Prediction of reduction products in the preheating process

Abstract

Under the current requirements of environmental protection, carbon peaking and carbon neutrality goals, the capacity of the new energy interconnection network is increasing day by day. The thermal power unit requires the ability of rapid load adjustment to meet the requirements of real-time power balance. However, when the unit is in a variable load condition, the denitrification system is inefficient or even inoperable. The NOx emission is large, which makes it difficult to meet environmental protection requirements. In this study, a new method for predicting reductive products in the preheating process is proposed, introducing the gasification mechanism into the pulverized coal preheating process. The effects of air coefficient on combustion temperature, velocity, O2, CO2, CO, CH4, and H2, volatile matter and NOx emission are investigated by numerical simulation. It is demonstrated that the gasification mechanism is applicable to predict the reduction products and NOx during preheating. Internal combustion burners can stabilize the precipitation of volatile matter, CH4, CO, and H2. The burner outlet temperature and flow rate decrease with decreasing air coefficient. The local maximum concentration of volatile matter and CH4 are 8.3 vol.% and 2.54 vol.%, respectively. The CO concentration increases with decreasing air coefficient under the effect of CO2 gasification reaction. When the air coefficient is 0.33, the NOx concentration at the burner outlet is 2.8 mg/Nm3 (at 6% O2).