流化床O_2/CO_2燃烧(Ⅳ)-氧浓度对NO_x和N_2O的影响

O_2/CO_2 Combustion in a Fluidized Bed(Ⅳ)-Influence of the Oxygen Concentration on NO_x and N_2O

循环流化床能实现高氧气浓度下的O2/CO2燃烧,进而减少燃烧室尺寸并降低再循环烟气量。本研究使用两种烟煤、一种褐煤,分别在15 kW循环流化床试验系统和0.15MW循环流化床试验系统上进行试验,研究了氧气浓度对NOx和N2O的影响。结果表明,3个煤种均在一次风氧气浓度44.3%～55.3%、二次风氧气浓度43.2%～60.2%下实现稳定燃烧。氧气浓度约50%燃烧时,煤中氮向NOx的转化率降低到空气气氛燃烧的19%～60%,煤中氮向N2O的转化率降低到空气气氛燃烧的20%～81%。

A circulating fluidized bed can realize O2/CO2 combustion at a high oxygen concentration,thus reducing the size of the combustion chamber and the recycling flue gas quantity.The authors have tested two bituminous coal ranks and a lignite coal in a 15 kW circulating fluidized bed test system and a 0.15 kW one respectively.The influence of the oxygen concentration on the NOx and N2O was studied.The research results show that all the three coal ranks can realize stable combustion when the oxygen concentration of the primary air ranges from 44.3% to 55.3% and that of the secondary air is between 43.2% and 60.2%.When the oxygen concentration is about 50%,the conversion rate of nitrogen in the coal to NOx will decrease to 19%-60% of the nitrogen in the coal while the conversion rate of nitrogen in the coal to N2O will decrease to 20%-81% of the nitrogen in the coal when burning in the air atmosphere.