The all-electric glass melter represents a melting technology suitable for lower pull, high liquidus temperature glasses and/or glasses with high volatilization rates. Borosilicate glass type is one of those glass compositions typical molten in an all-electric melter. Advantages of the application are the cold batch cover of the melt suppressing most of the evaporation and the direct heat transfer from the electrodes into the melt. The general problems of the all electric melting technology are the fining conditions and the degassing of the melt. In case of the borosilicate type glass the low solubility of the sulfur requires careful design of the furnace itself and almost constant process conditions. Investigations on sulfur solubility in borosilicate lasses have been performed and are well described in the literature. Based on these results it can be shown that the electrode configuration immersed from top through the batch results in better degassing conditions compared to the configuration with bottom electrodes. This approach is in accordance with a number of patents taken out by different inventors addressing the sensitive flow and degassing conditions of this type of melter. CFD simulation model tests results are given for the different design solutions. The results confirm the beneficial conditions achieved by the top electron configuration.
