Model and experimental validation on NOxemission of biomass combustion in rotary kiln with HTAC

Based on the existing forms and evolution of Fuel-N in biomass fuels during high temperature air combustion (HTAC), a model mainly considering fuel-NOxand thermal-NOxformation was established. Through numerical calculation, the NOxemission behaviors of biomass fuel, rice husk, in rotary kiln were studied. The calculated results show that NOxcontent increases with air temperature increasing, and this trend is accelerating after the air temperature 1000-1050°C, NOxcontent decreases with lowering of oxygen mole content in air. There is a remarkable drop when oxygen mole content is under the critical value, 8%, reducing of air consumption coefficient shapes the reductive atmosphere, and then inhibits NOxformation. At 1200°C, air consumption coefficient drops to 0.8 from 1.8, and NOxcontent decreases to 150 mL/m3from 400 mL/m3roughly. Comparing the data of NOxobtained from experiment with the values by numerical calculation, the results show that the rules of NOxemission appear the same trend, and the average relative error is about 7% between calculated values and experimental data. The proposed model is proved to be reliable and the NOxemission in HTAC can be lower.