煤炭解耦燃烧过程N迁移与转化Ⅰ:热解阶段煤N的释放规律

Nitrogen transformation during coal decoulping combustion I:release behavior of coal-nitrogen during pyrolysis stage

在固定床装置上进行了三种煤的热解实验,考察了热解温度、热解时间等因素对煤氮迁移转化的影响。热解实验表明,A煤1 073 K热解产生HCN,在热解前3 min释放完毕,早于NH3释放,且当NH3开始逸出后HCN生成量急剧减少;三种煤热解HCN、NH3的累积释放量在不同时刻达到各自最大值后急剧下降;半焦氮随热解温度的升高而增加。在973～1 123 K三种煤热解有50%～60%煤氮转化为焦氮,40%～50%煤氮随挥发分一起释放,挥发分氮有20%～50%的氮物种以NH3和HCN的形式存在,其中,HCN占气相氮的50%～60%、NH3占40%～50%。

Effect of temperature and residence time on coal-nitrogen transformation during pyrolysis of 3 coals from west China was studied in a fixed bed reactor.The results show that the duration time of HCN releasing is about 3 min at 1 073 K for pyrolysis of coal A.The start release time of HCN is earlier than that of NH3,and the released amount of HCN quickly drops to zero as NH3 starts to release.The accumulated release amounts of HCN and NH3 first reach the maximum value at different pyrolysis time and then decrease sharply.The yield of char-nitrogen increases with increasing temperature.At 973～1 123 K,about 50～60 mass percentage of the coal-nitrogen exits in char as char-nitrogen and the rest is released as volatiles,in which about 20～50 mass percentage of the volatile-nitrogen is NH3 and HCN.The mass percentage of NH3 accounts for 40%～50% and that of HCN about 50%～60% in the volatile-nitrogen.