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.