Understanding explosions

PREFACE ix ACKNOWLEDGMENTS xi 1 INTRODUCTION 1 1.1. Acci dent Loss His tory 3 1.2. The Acci dent Pro cess (AIChE, 2000) 4 1.3. A Case His tory—Flixborough, Eng land 4 1.4. Hazard Iden ti fi ca tion and Eval u a tion 6 1.5. Inher ently Safer Design 7 2 FUNDAMENTALS OF FIRES AND EXPLOSIONS 9 2.1. Gases and Vapors 13 2.1.1. Flammability Dia gram 18 2.1.2. Estimating Flammability Limits 28 2.1.3. Tem per a ture Effect on Flammability 30 2.1.4. Pres sure Effect on Flammability 31 2.1.5. Flammability of Gas eous Mix tures 31 2.1.6. Min i mum Igni tion Ener gies 32 2.1.7. Autoignition Tem per a ture 34 2.1.8. Exam ple Appli ca tions 34 2.2. Liq uids 37 2.2.1. Flashpoints of Mix tures of Liq uids 40 2.2.2. Exam ple Appli ca tions 42 2.3. Aero sols and Mists 43 v 2.4. Dusts 43 2.5. Hybrid Mix tures 48 2.6. Kinet ics and Thermochemistry 48 2.6.1. Cal cu lated Adi a batic Flame Tem per a tures (CAFT) 50 2.6.2. Exam ple Appli ca tion 52 2.7. Gas Dynam ics 54 2.7.1. Det o na tions and Def la gra tions 58 2.7.2. Esti mat ing Peak Side-on Overpressures 61 2.7.3. Exam ple Appli ca tions 62 2.7.4. Pres sure Piling and Def la gra tion to Det o na tion Tran si tion 63 2.8. Phys i cal Explo sions 64 2.8.1. BLEVEs 65 2.8.2. Rapid Phase Tran si tion Explo sions 67 2.9. Vapor Cloud Explo sions 68 2.9.1. TNT Equiv a lency 70 2.9.2. TNO Multi-Energy Method 71 2.9.3. Baker–Strehlow–Tang Method (AIChE, 1999a) 77 2.9.4. Com pu ta tional Fluid Mechan ics (CFD) Method 82 2.9.5. Exam ple Appli ca tions 83 2.10. Run away Reac tions 85 2.10.1. Steady-State and Dynamic Reac tor Behav ior 88 2.10.2. Exper i men tal Char ac ter iza tion 92 2.11. Con densed Phase Explo sions 94 2.12. Fire balls, Pool, Flash, and Jet Fires 96 2.13. Explo sion Effects 98 2.13.1. Ther mal Expo sure 98 2.13.2. Overpressure Expo sure 99 2.14. Igni tion Sources 103 2.14.1. Static Electricity 105 3 PREVENTION AND MITIGATION OF EXPLOSIONS 113 3.1. Addi tional Ref er ences 113 3.2. Inher ently Safer Design 113 3.3. Using the Flammability Dia gram to Avoid Flam ma ble Atmo spheres 117 vi Contents 3.4. Inerting and Purg ing 120 3.4.1. Vacuum Purg ing 121 3.4.2. Pres sure Purg ing 123 3.4.3. Com bined Pres sure–Vacuum Purg ing 124 3.4.4. Sweep Purg ing 126 3.4.5. Siphon Purg ing 127 3.4.6. Advan tages and Dis ad van tages of the Var i ous Inerting Pro ce dures 127 3.4.7. Inert Gas Blan ket ing of Stor age Ves sels 128 3.4.8. Inert Purg ing and Blan ket ing during Drum ming Oper a tions 128 3.5. Exam ple Appli ca tion 130 3.6. Explo sion Vent ing 132 3.7. Ground ing and Bond ing 132 3.8. Ven ti la tion 138 3.9. Sprin kler and Deluge Sys tems 139 3.10. Charg ing and Drum ming Flam ma ble Liq uids 142 3.11. Exam ple Appli ca tion 142 3.12. Charg ing Pow ders 145 3.13. Elec tri cal Equip ment in Haz ard ous (Clas si fied) Areas 148 3.13.1. Pro tec tion Tech niques 156 Appendix A DETAILED EQUATIONS FOR FLAMMABILITY DIAGRAMS 161 Part A: Equa tions Useful for Gas Mix tures 161 Part B: Equa tions Useful for Plac ing Ves sels Into and Out of Ser vice 165 Appendix B EQUATIONS FOR DETERMINING THE ENERGY OF EXPLOSION 169 B.1. Exam ple Appli ca tion 171 Appendix C FLAMMABILITY DATA FOR SELECTED MATERIALS 173 Contents vii Appendix D PROCEDURE FOR EXAMPLE 3.2 177 Appendix E COMBUSTION DATA FOR DUST CLOUDS 191 REFERENCES 193 GLOSSARY 203 INDEX 209