Local ignition process

Lugovskoi et al. (28) in a qualitative study experimentally observed the ignition process on suspended catalyst particles (H2 + 02) and showed the relations between the local values of the transport coefficients and spots where the ignition process starts. 

Such hot spots react instantaneously as localized, constant volume sub-explosions (Urtiew and Oppenheim 1966 Lee and Moen 1980). If the mixture around such a sub-explosion is preconditioned sufficiently to ignite on shock compression, a detonation wave will engulf the entire process of flame propagation. 

In a thermite process to produce chromium metal, the mechanically-mixed ingredients were ignited in a large crucible and the reaction proceeded smoothly. When the mixer broke down, manual mixing was used but gave poorer dispersion of the constituents. An explosion after ignition is attributed to a high local concentration of sodium chlorate and aluminium powder in the mixture. 

Plant layout is a crucial factor in the safety of a process plant because of e.g. segregation of different risks, containment of accidents and limitation of exposure. Safe plant layout is designed on the basis of design standards and local regulations. These are often expressed as minimum clearances between equipment. Safety distances between plant items can in principle be calculated by estimating the size of possible leaks, the probability of ignition and explosion... 

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