The sprung arch that roofs a glass melting tank, a reheat furnace or a regenerator chamber. Glass furnace crowns are usually silica brick: it carries load almost to its melting point, and silica that drips into the melt dissolves without leaving defects. Oxy-fuel furnaces often use alumina or AZS instead, because alkali vapors attack silica and eat channels called rat holes. Crown temperature limits how hard the furnace can be fired.
Crown is at 1590, that's the limit for silica, back off the burners on port 3.
Also heard as
- roof
- furnace crown
- arch
Related terms
Silica brick
Brick of over 93 percent silica with high hot strength but sharp volume changes when cooled below red heat.
Skewback
Angled brick or support course from which a sprung arch springs and pushes its thrust into the steelwork.
AZS
Alumina-zirconia-silica fused-cast refractory, the standard glass-contact material in glass melting furnaces.
Doghouse
Small extension on a glass melting furnace where the batch is charged into the tank.