Low-concentration and multi-component gas detection method based on integration of multiple spectrum technologies

Abstract

The invention discloses a low-concentration, multi-component and high-sensitivity gas detection method based on integration of multiple spectrum technologies. Advantages of an ultraviolet differential optical absorption spectroscopy (DOAS) technology and an infrared tunable diode laser absorption spectroscopy (IR-TDLAS) technology are integrated, so that information integration and characteristic signal extraction of two kinds of spectrum are realized. The method disclosed by the invention is used for measuring the NH3 concentration in smoke by utilizing a TDLAS method and simultaneously measuring the concentrations of SO2 and NO2 in smoke by utilizing an ultraviolet DOAS method; interference of three components in the NO absorbancy is removed according to the obtained concentrations and an interference spectrum of three kinds of gas to the NO absorbancy, so that the NO concentration without cross interference is solved; and thus, the measurement precision and the detection lower limit are greatly increased.

Description

technical field [0001] The invention relates to a low-concentration, multi-component and high-sensitivity gas detection technology based on the fusion of multiple spectral technologies, which belongs to the technical field of spectral measurement. Background technique [0002] Currently used in industrial pollution source flue gas emissions and SO in the production process 2 , NO, NO 2 Concentration online monitoring technology can be mainly divided into non-dispersive infrared absorption method, electrochemical method and differential absorption spectroscopy (DOAS, Differential Optical Absorption Spectroscopy) according to its principle. [0003] A large number of engineering applications and repeated laboratory tests have shown that most of the infrared instruments currently have low concentrations of SO 2 , NO measurement accuracy is low, linear deviation is large, and the detection limit of the instrument is high, especially at low concentrations (less than 50mg / m 3 )...

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Problems solved by technology

[0003] A large number of engineering applications and repeated laboratory tests have shown that most of the infrared instruments currently have low concentrations of SO 2 , NO measurement accuracy is low, linear deviation is large, and the detection limit of the instrument is high, especially at low concentrations (less than 50mg / m 3 ), the interference of moisture on the measurement is obvious, and the measurement results have large deviations, which makes it more and more difficult to meet the increasingly stringent flue gas emission standards; electrochemical analysis methods have serious cross-interference and are susceptible to moisture, H 2 S, NO, NO 2 The effect is mainly applicable to the short-term SO 2 Concentration detection; UV differential absorption spectrometry can detect SO 2 , NO 2 The two components are detected with low concentration and high sensitivity, but cannot remove NH under denitrification conditions 3 Cross-interference to low concentrations of NO

[0004] With the continuous improvement of the country's smoke emission standards and the number of target monitoring gases (NH 3 ) increases, existing monitoring instruments and equipment all have SO 2 , NO low concentration measurement accuracy is poor, the measurement component is "single" and other problems

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