(45b) Mercury Emission Reduction: Performance and Economic Analysis

While State and Federal agencies make progress toward establishing regulations for Hazardous Air Pollutants, it is certain that coal-fired utilities will be required to reduce mercury emissions in the near future. Utilities therefore are seeking cost effective mercury control strategies.  Powdered activated carbon (PAC) is a common strategy to remove mercury from combustion flue gas, but it burdens existing air quality control devices and can ruin ash quality for concrete applications.  Specialty PAC formulations have been developed to maintain ash quality, but these are expensive. The application of Nalco MerControl 7895, with or without PAC, is shown to successfully meet current and anticipated mercury emission regulations while reducing overall operation and maintenance costs.  

An example of meeting emission regulations and minimizing cost is provided by the commercial demonstration carried out on a 580 MWe coal-fired boiler burning PRB coal and equipped with low-NO_x burners, an SCR for NO_x control, a dry scrubber for SO₂ control, and a pulse-jet fabric filter for particulate control.  The result of the demonstration was mercury emission control below the required 1.0 lb/TBtu at a cost less than using halogenated PAC.  The optimized application of MerControl 7895 in conjunction with PAC resulted in a $1 million per year savings compared to the use of halogenated PAC for mercury emission compliance.

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