Research on open circuit detection method of hydrogen sulfide/methane based on 8.309 μm QCL
The research of hydrogen sulfide(H2S)and methane(CH4)concentration measurement tech-nology is of great significance to petroleum and petrochemical industry.In this paper,a Quantum Cascade Laser(QCL)with a center wavelength of 8.309 μm was selected as the detection light source based on Tunable Diode Laser Absorption Spectroscopy(TDLAS)technology.A 30 m long distance sensing sys-tem was established by using Wavelength Modulated Spectroscopy(WMS)technology to measure the mixture of H2S and CH4 gases.The experiment mixed H2S with 5%volume fraction of water vapor for measurement,and it showed excellent absorption characteristics in this band,with less cross-interference.Through sensing experiments,the impact of different sensing distances of 15 m and 30 m on the detection signal was analyzed.By increasing integration time and calculating the signal-to-noise ratio,a minimum sensing limit of 128.75×10-9 m was achieved.Finally,Allan variance calculations revealed that when in-tegration time was 183 s and 142 s,the lowest detection limits for H2S and CH4 were 0.593×10-9 and 1.160×10-9,respectively.The results provide an effective method for remote measurement of highly sen-sitive H2S and CH4 multi-component gases and ensure safe operation in a variety of industrial environ-ments.
mid-infraredhydrogen sulfideQuantum Cascade Laser(QCL)multi-component gas sensing
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