Variations in combustion properties of coal with average relative density and functional groups identified by FTIR analysis

This work presents experimental results of combustion characteristics of low volatile Indian coal. Coal of different average relative density (ARD) varying from 1.35 to 2.0 was generated by density fractionation of the coal. Coal samples were characterized by proximate analysis, Fourier-transform infrared spectroscopy (FTIR), ultimate analysis, and gross calorific value (GCV). Combustion experiments were conducted to identify the effects of ARD and functional groups on combustion characteristics. It was observed that with the rise in ARD of coal from 1.45 to 2.0, the ignition temperature increased from 357°C to 417°C. Highest coal combustion rate was observed for 1.525 ARD coal, due to the presence of all types of hydrocarbons, alcoholic, aldehyde, and trisubstituted alkene (except primary amines) as seen from FTIR analysis. Analyses of coal combustion rate and GCV indicate that 1.45 ARD coal has the highest GCV, heat release rate, and lowest ash generation rate, properties that are best suitable for thermal utilities.