Kinetics of pressurized oxy-combustion of coal chars

Publication date: Available online 28 September 2019Source: Thermochimica ActaAuthor(s): Piotr Babiński, Grzegorz Łabojko, Michalina Kotyczka-Morańska, Marek ŚciążkoAbstractA kinetic study of oxy-combustion of chars received from two Polish coals, namely lignite and hard subbituminous was conducted. The kinetics of char oxy-combustion was examined in the TA Instruments TG-HP150 s pressurized thermogravimetric analyzer at 0.1, 0.5 and 1 MPa of absolute pressure. The experiments were carried out at isothermal conditions and at wide range of temperature (773–1273 K). Mixture of gas containing 20% and 30% of O2 in CO2 was used as an oxidant. Additionally at temperature 873 K the experiments were performed using 5%, 10% and 40% of O2 in CO2. A kinetic model of pressurized oxy-combustion of coal char was presented. Kinetic parameters such as activation energy, pre-exponential factor and reaction order in respect of oxygen concentration were computed. Influence of temperature, pressure and O2 concentration were discussed. The results show a significant shift of the oxycombustion reaction from kinetically controlled regime to diffusion – controlled regime with increasing temperature and pressure. The method of selecting the proper reaction model was presented based on the integral and differential approach of experimental data analysis.
Source: Thermochimica Acta - Category: Chemistry Source Type: research