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Title: Experimental Investigation and Mathematical Modeling of Cold Cap Behavior in High-Level-Waste Glass Melter

The cold cap is a layer of reacting melter feed floating on the surface of molten glass in a glass-melting furnace. The cold cap consists of two distinct portions, of which the upper allows the reaction gases to escape through open pores, whereas the lower portion traps the gases within the continuous glass-forming melt, creating foam. The temperature span over the cold cap is ~1000 K. Data needed to simulate the cold cap mathematically include the kinetics of multiple reactions, reaction enthalpies, heat capacity, density, porosity, and heat conductivity as functions of both the temperature and the rate of heating. These data were produced via crucible experiments. The mathematical model has been completed. It relates the cold cap thickness, the rate of melting, the temperature field, and cold cap structure (foaming, dissolution of quartz particles, and formation and subsequent dissolution of crystalline phases, such as spinel) to the cold cap bottom temperature, the fraction of heat flow to the upper cold cap surface, the melt foaminess, and the chemical and physical nature of melter feed materials. To verify the model, cold caps were produced in a laboratory-scale melter and their structure is currently investigated.
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Conference: Advances in Materials Science for Environmental and Energy Technologies III. Ceramic Transactions, 250:137-145
T Ohji, et al; John Wiley & Sons, Inc., Hoboken, NJ, United States(US).
Research Org:
Pacific Northwest National Lab. (PNNL), Richland, WA (United States)
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United States