原煤与煤焦热解气化过程氮转化特性研究

STUDY ON CONVERSION CHARACTERISTICS OF NITROGEN DURING PYROLYSIS AND GASIFICATION WITH RAW-COAL AND CHAR

采用热重红外联用的方法,在线检测实验煤种在常压热重分析仪上气化时气体产物的释放过程。实验主要考察无烟煤的挥发分的析出、孔隙比表面积和孔容积对N析出与转化的影响,从反应机理上分析含N热解气化产物的转化规律。研究发现挥发分的析出速度对煤焦气化影响很明显,在原煤慢焦气化过程中,由于挥发分析出速度慢,形成的孔隙和孔容积较小,而且挥发分中含N量减少会导致焦炭N含量增加,从而使得NH_3和NO的析出量增大。在快焦气化过程中,挥发分快速析出,形成的孔隙比表面积和孔容积都较大,导致活性H较快释放生成,所以仍然有一定浓度的HCN和NH_3。

The release process of main gas products is detected on-line using TG-FTIR when the experimental coal is gasified at 25 ℃/min. The effect of the volatile releasing, pore specific surface area and pore volume of anthracite to nitrogen releasing and conversion is inspected in the experiments, and the conversion law of N-containing compounds is analyzed during coal pyrolysis and gasification from the reaction mechanism. It is found that the effect of releasing rate of volatile on coal char gasification is remarkable. During the gasification with slow-pyrolysis semi-cokes, the slow releasing rate of volatile led to less pores, and the decrease of Nitrogen content in volatile caused the increase of char-N, which are the reasons of increase of formation quantity of NH3 and NO. During the gasification of rapid-pyrolysis semi-cokes, the volatile releases very rapidly, so the pore specific surface area and pore volume became larger than that when the active hydrogen is generated rapidly, thus there is still certain concentration of HCN and NH3.