基于静态干涉系统的井下甲烷浓度实时监测系统的研究

为了保证井下工作安全,设计了一种CH4实时在线监测系统。在分析了CH4气体特征吸收光谱的基础上,系统采用静态傅里叶变换干涉具及柱面镜等组成。通过线阵CCD采集静态干涉条纹,由光谱分析算法求出各个波长上的光强衰减度,最后通过比尔-朗伯定理、浓度程长积公式等反演CH4气体的浓度。仿真计算了光源光强、出射光强与瓦斯浓度的函数关系,验证了采用5 m W的DFB激光器,可以保证变化区域基本线性。系统采用分子筛过滤处理的方法,克服了目前光谱检测系统无法在井下复杂环境应用的难题。实验显示,在5 cm的气室中,经分子筛过滤保护的光谱探测系统可以在潮湿、粉尘的环境中稳定工作。采用傅里叶变换光谱分析法求解CH4浓度时,最小探测精度可达0.01%。

Research on CH4 Concentration Detection System in Mine based on Static interferometer

In order to ensure the safety of work in mine, designed the online monitoring system for a low concentration of CH₄ in mine. According to analyze the absorption spectrum of CH₄ gas, the system composed Fourier transform interferometer, cylinder, and so on. By linear array CCD acquisition static interference fringes, solved spectrum intensity of various wavelengths, at last, calculated CH4 gas concentration by Bill-Lambert theorem, concentration path formula, and so on. Simulation of gas concentration function with the light source intensity and the outgoing light intensity, verified using 5mW DFB lasers can guarantee the basic linear change in the region. The system uses the method of molecular sieve filter, dealt with the problem that the spectrum detection method is hard to apply in complex mine environment. Experiments show that in the 5cm gas chamber by molecular sieve filter the system can work in moisture, dust stable environment. Using Fourier transform spectrum detection method to calculate CH₄ concentration, the minimum detection accuracy can reach to 0.01%, so it can prove that the system can detect the CH4 concentration in mine in effect.