微米铝粉在氢气/水蒸气氛围下燃烧机制研究

Study on combustion mechanism of micron-sized aluminum powder in hydrogen/water vapor atmosphere

为探究铝制品在生产加工过程中蕴含的气粉两相体系爆炸风险,揭示铝粉在潮湿环境下燃烧机制,基于Chemkin软件模拟微米铝粉在氢气/水蒸气氛围下微观反应进程,结合铝粉气相燃烧机制,构建包含Al、O、AlO、AlO_(2)、AlH等28组分、68步基元反应的化学反应动力学模型。通过改变水蒸气与空气的摩尔比,分析水蒸气含量对燃烧温度敏感性的影响,以及对关键自由基的摩尔分数和最大生成速率的影响。结果表明:基于温度敏感性分析,发现水蒸气含量的增加会降低微米铝粉平衡时的燃烧温度。其中,影响平衡时燃烧温度的关键基元反应R32(即Al+H_(2)O=AlOH+H),由开始的先促进升温后抑制升温变为完全抑制升温。基于生成速率分析,得出水蒸气含量的增加会降低O和AlO自由基平衡时的摩尔分数。基于反应路径分析获取微米铝粉在氢气/水蒸气氛围下燃烧的关键反应路径,其中,Al→O、Al→AlO、Al_(2)O_(2)→AlO等基元反应较强。

In order to study the explosion risk of the gas-powder two-phase system contained in the production and processing of aluminum products,the combustion mechanism of aluminum powder in humid environments was revealed.The microscopic reaction process of micron-sized aluminum powder in a hydrogen/water vapor atmosphere was simulated based on Chemkin software.According to the gas phase combustion mechanism of aluminum powder,a kinetic model of a chemical reaction containing 28 components(Al,O,AlO,AlO_(2),AlH,etc.,)and 68-step elementary reactions was constructed.By varying the mole ratio of water vapor to air,the effects of water vapor content on the sensitivity of combustion temperature,as well as the mole fraction and maximum rate of production of key free radicals were analyzed.The results show that according to the temperature sensitivity analysis,the increase in water vapor content will reduce the combustion temperature of micron-sized aluminum powder when reaching equilibrium.Specifically,the key elementary reaction R32(Al+H_(2)O=AlOH+H),which affects the combustion temperature at equilibrium,changes from promoting the temperature rise at the beginning and then suppressing the temperature rise to completely suppressing the temperature rise.According to the analysis of the rate of production,the increase in water vapor content reduces the mole fraction of O and AlO free radicals when reaching equilibrium.According to the reaction path analysis,the key reaction path of micron-sized aluminum powder during combustion in a hydrogen/water vapor atmosphere is obtained,among which Al→O,Al→AlO,Al_(2)O_(2)→AlO,and other elementary reactions are strong.