and Lyapunov Exponents 162
6.1.3.6 Topological Tools 163
6.2 Reactor Safety After a Cooling Failure 163
6.2.1 Potential of the Reaction, the Adiabatic Temperature Rise 163
6.2.2 Temperature in Case of Cooling Failure: The Concept of MTSR 164
6.3 Example Reaction System 165
References 168
7 Batch Reactors 171
7.1 Chemical Reaction Engineering Aspects of Batch Reactors 172
7.1.1 Principles of Batch Reaction 172
7.1.2 Mass Balance 173
7.1.3 Heat Balance 174
7.1.4 Strategies of Temperature Control 174
7.2 Isothermal Reactions 175
7.2.1 Principles 175
7.2.2 Design of Safe Isothermal Reactors 175
7.2.3 Safety Assessment 178
7.3 Adiabatic Reaction 178
7.3.1 Principles 178
7.3.2 Design of a Safe Adiabatic Batch Reactor 178
7.3.3 Safety Assessment 179
7.4 Polytropic Reaction 179
7.4.1 Principles 179
7.4.2 Design of Polytropic Operation: Temperature Control 180
7.4.3 Safety Assessment 184
7.5 Isoperibolic Reaction 184
7.5.1 Principles 184
7.5.2 Design of Isoperibolic Operation: Temperature Control 184
7.5.3 Safety Assessment 184
7.6 Temperature-Controlled Reaction 185
7.6.1 Principles 185
7.6.2 Design of Temperature-Controlled Reaction 186
7.6.3 Safety Assessment 187
7.7 Key Factors for the Safe Design of Batch Reactors 188
7.7.1 Determination of Safety Relevant Data 188
7.7.2 Rules for Safe Operation of Batch Reactors 190
7.8 Exercises 193
References 195
8 Semi-batch Reactors 197
8.1 Principles of Semi-batch Reaction 198
8.1.1 Definition of Semi-batch Operation 198
8.1.2 Material Balance 199
8.1.3 Heat Balance of Semi-batch Reactors 200
8.1.3.1 Heat Production 200
8.1.3.2 Thermal Effect of the Feed 201
8.1.3.3 Heat Removal 201
8.1.3.4 Heat Accumulation 201
8.2 Reactant Accumulation in Semi-batch Reactors 202
8.2.1 Fast Reactions 203
8.2.2 Slow Reactions 205
8.2.3 Design of Safe Semi-batch Reactors 207
8.3 Isothermal Reaction 208
8.3.1 Principles of Isothermal Semi-batch Operation 208
8.3.2 Design of Isothermal Semi-batch Reactors 208
8.3.3 Accumulation with Complex Reactions 212
8.4 Isoperibolic, Constant Cooling Medium Temperature 212
8.5 Non-isothermal Reaction 214
8.6 Strategies of Feed Control 215
8.6.1 Addition by Portions 215
8.6.2 Constant Feed Rate 215
8.6.3 Interlock of Feed with Temperature 217
8.6.4 Why Reducing the Accumulation 219
8.7 Choice of Temperature and Feed Rate 219
8.7.1 General Principle 219
8.7.2 Scale-Up from Laboratory to Industrial Scale 220
8.7.3 Online Detection of Unwanted Accumulation 221
8.8 Advanced Feed Control 222
8.8.1 Feed Control by the Accumulation 222
8.8.2 Feed Control by the Thermal Stability 224
8.9 Exercises 226
References 228
9 Continuous Reactors 231
9.1 Continuous Stirred Tank Reactors 232
9.1.1 Mass Balance 233
9.1.2 Heat Balance 233
9.1.3 Cooled CSTR 234
9.1.4 Adiabatic CSTR 234
9.1.5 The Autothermal CSTR 236
9.1.6 Safety Aspects 237
9.1.6.1 Instabilities at Start-Up or Shutdown 237
9.1.6.2 Behavior in Case of Cooling Failure 237
9.2 Tubular Reactors 240
9.2.1 Mass Balance 240
9.2.2 Heat Balance 241
9.2.3 Safety Aspects 242
9.2.3.1 Parametric Sensitivity 242
9.2.3.2 Heat Exchange Capacities of Tubular Reactors 243
9.2.3.3 Passive Safety Aspects of Tubular Reactors 245
9.2.4 Performance and Safety Characteristics of Ideal Reactors 246
9.3 Other Continuous Reactor Types 247
9.3.1 Cascade of CSTRs 248
9.3.2 Recycling Reactor 248
9.3.3 Microreactors 249
9.3.4 Process Intensification 251
9.4 Exercises 252
References 253
Part III Avoiding Secondary Reactions 255
10 Thermal Stability 257
10.1 Thermal Stability and Secondary Decomposition Reactions 258
10.2 Triggering Conditions 260
10.2.1 Onset: A ConceptWithout Scientific Base 260
10.2.2 Decomposition Kinetics, the tmrad Concept 261
10.2.3 Safe Temperature 262
10.2.4 Assessment Procedure 262
10.3 Estimation ofThermal Stability 264
10.3.1 Estimation of TD24 from One Dynamic DSC Experiment 264
10.3.2 Conservative Extrapolation 264
10.3.3 Empirical Rules for the Determination of a “Safe” Temperature 267
10.3.4 Prediction of Thermal Stability 268
10.4 Quantitative Determination of the TD24 269
10.4.1 Principle of Quantitative DeterminationMethods for the Heat Release
Rate 269
10.4.2 Determination of q′ = f (T) from Isothermal Experiments 269
10.4.3 Determination of q′ = f (T) from Dynamic Experiments 273
10.4.4 Determination of TD24 275
10.5 Practice ofThermal Stability Assessment 276
10.5.1 Complex Reactions 276
10.5.2 Remarks on the Quality of Experiments and Evaluation 278
10.6 Exercises 278
References 281
11 Autocatalytic Reactions 283
11.1 Autocatalytic Decompositions 284
11.1.1 Definitions 284
11.1.1.1 Autocatalysis 284
11.1.1.2 Induction Time 284
11.1.2 Behavior of Autocatalytic Reactions 285
11.1.3 Rate Equations of Autocatalytic Reactions 286
11.1.3.1 The Prout–Tompkins Model 287
11.1.3.2 The Benito–Perez Model 288
11.1.3.3 The Berlin Model 288
11.1.4 Phenomenological Aspects of Autocatalytic Reactions 289
11.2 Identification of Autocatalytic Reactions 291
11.2.1 Chemical Information 291
11.2.2 Qualitative Peak Shape in a Dynamic DSC Thermogram 292
11.2.3 Quantitative Peak Shape Characterization 293
11.2.4 Double Scan Test 294
11.2.5 Identification by Isothermal DSC 296
11.3 Determination of tmrad of Autocatalytic Reactions 296
11.3.1 One-Point Estimation 296
11.3.2 Characterization Using Zero-Order Kinetics 297
11.3.3 Characterization Using a Mechanistic Approach 299
11.3.4 Characterization by Isoconversional Methods 301
11.3.5 Characterization by Adiabatic Calorimetry 302
11.4 Practical Safety Aspects for Autocatalytic Reactions 306
11.4.1 Specific Safety Aspects of Autocatalytic Reactions 306
11.4.2 Autocatalytic Decompositions in the Industrial Practice 307
11.4.3 Volatile Products as Catalysts 307
11.5 Exercises 308
References 309
12 Heat Accumulation 311
12.1 Heat Accumulation Situations 312
12.2 Heat Balance 313
12.2.1 Heat Balance Using Time Scale 314
12.2.2 Forced Convection, the SemenovModel 314
12.2.3 Natural Convection 315
12.2.4 High Viscosity Liquids, Pastes, and Solids 316
12.3 Heat Balance with Reactive Material 318
12.3.1 Conduction in a Reactive Solid with a Heat Source, the
Frank-Kamenetskii Model 318
12.3.2 Conduction in a Reactive Solid with Temperature Gradient at theWall,
the Thomas Model 323
12.3.3 Conduction in a Reactive Solid with Formal Kinetics, the Finite
Elements Model 324
12.4 Assessing Heat Accumulation Conditions 325
12.4.1 Thermal Explosion Models 325
12.4.2 Assessment Procedure 326
12.5 Exercises 332
References 333
13 Physical Unit Operations 335
13.1 Thermal Hazards in Physical Unit Operations 336
13.1.1 Introduction to Physical Unit Operations 336
13.1.2 Hazards in Physical Unit Operations 337
13.1.3 Assessment Procedure for Unwanted Exothermal Reactions 337
13.1.4 Specificities of Physical Unit Operations 338
13.1.5 Standardization of the Risk Assessment 338
13.2 Specific Testing Procedures 338
13.2.1 Shock Sensitivity: The Falling Hammer Test 339
13.2.2 Friction Sensitivity 339
13.2.3 DSC Dynamic 339
13.2.4 Decomposition Gases 340
13.2.5 Dynamic Decomposition Test (RADEX) 340
13.2.6 Mini Autoclave 341
13.2.7 Spontaneous Decomposition 341
13.2.7.1 Deflagration Tube 341
13.2.7.2 Test in Dewar 341
13.2.8 Grewer Oven and Decomposition in Airstream 342
13.2.9 RADEX Isoperibolic Test 342
13.2.10 Self-Ignition Test in a 400 ml Basket 342
13.2.11 Warm Storage Test in a Dewar 343
13.3 Hazards Associated to Solid Processing 343
13.3.1 Pneumatic and Mechanical Conveying Operations 343
13.3.2 Blending 343
13.3.3 Storage 344
13.3.4 Drying 344
13.3.4.1 Paddle Dryer 344
13.3.4.2 Fluidized Bed 345
13.3.5 Milling and Grinding 345
13.3.6 Hot Discharge 346
13.4 Hazards During Liquid Processing 346
13.4.1 Transport Operations 346
13.4.2 Operations with Heat Exchange 347
13.4.3 Evaporation and Distillation 348
13.4.3.1 Batch Distillation from a Stirred Tank 349
13.4.3.2 Continuous Distillation 349
13.4.4 Failure Modes of Heat Exchangers and Evaporators 350
13.4.5 Risk Reducing Measures 352
13.5 Transport of Dangerous Goods and SADT 353
13.6 Exercises 354
References 356
Part IV Technical Aspects of Thermal Process Safety 357
14 Heating and Cooling Industrial Reactors 359
14.1 Temperature Control of Industrial Reactors 361
14.1.1 Technical Heat Carriers 361
14.1.1.1 Steam Heating 361
14.1.1.2 HotWater Heating 362
14.1.1.3 Other Heating Media 363
14.1.1.4 Electrical Heating 363
14.1.1.5 Cooling with Ice 363
14.1.1.6 Other Heat Carriers for Cooling 363
14.1.2 Heating and Cooling Techniques 364
14.1.2.1 Direct Heating and Cooling 364
14.1.2.2 Indirect Heating and Cooling 364
14.1.2.3 Single Heat Carrier Circulation Systems 365
14.1.2.4 Secondary Circulation Loop Temperature Control Systems 368
14.1.3 Temperature Control Strategies 368
14.1.3.1 Isoperibolic Temperature Control 368
14.1.3.2 Isothermal Control 369
14.1.3.3 Isothermal Control at Reflux 369
14.1.3.4 Non-isothermal Temperature Control 370
14.1.4 Dynamic Aspects of Heat Exchange Systems 371
14.1.4.1 Thermal Time Constant 371
14.1.4.2 Heating and Cooling Time 373
14.1.4.3 Cascade Controller 374
14.2 Heat Exchange Across theWall 375
14.2.1 Two Film Theory 375
14.2.2 The Internal Film Coefficient of a Stirred Tank 376
14.2.3 Determination of the Internal Film Coefficient 376
14.2.4 The Resistance of the Equipment to Heat Transfer 378
14.2.5 Practical Determination of Heat Transfer Coefficients 379
14.3 Evaporative Cooling 382
14.3.1 Amount of Solvent Evaporated 383
14.3.2 Vapor Flow Rate 383
14.3.3 Flooding of the Vapor Tube 384
14.3.4 Swelling of the Reaction Mass 385
14.3.5 Practical Procedure for the Assessment of Reactor Safety at the Boiling
Point 386
14.4 Dynamics of the Temperature Control System and Process
Design 388
14.4.1 Background 388
14.4.2 Modeling the Dynamic Behavior of Industrial Reactors 389
14.4.3 Experimental Simulation of Industrial Reactors 390
14.5 Exercises 391
References 395
15 Risk Reducing Measures 397
15.1 Strategies of Choice 399
15.2 EliminatingMeasures 400
15.3 Technical PreventiveMeasures 401
15.3.1 Control of Feed 401
15.3.2 Emergency Cooling 402
15.3.3 Quenching and Flooding 403
15.3.4 Dumping 404
15.3.5 Controlled Depressurization 405
15.3.6 Alarm Systems 406
15.3.7 Time Factor 407
15.4 Emergency Measures 408
15.4.1 Emergency Pressure Relief Systems 408
15.4.2 Containment 408
15.5 Design of Technical Measures 409
15.5.1 Consequences of Runaway 409
15.5.1.1 Temperature 409
15.5.1.2 Pressure 409
15.5.1.3 Release 409
15.5.1.4 Closed Gassy Systems 410
15.5.1.5 Closed Vapor Systems 410
15.5.1.6 Open Gassy Systems 411
15.5.1.7 Open Vapor Systems 411
15.5.1.8 Extended Assessment Criteria for Severity 411
15.5.2 Controllability 412
15.5.2.1 Activity of the Main Reaction 412
15.5.2.2 Activity of Secondary Reactions 413
15.5.2.3 Gas Release Rate 414
15.5.2.4 Vapor Release Rate 414
15.5.2.5 Extended Assessment Criteria for the Controllability 415
15.5.3 Assessment of Severity and Probability for the Different Criticality
Classes 415
15.5.3.1 Criticality Class 1 416
15.5.3.2 Criticality Class 2 416
15.5.3.3 Criticality Class 3 416
15.5.3.4 Criticality Class 4 417
15.5.3.5 Criticality Class 5 418
15.6 Exercises 423
References 425
16 Emergency Pressure Relief 427
16.1 General Remarks on Emergency Relief Systems 429
16.1.1 Position of Emergency Relief Systems in a Protection Strategy 429
16.1.2 Regulatory Aspects 429
16.1.3 Protection Devices 430
16.1.3.1 Bursting Disks 430
16.1.3.2 Safety Valves 430
16.1.3.3 Combined Systems 430
16.1.3.4 Other Systems 431
16.1.4 Sizing Methods 432
16.2 Preliminary Steps of the Sizing Procedure: The Scenario 432
16.2.1 Step 1: Definition of the Design Case 432
16.2.2 Step 1: Quantifying the Relief Scenario 434
16.2.2.1 Volume Displacement 434
16.2.2.2 External Heating: Fire Cases 434
16.2.2.3 External Heating: Maximum Heating 434
16.2.2.4 Chemical ScenarioWithout Gas Release 435
16.2.2.5 Chemical Scenario with Gas Release 435
16.2.3 Step 2: Determination of the Flow Behavior 437
16.3 Sizing Steps: Fluid Dynamics 439
16.3.1 Step 3: Mass Flow Rate to Be Discharged 439
16.3.1.1 Mass Flow Rate for Vapor Relief with One-Phase Flow 439
16.3.1.2 Mass Flow Rate for Vapor Relief with Two-Phase Flow 440
16.3.1.3 Mass Flow Rate for Gas Relief with One- or Two-Phase Flow 440
16.3.1.4 Mass Flow Rate for Hybrid Systems with Two-Phase Flow 440
16.3.2 Step 4: Dischargeable Mass Flux Through an Ideal Nozzle 441
16.3.2.1 One-Phase Flow 441
16.3.2.2 Two-Phase Flow 441
16.3.3 Step 5 for Bursting Disk: Correction for Friction Losses 442
16.3.4 Step 6 for Bursting Disk: Calculation of the Required Relief Area 444
16.3.5 Step 5 for Safety Valve: Calculation of the Required Relief Area 444
16.3.6 Step 6 for SV: Checking Function Stability 445
16.3.6.1 Calculation of the Actual Mass Flow Rate in a Safety Valve 445
16.3.6.2 Calculation of the Inlet Pressure Loss 445
16.3.6.3 Calculation of Friction Losses Downstream a Safety Valve 446
16.4 Sizing ERS for Multipurpose Reactors 446
16.4.1 Principle of Sizing Procedure 446
16.4.2 Choice of the Sizing Scenario 447
16.4.3 Sensitivity Analysis of the Design Data 447
16.4.4 Checking the Relief Capacity 449
16.5 Effluent Treatment 450
16.5.1 Initial Design Step 451
16.5.2 Total Containment 451
16.5.3 Passive Condenser 451
16.5.4 Catch Tank, Gravity Separator 452
16.5.5 Cyclone 452
16.5.6 Quench Tank 452
16.6 Exercises 452
References 458
17 Reliability of Risk Reducing Measures 461
17.1 Basics of Reliability Engineering 463
17.1.1 Definitions 463
17.1.1.1 Process Control and Protection Systems 463
17.1.1.2 Reliability 464
17.1.1.3 Failures 464
17.1.2 Failure Frequency 465
17.1.3 Failures on the Time Scale 467
17.2 Reliability of Process Control Systems 468
17.2.1 Safety Integrity Level 468
17.2.2 Control Loops 468
17.2.3 Increasing the Reliability of an SIS 469
17.3 Practice of Reliability Assessment 469
17.3.1 Scenario Structure 469
17.3.2 Risk Matrix 470
17.3.3 Risk Reduction 471
17.3.4 Other Methods for Reliability Analysis 473
17.3.4.1 The Calibrated Risk Graph 473
17.3.4.2 The Layer of Protection Analysis 475
17.4 Exercises 475
References 476
18 Development of Safe Processes 479
18.1 Inherently Safer Processes 480
18.1.1 Principles of Inherent Safety 480
18.1.2 Safety Along Life Cycle of a Process 482
18.1.3 Developing a Safe Process 483
18.2 Methodological Approach 484
18.2.1 Specificity of the Fine Chemicals Industry 484
18.2.2 Integrated Process Development 484
18.3 Practice of Integrated Process Development 485
18.3.1 Objectives and Data 485
18.3.2 Chemists and Engineers 487
18.3.3 Communication and Problem Solving 488
18.4 Concluding Remark 488
References 489
Solutions of Exercises 491
Symbols 529
Index 537