Fine ash formation during combustion of pulverised coal–coal property impacts

Buhre, B.J.P.; Hinkley, Jim; Gupta, Rajender; Nelson, Peter F.; Wall, Terry

doi:10.1016/j.fuel.2005.04.031

Cited by 123 publications

(106 citation statements)

References 15 publications

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“…Quann and Sarofim, 1986). They may also be responsible for evolution of corrosive and polluting gases such as hydrogen sulphide, carbonyl sulphide, and sulphur oxides (Ozum et al, 1993), and the formation of ultrafine ash particles, as well as condensed metallic vapours, during coal combustion and carbon conversion processes (Zhang et al, 2006;Buhre et al, 2006;Matjie, 2008). Recognition of such elements, through either electron microprobe analysis or more conventional studies, may help to minimize the potential for corrosion, slagging, and fouling in operating combustion and gasification plants (Creelman et al, 2013), as well as the emission of gases and/or fine particulates with potential for adverse environmental impacts.…”

Section: Determination Of Mineral Matter and Elemental Composition Ofmentioning

confidence: 99%

Determination of mineral matter and elemental composition of individual macerals in coals from Highveld mines

Matjie¹,

Li²,

Ward³

et al. 2016

J. S. Afr. Inst. Min. Metall.

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Section: Determination Of Mineral Matter and Elemental Composition Ofmentioning

confidence: 99%

Determination of mineral matter and elemental composition of individual macerals in coals from Highveld mines

Matjie¹,

Li²,

Ward³

et al. 2016

J. S. Afr. Inst. Min. Metall.

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“…Seames [31] and Buhre et al [32] have shown that the PM1 ultra fine fraction of fly-ashes -measuring less than 1 µm diameter -represents less than 1 wt % of the total amount of ashes generated by the coal combustion. Yet the TEM analysis we conducted reveals the presence of a large amount of nano-sized fly-ashes covering the ablated gypsum particles.…”

Section: Discussionmentioning

confidence: 99%

Laser yellowing effect: study of the nanophases created by laser irradiation of synthetic black crusts using transmission electron microscopy (TEM) and electron paramagnetic resonance (EPR) spectroscopy

Godet¹,

Vergès‐Belmin²,

Saheb³

et al. 2017

Proceedings of the International Conference LACONA XI

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Nd:YAG Q-Switched laser cleaning at 1064 nm can sometimes lead to a more yellow appearance of the stone surface in comparison with other cleaning techniques. The yellow hue can originate from different contributions among which the presence of nano-sized residues generated by the laser interaction with the surface materials to be eliminated. In this study, the nature of such residues has been investigated. The analyzed materials are (i) particles collected from a pure gypsum reference plate; (ii) a synthetic crust, composed of 80 wt % natural black crust and 20 wt % synthetic gypsum; (iii) particles ejected from the synthetic crust during laser irradiation. Optical, scanning electron and transmission electron microscopies were used to link color changes at the macro-scale to morphology changes at the submicron-and nano-scales. Chemical composition was also obtained at the nano-scale using TEM coupled with energy dispersive X-ray (EDX) spectroscopy. This multi-scale approach was combined with electron paramagnetic resonance spectroscopy (EPR) analysis at low and room temperatures to examine the possible presence of iron-containing species presenting particular magnetic properties in the sample before and after irradiation. Under laser irradiation, both the crust sample and the ejected gypsum particles take a yellow color. This color shift can be linked with morphology changes occurring at the nano-scale: gypsum crystals from the reference plate show a smooth surface, while those coming from the synthetic black crust are, after irradiation, covered by many spherical nanoparticles and a rough nano-layer ranging from less than 20 nm to more than 100 64Marie Godet et al.nm. TEM-EDX analysis reveals that the two types of nanostructures have a chemical composition very similar to that of iron-rich coal fly-ashes called magnetospheres or ferrospheres. It is suggested that laser irradiation induces a transformation of micrometric size fly-ashes present in the black crust into different types of nanostructures having a chemical composition similar to the one of ferrospheres. EPR analysis demonstrates the presence of ferri-ferro-superparamagnetic species both before and after irradiation, thus indicating that nanosized magnetic iron compounds probably corresponding to magnetite or maghemite oxides are present in the black crust, most probably crystallized on the surface or within the fly-ashes microparticles. This study brings to light the contribution of fly-ashes to the laser induced yellowing process.

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“…16,[23][24][25][26][27] The size distribution is often a strong function of the conditions, coal sizes and coal types. It could range from sizes greater than 30 microns to submicron.…”

Section: C 2015 American Institute Of Chemical Engineersmentioning

confidence: 99%

“…Several papers [22][23][24] in the literature have shown, using scanning electron microscopy (SEM), the existence of liquid slag droplets on the char surface but there is hardly any work that has modeled this phenomenon.…”

Section: Introductionmentioning

confidence: 99%

Development of a hybrid shrinking‐core shrinking‐particle model for entrained‐flow gasifiers

et al. 2015

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in Wiley Online Library (wileyonlinelibrary.com) Slagging entrained-flow gasifiers operate above the melting temperature of the ash. As slag is highly nonwetting on the surface of char (carbon) particles, it is likely that it will agglomerate into one or several slag droplets and some of these droplets can detach from the char particles. If the slag exists in the form of droplets on the char surface rather than as a solid shell around the unreacted char particle, a shrinking particle model would be more physically realistic representation in comparison to the widely used shrinking core model (SCM). In the early section of the gasifier, the temperature remains below the ash melting temperature and, therefore, the SCM is more appropriate in this region. With this motivation, a novel hybrid shrinking-core shrinking-particle model has been developed. The model provides spatial profile of a number of important variables that are not available from the traditional SCM.

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Fine ash formation during combustion of pulverised coal–coal property impacts

Cited by 123 publications

References 15 publications

Determination of mineral matter and elemental composition of individual macerals in coals from Highveld mines

Determination of mineral matter and elemental composition of individual macerals in coals from Highveld mines

Laser yellowing effect: study of the nanophases created by laser irradiation of synthetic black crusts using transmission electron microscopy (TEM) and electron paramagnetic resonance (EPR) spectroscopy

Development of a hybrid shrinking‐core shrinking‐particle model for entrained‐flow gasifiers

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