煤及其模型化合物快速热解过程中HCN和NH_3逸出规律的研究

Formation of HCN and NH_3 during the Rapid Pyrolysis of Coal and Model Compounds

利用高频热解装置对褐煤、烟煤和无烟煤三种不同煤阶的煤及模型化合物吡咯、吡啶进行了热解实验,分别考察了煤热解终温为1200℃,平均升温速率为2.7,8.0,11.9,17.1,22.9℃·s-1和不同热解终温(600～1200℃)下煤及吡咯、吡啶快速热解过程中HCN和NH3的生成规律,并且对煤热解过程中HCN和NH3逸出的影响因素进行了分析。结果表明:褐煤、烟煤的HCN转化率随升温速率增加而降低,无烟煤的HCN转化率随升温速率增加先增加后基本保持不变;褐煤、烟煤的NH3转化率随升温速率增加而增加,无烟煤的NH3转化率随升温速率增加降低。褐煤和烟煤的HCN转化率随温度升高而降低,无烟煤的HCN转化率随温度升高而增加;褐煤、烟煤、无烟煤的NH3转化率随温度升高均先增加后降低;在不同升温速率热解条件下总氮的转化率:褐煤>烟煤>无烟煤,在不同温度下快速热解时总氮的转化率:烟煤>褐煤>无烟煤。模型化合物吡咯快速热解时,NH3为主要的含氮产物,吡啶快速热解时,HCN为主要的含氮产物。

The rules and the influencing factors of HCN and NH3 formation during the pyrolyses of lignite,bituminous,anthracite,pyrrole and pyridine at different heating rates and different temperatures in a high frequency furnace were investigated.The experiments were conducted with target temperature of 1200℃ and average heating rates of 2.7,8.0,11.9,17.1 and 22.9℃ s 1,respectively,for pyrolyses of above coals,and with rapid heating to different reaction temperatures of 600~1200℃ for pyrolyses of above coals and model compounds of pyrrole and pyridine.The results indicate that the yields of HCN during pyrolyses lignite and bituminous decrease with increasing heat rate or temperature,while the HCN yield of anthracite pyrolysis increases with the increase of temperature and it also increases with the increase of heating rate at first and then turns to be constant with the further increase of heating rate.With increasing the heating rate,the NH3 yields of lignite and bituminous pyrolyses increase,while NH3 yield of anthracite pyrolysis decrease.With the increase of the temperature,the NH3 yields of pyrolyses of all above coals increase and then decrease.The sequence of total-N yields during pyrolyses of different coals at different temperature is as follows： lignite bituminous anthracite,and the sequence of total-N yields during pyrolyses of different coals at different temperatures is following： bituminous lignite anthracite.It was also found that the NH3 is the main nitrogen-containing product during the pyrolysis of pyrrole,while HCN is the main nitrogen-product during the pyrolysis of pyridine.