Many utilities have added or will add selective catalytic reduction (SCR) systems and wet flue gas desulfuriza-tion (FGD) scrubbers to their plants for NO_x and SO_2 emissions control, respectively. Having addressed these airborne pollutant emissions, utilities are now focusing on mercury (Hg) emissions control. Fortunately, the combination of an SCR and wet FGD scrubber can also provide significant mercury emissions reduction for utility boilers. In fact, under the right conditions, this combination has the potential to be an effective compliance option for mercury emissions under the Clean Air Mercury Rule. This article analyzes the capabilities and limitations of the SCR-FGD combination for mercury compliance, including applicability to different types of coals and issues with scrubber by-products.
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