甲烷、丙烷掺混对乙烯扩散火焰中碳烟生成影响

Effects of methane and propane blending on soot formation in ethylene diffusion flame

鉴于日益严格的污染物排放法规和减排需求,研究燃料掺混燃烧对碳烟排放的影响是具有价值的。采用GRI-Mech3.0气相反应机理并结合详细的热力学和输运数据,对层流扩散火焰乙烯/甲烷和乙烯/丙烷混合燃料燃烧进行了数值模拟。对比分析了各工况的燃烧温度分布、碳烟分布以及重要中间组分浓度变化。结果表明,掺混甲烷和丙烷均导致乙烯扩散火焰中峰值温度和碳烟体积分数减小,相同掺混比下掺混甲烷的碳烟体积分数减小幅度更大。随着掺混比增加,温度和碳烟体积分数峰值分布向火焰下游发展,H自由基摩尔分数逐渐减小,OH自由基摩尔分数略有减少,C2H2摩尔分数逐渐减小且分布向火焰下游移动。在该研究的扩散火焰工况下,甲烷和乙烯掺混以及丙烷和乙烯掺混在碳烟生成方面均未发现协同效应。

In view of the increasingly stringent pollutant emission regulations and emission reduction needs, it is valuable to study the effect of fuel blending combustion on soot emission.The GRI-Mech3.0 gas phase reaction mechanism combined with detailed thermodynamics and transport data was used to numerically simulate the combustion of ethylene/methane and ethylene/propane mixed fuels in a laminar diffusion flame.The combustion temperature distribution, soot distribution and concentration changes of the key intermediate species under various working conditions were compared and analyzed.The results show that the peak temperature and soot volume fraction in the ethylene diffusion flame are reduced by blending methane and propane, and the soot volume fraction of blending methane decreases even more at the same blending ratio.With the increase of blending ratio, the distributions of peak temperature and soot volume fraction develop downstream of the flame, the mole fraction of H radicals gradually decreases, the mole fraction of OH radicals decreases slightly, the mole fraction of C2H2gradually decreases and the distribution moves to the downstream of the flame. Under the diffusion flame cases studied, there is no synergistic effect in the soot formation by the mixing of methane and ethylene and the mixing of propane and ethylene.