New challenges are presented to the refractory materials in the crown and superstructure of oxy-fuel fired glass melting furnaces in comparison to air-fuel-fired glass melting furnaces. In glass melting furnaces that are oxy-fuel fired, the water steam partial pressure above the melt increases strongly. In the case of alkaline earth, alkaline-silicate glass melts together with the water steam partial pressure the alkaline hydroxide partial pressure increases with a factor of three in comparison to an air-fuel firing system. This leads to an aggressive action to refractory lining in the crown and superstructure. After extensive thermodynamic calculations and laboratory tests, a pure spinel refractory material (MgO.Al2O3) was developed for application in the crown and superstructure of oxy-fuel fired glass melting furnaces. The chemical and physical properties as well as the results of corrosion tests under oxy-fuel conditions of this direct-bonded, fused spinel material will be discussed. Because of its high corrosion resistance against alkaline attack and the spinel material can be proposed for successful application as crown and superstructure refractory for oxy-fuel-fired glass melting furnaces.
