Heat transfer from glass melt to cold cap: Melting rate correlation equation

Journal Article · Mon Sep 24 04:00:00 EDT 2018 · International Journal of Applied Glass Science

DOI:https://doi.org/10.1111/ijag.12666· OSTI ID:1506686

Hrma, Pavel ^[1]; Pokorny, Richard ^[2]; Lee, SeungMin ^[1]; Kruger, Albert A. ^[3]

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1. Pacific Northwest National Laboratory, Richland, Washington
2. Laboratory of Inorganic Materials, Joint Workplace of the University of Chemistry and Technology Prague, and the Institute of Rock Structure and Mechanics of the ASCR, Prague Czechia
3. U.S. Department of Energy, Office of River Protection, Richland WA 99352.

Increasing the efficiency of all-electric melters is a hot topic not only in the waste glass melting industry, where the melting rate directly influences the life cycle of the cleanup process, but also in the commercial glass industry, where increasingly stringent environmental regulations and rapid development of renewable energy sources ask for transformation of traditional fossil fuel technology. Batch-to-glass conversion in an all-electric melter proceeds in the cold cap—a layer of reacting and melting material floating on molten glass. The heat transfer into the cold cap is controlled by convection and conduction in the thermal boundary layer on the melt side, and by the properties of the foam layer at the cold cap/melt boundary. An overview of factors affecting heat transfer is presented and assessed using data from laboratory and pilot-scale experiments. The heat flux can be improved by (i) decreasing glass melt viscosity, (ii) decreasing the temperature at which the foam starts to collapse at the cold cap bottom, and (iii) increasing melt convection by bubbling gas into the glass melt under the cold cap. Detailed understanding of the conversion process can guide the formulation of feeds that melt easily and quickly.

• Research Organization: Pacific Northwest National Laboratory (PNNL), Richland, WA (United States)
• Sponsoring Organization: USDOE
• DOE Contract Number: AC05-76RL01830
• OSTI ID: 1506686
• Report Number(s): PNNL-SA-130430
• Journal Information: International Journal of Applied Glass Science, Journal Name: International Journal of Applied Glass Science Journal Issue: 2 Vol. 10; ISSN 2041-1286
• Publisher: American Ceramic Society
• Country of Publication: United States
• Language: English