Peter M. Walsh

Laser-induced breakdown spectroscopy at high temperatures in industrial boilers and furnaces.

Laser-induced breakdown spectroscopy (LIBS) was applied (1) near the superheater of an electric power generation boiler burning biomass, coal, or both; (2) at the exit of a glass-melting furnace burning natural gas and oxygen; and (3) near the nose arches of two paper mill recovery boilers burning black liquor. Difficulties associated with the high temperatures and high particle loadings in these environments were surmounted by use of novel LIBS probes. Echelle and linear spectrometers coupled to intensified CCD cameras were used individually and sometimes simultaneously. Elements detected include Na, K, Ca, Mg, C, B, Si, Mn, Al, Fe, Rb, Cl, and Ti.

Laser-induced breakdown spectroscopy of alkali metals in high-temperature gas

Laser-induced breakdown spectroscopy (LIBS) measurements of alkali in the high-temperature exhaust of a glass furnace show an attenuation of the Na and K LIBS signals that correlates with the stoichiometry of the bath gas surrounding the spark. The results are explained as being due to (1) a strong increase in the concentration of atomic Na and K, resulting in neutral line signal absorption by these atoms, and to (2) a change of phase of the major Na- and K-containing species from an aerosol to a gaseous phase when the gas mixture becomes fuel rich, resulting in a reduced LIBS emission intensity. LIBS sampling at lower temperatures, or in a consistently oxidizing environment, or both are suggested strategies for circumventing these difficulties.

Implications of air infiltration in oxygen/fuel fired glass furnaces

AbstractContinuous measurements of exhaust gas in an oxygen/natural gas container glass furnace show that diurnal variations in ambient air temperature produce significant changes in exhaust gas composition. At the highest ambient temperatures, the concentrations of air related species (O2, N2 and NO) are the lowest, while those of glass related species (e.g. SO2) are the highest. A detailed mass balance of the furnace shows that air infiltration may account for 30 wt-% of the total gaseous input to the furnace. The sensible heat associated with the N2 in the infiltrated air represents 6% of the total specific energy input. Therefore, reducing the amount of air infiltration can significantly improve furnace efficiency. As an alternative, when significant reductions in air infiltration cannot be readily achieved, a control strategy is proposed for the O2 flow into the furnace that considers the diurnal variations of infiltrated air flow. This strategy yields improvements in energy efficiency and furnace st...