煤粉预热–燃烧耦合过程中NO生成研究

Study on NO Formation During Preheating-combustion Coupling of Pulverized Coal

为探究煤粉预热-燃烧耦合过程中NO生成规律,借助2个串联的高温管式炉详细研究预热区温度、停留时间及空气当量比对NO生成影响,并借助Chemkin Pro利用反应动力学进行NO生成模拟与生成率(rate of production,ROP)机理分析。实验结果表明:预热温度升高,预热停留时间延长,均降低NO生成;随预热区空气当量比增加,NO生成量先减小后增加,最佳空气当量比约为0.4。煤粉预热-燃烧过程中NH2、CH3、HCCO、NCO和HCO为主要的NO还原基团,且CHi对NO的还原作用显著强于含氮化合物。此外,预热区O活性基团的存在是NO还原的关键。

In order to investigate NO formation during the preheating-combustion process of pulverized coal,two high-temperature drop tube furnaces were connected in series to study the effect of preheating temperature,residence time and air equivalence ratio on NO formation.Meanwhile,The NO generation simulation and ROP(rate of production)analysis during preheating-combustion process were performed by means of Chemkin Pro.The experimental results show that the NO yields reduces under both higher preheating temperature and longer preheating residence time.With the increase of the air equivalence ratio in the preheating zone,the NO yields decreases first and then increases,and the optimal pre-combustion zone air equivalence ratio is obtained around 0.4.Reaction kinetic simulation analysis reveals that NH2,CH3,HCCO,NCO and HCO are the main NO reduction chemical groups in the preheating-combustion process of pulverized coal,but the reduction of NO by hydrocarbons is significantly stronger than that of nitrogen-containing compounds.Meanwhile,the presence of O radical is an important factor in NO reduction.