Method for measuring low concentration SO2 based on gas difference absorption cross section characteristics

A technology of differential absorption and cross-sectional characteristics, applied in the direction of color/spectral characteristic measurement, etc., can solve the problems of long optical path, high detection concentration range, high measurement error, etc., and achieve the effect of simple principle

CN107271392AActive Publication Date: 2017-10-20CHONGQING UNIV
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Patent Information

Authority / Receiving Office
CN · China
Current Assignee / Owner
Publication Date
2017-10-20

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Abstract

The invention provides a method for measuring low concentration SO2 based on gas difference absorption cross section characteristics. The method comprises the following steps: firstly, primarily selecting a measuring spectrum scope of SO2 according to the SO2 ultraviolet absorption characteristics; secondly, calculating multiple difference absorption cross sections on the basis of multiple known SO2 concentrations according to a DOAS algorithm under the condition of unchanged temperature and pressure and gradually reducing the measuring spectrum scope according to the difference absorption cross section characteristics; thirdly, utilizing a statistic and standard deviation method to screen the spectrum sampling data point in a selected measuring spectrum scope and establishing an optimal sampling point data set, thereby acquiring an optimal difference absorption cross section data set; and lastly, utilizing the optimal difference absorption cross section data set and the DOAS algorithm to inverse the sulfur dioxide gas concentration. According to the method provided by the invention, the measurement principle is simple, the lower limit of the measurement is as low as 3ppm, the low-concentration gas can be accurately measured under a short optical path condition, the relative error can be controlled within + / -1.6% and the scale span error can be controlled within + / -1.2%.
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Description

technical field

[0001] The invention belongs to the technical field of ambient gas concentration detection and differential optics, and in particular relates to a method for measuring low-concentration SO2 based on gas differential absorption cross-section characteristics. 2 Methods. Background technique

[0002] Thermal power plants are one of the main sources of electricity in my country. With the vigorous construction of coal-fired power plants, coal combustion treatment has become the focus of research. my country is a country with coal as the main energy source, and its coal output ranks first in the world, while the reserves of high-sulfur coal account for 20% to 25% of the total coal reserves; in the national coal consumption, 84% of the total coal is consumed It is used for direct combustion, and a large amount of sulfur dioxide SO will be emitted during the combustion process. 2 , coal-fired sulfur dioxide emissions accounted for more than 85% of the total sulfur d...

Examples

Embodiment

[0043] A method for measuring low-concentration SO based on gas differential absorption cross-section characteristics 2 method, refer to figure 1 , including the following steps:

[0044] (1) Select the spectral measurement range; in order to improve the accuracy of data detection, the rough selection measurement spectral range is 200nm ~ 400nm, according to SO 2 According to the characteristics of the ultraviolet spectrum absorption band, the measurement spectral range is initially selected, and the preliminary measurement spectral range includes 180nm-235nm, 260nm-320nm and 340nm-400nm, and then the spectral range to be measured is continuously narrowed;

[0045] (2) Under the condition of constant temperature and pressure, multiple known SO 2 Differential absorption cross section at concentration, refer to figure 1 and image 3 , according to the differential absorption spectroscopy technique DOAS, the absorption spectrum I(λ) is obtained:

[0046] I(λ)=I o (λ)·exp[-L...