基于差分吸收的H2S气体浓度检测系统

H2S Gas Concentration Detection System Based on Differential Absorption

石油和天然气开采过程中,H2S气体浓度很低,很难精确检测,直接吸收检测H2S的方法虽然容易实现,但是由于光源不稳定,检测精度偏低。文中采用差分检测系统检测H2S气体浓度,并介绍该系统的基本原理,建立了H2S气体检测的数学模型。整个系统采用LED作为光源,为提高检测精度,先将光源输出的光波进行滤波。然后采用差分吸收检测方法,用光纤布拉格光栅进行滤波和调制,得到2种不同波长的光源,通过锁相放大技术得到2个幅值信号。将2个幅值信号相除得到H2S气体浓度检测的仿真结果。结果表明,光纤光栅滤波与差分吸收检测系统相结合的方式,减小了由温度不稳定、光源波动、光路强弱等引起一系列误差,提高了检测气体的精确度。

During oilandgas extraction the concentration of H2S gas is very low and it is difficult to detect accurately,The method of directly absorbing and detecting H2S is easy to implement,the detection accuracy of the method is low because the light source is unstable.In this study,the differential detection system was used to detect the concentration of H2S gas,and the basic principle of the system was introduced.The mathematical model of H2S gas detection was established.The whole system used LED as the light source.In order to improve the detection accuracy,the light wave output from the light source was first filtered.Then,the differential absorption detection method was used to filter and modulate with fiber Bragg grating to obtain two different wave⁃lengths of light source,and two amplitude signals were obtained by phase⁃locked amplification technology.The two amplitude sig⁃nals were divided to obtain a simulation result of the H2S gas concentration detection.The results show that the combination of fi⁃ber grating filtering and differential absorption detection system reduces a series of errors caused by temperature instability,light source fluctuation,optical path strength,etc.,and improves the accuracy of detection gas.