[PDF] Toxic Substances From Coal Combustion A Comprehensive Assessment eBook

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Page : 114 pages
File Size : 21,26 MB
Release : 1999
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The Clean Air Act Amendments of 1990 identify a number of hazardous air pollutants (HAPs) as candidates for regulation. Should regulations be imposed on HAP emissions from coal-fired power plants, a sound understanding of the fundamental principles controlling the formation and partitioning of toxic species during coal combustion will be needed. With support from the Federal Energy Technology Center (FETC), the Electric Power Research Institute, and VTT (Finland), Physical Sciences Inc. (PSI) has teamed with researchers from USGS, MIT, the University of Arizona (UA), the University of Kentucky (UK), the University of Connecticut (UC), the University of Utah (UU) and the University of North Dakota Energy and Environmental Research Center (EERC) to develop a broadly applicable emissions model useful to regulators and utility planners. The new Toxics Partitioning Engineering Model (ToPEM) will be applicable to all combustion conditions including new fuels and coal blends, low-NOx combustion systems, and new power generation plants. Development of ToPEM will be based on PSI's existing Engineering Model for Ash Formation (EMAF). This report covers the period from 1 April 1999 to 30 June 1999. During this quarter low temperature ashing and elemental analysis of the three Phase II coals were completed. Results from MIT and USGS are comparable. Plans were made for measurements of loss of trace elements during devolatilization and for single particle combustion studies at the University of Utah. The iodated charcoal trap was tested on coal combustion flue gas and was shown to collect both Hg and Se in from the vapor phase with 100% efficiency. Data from the University of Arizona self-sustained combustor were analyzed from the combustion of three coals: Ohio, Wyodak and Illinois No. 6. Ash size distributions and enrichment factors for selected trace elements were calculated. The correlation between the concentration of the more volatile trace elements in the ash and the concentration of major elements such as calcium and aluminum was also examined. Work continued at the University of Utah toward the measurement of chlorine speciation in flue gas. The flat flame burner system for the study of mercury chemistry is nearly complete at the University of Connecticut. XAFS analysis by the University of Kentucky indicated that vapor phase HgCl2 was adsorbed by char samples as HgCl2 (i.e., physisorption), whereas vapor phase Hg0 must react (chemisorption) with species on the char surface to form a chemical complex. Hg-laden and desorbed fly-ash samples obtained from a power plant were separated into carbon-rich and carbon-poor fractions by triboelectrostatic separation.

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Page : 81 pages
File Size : 13,97 MB
Release : 2002
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This study reports on the second phase (Phase II) of USGS research activities in support of DOE contract DE-AC22-95PC95101 ''Toxic Substances From Coal Combustion--A Comprehensive Assessment'', funded under DOE Interagency Agreement DE-AI22-95PC95145. The purpose of the study was to provide a quantitative and semi-quantitative characterization of the modes of occurrence of trace elements in coal samples investigated under Phase II, including (1) Ohio 5/6/7, an Ohio bituminous coal sample blended from the No. 5, No. 6, and No. 7 beds; (2) North Dakota, a lignite sample from the Falkirk Mine, Underwood, ND, and (3) Wyodak, a sub-bituminous coal sample from the Cordero Mine, Gillette, WY. Samples from these coal beds were selected for their range in rank and commercial applicability. Results of this research provide basic information on the distribution of elements in Phase II coal samples, information needed for development of a commercial predictive model for trace-element behavior during coal combustion.

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Page : 34 pages
File Size : 34,46 MB
Release : 1996
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Before electric utilities can plan or implement emissions minimization strategies for hazardous pollutants, they must have an accurate and site-specific means of predicting emissions in all effluent streams for the broad range of fuels and operating conditions commonly utilized. Development of a broadly applicable emissions model useful to utility planners first requires a sound understanding of the fundamental principles controlling the formation and partitioning of toxic species during coal combustion (specifically in Phase I, As, Se, Cr, and possibly Hg). PSI Technologies (PSIT) and its team members will achieve this objective through the development of an {open_quotes}Engineering Model{close_quotes} that accurately predicts the formation and partitioning of toxic species as a result of coal combustion. The {open_quotes}Toxics Partitioning Engineering Model{close_quotes} (ToPEM) will be applicable to all conditions including new fuels or blends, low-NO(subscript x) combustion systems, and new power systems being advanced by DOE in the Combustion 2000 program. This report describes the mineralogy and chemical analysis of bituminous coal samples.

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Page : 39 pages
File Size : 49,65 MB
Release : 1996
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The technical objectives of this project are: to identify the effect of the mode-of-occurrence of toxic elements in coal on the partitioning of these elements among vapor, submicron fume, and fly ash during the combustion of pulverized coal; to identify the mechanisms governing the post-vaporization interaction of toxic elements and major minerals or unburnt char; to determine the effect of combustion environment (i.e., fuel rich or fuel lean) on the partitioning of trace elements between vapor, submicron fume, and fly ash during the combustion of pulverized coal; to model the partitioning of toxic elements between various chemical species in the vapor phase and between the vapor phase and complex aluminosilicate melts; and to develop a frame work for incorporating the results of the program into the Engineering Model for Ash Formation (EMAF). A description of the work plan for accomplishing these objectives is presented in Section 2 of this report. In Section 3 of this report the authors define a detailed list of deliverables expected and consists of a group by group breakdown of the critical experiments to be performed, and a discussion of how that data fits into the overall program. In Section 4 the four coals selected for this program are reported. In Section 5 preliminary XAFs analysis by UKy personnel is discussed. Section 6 consists of a discussion of trace element analysis (INAA) of two size fractions of the Elkhorn-Hazard coal. A discussion of the modifications to the U. Arizona self-sustained combustor is presented in Section 7. Modifications included addition of a baghouse and improvements in the on-line safety and analytical systems. In Section 8 a detailed QA/QC protocol is presented.

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Page : 19 pages
File Size : 30,23 MB
Release : 1996
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The overall objective of this project is to provide analytical support for the Physical Sciences, Inc. (PSI) effort being performed under DOE Contract No. DE-AC22-95101 and entitled '' Toxic Substances from Coal Combustion - A Comprehensive Assessment''. The Pittsburgh Elkhorn/Hazard, and Illinois No. 6 program coals have been examined to determine the mode of occurrence of selected trace elements using scanning electron microscopy, microprobe analysis, and experimental leaching procedures. Preliminary microprobe data indicates that the arsenic content of pyrite grains in the Illinois No. 6 (0.0-0.027 ppm As) and Pittsburgh (0.0-0.080 ppm As) coals is similar. Pyrite grains observed in the Elkhorn/Hazard coal generally have arsenic concentrations (0.0-0.272 wt. %As) that are slightly higher than those of the Pittsburgh or Illinois No. 6 coals. One pyrite grain observed in the Elkhorn/Hazard coal contained much higher levels of arsenic (approximately 2 wt. % As). Preliminary microprobe analyses and data from leaching experiments indicate the association of arsenic with pyrite in the Pittsburgh and Illinois No. 6 coals. Leaching data for arsenic in the Elkhorn/Hazard coal, in contrast, is inconclusive and additional data are needed before a definite determination can be made.

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Page : 15 pages
File Size : 10,66 MB
Release : 1999
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Detailed information on trace-element modes of occurrence in coal is essential to understanding and predicting trace-element transformations taking place during coal combustion. The USGS has developed quantitative and semi-quantitative methods for determining the mode of occurrence of trace elements in coal. This information is needed to generate predictive models for trace-element behavior, the ultimate goal of DOE contract DE-AC22-95PC95101 ''Toxic Substances From Coal Combustion--A Comprehensive Assessment'' awarded to PSI, Inc. USGS activities in support of this contract have a direct bearing on the predictive equations being developed as the primary product of the PSI program.