Control of gaseous mercury emissions from combustion sources is a major environmental concern facing power generators. The removal of mercury by conversion to HgCl2 and HgBr2 is evaluated with an elementary reaction mechanism (852 reactions, 156 species) developed from fundamental principles of thermodynamics and statistical mechanics. Thermochemistry and rate constants are from literature, or calculated at the M06-2X/aug-cc-pVTZ-PP (mercury species), and CBS-QB3 (non-mercury species) levels of theory. Pressure dependence of chemical activated reactions is included by the QRRK analysis for k(E) and Master Equation for fall-off. Thermochemistry on Hg halides, oxides, and Hg-NOx-X and Hg-SOx-X (X=Cl,Br) has been determined, and kinetics incorporated in the mechanism. The efficiency of Cl2 and Br2 to convert Hgo (non-soluble) into Hg+2 (soluble) is studied in typical combustion effluents, and show Br2 is more effective than Cl2. Results illustrate that NOx-, SOx-Halogen reactions result in loss of halogen atoms, and lower Hg Conversion.

Kinetic modeling of gas-phase mercury oxidation by halides (Cl and Br) in combustion effluents: The importance of NOx and SOx

245th National Meeting (2013)

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