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Radiant Heating of Coal Dust Clouds by Flames in Coal Mine Galleries.
NTIS: PB 196 687 :15 pages
Approximate equations were used to compute the radiant heating of float coal dust by approaching flames for various combinations of particle size, dust path length (flame travel distance), flame temperature, dust concentration, flame speed, and flame length. The computed values of degree of radiant heating and flame travel distance for preheating the coal dust should be useful for estimating the increased fire hazard of different coal dust-flame parameters. Some findings relating to coal mine disaster control are--(1) coal dust clouds cannot be preheated to ignition temperatures by flame radiation alone when deflagration speeds are greater than about 10 m/sec. Thus it appears unlikely that radiation alone will cause flames propagating in dust clouds to accelerate to detonation velocities. (2) Small particles in the radiation flame zone caused by burnout and soot formation increase the degree or preheat significantly. (3) The concentration of float coal dust (radii = 3 to 40 microns) for maximum radiant heating usually peaks in the range 50 to 200 mg/liter of air.
IH; Report of Investigations
NTIS Accession No.
NTIS: PB 196 687
Page last reviewed: March 11, 2019
Content source: National Institute for Occupational Safety and Health Education and Information Division