Influence of Inlet Dilution of Reactants on Premixed Combustion in a Recuperative Furnace
Influence of Inlet Dilution of Reactants on Premixed Combustion in a Recuperative Furnace
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DOI：
10.1007/s10494-011-9348-x
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发表时间：
2011-04
期刊：
影响因子：
--
通讯作者：
Pengfei Li;J. Mi
中科院分区：
文献类型：
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作者：
Pengfei Li;J. Mi
本文采用RANS模型进行数值模拟，研究了外部稀释对回热炉内预混燃烧的影响。计算使用详细的GRI-Mech 3.0机制来执行，以确保建模的准确性。提供了炉内流动、温度以及OH、O2、CO2和NOx浓度的结果。研究发现，惰性气体CO_2的外部稀释对建立预混温和(中等或高度低氧稀释)燃烧具有重要作用。反应物混合物的外部稀释不仅降低了O2的初始浓度，而且通过更多热燃烧产物的再循环确保了更强的内部稀释。重要的是，后一种效应对于实现温和的制度更为重要。稀释剂CO2有一个临界质量分数，低于这个分数不能发生温和燃烧。尽管传统的预混火焰比温和燃烧产生的NOx多得多，但无论发生哪种模式，NOx的排放似乎都是由热不燃烧途径产生的最多，N2O途径产生的最少。此外，本模拟还表明，预混燃烧比扩散燃烧在更宽的初始反应物条件范围内出现温和模式。
This paper presents a numerical study by RANS modeling that investigates the effect of external dilution on the premixed combustion occurring in a recuperative furnace. Calculations are performed using the detailed GRI-Mech 3.0 mechanism to ensure the accuracy of the modeling. Results of the in-furnace flow, temperature, and concentrations of OH, O2, CO2and NOxare provided. It is found that the external dilution with the inert gas CO2plays a significant role in establishing the premixed MILD (Moderate or Intense Low-oxygen Dilution) combustion. Externally diluting the reactant mixture not only reduces the initial concentration of O2but also ensures a stronger internal dilution by recirculation of more hot combustion products. Importantly, the latter effect is more significant for achieving the MILD regime. There is a critical mass fraction of the diluent CO2present, below which MILD combustion cannot occur. While the traditional premixed flame produces much more NOxthan the MILD combustion, the emission of NOxappears to result most from the thermal-NO route and least from the N2O route no matter which mode occurs. Moreover, the present simulation demonstrates that the MILD mode occurs over a wider range of initial reactant conditions for premixed combustion than for diffusion combustion.