基于双差分的高精度甲烷浓度探测系统

Based on Double-Difference Precision Detection System for Methane Concentration

现有的甲烷浓度检测系统大多采用窄带激光器、可调谐激光器等实现对甲烷特征波长位置的对准,虽然可以有效提高检测精度,但高性能激光器价格昂贵、结构复杂,难以满足实际应用中需要小型化、便携化以及低成本的要求.据此设计了一种基于双差分的高精度甲烷浓度检测系统,设计了浓度差分转换窗口,可获取2组等效于窄带光对准的差分数据,从而实现了仅用宽带红外二极管作为光源的高精度甲烷浓度探测系统.分析了该系统的工作原理,推导了基于双差分的甲烷浓度函数,给出了双差分的算法流程.实验采用LSIPD型PIN光电二极管与C30659型红外探测器采集响应光强,利用GPro 500系列甲烷浓度检测仪作为标准检测设备对系统进行甲烷浓度检测误差分析.结果显示:当甲烷体积分数小于4.0%时,系统平均相对误差小于1.0%;当甲烷体积分数高于4.0%时,系统平均相对误差小于1.5%,验证了系统的可行性.

In the conventional methane concentration detection system, methane characteristic wavelength position was aligned used by narrow-band lasers, tunable lasers, and so on. It can be achieved effectively improve the detection accuracy, but the high-performance lasers are expensive, complicated. So this method can not meet the practical needs of small, portable and low-cost requirements. Based on double-difference the high precision methane concentration detection system was designed. Conversion window of concentration differential was designed, it can get the equivalent of two narrow-band optical alignment difference data. Precision detection system for methane concentration is implemented only used by broadband infrared diode as a light source. Working principle of the system is analyzed, and the concentration function of methane was derived based on dual differential, while the double-difference algorithm flow was given. In experiments LSIPD type PIN photodiode and C30659 infrared detectors were used to collect the light intensity response. There was error analysis of the system to detect the concentration of methane by GPro 500 series methane concentration detector as standard testing equipment. The results show that when the methane concentration is less than 4.0%, average relative error of the system is less than 1.0% ：When the methane con-centration is higher than 4.0% ,average relative error of the system is less than 1.5%. It verifies the feasibility of the system.