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SELECTIVE CATALYTIC REDUCTION MERCURY FIELD SAMPLING PROJECT
Citation:
Laudal, D. L. SELECTIVE CATALYTIC REDUCTION MERCURY FIELD SAMPLING PROJECT. U.S. Environmental Protection Agency, Washington, DC, EPA/600/R-02/096, 2002.
Description:
The report details an investigation on the effect of selective catalytic reduction (SCR), selective noncatalytic reduction (SNCR), and flue gas conditioning on the speciation and removal of mercury at power plants. If SCR and/or SNCR systems enhance mercury conversion/capture, then they could be thought of as multipollutant control technologies. Pilot- scale tests investigated the role that coal type plays in mercury speciation, both with and without SCR. The results indicated that SCR, and possibly NH3 injection for flue gas conditioning, may enhance mercury capture, although it appeared that the impact was highly coal-specific. To validate and expand the pilot-scale results, six power plants were chosen for full-scale sampling. For a 10-12-day period, sampling was conducted both prior to and after the SCR unit and/or electrostatic precipitator using both the wet-chemistry Ontario Hydro method and near-real-time continuous mercury monitors. Additional samples were taken using EPA Method 26A for chlorides, a controlled condensation method to measure sulfur trioxide, and EPA Method 27 for NH3 slip. Fly ash and coal samples were also collected to obtain the mercury balance across the control devices. The results indicate that SCRs can assist in converting elemental mercury to oxidized mercury. However, the effect appears to be coal-specific and, possibly, catalyst-specific. NH3 injection, whether directly as a gas or indirectly as urea, did not appear to have a significant effect on mercury speciation and removal.