Browsing by Author "Suwannathada, Pichanon"
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- ItemLocal temperature distribution and primary melt formation in a melting batch heap(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1994) Conrad, Reinhard; Suwannathada, Pichanon; Pimkhaokham, PreedaThe melting behavior of mass glass batches was studied in a gas-fired lab-scale furnace. Batches were adjusted to different redox numbers by additions of sulfate and coal. In each test, 4 kg of batch were charged onto a cullet melt (7 kg, 600 cm² surface area) which was pre-molten at 1200°C. The batch blankets had an initial height of approximately 5 cm. The vertical distribution of temperatures and electrical conductivides were recorded. The occurrence of primary melt was identified by a sudden increase of conductivity by three orders of magnitude. As expected, primary melt occurred latest in the inner zones of the batch. A comparison of conductivities and temperatures, however, showed that primary melt was not formed along any specific isotherm. Thus, the concept of a uniform melting temperature valid for the entire batch heap as used in several theoretical models is not confirmed. Thermal diffusivities derived from a numerical evaluation of the temperature field also displayed a sudden increase, however, at temperatures systematically higher than the temperatures of primary melt formation.
- ItemTracing of primary melt formation and reactions involved in glass batch melting(Offenbach : Verlag der Deutschen Glastechnischen Gesellschaft, 1997) Suwannathada, Pichanon; Hessenkemper, HeikoThe primary melt formation and the reactions involved therein were traced by means of electrical conductivity measurement. After the temperature of the furnace had reached 1200 °C, 700 g of soda-lime-silica glass batches, either with or without carbon addidon, were loosely charged into an induction furnace. An electrical conductivity sensor connected with a thermocouple was put immediately into the batch; then the conductivity in terms of voltage drop and the temperatures were continuously recorded. Not only the changes in t h e reaction atmosphere were detected, but also at least four events leading to the occurrence of the primary melts could be identified. They were the double salt (Na₂Ca(CO₃)₂) with a soda-rich NaCa mixed crystal eutectic, the sodium distilicate-silica eutectic, the double salt melting temperature, and the soda melting temperature. The temperature at which the conductivity curve passed its original baseline is proposed as the primary melt formation temperature. The first highest sodium ion diffusion rate, or hopping region on the conductivity-temperature curve, is also proposed as the primary glass-forming melt temperature.