Ignition of mixtures of coal dust, methane, and air by hot laminar nitrogen jets
J. M. Singer
1963
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Key Takeaway Key Takeaway: Ignition suppressors can reduce the ignition hazard of detonation products from explosives by reducing the ignition temperatures and concentrations of coal dust, methane, and air in hybrid mixtures.
Abstract
Ignition temperatures and limiting fuel concentrations of mixtures of coal dust, methane (firedamp), and air have been determined by the hot-gas jet ignition method. Ignition promoters and ignition suppressors were also incorporated into the hybrid mixtures and into the hot jet. This study was limited to use of a single coal having about 37 per cent volatile matter, ground to about 1–5 microns. Hybrid mixtures containing coal dust and air in approximately stoichiometric balance for complete combustion required minimal methane concentrations for ignition at given temperatures. Ignition temperatures and concentrations were decreased by addition of 90 per cent CO+10 per cent H 2 to the hot jet. Ignition was inhibited when gaseous halogenated hydrocarbons were added to the hot jet or to the hybrid mixture. The inhibiting action of the additives investigated decreased in the following order: bromotrifluoromethane, methyl bromide, carbon dioxide, and water vapor. Our observations suggest that ignition suppressors adsorbed on inert dusts, incorporated into water-stemming cartridges, or into the explosive charge itself, will reduce the ignition hazard of detonation products from explosives.