Browsing by Author "Wilsmann, Wolfgang"

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    Low Pressure evaporation from boron containing glass melts by the transpiration method
    (Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 2004) Dacko, Dawid; Wilsmann, Wolfgang; Conradt, Reinhard
    Glass melting is a well-established process, but it does not seem to be well understood under low-pressure conditions. Melting under low pressure has been suggested as a potential support of the refining process. This makes sense only if the evaporation form the glass melt is kept within acceptable limits. A transpiration apparatus equipped for operation at low pressure, termed low pressure transpiration method, was used to investigate the evaporation from boron containing glass melts. We obtained information on the weight loss as a function of temperature, time, and pressure. We investigated an alkali borosilicate glass with acomposition in mol % of: 79SiO₂,7 Na₂O, 10 B₂O₃, 3 AI₂O₃, 1 minor constituents. At the beginning of glass melting, the evaporation mechanism was detected as surface controlled. Later, a diffusion controlled stationary behaviour was observed. The ratio of sodium oxide to boron oxide in the evaporated gas as determined by chemical analysis ranged from 1.25 to 1.4.
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    Thermochemistry of the glass melting process - Energy requirement in melting soda-lime-silica glasses from cullet-containing batches
    (Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1996) Madivate, Carvalho; Müller, Franz; Wilsmann, Wolfgang
    The theoretical energy requirement in meldng flat and Container glasses of the soda-lime-silica type from corresponding batches was directly measured at temperatures from 1370 to 1700 Κ using the drop-mixing method. In addition, the energy to be expended in headng the aforemendoned glasses, as well as calumite and ecomelt, from ambient temperature into the ränge from 1080 to 1700 Κ was determined using transposed-temperature drop calorimetry. Guided by the results, thermochemical methods proposed in the literature for the estimadon of the theoretical energy demand are critically assessed. Furthermore, the measured data are combined with information taken from thermochemical tables to derive the enthalpy effects contributing to the total enthalpy change associated with the conversion of the considered glass batches into the corresponding glass melts. On the basis of the information obtained, the ways in which the theoretical energy demand could be reduced are discussed. The influence of additions of cullet and other raw materials, such as calumite and spodumene, on the theoretical energy requirement is investigated, and the energy saving through additions of these materials is estimated.