Evaluation of Mercury Speciation at Power Plants Using SCR and SNCR NOx Control Technologies
The proposed project addresses the question, What is the impact that SCR, SNCR, or flue gas conditioning systems have on total mercury emissions and on the speciation of mercury? Based on the Information Collection Request (ICR) results to date, it appears that there is a significant lack of good information on mercury speciation for coal-fired plants that have low-NOx systems. Selective catalytic reduction (SCR) units have the potential to achieve high levels of NOx reduction by reducing NOx to N2 and H2O in the presence of a catalyst, vanadium/tungsten - titanium metal oxide. Bench and pilot-scale testing indicates that metal oxides, including vanadium and titanium, have the potential to promote the formation of oxidized Hg and/or particulate-bound mercury in relatively simple flue gas mixtures. The SNCR (selective noncatalytic reduction) process is similar to the SCR approach but uses a reagent, most likely urea, to react with the NOx to form N2 and H2O. Therefore, mercury speciation impacts could be different for SCR and SNCR.

Determination of the Speciated Mercury Inventory at Four Coal-Fired Boilers Using Continuous Mercury Monitors
Midwest Generation (MG) has net equity ownership in approximately 14,000 MW of coal-fired capacity, of which about 7500 MW is located in the United States. Given EPA’s recent positive determination regarding the future regulation of mercury emissions and MG desire to be environmentally proactive, MG is intending to conduct mercury sampling at several of its U.S. coal-fired power stations. The purpose is to be able to develop a projection of MG total inventory of U.S. mercury emissions (total emissions as well as speciation). Based upon the projected emissions from each of its coal-fired facilities and anticipated future EPA mercury emissions, MG intends to identify the optimum retrofit mercury control technologies for each of its plants.

The objective of this Energy & Environmental Research Center project is to provide MG with the information it needs to develop mercury inventory data and determine the mercury variability. At the same time, the ability of continuous mercury monitors (CMM) to provide this type of data will be evaluated. The results from the CMM(s) will be verified using the Ontario Hydro (OH) mercury speciation method.

Longer-Term Testing of Continuous Mercury Monitors
In late 2000, EPA issued a report stating that it intended to regulate mercury emissions from coal-fired electric utility boilers. Therefore, accurate, reliable, and economical methods of measuring mercury will be required. Currently EPA Method 29 and EPA Method 101A (for total mercury) and the Ontario Hydro (OH) mercury speciation method (speciated mercury) wet-chemistry methods are used. Although these methods provide good results with a high level of sensitivity (<0.5 μg/Nm³), they have several major disadvantages:

• They require a high level of quality assurance/quality control (QA/QC) and well-trained personnel.
• They provide no real-time data and often have 2-week or more turnaround times for results.
• They are expensive.
• They do not provide long-term results showing mercury emission variations.

Therefore, automated on-line mercury analyzers are being developed to measure both total and speciated mercury emissions. These analyzers are based on well-established techniques, including cold-vapor atomic absorption spectroscopy (CVAAS), cold-vapor atomic fluorescence spectroscopy (CVAFS), and atomic emission spectroscopy (AES), as well as on the emerging technology of chemical microsensors. Although bench-, pilot-, and full-scale data have been generated that show the potential of these instruments to provide accurate, reliable results, all work has been short term, 1 week or less. Longer-term continuous information for these instruments is needed. This Energy & Environmental Research Center (EERC) proposal is to conduct 25B 30-day tests utilizing different continuous (or near-continuous) mercury monitors (CMMs).

OBJECTIVES
The overall objective of the project is to provide longer-term data to determine the reliability and ruggedness of CMMs at two power stations: First Energy' s Sammis Plant and Texas Utilities' (TU) Monticello Plant. In addition, to determine accuracy, several OH mercury speciation method samples will be taken.