Effect of Small Glass Composition Changes on Flue Gas Emissions of Glass Furnaces

Abstract

Relatively small changes in glass composition might have drastic consequences on the evaporation rates of volatile glass components in glass melting furnaces. Transpiration evaporation tests have been applied to measure the impact of minor glass composition changes on the evaporation rates of volatile glass components in simulated furnace atmospheres. The results of these laboratory evaporation tests were used to develop and optimize an universally applicable evaporation model to estimate evaporation rates and dust emissions for industrial glass melt furnaces. Mass transfer relations for the transport of volatile glass melt species into the turbulent gas phase were used to upscale the evaporation models valid for the lab tests to applications for industrial glass furnaces. In this paper, the impact of sulfur and chlorides on the evaporation rates of sodium and potassium from multi-component silicate melts for industrial glass production will be demonstrated.

Dynamic high‐temperature crystallization and processing properties of industrial soda–lime–silica glasses

“…On the other hand, the calculated equilibrium constants of sodium evaporation reactions (specifically the formation reaction of NaOH) from silicate glasses were 7.16 × 10 −2 and 4.17 at 1000 and 1400 • C, respectively. 41 Beerkens 42 similarly noted that sodium volatilization reaction kinetics at 1500 • C are at least two orders of magnitude higher than at 1000 • C. This suggests that whilst some level of alkali volatilization will have occurred during the extended experiments in the present study, the degree of volatilization should be minimal because the rate of sodium evaporation from silicate melts at the temperatures at which the extended experiments were conducted is orders of magnitude smaller than that at higher melting temperatures. At the liquidus temperature position, our microscopic examination of the C 3 glass in the liquidus boat showed that columnar and bladed structured wollastonite-2M crystals exhibited no change in their structural characteristics in the bulk of glass, on the surface of the glass melt and at the interface between the glass and the boat.…”

“…In the case of significant alkali volatilization, the relative concentration of CaO could notably increase and would significantly influence the type of crystal formation. 41 This effect may manifest as a shift toward different wollastonite polymorphs within the studied compositional range of the soda-lime-silica glass melts. However, the HTXRD patterns obtained during the 30 × 30 min scans at 800 and 900 • C show no such behavior and do not support the hypothesis of any noticeable shift in the primary phase fields to wollastonite polymorphs that could be associated with alkali volatilization.…”

“…Consequently, the possibility of any significant levels of alkali volatilization from the interior (bulk) T-and Cgroup glasses during the extended experiments can be discounted. However, XRF analysis of the heat-treated bulk glass samples may not accurately represent the composition of an alkali-depleted thin surface layer that could form during an extended period of heat treatment 41,42 as this thin surface layer may not measurably influence the overall or bulk glass composition. On the other hand, the calculated equilibrium constants of sodium evaporation reactions (specifically the formation reaction of NaOH) from silicate glasses were 7.16 × 10 −2 and 4.17 at 1000 and 1400 • C, respectively.…”