Viscosity model for oxide melts relevant to fuel slags. Part 2: The system SiO 2 –Al 2 O 3 –CaO–MgO–Na 2 O–K 2 O

Wu, Guixuan; Yazhenskikh, Elena; Hack, Klaus; Müller, Michael

doi:10.1016/j.fuproc.2015.06.031

Cited by 34 publications

(8 citation statements)

References 39 publications

(72 reference statements)

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“…17 However, in our work, we assume that densification occurs by liquid phase sintering because a liquid phase forms at temperatures as low as 1200°C due to the presence of other impurities and dopants such as Na 2 O and MgO, and is present throughout the sintering process. The Al 2 O 3 -SiO 2 -MgO phase diagram suggests that MgO increases the solubility of Al 2 O 3 in the liquid, and MgO can lower the viscosity of the glass melt, 18 which results in higher The second stage at which MgO affects densification is after 1 hour at 1525°C. MgO-free powder samples with 0.22 vol.% glass phase and Na 2 O/SiO 2 ratios of 0.9 have 1%-2% higher relative densities than samples with 0.22 vol.% glass phase and Na 2 O/SiO 2 ratios of 0.1 for all hold times at 1525°C.…”

Section: Sintering and Microstructure Analysismentioning

confidence: 99%

Powder chemistry effects on the sintering of MgO‐doped specialty Al₂O₃

et al. 2018

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In this work, we investigate the effects of powder chemistry on the sintering of MgO‐doped specialty alumina. The stages at which MgO influences densification of Al2O3 were identified by comparing dilatometry measurements and the sintering kinetics of MgO‐free and MgO‐doped specialty alumina powders. MgO is observed to reduce the grain boundary thickness during densification using TEM. We show that MgO increases the solubility of SiO2 in alumina grains near the boundaries using EDS. First‐principles DFT calculations demonstrate that the co‐dissolution of MgO and SiO2 in alumina is thermodynamically favored over the dissolution of MgO or SiO2 individually in alumina. This study experimentally demonstrates for the first time that removal of SiO2 from the grain boundaries is a key process by which MgO enhances the sintering of alumina.

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Section: Sintering and Microstructure Analysismentioning

confidence: 99%

Powder chemistry effects on the sintering of MgO‐doped specialty Al₂O₃

et al. 2018

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“…The viscosity of the slags investigated was calculated using the structure‐based model developed by Wu et al. 25–28, as indicated in Eq. 1.…”

Section: Methodsmentioning

confidence: 99%

“…To describe the complex influence of slag components on the viscosity of biomass slags, the structure‐based model developed by Wu et al. 24–28 was applied in this study.…”

Section: Introductionmentioning

confidence: 99%

Optimization of Slag Mobility of Biomass Fuels in a Pilot‐scale Entrained‐Flow Gasifier

Mielke

Eberhard

et al. 2021

Chem Eng & Technol

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The bioliq® process, developed at the Karlsruhe Institute for Technology, aims at the production of synthetic fuels and chemicals from biomass. The bioliq® technology is based on a two‐step process with decentral pyrolysis for the production of a transportable slurry from residual biomass and the central entrained‐flow gasification of the slurry by using biomass‐to‐liquid technology. This study is focused on the slag, which is formed by melting the inorganic ash components during gasification. To operate the gasifier smoothly, a range of desired viscosity has to be defined. A structure‐based viscosity model was used to predict the viscosity of the slags at the gasifier outlet. A good agreement between experimental and calculated viscosities is achieved for fully liquid slag systems.

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“…The gas-phase was regarded as an ideal gas (perfect mixture), and the following gaseous species were considered: CO 2 , N 2 , O 2 , H 2 O, K, and KOH. The viscosity of the molten fraction of the predicted phases was estimated using the associate-based model previously established by Nentwig et al [41] and Wu et al [42][43][44][45][46]. The experimentally derived viscosity models reported in the literature [47][48][49] are restricted to a specific range of compositions and atmospheres.…”

Section: Thermochemical Equilibrium Calculations (Tecs) and Viscosity Estimationsmentioning

confidence: 99%

The Feasibility of Replacing Coal with Biomass in Iron-Ore Pelletizing Plants with Respect to Melt-Induced Slagging

et al. 2020

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Combustion-generated fly ash particles in combination with the particles arising from the disintegration of iron-ore pellets, could give rise to the build-up of deposits on the refractory linings of the induration facility. Due to climate change and other environmental issues, there is a desire to cut down on use of fossil fuels. Therefore, it is of interest to investigate the feasibility of replacing coal with less carbon-intensive alternatives such as upgraded biomass, e.g., biochar and pyrolysis bio-oil. While the combustion of biomass can be carbon-neutral, the effects of biomass ash upon slagging during the iron-ore pelletizing process in a grate-kiln setup is unknown. In the present study, the effect of the interaction between the pellet dust and biomass-ash upon melt formation and the viscosity of the resulting melt, which can collectively affect melt-induced slagging, was theoretically assessed. The slagging potential of 15 different biomass fuels, suitable for the pelletizing process, was quantified and compared with one another and a reference high-rank coal using a thermodynamically derived slagging index. The replacement of coal with biomass in the pelletizing process is a cumbersome and challenging task which requires extensive and costly field measurements. Therefore, given the wide-ranging nature of the biomasses investigated in this study, a prescreening theoretical approach, such as the one employed in the present work, could narrow down the list, facilitate the choice of fuel/s, and help reduce the costs of the subsequent experimental investigations.

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Viscosity model for oxide melts relevant to fuel slags. Part 2: The system SiO 2 –Al 2 O 3 –CaO–MgO–Na 2 O–K 2 O

Cited by 34 publications

References 39 publications

Powder chemistry effects on the sintering of MgO‐doped specialty Al₂O₃

Powder chemistry effects on the sintering of MgO‐doped specialty Al₂O₃

Optimization of Slag Mobility of Biomass Fuels in a Pilot‐scale Entrained‐Flow Gasifier

The Feasibility of Replacing Coal with Biomass in Iron-Ore Pelletizing Plants with Respect to Melt-Induced Slagging

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Viscosity model for oxide melts relevant to fuel slags. Part 2: The system SiO 2 –Al 2 O 3 –CaO–MgO–Na 2 O–K 2 O

Cited by 34 publications

References 39 publications

Powder chemistry effects on the sintering of MgO‐doped specialty Al2O3

Powder chemistry effects on the sintering of MgO‐doped specialty Al2O3

Optimization of Slag Mobility of Biomass Fuels in a Pilot‐scale Entrained‐Flow Gasifier

The Feasibility of Replacing Coal with Biomass in Iron-Ore Pelletizing Plants with Respect to Melt-Induced Slagging

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Powder chemistry effects on the sintering of MgO‐doped specialty Al₂O₃

Powder chemistry effects on the sintering of MgO‐doped specialty Al₂O₃