Oxy-fuel co-combustion performances and kinetics of bituminous coal and ultra-low volatile carbon-based fuels

The co-firing of bituminous coal under oxy-fuel conditions is a feasible measure to improve the ignition and combustion performances of ultra-low volatile carbon-based fuels and effectively control pollutants. The present study aimed at the co-combustion performances and kinetics of bituminous coal and ultra-low volatile carbon-based fuels under oxy-fuel condition by means of thermogravimetric experiments. The results indicate that the volatile content in fuels is likely to affect the ignition temperature and the oxy-fuel co-firing of bituminous coal accelerates the ignition and advances combustion of ultra-low volatile fuels. The combustion behaviors of individual fuel are retained in the co-firing process to a large extent, and there is a slight synergy at the 350 to 950 degrees C temperature range. Enhancing the oxygen concentration is effective to improve the combustion performances of ultra-low volatile fuels in oxy-fuel atmosphere. The apparent activation energy of residual carbon from coal-water-slurry gasification in oxy-fuel atmosphere exceeds that from fluidized bed gasification, which is highly related to gasification technology and raw fuel properties. The apparent activation energy under condition of co-firing bituminous coal and residual carbon from coal-water-slurry varies considerably, changed from 100 to 46 kJ/mol. Therefore, the addition of bituminous coal significantly reduces the activation energy of ultra-low volatile fuels to improve the co-firing performances. Based on the present investigation, a better understanding on the oxy-fuel co-firing of various carbon-based solid fuels is obtained, thereby promoting the efficient and clean utilization of solid waste in the coal chemical industry.