Oxy-gas forehearths: results of mathematical modeling of a flint glass and field trials on a borosilicate glass

摘要

This paper describes the results of mathematical modeling, burner development, and field trials carried out with oxy-gas forehearths. Mathematical modeling was carried out for the rear cooling section of a BH-F forehearth conditioning a flintglass. The modeling coupled the glass channel with the forehearth combustion space. The glass exit temperatures from this section were compared under both air-gas firing and oxy-gas firing. Results indicated that for the same glass flow rates, cooling was more efficient in the center of the channel and heating was more efficient close to the sides under oxy-gas firing. The combined effect was a 30% improvement over air-gas firing in temperature spread at the exit of the cooling zone. Conversely, the modelalso predicted that for similar temperature spreads, oxy-gas firing would allow the pull through the forehearth to be increased by 30%. Special very low-flow oxy-gas burners have been patented for use in forehearth applications. This includes the mantleblocks, quarls, and burners for side-channel applications and bowl/spout applications. A forehearth for the production of borosilicate glass lighting components was successfully converted to oxy-gas firing in 1996. This was done to overcome the problemsexperienced with air-gas firing. Oxygen-gas firing, by reducing the volume flow of combustion gases and increasing the available heat from the fuel, leads to increased output, improved glass quality, and lengthened refractory life. This paper describesthe changes made to the forehearth and the improvements gained in the glass conditioning process. In September 1997, the melter was repaired and the opportunity was taken to make further improvements to the forehearth.