Based on tunable semiconductor laser absorption spectroscopy(TDLAS)and frequency division multiplexing(FDM)method,a near-infrared multi-component trace gas identification and detection system based on support vector machine(SVM)classification was studied.When laser spectroscopy technology characterizes gas absorption spectral lines,the absorption capacity of gas in the near-infrared band is lower than that in the far-infrared band.The absorption signal of gas detected by single-band laser spectrum is weak,and each gas component interferes with each other greatly.To improve detection accuracy,accurately identify gas components and perform multi-component detection at the same time,based on tunable semiconductor laser absorption spectroscopy technology,the frequency division multiplexing near-infrared TDLAS technology method is used,and the SVM classification algorithm is used to perform the real-time detection process of mixed gases.It effectively avoids cross-interference of various gases and realizes trace detection of eight gas markers:nitric oxide NO,hydrogen sulfide H2S,ammonia NH3,nitrogen dioxide NO2,acetylene C2 H2,carbon dioxide CO2,methane CH4,and hydrogen chloride HCl.When eight lasers work simultaneously,the system controls the band-pass filter to perform time-sharing filtering.It sequentially transmits the second harmonic data after differential phase locking to the host computer for real-time display.The recognition rate is over 96.3％,and the average content prediction accuracy is higher than 99.6％.It has achieved high-precision detection results with the lowest detection limit of CH4 being 0.01 μL·L-1,NO2 being 0.05 μL·L-1,and C2 H2 being 0.03 μL·L-1,and the detection limits of other gases are below 5 μL·L-1.Conduct anti-interference analysis and detection lower limit analysis on the multi-channel detection of the system to verify that the system can achieve high-precision concentration detection of mixed gases when the system is operating stably.This system uses a distributed feedback laser drive and lock-in amplifier combined with the SVM algorithm model of data processing to realize multi-component trace gas identification and detection of near-infrared TDLAS technology,which can meet the trace level detection of trace gases and provide ultra-low performance for the future.The detection of concentration mixed gases is of very important significance.
关键词
可调谐半导体激光吸收光谱/频分多路复用/支持向量机/混合气体探测
Key words
TDLAS/Frequency divisionmultiplexing/Support vector machines/Mixed gas detection
维普
万方数据