Studies of carbonaceous cenospheres from fluidised-bed combustors

Littlejohn, R. F.; Duin, P.J. van

doi:10.1016/0048-9697(84)90272-9

Cited by 9 publications

(3 citation statements)

References 4 publications

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“…The coarse carbonaceous spheres are characterised by a porous surface and many internal cavities. This gives the particles a density much lower than would be expected if calculated from their inorganic composition (Gay et al 1984, Raeymaekers et al 1988. For the same reason these particles have a very large surface area (Raask 1981, Del Monte et al 1984.…”

Section: Introductionmentioning

confidence: 95%

Environmental records of carbonaceous fly-ash particles from fossil-fuel combustion

Wik

Renberg

1996

J Paleolimnol

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Fossil fuel combustion produces fly-ash particles that are released into the atmosphere and deposited in the environment. A particularly characteristic kind of fly-ash is spheroidal carbonaceous particles. They are composed of an amorphous carbon matrix in which other elements are dispersed. The elemental carbon content makes them very resistant to chemical degradation and these particles can be relatively easily extracted from sediment and soil samples using a method described in this thesis. The distribution of spheroidal carbonaceous particles in lake sediment profiles, surface sediments and forest soils has been studied. Cores from several Swedish lakes have been analysed and, although the lakes are from different parts of the country, consistent trends in the deposition of the carbonaceous particles have been found. The analyses of dated cores show that the carbonaceous particle deposition in the sediments follows the same general pattern as statistics for Swedish coal and oil combustion over the last two centuries. This indicates that the sediment records reflect the history of the atmospheric deposition of particulate pollutants from fossil fuel combustion. Analysis of surface sediment samples provides an integrated picture of the deposition over the preceding few years and can be used to indicate the contemporary geographical pattern of deposition from the atmosphere. Two sets of surface sediment samples (0-1 cm) were analysed. One comprised samples from 66 lakes around Sweden's second largest city, Gothenburg, and showed very high carbonaceous particle concentrations within a distance of 50 to 100 km from the city. The second set comprised surface sediment samples from 114 lakes distributed all over Sweden. This survey of Sweden demonstrated a geographical north-south gradient with more than a hundred times higher particle concentrations in the south than in the north. This distribution is similar to the distribution of other air pollutants (data obtained from a moss survey and an air monitoring program) and suggests that carbonaceous particles in palaeolimnological investigations of air pollution, can be used as tracers for pollutants that are otherwise difficult to determine in lake sediments. Spheroidal carbonaceous particles also accumulate in soils, and forest soil samples can be used for geographical surveys of particle deposition. In Swedish podzol soils the particles mainly accumulate in the thin organic horizon and concentrations in this layer reflect the total deposition since industrialisation, although most will have been deposited during the last few decades. Since the spheroidal carbonaceous particle record in Swedish lake sediments has a characteristic temporal pattern, carbonaceous particle profiles can be used for indirect dating of recent sediment cores. Analyses of multiple sediment cores from three lakes demonstrate that carbonaceous particles can also be used for studies of sediment distribution in lake basins. Results from Gårdsjön indicate that the acidification of the lake changed...

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Section: Introductionmentioning

confidence: 95%

Environmental records of carbonaceous fly-ash particles from fossil-fuel combustion

Wik

Renberg

1996

J Paleolimnol

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“…Recent studies suggest that carbonaceous particlescomposed primarily of elemental carbon and associated organic matter-play an important role in the atmospheric transformation of pollutants (3), degradation of atmospheric visibility (4), and the atmospheric greenhouse effect (5). Carbonaceous particles have been identified in electrostatic precipitator hopper ash and stack ash from pulverized coal combustion (1,2, 6-8) and in the flue gas stream from fluidized bed combustion (9).…”

Section: Introductionmentioning

confidence: 99%

Influence of carbonaceous particles on the interaction of coal combustion stack ash with organic matter

Griest¹,

Tomkins²

1986

Environ. Sci. Technol.

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“…These authors concluded the following: high volatile bituminous coal developed tenuispheres and basic anisotropy; medium volatile bituminous coal developed crassispheres and semianthracitic vitrinite cenospheres and sub-angular char; in all cases "non-reactive" inertinite remains unaltered, thus keeping its original morphological identity while "reactive" macerals developed cenospheres and became rounded. [22][23][24][25][26][27][28] From these FBC studies, it could be concluded that, as in pulverized coal combustion, char morphotypes depend on the rank and petrographic composition of coal and, to some degree, follow the same trends with rank and petrographic composition.…”

Section: Introductionmentioning

confidence: 99%

Relation between the Petrographic Composition of Coal and the Morphology of Pyrolysis Char Produced in Fluidized Bed

et al. 2004

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Several previous studies have already established, for pulverized coal combustion conditions, global correlations between petrographic composition of the coal and those of char produced from the same coal. However, for fluidized bed combustion, there has not been much new work since the eighties. The results presented in this paper include the petrographic characterization of seven different coals from several origins and also of their respective chars produced at 700°C, 800°C, 900°C, and 1000°C in a laboratory fluidized bed reactor. The results show a marked predominance of tenuispheres as the trial temperatures increase. While vitrinite-rich coals essentially produced highly porous chars, the inertinite-rich coals produced large amounts of medium-and low-porous chars. Semi-anthracite vitrinite produced high-porous chars and thermal affected coal particles originated low-porous and angular char morphotypes. The analysis of the data obtained revealed that vitrinite + liptinite related well with the high-porous char (sum of cenospheres and tenuinetworks), classified as Group 1. The same trend, but with a weaker relation, was also observed between vitrinite and liptinite rich microlithotypes and Group 1.

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Studies of carbonaceous cenospheres from fluidised-bed combustors

Cited by 9 publications

References 4 publications

Environmental records of carbonaceous fly-ash particles from fossil-fuel combustion

Environmental records of carbonaceous fly-ash particles from fossil-fuel combustion

Influence of carbonaceous particles on the interaction of coal combustion stack ash with organic matter

Relation between the Petrographic Composition of Coal and the Morphology of Pyrolysis Char Produced in Fluidized Bed

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