Influence of flue gas desulfurization (FGD) installations on emission characteristics of PM from coal-fired power plants equipped with selective catalytic reduction (SCR).

Flue gas desulfurization (FGD) and selective catalytic reduction (SCR) technologies have been widely used to control the emissions of sulphur dioxide (SO) and nitrogen oxides (NO) from coal-fired power plants (CFPPs). Field measurements of emission characteristics of four conventional CFPPs indicated a significant increase in particulate ionic species, increasing PM emission with FGD and SCR installations. The mean concentrations of PM from all CFPPs tested were 3.79 ± 1.37 mg/m and 5.02 ± 1.73 mg/m at the FGD inlet and outlet, respectively, and the corresponding contributions of ionic species were 19.1 ± 7.7% and 38.2 ± 7.8%, respectively. The FGD was found to enhance the conversion of NH slip from the SCR to NH in the PM, together with the conversion of SO to SO, and increased the primary NH and SO aerosol emissions by approximately 18.9 and 4.2 times, respectively. This adverse effect should be considered when updating the emission inventory of CFPPs and should draw the attention of policy-makers for future air pollution control.