| Sulfur dioxide（SO2）has a toxic and pungent odor,can produce acid rain,damage the environment,and cause serious pollution to the atmospheric environment.Methane（CH4）is a greenhouse gas second only to carbon dioxide,and the reduction of methane has attracted global attention.Obtaining the spatial distribution of concentration and emission flux of pollution sources is of great significance to my country’s air pollution control and the realization of the"dual carbon"goal.Differential absorption lidar is one of the most mature technologies for measuring the spatial distribution of concentration.Due to the characteristics of spatial resolution and wide measurement range,the research on spatial concentration distribution and emission flux measurement of differential absorption lidar is one of the urgently pursued technologies for air pollution control and the realization of the"dual carbon"goal in my country.Under the current background,this paper conducts basic research on the spatial distribution of concentration and emission flux measurement of differential absorption lidar.Based on the principle of differential absorption lidar concentration detection,combined with the scanning angle,the concentration distribution and emission flux measurement models were studied;taking the differential absorption coefficient,a key parameter of concentration detection accuracy,as the research object,the SO2 and CH4 absorption spectra were analyzed and measured in detail,and the established The key parameters of the concentration measurement of this system;the lidar return signal is processed accordingly,and the concentration is determined.Inversion algorithm,and then inversion of quantitative concentration optical path value and atmospheric pollutant concentration;built an external experimental platform,and used a controllable gas release device to simulate point source emissions to achieve differential absorption lidar concentration distribution and emission flux measurement and inconsistent.Certainty evaluation.The main research results of this paper are as follows:1.Optimized the differential absorption coefficient of SO2 and CH4 measurement of differential absorption lidar.Based on the Hitran spectral database and taking into account the interference of other gases in the atmosphere,the spectral parameters suitable for this system were selected and the differential absorption coefficient of the gas to be measured was corrected.The differential absorption coefficientsΔαSO2=2.41ppm-1·km-1 andΔαCH 4=0.455ppm-1·km-1 were determined by precise spectral scanning using a standard gas cell.2.The spatial concentration distributions of SO2 and CH4 were measured experimentally by using the ultraviolet-infrared dual-band differential absorption lidar system.The spatial concentration distribution is obtained through spatial scanning,and the measurement results show that the position of the emission point located through the concentration distribution measurement is within 10 m of the actual emission source position,which realizes the accurate spatial positioning of the emission source position.3.A point source controllable gas release device was built.The experimental verification of emission source concentration distribution and emission flux measurement based on differential absorption lidar technology is realized.By building a point source SO2 and CH4gas emission field experimental device,the differential absorption lidar is used to realize the measurement of the concentration distribution in the target area and the inversion calculation of the emission flux measurement.The measurement results show that at the emission rate of0.12 kg/h,the measurement result of SO2 emission flux is 0.11 kg/h,the expanded uncertainty is 19.26%,the CH4 emission flux is 0.12 kg/h,and the relative error is-7.7%. |
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