| dc.description.abstract | Coal-fired boilers and steel industry are crucial for economic development, however, emissions of NOx, SOx, PM and PAHs from these industries pose significant impact on local air quality. In this study, two coal-fired boilers (Boilers A and B) and steel-making processes including sintering process (SP) and electric arc furnace (EAF) are selected for sampling and analysis to evaluate the performance of APCDs adopted and the emission characteristics of PM, PM2.5 (FPM and CPM), SOx, NOx, and PAHs. The results show that the concentrations of NOx emitted from Boiler A and B are 59 and 15 ppm, respectively, and the removal efficiency of NOx achieved with Boiler A (η= 47.2%) is lower than that of boiler B (η=84.3%), and the NOx emitted from Boiler A is slightly higher than the BACT standard (30 ppm). The NOx concentration emitted from the SP is 43 ppm and the NOx removal efficiency is 57.8%, which is lower than the expected performance of SCR (η= 80%). Removal efficiencies of SOx achieved with WFGD of two coal-fired boilers are 99%. The SOx concentration emitted from the SP is 17 ppm, while the concentrations of NOx and SOx measured at EAF outlet are lower than 1 ppm. The FPM concentrations measured at stacks of Boiler A and B are 0.9 and 0.4 mg/Nm3, respectively, and the removal efficiencies of FPM are 99.9%. On the other hand, the FPM concentrations measured at the stacks of SP and EAF are 8.2 mg/Nm3 and 13.6 mg/Nm3, respectively. The FPM emitted from EAF is slightly higher than the BACT standard (10 mg/Nm3). The FPM2.5 emitted from both coal-fired boilers are < 0.09 mg/Nm3. FPM2.5 emitted from the SP is measured as 1.8 mg/Nm3, which is lower than that emitted from EAF (3.2 mg/Nm3). It shows that the FPM concentration emitted from the steel-making processes are higher than that of coal-fired boilers. The CPM emitted from coal-fired boilers A and B are 37.4 and 14.7 mg/Nm3, respectively, and those from SP and EAF are 37.7 and 3.4 mg/Nm3, respectively, indicating that CPM emitted from coal-fired boilers and steel-making processes are higher than FPM and deserve more attention. The PAHs concentration measured at the stack of coal-fired boiler A is 547 ng/Nm3, while those measured at SP and EAF are 62.6 and 136 μg/Nm3, respectively. The concentrations of gas-phase PAHs are higher than that of solid-phase PAHs, and are primarily composed of 2-3 ring, and existing APCDs cannot efficiently remove gas-phase PAHs. The toxic concentrations of PAHs emitted from steel-making processes (4.74-5.45 μg-BaPeq/Nm3) are significantly higher than those emitted from coal-fired boilers (39.7 ng-BaPeq/Nm3). In addition, this study shows that the PAHs of the coal-fired boiler is easily enriched in fine particles. On the other hand, the emission factors of FPM from coal-fired boiler and SP are significantly lower than other reports. However, the emission factors of particulate matter from EAF are relatively high. The emission factors of CPM from coal-fired boiler and steel-making processes are much higher than those of FPM. Moreover, the emission factors of PAHs in SP and EAF are significantly higher than those of coal-fired boilers, indicating there is room for improvement. PCA analysis results show that PAHs characteristic species of coal-fired boiler and steel-making process are 4-6 ring PAHs. | en_US |