Investigation of combustion kinetics of Umutbaca-lignite by thermal analysis technique

In this study, TG/DSC analysis was used to obtain the information on the combustion behavior, profile, and thermal kinetics of Umutbaca (Turkey) lignite. The thermal analysis data were obtained from 298 to 1273 K at 1, 2.5, 5, and 7.5 K min(-1) heating rates in air atmosphere at TG-DSC apparatus. It was seen that when the heating rates increased, the ignition temperature and the burn-out temperature increased. The kinetic parameters were also determined by using two model-free methods [Flynn-Wall-Ozawa (FWO) and Kissinger-Akahira-Sunose (KAS)] and with model-fitting (Coats-Redfern). The activation energies (E (a)) calculated for KAS and FWO were 118 and 129 kJ mol(-1), respectively. ln(A) was 18.09. It was found that diffusion mechanism [D-4: (1 - 2 alpha/3) - (1 - alpha)(2/3)] depicts the combustion process of Umutbaca-lignite by using Coats-Redfern method.