负荷和煤种对燃煤机组烟气汞迁移的影响研究

Research on Affect of Load and Coal on Migration of Hg in Fuel Gas of Coal-fired Generating Unit

为研究燃煤机组烟气中汞(Hg)的迁移特性,同时采用安大略法和活性炭吸附管法,对不同负荷、不同煤种工况下某典型燃煤机组中烟气Hg的迁移排放规律进行了全过程研究,并对各输入、输出物料进行了系统的Hg质量平衡核算,在此基础上得到Hg的迁移规律,明确了负荷和煤种因素对烟气Hg排放的影响。结果表明,各研究工况下烟气Hg的排放浓度均显著低于新国标规定的排放限值,系统总的脱Hg效率达90%以上;试验机组配套电袋复合除尘器,对气态Hg吸附和细小飞灰颗粒捕集的效果较好,有利于Hg的脱除;与高负荷相比,低负荷下Hg的排放浓度更低,其主要原因在于较低的烟气温度更有利于Hg2+在除尘环节的吸附脱除;对于研究中的两个煤种,虽然高Hg煤对应的氯含量和Hg去除率较高,但由于其总Hg含量相对高得多,最终Hg排放浓度仍然更高。

In onder to stuthy the migration of Hg in fuel gas of Ocoal-frreel generating unit,by means of Ontario hydro method and activated carbon absorption method,this paper studies migration and emission principles of Hg in fuel gas of some typical coal-fired generating unit under different working conditions including different loads and coals types.Mean-while,systematic Hg quality balance check on various input and output materials were conducted.Migration principle of Hg was obtained and affects of loads and coal types on Hg emission in fuel gas were clarified.The results indicate that emission concentration of Hg in fuel gas under different working conditions is obviously lower than emission limit values provided by national standards and the total Hg removal efficiency is over 90%.Meanwhile,effect of absorbing gaseous Hg and gather-ing tiny fly ash particles by mating electrostatic fabric filter for the test unit is good for removing Hg.Comparing with high load working condition,emission concentration of Hg under low load working condition is lower due to lower gas tempera-ture being more favorable to absorb and remove Hg2＋ in process of dedusting.For the two coal types in research,chlorine content of the high Hg coal and Hg removal efficiency is higher,but for reason of relatively high total content of Hg,emis-sion concentration of Hg is still higher.