掺烧高硫煤对某600MW机组锅炉的影响及运行优化

Influence of co-firing high suffur coals on operation of a 600MW unit boiler and the operation optimization

电站锅炉掺烧高硫煤会给锅炉运行带来不利影响。本文通过数值模拟研究了掺烧高硫煤前后炉内贴壁腐蚀性气氛、煤粉燃尽率、污染物排放等参数的变化,并对掺烧高硫煤后烟气酸露点的变化进行了计算。结果表明:掺烧高硫煤后,炉内贴壁H2S体积分数明显上升,高温腐蚀风险加大,同时煤粉燃尽率降低,烟气酸露点提高;在下层燃烧器层掺烧高硫煤,高金属壁温区域高H2S体积分数区域面积占比较小,约为35%,较常规运行工况炉膛出口CO体积分数上升约0.35%,固体可燃物质量浓度上升约0.4 g/m^3,其效果较中、上层燃烧器层掺烧更具优势。

Co-firing high suffur coals has adverse effects on boilers’operation.Numerical simulations are conducted to study the combustion characteristics before and after co-firing high suffur coals,such as the corrosive gas near the water wall,the burnout rate and pollutant emission.Moreover,the acid dew point is calculated after co-firing high suffur coals.The results show that,the volume fraction of H2S near the water wall rises and the risk of high-temperature corrosion increases after co-firing high suffur coals.Meanwhile,the burnout rate reduces and the acid dew point increases.When co-firing high suffur coals in lower burners,the area containing high volume fraction of H2S is lower,about 35%.Compared with the conventional operating conditions,the volume fraction of CO rises by about 0.35%and the mass fraction of solid combustibles rises by about 0.4 g/m^3.The effects of co-firing high suffur coals in lower burners are better than in intermediate and upper burners.