A study on combustion behaviour and reaction kinetics mechanism of some Egean region Turkish lignites

The presented paper is focused on the analysis of combustion behaviour and solid-state kinetic data of oxidation reactions of Soma-Manisa and Gediz-Kütahya lignite. Oxidation process was carried out with NI-TGA and tube furnace. The samples are heated up at temperature range from 25 to 1100 °C under multiple constant heating rates 10 °C/min, 15 °C/min, 20 °C/min and 30 °C/min in nitrogen atmosphere. Combustion characterizations of coal samples are studied by X-ray diffraction (XRD) and Fourier transform infrared spectroscopy (FTIR). Kinetic data analysis is based on model-free approaches by Kissinger-Akashiro-Sunose (KAS) and Ozawa-Flynn-Wall (OFW) with the helping of data during experimental study. The estimated kinetic constants are compared with experimental results. Oxidation parameters such as weight loss rate, burn-out temperature and reactivity of coal samples are calculated. Maximum weight loss rates are estimated at 0.54%/min Soma-Manisa lignite and 0.51%/min and Gediz-Kütahya lignite at 30 °C/min heating rate. Activation energies of coal samples are exhibited in the range 37.6—63.7 kJ/mol and 41.5–74.5 kJ/mol using OFW and KAS methods, respectively.