Detailed comparison of physical fining methods in an industrial glass melting furnace using coupled CFD simulations

Melting and primary fining represent the most essential steps in the glass manufacturing process. Electric boosting and bubbling are common methods used to optimize these processes by improving the product quality and energy efficiency. However, a structured overview of their impacts on the operation of the total melting furnace has not previously been published. The present paper provides a thorough comparison of these technologies applied to an industrial melting furnace, including the effects on temperatures, melt flow patterns, glass quality, as well as the heat fluxes and process efficiency. In this work, extensive numerical simulations were performed. Unlike other studies described in the literature, a validated CFD model of exceptionally high accuracy was employed. Furthermore, the entire melting furnace was considered, such that the glass tank was coupled to detailed simulations of the turbulent gas-phase combustion. A novel method for combustion modeling in glass manufacturing was applied, and user-defined functions supported an analysis of glass quality. Substantial differences were observed between the furnaces with electric boosting and bubbling. For the first time, interrelated effects could be described in detail, providing a comprehensive overview of the entire operation. Based on the presented results, the targeted use of both electrodes and gas nozzles is suggested for future melting processes.