Investigation of the bottom and throat current in a glass melting tank with drainage of contaminated bottom glass

Abstract

In glass melting tanks the formation and/or enrichment of contaminations in the bottom area may occur. By methods of melt circulation and the insertion of drainages it is tried to prevent these contaminations in production glass. The occurring processes, however, are difficult to investigate on real tanks. It is also difficult to carry out a change in the tank design during its operation. Therefore, a mathematical model for the glass melting tank was developed calculating the flow and the temperature distribution in a vertical section. The calculations were carried out for fuel-heated tanks. The result of the drainage and the behavior of the slush (= contaminated bottom glass) were investigated with several variants. It showed that the behavior of the slush is strongly dependent on its layer thickness. From the investigations a submerged drainage proved to be the best solution. Drainage should be positioned in front of the throat or in the throat directly. The insertion of a second submerged drainage in the dead region of flow in the fining tank is favorable.