Air and oxy-fuel combustion characteristics of coal gangue and weathered coal blends

Oxy-fuel combustion technology is suggested as one of the promising technologies for capturing CO2. The combustion characteristics of blends of a coal gangue and a weathered coal under air (21% O2/79% N2), oxy-fuel (20% O2/80% CO2) and oxygen-enriched oxy-fuel (40% O2/60% CO2) conditions were studied using a ther-mogravimetric analysis (TGA) technique operating at heating rate 10 oCmin  1 to a final temperature 900 degrees C, focussing on the effect of blending ratio and atmosphere. While the differential thermogravimetric (DTG) profiles of coal gangue in the three different atmospheres were very similar, the weathered coal showed a sharp peak in the temperature range 400-440 degrees C under oxygen-enriched oxy-fuel condition, which was different from DTG curves under air and oxy-fuel conditions. The blending of the coal gangue into the weathered coal gradually diminished this peak. The negligible deviations between the experimental DTG curves and theoretical DTG curves indicated that interactions were absent for all the coal gangue/weathered coal mixtures under air and oxy-fuel conditions. The obvious interactions between coal gangue and weathered coal were observed under oxygen-enriched oxy-fuel condition and the interaction may be related to thermal effect. The interactions increased as the increasing weathered coal ratio in blends and increasing oxygen concentration under oxy-fuel conditions.