Ultra-low flue gas emission monitoring based on differential optical absorption spectroscopy

This paper describes a set of ultra-low smoke emission monitoring optical devices based on differential absorption spectroscopy (DOAS), which mainly includes a xenon lamp source, a sample cell, a spectrometer for light detection, and a Y-type optical fiber. The device utilizes a newly developed ultraviolet long path gas chamber, the energy of the ultraviolet spectrum is high, and the energy of the xenon lamp in the experiment is only enough to meet the application requirements. As well, based on DOAS optical device it has the advantages of high ultraviolet energy, small volume and high measurement accuracy. Therefore, the system solves the difficult problem of low concentration flue gas emission monitoring. The lower limit of detection of SO₂, NO and NO₂ concentration was 0.21 mg/m³, 0.13 mg/m³ and 0.61 mg/m³, respectively. Comparison of on-site field monitoring with high temperature FTIR (Fourier Transform Infrared Spectroscopy) flue gas emission monitor, the average concentrations of SO₂, NO and NO₂ measured by the two instruments were less than 14 mg/m³, 39 mg/m³ and 25 mg/m³ respectively, and the correlations were all above 0.995.