To study the relationships between coal quality

coal combustion characteristics(thermal analysis)

furnace temperature and NOx emission

low NOx combustion experiment in a 600 MW supercritical boiler was conducted

firing four single coals and four blending coal mixtures

with constant operation parameters.The results show that:the NOx concentration gradually dropped with the increasing fuel ratio

and changed smoothly once the fuel ratio exceeded 0.48;the content of N in coal had no significant effect on the NOx emission;the NOx emission changed little with the coal ignition temperature but increased with the raising burnout temperature;moreover

the furnace temperature at upper region of the main burner also increased with the raising burnout temperature

indicating the flame center moved up;due to the weakening reducing atmosphere

reducing air staging depth and increasing furnace temperature at reducing region

the NOx emission showed a dramatic growth tendency.