Page 15 - Dust Explosions in the Process Industries

xii Dust Explosions in the Process Industries

6.2.4 Experiments in Japan on venting of dust explosions
in a 0.32 m3cyclone 444
6.2.5 Realistic experiments in bag filters 447
6.2.6 Other large-scale experiments relevant to industrial practice 451
6.3 Vent sizing procedures for the present and near future 452
6.3.1 Basic approach and limitations 452
6.3.2 Large empty enclosures of LID < 4 453
6.3.3 Large, slender enclosures (Silos) of LID > 4 453
6.3.4 Smaller, slender enclosures of L/D > 4 453
6.3.5 Intermediate (10-25 m3)enclosures of small LID 454
6.3.6 Cyclones 454
6.3.7 Bag filters 454
6.3.8 Mills 455
6.3.9 Elongated enclosures of very large LID 455
6.3.10 Scaling of vent areas to other enclosure volumes and shapes
and to other Predand dusts 455
6.3.11 Concluding remarks 456
6.4 Influence of actual turbulence intensity of the burning dust cloud
on the maximum pressure in a vented dust explosion 457
6.5 Theories of dust explosion venting 458
6.5.1 Introductory outline 458
6.5.2 Theory by Maisey 460
6.5.3 Theory by Heinrich and Kowall 460
6.5.4 Theory by Rust 462
6.5.5 Theory by Nomura and Tanaka 462
6.5.6 Theoretical analysis by Nagy and Verakis 463
6.5.7 Theory by Gruber et al. 463
6.5.8 Theory by Swift 464
6.5.9 Theory by Ural 464
6.5.10 Concluding remarks 465
6.6 Probabilistic nature of the practical vent sizing problem 465
6.6.1 Basic philosophy 465
6.6.2 The “worst credible explosion” 468

7 Assessment of Ignitability, Explosibility, and Related Properties
of Dusts by Laboratory-Scale Tests 473
7.1 Historical background 473
7.2 A philosophy of testing the ignitability and explosibility of dusts:
the relationship between test results and the real industrial hazard 475
7.3 Sampling of dusts for testing 477
7.4 Measurement of physical characteristics of dusts related to their
ignitability and explosibility 479
7.4.1 Particle size distribution and specific surface area 479
7.4.2 Dispersibility 480
7.4.3 Powder mechanical properties 485
7.4.4 Moisture content 485
7.4.5 Electrical resistivity 487