Near-Infrared Spectral Analysis of Gas Mixtures

Abstract

The analysis by near-infrared spectroscopy (NIR) of a series of gas mixtures approximating natural gases is reported. Wide variations of gas pressure and temperature are used in accord with conditions found in various utilitarian gas flow streams. The NIR analysis of CH4 and CO2 composition is found to be straightforward and depends only on compound mass density, but not explicitly on temperature, pressure, or composition. Linearity of the spectra of more complex mixtures is maintained, but the NIR analysis is more complex. Principal component analysis is shown to resolve composition for those gas mixtures.