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Ultraviolet, Visible, and Infrared Emission Spectra of Propagating Methane-coal-dust Inhibitor Flames.
Fink-ZJ; Dalverny-LE; Grumer-J
NTIS: PB 237 893 :56 pages
Ultraviolet-visible and infrared emission spectra from propagating methane-coal-dust inhibitor mixtures have been obtained in a 0.2- By 0.2- By 5.3-M vertical dust over a range of flame speeds from 2 to 100 m/sec. Results serve as a basis for the design and evaluation of thermal radiation detectors for triggered barriers that suppress ongoing mine explosions. Of particular significance is the large continua superimposed on the methane-air spectra when small amounts of coal dust are present and the variation of emissivity with infrared (ir) wavelength in dust flames. In conjunction with the spectral measurements, studies of flame speed, particle size, gas sampling plus thermodynamics, and dust sampling are presented and discussed to gain insight into the more fundamental aspects of propagating explosions. Sampling results have shown that only a near-stoichiometric amount of dust is consumed in the flames studied even though initial concentrations are five times stoichiometric. Difficulty in propagating coal-dust inhibitor flames of realistic mine characteristics in a cold-walled laboratory duct has been encountered. A simplified analysis of the flame zone utilizing spectral and sampling results indicates that the stability of slowly propagating flames is more dependent upon thermal radiation than upon convection losses to the walls. It is predicted that thermal radiation losses will make any measurements of coal dust burning velocities, "quenching diameters," or flammability limits more apparatus dependent than those corresponding to gaseous fuels.
IH; Report of Investigations
NTIS Accession No.
NTIS: PB 237 893
Page last reviewed: May 5, 2020
Content source: National Institute for Occupational Safety and Health Education and Information Division