再燃过程再燃煤粉燃料N释放规律的试验研究

EXPERIMENTAL INVESTIGATION ON FUEL-N RELEASE CHARACTERISTIC OF REBURN FUEL

再燃煤粉燃料N的释放特性是影响再燃过程中NO还原效率的关键因素。在携带炉煤粉再燃试验过程中采集了不同实验条件下经历不同反应时间的煤焦样,对其元素构成进行了测定,并分析了不同煤粉细度、再燃燃料比和再燃区氧量下再燃煤粉燃料N的释放规律,研究了燃料N释放与NO还原效率间的关系,并对N、H、O等元素的释放速率进行了比较。结果表明,在不同实验条件下,再燃煤粉燃料N的释放对NO还原效率的影响规律也不相同,减小再燃煤粉粒径可促进燃料N迅速释放,有利于提高NO还原效率;降低再燃燃料比或提高再燃区氧量也可促进燃料N迅速释放,但会导致NO还原效率下降;再燃区初始氧量小于4％时,氧量改变对燃料N的释放速率影响显著。在相同的实验条件下,燃料N的释放速率比燃料H和燃料O的释放速 率小。

For rebuning with pulverized coal, the NO reduction rate depends strongly on fuel-N release characteristic of reburn coal. Experiments of rebuming with pulverized coal was carried out on an entrained-flow reactor, and the element compositions of chars collected under different coal particle sizes, reburn fractions, rebum zone oxygen contents were analyzed . The release characteristic of fuel-N and the relationship between fuel-N release and the NO reduction rate have been investigated. The comparison of release rates of fuel-N, fuel-H and fuel-O has been made. Experimental and analysis results indicate that decreased coal particle size may prompt the release of flue-N and increase the NO reduction rate; Decreased reburn fuel fraction and increased rebum zone oxygen content may also lead to increased fuel-N release rate while may cause decreased NO reduction rate. The fuel-N release rate is sensitive to reburn zone oxygen content when the initial reburn zone oxygen content is less than 4%. The fuel-N presents lower release rate compared with fuel-H and fuel-O.