Polycyclic aromatic hydrocarbons and normal alkanes in condensable particulate matter of coal combustion

Abstract

Currently, there is relatively limited research on the organic components of condensable particulate matter (CPMo). This work quantitatively investigated two typical CPMo: high-toxic polycyclic aromatic hydrocarbons (PAHs) and high-content normal alkanes (n-alkanes). The effects of oxygen content (OC) and exhaust temperature (ET) on their emission concentrations were explored. The results showed that the percentage of CPMo in this work were relatively large, averaging 81.22% in different operating conditions. CPMo were greatly affected by the OC. Under different OC and ET conditions, PAHs in CPMo were mainly concentrated in 4- and 5-ring, with a relatively small proportion in others. The minimum amount of PAHs was generated under the high OC and the low ET condition. After analyzing the toxic equivalent quantity (TEQ), it was found that 5-ring PAHs were the largest contributors to TEQ, followed by 4- and 6-ring PAHs. PAHs with higher concentrations do not necessarily have higher toxicity. In addition, the emission concentration of n-alkanes showed a unimodal distribution under different conditions, with the highest concentration of n-alkanes between C22 and C32. The concentration of n-alkanes gradually increased as the ET decreased and the OC increased.