Study on the combustion behaviours of two high-volatile coal particle streams with high-speed OH-PLIF

•The ignition of bituminous coal and lignite is dominated by their volatiles.•The devolatilization rate of bituminous coal changes less than that of lignite.•The flame stability of the bituminous coal particle stream is much higher.•The volatile releasing ratio of bituminous coal was less than that of lignite.