水泥窑PM_(2.5)排放特性及其PAHs风险分析

Characteristics of PM_(2.5) emitted from cement kiln and the risk assessment of PAHs in PM_(2.5)

采用荷电低压颗粒物撞击器(ELPI)、便携式PM2.5采样器和稀释系统,对国内3家新型干法水泥生产厂(5条生产线)的水泥窑(包括窑头和窑尾)进行现场采样,分析水泥窑排放PM2.5的质量浓度、粒数浓度及其中的多环芳烃(PAHs)浓度,对呼吸致癌风险进行评价.结果表明:从粒数浓度分析,PM2.5中70%以上为PM0.33,这部分颗粒物主要是由气化凝结形成的.各采样点排放的PAHs主要以二环和三环的低环PAHs为主.第3个水泥厂窑头排放的PAHs含量最高,而且苯并[a]芘(BaP)超过国家所规定的8ng/m3标准限值,同时其呼吸致癌风险水平为4.46×10-4,高于可接受致癌风险水平的上限,需要有效处理.

An electrical low-pressure imapctor （ELPI） and a portable PM2.5 sampler equipped with an air dilution system were employed to investigate the emission characteristics of PM2.5 from the cement manufacturing process. Three new dry cement manufacturing enterprises located in the northern China were chosen. Mass concentration and particle number concentration of PM2.5 emitted from the outlet of precipitator at the kiln head and the rear were examined, and concentration of PAHs in PM2.5 was also investigated. Afterwards, cancer risk levels resulting from PAHs inhalation were calculated. Experimental results showed that, the number concentration for PM0.33 accounted for over 70% of that for PM2.5. PAHs species in all sampling points were dominated by two-ring and three-ring PAHs. PAHs concentration sampled in the kiln head of Factory C was the highest, where BaP value exceeded the related national standard limited value （8ng/m3）, and its corresponding inhalation cancer risk was 4.46＆#215;10-4, much higher than the upper limit of carcinogenic level.