Melting rate correlation with batch properties and melter operating conditions during conversion of nuclear waste melter feeds to glasses

Abstract

Mathematical models of glass melting furnaces are incomplete in the sense that they do not estimate the rate of glass production (the rate of melting). Instead, they attempt to optimize melter efficiency and product quality for a specified production rate with other experimentally measured data. [1][2][3][4][5][6][7][8][9][10][11][12][13][14] The melting rate correlation (MRC) attempts to bypass this

Conversion degree and heat transfer in the cold cap and their effect on glass production rate in an electric melter

“…35 As the top surface is mostly covered by boiling slurry, the top temperature 𝑇 𝑈 = 100 • C. The conversion kinetics within the cold cap depends on the heating rate within the cold cap and, thus, on the heat fluxes from above 𝑄 𝑈 and below 𝑄 𝐵 to the cold cap. This interdependence between 𝑇 𝐵 , 𝑄 𝑈 , and 𝑄 𝐵 links feed composition and melter operating conditions with the rate of melting, [36][37][38] affecting the driving force for heat transfer from the melt into the cold cap. 37,38 Directly implementing the full mathematical model of the cold cap into the CFD melter model would be computationally prohibitive because it would entail solving coupled differential equations at each cold cap boundary cell face at each time step.…”

“…19 Table 1 lists the adjustable parameters of the kinetic model and the associated fraction of dissolved silica at the cold cap bottom, 𝑓 𝐵 . 19 Table 1 also lists the total conversion enthalpy, which is a sum of the water evaporation heat, the feed reaction TA B L E 1 Fitted parameters of Equations ( 4)-( 6) 19 and other material properties 19,36,38,[42][43][44][45] heat, and the sensible heat. The water evaporation heat was calculated from the water content and specific heat of water vaporization.…”

Visual Observation of Foaming at the Batch-Melt Interface During Melting of Soda-Lime-Silica Glass

“…In our recent studies [28][29][30], we suggest that the dominant factor for the heat transfer into the batch is the so called batch bottom temperature, T B , because for most feeds that do not foam excessively, the main resistance to the heat transfer is on the melt side; the foam thickness, d F , is a variable that "adjusts" itself to accommodate the heat incoming from the melt. However, we argued that the T B estimated using common laboratory techniques, such as FET, is far from precise, especially because of the differences between in the foam behavior in a heated laboratory sample and at the bottom of the batch in a large glass-melting furnace [12].…”

Incorporation limit of MoO3 in sodium borosilicate glasses

“…To our best knowledge, the incorporation limit and local structure of molybdenum cations have not been clearly correlated with the amount of available charge compensator cations, which varies as a function of the ratio of molar content of B 2 O 3 to the total molar content of SiO 2 and B 2 O 3 in the sodium borosilicate system. This study investigates the change in the mechanism of the local structure near molybdenum cations upon changing the ratio of B 2 O 3 to SiO 2 in the sodium borosilicate system, a fundamental solvent for HLW 23–25 . Furthermore, the relationship between the incorporation limit of MoO 3 and the local structure of molybdenum cations was elucidated.…”

“…This study investigates the change in the mechanism of the local structure near molybdenum cations upon changing the ratio of B 2 O 3 to SiO 2 in the sodium borosilicate system, a fundamental solvent for HLW. [23][24][25] Furthermore, the relationship between the incorporation limit of MoO 3 and the local structure of molybdenum cations was elucidated.…”