Removal of Selenium From FGD Scrubber Purge Water

Castaldi, Frank J.; Behrens, Gregory P.; Hargrove, O.W.

doi:10.2175/193864701790861172

Cited by 6 publications

(3 citation statements)

References 5 publications

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“…However, the mass content of Se in CPM does not change obviously through ammonia-based WFGD, and that increases at the stack through limestone-based WFGD and WESP, which may be because of the complex reaction of the Se chemistry in WFGD or WESP. The solubility of SeO 2 results in its accumulation in liquid fractions, and S 2 O 3 2– reacts with Se to form SeS 2 O 3 2– and Se(S 2 O 3 ) 2 2– under limited O 2 conditions, which increases the concentration of dissolved Se. , For ammonia-based WFGD, the solubility of NH 4 HSO 3 is higher than that of Ca(HSO 3 ) 2 in limestone-based WFGD. Se will be predominantly in the form of H 2 SeO 3 since the reaction of SeO 2 with moisture in flue gas or diffusion gaseous SeO 2 from gas to the aqueous phase, thus may react with HSO 3 – to form an array of Se–S stable compounds and/or isomers. ,, These abovementioned complex chemical reactions under high-humidity conditions and flue gas entrainment may increase the content of Se in CPM through the limestone-based WFGD and WESP.…”

Section: Resultsmentioning

confidence: 99%

“…The solubility of SeO 2 results in its accumulation in liquid fractions, and S 2 O 3 2− reacts with Se to form SeS 2 O 3 2− and Se(S 2 O 3 ) 2 2− under limited O 2 conditions, which increases the concentration of dissolved Se. 47,49 For ammonia-based WFGD, the solubility of NH 4 HSO 3 is higher than that of Ca(HSO 3 ) 2 in limestone-based WFGD. Se will be predominantly in the form of H 2 SeO 3 since the reaction of SeO 2 with moisture in flue gas or diffusion gaseous SeO 2 from gas to the aqueous phase, thus may react with HSO 3 − to form an array of Se−S stable compounds and/or isomers.…”

Section: ■ Results and Discussionmentioning

confidence: 99%

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Non-Negligible Stack Emissions of Noncriteria Air Pollutants from Coal-Fired Power Plants in China: Condensable Particulate Matter and Sulfur Trioxide

Bai

Liu

et al. 2020

Environ. Sci. Technol.

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In this study, we investigated the emission characteristics of condensable particulate matter (CPM) and sulfur trioxide (SO3) simultaneously through ammonia-based/limestone-based wet flue gas desulfurization (WFGD) from four typical coal-fired power plants (CFPPs) by conducting field measurements. Stack emissions of filterable particulate matter (FPM) all meet the Chinese ultralow emission (ULE) standards, whereas CPM concentrations are prominent (even exceed 10 mg/Nm3 from two CFPPs). We find that NH4 + and Cl– increase markedly through the ammonia-based WFGD, and SO4 2– is generally the main ionic component, both in CPM and FPM. Notably, the occurrence of elemental Se in FPM and CPM is significantly affected by WFGD. Furthermore, the established chemical profiles in FPM and CPM show a distinct discrepancy. In CPM, the elemental S mainly exists as a sulfate, and the metallic elements of Na, K, Mg, and Ca mainly exist as ionic species. Our results may indicate that not all SO3 are included in CPM and they co-exist in stack plume. With the substantial reduction of sulfur dioxide (SO2), S distributed in SO3, CPM, and FPM becomes non-negligible. Finally, the emission factors of CPM and SO3 under typical ULE technical routes fall in the ranges of 74.33–167.83 and 48.76–86.30 g/(t of coal) accordingly.

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Section: Resultsmentioning

confidence: 99%

Section: ■ Results and Discussionmentioning

confidence: 99%

Non-Negligible Stack Emissions of Noncriteria Air Pollutants from Coal-Fired Power Plants in China: Condensable Particulate Matter and Sulfur Trioxide

Bai

Liu

et al. 2020

Environ. Sci. Technol.

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“…As a matter of fact, the WFGD absorbent is a very complex system that contains various ions. One of the important ions is Cl – , which would accumulate and had the concentration at a very high level. , Therefore, the impact of Cl – on Hg 0 re-emission in the coexistence systems of SO 3 2– and NO 2 – is also needed to be considered. Figure illustrated that even very little amount of Cl – (2 mM) could effectively inhibit the emission of Hg 0 .…”

Section: Resultsmentioning

confidence: 99%

Mercury Re-Emission in Flue Gas Multipollutants Simultaneous Absorption System

Liu

Wang

Mei

et al. 2014

Environ. Sci. Technol.

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Recently, simultaneous removal of SO2, NOx and oxidized mercury in wet flue gas desulfurization (WFGD) scrubber has become a research focus. Mercury re-emission in traditional WFGD system has been widely reported due to the reduction of oxidized mercury by sulfite ions. However, in multipollutants simultaneous absorption system, the formation of a large quantity of nitrate and nitrite ions as NOx absorption might also affect the reduction of oxidized mercury in the aqueous absorbent. As such, this paper studied the effects of nitrate and nitrite ions on mercury re-emission and its related mechanism. Experimental results revealed that the nitrate ions had neglected effect on mercury re-emission while the nitrite ions could greatly change the mercury re-emission behaviors. The nitrite ions could initially improve the Hg(0)-emission through the decomposition of HgSO3NO2(-), but with a further increase in the concentration, they would then inhibit the reduction of bivalent mercury owing to the formation of Hg-nitrite complex [Hg(NO2)x(2-x)]. In addition, the subsequent addition of Cl(-) could further suppress the Hg(0) emission, where the formation of a stable Hg-SO3-NO2-Cl complex was assumed to be the main reason for such strong inhibition effect.

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Aqueous Behavior of Elements in a Flue Gas Desulfurization Sludge Disposal Site

Castaldi¹

2004

Water Encyclopedia

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Flue gas desulfurization (FGD) systems are end of process pollution abatement techniques used primarily for removing sulfur dioxide from coal‐fired utility and industrial boiler combustion gases. The technology has also been successfully applied to Claus sulfur recovery unit tail gas and sulfuric acid plant tail gas streams. Sulfur dioxide (SO 2 ) and particulate emissions are controlled by a flue gas scrubber system. The scrubber is often designed as an integral part of the steam generation plant. It consists of a two‐stage venturi‐absorber scrubber module designed to treat boiler flue gas. The flue gas from the boiler enters the air quality control system through a common plenum. The gas stream is sent to the individual scrubber modules from this plenum.

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Removal of Selenium From FGD Scrubber Purge Water

Cited by 6 publications

References 5 publications

Non-Negligible Stack Emissions of Noncriteria Air Pollutants from Coal-Fired Power Plants in China: Condensable Particulate Matter and Sulfur Trioxide

Non-Negligible Stack Emissions of Noncriteria Air Pollutants from Coal-Fired Power Plants in China: Condensable Particulate Matter and Sulfur Trioxide

Mercury Re-Emission in Flue Gas Multipollutants Simultaneous Absorption System

Aqueous Behavior of Elements in a Flue Gas Desulfurization Sludge Disposal Site

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