Sn/O/H/N/C/Cl系统中锡的氧化动力学研究

控制燃煤锅炉中Sn的排放已经越来越被环境学界所关注。已有数据表明气相排放的和残留在飞灰中的Sn的变化范围很大,引起这种变化的原因还不清楚。在尾部烟道附近,Sn以元素态和二价氧化物蒸汽形式存在,已知水溶性二价锡氧化物更容易从烟气中脱除。为了更好地控制Sn的排放,必须了解燃烧过程中Sn的反应产物以及各浓度与时间的关系,即Sn的反应动力学机制,该文首次采用量子化学经典过渡态理论的方法研究了烟气中痕量元素锡的关键基元反应动力学参数,继而提出了Sn/O/H/N/C/Cl系统的氧化动力学模型。在典型的反应温度和组分浓度下进行了动力学的数值模拟,并通过敏感性分析找到了影响系统反应速率最重要的基元反应。

The Oxidation Kinetics of Tin in Sn/O/H/N/C/Cl System

The potential for regulation of tin emissions from coal-fired boilers is a concern for the electric utility industry. Field data show a wide variation in the fraction of tin that is emitted as a vapor vs. that retained in the solid products. The reason for this variation is not well understood. Near the end of the flue gas path, tin exists as a combination of elemental vapor and SnO vapor. The data show that soluble SnO is more likely to be removed from the flue gas. So the chemical kinetic mechanisms of tin are needed to describe accurately tin reaction products and their concentrations-time correlation. It is necessary to develop tin chemical kinetics for application to real combustion system. Based on quantum chemistry theory and transition state theory, reaction mechanism of tin during coal combustion was studied. The paper presented a complex model of tin oxidation in Sn/O/H/N/C/Cl system. The most important chain branching steps in this oxidation process were obtained through the sensitivity analysis.