Chapter 13. Measurements of Sodium in an Oxygen-Natural Gas Fired Soda-Lime-Silica Glass Melting Furnace
- John Kieffer
Published Online: 26 MAR 2008
Copyright © 2000 The American Ceramic Society
A Collection of Papers Presented at the 60th Conference on Glass Problems: Ceramic Engineering and Science Proceedings, Volume 21, Issue 1
How to Cite
Buckley, S. G., Walsh, P. M., Hahn, D. W., Gallagher, R. J., Misra, M. K., Brown, J. T., Tong, S. S. C., Quan, F., Bhatia, K., Koram, K. K., Henry, V. I. and Moore, R. D. (2000) Measurements of Sodium in an Oxygen-Natural Gas Fired Soda-Lime-Silica Glass Melting Furnace, in A Collection of Papers Presented at the 60th Conference on Glass Problems: Ceramic Engineering and Science Proceedings, Volume 21, Issue 1 (ed J. Kieffer), John Wiley & Sons, Inc., Hoboken, NJ, USA. doi: 10.1002/9780470294598.ch13
- Published Online: 26 MAR 2008
- Published Print: 1 JAN 2000
Print ISBN: 9780470375662
Online ISBN: 9780470294598
- species vaporized;
- soda-limesilica glass melting;
Sodium species vaporized from melting batch and molten glass are the principal agents of corrosion of superstructure refractory and main contributors to emissions of particulate matter from soda-lime-silica glass melting in natural gas fired tank furnaces. The use of oxygen in place of air for combustion of the natural gas reduces particulate emissions, but has been associated with accelerated corrosion in some melting tanks. Methods for measuring sodium are under investigation as means for identifying its volatilization, transport, and deposition mechanisms and developing strategies for reduction of particulate matter emissions and corrosion. Three different methods were used to measure the concentrations of sodium species at various locations in an oxygen-natural gas fired soda-lime-silica glass melting furnace. Measurements were made in the combustion space using the obsorption of visible light by sodium atoms and in the flue duct using laserinduced breakdown spectroscopy (LIBS). Measurements in both the combustion space and flue were also made by withdrawing and analyzing samples of the gas and suspended particles.
LIBS has been under development at Sandia and at other laboratories as a technique for measuring parts-per-billion levels of metals in particles suspended in gas streams. The LIBS instrument, mounted on a stack, focuses the light from a pulsed Nd:YAG laser in the gas/particle mixture to be analyzed. The spark caused by electric breakdown at the focal point produces an emission spectrum in which the wavelengths of the spectral lines are characteristic of the elements present and the intensities of the lines are related to their concentrations. The LIBS instrument demonstrated its capability as a real-time monitor during 10 h of sodium measurements in the flue gas from the melting furnace. The mole fractions of sodium were in the range 60 ± 10 mol ppm. Potassium, magnesium, calcium, and silicon were also observed.
Concentrations of sodium atoms were measured in the combustion space of the same melting tank using the absorption of light by the sodium D-lines. Total sodium species concentrations were derived from the atom concentrations assuming local chemical equilibrium. The average total sodium mole fraction was 120 ppm, with higher and lower levels observed at the glass discharge and batch charge ends of the furnace, respectively. Using the measurement closest to the furnace exit, a value of 39 ± 15 mol ppm was expected at the sampling point in the flue, after accounting for dilution and the contribution from sodium in the flue gas quench water.
The levels of sodium measured near the furnace wall using the extractive sampling technique were typically 30 mol ppm, with a high value (173 mol ppm) observed in one corner of the furnace at the glass discharge end. In the flue, extractive sampling indicated a sodium mole fraction of 31 ± 16 ppm, in agreement with the value based on the absorption measurement in the furnace, but lower than the LIBS measurement at the same location in the flue.
The goal of the measurements is to elucidate the mechanisms of sodium volatilization, transport, and deposition; provide data for validation of numerical models; and identify operating conditions under which sodium volatilization can be minimized.