一种基于谐波检测技术的光纤甲烷气体传感器

甲烷是易燃易爆气体,是矿井瓦斯及天然气等多种气体燃料的主要成分.气体爆炸一直是困扰煤矿安全生产的重大难题,因此现场实时检测甲烷气体浓度对于工矿安全运行,人身安全有着至关重要的作用.基于甲烷气体近红外吸收的机理,研究了一种以DFB LD为光源的高灵敏度光谱吸收型光纤甲烷气体传感器.利用光源调制实现气体浓度的谐波检测,用二次谐波与一次谐波的比值来消除光路干扰.建立了谐波检测的数学模型,给出了甲烷气体的测量结果.利用光纤作为传光通道,使得探头可以与测量电?肥迪滞耆绺衾?增强了系统的安全性.

A Methane Gas Sensor with Optic Fiber Based on Frequency Harmonic Detection Technique

Methane is an inflammable and explosive gas and a major constituent of mine atmospheres, natural gas and gas fuels. Becuse gas explosion is a big problem in mining industry,real-time and on-line detection of methane has a critical function both for safety assessment and for control of combustion processes. Based on the mechanism near infrared spectral function both for safety assessment and for control of combustion processes. Based on the mechanism of near infrared spectral absorption of methane, a system using absorbent type optic-fiber for high sensitivity methane detection with DFB LD is demonstrated. Light source modulation harmonic measurement is presented in this paper. The ratio of the fundamental and second-harmonic signal presented can be used for eliminating optical interference. The mathematical model of gas concentration harmonic measurement is built up. The result of methane concentration is also shown. Optical fiber is used as transmission medium,thus the sensor part and measurement circuit can be isolated completely. The safety of the system is inhanced.