Electric melting of glass

Abstract

The share of glass melted electrically is bound to rise steadily. Due to this situation many theoretical studies as well as practical developments have been conducted resulting in new interesting achievements. In the article the resistivity-temperature characteristics of different glasses will be shown. From their shape a criterion of stability of an electric furnace will be calculated. It will be pointed out that for the thermal stability not only the electrical but also the thermal properties of glass melt are important. Electric melting may also be stabilized by the proper distribution of energy in the basin of the furnace. The release of energy around the vertical rod electrode as well as the power density distributions within the glass bath for different electrode-pair configuration were modelled as well as calculated. Physical, mathematical and new type of modelling techniques were used for modelling the electric melting furnaces. The optimal connections of electrodes with the multiphase sources of power were found by the new type of modelling. The theoretical as well as practical problems concerning the corrosion of electrodes are being dealt with. Different ways of protection of electrodes against corrosion by glass melts are described. Furnaces for melting different types of glasses and new processes using electricity for melting are mentioned. The interest in electric melting of glass and its applications has substantially increased. It has a high thermal efficiency, is easy to control, yields homogeneous glass, economizes raw materials that volatilize readily and minimizes atmospheric pollution.