An Experimental Investigation on the Ignition Sensitivity and Flame Propagation Behavior of Mixed Oil Shale–Coal Dust

Abstract

ABSTRACT To evaluate the ignition sensitivity of mixed oil shale–coal dust, understand the flame propagation behavior of these mixtures during combustion and provide further reliable parameters for preventing explosion or combustion accidents associated with oil shale and coal dust, the ignition sensitivity of the mixed oil shale and two kinds of coal dust samples is examined for different mixing ratios,, using a dust layer minimum temperature test apparatus, a Godbert–Greenwold furnace, and a vertical glass tube; the flame propagation behavior of the mixed dust is observed in a vertical combustion tube and their flame propagation process is recorded with a high-speed video camera. The results show that the ignition sensitivity increases with increasing oil shale content for the mixed dust of oil shale and coal #1. . Under the same experimental conditions, both the flame front position and propagation velocity increase with oil shale content. However, for the mixed dust of oil shale and coal #2, the minimum ignition temperature of mixed dust, the minimum ignition energy of dust cloud did not change significantly with the change of oil shale, and the maximum flame front position did not differ greatly. The distribution of functional group in the mixed oil shale and two kinds of coal dust is tested using Fourier transform infrared spectroscopy (FT-IR). The result indicates that before combustion, the content of the -CH2- and -CH3 groups in the mixed dust of oil shale and coal#1 gradually increases with increasing oil shale content while the content of the -CH2- and -CH3 groups is relatively high in the mixed dust of oil shale and coal #2; aliphatic -CH3/-CH2 and oxygen-containing functional groups are key determinants for dust combustion intensity.