Thermogravimetric Analysis of the Combustion Characteristics and Combustion Kinetics of Coals Subjected to Different Chemical Demineralization Processes

Abstract

In order to explore the influence of different chemical demineralizations on coal combustion characteristics and combustion kinetics, five coals subjected to different chemical demineralization processes were investigated via thermogravimetric analysis. The ash contents of clean coal was reduced to 0.1-1.55% after different chemical demineralizations. The ignition temperature of coal decreased by 12-69 °C, and the peak temperature decreased by 7-62 °C. The burnout temperature of clean coal increased by 63 °C after demineralization by NaOH. The adsorption of noncombustible NaOH into the porous structure of TaiXi-3 caused an increase in burnout temperature. Alkali-soluble minerals were proven to have a negative effect on the combustion performance of coal, while acid-soluble minerals had the opposite effect. The combustion kinetics of five kinds of coals at a heating rate of 10 °C/min was investigated. The activation energy of coal obviously changes before and after demineralization (58.39-91.39 kJ mol-1). The activation energy of clean coal is obviously lower than that of raw coal.