Viscosity measurements and empirical predictions for some model gasifier slags

Hurst, H.J.; Novak, F.; Patterson, Joshua T.

doi:10.1016/s0016-2361(98)00162-8

Cited by 91 publications

(53 citation statements)

References 3 publications

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“…The published data of the liquidus [14] for slags in the anorthite field (dashed lines) in the "FeO"-CaO-Al 2 O 3 -SiO 2 slags are drawn to show the liquid/ anorthite phase boundary. Good agreement between the [14,15] calculated isoviscosity curves and the experimental data by Hurst et al [13,15] is apparent. At a given level of "FeO" of 10 wt pct and a given SiO 2 /Al 2 O 3 ratio, the viscosity decreases with increasing CaO content.…”

Section: B Coal-ash Slags For Gasifierssupporting

confidence: 61%

“…In some cases, fluxes, such as CaO and FeO x , are required to reduce the viscosity to below 25 Pa . s for smooth tapping in entrainedflow slagging gasifiers at operating temperatures of 1673 to 1773 K. [13] The model has been used to generate diagrams which demonstrated the viscosity variation with fluxing level. One example is shown in Figure 2.…”

Section: B Coal-ash Slags For Gasifiersmentioning

confidence: 99%

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From viscosity and surface tension to marangoni flow in melts

Sun

Zhang

Jahanshahi

2003

Metall Mater Trans B

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This article covers some of our recent work on slag viscosity, the surface tension of liquid Cu-O alloys, and the relative role of Marangoni and bulk flow on refractory wear in iron-silicate slags. A viscosity model developed for slags containing SiO 2 , Al 2 O 3 , Fe 2 O 3 , CaO, MgO, MnO, FeO, PbO, NiO, Cu 2 O, ZnO, CoO, and TiO 2 is capable of representing the effects of temperature, silica, and network-modifier cations within a wide range of temperatures and compositions. It forms a useful part of a computational package for multiphase-equilibrium (MPE) calculations and for predicting slag viscosities. The models are well applicable to a range of industrial slags (blast furnace, new iron making, base-metal and Platinum Group Metals (PGM) smelting, and coal-ash slags). The package has also some capability of predicting the viscosity of slags containing suspended solids. The surface tension of liquid copper-oxygen alloys has also been analyzed. The adsorption behavior of oxygen in liquid copper is well represented by the combined Langmuir-Gibbs isotherm. According to the rate data for silica-rod dissolution in liquid iron-silicate slags at 1573 K, the preferential attack at the slag line diminishes as the linear velocity of flow at the surface of the rotating silica rod reaches 9 to 16 cm/s. A tentative analysis gives the critical condition, that relates the critical Reynolds (Re) and Marangoni (Ma) number by the equation Re * 2 ϭ 0.13 Ma * . I. VISCOSITY OF SILICATE SLAGSACCURATE data for, and predictive methods to determine, the viscosity of silicate melts are always desirable to meet operational demands. During the past decade, a slag-viscosity model has been developed for calculation of the viscosity of slags containing the oxide components of SiO 2 , Al 2 O 3 , Fe 2 O 3 , CaO, MgO, MnO, FeO, PbO, NiO, Cu 2 O, ZnO, CoO, and TiO 2 at CSIRO Minerals and the former G.K. Williams Cooperative Research Centre for Extractive Metallurgy. [1][2][3][4] In the first step of modeling, the general behavior of viscosity in response to variations in the temperature and chemical composition of liquid slags was analyzed in detail based on a comprehensive collection of published viscosity data from binary to multicomponent silicate systems. It was revealed that, at a given temperature and when slags remain as homogeneous liquids, (1) SiO 2 has the strongest effect on viscosity, and viscosity increases with increasing SiO 2 content; (2) the effect of Al 2 O 3 depends on the presence of the charge compensators, such as alkali, alkali-earth, and other mono-or divalent oxides; (3) the addition of metal-oxide components, such as TiO 2 , Fe 2 O 3 , CaO, MgO, MnO, FeO, PbO, NiO, Cu 2 O, ZnO, and CoO, tends to reduce viscosity. The classification of oxide components as glass formers (SiO 2 ), modifiers (metal oxides), and amphoterics (Al 2 O 3 ), as proposed by Urbain et al., [5] can be adopted in distinguishing the structural roles of various oxides and treating their contributions to viscosity.During the second phase of the model ...

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Section: B Coal-ash Slags For Gasifierssupporting

confidence: 61%

Section: B Coal-ash Slags For Gasifiersmentioning

confidence: 99%

From viscosity and surface tension to marangoni flow in melts

Sun

Zhang

Jahanshahi

2003

Metall Mater Trans B

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“…On the other hand, the yielding condition of fused slag at 1 Pa•s is 1/15 less than or equal to the yielding condition of a coal gasifier furnace (8) . So, the slag-tapping hole of the coal ash fusing furnace for fiber manufacturing should be heated higher than the temperature of the gasifier furnace.…”

Section: Results Of Fused Slag Viscosity Measurementsmentioning

confidence: 86%

Yielding Conditions for Fiber Materials from Coal Ash Slag

Ishiga

Ishikawa

Orita

et al. 2011

JEE

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In this study, we focused on optimizing a part of the furnace and operating conditions of the fiber yielding system from fused coal ash to expand ash utilization for building materials; promotion of ash use is desirable because slag inhibits the elution of toxic heavy metals, such as Hg, Pb and As, to undetectable levels, making the fibers safe to use. In particular, the fiber materials from coal ash slag are expected to be used as thermal insulators and acoustic materials. We designed a coal ash fusing furnace which is suitable for the fiber manufacturing and recovery process. To manufacture fiber materials which are both safe and homogeneous, the slag viscosity had to be stabilized to approximately 1 Pa•s at the slag-tapping hole of the furnace. However, the slag temperature at 1 Pa•s was too high to measure. Thus, we estimated the slag temperature at 1 Pa•s using Riboud's and Urbain's expressions. To control the slag viscosity and temperature, CaCO 3 addition to coal ash was effective. When the basicity (CaO/SiO 2 (wt%/wt%)) of the coal ash sample was 0.98, the fused slag temperature at 1 Pa•s was estimated as 1563 ο C. Then, we verified that to yield 1 Pa•s fusing slag from 120 kg/h coal ash, the necessary fuel quantity of the coal ash fusing furnace was 40 kg/h coal and 4 m 3 N/h LPG.

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“…which is valid above the T cv , where  is the viscosity in poise, S is the silica ratio, and T is the temperature given in degrees K. Hurst et al [79] used a Haake high-temperature rotational viscometer with molybdenum and crucibles to measure viscosity of various slags. Similar to other researchers before them, they presented in contour plots the viscosity and the T cv of slags composed of 5% and 10% FeO.…”

Section: A Brief Review Of Various Viscosity Modelsmentioning

confidence: 99%

Slag Behavior in Gasifiers. Part II: Constitutive Modeling of Slag

Massoudi

Wang

2013

Energies

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Abstract:The viscosity of slag and the thermal conductivity of ash deposits are among two of the most important constitutive parameters that need to be studied. The accurate formulation or representations of the (transport) properties of coal present a special challenge of modeling efforts in computational fluid dynamics applications. Studies have indicated that slag viscosity must be within a certain range of temperatures for tapping and the membrane wall to be accessible, for example, between 1,300 °C and 1,500 °C, the viscosity is approximately 25 Pa·s. As the operating temperature decreases, the slag cools and solid crystals begin to form. Since slag behaves as a non-linear fluid, we discuss the constitutive modeling of slag and the important parameters that must be studied. We propose a new constitutive model, where the stress tensor not only has a yield stress part, but it also has a viscous part with a shear rate dependency of the viscosity, along with temperature and concentration dependency, while allowing for the possibility of the normal stress effects. In Part I, we reviewed, identify and discuss the key coal ash properties and the operating conditions impacting slag behavior.

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Viscosity measurements and empirical predictions for some model gasifier slags

Cited by 91 publications

References 3 publications

From viscosity and surface tension to marangoni flow in melts

From viscosity and surface tension to marangoni flow in melts

Yielding Conditions for Fiber Materials from Coal Ash Slag

Slag Behavior in Gasifiers. Part II: Constitutive Modeling of Slag

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