无烟煤燃烧中的重金属排放及分布特性

Emissions and Distribution Characteristics of Heavy Metals in the Combustion of Anthracite Coal

为得到无烟煤燃烧中的重金属排放及分布特性,采用3.5 MW燃烧实验台进行中试实验,对无烟煤燃烧过程中的Pb、Cd、Cu、Zn、Ni和Cr等6种重金属的排放及分布特性进行了测试。实验结果表明：6种元素在飞灰中的质量分数均高于底渣,且富集于超细颗粒中,富集程度的顺序为：Pb,Cd〉Cu,Zn〉Ni,Cr。其中,Pb和Cd在粒径约为1μm的飞灰中富集因子达到17-22。在燃烧产物中,重金属大部分分布在飞灰中,底渣和烟气中的比例很低。其中,Cd、Cu、Ni等元素全部分布在飞灰和底渣中,而Pb、Zn和Cr则少量分布在烟气中,以气态形式存在,Pb的质量分数最高、达到13.4%。

In order to obtain the emissions and distribution characteristics of heavy metals in the combustion of anthracite coal, a pilot experiment was performed on a 3.5 MW combustion test rig and the emissions and distribution characteristics of Pb, Cd, Cu, Zn, Ni and Cr totaling six kinds of heavy metal were tested during the combustion of anthracite coal. The test results show that the concentrations of six kinds of element in the flying ashes will be all higher than that of the slags at the bottom and rich in superfine particles with the sequence of the enrichment extents being as follows： Pb, Cd 〉 cU, Zn 〉 Ni, Cr, among which Pb and Cd will have an enrichment factor of 17 to 22 in the flying ashes with a particle diameter of around 1 p.m. In the combustion products, a majority of heavy metals will be distributed in the flying ashes and slags at the bottom while a minority of Pb, Zn and Cr will be distributed in the flue gases, existing in the form of gas state and the mass ratio of Pb will be the highest,reaching 13.4%.