Dust Explosions

ISBN-13: 9781461568711 / Angielski / Miękka / 2012 / 260 str.

Jean Cross; Donald Farrer

Opis

The interest of the media in dust explosions increased considerably following two major grain-elevator disasters in the United States in 1979. However, these were not isolated incidents and were statistically unusual only in the high loss of life involved. Any oxidizable material that is dispersed in fine powder form may be explosive, and ignition sources with sufficient energy to ignite a dust cloud are easily produced in normal industrial processing. Dust fires and minor incidents are not uncommon in many industries, but fortunately the combination of events and circumstances that must coincide for a large-scale explosion arise only rarely. Nevertheless, this is often more by luck than by good management and many potentially hazardous situations are common in industry. An explosive dust cloud and the circumstances in which it can ignite are not as simple to define as the equivalent situation in gases or flammable vapors. A large number of definitions and experimental tests have been devised to characterize the explosibility of dusts and ignition sources. The aim of this book is to provide a guide describing conditions in industry that could lead to dust explosions and the means to avoid them. Ignition sources and the way in which they can arise in powder processing are discussed and illustrated by case histories of reported incidents. The methods by which the potential hazards of a process or product can be evaluated are described, with special attention paid to the interpretation of the results of the different experimental methods.

Spis treści

1. Introduction.- 1.1. How, Where, and Why Dust Ignitions Occur.- 1.2. Ignition Sources—Statistical Data.- 1.3. Ignition Sources.- 1.4. Ignition Properties of Powdered Materials.- 1.5. Dust-Classification Systems.- 1.6. Protection Systems.- 1.7. General Considerations.- 2. Ignition Sources.- 2.1. Welding, Cutting, and Flames.- 2.2. Self-Heating—Spontaneous Combustion.- 2.3. Hot Surfaces.- 2.4. Sparks.- 2.5. Secondary Ignition.- 3. Static Electricity.- 3.1. Introduction.- 3.2. Definitions and Relationships.- 3.3. Measurement Techniques.- 3.4. Examples of Electrostatic Measurements in an Industrial Environment.- 4. Electrostatic Ignition of Powders.- 4.1. Electrostatic Charging of Powders.- 4.2. Electrostatic Charge Accumulation.- 4.3. Electrostatic Safety Criteria.- 4.4. Elimination of Static.- 4.5. Electric Shock.- 4.6. Safety in Electrostatic Powder-Coating Systems.- 5. Powder Properties and Their Measurement.- 5.1. Introduction.- 5.2. General Properties—Particle Size and Shape.- 5.3. Dust Resistivity.- 5.4. Moisture Content.- 5.5. Dust Concentration in the Workplace.- 5.6. Ignitability.- 5.7. Thermal Tests.- 5.8. Minimum Ignition Energy.- 5.9. Minimum Explosive Concentration.- 5.10. Maximum Oxygen Concentration.- 5.11. Maximum Rate of Pressure Rise; Maximum Explosive Pressure.- 5.12. Effect of Particle Properties on Ignition Properties.- 5.13. Effect of Hot Environments on Ignition Parameters.- 5.14. Summary.- 6. Design of a Processing Plant for Safety.- 6.1. Formal Safety Analysis.- 6.2. Hazards Associated with Industrial Processes.- 6.3. The Human Element.- 6.4. Dust Control.- 7. Dust Explosion Protection.- 7.1. Introduction.- 7.2. Containment of Explosions.- 7.3. Explosion Venting—Pressure Relief for Explosion Protection.- 7.4. Explosion Suppression.- 7.5. Inerting.- 7.6. Flame Traps and Automatic Barriers.- Appendixes.- A1. Summary of Electrostatic Equations.- A2. Certification and Standards.- A3. Sources of Explosion Data.- B1. Fire.- B2. Dust Explosions—General.- B3. Industrial Processes.- B4. Plant Layout.- B5. Hazard Analysis.- B6. Test Methods.- B7. Welding.- B8. Electrostatics.- B9. Impact Sparks.- B10. Electrical Equipment.- B11. Thermal Ignition.- B12. Venting of Plant.- B13. Venting of Buildings.- B14. Suppression.- B15. Inerting.- B16. Case Histories.- References.