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Title: REDUCTION OF INHERENT MERCURY EMISSIONS IN PC COMBUSTION

Abstract

Mercury emission compliance presents one of the major potential challenges raised by the 1990 Clean Air Act Amendments. Simple ways of controlling emissions have not been identified. The variability in the field data suggest that inherent mercury emissions may be reduced if the source of this inherent capture can be identified and controlled. The key mechanisms appear to involve the oxidation of mercury to Hg{sup 2}, generally producing the more reactive HgCl{sub 2}, followed by its capture by certain components of the fly ash or char, or in the air pollution control equipment. This research focuses on identifying the rate-limiting steps associated with the oxidation step. Work in this reporting period focused on testing of the kinetic mechanism reported in the previous semiannual report, and the interpretation of data (both ours and literature). This model yields good qualitative agreement with the data and indicates that mercury oxidation occurs during the thermal quench of the combustion gases. The model also suggests that atomic chlorine is the key oxidizing species. The oxidation is limited to a temperature window between 700-400 C that is defined by the overlap of (1) a region of significant superequilibrium Cl concentration, and (2) a region where oxidizedmore » mercury is favored by equilibrium. Above 700 C reverse reactions effectively limit oxidized mercury concentrations. Below 400 C, atomic chlorine concentrations are too low to support further oxidation. The implication of these results are that homogeneous oxidation is governed primarily by (1) HCl concentration, (2) quench rate, and (3) background gas composition. Work conducted under the present grant has been the subject of one journal paper that was accepted for publication during the reporting period (Sliger et al., 1999).« less

Authors:
; ;
Publication Date:
Research Org.:
Federal Energy Technology Center, Morgantown, WV (US); Federal Energy Technology Center, Pittsburgh, PA (US)
Sponsoring Org.:
US Department of Energy (US)
OSTI Identifier:
775020
Report Number(s):
DE-FG22-95PC95216-08
TRN: AH200110%%36
DOE Contract Number:  
FG22-95PC95216
Resource Type:
Technical Report
Resource Relation:
Other Information: PBD: 6 Aug 1999
Country of Publication:
United States
Language:
English
Subject:
01 COAL, LIGNITE, AND PEAT; AIR POLLUTION CONTROL; CHLORINE; COMBUSTION; FLY ASH; GASES; MERCURY; OXIDATION; COAL; PULVERIZED FUELS; MERCURY CHLORIDES; CHEMICAL REACTION KINETICS; MATHEMATICAL MODELS

Citation Formats

John C. Kramlich, Rebecca N. Sliger, and David J. Going. REDUCTION OF INHERENT MERCURY EMISSIONS IN PC COMBUSTION. United States: N. p., 1999. Web. doi:10.2172/775020.
John C. Kramlich, Rebecca N. Sliger, & David J. Going. REDUCTION OF INHERENT MERCURY EMISSIONS IN PC COMBUSTION. United States. doi:10.2172/775020.
John C. Kramlich, Rebecca N. Sliger, and David J. Going. Fri . "REDUCTION OF INHERENT MERCURY EMISSIONS IN PC COMBUSTION". United States. doi:10.2172/775020. https://www.osti.gov/servlets/purl/775020.
@article{osti_775020,
title = {REDUCTION OF INHERENT MERCURY EMISSIONS IN PC COMBUSTION},
author = {John C. Kramlich and Rebecca N. Sliger and David J. Going},
abstractNote = {Mercury emission compliance presents one of the major potential challenges raised by the 1990 Clean Air Act Amendments. Simple ways of controlling emissions have not been identified. The variability in the field data suggest that inherent mercury emissions may be reduced if the source of this inherent capture can be identified and controlled. The key mechanisms appear to involve the oxidation of mercury to Hg{sup 2}, generally producing the more reactive HgCl{sub 2}, followed by its capture by certain components of the fly ash or char, or in the air pollution control equipment. This research focuses on identifying the rate-limiting steps associated with the oxidation step. Work in this reporting period focused on testing of the kinetic mechanism reported in the previous semiannual report, and the interpretation of data (both ours and literature). This model yields good qualitative agreement with the data and indicates that mercury oxidation occurs during the thermal quench of the combustion gases. The model also suggests that atomic chlorine is the key oxidizing species. The oxidation is limited to a temperature window between 700-400 C that is defined by the overlap of (1) a region of significant superequilibrium Cl concentration, and (2) a region where oxidized mercury is favored by equilibrium. Above 700 C reverse reactions effectively limit oxidized mercury concentrations. Below 400 C, atomic chlorine concentrations are too low to support further oxidation. The implication of these results are that homogeneous oxidation is governed primarily by (1) HCl concentration, (2) quench rate, and (3) background gas composition. Work conducted under the present grant has been the subject of one journal paper that was accepted for publication during the reporting period (Sliger et al., 1999).},
doi = {10.2172/775020},
journal = {},
number = ,
volume = ,
place = {United States},
year = {1999},
month = {8}
}