不同煤种对烟气中汞的形态和分布的影响

Effects of different kinds of coal on the morphology and distribution of mercury in flue gases

采用化学热平衡分析方法研究了不同煤种燃烧过程中汞元素的化学形态及其分布.选用的煤种为唐山烟煤、高平无烟煤、贵州六盘水贫煤、小龙潭褐煤、印尼褐煤及宜昌褐煤6个煤样,在50~700℃温度范围内,比较讨论了不同煤样在氧化性气氛中汞的化学形态和物理相.结果表明:烟气温度较低时,原煤中S元素含量对烟气中汞的形态和分布的影响占主导地位;而原煤中Cl-含量越多,低温时最容易实现从HgSO4到HgCl2的转化,高温时最难实现从HgCl2到单质Hg的转化;相对于其它煤种,S和Cl元素在褐煤燃烧过程中的这种影响相对弱些.

The chemical morphology and distribution of Hg during different coal combustion processes are examined based on the chemical thermal equilibrium analysis. The selected raw coals include Tangshan bituminous coal,Gaoping anthracite coal,Liupanshui lean coal,Xiaolongtan lignite coal,Indonesia lignite coal,and Yichang lignite coal. The chemical morphology and physical phase of Hg are compared under the oxidizing atmosphere in a temperature range of 50 ~ 700 ℃. The results show that the speciation and distribution of Hg are closely related to coal type and the content of S in coal when temperature is low. The higher content of Cl in coal is,the longer the existence interval of HgCl2in flue gas will be. It is easier to transform HgSO4to HgCl2in low temperature but it is more difficult to transform HgCl2to Hg in high temperature. The morphology and distribution of mercury are clearly influenced by S and Cl elements in the flue gas of coal combustion process,which is relatively weak for lignite coal.