差分吸收光谱技术在工业污染源烟气排放监测中的应用

Measurement of industrial gas pollutant emissions using differential optical absorption spectroscopy

研究了差分吸收光谱技术在工业污染源烟气排放监测中的应用及实现.借助于独立的采样和前处理系统去除烟尘和水汽对光谱拟合的影响.为避免高浓度的SO2在常温下发生光解,将经前处理后的烟气加热至150℃进行测量.采用Voigt线型对SO2,NO,NO2在185—235nm波段的吸收截面进行了展宽,获得了高温气体的标准吸收截面,并与归一化的光谱仪仪器函数进行卷积得到了光谱拟合所需的有效吸收截面.将反演结果与非分散红外分析仪的测量结果进行了实时对比,获得了较好的一致性,验证了差分吸收光谱方法高准确度测量工业污染源烟气排放的可行性.

In this paper, we present a method of measuring the industrial gas pollutant emissions concentration by using differential optical absorption spectroscopy （DOAS）. The dust and water vapor which affect the spectrum fitting are filtered by the sample and pretreat- ment system. In order to avoid the photolysis of SO2 with high concentration, the pretreated smoke mixtures are heated to 150 ℃. In the process of DOAS retrieval, the reference absorption cross sections （185-235 nm） of SO2, NO and NO2 at high temperature are calculated by applying the Voigt broadening method to the original absorption cross sections at low temperature. The influences of temperature, pressure and instrument function are taken into account in the calculation. A validation study of SO2 and NO measure- ment is performed by comparing with the results measured by a non-dispersive infrared analyzer. The result shows that they are in good agreement with each other indicating that the DOAS technique has a potential application to industrial gas pollutant emissions measurement.