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A STUDY OF GAS-PHASE MERCURY SPECIATION USING DETAILED CHEMICAL KINETICS
Citation:
Edwards, J. R., R K. Srivastava*, AND J D. Kilgroe*. A STUDY OF GAS-PHASE MERCURY SPECIATION USING DETAILED CHEMICAL KINETICS. JOURNAL OF AIR & WASTE MANAGEMENT ASSOCIATION 51(6):869-877, (2001).
Description:
Mercury (Hg) speciation in combustion-generated flue gas is modeled using a detailed chemical mechanism consisting of 60 reactions and 21 species. This speciation model accounts for chlorination and oxidation of key flue-gas components, including elemental mercury. Results indicate that the performance of the model is very sensitive to temperature. Starting with pure hydrogen chloride (HCl), for lower reactor temperatures (less than approximately 630 degrees C), the model produces only trace amounts of atomic and molecular chlorine (Cl and Cl2), leading to a drastic under-prediction of Hg chlorination compared with experimental data. For higher reactor temperatures, model predictions are in good accord with experimental data. For conditions that produce an excess of Cl and Cl2 relative to Hg, chlorination of Hg is determined by competing influences of the initiation step Hg + Cl = HgCl and the chlorine recombination reaction 2Cl = Cl2. If the chlorine recombination reaction is faster, mercury chlorination will eventually be dictated by the slower pathway Hg + Cl2 = HgCl2.