Research On Remote Sensing Of Methane Based On Tunable Diode Laser Absorption Spectroscopy Technique

With China's energy situation and atmospheric pollution situation severely, as much more attention has been paid on the development of gas pollutant detecting technology. Tunable diode laser absorption spectroscopy (TDLAS) is developing very rapidly as one of the representative measurement method, with features of high sensitivity and fast response. Early research about TDLAS mainly focuses on the parameters, such as concentration, temperature and velocity through the gas absorption in experimental cell. But the research about practical application that an approach of open-path gas sensor based on TDLAS of telemetry is scarce.This paper based on the telemetry telescope transceiver systems which combined the detector and laser located in the same equipment is to develop the method of on-line remote sensing for gases. The systems not only save space and cost, but also facilitate the field application.This paper expounds the measurement principle of TDLAS, including involving molecular absorption spectroscopy. Introduce the experimental platform and related equipment. Firstly, detecting nine different concentrations of CH4 in the laboratory, respectively using direct absorption method and wavelength modulation spectroscopy method. Then analyzed the data and compared the advantages and disadvantages of between the two ways. Secondly, on the basis of the above experiments'results, a remote sensing telescope transceiver system is utilizes to gradually measure the gas concentration. Trials of on-line monitoring of CH4 are divided into three steps. The purpose of the first part is to test the performance of telescope transceiver system. The result shows the system has appropriate stability and accuracy. The second part is to put into use the telemetry telescope transceiver system to detect CH4 concentration in-situ. The data record the trend that second-harmonic signal changes with time.The paper put forward an solutions about remote sensing of gas leakage which based on tunable diode laser absorption spectroscopy technology. Then build test-bed, repeatedly validate the stability and precision of experimental system, analysis and compare the results in the different conditions. The data shows that detecting concentration and standard concentration are consistent, their linear correlation coefficient is greater than 0.99. This paper proposed a remote sensing method that has good accuracy and practicality, it can be extended to other gas detection.