Browsing by Author "Faber, Anne J."
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- ItemApplication of ultrasonic measuring techniques in industrial glass melting(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1991) Faber, Anne J.; Simonis, Frank; Breeuwer, René; Waal, Henk deThe potential applications of ultrasonic measurements in glass melts have been studied, using a measuring system comprising ultrasonic waveguides of polycrystalline translucent Al2O3. These high-temperature buffer rods serve to transport ultrasonic signals into the glass melt and to receive acoustic echoes generated in the melt, respectively. The fundamental acoustic properties of a soda-lime-silica glass composition as a function of temperature have been obtained experimentally: The observed sound velocity varies from 2.86 km/s at 1150 °C to 2.70 km/s at 1300 °C. The observed attenuation of 1 MHz waves has a minimum at 1300 °C of 840 dB/m. For 100 kHz waves the attenuation is a factor 100 lower. It is concluded that 100 kHz ultrasonic signals can be utilized for detection of bubbles with critical radii (≥ 0.2 mm) in a feeder, for measurement of glass flow velocities and for measurements of glass temperature. For measurement of the residual thickness of refractory bricks of a glass tank, application of echo acoustic sensors an the outer surface of the wall probably is more practical.
- ItemDevelopment of an ultrasonic method to determine the residual thickness of refractory blocks(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1993) Fleischmann, Bernhard; Faber, Anne J.; Breeuwer, RenéAn ultrasonic method was developed to measure the residual thickness of refractory blocks at an operating glass melting furnace. This ultrasonic measuring method was used to determine the thickness of zirconia-based refractories on a small laboratory glass melting furnace. Two ultrasonic transducers with a silica delay and a coupling media were used to measure the transition time, that the ultrasonic signal needs with the applied echo method. The results of the thickness measurements at cold and hot refractory blocks were compared. The investigations prove the possibility to employ the ultrasonic device for determining the residual thickness of refractory blocks.
- ItemInfluence of water dissolved in the structure of soda-lime-silica glass on melting, forming and properties: state-of-the-art and controversial issues Report of the International Commission on Glass (ICG) Technical Committee 14 "Gases in Glass"(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1999) Geotti-Bianchini, Franco; Brown, John T.; Faber, Anne J.; Hessenkemper, Heiko; Kobayashi, Sho; Smith, Ian H.The paper summarizes the information available about the water content of soda-lime-silica glass, the factors that influence it and the influence exerted by water in glass on redox and sulphur retention, on fming, on the melting and forming behaviour, workability and the physical and chemical properties of the melt. Such issues were discussed by the authors in their presentations at the first Forum on Water in Glass, organized in 1997 by Technical Committee 14 (TC 14 "Gases in Glass") of the International Commission on Glass (ICG). The present paper reports the conclusions of the final discussion, highlighting the issues on which consensus was reached (IR spectroscopy is suitable to monitor the water content; the water content of conventionally fired Containers is 300 to 400 ppm and daily oscillations are moderate; water, redox and sulphur interact mutually; water lowers the viscosity; the influence of water content variations on the radiative thermal conductivity is moderate) and the still controversial issues (influence of water and hydroxides in the batch on the final water content; influence of water in the batch and atmosphere on the redox State of the glass; influence of oscillations of OH level on the workability; influence of OH level on ease of forming, product quahty and strength).
- ItemThermal behaviour of glass batch on batch heating(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1992) Faber, Anne J.; Beerkens, Ruud G. C.; Waal, Henk deThe heating process of a barium-strontium glass batch has been studied in a 401 pot furnace, using a multiple thermocouple assembly. The effect of several batch batch parameters on the heating process has been measured, including layer thickness, cullet fraction, water content and pellets. The results have been evaluated using a heat penetration batch model. In the model two heating stages, below and above a certain batch transition temperature ϑs, typically 800 to 900 °C, are distinguished. Values for the temperature-dependent thermal diffusivity of the batch have been derived from experimental temperature distributions in the batch during heating. Below the thermal diffusivity has an almost constant value of 0.4 · 10^-6 m2/s for a standard (powder) batch blanket; for ϑ > ϑs the net thermal diffusivity strongly increases with temperature, due to the formation of primary melt phases. For ϑs < ϑ < 1100 °C the average value is about 1.4 · 10^-6 m2/s. Α 100 % cullet layer has a 50 % higher thermal diffusivity for ϑ < ϑs; pelletizing the batch is of little influence on the virtual thermal diffusivity and (extra) wetting has a retarding effect on batch heating due to extra heat absorption. As for the furnace temperatures it appears that increasing the temperature of the glass melt is more effective for improving the batch heating rate than increasing the temperature of the combustion chamber. Practical recommendations are given for batch preparation, charging and heating in industrial glass tanks.