Predicting extents of mercury oxidation in coal-derived flue gases
Journal Article
·
· Journal of the Air and Waste Management Association
- Niksa Energy Associates, Belmont, CA (US)
The extent of Hg oxidation determines the portion of Hg in the flue gas from a coal-fired power station that can be removed in SO{sub 2} scrubbers. This article evaluates predicted extents of Hg oxidation from a detailed chemical reaction mechanism, emphasizing the data from 1 and 29 MW pilotscale furnaces for diverse coal types. The proposed mercury (Hg) oxidation mechanism consists of a 168-step gas phase mechanism that accounts for interaction among all important flue gas species and a heterogeneous oxidation mechanism on unburned carbon (UBC) particles, similar to established chemistry for dioxin production under comparable conditions. The mechanism was incorporated into a gas cleaning system simulator to predict the proportions of elemental and oxidized Hg species in the flue gases, given relevant coal properties (C/H/O/N/S/Cl/Hg), flue gas composition (O{sub 2}, H{sub 2}O, HCl), emissions (NOx, SOx, CO), the recovery of fly ash, fly ash loss-on-ignition (LOI), and a thermal history. Predictions are validated without parameter adjustments against datasets from lab-scale and from pilot-scale coal furnaces at 1 and 29 MWt. Collectively, the evaluations cover 16 coals representing ranks from sub-bituminous through high-volatile bituminous, including cases with Cl{sub 2} and CaCl{sub 2} injection. The predictions are, therefore, validated over virtually the entire domain of Cl-species concentrations and UBC levels of commercial interest. Additional predictions identify the most important operating conditions in the furnace and gas cleaning system, including stoichiometric ratio, NOX, LOI, and residence time, as well as the most important coal properties, including coal-Cl. 33 refs., 4 figs., 3 tabs.
- OSTI ID:
- 20638630
- Journal Information:
- Journal of the Air and Waste Management Association, Journal Name: Journal of the Air and Waste Management Association Journal Issue: 7 Vol. 55; ISSN JAWAEB; ISSN 1047-3289
- Country of Publication:
- United States
- Language:
- English
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