The impact of H2O on NO emission during oxy-fuel co-combustion of coal/NH3 by experimental investigation and molecular dynamic calculation

Abstract

To reduce CO₂ emission in power station, coal and ammonia co-combustion in boilers has garnered widespread attention. In this work, NO release behaviors of coal and ammonia co-combustion at O₂/H₂O/CO₂ atmosphere with different H₂O concentration are analyzed by experiment and molecular dynamics calculation. The results reveal that NO emission increases with the ratio of blending NH₃ increasing, but it is relatively low when only ammonia is burned. As coal and ammonia are co-fired, the NO emission rises with the H₂O concentration increasing from 0 % to 30 %. Reactive force field molecular dynamic (ReaxFF MD) simulations exhibit that the increase in combustion temperature promotes the intermediates contained nitrogen to convert to NO, and the NO formation rate is accelerated. With the rise in H₂O concentration, the NO formation in the initial stage of the reaction is accelerated, mainly because the increase of the H₂O concentration greatly accelerates the OH formation.