No abstract

No abstract

An ir analyzer employing gas-filter correlation techniques has been designed and constructed to measure the concentrations of CO, NO, SO(2), HCl, and HF in the stacks or ducts of stationary pollutant sources. Use of a retroreflector allows the stack to be double passed, and no sample is extracted. For each gas, small interchangeable fixed-position grating polychromators are used as narrow (~1.5-cm(-1)) multiband spectral filters with the bands corresponding to locations of selected absorption lines. The approximate useful ranges (in parts per million-meters) over which this analyzer operates are 10-4000 for NO, 10-1500 for CO, 50-40,000 for SO(2), 10-2000 for HC1, and 5-200 for HF. The discrimination against other gases and particulates is excellent. The analyzer has been tested in the laboratory and on a variety of pollutant sources.

A commercial Fourier transform interferometer system with telescopic optics has been installed in a van and used to make long-path absorption and single-ended emission measurements of gaseous pollutant concentrations at a number of geographical locations. The system covers the IR spectra region from 650 cm(-1) to 6000 cm(-1) at a maximum resolution of 0.06 cm(-1). For many pollutants, concentrations in the 1-10-ppb range can be detected over a 1-km path length. To date, measurements have been made in the absorption mode across fertilizer plant gypsum ponds, an oil refinery, and jet engine plumes; industrial stacks, waste gas flares, and jet engine plumes have been studied in the emission mode.