Staged combustion and oxy-fuel combustion are both effective technologies to control NOx emission for power plant. Besides, blending fuel is also widely used in power plants. In this paper, CHEMKIN software was used to simulate the NOx formation characteristics. The co-combustion simulation of semi-coke and bituminous coal in this paper was under oxy-fuel atmosphere and deep oxygen-staging conditions. All of these combustion conditions were considered to explore the rule and reaction path of NOx formation. The simulation results show that when the temperature of the main combustion zone is below 1400 oC, the conversion of NO to N2 is promoted, while the condition is opposite at temperature above 1400 oC. Accelerating the NH2 transforming to NH rather than HNO can promote the fuel-nitrogen transforming to N2, reducing the generation of NO. This study can provide new insight into NOx formation and reaction mechanism of boiler deep oxygen-staging oxy-fuel co-combustion.
Keywords deep oxygen-staging combustion, NOx, blending combustion, oxy-fuel combustion