Ash formation during pulverized coal combustion

Unsworth, John F.; Barratt, David J.; Park, David; Titchener, Keith J.

doi:10.1016/0016-2361(88)90291-8

Cited by 24 publications

(8 citation statements)

References 5 publications

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“…When coal is combusted in pulverized-fuel (pf) boilers to produce electricity, mineral matter in the coal is transformed at elevated temperatures to produce ash and related materials (e.g., slagging and fouling deposits) of varying chemical composition, mineralogy, and physical characteristics (size, shape, viscosity, and density). − While some minerals, such as quartz, may be essentially nonreactive at the temperatures and exposure times associated with combustion, the clay minerals (e.g., kaolinite, illite, and montmorillonite) are reactive phases and usually start to lose water of hydration at temperatures below 500 °C . Carbonates such as calcite, dolomite, and siderite are also reactive, decomposing at temperatures typically between 400 and 1000 °C to liberate CO 2 and produce metal oxide residues (e.g., CaO, MgO, and FeO) .…”

Section: Introductionmentioning

confidence: 99%

“…Low-viscosity ash may adhere to the fire-side surfaces of the boiler tubes and form slag deposits. , Slagging usually refers to the formation of molten deposits in the areas directly exposed to the flame radiation (furnace walls and widely spaced pendant superheaters). ,,,,, Fouling, on the other hand, is the accumulation of ash deposits in the downstream (cooler) convective heat exchange region of the boiler. Ash deposit formation may cause damage to the tubes, block hoppers, and build up layers on the wall that are difficult to clear by soot-blowing. , …”

Section: Introductionmentioning

confidence: 99%

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Mineralogy of Furnace Deposits Produced by South African Coals during Pulverized-Fuel Combustion Tests

Matjie

Ward

et al. 2015

Energy Fuels

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Pilot-scale combustion tests were carried out on coals with low (13.5%) and high (39.6%) ash percentages from the Highveld Coalfield of South Africa, using the ALS-ACIRL 100−200 kW Combustion Test Facility. The mineral matter in the feed coals and also the chemistry and mineralogy of the ash deposits from different parts of the test furnace were analyzed using quantitative X-ray diffraction and X-ray fluorescence techniques, and the results were used to develop an understanding of the mineralogical processes taking place in the different parts of the pulverized-fuel combustion system. Low-temperature oxygenplasma ashing and quantitative X-ray diffractometry showed that the mineral matter of both coals contained abundant kaolinite, lesser but still very significant proportions of quartz and carbonates (ankerite and calcite), and minor proportions of pyrite and other minerals. A small but significant proportion of nonmineral Ca also occurs in the organic matter, especially of the low-ash coal. The chemical composition of the combustion products taken from the different sampling points in the test facility (slagging panels, furnace ash, and fouling probes, etc.) was overall very similar for each coal sample. However, the percentages of the different crystalline minerals in the combustion products showed a wide range of variation at the different sampling points. Anorthite, derived from interaction between Ca and the aluminosilicate components, was formed from both coals at temperatures above 1300 °C, mostly as part of sintered aggregates that built up and became detached from the slagging panel in the highest temperature part of the combustion system. Anhydrite was formed by interaction of Ca with SO 2 ; lime and periclase were also formed from the low-ash coal, where insufficient sulfur was available for complete sulfate development.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Mineralogy of Furnace Deposits Produced by South African Coals during Pulverized-Fuel Combustion Tests

Matjie

Ward

et al. 2015

Energy Fuels

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“…At pre-protector, the deposit was high in KCl and slight less CaSO 4 as compared to the 3 rd superheater. The deposits also contained sorosilicate gehlenite (Ca 2 Al(AlSiO 7 )) which possibly comes from the solid-state reaction of CaO with Al 2 O 3 and SiO 2 at high temperatures 36 . The deposits on the pre-protector contained large content of calcium carbonate, calcium sulfate, silicon tetrachloride as well as alkali chlorides (KCl and NaCl).…”

Section: Resultsmentioning

confidence: 99%

Full-scale experimental investigation of deposition and corrosion of pre-protector and 3rd superheater in a waste incineration plant

Wenga

Zhang

et al. 2017

Sci Rep

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Municipal solid waste (MSW) incineration is widely adopted as a waste management strategy and for the energy production. However, this technology experience grave deposition and corrosion of the boiler tubes due to high chlorine (~1.09wt.%) and alkali metal (Na, K) content in MSW. Little is known about the concentration profile of these corrosive elements in the deposits at different boiler locations. Therefore, a full-scale experimental investigation was conducted to determine the concentration profile of Cl, K, Na, S, and Ca in the deposits at pre-protector and compare with those at 3rd superheater during MSW combustion at a 36 MWe waste incineration plant (WIP) in Chengdu, China. The deposit samples were analyzed using wet chemical techniques, scanning electron microscope coupled with energy dispersive spectroscopy (SEM/EDS), and X-ray diffraction (XRD). The concentrations of Na, K, and Cl were high in the deposits at pre-protector while S and Ca concentrations were high on the 3rd superheater. The pre-protector was severely corroded than the 3rd superheater. The governing mechanisms for the deposition and corrosion on these boiler locations were elucidated.

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“…Table 5 contains the results of X-ray fluorescence analysis on that ash which confirms that silicon, aluminum, iron and calcium seem to be the major elements present, aithough the form of those elements is not so certain. Abrief review of the literature on coal ash mineralogy (Mitchell and Gluskoter, 1976;Tsai, 1982;Jones, _t al., 1985;Wilson, et al, 1986;Unsworth, et al, 1987;Unsworth, et al, 1988) indicates that silicon is most likely present in quartz. Aluminum might be present as alumina, but is more likely to be found with silicon in aluminosilicate compounds.…”

Section: B Analysis Of Ash Contaminantmentioning

confidence: 99%

Wear mechanism and wear prevention in coal-fueled diesel engines. Task 3, Traditional approaches to wear prevention

Schwalb¹

1991

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Ash formation during pulverized coal combustion

Cited by 24 publications

References 5 publications

Mineralogy of Furnace Deposits Produced by South African Coals during Pulverized-Fuel Combustion Tests

Mineralogy of Furnace Deposits Produced by South African Coals during Pulverized-Fuel Combustion Tests

Full-scale experimental investigation of deposition and corrosion of pre-protector and 3rd superheater in a waste incineration plant

Wear mechanism and wear prevention in coal-fueled diesel engines. Task 3, Traditional approaches to wear prevention

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