Thermal Flammable Gas Production from Bulk Vitrification Feed

Scheele, Randall D. ; McNamara, Bruce K. ; Bagaasen, Larry M.

Pacific Northwest National Laboratory (U.S.)

关键词: By-Products;    Testing;    Mixtures;    Nitrates;    Cellulose;   

DOI  :  10.2172/929207
RP-ID  :  PNNL-17491
RP-ID  :  AC05-76RL01830
RP-ID  :  929207

美国|英语

来源: UNT Digital Library

【 摘 要 】

The baseline bulk-vitrification (BV) process (also known as in-container vitrification ICV™) includes a mixer/dryer to convert liquid low-activity waste (LAW) into a dried, blended feed for vitrification. Feed preparation includes blending LAW with glass-forming minerals (GFMs) and cellulose and drying the mixture to a suitable dryness, consistency, and particle size for transport to the ICVTM container. The cellulose is to be added to the BV feed at a rate sufficient to destroy 75% of the nitrogen present as nitrate or nitrite. Concern exists that flammable gases may be produced during drying operations at levels that could pose a risk. The drying process is conducted under vacuum in the temperature range of 60 to 80°C. These flammable gases could be produced either through thermal decomposition of cellulose or waste organics or as a by-product of the reaction of cellulose and/or waste organics with nitrate or the postulated small amount of nitrite present in the waste. To help address the concern about flammable gas production during drying, the Pacific Northwest National Laboratory (PNNL) performed studies to identify the gases produced at dryer temperatures and at possible process upset conditions. Studies used a thermogravimetric analyzer (TGA) up to 525°C and isothermal testing up to 120°C to determine flammable gas production resulting from the cellulose and organic constituents in bulk vitrification feed. This report provides the results of those studies to determine the effects of cellulose and waste organics on flammable gas evolution