Evaluation on oxy-fuel co-combustion behavior of Chinese lignite and eucalyptus bark

The combustion behaviors of lignite/eucalyptus bark under oxy-fuel condition were assessed based on a thermal analysis technique. The influences of oxygen concentration, heating rates and blending ratios on oxy-fuel combustion performances were revealed, which were compared with those in air. The ignition and comprehensive combustion indices increased with increasing oxygen contents during oxy-fuel combustion. At three heating rates of 10, 15 and 20 K min(-1), the average comprehensive performance indices of lignite/eucalyptus bark in 40 %O-2/60 %CO2 were about 5-7 times more than those in air. The average comprehensive performance indices of lignite/eucalyptus bark in air were about 2-3 times more than those in O-2/CO2 atmosphere at analogous oxygen content. At heating rate of 20 K min(-1), the ignition and comprehensive performance indices of lignite/eucalyptus bark in 25 %O-2/75 %CO2 were very near to those in air. The combustion kinetics were also evaluated in conjunction with volatile matter and fixed carbon burning periods using Doyle's and Coats-Redfern's models. The oxy-fuel combustion kinetics of lignite/eucalyptus bark at oxygen content of 30 % was similar to that in air. There were more significant synergistic effects between lignite and eucalyptus bark during their co-combustion in air and O-2/CO2 with oxygen contents of 25 and 30 %.