Abstract
In this paper, one studied the effect of pulsed laser radiation (1064 nm, 120 μs) on lignite. The method of mass spectrometry was used to analyze the formed gaseous reaction products after the exposing of coal samples to the laser radiation. The pressed out of the pre-milled coal particles tablets were used as samples. In the mass spectra of the reaction products of laser radiation of the samples, the peaks with a mass to ion charge ratio m/z = 2, 18, 44 were detected, that corresponds to the main peaks of H2, H2O, and CO2 molecules. The pattern of formation of the end products CO2, H2, H2O when heating a sample of coal by laser radiation is proposed. The energy release factor is calculated, which is defined as the ratio of the calorific value, released during combustion of the sample to the dose of energy absorbed by the sample during irradiation.
Highlights
The coal particles ignition is a combination of physicochemical processes occurring simultaneously, viz. moisture evaporation, heat transfer and mass transfer, thermal decomposition of coal particles, chemical interaction of pyrolysis products with water vapor, oxidation of gaseous combustible components on the coal particles surface, etc. [1].The laser radiation is one of the promising tools for initiating the coal particles’ ignition process [2,3,4,5,6]
The technique of measuring the background mass spectrum is as follows: the sample was placed in an experimental chamber, the experimental chamber was sealed, the mass spectrum of gaseous materials was recorded in the chamber without any exposure to laser radiation
The mechanism of oxidation reactions of coal material under laser radiation exposure is definitely more complex process than we describe through reactions 3‒7
Summary
The coal particles ignition is a combination of physicochemical processes occurring simultaneously, viz. moisture evaporation, heat transfer and mass transfer, thermal decomposition of coal particles, chemical interaction of pyrolysis products with water vapor, oxidation of gaseous combustible components on the coal particles surface, etc. [1]. The complexity of studying the mechanism of this process is due to the high rates of chemical reactions occurring simultaneously in the solid and gaseous phase and the interfacial space, as in the case of high-energy materials combustion [7]. The first stage manifests itself (appears) during the laser pulse duration of 120 μs with a threshold energy density. [12,13,14,15,16] show that the process of ignition and combustion of a coal particle has three stages: the heating of a coal particle as a result of the influence of laser radiation and the subsequent development of the thermochemical reactions in a sample, the emission and ignition of the volatiles, the combustion of the coke residue of a coal particle. The ionization of gases in the analyzer is carried out using an electron impact
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