An investigation into a carbon burnout kinetic model for oxy-coal combustion

This paper investigates coal char burnout kinetics in the oxygen-enriched environments of oxy-coal combustion. The Carbon Burnout Kinetic model (CBK) developed by Hurt et al. was used as the basic model for air-coal combustion and a modified version for oxy-coal combustion. In order to assess the performance of the original CBK model published experimental data from standard char combustion studies at near-atmosphere and elevated pressures were used. The results of the evaluation suggested that the modified model can be utilized for oxy-coal applications. The modifications include the integration of Langmuir-Hinshelwood kinetic rate mechanisms for C-CO₂ and C-H₂O reactions and the effects of CO and H₂ concentration on these reactions. The modified code is validated using published experimental data. It is shown that using this modified code, the burnout prediction in both N₂ and CO₂ environments has improved significantly. Computed results of Loss on Ignition (LOI) in a 1 MW_th pilot scale combustion test facility are compared with experimental data.