Measured Particulate, HCl, and Hg Emissions from Circulating Dry Scrubbers Compared to the EPA Mercury Air Toxic Standards

摘要

Circulating Dry Scrubbers (CDS) installed at four coal-fired electric generating units (EGUs) removed ≥ 96% of the inlet SO_2 and controlled hazardous air pollutants (HAPS) emissions below recently signed EPA Mercury Air Toxic Standards (MATS) for existing coal-fired EGUs. The HAPS controlled by the CDS systems included particulate, HC1, mercury, SO_3 and HF. Mercury emission was controlled to levels below existing-EGU MATS without injecting activated carbon. The EPA MATS include very challenging emission limits for new EGUs. The limits for new EGUs are 43 to 65 times lower for particulate, HC1, and Hg than for existing EGUs. The CDS systems installed on the existing EGUs were not required to meet the new EGU limits. Nevertheless, the CDS controlled SO_2, particulate and Hg to levels at or approaching the new-EGU MATS during parametric tests. We also note that it would be difficult to reliably measure the new-EGU limits for HC1 and Hg.