Abstract:
The results of measurements of the spectral-kinetic characteristics of the glow of the flame of eight brands of stone coals of the Kuznetsk coal basin (Russia) among metamorphism and anthracite are presented during and after exposure to the impulses of the neodymium laser (1064 nm, 120 $\mu$s). At the first stage, at the values of the critical density of the laser energy of $H_{\mathrm{cr}}^{(1)}$, the reactive-active micro-extracts on the surface of coal particles are ignited. It was shown that at the second stage, when the critical energy density $H_{\mathrm{cr}}^{(2)}$ is reached, during the radiation impulse, the surface of the coal particles and a flame of 3–4 mm with a height of 3–4 mm occurs. The shape of the flame glow spectra is associated with the contribution of several components: burning carbon particles, excited molecules H$_2$O$^*$, H$_2^*$ and CO$^*$. It is most likely that this stage is associated with thermochemical reactions in the aliphatic part of the coal macromolecule. In the third stage, with an increase in the density of laser energy to the $H_{\mathrm{cr}}^{(3)}$ flame, the height of the flame reaches 3–4 cm. At distances of more than 4 mm from the surface in the spectra of the glow, one component is observed in the time interval of more than 1 ms, the spectrum of which is described by the formula of the bar. It is assumed that the processes in coal particles occurring in the third stage are associated with the ignition of the aromatic part of the coal macromolecules.
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