APPLICATION OF FT-IR ABSORPTION-SPECTROSCOPY FOR IN-SITU GAS CONCENTRATION AND TEMPERATURE-MEASUREMENTS IN LABORATORY-SCALE AND PILOT-SCALECOMBUSTION ENVIRONMENTS

In situ FT-IR absorption spectroscopy was used as a diagnostic tool to evaluate the gas phase above a heterogeneous reaction, black liquor c har combustion. Previously developed calculation methodologies were us ed to determine the CO and CO2 concentrations and the CO rotational te mperatures from absorption spectra. Spectroscopically obtained gas tem peratures and concentrations from laboratory-scale experiments were co mpared to thermocouple and NDIR measurements. Quantitative evaluations of the gas phase during these experiments indicated that gas temperat ures can be measured with an accuracy of 2-3% at 450 750 K and gas con centrations can be measured with accuracies of better than 10% at gas concentrations between 0.3 and 1.3%. Gas temperatures obtained during pilot-scale combustion were between 1118 and 1183 K, while concentrati ons were between 0.35 and 0.76%. Differences among gas concentrations and temperatures calculated from the absorption spectra, compared to N DIR measurements and thermocouples, were greater than those from labor atory combustion due to the dynamics of the gas phase. The need is exe mplified for a well-characterized combustion environment for effective use of FT-IR as a diagnostic tool for pilot-scale combustion and for advancing the fundamental understanding of combustion processes.