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Title: The impact of wet flue gas desulfurization scrubbing on mercury emissions from coal-fired power stations

Abstract

The article introduces a predictive capability for mercury (Hg) retention in any Ca-based wet flue gas desulfurization (FGD) scrubber, given Hg speciation at the FGD inlet, the flue gas composition, and the sulphur dioxide (SO{sub 2}) capture efficiency. A preliminary statistical analysis of data from 17 full-scale wet FGDs connects flue gas compositions, the extents of Hg oxidation at FGD inlets, and Hg retention efficiencies. These connections show that solution chemistry within the FGD determines Hg retention. A more thorough analysis based on thermochemical equilibrium yields highly accurate predictions for total Hg retention with no parameter adjustments. For the most reliable data, the predictions were within measurement uncertainties for both limestone and Mg/lime systems operating in both forced and natural oxidation mode. With the U.S. Environmental Protection Agency's (EPA) Information Collection Request (ICR) database, the quantitative performance was almost as good for the most modern FGDs, which probably conform to the very high SO{sub 2} absorption efficiencies assumed in the calculations. The large discrepancies for older FGDs are tentatively attributed to the unspecified SO{sub 2} capture efficiencies and operating temperatures and to the possible elimination of HCl in prescrubbers. The equilibrium calculations suggest that Hg retention is most sensitive tomore » inlet HCl and O{sub 2} levels and the FGD temperature; weakly dependent on SO{sub 2} capture efficiency; and insensitive to HgCl{sub 2}, NO, CA:S ratio, slurry dilution level in limestone FGDs, and MgSO{sub 3} levels in Mg/lime systems. Consequently, systems with prescrubbers to eliminate HCl probably retain less Hg than fully integrated FGDs. The analysis also predicts re-emission of Hg{sub 0} but only for inlet O{sub 2} levels that are much lower than those in full-scale FGDs. 12 refs., 5 figs., 3 tabs.« less

Authors:
;  [1]
  1. Niksa Energy Associates, Belmont, CA (US)
Publication Date:
OSTI Identifier:
20638631
Resource Type:
Journal Article
Journal Name:
Journal of the Air and Waste Management Association
Additional Journal Information:
Journal Volume: 55; Journal Issue: 7; Other Information: neasteve@pacbell.net; Journal ID: ISSN 1047-3289
Country of Publication:
United States
Language:
English
Subject:
01 COAL, LIGNITE, AND PEAT; 20 FOSSIL-FUELED POWER PLANTS; FLUE GAS; DESULFURIZATION; MERCURY; EMISSION; COAL; RETENTION; FOSSIL-FUEL POWER PLANTS; SCRUBBERS; CHEMICAL COMPOSITION; OXIDATION; EFFICIENCY; REGRESSION ANALYSIS; PREDICTION EQUATIONS; LIMESTONE; LIME-LIMESTONE WET SCRUBBING PROCESSES; PARAMETRIC ANALYSIS; MERCURY CHLORIDES; HYDROCHLORIC ACID

Citation Formats

Niksa, Stephen, and Fujiwara, Naoki. The impact of wet flue gas desulfurization scrubbing on mercury emissions from coal-fired power stations. United States: N. p., 2005. Web. doi:10.1080/10473289.2005.10464689.
Niksa, Stephen, & Fujiwara, Naoki. The impact of wet flue gas desulfurization scrubbing on mercury emissions from coal-fired power stations. United States. https://doi.org/10.1080/10473289.2005.10464689
Niksa, Stephen, and Fujiwara, Naoki. 2005. "The impact of wet flue gas desulfurization scrubbing on mercury emissions from coal-fired power stations". United States. https://doi.org/10.1080/10473289.2005.10464689.
@article{osti_20638631,
title = {The impact of wet flue gas desulfurization scrubbing on mercury emissions from coal-fired power stations},
author = {Niksa, Stephen and Fujiwara, Naoki},
abstractNote = {The article introduces a predictive capability for mercury (Hg) retention in any Ca-based wet flue gas desulfurization (FGD) scrubber, given Hg speciation at the FGD inlet, the flue gas composition, and the sulphur dioxide (SO{sub 2}) capture efficiency. A preliminary statistical analysis of data from 17 full-scale wet FGDs connects flue gas compositions, the extents of Hg oxidation at FGD inlets, and Hg retention efficiencies. These connections show that solution chemistry within the FGD determines Hg retention. A more thorough analysis based on thermochemical equilibrium yields highly accurate predictions for total Hg retention with no parameter adjustments. For the most reliable data, the predictions were within measurement uncertainties for both limestone and Mg/lime systems operating in both forced and natural oxidation mode. With the U.S. Environmental Protection Agency's (EPA) Information Collection Request (ICR) database, the quantitative performance was almost as good for the most modern FGDs, which probably conform to the very high SO{sub 2} absorption efficiencies assumed in the calculations. The large discrepancies for older FGDs are tentatively attributed to the unspecified SO{sub 2} capture efficiencies and operating temperatures and to the possible elimination of HCl in prescrubbers. The equilibrium calculations suggest that Hg retention is most sensitive to inlet HCl and O{sub 2} levels and the FGD temperature; weakly dependent on SO{sub 2} capture efficiency; and insensitive to HgCl{sub 2}, NO, CA:S ratio, slurry dilution level in limestone FGDs, and MgSO{sub 3} levels in Mg/lime systems. Consequently, systems with prescrubbers to eliminate HCl probably retain less Hg than fully integrated FGDs. The analysis also predicts re-emission of Hg{sub 0} but only for inlet O{sub 2} levels that are much lower than those in full-scale FGDs. 12 refs., 5 figs., 3 tabs.},
doi = {10.1080/10473289.2005.10464689},
url = {https://www.osti.gov/biblio/20638631}, journal = {Journal of the Air and Waste Management Association},
issn = {1047-3289},
number = 7,
volume = 55,
place = {United States},
year = {Fri Jul 01 00:00:00 EDT 2005},
month = {Fri Jul 01 00:00:00 EDT 2005}
}