Cold-cap formation from a slurry feed during nuclear waste vitrification

Hujova, Miroslava; Kloužek, Jaroslav; Cutforth, Derek; Lee, Seungmin; Miller, M.; McCarthy, Benjamin P.; Hrma, Pavel R.; Kruger, Albert A.; Pokorný, Richard

doi:10.1016/j.ceramint.2018.12.127

Cited by 18 publications

(22 citation statements)

References 21 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…As a result, existing mathematical models of glass melting furnaces have paid little attention to the cold cap and its close proximity, where the heat transfer determines the rate of melting . Successful modeling would have to deal with the complexities associated with the transition zone between the cold cap and the melt, which contains dissolving solids, gas bubbles ascending from the melt, and is being stirred by horizontally moving large bubbles (cavities) from collapsing primary foam . Although a pioneering mathematical model of a cold cap has been carried out and a model of melt‐cold‐cap interaction is currently being developed, it may take some time for such efforts to reach a stage at which the main challenges are resolved.…”

Section: Introductionmentioning

confidence: 99%

Glass production rate in electric furnaces for radioactive waste vitrification

et al. 2019

Self Cite

View full text Add to dashboard Cite

Correlating the melting rates of feeds in electric melters with results of simple laboratory experiments can help evaluate melter feed additives and their effects on melting rate, and support the feed scheduling and plant operation. A recently proposed melting rate correlation (MRC) equation, relating the melting rate to melt viscosity, feed‐to‐glass conversion heat, and cold‐cap bottom temperature, was tested using data from experiments covering various feed compositions and melter operating parameters. The MRC equation is shown to reasonably represent the measured data and thus can be used to quantify how individual variables (melt viscosity, cold‐cap bottom temperature, conversion heat, melter operating temperature, and bubbling flux) affect the glass production rate.

show abstract

Section: Introductionmentioning

confidence: 99%

Glass production rate in electric furnaces for radioactive waste vitrification

et al. 2019

Self Cite

View full text Add to dashboard Cite

show abstract

“…Because primary foam is complex, inaccessible, and difficult to simulate in the laboratory, its rheology has not been fully investigated yet. Several attempts have been made to measure the viscosity of foaming melter feed at the stage where the glass‐forming melt has connected, but so far they only succeeded when the foam was collapsing …”

Section: Resultsmentioning

confidence: 99%

“…Several attempts have been made to measure the viscosity of foaming melter feed at the stage where the glass-forming melt has connected, but so far they only succeeded when the foam was collapsing. 10,11,53,56,57 Figure 5 shows our most recent viscosity results for two high-alumina melter feeds. The blue lines represent the viscosity of heat-treated melter feeds that are almost completely molten (though still containing small fractions of undissolved solids; see Table 2) and contain both primary and secondary bubbles (gases evolving from batch reactions and from redox reactions, respectively).…”

Section: Feed-to-glass Mass Ratio δH R (J G −1 )mentioning

confidence: 99%

“…Formation and spreading of the cold cap over the glass melt surface, and the resulting cold‐cap structure and thermomechanical properties, depend on the rheology of melter feed as it is converted to molten glass. The rheology of melter‐feed slurry and of the reaction layer have recently been investigated, thanks to a method that allowed simulating these early stages of conversion in the laboratory. However, simulating the foam layer and the TBL in the laboratory appears rather difficult and observing them directly in a melter operating in a steady state is virtually impossible.…”

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Viscosity of glass‐forming melt at the bottom of high‐level waste melter‐feed cold caps: Effects of temperature and incorporation of solid components

et al. 2019

Self Cite

View full text Add to dashboard Cite

During the final stages of conversion of melter feed (glass batch) to molten glass, the glass‐forming melt becomes a continuous liquid phase that encapsulates dissolving solid particles and gas bubbles that produce primary foam at the bottom of the cold cap (the reacting melter feed in an electric glass‐melting furnace). The glass‐forming melt viscosity plays a dominant role in primary foam formation, stability, and eventual collapse, thus affecting the rate of melting (the glass production rate per cold‐cap area). We have traced the glass‐forming melt viscosity during the final stages of feed‐to‐glass conversion as it changes in response to changing temperature and composition (resulting from dissolving solid particles). For this study, we used high‐level waste melter feeds—taking advantage of the large amount of data available to us—and a variety of experimental techniques (feed expansion test, evolved gas analysis, thermogravimetric analyzer‐differential scanning calorimetry, X‐ray diffraction, and viscometer). Starting with a relatively low value at the moment when the melt connects, melt viscosity reached maximum within the primary foam layer and then decreased to its final melter operating temperature value. At the cold‐cap bottom—the boundary between the primary foam layer and the thermal boundary layer—where physicochemical reactions of a melter feed influence the driving force of the heat transfer from the melt to the cold cap, the melt viscosity affects the rate of melting predominantly through its effect on the temperature at which primary foam is collapsing.

show abstract

“…Pellets of FDSS material were cut from the large 11.5 cm-diameter disk into cylinders ~13 mm in diameter and ~7 mm thick using a handheld rotary cutting tool. 51 FETs of direct slurry were performed by dispensing 0.9 g of slurry feed onto an alumina plate ("direct" slurry was not dried, powdered, or pelletized).…”

Section: Feed Expansion Testsmentioning

confidence: 99%

Effect of water vapor and thermal history on nuclear waste feed conversion to glass

Marcial

Pokorný

Kloužek

et al. 2020

Int J of Appl Glass Sci

Self Cite

View full text Add to dashboard Cite

In commercial glass making, the presence of water vapor from oxyfuel combustion in the furnace atmosphere can cause excessive foaming and thus reduce the efficiency of heat transfer from the flames to the melt. 1-3 Löffler 4 compiled literature findings on the influence of water vapor on batch melting from the 1920s to the 1960s. He suggested that water can enter the glass melt from the glass batch provided that the batch absorbed water from the furnace atmosphere. Several papers studied melting behavior of glass batches under the effect of batch component moisture and chemically bonded water. Formation and dissolution of different phases during batch-to-glass conversion has also been examined. 4-8 Dubois and Conradt 9 found that water addition enhances silica particle dissolution in commercial flint and amber glass batches. Okamura and Uno 10 found that less time was required for complete conversion of batch to bubble-free melt when the water content of the melt was higher. However, Löffler 4 also points out that the amount of water that can enter the melt is limited. A substantial amount of work investigating the influence of water vapor on the melting and foaming behavior

show abstract

Cold-cap formation from a slurry feed during nuclear waste vitrification

Cited by 18 publications

References 21 publications

Glass production rate in electric furnaces for radioactive waste vitrification

Glass production rate in electric furnaces for radioactive waste vitrification

Viscosity of glass‐forming melt at the bottom of high‐level waste melter‐feed cold caps: Effects of temperature and incorporation of solid components

Effect of water vapor and thermal history on nuclear waste feed conversion to glass

Contact Info

Product

Resources

About