基于特征吸收光谱的甲烷气体浓度静态检测方法研究

根据甲烷气体的吸收光谱设计了井下甲烷实时检测系统。在分析甲烷气体对应的特征光谱吸收波长的基础上,采用静态傅里叶变换干涉具和线阵CCD探测器,在对干涉条纹进行傅里叶变换后得到光谱信息,从而求出各波长上的光强衰减量。通过仿真实验,计算了瓦斯浓度关于光源光强、出射光强的函数关系,选择了10mW的激光器。根据比尔-朗伯定理及浓度程长积公式,给出了甲烷浓度的表达式,检测系统的最小探测浓度为0.02%,可满足井下甲烷浓度0%～5%的范围及0.10%的精度要求。实验证明,采用傅里叶变换光谱分析法求解甲烷浓度可达到井下实时监测的要求。

Study on Static Detection of Methane Concentration Based on Characteristic Absorption Spectrum

A real-time detection system of methane concentration for mine was desiged according to the characteristic absorption spectrum of methane.Based on the analysie of wavelength of the characteristic absorption spectrum of methane,static Fourier transformation interferometer and linear CCD detector were adopted to obtain the spectral information,sequentially,the attenuation decrement of luminous intensity of the spectrum with different wavelengths was calculated.By simulation computation,the functional relations of the intensity of incident light and outgoing light with methane concentration were present out,on these grounds,a laser with power of 10 m W was adopted to the real-time detection system.A expression of methane concentration was given out based on Lambert-Beer theorem and concentration-path length product formula.The least detection concentration of methane for the real-time detection system is 0.02%.The detection system can meet the demand of detecting mine methane with the concentration of 0 to 5% and the detection precision of 0.1%.The experiments proved that using Fourier transformation spectroscopic analysis to solve methane concentration can meet requirement of real-time detection of mine methane.