Behavior of basic elements during coal combustion

Huffman, G.P.; Huggins, Frank E.; Shah, Naresh; Shah, Amber M.

doi:10.1016/0360-1285(90)90033-y

Cited by 85 publications

(72 citation statements)

References 13 publications

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“…There is a need for models of predicting the formation and characteristics of coal-biomass ash mixtures under different gasification conditions. The formation, behavior, and use of ash under combustion conditions for coal [88,263,264], biomass [263,[265][266][267][268] and coal-biomass (co-firing) [101,263,[269][270][271][272][273] is abundant whereas very few are available for coal-biomass co-gasification. The thermochemistry in the two environments is not the same, e.g., gasification ashes have a high content of unburned carbon preventing its direct utilization in some applications where combustion ashes are used.…”

Section: Discussionmentioning

confidence: 99%

“…metals as catalysts for coal gasification have been extensively investigated [84][85][86][87], given the high content of these elements in some biomass, co-gasification of coal and biomass is expected to exhibit some catalytic behavior, whose significance will depend on the type of biomass and coal being used. In fact, Na is the principal alkali metal in lignite (low rank coal) and is said to be bonded to the oxygen anions in the carboxyl groups, while the amount of K is low [88]. In bituminous coals (high rank), K is said to be contained exclusively in illite or closely related clay structure [89], while Na is generally present as NaCl, usually as solution in moisture adsorbed in coal pores and capillaries [90].…”

Section: Devolatilization/pyrolysismentioning

confidence: 99%

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A Review of Thermal Co-Conversion of Coal and Biomass/Waste

2014

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Abstract:Biomass is relatively cleaner than coal and is the only renewable carbon resource that can be directly converted into fuel. Biomass can significantly contribute to the world's energy needs if harnessed sustainably. However, there are also problems associated with the thermal conversion of biomass. This paper investigates and discusses issues associated with the thermal conversion of coal and biomass as a blend. Most notable topics reviewed are slagging and fouling caused by the relatively reactive alkali and alkaline earth compounds (K 2 O, Na 2 O and CaO) found in biomass ash. The alkali and alkaline earth metals (AAEM) present and dispersed in biomass fuels induce catalytic activity during co-conversion with coal. The catalytic activity is most noticeable when blended with high rank coals. The synergy during co-conversion is still controversial although it has been theorized that biomass acts like a hydrogen donor in liquefaction. Published literature also shows that coal and biomass exhibit different mechanisms, depending on the operating conditions, for the formation of nitrogen (N) and sulfur species. Utilization aspects of fly ash from blending coal and biomass are discussed. Recommendations are made on pretreatment options to increase the energy density of biomass fuels through pelletization, torrefaction and flash pyrolysis to reduce transportation costs.

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Section: Discussionmentioning

confidence: 99%

Section: Devolatilization/pyrolysismentioning

confidence: 99%

A Review of Thermal Co-Conversion of Coal and Biomass/Waste

2014

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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

1,022

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 content of quartz (5.8%) in the fly ash is much lower than that in the feed coal (18.8%, on ash basis), which indicates that quartz, at least partially, melted during the coal combustion at around 1400 °C. FeS2 (pyrite), CaO (calcite) and some alkali metals (e.g., K and Na) in coal are likely to react with the clay, quartz and other minerals in coal to form a low-temperature eutectic mixture [47,48], which can melt at a temperature much lower than the melting points of single minerals (e.g., 1750 °C of quartz). Anatase (melting point of 1850 °C) existing in feed coal is not detected in the fly ash, which can be attributed to the same reason.…”

Section: Morphology and Composition Of Microspheres In The Fly Ashmentioning

confidence: 99%

Morphology and Composition of Microspheres in Fly Ash from the Luohuang Power Plant, Chongqing, Southwestern China

et al. 2016

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Abstract:In order to effectively raise both utilization rate and additional value of fly ash, X-Ray diffraction (XRD), scanning electron microscope (SEM) and energy-dispersive X-Ray spectrometer (EDS) were used to investigate the morphology, and chemical and mineral composition of the microspheres in fly ash from the Luohuang coal-fired power plant, Chongqing, southwestern China. The majority of fly ash particles are various types of microspheres, including porous microsphere, plerospheres (hollow microspheres surrounding sub-microspheres or mineral fragments) and magnetic ferrospheres. Maghemite (γ-Fe 2 O 3 ) crystals with spinel octahedron structure regularly distribute on the surfaces of ferrospheres, which explained the source of their strong magnetism that would facilitate the separation and classification of these magnetic ferrospheres from the fly ash. Microspheres in Luohuang fly ash generally are characterized by an elemental transition through their cross-section: the inner layer consists of Si and O; the chemical component of the middle layer is Si, Al, Fe, Ti, Ca and O; and the Fe-O mass (maghemite or hematite) composes the outer layer (ferrosphere). Studies on composition and morphological characteristics of microspheres in fly ash would provide important information on the utilization of fly ash, especially in the field of materials.

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Behavior of basic elements during coal combustion

Cited by 85 publications

References 13 publications

A Review of Thermal Co-Conversion of Coal and Biomass/Waste

A Review of Thermal Co-Conversion of Coal and Biomass/Waste

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

Morphology and Composition of Microspheres in Fly Ash from the Luohuang Power Plant, Chongqing, Southwestern China

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