Ceramics-Silikáty 50 (4) 216-224 (2006)

The removal of one-component bubbles from glass melts in a rotating cylinder

L. Němec, V. Tonarová

The bubbles containing pure oxygen or carbon dioxide were investigated in a rotating cylinder containing glass melt. The equation of one component bubble with steady concentration gradient of gas on the bubble surface was applied, taking into account the effect of centrifugal force. The impact of the cylinder rotation velocity, the degree of its filling by the melt, cylinder radius, temperature, bubble size and bubble initial position in the cylinder on the bubble removal time from the melt was calculated with the aim to find theoretical advantageous conditions of the bubble removal process. Both mechanism of bubble removal, namely bubble dissolution and bubble separation to the cylinder centre, were found and evaluated. The mechanism preference depended primarily on the bubble initial composition. The dissolution mechanism was crucial for in glass well soluble gas as is oxygen whereas less soluble carbon dioxide exhibited only the mechanism of bubble separation. Both mechanisms were particularly accelerated by increasing the cylinder rotation velocity. The application of centrifugal fining needs the investigation of multicomponent bubbles with composition corresponding to bubbles under real melting conditions.

Keywords: Glass melt, Bubble, removal, Centrifugal force