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To understand the wood-fuel contamination problems faced by the ancient glass industry, some Roman glass fragments and beads were analysed for carbon by the elegant, non-destructive deuteron activation technique based on C-12(d,n)N-13 nuclear reaction. Carbon was found in all analysed glasses, covering a mass concentration range from 160 ppm to 2.2%, indicating that some fuel contamination was present in all samples. The higher concentration of 0.94 to 2.2% observed in some beads indicates that carbon was added intentionally as a "component" to the glass melt to obtain an amber colour. [ABSTRACT FROM AUTHOR]

Fused cast Al2O3-ZrO2-SiO2 (AZS) refractory is the key building material of glass furnace. Calcined aluminum oxide powder and ordinary industrial aluminum oxide powder were used as raw materials to prepare fused cast AZS refractories, respectively. The structure and properties of the two fused cast AZS refractories were compared and analyzed by lithofacies analysis, X-ray diffraction analysis, and energy dispersive spectroscopy analysis, etc. The results indicate that fused cast AZS refractory material prepared by ordinary industrial aluminum oxide powder has the incomplete conversion γ-Al2O3, which leads to uneven distribution of Al2 O3-ZrO2 eutectic. The alumina phase in the fused cast AZS refractory prepared by calcined alumina oxide powder is α-Al2O3. The fused cast AZS refractory prepared by calcined aluminum oxide has less baddeleyite, more Al2O3-ZrO2 eutectic and more uniform distribution of glass phase. The distribution of crystal structure affects amount of glass phase exudation and corrosion resistance to molten glass. The glass phase exudation of the fused cast AZS refractory prepared by calcined aluminum oxide powder is 0. 57 percentage points lower than that of fused cast AZS refractory prepared by ordinary industrial aluminum oxide powder. The corrosion resistance to molten glass of fused cast AZS refractory prepared by calcined aluminum oxide power is 0. 15 mm/24 h higher than that of fused cast AZS refractory prepared by ordinary industrial aluminum oxide power. [ABSTRACT FROM AUTHOR]

A glass production furnace requires a considerable amount of energy to allow the correct glass melting process. In this work, a CFD model has been developed in order to simulate the convective flow movements within the molten glass bath of the glass furnace. A heat flux profile has been assigned to the glass free surface to model the combustion process, and the glass has been modelled with thermophysical properties variable with temperature based on its chemical composition. The model has been validated by comparing the flow structure and temperature with a reference work. Subsequently, a flow analysis has been carried out by using different shapes for the heat flux profile and by varying its main parameters. The above heat release profiles are representative of different settings of the combustion operating points and can be useful to understand the effects of different flames (i.e., from different fuels also) on the glass flow structure. It has been demonstrated that only the thermal distribution with a maximum generates two convective macro-cells: the first is necessary for the glass melting, the second for its homogenization. It has also been observed that the length of these vortices is related to the flame length. However, a portion of the flow exits directly from the throat (furnace exit port) without entering into the second cell; a low-quality product will be generated in this case. [ABSTRACT FROM AUTHOR]

In the glass manufacturing industry, electric melting would greatly improve the energy efficiency and reduce the pollution emission, which agrees with the target of peak carbon and carbon neutrality. In this work, electric boosting system is introduced into float glass furnace, and the influence of varied electrodes positions on glass melting process is investigated. The glass temperature and velocity fields of glass melting tank are obtained using numerical modeling. According to the temperature and velocity fields, the glass trajectories at glass melting tank are tracked, and the residence time distribution and quality indexes of glass melt are statistic as well. Ultimately, the evaluation method is proposed to predict the glass quality and melting efficiency of glass furnace, which is based on the quality indexes of critical particles and longest residence time of glass melt. The accelerated batch melting process and stable convection flow are obtained as the electrodes are installed under batch blanket. Furthermore, the improved glass quality and melting efficiency of glass furnace is obtained. The study is expected to promote the application and optimization of electric boosting system in large‐scale float furnace, which would accelerate the use of clean energy in glass manufacturing industry. [ABSTRACT FROM AUTHOR]

In the present paper, a novel method for numerically calculating the process of forced bubbling in an industrial-scale glass furnace was developed. The bubble chain in the glass tank was substituted with a locally acting buoyancy source. Unlike the few previously presented models, the following improvements were included: 1) Bubble characteristics were determined by running separate Eulerian multiphase simulations. Specific coupling to the actual tank model was integrated so that the induced buoyancy was calculated directly on the basis of the practical application. 2) Changes of the bubble properties and the induced buoyancy in vertical direction were analyzed. 3) The practical gas input per bubbler nozzle was used as the single input parameter. All essential model quantities could thus be expressed as direct functions of this variable. A detailed investigation of the induced buoyancy force revealed its linear dependency on the gas flow rate. A high degree of convective mixing as well as a local reduction of surface temperatures of up to 200 K could be demonstrated with the glass tank simulation results. In total, the presented models can be effectively applied in practical furnace dimensioning processes to determine both the ideal bubbler placement and the optimal mode of operation. • Efficient single-phase approach for the bubble chain in the glass melt. • Separate Eulerian multiphase simulation for obtaining bubble properties. • Model coupling in terms of the bubble chain force respectively temperature data. • Observation of a linear dependency between the induced buoyancy and the gas input. • Demonstration of convective mixing and local temperature reduction in the glass tank. [ABSTRACT FROM AUTHOR]

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Copyright of Bulletin of the Chinese Ceramic Society is the property of Bulletin of the Chinese Ceramic Society Editorial Office and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

The activation energy of glass melt viscosity, η, is nearly constant at temperatures at which η < 100 Pa s. Provided that the preexponential factor is a composition-independent constant, only the activation energy is a function of composition, and viscosity–composition relationships of utmost simplicity can be formulated to provide a welcome advantage in computational fluid dynamics modeling of glass melting furnaces processing multicomponent glasses. Using a dataset with over 3000 viscosity values acquired experimentally for a temperature and composition region of low-activity nuclear waste glasses, we have generated three linear models for viscosity as a function of temperature and composition. Model A quantifies the effects of 20 viscosity-influencing components. Model B achieves a similar prediction accuracy after setting aside volatile components, whose concentrations may vary during glass processing. A parsimonious Model C reduces the number of viscosity-influencing components to a mere seven: Al2O3, B2O3, CaO, Li2O, Na2O, SiO2, and Others. In each model, the "Others" component summarizes the fractions of the remaining components. For all three models, the component coefficients are determined with a high confidence (low standard error) and a high coefficient of determination: 0.972 for Model A, 0.970 for Model B, and 0.949 for Model C. [ABSTRACT FROM AUTHOR]

Aluminum-containing raw materials for the synthesis of aluminum-borosilicate glasses for E-glass fiber should be rationally chosen to comprehensively assess their effect on the glass melting processes. The characteristic properties of the chemical, phase, and granulometric composition of the raw materials such as metallurgical alumina, non-metallurgical alumina, disthene, and kaolin were under study. It was revealed that the type of aluminum-containing raw materials significantly influenced the rate of glass formation processes and heat consumption required for these processes. The efficiency of aluminum-containing raw materials is influenced by the following factors: the phase composition, which determines the sequence and rate of phase transformations, as well as the heat-absorbing ability of the furnace batch and glass melt. The most energy-efficient material is non-metallurgical alumina of the White Alumina brand. Using it facilitates saving energy resources for glass formation processes from 2.64% to 16.30% as compared with other types of aluminum-containing raw materials. The use of kaolin proves to be the least efficient due to the additional energy consumption for the process of destruction of the crystal structure of kaolinite, the reduced thermal conductivity of the batch, and the thermal transparency of the borosilicate glass melt. [ABSTRACT FROM AUTHOR]

A method for modeling the electric glass melting process, which allows obtaining information about the commonality of electric and thermal processes occurring in the glass mass inside an electric glass-melting furnace, has been developed. The melting tank of the furnace is made of electrically conductive chromium oxide. The study was performed by way of modeling using an EHDA integrator, which resulted in the construction of two versions of pilot electric furnaces with different orientation of the electric field lines and a pilot-commercial furnace capable of melting 7 t/day of E-glass, widely used in the fiberglass manufacturing. [ABSTRACT FROM AUTHOR]

Bubbling has been a constant feature in the float glass furnace since the inception of this melting technology. Although bubbling can enhance glass quality, economize energy consumption, and stabilise the production process, the quality of products from some float glass production lines after using bubbling are worse than when they are not used. The main reason is that bubbling affects the flow of the molten glass in a furnace, and the effects may be beneficial or harmful to the quality of the final glass product. In this paper, molten glass in a China typical float glass furnace is taken as the research object, and the mechanism of action of bubbling on the glass flow in the furnace was studied in detail through simulation. The beneficial and harmful factors of bubbling to the glass will be analysed and discussed, and scientific and reasonable explanations and optimisation suggestions will be given. This work is the first part of this study. The conditions with and without bubbling were compared by the VOF model, and the influence of bubbling on the temperature field, velocity field, and overall liquid circulation of molten glass were explored. Specially, on the basis of study, this paper proposes the principle of the rational distribution of the glass fluid flow under the bubbling conditions. This work can advance understanding of the effect of bubbling on the fluxing, homogenisation and regularity of molten glass, as well as on the flow regularity of the glass liquid flow, and provide the theoretical basis and preconditions for the optimisation of the proposed bubbling related parameters. [ABSTRACT FROM AUTHOR]

The dynamics of soda‐lime‐silica glass grain melting is investigated experimentally using a nonintrusive technique. A cylindrical alumina crucible is filled with glass cullet and placed into a furnace illuminated by an X‐ray source. This glass granular bed is gradually heated up to 1100°C, leading to its melting and the generation of a size‐distributed population of bubbles rising in the molten glass. An image processing algorithm of X‐ray images of the cullet bed during melting allows the characterization of bubbles size distribution in the crucible as well as their velocity. The introduction of tin dioxide μ‐particles in the glass matrix before melting enhances the texture of the images and makes possible the determination of the bubble‐induced molten glass velocity field by an optical flow technique. The bubble size distribution can be fitted by a log‐normal law, suggesting that it is closely related to the initial size distribution in the cullet bed. The liquid motion induced by the bubbles in Stokes' regime is strongly affected by the flow confinement and the determination of bubble rising velocity along its trajectory unveils the existence of local tiny temperature fluctuations in the crucible. Overall, the measuring techniques developed in this work seem to be very promising for the improvement of models and optimization of industrial glass furnaces. [ABSTRACT FROM AUTHOR]

Copyright of Journal of Machine Construction & Maintenance is the property of Institute for Sustainable Technologies - National Research Institute and its content may not be copied or emailed to multiple sites or posted to a listserv without the copyright holder's express written permission. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)

Possible regimes of gas efflux into a layer of molten glass through a horizontal tuyere as well as the structure of the blowing zone formed in the process are investigated using a physical model of a glass furnace with a bubbling layer. The initial data required for uniqueness are obtained in a mathematical model of mixing of molten glass in a tank furnace. [ABSTRACT FROM AUTHOR]

Ascientifically substantiated applied method of performing engineering calculations of the thermal resistance of the wall layer has been developed. This procedure makes it possible to take account of additional factors-temperature of the melt and composition of the molten glass in the melting tank - and make more accurate predictions of the temperature in corrosion-active zones of the refractory barriers of glassmaking furnaces. [ABSTRACT FROM AUTHOR]

The quality of a glass melting process is determined by the melting in performance, the sand grain dissolution and the removal of gas bubbles by fining. For good quality it is essential that each trajectory/path starting from batch charging to the throat or waist of the tank shows complete melting and fining. Each part of the glass melt should be exposed to temperatures such that fining can occur. The fining onset temperature and melting performance for an industrial glass tank depends on the batch composition, sand grain size, type and amount of fining agent, furnace atmosphere and the redox number of the batch. Laboratory experiments are carried out to determine the most important parameters for industrial batches. The results of these laboratory experiments are used as input to the CFD (Computational Fluid Dynamics) model GTM X, which then provides the temperature and flow fields in the industrial melting tank, along with the calculation of the individual glass melt trajectories. This combination of experiments and CFD simulation proves to be a very powerful tool for determining the fining and melting performance of industrial furnaces. Special attention will be paid to the location of the fining zone, with respect to the convection flows in the melt. [ABSTRACT FROM AUTHOR]

Erosion of the refractory lining in molten glas s furnaces is a major problem for the glass manufacturing industry. When erosion on the walls is not detected early enough, it may lead to a molten glass leak through the refractory lining and may result in the suspension of production for several weeks. In som e cases, a catastrophic a ccident may also result. The glass penetration typically starts small within the insulation layer and takes anywhere from a few weeks to several months to penetrate through the in sulation layer and result in major catastrophic furnace leak. Therefore, detecting an early s tage glass penetration within the insulation layer and identifying weak refractory linings will result in safer and longer furnace operation through preventive and proactive maintenance. To address this m ajor industry need, we are developing a non-destructive sensor technology for tomographic imaging of insulation and refractory lining. This sensor will identify early stage glass penetration into insulation and identify weak refractory spots for preventive and proactive maintenance. We have already devel oped a sensor that m easures the residual AZS thickness on operational glass furnaces. We have also shown the f easibility of mapping interior walls of insulation layers for glass penetration in an operational furnace. Lastly, the same sensor technology is capable of detecting voids and defects in cold refractories. In this paper, we will discuss the underl ying fundamentals behind the proposed sensor technology, the m easurement results pertainin g to feasibility and in-situ tes ts on operational furnaces, and the path forward to an integrated sensor system for smart (self-sensing) furnaces. [ABSTRACT FROM AUTHOR]

This paper presents the failure analysis of alumina–zirconia–silica (AZS) refractory bricks located in the glass level in the tank of a furnace for melting glass, since is the region where there is greater wear respect to the base. The wear of the refractory was evaluated after 4 years of campaigning, under thermal and mechanical loading during the glass manufacture. The analysis by scanning electron microscopy shows high porosity and the presence of alkalis is also detected from the glass composition, being the phase alumina–zirconia–silica (AZS),the one that shows better resistance to erosion wear by displacement of the molten glass. The analysis yielded the following mechanisms of chemical wear, removal of the vitreous phase toward the surface of the sample due to the increase in temperature of the furnace, and therefore attack by vapors through the porosity caused by the exudation of the vitreous phase, as well as deterioration of the microstructure of the refractory due to the formation of cracks. Because it is considered as the main problem in these types of furnaces, the erosion wear is related to the flows of convection currents within the tank, this occurs at the level of the glass, as it is at this point, where it has concentration of thermal and mechanical loads due to movement of the molten glass. [ABSTRACT FROM AUTHOR]

The results of mathematical modeling of the thermal operation of a 280 tons/day glassmaking furnace with a horseshoe flame are presented. It is shown that specific extraction of molten glass 2.5 tons/(m∙day) and specific heat flow 4563.8 kJ/kg with gas heating of the furnace can be attained without additional electric heating of the melting tank. [ABSTRACT FROM AUTHOR]

The process of making float-glass in large-tonnage glassmaking furnaces is analyzed. The optimal values of the rate and duration of melting and cooling of the molten glass are determined. It is shown that the melting time of the glass is 48 - 72 h and depends on the content of the cullet in the batch. The glass melt remains chemically and structurally uniform with cooling rates 10 - 12 K/h and cooling times 20 - 24 h, which yields glass of optimal quality. [ABSTRACT FROM AUTHOR]

The physical-chemical interactions at contact of molten glass with refractories in a glassmaking furnace, mostly electricity melted baddeleyite - corundum (bacor), are examined. Three basic interactions are discussed: surface phenomena, chemical interactions, and transport phenomena. [ABSTRACT FROM AUTHOR]

This article describes the parameters for the efficient operation of modern glass-founding furnaces designed to produce commercial glass. It also describes the structure of the heat-insulating and refractory materials used to line such furnaces. Requirements are formulated for the quality of electrofused alumina-zirconia-silica (AZS) refractories used in high capacity glass-founding furnaces. An efficient scheme is proposed for using AZS refractories to line the hot zone of a glass-founding furnace with a capacity of 280 tons/day. [ABSTRACT FROM AUTHOR]

Glass manufacturing is an energy-intensive process in which oxy-fuel combustion can offer advantages over the traditional air-blown approach. Examples include the reduction of NOx and particulate emissions, improved furnace operations and enhanced heat transfer. This paper presents a one-dimensional mathematical model solving mass, momentum and energy balances for a planar oxygen transport membrane module. The main modelling parameters describing the surface oxygen kinetics and the microstructure morphology of the support are calibrated on experimental data obtained for a 30 μm thick dense La0.6Sr0.4Co0.2Fe0.8O3-δ (LSCF) membrane layer, supported on a 0.7 mm porous LSCF structure. The model is then used to design and evaluate the performance of an oxygen transport membrane module integrated in a glass melting furnace. Three different oxy-fuel glass furnaces based on oxygen transport membrane and vacuum swing adsorption systems are compared to a reference air-blown unit. The analysis shows that the most efficient membrane-based oxyfuel furnace cuts the energy demand by ~22% as compared to the benchmark air-blown case. A preliminary economic assessment shows that membranes can reduce the overall glass production costs compared to oxyfuel plants based on vacuum swing adsorption technology. [ABSTRACT FROM AUTHOR]