Diode laser-based photoacoustic spectroscopy detection of acetylene gas and its quantitative analysis

Abstract

SUMMARY Acetylene in oil is an important characteristic gas which reflects early discharge faults of transformer and other oil-immersed electrical equipment. Laser-based photoacoustic spectroscopy techniques of high sensitivity and good selectivity can be well applied to detect trace gases. A portable and tunable experimental setup with a distributed feedback diode laser has been developed in this paper. The photoacoustic cell property parameters, the relationships between the photoacoustic signals and the laser power and the acetylene gas concentrations were analysed experimentally. By means of diode laser wavelength modulation, the high-resolution acetylene photoacoustic spectrum near 1.5 µm in the first overtone band near infrared was investigated. A novel method of photoacoustic quantitative analysis was proposed on the basis of least square regression. The theoretical and experimental results show the feasibility of on-line monitoring of acetylene and designing a tunable photoacoustic spectrometer with high sensitivity. Copyright © 2011 John Wiley & Sons, Ltd.