基于空分复用的矿井瓦斯浓度光纤检测网络研究

瓦斯爆炸事故频繁发生，对瓦斯浓度进行准确、实时检测和预警是治理瓦斯危害的有效手段。实验研究了基于气体光谱吸收原理，采用1.65 μm波长的近红外可调谐DFB激光器，利用激光器的模式跃变特性设计了差分吸收式的双波长单光路光纤传感网络。使用光开关并结合空分复用技术复用了16个瓦斯传感器，传感气室部分研究了防煤尘等关键技术。经PCI数据采集卡采集各路信号后，利用虚拟仪器对各路信息进行分析并显示。研究表明，在不采用数字锁相放大器，且气体吸收光程只有10 cm的条件下，探测灵敏度达到了0.05%，长时间的精确度和稳定性均可满足实际要求，各传感器切换响应时间小于1 s。该网络只要更换激光器就可对其他气体进行实时检测。

Fiber Monitoring Network of Methane Concentration Based on Space Division Multiplexing in Coal Mine

Methane explosion accidents occur frequently, and accurate and real-time detection and early warning of methane concentration are the effective means of preventing these accidents. The research was based on the spectrum absorption properties of methane, and a near-infrared tunable DFB laser diode of 1.65 μm wave band was used. With the mode-hopping features of laser diode, a differential absorption of double-wavelength and single-fiber optical sensor network was designed. Sixteen methane sensors were multiplexed in this system with space division multiple access technology and optical switch, and the key technologies of anti-dust in gas absorption cell were researched. All signals were gathered by the PCI data acquisition card，and information of each way was analyzed and displayed with virtual instrument. The results of experiment show that the method can reach the sensitivity of 0.05% even without using a phase-locked amplifier and the absorption light path is only 10 centimeters. Long-time accuracy and stability of all sensors could meet the practical demands, and the response time of each sensor was less than 1 seconds. With the replacement of lasers, the network can be used for the real-time detection of other gases.