Glass production rate in electric furnaces for radioactive waste vitrification

Lee, Seung Min; Hrma, Pavel R.; Pokorný, Richard; Kloužek, Jaroslav; Eaton, William; Kruger, Albert A.

doi:10.1111/jace.16463

Cited by 20 publications

(54 citation statements)

References 42 publications

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“…15 This can be attributed to the observation that it is not the foam volume, or the foam porosity, that controls the heat flow from the melt to the cold cap, but the temperature at which foam collapses. 4,14,27 Hence, reducing the extent of foaming without affecting the foam collapsing temperature would not noticeably affect the rate of melting.…”

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confidence: 99%

Effect of sucrose on foaming and melting behavior of a low‐activity waste melter feed

et al. 2019

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Reductants, such as sucrose (C12H22O11), are added to nuclear waste melter feeds containing high fractions of nitrates and nitrites to reduce excessive foaming during feed‐to‐glass conversion, decrease sulfate segregation, and increase technetium retention. The effect of sucrose on foaming and melting reactions during the conversion was examined using the feed volume expansion test, thermogravimetric analysis, evolved gas analysis, x‐ray diffraction, and scanning electron microscopy with energy dispersive x‐ray spectrometry. Different amounts of sucrose were added to vary the carbon to nitrogen (C/N) ratio in the melter feed. As the C/N ratio increased, the extent of foaming decreased, and the N2/NO ratio increased in the evolved gas. Significant foam suppression, rapid gas release at approximately 250°C, and reduction in transition metal oxides were observed at C/N > 1.1.

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Effect of sucrose on foaming and melting behavior of a low‐activity waste melter feed

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“…The heat flux is delivered from the melt below the batch (

Q_{B}

) and from the atmosphere above (

Q_{U}

), see Figure 1. As outlined and discussed by Lee et al, 48

Q_{B}

is linked to the temperature gradient in the melt at the interface with the batch

Q_{normalB} = ξ_{normalB} false(T_{MO} ‐ T_{B} false),

where

ξ_{B}

is the heat transfer coefficient,

T_{MO}

is the temperature of melt circulating under the batch (melter operating temperature), and

T_{B}

is the batch bottom temperature. Of the parameters necessary to solve Equations () and (),

Δ H

can be measured using DSC and

ξ_{B}

can be estimated from empirical data 48 or by mathematical modeling 49 .…”

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Conversion kinetics of container glass batch melting

et al. 2020

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Understanding the batch-to-glass conversion process is fundamental to optimizing the performance of glass-melting furnaces and ensuring that furnace modeling can correctly predict the observed outcome when batch materials or furnace conditions change. To investigate the kinetics of silica dissolution, gas evolution, and primary foam formation and collapse, we performed X-ray diffraction, thermal gravimetry, feed expansion tests, and evolved gas analysis of batch samples heated at several constant heating rates. We found that gas evolving reactions, foaming, and silica dissolution depend on the thermal history of the batch in a similar manner: the kinetic parameters of each process were linear functions of the square root of the heating rate. This kinetic similarity reflects the stronger-than-expected interdependence of these processes. On the basis of our results, we suggest that changes in furnace operating conditions, such as firing or boosting, influence the melting rate less than what one would expect without consideration of batch conversion kinetics.

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“…The legend shows melter operating temperature ( T MO ) values and indicates experimental data for which bubbling rate ( u B )> 5 m h ‐1 , RMSE is the root mean square error of the estimated melting rates, and R 2 and R 2 adj are the coefficient of determination and its adjusted value, respectively. Reprinted from Lee et al with permission from John Wiley and Sons…”

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Modeling batch melting: Roles of heat transfer and reaction kinetics

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Development of mathematical models of heat and mass transfer in glass‐melting furnaces began in the 1970s and progressed rapidly with advances in sophisticated experimental/numerical techniques and increasing computational power. Today, practically all newly built or rebuilt furnaces are optimized with these models to meet stringent quality requirements, reduce the unit costs of manufacturing, or control emissions. One remaining hurdle is to model the batch‐to‐glass conversion accurately enough to reliably assess the glass production rate. This article summarizes two key aspects of the batch‐conversion modeling—the heat transfer and the kinetics of conversion—and reviews the current state‐of‐the‐art approaches to simulating them. We critically examine the advantages of the commonly used heat transfer approach, but also explain that its predictive capabilities are significantly restricted by the dependence of batch thermal properties on the time‐temperature history. We argue that kinetic approaches to the batch‐conversion modeling would offer a significant improvement when coupled with the heat transfer approach. Finally, we summarize key areas requiring further research on the way toward a realistic model of the batch blanket.

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Glass production rate in electric furnaces for radioactive waste vitrification

Cited by 20 publications

References 42 publications

Effect of sucrose on foaming and melting behavior of a low‐activity waste melter feed

Effect of sucrose on foaming and melting behavior of a low‐activity waste melter feed

Conversion kinetics of container glass batch melting

Modeling batch melting: Roles of heat transfer and reaction kinetics

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