Field validation of a systematic approach to modeling of glass delivery systems

摘要

In the fiberglass production process, glass is produced from various batch ingredients in a glass furnace. The molten glass is then delivered, through a delivery system that is often called the front-end system, to the various downstream forming operations. Front-end systems consist of various covered channels and forehearths. One of the major tasks of a front-end system is to insure that the glass is conditioned to the stringent specifications required by the forming operations. Improperly designed and/or operated front-end delivery systems can cause a number of problems to the forming operations, ranging from poor conversion efficiency (resulting in waste generation) due to glass defects to shortened service life. In today's business environment, improvement in productivity, reduction in energy consumption, and minimization or elimination of waste generation have become priorities in managing and optimizing manufacturing operations. CFD has become an increasingly important tool for glass manufacturers to guide and optimize such system designs and operations. The current front-end model is developed to simultaneously simulate the chemically reacting turbulent flows in the superstructure and the laminar glass flow with strong buoyancy effects. Radiation from the superstructure wall surfaces and burner flames and internal radiation within the glass is modeled with the discrete ordinates (DO) radiation model in FLUENT. The turbulent reacting flow in the combustion space is calculated to obtain the flame shapes and lengths to accurately determine the heat transfer rate to the molten glass. The laminar glass flow, which is strongly influenced by natural convection, is calculated with temperature dependent physical properties. Simulations of the two radically different flow regimes are coupled through the interface boundary conditions in terms of temperature and heat flux continuity. Significant efforts were made to validate this approach with field measurements. Vertical temperature profiles were obtained in the glass melt as well as the combustion space at several strategically selected locations. The measurements were performed using two 6-element thermocouples housed in a platinum sheath. This coupled approach is expected to provide an effective tool that can be used to guide field operations as well as future system designs.