基于光纤耦合的紫外增强差分吸收光谱（DOAS）大气监测技术的研究

发布时间：2018-06-14 00:24

本文选题：大气污染 + 在线监测　；参考：《浙江大学》2015年硕士论文

【摘要】：随着社会经济的发展和生活水平的提高,大气质量越来越引起人类社会的关注。然而,随着工业和交通运输业的发展,城市大气污染日益严重。所以,我们需要找到一种有效的大气质量监测手段。差分吸收光谱技术(DOAS)在大气监测领域有巨大的潜力。针对现有DOAS大气监测系统紫外光强不足,信噪比不高等问题,本文研制了基于光纤耦合的紫外增强DOAS大气监测系统,并对系统进行了全面的性能测试。本文主要的研究内容如下：1、研究DOAS的原理,在掌握朗伯比尔定律的基础上,了解了米氏散射、瑞利散射以及其他消光因素的影响,引出了修正后的朗伯比尔定律。2、对现有DOAS大气监测系统的工作原理和特点进行了分析,在此基础上,提出了新式大气监测系统。该系统在光纤收发一体结构的基础上进行了改进优化,设计的收发一体望远镜主镜直径为20.1cm,准直发射的光在20m处光斑直径仅发散为24cm。采用紫外增强氙灯作为系统光源,光源系统采取了光纤耦合输出设计。对优化的DOAS系统进行了紫外光强外场测试,结果显示,单光程为135m下光谱仪积分时间仅为15ms时接收光强达到最大量程的80%以上。另外,相对于传统DOAS系统,新式DOAS系统具有灵活性、便携性等优点,而且更容易对光。3、研究并改进了DOAS技术的算法,使用Savitzky-Golay滤波拟合法取代传统多项式拟合法对吸收光谱进行慢变化拟合,提高了测量的准确性。4、采用SO2、NO2标准气体对系统进行了标定实验,实验结果表明,S02测量的最大误差为4.19%,NO2测量的最大误差为5.22%。5、利用系统对工业现场的大气污染物SO2、NO2、O3进行了连续监测并进行了对比分析,结果表明系统性能先进,完全满足雾霾等能见度低的天气下大气在线监测要求。
[Abstract]:With the development of social economy and the improvement of living standard, air quality has attracted more and more attention of human society. However, with the development of industry and transportation, urban air pollution is becoming more and more serious. Therefore, we need to find an effective means of air quality monitoring. Differential absorption spectroscopy (DOAS) has great potential in the field of atmospheric monitoring. Aiming at the problems of low ultraviolet light intensity and low signal-to-noise ratio of the existing DOAs atmospheric monitoring system, a UV-enhanced DOAs atmospheric monitoring system based on fiber coupling is developed in this paper, and the performance of the system is tested. The main contents of this paper are as follows: 1. The principle of DOAs is studied. On the basis of mastering Lamberbilt's law, we understand the effects of Michelson scattering, Rayleigh scattering and other extinction factors. The modified Lamberbilt's law .2is introduced, and the working principle and characteristics of the existing DOAs atmospheric monitoring system are analyzed. On the basis of this, a new type of atmospheric monitoring system is proposed. The system is improved and optimized on the basis of the integrated optical fiber transceiver structure. The primary mirror diameter of the integrated transceiver telescope is 20.1 cm, and the diameter of the collimated light is only 24 cm at 20m. The ultraviolet enhanced xenon lamp is used as the light source of the system, and the optical fiber coupling output design is adopted in the light source system. The external field test of the optimized DOAs system shows that the integration time of the spectrometer is only 80% of the maximum range when the integrated time of the spectrometer is only 15ms at the single optical path of 135m. In addition, compared with the traditional DOAS system, the new DOAs system has the advantages of flexibility, portability and so on, and it is easier to study and improve the algorithm of the DOAs technology. The Savitzky-Golay filtering method is used to replace the traditional polynomial fitting method to fit the absorption spectrum slowly, which improves the accuracy of measurement. Finally, the calibration experiment of the system is carried out by using so _ 2O _ 2 no _ 2 standard gas, so _ 2O _ 2 standard gas is used to calibrate the system. The experimental results show that the maximum error of S02 measurement is 4.19 and the maximum error of measurement is 5.220.The system is used to continuously monitor and compare the atmospheric pollutant so _ 2o _ 2no _ 2o _ 3 in industrial field. The results show that the system is advanced in performance. Fully meet the visibility of haze and other low visibility in the atmosphere online monitoring requirements.
【学位授予单位】：浙江大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X831

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