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Show Table 1 - Furnace Mercury Emissions and Partitioning Coal Ohio 5&6 Mahoning 7 Ohio 6A Meigs Creek Ohio 5,6,&7 Clarion 4A Flue Gas Temperature (°F) 333 328 342 358 342 359 Total Mercury (|ig/dscm) 17.6 22.3 20.1 11.2 23.5 23.0 Vapor Phase (%) 88.8 74.4 93.8 95.2 72.1 84.4 Filter Catch (%) 11.2 25.6 6.2 4.8 27.9 15.6 Fly Ash LOI (Loss-On- Ignition) (%) 2.5 5.7 5.0 1.8 3.4 4.0 On average, approximately 1 5 % of the total mercury was present on the particulate collected in the sampling train for the bituminous coals fired. For the narrow range of relatively low LOI values in these tests, the distribution of mercury between the vapor phase and the particulate did not appear to be strongly correlated with fly ash LOI. Coal Cleaning Impacts The total mercury emissions shown in Table 1 represent those from the combustion of commercially cleaned, high-sulfur eastern bituminous coals. For three of these coals (Ohio 5&6, Ohio 6A, and Meigs Creek), chemical analyses were performed on the raw and cleaned coals to evaluate the effects of commercial cleaning on mercury emissions. The total emissions in Table 1 match well with predicted emissions based on the coal chemistry and the assumption that all of the mercury exits the furnace. Comparison of the emissions to those predicted for firing the raw Ohio bituminous coals indicated that the average reduction in mercury emissions resulting from the cleaning processes was 49 percent, with a range from 45 to 56 percent. This range can be expected to vary with different types of coals having more or less mercury associated with the inorganic fraction. Vapor Phase Mercury Speciation The distributions of vapor phase mercury species in the flue gas at the air pre-heater outlet measured for the Ohio 5&6, Ohio 6A, and Meigs Creek coals presented in Table 1 at the indicated flue gas temperatures. The speciation measurements using the Ontario Hydro Method are summarized in Figure 3. For these bituminous coals, the vapor phase mercury is primarily 5 |
