Determination of heat conductivity of waste glass feed and its applicability for modeling the batch‐to‐glass conversion

Hujova, Miroslava; Pokorný, Richard; Kloužek, Jaroslav; Dixon, Derek R.; Cutforth, Derek; Lee, Seungmin; McCarthy, Benjamin P.; Schweiger, Michael J.; Kruger, Albert A.; Hrma, Pavel R.

doi:10.1111/jace.15052

Cited by 11 publications

(15 citation statements)

References 30 publications

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“…Hujova et al were able to calculate the heat conductivity of the batch and primary foam by applying literature models for multiphase heat transfer, including radiation, to x‐ray computed tomography (x‐ray CT) data of porosity and bubble size measured in situ, that is, as the temperature increased from room temperature up to the temperature of foam evolution and collapse; see Figure A. The results were in agreement with values determined by a heat penetration experiment (Figure B ). Although promising, the model depends heavily on batch and foam morphology data for a particular temperature history (or heating rate) that does not fully reproduce thermal conditions the batch undergoes in the glass‐melting furnace, where the heating rate experienced by batch particles varies over time.…”

Section: Future Needssupporting

confidence: 66%

“…The heat transfer models require a knowledge of material properties and conversion enthalpies. A number of studies on heat conductivity, density, heat capacity, or thermal diffusivity of various glass batches can be found in the literature . However, apart from being dependent on temperature, batch properties are functions of the temperature history of the batch during melting.…”

Section: Heat Transfer Modelingmentioning

confidence: 99%

“…For a nuclear waste batches, the foam porosity was reported to increase to above 80% at the heating rate 40 K/min (Figure B). Clearly, a change in porosity of the melting batch leads to a significant change in heat conductivity, both strongly affecting the solution of Equation ().…”

Section: Heat Transfer Modelingmentioning

confidence: 99%

“…(B) Comparison of theoretically predicted (dashed line) and measured (solid line) dependence of heat conductivity on temperature. Reprinted from Harris et al and Hujova et al with permission from John Wiley and Sons…”

Section: Future Needsmentioning

confidence: 99%

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Modeling batch melting: Roles of heat transfer and reaction kinetics

et al. 2019

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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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Section: Future Needssupporting

confidence: 66%

Section: Heat Transfer Modelingmentioning

confidence: 99%

Section: Heat Transfer Modelingmentioning

confidence: 99%

Section: Future Needsmentioning

confidence: 99%

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Modeling batch melting: Roles of heat transfer and reaction kinetics

et al. 2019

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“…This work presents one of the crucial steps towards a detailed foam layer model. The other important steps are investigating the morphology of the primary foam and developing a heat‐transfer model through the foam layer . Our ultimate goal is to combine all these parts to develop a representative model for the foam layer.…”

Section: Introductionmentioning

confidence: 99%

Foaming during nuclear waste melter feeds conversion to glass: Application of evolved gas analysis

Hujova

Pokorný

Kloužek

et al. 2018

Int J of Appl Glass Sci

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During the final stages of batch‐to‐glass conversion in a waste‐glass melter, gases evolving in the cold cap produce primary foam, the formation and collapse of which control the glass production rate via its effect on heat transfer to the reacting batch. We performed quantitative evolved gas analysis (EGA) for several HLW melter feeds with temperatures ranging from 100 to 1150°C, the whole temperature span in a cold cap. EGA results were supplemented with visual observation of batch‐to‐glass transition using the feed expansion tests. Upon heating, most of the gases—mainly H2O, CO2, NO, NO2, N2, and O2—evolve at temperatures below 700°C and escape directly to the atmosphere through open porosity. However, as open porosity closes when enough glass‐forming melt appears at ~720°C, the residual gas evolution leads to the formation of primary foam. We found that primary foaming is mostly caused by the decomposition of residual carbonates, though oxygen evolution from iron‐redox reaction can also play a role. We also show that the gas evolution shifts to a higher temperature when the heating rate increases. The implications for the mathematical modeling of foam layer in the cold cap are presented.

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