Conversion of volatile-nitrogen and char-nitrogen to NO during combustion
Conversion of volatile-nitrogen and char-nitrogen to NO during combustion
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DOI：
10.1016/s0016-2361(02)00175-8
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发表时间：
2002-12
期刊：
影响因子：
7.4
通讯作者：
Suparin Chaiklangmuang;Jenny M. Jones;M. Pourkashanian;A. Williams
中科院分区：
文献类型：
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作者：
Suparin Chaiklangmuang;Jenny M. Jones;M. Pourkashanian;A. Williams
采用分级燃烧或分层燃烧等低NOx策略的低排放燃烧室的设计需要对燃料挥发分和焦炭燃烧的燃烧过程有详细的了解。本文讨论了煤燃烧的几个方面-挥发分和煤焦。挥发性燃烧，即预混和扩散燃烧的极端情况下进行检查，以考虑燃烧室设计师提供的NOx还原选项的范围。一组类似的情况下检查焦炭燃烧和释放的燃料氮形成NO。被认为是在两个实际应用中的过程的影响，高温燃烧中发现的粉煤燃烧和流化床燃烧的条件下，在较低的温度制度。在粉煤火焰的情况下，挥发物的混合程度在确定NO形成的程度中起主导作用，而炭-氮的作用仅是形成NO，并且由于反应区末端的短停留时间和低炭浓度，NO还原受到限制。在循环流化床燃烧器中，得出的结论是，可能出现不同的情况。如果床足够大以提供几秒的停留时间，则流化床中最初形成的NO在稳态条件下被床顶部和提升管中的碳还原，并且其在出口处的浓度可以通过平衡计算来估计。
The design of low emission combustion chambers using low NOxstrategies involving staged burning or stratified combustion requires a detailed understanding of the combustion processes of the fuel volatiles and char burning. In this paper some aspects of the combustion of coal-volatiles and char are considered. The extreme cases of volatile combustion, namely premixed and diffusive burning are examined in order to consider the range of NOxreduction options available to the combustion chamber designer. A similar set of situations is examined for char burning and the release of the fuel-nitrogen to form NO. The implications of the processes are considered in two practical applications, those of the high temperature combustion found in pulverised coal burning and in a lower temperature regime of the conditions under fluidised bed combustion. In the case of pulverised coal flame the degree of mixedness of the volatiles played a dominant part in determining the extent of NO formation whilst the role of char-nitrogen is only to form NO and NO reduction is limited because of the short residence time and low char concentrations at the end of the reaction zone. In a circulating fluidised bed combustor it was concluded that a different situation can arise. If the bed is sufficiently large enough to give a residence time of several seconds, then the NO initially formed in the fluidised bed is reduced by the carbon in the top of the bed and the riser under steady state conditions and its concentration at the exit can be estimated by equilibrium calculations.