Characteristics of NO/SO 2 generation during coal/steel dust co-firing under multi-factor synergies

The co-combustion of solid waste and coal in industrial kilns represents the primary method for the treatment of solid waste. This process must address the critical issue of efficiently controlling nitrogen oxides (NO) and sulfur dioxide (SO2) emissions. In this study, we initially conducted combustion experiments using both single-fuel and mixed-fuel configurations involving coal and steel dust. The experimental results indicated a positive correlation between temperature, airflow rate, and NO/SO2 emissions, while the mixing ratios exhibited a negative correlation. A straightforward regression prediction model for NO/SO2 emissions was developed to enhance understanding of the generation characteristics of NO and SO2, notably, the relative deviation from experimental results was merely 3.16%. This model integrates fuel properties with combustion conditions to elucidate the emission characteristics of nitrogen oxides (NO) and sulfur dioxide (SO2) at their source. Finally, Response surface methodology (RSM) was applied to analyze NO/SO2 emissions under varying operating conditions, including temperature (700–900 °C), air flow rate (80–200 mL/min), and mixing ratios (10–50%).The optimal results were observed at a blending ratio of 50%, where nitrogen (N) and sulfur (S) conversion rates decreased by 25% and 23%, respectively. The results of the analyses determined that the key factors affecting NO emissions, in order of influence, are the mixing ratio, temperature, and air flow rate. For SO2 emissions, the order is mixing ratio, air flow rate, and temperature.