SO2 and SOF2 simultaneous detection by single mid-infrared laser based on tunable diode laser absorption spectroscopy

In the detection of multi-component gas based on tunable diode laser absorption spectroscopy (TDLAS), the problem of overlapping interference between the absorption lines of each gas is often encountered. For example, when detecting a gas mixture of sulphur dioxide (SO₂) and thionyl fluoride (SOF₂), the characteristic decomposition components of SF₆, there is overlapping interference in the absorption lines of the two gases, which makes it difficult to detect the concentration of gases accurately. In view of this problem, a novel method based on support vector regression model used for TDLAS is proposed to detect two gases simultaneously. The detection results show that the correlation coefficients between the concentration of SO₂ and SOF₂ and the average value of the second harmonic peak reached 0.992 and 0.993. In addition, through model testing, different concentrations of SO₂ and SOF₂ gas mixture are simultaneously detected, and the resulting maximum errors for measuring SO₂ and SOF₂ concentrations are less than 7.13 × 10⁻⁵ and 0.26 × 10⁻². The maximum errors of the measurement results in the verification test are not more than 6.4 × 10⁻³ and 4.6 × 10⁻². Therefore, with assistance of the novel method, the detection of multiple gases by using a single laser is achieved.