Study on Photoacoustic Spectroscopy Detection of CO in Gas Insulation Equipment

Abstract

The related regulations for electric power industry stipulate that CO gas is an important component to be detected when analyzing the gas composition of SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> equipment. In this study, based on the photoacoustic spectroscopy technology, the quantitative gas detection of CO is carried out. First, in order to avoid the cross-interference effects of other component gases on photoacoustic spectroscopy detection of CO, the characteristic absorption spectrum of CO in 4291.5 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">−1</sup> (whose wavelength is 2330.2 nm) is determined. Second, the nonresonant photoacoustic cell is optimized in this study. After that, designing and building a trace gas photoacoustic spectroscopy detection platform around the developed photoacoustic cell, using the built detection platform to perform photoacoustic spectroscopy detection of the concentration of CO, and obtaining photoacoustic signals of different concentrations of CO, the photoacoustic signals increase linearly as the concentration increases. With SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> as the background gas, the lower detection limit of CO gas reaches 20.5 ppm, and with N <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sup> as the background gas, it reaches 5.6 ppm. After all, the influence mechanism of the background gas on the photoacoustic signal is studied, and based on the influence mechanism, the lower detection limit of CO with the background gas of different mixing ratios of SF <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sup> /N <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</sub> is predicted. The verified experiment is basically consistent with the predicted results, which proves the accuracy of the forecast. This study provides guidance for the engineering application of CO photoacoustic spectroscopy detection in SF <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">6</sub> equipment.