在基于循环流化床预热的无烟煤粉燃烧实验台上,在循环流化床空气当量比低于0.3的条件下对无烟煤粉在预热过程中煤氮的迁移和转化特性进行了研究.结果表明,煤氮的主要转化产物为NH3和N2;随着煤中挥发分含量的升高和煤阶的降低,煤氮的转化率和煤氮向N2的转化率增加;随着预热温度的升高,煤氮的转化率和煤氮向N2的转化率增加,预热生成的NH3质量浓度降低;随着循环流化床空气当量比的增加,煤氮的转化率和煤氮向N2的转化率增加,预热生成的NH3的质量浓度降低.煤氮向NH3和N2的转化反应以及NH3和N2之间的转换反应是决定无烟煤预热过程中煤氮迁移转化的主要热化学反应.
Experimental studies were carried out on a test rig of pulverized anthracite coal combustion preheated by a circulating fluidized bed(CFB). The anthracite was preheated in the CFB with excess air ratio less than 0.3,and coal nitrogen transformation characteristics during the preheating process were investigated. It is found that coal nitrogen mainly transforms into NH3 and N2. The coal nitrogen conversion rate and the conversion rate of coal nitrogen into N2 increase with the increase in volatile content and decrease in coal rank. With the increase in preheating temperature and excess air ratio in the CFB,the concentration of NH3 generated during preheating process decreases while the coal nitrogen conversion rate and the conversion rate of coal nitrogen into N2 increase. The transformation of coal nitrogen into NH3 and N2,and the conversion reaction between NH3 and N2 are the main thermal-chemical reactions which determine the transformation of coal nitrogen during anthracite preheating process.