Controlling nitrogen oxides emissions (primarily NO and NO_2) is of great concern for many industries, including the ceramic. Over the past four years VSL researchers have examined several methods for limiting NO_x during the vitrification of nitrate and nitrite containing feeds. Tests were conducted on glass melters with nominal production rates ranging from 0.4 to 40 kg of glass per hour. The feed consisted of surrogate or actual nuclear and hazardous wastes, sometimes containing organic materials. Strategies, such as thermal inversion in the melter plenum, addition of urea to the feed and peroxide spraying into the exhaust gases, as well as various liquid scrubber arrangements were evaluated. The success of various technologies was measured with relation to chemical composition of the feed and the melter conditions, such as cold-cap formation, plenum temperature and glass pool bubbling rate. Acquired process material balance data suggests involvement of fairly complex mechanisms.
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