Migration and emission characteristics of N-alkanes and phthalates in condensable particulate matter from coal-fired sources

Abstract

Condensable particulate matter (CPM) is the dominant component of the total particulate matter emitted from coal combustion. The organic pollutants contained in CPM are harmful substances, which pose significant potential threats to human health and the environment. CPM was sampled from eight coal-fired power units and two coal-fired industrial units, all with air pollution control devices (APCDs). The emission levels of n-alkanes and phthalates in CPM (C–N and C–P) and the influence of APCDs on the migration and distribution of the two organic pollutants were studied using a gas chromatograph/mass spectrometer. The average total concentrations of C–N and C–P was 425.68 μg/Nm3 and 73.35 μg/Nm3 in coal-fired power units, which was significantly lower than those in coal-fired industrial units (C–N, 2184.87 μg/Nm3; C–P, 1611.48 μg/Nm3). The mass concentration of C–N was always higher than that of C–P at the same sampling sites in all coal-fired units. The dry-type precipitators presented an excellent effect on the control of C–N (63.27%–92.86%) and C–P (21.29%–60.63%) from coal-fired units. Noted, the desulfurization system and the wet-type precipitators had opposite effects on the removal of two organic pollutants. Moreover, the emission concentrations of C–N and C–P decreased as the actual operating loads of the units increased, and the unit operating loads had a greater impact on the emission of C–N than on C–P. Flue gas temperature, dust content, and the dominant particle size of particulates are probably the significant factors that affect the concentration variation of C–N and C–P from coal combustion.