Influence of CO₂ Effect on Coal Char Combustion in Oxygen-enriched Environment

An analysis was conducted to the influence of O₂ concentration, CO₂ chemical effect and thermal effect on the coal char combustion rate in oxygen-enriched environment containing a certain amount of CO₂ with Ar gas to control the surface temperature of the coal char particles, based on a continuous-film model considering the coal char surface C-O₂/C-CO₂ reactions and the gas phase CO-O₂ reaction. Results show that when the volumetric fraction of O₂ rises from 21% to 26.5% in the oxygen-enriched environment, the surface temperature of char particles would be increased by 154 K, resulting in increased burning rate, and shortened ignition and burnout time. O₂ concentration plays the most important role in influencing the coal char combustion rate, followed by CO₂ chemical effect, and then by thermal effect, with relative contributions of 56.4%, 25.7% and 17.9%, respectively.