珠三角地区生活垃圾焚烧厂汞的排放特征

Mercury emission characteristics from municipal solid waste incineration in Pearl River Delta region

利用OH法对珠三角8家垃圾焚烧厂(6家采用炉排炉工艺,2家采用流化床工艺)进行烟气采样,同时采集飞灰、底渣、煤炭样品进行分析.研究结果表明,珠三角炉排炉焚烧烟气平均总汞(THg)排放浓度为(51.4±28.3)μg·Nm-3,流化床为(19.5±13.6)μg·Nm-3.炉排炉飞灰THg含量为6674μg·kg-1,流化床飞灰THg含量为2135μg·kg-1,底渣中炉排炉THg含量为70μg·kg-1,流化床为30μg·kg-1.飞灰中的汞含量要远远高于底渣.垃圾焚烧过程中炉排炉70.8%的汞由烟气排放,26.3%存在飞灰中,底渣中的汞仅占2.9%.流化床工艺烟气汞排放占总汞排放的33.2%.利用质量平衡法计算珠三角垃圾中汞含量平均值为0.293 mg·kg-1,流化床工艺因添加燃煤所产生的汞排放占到垃圾焚烧总汞排放的31.6%.

Flue gas, fly ash, bottom ash, and coal samples were collected from eight municipal solid waste incineration plants in the Pearl River Delta （PRD）, six of which used grate furnace combustor （GFC） and two used circulation fluidized bed combustor （FBC）, using the Ontario Hydro （OH） method to analyze total mercury （THg）. The mean concentrations of THg in flue gas from GFC plants and FBC plants were （51.428.3） and （19.513.6） μgNm-3, respectively. Fly ash contained much higher THg （6674 μgkg-1 for GFC incinerator, and 2135 μgkg-1 for FBC incinerator, respectively） than bottom ash （70 μgkg-1 for GFC incinerator and 30 μgkg-1 for GFC incinerator, respectively）. During waste combustion for GFC, mercury can be released via flue gas, fly ash, and bottom ash with the percentages of 70.8%, 26.3%, and 2.9%, respectively. However, for FBC, mercury emission via flue gas accounted for 33.2% of the total. The average amount of mercury in municipal solid waste （MSW） in the PRD was calculated to be 0.293 mgkg-1 based on its mass balance. And the emission of mercury from FBC plants contributed 31.6% of the total due to coal added in incineration.