Conversions of fuel-N, volatile-N, and char-N to NO and N2O during combustion of a single coal particle in O2/N2 and O2/H2O at low temperature

Oxy-steam combustion is a promising next-generation combustion technology.Conversions of fuel-N,volatile-N,and char-N to NO and NO during combustion of a single coal particle in O/Nand O/HO were studied in a tube reactor at low temperature.In O/N,NO reaches the maximum value in the devolatilization stage and NO reaches the maximum value in the char combustion stage.In O/HO,both NO and NO reach the maximum values in the char combustion stage.The total conversion ratios of fuel-N to NO and NO in O/Nare obviously higher than those in O/HO,due to the reduction of HO on NO and NO.Temperature changes the trade-off between NO and NO.In O/Nand O/HO,the conversion ratios of fuel-N,volatile-N,and char-N to NO increase with increasing temperature,and those to NO show the opposite trends.The conversion ratios of fuel-N,volatile-N,and char-N to NO reach the maximum values at b ON=30 vol%in O/N.In O/HO,the conversion ratios of fuel-N and char-N to NO reach the maximum values at b ON=30 vol%,and the conversion ratio of volatile-N to NO shows a slightly increasing trend with increasing oxygen concentration.The conversion ratios of fuel-N,volatile-N,and char-N to NO decrease with increasing oxygen concentration in both atmospheres.A higher coal rank has higher conversion ratios of fuel-N to NO and NO.Anthracite coal exhibits the highest conversion ratios of fuel-N,volatile-N,and char-N to NO and NO in both atmospheres.This work is to develop efficient ways to understand and control NO and NO emissions for a clean and sustainable atmosphere.