Effects of flue gases (CO/CO2/SO2/H2O/O2) on NO-Char interaction at high temperatures

The effects of major flue gases (CO/CO2/SO2/H2O/O-2) on the NO-char interaction at realistic high temperatures in the reburning zone of boiler are investigated, through the HEFR and HDTF at 1200-1500 degrees C. The results indicates that CO could significantly promote the NO-char interaction, with its temperature-sensitive region at 3%-5% CO center dot CO2 (<5%) would promote NO reduction rate by 5-16%, while CO2 in larger concentration has little effect on NO-char interaction. The effect of SO2 on the NO-char interaction is limited. H2O from 0 to 20% would make an increase of NO reduction rate by approximately 18%, with the formation of CO and HCN. 0.8% is the optimal O-2 concentration promoting the NO-char reduction. Even with a small amount of oxygen (0.8% O-2), the addition of H2O could promote NO reduction at 1200 degrees C. With O-2 from 0.8% to 4% with 10% H2O, the temperature-depending effects of H2O and O-2 on NO-char interaction is advanced from 1.0 s to 0.5 s, even earlier. With CO2 from 5% to 11% with 0.8% O-2, the temperature-depending effects of CO2 and O-2 on NO-char interaction could be advanced from 1.5 s to 0.5 s. (C) 2019 Elsevier Ltd. All rights reserved.