Study of the kinetic dependences of the glow and determination of the threshold characteristics of ignition of coals with different stages of metamorphism under the action of microsecond laser pulses

Abstract

In this work, the study of the kinetic dependences of the glow and determination of the threshold characteristics of the ignition of coal of grades long-flame, semi-lean caking, weakly caking, lean and anthracite under the action of microsecond laser pulses was carried out. For the aforementioned coals, three successive stages of ignition were found with characteristic Hcr thresholds. The first stage of ignition is associated with the heating of the surface of coal particles and the ignition of microprotrusions; the duration of the glow practically repeats the duration of the laser pulse. The second stage of ignition is associated with the release and ignition of volatiles in a millisecond time interval; the third-with the ignition of a non-volatile residue, the glow duration reaches 120 ms. With an increase in the degree of coalification, almost constant values of the first ignition threshold Hcr(1) are found. For the studied coals, with an increase in the degree of coalification, a decrease in the second threshold Hcr<2) and an increase in the third ignition threshold Hcr (3)are observed.