Intensification of the Process of Coal Ignition by Adding Biomass under Flame Combustion Conditions

Abstract

The characteristics of thermal decomposition and combustion processes on the heating of fine particles (100–200 μm) of Chernogorsky coal, larch wood, and mixtures based on them, including the concentrations of the main components of flue gases (CO, CO₂, NO_x, and H₂S + SO₂), were determined using modern techniques, analytical instrumentation, and experimental equipment. The biomass contents of the fuel mixtures based on coal were 10, 20, and 30 wt %. The temperatures at which the ignition of the coke residue occurred and the combustion process was completed were established using the thermogravimetric analysis of individual solid fuels and their mixtures. Larch sawdust was more reactive than Chernogorsky coal due to the lowest temperature at which the carbon residue was ignited; therefore, the addition of even 10% biomass to coal had a positive effect on the reactivity of the mixture. Under conditions of fuel heating in a flow of air at temperatures of 500–800°C, the ignition delay times were determined using a hardware–software complex for high-speed video recording of fast processes. Based on the results of the experimental studies, it was found that the ignition delay times of the test fuels in a flow of heated air varied in a range from 0.02 to 0.22 s, and the addition of 10–30 wt % biomass to coal shortened the ignition delay times of fuel mixtures by up to 50%. The analysis of flue gases upon the combustion of solid fuels made it possible to establish the concentrations of the main anthropogenic emissions; the use of biomass as an additive to coal reduced the emissions of carbon dioxide, nitrogen oxides, and sulfur compounds (H₂S + SO₂) by 2.2–13.5, 6.2–28.9, and 18.2–33.3%, respectively.