With the continuous development of pulverized coal preheating combustion technology

char-N occupies a dominant position in the formation of nitrogen oxides. In order to study the NO emission and combustion characteristics of thermal char(different from room-temperature char) in the preheating combustion mode

a twostage drop-tube furnace was built

and the effects of pyrolysis temperature

combustion temperature and excess air ratio on NO emission and combustion characteristics of the boiler were experimentally investigated. The results show that

increasing the pyrolysis temperature of pulverized coal is beneficial to reduce NO emissions for thermal char which is different from the experimental results of room-temperature char. When the excess air ratio α=1.0

the maximum NO emission reduction efficiency is 21.1%. The influence of combustion temperature on NO emissions strongly depends on the excess air ratio in the combustion zone. The NO emission decreases with the increasing combustion temperature on NO emission when strong reducing atmosphere appears in the furnace

and the law is reversed when the oxidation atmosphere appears in the furnace. Increasing the preheating temperature and the combustion temperature are beneficial to reduce the carbon content in fly ash. When α=1.0

the maximum decrease of carbon content in fly ash is 28.6%.