HLW Melter Control Strategy Without Visual Feedback VSL-12R2500-1 Rev 0

Integrated computational fluid dynamics (CFD) models are being developed to model the complex physics occurring within the high‐level waste melter for vitrification of legacy tank waste at the Hanford site. This study presents a validation of the integrated CFD model by using data from two experimental runs in a pilot‐scale melter. While the model uses several simplifying assumptions (such as constant heat sinks from a cooling jacket and inleakage of ambient air, steady state feed‐to‐batch conversion heat, and a cold cap model with a simplified shape), it closely predicts the molten glass (1150°C and 1175°C) and plenum temperatures (550°C) obtained from thermocouples during two pilot‐scale tests, with an average cold cap coverage of 80%. Additional simulations were performed to explore the sensitivity of the predicted plenum temperatures to variations in cold cap coverage (fraction of melt surface covered by the glass batch) and batch emissivity. The plenum temperature was found to be in the range of 606°C when cold cap coverage decreased from 95% to 70%. Cold cap emissivity had a smaller effect, increasing the plenum temperature by as much as 179°C when cold cap emissivity increased from 0.2 to 0.8. Maintaining a high cold cap coverage without overfeeding is important for a sustained melter operation with high glass throughput. This work provides a tool for achieving that goal in terms of correlating the plenum temperature with the cold cap coverage.

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

Effect of cold cap coverage and emissivity on the plenum temperature in a pilot‐scale waste vitrification melter

Abboud

Guillen

Pokorný

2020

Effect of water vapor and thermal history on nuclear waste feed conversion to glass

Marcial

Pokorný

Kloužek

et al. 2020

In commercial glass making, the presence of water vapor from oxyfuel combustion in the furnace atmosphere can cause excessive foaming and thus reduce the efficiency of heat transfer from the flames to the melt. 1-3 Löffler 4 compiled literature findings on the influence of water vapor on batch melting from the 1920s to the 1960s. He suggested that water can enter the glass melt from the glass batch provided that the batch absorbed water from the furnace atmosphere. Several papers studied melting behavior of glass batches under the effect of batch component moisture and chemically bonded water. Formation and dissolution of different phases during batch-to-glass conversion has also been examined. 4-8 Dubois and Conradt 9 found that water addition enhances silica particle dissolution in commercial flint and amber glass batches. Okamura and Uno 10 found that less time was required for complete conversion of batch to bubble-free melt when the water content of the melt was higher. However, Löffler 4 also points out that the amount of water that can enter the melt is limited. A substantial amount of work investigating the influence of water vapor on the melting and foaming behavior

Cold‐cap structure in a slurry‐fed electric melter

Ferkl,

Hrma,

Kloužek

et al. 2023

As glass batch is charged into an electric melter, a cold cap forms on the glass melt surface. Heat transfer to the cold cap from the molten glass below and the melter atmosphere above determines the melting rate. A mathematical model of the cold cap and the experimental kinetic data of the feed‐to‐glass conversion that were collected for several simulated low‐activity and high‐level waste melter feeds allowed us to develop relationships between the internal structure of the cold cap, its properties, its thickness, and the internal heat transfer. This contribution shows the distribution of major crystalline phases and the cumulative evolution of gases within the cold cap. It also examines the temperature, conversion degree, and heating rate the melter feed is experiencing during the passage through the cold cap and their effects on the cold‐cap bottom temperature and morphology, which are important for the computational fluid dynamics simulations of melters.This article is protected by copyright. All rights reserved