不同煤化程度煤的热解及氮的释放行为

Release behavior of nitrogen in different rank coals during pyrolysis

采用热重-红外-质谱联用技术（TG-IR-MS）,对4种不同煤化程度的煤进行热解实验,实时记录了煤在30~1 100℃,以10℃/min升温速率、氦气气氛下热解过程中的质量变化和生成气体成分。研究结果表明：随着热解温度的升高,煤中逐渐释放出氮化物,如HCN,NH3等。不同煤化程度的煤具有不同的N释放行为。气煤、焦煤、1/3焦煤等主要以NH3与HCN两种形式释放,无烟煤热解时主要是以NH3形式释放。煤热解释放的HCN和NH3来源于不同的氮。HCN可能主要来源于煤分子边缘的五元环吡咯氮和六元环吡啶氮,而NH3主要来源于煤分子内部的季氮。NH3的释放经历了2个阶段：低温（550℃）阶段为煤中挥发分的初级热解产物;高温（750~850℃）阶段为煤中挥发分的二次热解产物。

The combined thermo gravimetric-infrared-mass spectrometry （TG-IR-MS） analysis were conducted under the temperature of 30 ℃ to 1 100 ℃ with a heating rate of 10 ℃/min to monitor the different rank coal＇ s pyrolysis and nitrogen release behavior online. The thermal analysis results show that the various nitrides like HCN and NH3 are released from coals during pyrolyzing. The released products vary with different coalification coals during pyrolysis. Ni- trogen is mainly released in the forms of NH3 and HCN in gas coal, 1/3 coking coal and coking coal, but NH3 in the high rank coal. The HCN and NH3 come from different types of nitrogen in the coal＇ s internal structure. The HCN may be mainly derived from the edge of five-membered rings pyrrole nitrogen and six-membered rings pyridine nitrogen in coals, the NH3 from the inside quartery nitrogen. The release of NH3 experience two stages ： the lower temperature stage at which it is from the elementary pyrolysis of volatile components;and the high temperature stage at which it is from the secondary pyrolysis of volatile components.