Abstract:

To meet the application requirements of real-time carbon dioxide (CO₂)-gas online monitoring, this paper proposes an online detection system for the CO₂ gas based on tunable diode laser absorption spectroscopy according to the theory of Beer-Lambert law. The selected absorption spectrum wavelength of the system is 1 609.583 nm. Futher, two reference optical paths are built to eliminate the signal fluctuation of the light source and automatically detect the absorption peak to improve the stability and accuracy of the detection system. The calibration of the system shows that the relative measurement error of the system is less than 0.8%, the system repeatability is less than 0.06%, and the response time is less than or equal to 18 s. Continuous monitoring of CO₂ in the air for 4 h shows that the fluctuation range of the volume fraction measurement is 360×10^-6 to 400×10^-6. The system has good stability and reliability and can meet the application requirements of real-time CO₂ gas online monitoring.

Key words: carbon dioxide, tunable diode laser absorption spectroscopy technology, gas detection, reference optical path