Industrial Stack Evaluation With Ground-Based Passive FT-IR Spectrometry

The methodology for producing absorbance and transmittance spectra with a passive Fourier transform infrared (FT-IR) spectrometer from an industrial stack and blackbody source is demonstrated. The knowledge of the stack temperature is shown to be key in generating the single-beam spectral ratio of differences for removal of instrumental effects from the absorbance and transmittance spectra. The difference removes self emission (i.e., offset) terms, and the ratio eliminates the responsivity (i.e., gain) term. The experimental procedure for acquiring the interferograms and single-beam spectra is documented. The experimental results that are obtained for three types of industrial stack are presented in the form of summary graphs and tables. Representative spectral data are also furnished in the Appendixes. Stack target analytes in the study are sulfur dioxide, nitrous oxide, and ammonia.