High-Temperature Chemistry of Glass Furnace Atmospheres

The chemical nature of species in glassmelting furnace exhaust streams was thermodynamically analyzed using a computer program. These analyses indicate that the primary material which will condense out of such atmospheres is liquid sodium sulfate. It is postulated that the amount of sodium is controlled by equilibrium between the bath and the atmosphere. Given this assumption, higher sulfur contents decrease the sodium content, and higher chlorine increases the sodium content. Variations in the hydrogen‐to‐carbon ratio caused by using different fuels have only a modest effect on the condensation. Potassium behaves similarly to sodium but condenses at a somewhat lower temperature. It is believed that entrained dust particles serve as nucleation sites. The CaO and MgO particles derived from batch carryover and spalled refractories can be converted to the sulfate and dissolved in the liquid sodium sulfate, whereas the simultaneous presence of SiO2 can lead to a glasslike oxide mixture.