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Characterization on Ignition and Volatile Combustion of Dispersed Coal Particle Streams: In Situ Diagnostics and Transient Modeling

In this paper, applying OH-PLIF diagnostics, we explored the ignition and volatile combustion of dispersed coal particle streams in a Hencken flat-flame burner. The effects of ambient temperature and oxygen mole fraction on coal combustion behaviors have been systematically examined. First, different coal combustion stages and ignition modes (i.e., heterogeneous ignition, homogeneous ignition, and hetero-homogeneous joint ignition) in different ambiences are characterized by the OH profiles within the coal flame domain, with ignition delay time and volatile combustion time being quantitatively determined. Then, an improved transient model, integrating the gas-phase flame-sheet reaction model and the chemical percolation devolatilization (CPD) model, is established to reveal the underlying physicochemical mechanisms during the early stage of coal combustion. This transient model well captures the effects of ambiences on both the characteristic ignition delay time and volatile combustion time. Finally, base...