低NO_(x)燃烧过程中H_(2)S生成的化学反应动力学分析

Chemical Reaction Kinetic Analysis of H_(2)S Generation in Low NOx Combustion

针对低NO_(x)燃烧技术在燃煤锅炉应用中容易促进硫化氢的产生,进而加剧高温腐蚀的现象,采用化学动力学分析方法对H_(2)S详细反应机理进行分析,研究不同气氛和温度条件下,含硫气相物质的主要反应路径及其生成速率.结果表明:基元反应H_(2)S+H=SH+H_(2)在反应初期对H_(2)S的分解过程起主要作用,自由基SH与H2S发生快速转化.同时NO也会对H_(2)S生成起到抑制作用,主要是基元反应SH+NO=SN+OH与SN+NO=N_(2)+SO产生的氧化性物质所导致.在过量空气系数α≤1时,H2S体积分数随着温度的增加而减少.沿反应器轴向,H2S体积分数先减小后增加,随着温度的降低反应器出口H2S体积分数大幅增加,在1400℃、1300℃、1200℃、1100℃时,体积分数分别增加约15.93×10^(-6)、57.90×10^(-6)、173.20×10^(-6)、328×10^(-6).

The application of low NO_(x)combustion technology in coal-fired boiler tends to promote the generation of hydrogen sulfide,which further exacerbates the phenomenon of high-temperature corrosion.The chemical kinetic analysis method was used to analyze the detailed reaction mechanism of H_(2)S,and the main reaction paths and formation rates of sulfur-containing gas phase substances were studied under different atmosphere and tempera-ture conditions.The results show that the elementary reaction H_(2)S+H=SH+H_(2)plays a major role in the decomposition of H2S at the initial stage of the reaction,and the radicals SH and H_(2)S are rapidly transformed.At the same time,NO also inhibits the generation of H_(2)S,which is mainly caused by the oxidizing substance generated by the elementary reactions of SH+NO=SN+OH and SN+NO=N_(2)+SO.At an excess air coefficientα≤1,the H2S concentration decreased with increasing temperature.Along the reactor axis,the H2S concentration first decreased and then increased.With the decrease of temperature,the H2S concentration at the reactor outlet increased significantly.At 1400℃,1300℃,1200℃,and 1100℃,the concentration increased by about 15.93×10^(-6),57.90×10^(-6),173.20×10^(-6),328×10^(-6),respectively.