EVALUATION OF AN ALTERNATIVE METHOD TO THE ONTARIO HYDRO FORMERCURY SPECIATION IN STACK EMISSIONS

摘要

A filter-based Mercury Speciation Cassette (MSC) has been developed which is capable of accurately andeasily speciating mercury concentrations in stack emissions. During 2003, the MSC was tested againstEPA's standard Ontario-Hydro (OH) method at a Midwest coal-fired power plant. The MSC had arelative accuracy of 12%, demonstrated a precision that was 30% better than the listed OH precision, andshowed an average of only 4% difference in the percent elemental mercury. Blind tests relative tostandard gas canisters demonstrated a recovery of better than 98% for elemental mercury while tests at anOregon CFPP indicated trapping efficiencies of better than 99% for mercury concentrations greater than300 μg/dscm.The MSC approach offers a number of advantages over the standard OH method including:? Detection limits of better than 0.1 micrograms/dscm for 50 minutes of sampling? Sampling, analysis and sample recovery are completed without use of chemicals? Sampling can be conducted by one operator? Cassettes can be changed within five minutes? Filter samples can be sent via FedEx for next day analysis? Low per-run analysis cost? Turn-around-times can be as low as 24 hours? Potential exists for in-field XRF analysis for same day results? XRF analysis is non-destructive, so filters can be archived and reanalyzed at a later date orverified by an alternative method