Trace element distribution and mercury speciation in a pilot-scale coal combustor burning Blacksville coal

A series of tests have been conducted on a nominal 500-pound-per-hour, pilot-scale combustion unit to characterize trace element emissions and mercury speciation. The coal fired during the testing was a Blacksville {number_sign}2, medium-sulfur coal, similar to that used by other researchers investigating mercury speciation. A description of the pilot unit operating conditions during the testing is provided. A summary of the gas/solid distribution of trace elements at various locations within the system, material balances, and baghouse removal efficiencies is also supplied. EPA Method 29 was used to determine trace element and speciated mercury concentrations before and after the baghouse. A comparison of these results with past trace element results from this unit and with the findings of other researchers who have used Blacksville coal is also presented. The pilot-scale combustion unit has been characterized in terms of trace element distribution during two tests while burning a medium-sulfur bituminous Blacksville coal. EPA sampling methodology at the inlet to the baghouse and at the stack was used. Results indicate that most of the elements are removed across the baghouse with the exception of mercury and selenium. Both of these elements were found predominantly in the vapor phase. The average mercury speciation revealedmore » that the vapor-phase mercury was primarily in the oxidized form, which is consistent with the findings of other research with Blacksville coal. Material recoveries for most of the elements were very good. The average recovery for mercury further validates that this pilot unit will be a viable system for mercury sampling and control methods.« less