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Foaming during nuclear waste melter feeds conversion to glass: Application of evolved gas analysis
Author(s) -
Hujova Miroslava,
Pokorny Richard,
Klouzek Jaroslav,
Lee Seungmin,
Traverso Joseph J.,
Schweiger Michael J.,
Kruger Albert A.,
Hrma Pavel
Publication year - 2018
Publication title -
international journal of applied glass science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.383
H-Index - 34
eISSN - 2041-1294
pISSN - 2041-1286
DOI - 10.1111/ijag.12353
Subject(s) - materials science , porosity , decomposition , oxygen , glass transition , chemical engineering , composite material , chemistry , engineering , organic chemistry , polymer
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 H 2 O, CO 2 , NO, NO 2 , N 2 , and O 2 —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.