Alternate Reductant Cold Cap Evaluation Furnace Phase II Testing

Johnson, F. C.; Stone, Michael E.; Miller, Donald H.

doi:10.2172/1154718

Cited by 8 publications

(15 citation statements)

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“…The calcination time is the time required for the slurry feed to completely convert to oxides in the cold cap, during which it undergoes the dehydration, decomposition/calcination and fusion reactions. The basis for the assumed 2-hr calcination time is the data from a recent 1/12 th scale melter run, 9 which showed that the evolution of H 2 /CO (from the formate decomposition) stopped 10 minutes after the feeding stopped but NO/NO 2 continued to evolve even after 1 hour at more than 1/3 of the nominal rate during feeding. It was also observed during the LSFM 5 th Run that it took 2 to 3 hours to complete cold cap burn-off to a clear melt surface.…”

Section: Bases and Assumptionsmentioning

confidence: 99%

“…This scenario is likely if the electrodes are in or near the path of rising Ar bubbles, as demonstrated in a recent melter study using a coupon inserted into the melt pool directly in the path of Ar bubbles. 15 It will be interesting to see whether the entrainment rate of Ni still remains negative when the calculations are repeated in a future study using the data taken during non-bubbled operation.…”

Section: Elemental Entrainment Ratesmentioning

confidence: 99%

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Preliminary Analysis of Species Partitioning in the DWPF Melter

Choi

Kesterson

Johnson

et al. 2015

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The work described in this report is preliminary in nature since its goal was to demonstrate the feasibility of estimating the off-gas entrainment rates from the Defense Waste Processing Facility (DWPF) melter based on a simple mass balance using measured feed and glass pour stream compositions and timeaveraged melter operating data over the duration of one canister-filling cycle. The only case considered in this study involved the SB6 pour stream sample taken while Canister #3472 was being filled over a 20hour period on 12/20/2010, approximately three months after the bubblers were installed. The analytical results for that pour stream sample provided the necessary glass composition data for the mass balance calculations. To estimate the "matching" feed composition, which is not necessarily the same as that of the Melter Feed Tank (MFT) batch being fed at the time of pour stream sampling, a mixing model was developed involving three preceding MFT batches as well as the one being fed at that time based on the assumption of perfect mixing in the glass pool but with an induction period to account for the process delays involved in the calcination/fusion step in the cold cap and the melter turnover. Some of the key findings of this study include:  The proposed concept of estimating off-gas entrainment rates from measured feed and glass pour stream compositions appears feasible at least for the major species and thus additional case studies are warranted.  The overall entrainment rate from the bubbled DWPF melter was calculated to be 2.4% of the calcined solids fed, which is ~2X the design basis entrainment rate for the non-bubbled melter.  The average entrainment rate of the four major non-volatile sludge components, including Al, Fe, Mn and U, was calculated to be 2.7% fed, while that of the frit components, excluding Na, was 0.7%. It means that the entrainment rate of sludge is higher than that of frit by a ratio of 4:1, which is in qualitative agreement with the results of two off-gas deposit samples taken earlier.  Specifically, the calculated entrainment rates of Fe and Si were 0.6-0.7%, while those of Al, B, Mn, Th and U were higher, ranging from 1.9 to 5.6% with Mn at the highest.  The calculated entrainment rate of Na was 7.5%, of which a significant fraction could have been entrained via volatilization in the form of borates, sulfates, and halides.  The calculated entrainment rates of semi-volatile Cs and Cd ranged from 16 to 18%, while that of sulfur was estimated to be higher than 50%.  The calculated DWPF entrainment rates were in general higher than the DM1200 rates, which may be attributed in part to the formic acid used as the reductant for the DWPF feeds compared to sugar used for the DM1200 feeds, as demonstrated earlier in terms of increased pressure spikes with formic acid-based feeds. The much higher entrainment rates of Na and semi-volatiles in the DWPF melter could be reflective of actual operating conditions such as extended idling. The proposed concept will be tested further against ad...

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Section: Bases and Assumptionsmentioning

confidence: 99%

Section: Elemental Entrainment Ratesmentioning

confidence: 99%

Preliminary Analysis of Species Partitioning in the DWPF Melter

Choi

Kesterson

Johnson

et al. 2015

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“…A detailed description of the Phase 2 CEF test is given elsewhere along with the data collected. 3 The purpose of this study was to reconcile/analyze the data, develop a new off-gas surge basis, and develop a new DWPF melter off-gas flammability model for the NGA flowsheet. An earlier melter run performed in support of the down-select process showed that a significant fraction of the glycolate ion in the NGA flowsheet feed could remain as free acid and, upon entering the melter, volatilize and/or get entrained into the off-gas system.…”

Section: Introductionmentioning

confidence: 99%

“…4 Samples of the off-gas condensate and filtered solids were also analyzed, and the results on the extents of glycolate and particulate entrainments are presented in the Phase 2 Run report. 3 The CEF is a 1/11 th scale DWPF melter based on the effective melt surface area, excluding those areas occupied by various penetrations. 5 It was used in 2010 to study the impact of glass bubblers on melter off-gas surging, 6 and the frequency and intensity of the off-gas surges during bubbled and non-bubbled CEF operations were found to be prototypic of the DWPF melter pressure spike data collected during the 6 months before and 6 months after the bubblers went into operation.…”

Section: Introductionmentioning

confidence: 99%

“…In Stage 3, the CEF was run with the 100% acid stoichiometry feed containing 2X the normal level of antifoam under non-bubbled conditions, while maintaining the vapor space at 6 different temperatures (100%_NB_2X). A detailed description of the Phase 2 run is given elsewhere along with the full set of data on the CEF and off-gas system parameters, off-gas analysis and analytical results on the feed, glass, and condensate samples 3.…”

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confidence: 99%

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DWPF Melter Off-Gas Flammability Model for the Nitric-Glycolic Acid Flowsheet

Choi¹

2014

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Smith of Savannah River Remediation throughout the course of this study are greatly appreciated. The author also would like to recognize the immense contributions made by F. C. Johnson (Lead), and the rest of the CEF Team members to the successful planning and execution of the CEF Phase 2 Run. The author would like to particularly single out F. C. Johnson for her dedication and efforts to coordinate post-run analysis of a too-numerous-to-count number of samples and for keeping everything in order. The author also would like to point out that the dedication by J. R. Zamecnik in setting up the comprehensive off-gas sampling system and collecting and post-run processing of a very large amount of off-gas data was central to the successful completion of this study. A timely and thorough technical review of the calculations made in this study and the report content provided by F. G. Smith and W. E. Daniel are also appreciated. Finally, support, motivation and encouragement by management (Dave McGuire) were essential to helping the author stay focused and on track for the duration of this study.

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Cold‐cap structure in a slurry‐fed electric melter

Ferkl,

Hrma,

Kloužek

et al. 2023

Int J of Appl Glass Sci

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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

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Alternate Reductant Cold Cap Evaluation Furnace Phase II Testing

Cited by 8 publications

References 0 publications

Preliminary Analysis of Species Partitioning in the DWPF Melter

Preliminary Analysis of Species Partitioning in the DWPF Melter

DWPF Melter Off-Gas Flammability Model for the Nitric-Glycolic Acid Flowsheet

Cold‐cap structure in a slurry‐fed electric melter

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