,
A few fundamental aspects about ignition and flame propagation in dust clouds
Journal of Loss Prevention in the Process Industries, 19 (2-3): 104--120 (2006)
DOI: http://dx.doi.org/10.1016/j.jlp.2005.06.035
Аннотация
The history of the development of the process industry has been punctuated
by a number of hazardous explosions, sometimes very severe. A few
of them are still in the memory and certainly contributed to the
birth of safety engineering. It has been known for more than one
century than combustible dusts suspended in air are responsible for
a part of those explosions but contrariwise to gas explosions, the
available knowledge and practise seems still contain a significant
part of empirism. The work summarised into this paper is an attempt
to contribute to a better understanding of the explosion mechanisms
of dust clouds. Hopefully, such additional information may help to
refine the safety analysis exercise in the future. A specific effort
has been devoted to combustion processes in the flame and the results
indicate similarities with premixed gaseous flames. Several fundamental
questions are addressed such as the incidence of thermal radiation,
turbulence,... This information is important to treat ignition aspects.
For spark type of ignition, it is shown that an absolute minimum
ignition energy should exist for some dust clouds with a similar
meaning than for premixed gaseous flames. For hot surface ignition,
the standard ignition temperature (Godbert-Greenwald) seems to be
reasonably correlated to the size and critical ignition temperature
of the heating body. The possible implications of this new information
within the scope of industrial safety are addressed in conclusion.
