Ceramics-Silikáty 50, (3) 140 - 152 (2006)

The separation of melting and fining processes during glass melting requires the detailed examination of fining space geometry and glass flow character inside the space. This paper deals with removal of single bubbles in horizontal and vertical channels with different character of glass flow. The fining performance of the channel producing no bubble defects is the followed technological quantity. The model glass is the glass for production of TV bulbs, the experimentally measured bubble growth rates were used to evaluate the fining process. To appreciate the impact of glass flow character in a given channel on the fining efficiency, the relations valid for the process in channels with plug flow were derived and the numerical model was applied. The results have shown that channels with plug flow or flow with the parabolic melt velocity profile are most efficient. The appropriate geometry of the channel may be estimated from simple relations governing the fining performance of channel with plug flow.