Fundamentals of Mercury Speciation and Control in Coal-Fired Boilers

摘要

The report describes the progress of an experimental investigation of thespeciation of mercury in simulated coal combustion flue gases. The effects of flue gas parameters and coal fly ash on the oxidation of elemental mercury (Hgo) in the presence of hydrogen chloride (CHl) in a simulated post-combustion region including the baghouse portion of air pollution control systems, were studied using a bench-scale setup. Results of the gas-phase experiments indicate that the in-flight post-combustion oxidation of Hgo in the presence of HCl in a simulated flue gas is slow and proceeds at measurable rates only at high temperatures (> 700 C) and high HCl concentrations (> 200 ppmv). The effects of the coal fly ash component and its compostion were investigated using a fixed bed of model fly ashes. The primary focus was to evaluate the catalytic activity of major mineral constituents of coal fly ashes. Copper and iron oxides were the only two components that exhibited significant catalytic activity toward surface-mediated oxidation of Hgo.