Oxy-fuel co-combustion properties and N-containing pollutants release characteristics of biomass/coal blends

Thermal properties and NO release characteristics during oxy-fuel co-combustion of pine sawdust (PS) and Shenmu coal (SM) were investigated based on the effects of various parameters, including atmosphere, temperature, blending ratio, and oxygen concentration in this research. The results indicate that the release of NO decreased with the increasing temperature during decomposition process of PS and SM. The content of N-Q and N-X in semicoke (SC) increased at higher torrefaction temperature. The N-Q and N-X content for SC at the temperature of 1000 °C was 36.9 % and 23.2 %, respectively. When 40 % PS was added to the SM, the NO release amount was significantly reduced by 16.3–23.1 % in the oxy-fuel atmosphere compared to the O₂/N₂ atmosphere, and the ignition time was reduced from 4.0s to 0.66s. The NO emission initially increased and then decreased as the combustion temperature increased from 800 to 1000 °C. Furthermore, increasing the oxygen concentration from 10 % to 40 % shortens the combustion time and increases the emissions of NO. Conversely, increasing PS blending ratios from 10 % to 40 % decreased NO emission and the conversion ratio. These findings emphasize that adding biomass can effectively improve coal ignition, increase combustion rates, reduce NO emissions, and address the air pollution problems associated with NOx emissions.