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Investigation of mercury transformation by HBr addition in a slipstream facility with real flue gas atmospheres of bituminous coal and Powder River Basin Coal

Journal Article · · Energy and Fuels
OSTI ID:20961441
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  1. Western Kentucky University, Bowling Green, KY (United States). Institute for Combustion Science and Environmental Technology
An investigation of speciated mercury transformation with the addition of hydrogen bromide (HBr) at elevated temperatures was conducted in a slipstream reactor with real flue gas atmospheres. Test results indicated that adding HBr into the flue gas at several parts per million strongly impacted the mercury oxidation and adsorption, which were dependent upon temperature ranges. Higher temperatures (in the range of 300-350 C) promoted mercury oxidation by HBr addition but did not promote mercury adsorption. Lower temperatures (in a range of 150-200 C) enhanced mercury adsorption on the fly ash by adding HBr. Test results also verified effects of flue gas atmospheres on the mercury oxidation by the addition of HBr, which included concentrations of chlorine and sulfur in the flue gas. Chlorine species seemed to be involved in the competition with bromine species in the mercury oxidation process. With the addition of HBr at 3 ppm at a temperature of about 330 C, the additional mercury oxidation could be reached by about 55% in a flue gas atmosphere by burning PRB coal in the flue gas and by about 20% in a flue gas by burning bituminous coal. These are both greater than the maximum gaseous HgBr2 percentage in the flue gas (35% for PRB coal and 5% for bituminous coal) by thermodynamic equilibrium analysis predictions under the same conditions. This disagreement may indicate a greater complexity of mercury oxidation mechanisms by the addition of HBr. It is possible that bromine species promote activated chlorine species generation in the flue gas, where the kinetics of elemental mercury oxidation were enhanced. However, SO{sub 2} in the flue gas may involve the consumption of the available activated chlorine species. Thus, the higher mercury oxidation rate by adding bromine under the flue gas by burning PRB coal may be associated with its lower SO{sub 2} concentration in the flue gas. 39 refs., 8 figs., 4 tabs.
OSTI ID:
20961441
Journal Information:
Energy and Fuels, Journal Name: Energy and Fuels Journal Issue: 5 Vol. 21; ISSN ENFUEM; ISSN 0887-0624
Country of Publication:
United States
Language:
English