Pyrolysis and combustion behavior of few high-ash Indian coals

Abstract

In this study, three high-ash Indian sub-bituminous coals of different thermal maturities from three different open cast mines of Raniganj basin, eastern India, were studied to understand their combustion and pyrolysis behavior. The combustion analyses were performed under three different heating rates (5°C, 10°C, and 15°C/min). From the thermograms of TG-DTG pyrolysis curves, it was observed that the overall pyrolysis reaction can be deduced into four different temperature regions with each region showing unique properties, and those regions are inherent moisture loss, prior to primary pyrolysis, primary pyrolysis, and secondary pyrolysis regions. The main pyrolysis reaction occurs in the primary pyrolysis region for all the samples but a significant devolatilization has also been seen for the early oil window mature noncoking coal in the secondary pyrolysis region. The kinetic parameters were also evaluated for both combustion and pyrolysis analysis. X-ray diffraction revealed that this sample consists of a significant amount of siderite and pyrite, and consequently showed distinct behavior. It was observed that the pyrolysis properties and kinetics were closely related to their complex mechanisms and reactions. Rock-Eval pyrolysis also confirmed the presence of siderite in the sample, which decomposed simultaneously with the organic-matter during pyrolysis.