Ash Formation Mechanisms during pf Combustion in Reducing Conditions

Mclennan, A. R.; Bryant, Glenn; Stanmore, B. R.; Wall, Terry

doi:10.1021/ef990095u

Cited by 118 publications

(69 citation statements)

References 15 publications

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“…This could be explained assuming vaporization and subsequent conden sation of volatile elements (Na, K, S, Cl) on the fine ash particles, as also observed and reported in other publications [23,19]. In [30] it is stated that the size dependent chemical composition of the sub micron ash indicates that the condensation of evaporated species was responsible for the formation of ash particles smaller than 0.3 mm.…”

Section: Chemical Composition Analysis: Element Enrichment Icp Analyssupporting

confidence: 66%

“…Also S is depleted in both the deposit as well as the filter ash, as it is suggested to react with alkalis and therefore enters the gas phase [19]. Under high temperatures and oxidising conditions, essentially all of the sulfur containing inorganic species in coal (primarily sulfates and pyrites) decompose to form SO 2 therefore none of the fuel sulfur passes unreacted through the combustor [27].…”

Section: Chemical Composition Analysis: Element Enrichment Icp Analysmentioning

confidence: 99%

“…Char temperature fluctuations between air and oxy fuel combustion, affect therefore the degree of release of the in cluded minerals and alter their extent of vaporization. Reducing conditions may also have a notable impact on excluded minerals, particularly iron based minerals [19].…”

Section: Introduction and Scope Of Workmentioning

confidence: 99%

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Study on ash deposition under oxyfuel combustion of coal/biomass blends

Fryda

Sobrino

Cieplik

et al. 2010

Fuel

111

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a b s t r a c tCombustion in an O 2 /CO 2 mixture (oxyfuel) has been recognized as a promising technology for CO 2 cap ture as it produces a high CO 2 concentration flue gas. Furthermore, biofuels in general contribute to CO 2 reduction in comparison with fossil fuels as they are considered CO 2 neutral. Ash formation and deposi tion (surface fouling) behavior of coal/biomass blends under O 2 /CO 2 combustion conditions is still not extensively studied. Aim of this work is the comparative study of ash formation and deposition of selected coal/biomass blends under oxyfuel and air conditions in a lab scale pulverized coal combustor (drop tube). The fuels used were Russian and South African coals and their blends with Shea meal (cocoa). A horizontal deposition probe, equipped with thermocouples and heat transfer sensors for on line data acquisition, was placed at a fixed distance from the burner in order to simulate the ash deposition on heat transfer surfaces (e.g. water or steam tubes). Furthermore, a cascade impactor (staged filter) was used to obtain size distributed ash samples including the submicron range at the reactor exit. The deposition ratio and propensity measured for the various experimental conditions were higher in all oxyfuel cases. The SEM/EDS and ICP analyses of the deposit and cascade impactor ash samples indicate K interactions with the alumina silicates and to a smaller extend with Cl, which was all released in the gas phase, in both the oxyfuel and air combustion samples. Sulfur was depleted in both the air or oxyfuel ash deposits. S and K enrichment was detected in the fine ash stages, slightly increased under air combustion conditions. Chemical equilibrium calculations were carried out to facilitate the interpretation of the measured data; the results indicate that temperature dependence and fuels/blends ash composition are the major factors affecting gaseous compounds and ash composition rather than the combustion environment, which seems to affect the fine ash (submicron) ash composition, and the ash deposition mechanisms.

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Section: Chemical Composition Analysis: Element Enrichment Icp Analyssupporting

confidence: 66%

Section: Chemical Composition Analysis: Element Enrichment Icp Analysmentioning

confidence: 99%

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Study on ash deposition under oxyfuel combustion of coal/biomass blends

Fryda

Sobrino

Cieplik

et al. 2010

Fuel

111

View full text Add to dashboard Cite

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“…Iron in an alumino-silicate glass is a characteristic phase found in coal fly ash formed under both oxidizing and reducing conditions. [194][195][196] The presence of large concentrations of alkali and alkali earth elements, typical of western U.S. coals, enhances glass formation and decreases crystallization. …”

Section: Coal-fired Steam Generation Boilersmentioning

confidence: 99%

Combustion Aerosols: Factors Governing Their Size and Composition and Implications to Human Health

Lighty

Veranth

Sarofim

2000

Journal of the Air & Waste Management Association

1,008

600

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Particulate matter (PM) emissions from stationary combustion sources burning coal, fuel oil, biomass, and waste, and PM from internal combustion (IC) engines burning gasoline and diesel, are a significant source of primary particles smaller than 2.5 µm (PM 2.5 ) in urban areas. Combustion-generated particles are generally smaller than geologically produced dust and have unique chemical composition and morphology. The fundamental processes affecting formation of combustion PM and the emission characteristics of important applications are reviewed. Particles containing transition metals, ultrafine particles, and soot are emphasized because these types of particles have been studied extensively, and their emissions are controlled by the fuel composition and the oxidant-temperature-mixing history from the flame to the stack. There is a need for better integration of the combustion, air pollution control, atmospheric chemistry, and inhalation health research communities. Epidemiology has demonstrated that susceptible individuals are being harmed by ambient PM. Particle surface area, number of ultrafine particles, bioavailable transition metals, polycyclic aromatic hydrocarbons (PAH), and other particle-bound organic compounds are suspected to be more important than particle mass in determining the effects of air pollution. Time-and size-resolved PM measurements are needed for testing mechanistic toxicological hypotheses, for characterizing the relationship between combustion operating conditions and transient emissions, and for source apportionment studies to develop air quality plans. Citations are provided to more specialized reviews, and the concluding comments make suggestions for further research.

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“…The metal processing industry and involved plants are another major source of environmental pollution. During the high temperature processes, magnetic spherical particles are usually formed (Sokol et al, 2000;McLennan et al, 2000). Nevertheless, the deposition of these particles on the ground contributes significantly to the magnetic component and heavy metal concentrations in the road dusts near power plants.…”

Section: Tracing Of Contamination Sourcesmentioning

confidence: 99%

Magnetic properties of street dust from Chibi City, Hubei Province, China: Its implications for urban environment

et al. 2009

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Magnetic measurements and heavy metal analyses were performed on street dusts from the main urban area of Chibi (赤壁) City, Hubei (湖北) Province, China. Results revealed that a PSD/MD (pseudo-single-domain/multi-domain) magnetite-like phase dominates the magnetic phases of the street dust. Concentration-related magnetic parameters, such as magnetic susceptibility (χ), anhysteretic remanent magnetization (ARM), and saturation isothermal remanent magnetization (SIRM) of samples increased in the main roads but appeared lower in the landscape area of the Lushui (陆水) Lake and closely correlated with the concentration of heavy metal Fe, Cu, and Co, and the correlation coefficients are 0.786 for Fe-χ, 0.548 for Cu-χ, and 0.580 for Co-χ, respectively. However, much strong correlations between SIRM and the concentrations of heavy metal suggest that SIRM is a better indicator for heavy metal pollution in the street dust in the study area. The magnetic particles in the street dust are mainly derived from anthropogenic activities, such as vehicle emissions, abrasion of tires, coal combustion, cement works, and building materials. These results make it possible to use magnetic techniques as simple, rapid, and nondestructive tools for assessing the heavy metal pollutions in urbanization process. KEY WORDS: environmental magnetism, street dust, heavy metal, Chibi City.

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Ash Formation Mechanisms during pf Combustion in Reducing Conditions

Cited by 118 publications

References 15 publications

Study on ash deposition under oxyfuel combustion of coal/biomass blends

Study on ash deposition under oxyfuel combustion of coal/biomass blends

Combustion Aerosols: Factors Governing Their Size and Composition and Implications to Human Health

Magnetic properties of street dust from Chibi City, Hubei Province, China: Its implications for urban environment

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