Modeling Melt Rate for DWPF: A Preliminary Assessment

Choi, An-Seop; Peeler, David K.; Edwards, T. Bradley

doi:10.1002/9781118407950.ch18

Cited by 2 publications

(5 citation statements)

References 5 publications

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“…Table 3 shows that the total modifier field strength of the SMEM-2 glass was the highest, but its estimated melting rate in Table 2 was 13% higher than that of SMEM-4. 13,25 Thus, formate has less adverse impact on melting rate than nitrate, which decomposes over a much wider temperature range extending above~900°C. But at the same time, high aluminum also appears to help melting of the cold cap by making the resulting melt more viscous and thus sluggish in closing the channels through which gases evolving at later stages of melting can escape.…”

Section: Factors Affecting Melting Ratementioning

confidence: 99%

“…Specifically, the formate decomposes early in the melting process releasing two-thirds of its calcine gases by~450°C. 13,25 Thus, formate has less adverse impact on melting rate than nitrate, which decomposes over a much wider temperature range extending above~900°C. 25,26 This explains why SMEM-2 exhibited the largest bed expansion (because it contained the highest concentration of nitrate).…”

Section: Factors Affecting Melting Ratementioning

confidence: 99%

“…Melting rate data with a higher degree of quantitative resolution and less subjectivity than the visual method can provide are needed to support ongoing frit optimization efforts to maximize the DWPF glass production rate. 13 An alternate method of assessing relative melting rates has recently been developed at SRNL employing X-ray computed tomography (CT). 14 This method involves X-ray scanning of heat-treated samples, performing CT on the X-ray images to build 3D volumetric data, and adaptive segmentation analysis of the 3D data to quantify distinct regions within the sample matrix based on material density and morphology.…”

Section: Introductionmentioning

confidence: 99%

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Investigation of high‐level waste glass melting using X‐ray computed tomography

Choi

Miller

Immel

et al. 2016

Int J of Appl Glass Sci

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A method has been developed to quantitatively assess the melting behavior of simulated nuclear waste glasses in a 5‐cm‐diameter stainless steel beaker heated from the bottom. The method applies X‐ray scanning and computed tomography to build three‐dimensional volumetric data of a heat‐treated sample and performs an adaptive segmentation analysis of the volumetric data to identify morphologically distinct regions in the sample matrix and quantify the amount of material in each region based on computed tomography density. The method was applied to two different series of simulated high‐level waste glass melter feeds, and the results showed that it provides detailed images of samples at various stages of melting, including distribution of gas bubbles of varying sizes within the sample matrix, as well as a quantitative measure of how fast various waste/frit feeds melted relative to each other. The results show that the melting rate is influenced by the rate of calcine gas evolution, melt viscosity, and the presence of modifier ions in the feed.

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Section: Factors Affecting Melting Ratementioning

confidence: 99%

Section: Factors Affecting Melting Ratementioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Investigation of high‐level waste glass melting using X‐ray computed tomography

Choi

Miller

Immel

et al. 2016

Int J of Appl Glass Sci

View full text Add to dashboard Cite

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“…Since a detailed description of the cold cap and MOG dynamics models along with the validation results is given elsewhere, [6][7][8] only some of the key features of each model are highlighted next.…”

Section: Existing Modelsmentioning

confidence: 99%

“…The gas and solids products are allowed to reach equilibrium in each stage, before the former is passed on to the next stage up, while the latter is passed on to the next stage down, thereby maintaining countercurrent gas-solids flows between stages. 6 The temperature of each stage is set progressively higher from 700°C at the top (Stage 1) to the final melt temperature of 1150°C at the bottom (Stage 4). The temperature of Stage 1 was set based on the finding that the calculated molar ratio of CO to CO 2 in the calcine gas at 700 o C closely matched measured data.…”

Section: Cold Cap Modelmentioning

confidence: 99%

Melter Off-Gas Flammability Assessment for DWPF Alternate Reductant Flowsheet Options

Choi¹

2011

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EXECUTIVE SUMMARYGlycolic acid and sugar are being considered as potential candidates to substitute for much of the formic acid currently being added to the DWPF melter feed as a reductant. A series of small-scale melter tests were conducted at the Vitreous State Laboratory (VSL) in January 2011 to collect necessary data for the scoping assessment of the impact of these alternate reductants on the melter off-gas flammability. The resulting data were analyzed in this work with the aid of modeling and re-baselined to reflect the DWPF melter operating conditions. Based on the results of these steady state analyses presented in this report, the following conclusions can be drawn:1. The baseline formic acid flowsheet feed has ~3X higher melter off-gas flammability potential than either the glycolic acid or sugar-based flowsheet feed at measured vapor space temperatures ≤ 500 o C.2. The melter off-gas flammability potentials of the glycolic and sugar-based flowsheet feeds are similar at measured vapor space temperatures ≤ 500 o C.3. The 3X difference in melter off-gas flammability potential between the baseline and either alternate reductant feeds is expected to decrease significantly at typical vapor space operating temperatures  500 o C for both bubbled and non-bubbled operations due to increased kinetics of H 2 and CO oxidation.4. Bubbling increases the melter off-gas flammability potential likely due to increased feed rate at a relatively constant air purge rate.5. It appears that over 50% of the glycolate detected by IC in the glycolic flowsheet feed remained un-dissociated and exited the melter as such, thus having no significant impact on either the glass redox or melter off-gas flammability potential. The condensed glycolic acid will then have to be neutralized and recycled back to the Tank Farms.

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Modeling Melt Rate for DWPF: A Preliminary Assessment

Cited by 2 publications

References 5 publications

Investigation of high‐level waste glass melting using X‐ray computed tomography

Investigation of high‐level waste glass melting using X‐ray computed tomography

Melter Off-Gas Flammability Assessment for DWPF Alternate Reductant Flowsheet Options

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