Quantitative analysis of SO₂, H₂S and CS₂ mixed gases based on ultraviolet differential absorption spectrometry

SO₂, H₂S and CS₂ are the decomposition components of insulating gas SF₆. The detection of these gases is significant for the online monitoring and fault diagnosis of SF₆ electrical equipment. In this study, an ultraviolet differential optical absorption spectrometry (UV-DOAS) platform for detecting the concentration of SO₂, H₂S and CS₂ mixed gases was established and a quantitatively detecting method was proposed. Firstly, the concentration of SO₂ was calculated by the spectrum data at 300 nm band. Then the gas mixture spectra of H₂S and CS₂ at 200 nm band were obtained after linear deduction of SO₂ spectrum. By wavelet extraction and fourier transform, the spectral information of H₂S and CS₂ was separated and the concentrations of the two gases were calculated. The method can detect the concentrations of SO₂ (1-20 ppm), H₂S (1-20 ppm) and CS₂ (0.01-2 ppm) ternary gas mixture and the detection limits of SO₂, H₂S and CS₂ are 0.44 ppm, 0.49 ppm and 3.23 ppb. This method has good detection sensitivity and high detection precision, which is suitable for the on-line monitoring of SF₆ gas insulated equipment.