Features of Measuring Low CO Concentrations in N2-Containing Mixtures at Different Temperatures Using Spontaneous Raman Spectroscopy

Abstract

Raman spectroscopy is a promising tool for combustion processes optimization, due to the possibility of rapid determination of the exhaust gases composition. An important gas component in this task is carbon monoxide whose emission limits vary from 100 to 200 parts per million (ppm), depending on the heat generator technology. However, for the correct determination of its concentration from the sample Raman spectrum, it is necessary to take into account the contribution of nitrogen lines intensity due to their mutual overlap. This paper discusses a technique for deriving carbon monoxide intensity based on fitting the nitrogen spectrum at various temperatures. It is shown that ignoring the Herman–Wallis factors in the fitting procedure lead to an additional measurement error, which increases with temperature and exceeds 350 ppm at T = 1800 K.