Detailed analysis of early-stage NO formation in turbulent pulverized coal combustion with fuel-bound nitrogen
Detailed analysis of early-stage NO formation in turbulent pulverized coal combustion with fuel-bound nitrogen
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DOI：
10.1016/j.proci.2020.06.317
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发表时间：
2020-09
期刊：
影响因子：
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通讯作者：
X. Wen;A. Shamooni;O. Stein;L. Cai;A. Kronenburg;H. Pitsch;A. Kempf;C. Hasse
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文献类型：
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作者：
X. Wen;A. Shamooni;O. Stein;L. Cai;A. Kronenburg;H. Pitsch;A. Kempf;C. Hasse
对混合层内煤粉燃烧进行了载相直接数值模拟，考虑了燃料NOx、热NOx和瞬时NOx三种NOx生成机理。进行了详细的分析，包括反应路径分析、化学时间尺度分析、优先顺序和预算分析，以研究NOx的产生机理和火焰面模型的性能。考虑到CP-DNS的计算成本较高，本文的工作主要集中在脱挥发分控制的早期阶段，其中焦炭反应不是很重要。反应路径分析表明，燃料型氮气煤粉火焰中主要的热-NO反应贡献了NO的净消耗量，这与无燃料型氮气火焰有本质的区别。化学时间尺度分析表明，NOx的生成速率快于主要物种的生成速率，证实了火焰表的适用性。优先分析表明，火焰模型可以很好地预测气体温度和主要/中间组分，而NOx组分在某些地区表现出明显的差异。最后，预算分析解释了为什么火焰面模型对主要/中间和NOx物种的表现不同。
A carrier-phase direct numerical simulation (CP-DNS) of pulverized coal combustion in a mixing layer is performed, considering three NOxformation mechanisms (fuel-NOx, thermal-NOxand prompt-NOx). Detailed analyses, including reaction path analysis, chemical timescale analysis, anda prioriandbudget analysesare conducted to investigate the NOxproduction mechanisms and the performance of the flamelet model. Considering the high computational cost of CP-DNS, this work focuses on the early phase governed by devolatilization, where char reactions are less important. The reaction path analyses show that the principal thermal-NO reaction contributes to the net consumption of NO in fuel-bound nitrogen pulverized coal flames, which is essentially different from fuel-nitrogen-free flames. The chemical timescale analyses show that the production rates of NOxspecies are faster than those of major species, which confirms the suitability of the flamelet tables. Thea priorianalyses show that the gas temperature and major/intermediate species can be predicted well by the flamelet model, while the NOxspecies show significant discrepancies in certain regions. Finally, thebudget analysesexplain why the flamelet model performs differently for major/intermediate and NOxspecies.