Fate of Selenium in Coal Combustion:  Volatilization and Speciation in the Flue Gas

Yan, Rong; Gauthier, Daniel J.; Flamant, Gilles; Péraudeau, G.; Lü, Jidong; Chen, Zheng

doi:10.1021/es0001005

Cited by 81 publications

(47 citation statements)

References 11 publications

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“…The enrichment of selenium in the diluted PM 2.5 sample is not unexpected, as selenium is present in the gas phase at stack conditions (Germani and Zoller 1988;Galbreath et al 2000;Yan et al 2001). Selenium enrichment has been observed in Figure 1.…”

Section: Dilution and Pm 25 Compositionmentioning

confidence: 60%

Effects of Dilution Sampling on Fine Particle Emissions from Pulverized Coal Combustion

Lipsky

Pekney

Walbert

et al. 2004

Aerosol Science and Technology

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A dilution sampler was used to examine the effects of dilution ratio and residence time on fine-particle emissions from a pilot-scale pulverized coal combustor. Measurements include the particle size distribution from 0.003 to 2.5 µm, PM 2.5 mass, and PM 2.5 composition (OC/EC, major ions, and elemental). Heated filter samples were also collected simultaneously at stack temperatures in order to compare the dilution sampler measurements with standard stack sampling methodologies. Measurements were made both before and after the bag house, the particle control device used on the coal combustor, and while firing three different coal types and one coalbiomass blend. The PM 2.5 mass emission rates measured using the dilution sampler agreed to within experimental uncertainty with those measured with the hot-filter sampler. Relative to the heated filter sample, dilution did increase the PM 2.5 mass fraction of selenium for all fuels tested, as well as ammonium and sulfate for selected fuels. However, the additional particulate mass created by gas-to-particle conversion of these species is within the uncertainty of the gravimetric analysis used to determine the overall mass emission rate. The enrichment of PM 2.5 selenium caused by dilution did not vary with dilution ratio and residence time. The enrichment of PM 2.5 sulfate and ammonium varied with fuel composition and dilution ratio but not residence time. For example, ammonium was only enriched in diluted acidic aerosol samples. A comparison of the PM 2.5 emission profiles for each of the fuels tested underscores how differences in PM 2.5 composition are related to the fuel ash composition. When sampling after the bag house, the particle size distribution and total particle number emission rate did not depend on residence time and dilution ratio because of the much lower particle number concentrations in diluted sample and the absence of nucleation. These results provide new insight into the effects Address correspondence to Allen Robinson, Department of Mechanical Engineering, Carnegie Mellon University, 5000 Forbes Ave., Pittsburgh, PA 15213, USA. E-mail: alr@andrew.cmu.edu of dilution sampling on measurements of fine particle emissions, providing important data for the ongoing effort of the EPA and ASTM to define a standardized dilution sampling methodology for characterizing emissions from stationary combustion sources.

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Section: Dilution and Pm 25 Compositionmentioning

confidence: 60%

Effects of Dilution Sampling on Fine Particle Emissions from Pulverized Coal Combustion

Lipsky

Pekney

Walbert

et al. 2004

Aerosol Science and Technology

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“…Coal combustion is thought to be the main selenium releasing anthropogenic process, being responsible of about 7,300 tons of selenium per year (Yudovich and Ketris 2006). Selenium is one of the most volatile trace elements in coal, and is largely released in vapor phase to the atmosphere, mainly as the SeO 2 (g), SeO(g) and solid selenium species (Yan et al 2001). Haygarth et al (1994), demonstrated from selenium herbage historical data a positive correlation between the highest concentrations found in 1940 and 1970 with the high coal combustion activity observed in these years.…”

Section: Anthropogenic Sourcesmentioning

confidence: 99%

Selenium environmental cycling and bioavailability: a structural chemist point of view

Fernández-Martı́nez

Charlet

2009

Rev Environ Sci Biotechnol

390

235

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International audienceSelenium is usually known as the ‘double-edged sword element' for its dual toxic and beneficial character to health. Since the pioneer works by Schwarz and Foltz on the relationships between selenium deficiency and liver, muscle and heart diseases, many efforts have been undertaken to better understand the role of selenium in health. At the same time, an increasing number of publications have appeared during these last years on the selenium physico–chemical interactions within the environment. Both types of research represent ongoing efforts to correctly estimate the bioavailability of selenium species for health and the environment. Redox reactions, diffusion, adsorption and precipitation processes or interactions with organic matter and biota govern the speciation and mobility of selenium in the environment. This review intends to emphasize and collect the important advances made during these last years in the mechanistic understanding of processes which govern selenium cycling and bioavailability, like adsorption at the mineral/water interface, precipitation of elemental selenium, or bioavailability of nanoscaled precipitates. The advent of powerful spectroscopic techniques, like X-ray absorption spectroscopy, has allowed the structural description of adsorption and substitution processes that selenium undergoes in a variety of minerals. These and other structural details about selenium precipitates are reviewed here, together with their relationships to the bioavailability of the element in the environment

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“…Selenium shows the greatest enrichment, with levels in the diluted sampling being as much as a factor of 12 than in the hot filters. The enrichment of selenium is not unexpected as it is known to be in the gas phase at stack conditions (Germani and Zoller 1988;Galbreath, Toman et al 2000;Yan, Gauthier et al 2001). In addition, enrichment of selenium has been observed in the plume downwind of a coal-fired power plant (Ondov et al 1989).…”

Section: Size Distributionsmentioning

confidence: 84%

Sampling, Analysis, and Properties of Primary PM-2.5: Application to Coal-Fired Utility Boilers

Robinson

Pandis²,

Lipsky³

et al. 2003

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A dilution sampler was used to examine the effects of dilution ratio and residence time on the particulate emissions from a pilot-scale pulverized coal combustor. Measurements include the particle size distribution from 0.003 to 2.5 µm, PM 2.5 mass emission rate and PM2.5 composition (OC/EC, major ions, and elemental). Hot filter samples were also collected simultaneously in order to compare the dilution sampler measurement with standard stack sampling methodologies such as EPA Method 5. Measurements were made both before and after the bag-house, the particle control device used on the coal combustor. Measurements were made with three different coal types and a coal-biomass blend.The residence time and dilution ratio do not influence the PM 2.5 mass emission rate, but have a significant effect on the size distribution and total number emissions. Measurements made before the bag-house showed increasing the residence time dramatically decreases the total particle number concentration, and shifts the particle mass to larger sizes. The effects of residence time can be explained quantitatively by the coagulation of the emitted particles. Measurements made after the bag-house were not affected by coagulation due to the lower concentration of particles. Nucleation of sulfuric acid vapor within the dilution was an important source of ultrafine particles. This nucleation is strongly a function of dilution ratio because of the competition between condensation and nucleation. At low dilution ratios condensation dominates and little nucleation is observed; increasing the dilution ratio promotes nucleation because of the corresponding decrease in available surface area per unit volume for condensation. No nucleation was observed after the bag house where conditions greatly favor nucleation over condensation; we suspect that the bag house removed the SO 3 in the flue gas. Exhaust SO 3 levels were not measured during these experiments.Dilution caused the enrichment of selenium, ammonium and sulfate in the PM 2.5 emissions compared to the hot filter samples. The enrichment of selenium was independent of dilution ratio or residence time. The enrichment of ammonium and sulfate increased with increasing dilution ratio. PM 2.5 emission profiles for four different fuels (two eastern bituminous coals, a western sub-bituminous coal, and coal-wood blend) were developed. These profiles compared well with profiles from similar coal sources, while showing unique characteristics due to differences in fuel composition. Executive SummaryIn 1997 the US EPA proposed new standards for particulate matter with an aerodynamic diameter less than 2.5 µm (PM 2.5 ). Development of the regulatory framework necessary to meet these new standards requires improved understanding of the sources for PM 2.5 . Coal-fired utility boilers are one important emission source for particulate matter. Utility boilers are a primary source for both fine particles and gaseous precursors such as SO 2 and NO x that react in the atmosphere to create secondary aeros...

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Fate of Selenium in Coal Combustion: Volatilization and Speciation in the Flue Gas

Cited by 81 publications

References 11 publications

Effects of Dilution Sampling on Fine Particle Emissions from Pulverized Coal Combustion

Effects of Dilution Sampling on Fine Particle Emissions from Pulverized Coal Combustion

Selenium environmental cycling and bioavailability: a structural chemist point of view

Sampling, Analysis, and Properties of Primary PM-2.5: Application to Coal-Fired Utility Boilers

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