Study On The Nox Emission And The Conversion Path Of Fuel Nitrogen Of O₂/N₂ And O₂/CO₂ Oxygen-enriched Staged

The dominant position of coal in Chinese energy consumption structure will not change in the medium and long term.Energy conservation and improving energy efficiency are one of the main ways to achieve the carbon peaking and carbon neutrality goal.It is particularly important to develop efficient and clean pulverized coal combustion technology.Based on the experimental platform of the two-stage drop tube furnace,this paper study the temperature of the main combustion zone（1300℃～1500℃）,the excess oxygen coefficient of the secondary air（0.3～1.04）and secondary air oxygen concentration（15%～100%）on the combustion efficiency and NO_xemission,and analyzed the release law of each component and the migration and transformation law of nitrogen in coal in the process of pulverized coal combustion.The experimental results show that the temperature of the main combustion zone,the excess oxygen coefficient of the secondary air and the oxygen concentration of the secondary air all have interactive effects on the NO_xemission concentration.The high temperature and strong reducing atmosphere in the main combustion zone is the key to achieve ultra-low NO_xemissions.In the strong reducing atmosphere,NO emission concentration and fly ash carbon content are lower in O₂/CO₂,and increasing oxygen concentration can achieve ultra-low NO_xemission,whenα₂=0.3 and c₂=30%～60%,NO emission concentration can reach ultra-low emission requirement.The release rate of each component in the coal during the combustion of pulverized coal in the main combustion zone increased with the increase of the excess oxygen factor of the secondary air,and the release rate of each component in the coal was relatively higher in the O₂/CO₂enriched oxygen atmosphere.Under the deep classification condition,the N released from coal was mainly converted to N₂,and a small amount was converted to HCN and NH₃,and NO_xwas not detected in the flue gas.with the increase of the secondary air excess oxygen coefficient,the conversion rate of HCN and NH₃decreased,and NO_xemission was gradually measured,which indicated that under the deep air classification condition,the NO_xformed by the initial oxidation of pulverized coal combustion was fully reduced to N₂.