Interpretation of combustion properties of raw-pyrolyzed lignite with kinetic data

Abstract

ABSTRACT This study investigated the pyrolysis properties and kinetic behavior of Ermenek (Konya, Turkey) lignite. For this purpose, lignite was carbonized at 500°C and different heating rates (5, 10, 15, and 20°C/min). Proximate, elemental, XRF, and TGA-DTA lignite and chars were performed. Thermal analyses were performed at a heating rate of 10°C/min from room temperature to 1000°C and an inert (N2) gas flow of 50 ml/min. Peak temperatures and mass losses were determined from the data obtained from the experiments. By examining the thermogram curves, three different temperature regions depended on moisture loss, the release of volatile matter, and fixed carbon combustion. In addition, from these data, kinetic calculations were performed using Arrhenius and Coats-Redfern approaches, and the apparent activation energies were calculated for each region. The activation energy values calculated according to the Coats-Redfern kinetic model are significantly lower than those calculated according to the Arrhenius kinetic model. The highest activation energies calculated were: for Region 1 and Region 2 at 5°C/min heating rate and for Region 3 at 10°C/min heating rate.