Abstract: “The U.S. Environmental Protection Agency (EPA) and World Health Organization (WHO) along with several published reports have identified mercury as a hazardous air pollutant leading to the EPA establishing Mercury and Air Toxics Standards (MATS) for coal-fired electricity generating units (EGUs) that take effect in 2015. Currently over 50% of the existing coal-fired EGUs based on capacity utilize wet flue gas desulfurization systems (WFGDs) to reduce sulfur dioxide emissions. WFGDs represent existing air quality control devices (AQCDs) that as part of a mercury emissions control strategy, can facilitate EGU mercury compliance.
This white paper focuses on EGUs that contain WFGDs and their utilization as part of a MATS mercury compliance strategy. In particular, our focus is limited to wet-scrubbed units with highly oxidized mercury flue gas entering the WFGD that are not attaining or are only marginally attaining mercury emission limitations.”
The EPA refers to activated carbon as “the most successfully demonstrated mercury-specific control technology” that also has minimal installation requirements. Within this industry, bromine and other halogens are typically applied to the activated carbon to enhance mercury oxidation and capture. However, the corrosive nature of these additives has the potential to cause larger issues for power plants with extended use. Carbonxt testing with carbon tailoring and alternative additives have shown to achieve the same or better performance results while maintaining the integrity of the plant. Recent full-scale tests have been conducted that include a span of coal and boiler types, injection location/particulate control configurations, injection rates, and concentration of SO3 (inherent and injected for flue-gas conditioning). This presentation will review the mercury control performance and operational impacts, including particle emissions and fly ash utilization, of these recent test events.
With the introduction of the first national standards for mercury pollution from power plants in December of 2011, many facilities will turn to activated carbon injection to meet the regulatory demands. Activated carbon injection is a mature technology that is widely available and proven for achieving mercury removal greater than 90%. In anticipation of the need, Carbonxt has developed powdered activated carbon for mercury removal from coal-fired power plant flue gas. This product stands apart from most available mercury control sorbents in that is it non-halogenated. The Carbonxt product has been tested using full-scale activated carbon injection studies under various conditions. The testing includes a span of coal and boiler types, injection location/particulate control configurations, injection rates, and concentration of SO3 (inherent and injected for flue-gas conditioning). This presentation will review the mercury control performance and operational impacts, including particle emissions and fly ash utilization, of these recent test events.