Rheological evolution and crystallization response of molten coal ash slag at high temperatures

Song, Wenjia; Tang, Lihua; Zhu, Zhaojie; Ninomiya, Yoshihiko

doi:10.1002/aic.14052

Cited by 24 publications

(15 citation statements)

References 59 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[19] Another reason of the shear thinning in silicate systems is the disruption of aggregates or the solid network. As reported in literature, with increasing solid fraction, solid aggregates or an internal network can form [10,23,68,69,76] . Due to the weak attraction force between particles, the aggregates or network can be broken up into isolated particles when subjected to an increasing shear rate.…”

Section: Shear-dependent Behaviorsupporting

confidence: 58%

Viscosity of Heterogeneous Silicate Melts: A Review

Liu

Pandelaers

Blanpain

et al. 2018

Metall Mater Trans B

View full text Add to dashboard Cite

The viscosity of solid phase containing heterogeneous silicate melts is discussed in this review. The crucial parameters characterizing silicate melt structure are first presented, i.e. volume fraction of solid particles, particle shape and size. The measurement and calculation methods of these parameters are summarized and the influence of the parameters on viscosity is discussed. Next, a theoretical description of rheological behavior in heterogeneous silicate melts is given, focusing on non-Newtonian characteristics, e.g. shear-dependence, timedependence, and yield stress. The viscosity models which were proposed in the last half century are reviewed and critically assessed. This paper concludes with opportunities and suggestions for future work.

show abstract

Section: Shear-dependent Behaviorsupporting

confidence: 58%

Viscosity of Heterogeneous Silicate Melts: A Review

Liu

Pandelaers

Blanpain

et al. 2018

Metall Mater Trans B

View full text Add to dashboard Cite

show abstract

“…Slag samples were quenched periodically and removed for study using SEM analysis. They noted changes in molten slag viscosity as a function of temperature and crystal size distribution, and reported that transition from Newtonian to non-Newtonian flow occurs around 5% (volume/volume) solid phase content in the slag [52].…”

Section: High-temperature Rotary Viscometrymentioning

confidence: 98%

“…Mueller et al investigated the effect of particle shape on the effective viscosity using model particles suspended in silicone oil, and found that particle jamming effects can be described by R [51]. Song et al note that the Einstein-Roscoe model does not account for shear rate dependence, and proposed the use of a modified semi-empirical model that incorporates high-and low-shear rate viscosity values instead [52].…”

Section: Viscosity Of Subliquidus Molten Silicatesmentioning

confidence: 98%

“…For example, FactSage, an integrated software package that combines thermochemical databases with Gibbs energy minimization software [119,120], is widely used to calculate chemical equilibria in slag systems. It has been used to predict the formation of solid phases in basic oxygen furnace slag [50], estimate coal ash fusion temperatures [121], model the effect of solid phase formation on viscosity in coal ash slags [52,85,111,112,114,[122][123][124] and petroleum coke-coal blend slags [125], and assess the effect of additives on coal ash slag viscosity [15,126]. MTDATA is another CALPHAD-based software tool that has been used to estimate coal fusibility [127] and ash fusion temperatures [128].…”

Section: Thermophysical Modeling Of Coal Ash Slagsmentioning

confidence: 99%

See 1 more Smart Citation

Correlation between the critical viscosity and ash fusion temperatures of coal gasifier ashes

Hsieh

Kwong

Bennett

2016

Fuel Processing Technology

View full text Add to dashboard Cite

Coal gasification yields synthesis gas, an important intermediate in chemical manufacturing. It is also vital to the production of liquid fuels through the Fischer-Tropsch process and electricity in Integrated Gasification Combined Cycle power generation. Minerals naturally present in coal become molten in entrained-flow slagging gasifiers. Molten coal ash slag penetrates and dissolves refractory bricks, leading to costly plant shutdowns. The extent of coal ash slag penetration and refractory brick dissolution depends on the slag viscosity, the gasification temperature, and the composition of slag and bricks. We measured the viscosity of several synthetic coal ash slags with a high-temperature rotary viscometer and their ash fusion temperatures through optical image analysis. All measurements were made in a carbon monoxide-carbon dioxide reducing atmosphere that approximates coal gasification conditions. Empirical correlation models based on ash fusion temperatures were used to calculate critical viscosity temperatures based on the coal ash compositions. These values were then compared with those obtained from thermodynamic phase-transition models. An understanding of slag viscosity as a function of ash composition is important to reducing refractory wear in slagging coal gasifiers, which would help to reduce the cost and environmental impact of coal for chemical and electricity production.Published by Elsevier B.V.

show abstract

“…(1) Disruption of aggregates or solid network According to this theory, the connections between crystals inside aggregates and solid network are weak and can be gradually broken up into isolated particles when the slag is subjected to a sufficient shear rate [7,[10][11][12][13] . Because of the wholly or partially disrupted microstructure, the obstruction exerted on the rotational spindle reduces, leading to a viscosity decrease.…”

Section: Shear-dependent Behaviormentioning

confidence: 99%

Non-Newtonian behavior of solid-bearing silicate melts: An experimental study

Liu

Zhang

Malfliet

et al. 2018

Journal of Non-Crystalline Solids

View full text Add to dashboard Cite

The non-Newtonian behavior and its mechanism have not been clarified for the solid-bearing metallurgical slags, leading to difficulties in the modeling of viscosity. In this study, the viscosity of an industrial BOF slag with different contents of Al2O3 was measured via a rotational type rheometer at various shear rates. The crystal fraction was examined by characterizing the water-quenched samples.The results demonstrate that the slags exhibit non-Newtonian behavior for solid fractions exceeding a critical value (Φc, i.e. 0.33-0.40 for the investigated samples), at which an abrupt viscosity increase occurs. Shear thinning (the viscosity decreases with increasing shear rate), thixotropy (a time-dependent shear thinning) and an apparent yield stress of 0.21-74.43 Pa for the investigated samples are the non-Newtonian characteristics observed in this study. The higher the solid fraction, the more pronounced the shear thinning. The shear thinning is mainly attributed to the disruption of crystal clusters.Thixotropic behavior is found to be caused by the irreversible microstructural evolution within the experimental time scale. The apparent yield stress is mainly due to the formation of a solid network and is increased with increasing the solid fraction.

show abstract

Rheological evolution and crystallization response of molten coal ash slag at high temperatures

Cited by 24 publications

References 59 publications

Viscosity of Heterogeneous Silicate Melts: A Review

Viscosity of Heterogeneous Silicate Melts: A Review

Correlation between the critical viscosity and ash fusion temperatures of coal gasifier ashes

Non-Newtonian behavior of solid-bearing silicate melts: An experimental study

Contact Info

Product

Resources

About