生活垃圾焚烧炉湿法洗涤后烟气二噁英的排放特征

PCDD/Fs EMISSION CHARACTERISTICS FROM DOMESTIC WASTE INCINERATORS FLUE GAS WITH A WET SCRUBBING

现场采样分析了4个生活垃圾焚烧炉烟气通过湿法洗涤后二噁英的排放浓度。结果表明:4个焚烧炉烟气和底灰中二噁英毒性当量浓度分别为1.15~24.88 ng I-TEQ/m^3 和25.69~231.43 ng I-TEQ/kg,烟气中二噁英排放浓度远高于国家排放标准(0.1 ng I-TEQ/m^3)(GB 18485—2014《生活垃圾焚烧污染控制标准》)。烟气同系物分析表明,湿法洗涤后4个采样点烟气中4~8氯代PCDFs分布呈现较大的差异,但是4~8氯代PCDDs 基本随氯取代数的增加而增加;底灰中4个采样点 4~8氯代PCDFs和PCDDs分布相似,除了O 8CDF外,其余同系物基本随氯取代数的增加而增加。从毒性当量浓度来看,烟气和底灰中Pe 5CDF浓度占比最大,占总浓度的35.65%~47.02%。湿法洗涤对4~8氯代PCDFs和PCDDs的效率基本随氯取代数的增加而降低,主要原因可能是高温烟气使洗涤系统内二噁英发生了解析作用。

Four simple incinerators disposing domestic waste with wet scrubbing as the flue gas purification system were surveyed by field sampling,to study the emission of PCDD/Fs.The results showed that the I-TEQ levels of PCDD/Fs in flue gas and slag were 1.15~24.88 ng I-TEQ/m^3 and 25.69~231.43 ng I-TEQ/kg,respectively.And that in the flue gas was much higher than the limit value of standard(less than 0.1 ng I-TEQ/m^3) set by China(GB 18485-2014 Standard for Pollution Control on the Municipal Solid Waste Incineration).After wet scrubbing,the distribution characteristics of the 4~8 chlorinated PCDFs homologues in flue gas from four incinerators showed great differences.But for the 4~8 chlorinated PCDDs,the contents were gradually increased with their chlorination degree.In the slag,the distributions of 4~8 chlorinated PCDFs and PCDDs homologues from four incinerators were similar.And the contents of PCDFs and PCDDs,except O 8CDF,were gradually increased with the degree of chlorination.In items of I-TEQ of PCDD/Fs homologues,the contents of Pe 5CDF in the flue gas and slag were the highest,and the percentage contents range were 35.65%~47.02%.The removal efficiency of 4~8 chlorinated PCDFs and PCDDs in the flue gas by wet scrubbing decreased with their chlorine atoms number.Analysis showed that the reason might be that the high temperature flue gas resulted in desorption of PCDD/Fs in the wet scrubbing system.