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 nitrogen oxide
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, 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 (@6% O2).