Study of combustion characteristics of coals by thermogravimetric analysis and IR-spectroscopy

The features of the chemical composition of coals from the Tuva deposits have been determined and the corresponding possibilities of their energy-technological processing have been established. By IR spectroscopy methods it was established that in the samples of coals Zh1, Zh2, GZh the amount of aromatic carbon (aromaticity index AR 1) is the highest, which affects the flammability. GZh and G2 coals have a high index of condensation (fc). Caking of coal samples in the series Zh1-GZh-Zh2-D-B naturally decreases. Coals from the Tuvinian deposits of Mezhegeyskoye and Kaa-Khemskoye deposits have greater caking capacity. In the samples of coals Zh2, B, D “shoulders” in the region of ≈ 1730 cm-1, which are typical for the C=O valence oscillations, which indicates some natural oxidation of these coals and a decrease in their energy value, are observed. The oxidation of coals breaks down the aromatic structures with the formation of low molecular weight hydrocarbons, which, in turn, reduces the temperature of maximum decomposition of coal and the lower heat of combustion, but increases the ignitability temperature of fuel due to oxygen-containing compounds. Thermogravimetric analysis and differential scanning calorimetry showed that the Tuvinian coal sample of GZh has a high activity in the combustion process (reduction of the final burning temperature and a fairly narrow temperature range of combustion). The coals Ж1, Ж2 are less reactive.The results of studies of coal samples of different stages of metamorphism indicate that there is a possibility to control the technological process of pyrolysis or gasification of such coals, taking into account the characteristics of these coals. Also, the chemical composition and structure of Tuvinian coals should be taken into account when burning them by layer method in small volume furnaces. The obtained results can be used when designing the equipment for energy-technological processing of Tuvinian coals.