【作者】 周涛；

【导师】 孙长库；

【作者基本信息】 天津大学 ， 测试计量技术及仪器， 2009， 博士

【摘要】 大气污染是环境保护所面对的首要问题。作为大气污染气体的主要来源之一的固定污染源的烟气排放就成为监测和控制的重点。本文介绍了紫外差分吸收光谱法测量气体污染物浓度的基本原理和方法。并针对现场光谱测量中的准确性和测量精度的问题,在吸收光谱的特征提取、测量误差的拟合修正以及现场光谱的统计分析这三个方面进行了详细研究。主要内容包括：1.对形成紫外差分吸收光谱的电子光谱微观特性进行了研究。给出了经过实际光程中的散射和仪器响应特性等因素修正后的光吸收定律表达式。推导了理论模型中的背景光和吸收光谱与参考光和测量光谱之间的关系；2.在特征提取方面,在不同分辨率下采用能量因子筛选的方法进行加性噪声的去除,根据光谱间的时间相关性对吸收特征进行增强。并使用非线性多项式拟合的方法来减小实际测量条件和系统所产生的乘性噪声。现场数据证明,该方法显著提高了现场正常条件下的光谱信噪比,对现场监测数据的准确度提高有重要意义；3.在误差修正方面,采用光谱调理、吸收截面计算和不同吸收波段加权的三步修正法,包括光谱曲线的平移和拉伸；可用于现场和符合测量系统光谱响应的吸收截面计算方法；针对具有不同吸收波段的气体污染物,使用了高阶多项式波段加权的浓度拟合算法。这种方法将现场数据偏差降低到3%以下；4.为了近似地估计出现场光谱中氨法脱硫前后的主要成分比例及变化情况,分析了氨法脱硫的原理及生成的干扰物质。采用聚类和因子分析两种方法对现场氨法脱硫前后和实验室条件下的光谱进行对比研究。根据统计分析结论,使用分段拟合的方法对氨法脱硫的光谱进行计算,有效的提高了脱硫后数据的测量精度；5.研制了二氧化硫和氮氧化物的测量探头,并编制了气体光谱数据处理和分析软件。选择两个现场进行现场比对及实地运行试验。现场数据表明,监测系统能够适应现场的工业环境,实现稳定工作。更多还原

【Abstract】 Air pollution is the most important problem of the environmental issue. As the main source of air pollution, flue gas emissions have become the focus of the monitoring and control. In this article, the basic principle and measurement method of gas pollutants is introduced by differential optical absorption spectrometry (DOAS). The spectral feature extraction, the fitting method of the measurement error, as well as the statistical analysis of the scene spectrum are studied in detail. The main contents include:1. The micro-properties of the electric spectrum are described, which is the base of the differential optical absorption spectrum. The amended expression of the Lambert-Beer Law is given for the calculation ofDO AS. A variety of light-scattering properties of the actual light path and the functions of the equipment are taken into account in the formula. The relationship between the theoretical model of the background light and the absorption light, and the actual model of the reference light and measured light is deduced;2. In the aspect of feature extraction, a multi-resolution preprocessing method of original spectrum is adopted to denoise by the signal energy in different scales. On the other hand, the useful signal component is enhanced according to the signal correlation. In addition, the origin of the nonlinear factors is analyzed, that is caused by the actual measurement condition. And the polynomial approximation equation is taken to deal with it. This method improves the signal-noise ratio of scene nomal signal significantly;3. In the aspect of error correction, the three procedures of the spectrum conditioning, the computing of absorption cross-section and the absorption band-weighted, are adopted to amend the errors. This correction method includes the shift and stretching of the spectral curve, the calculation method of the absorption cross-section used for on-site and fitting the spectral function of the measurement system, the different weighted algorithm in the wavelength range for the measured gases that have different absorption wavelength range. The processed scene data error is lower than 3%;4. In order to estimate the main components ratio and changes of the spectrum before and after the ammonia desulfurization, the principle of ammonia desulfurization and the interference materials that may be generated are analyzed. The comparison between the spectrums captured in the lad and at the scene of desulphurization is taken with the help of the cluster and factor analysis. The calculation of the desulphurization spectrums is done by the use of the polynomial fitting in different sections, which increases the desulphurized data accuracy effectively;5. The sulfur dioxide and nitrogen oxides measuring probe is developed. The spectral data processing and analysis software is programmed. And two scenes are chosen to run and do the comparison tests. The on-site data show that, the monitoring system is suitable to the on-site industrial environment, which works stability.更多还原