Coal-fired flue gas provides a very challenging environment for real-time measurementof mercury. Several Hg analyzers are commercially available that can measure elementalmercury vapor at typical concentrations found in coal combustion flue gas (1-20μg/Nm~3). For total vapor-phase mercury measurements, most of the analyzers mustconvert the non-elemental mercury to elemental mercury for measurement using thedistinct lines of florescence or ultraviolet (UV) absorption characteristic of elemental Hg.The analyzers are capable of identifying the species of mercury by removing the nonelementalforms prior to measurement. Unfortunately, no analyzer and sampleconditioning assembly has demonstrated the ability to continuously and accuratelymeasure mercury over long periods without significant operator interface in the harshcoal-fired flue gas environment since these assemblies are affected by one or more of theflue gas constituents.Apogee Scientific, Inc., through several research programs to evaluate mercury controloptions at coal-fired power plants funded by DOE and EPRI, has logged more than20,000 operating hours with cold-vapor atomic adsorption analyzers using wet-chemicalconversion systems. Through EPA and EPRI funding, Apogee is conducting a programto define a new state-of-the-art mercury measurement by developing a novel sampleconditioning system (SCS) that is not wet-chemistry based for the continuous real-timemonitoring of mercury in flue gas from coal-fired utility boilers. The proposed SCS willprovide a conditioning system for use with an analyzer such as a CVAAS or CVAFS tomeasure total vapor-phase mercury, elemental mercury, and total mercury (vapor plusparticulate) in real-time.This paper will present sampling techniques and results obtained using a wet-chemicalconversion system and results from initial field trials using the novel SCS.
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