Low-concentration flue gas infra-red analyzer and detection method

Abstract

The invention belongs to the field of low- concentration flue gas infra-red analyzers and corresponding detection methods and provides a low-concentration flue gas infra-red analyzer which is high in both precision and reliability. The flue gas analyzer adopts the structure that a gaseous contaminant detecting unit 8 comprises an infrared light source 10 and a chopper 11 behind the infrared light source 10, as well as an absorption cell 12, a measuring gas chamber 13, a light filter 14 and a detection sensor 15 which are arranged along the light path behind the chopper 11; an absorption cell sample gas inlet 16 and an absorption cell sample gas outlet 17 are formed on the absorption cell 12; and the measuring gas chamber 13 is divided into a sample cell 20 and a reference cell 21 in the light path direction so as to measure the flue gas in a high-precision manner. According to the invention, a non-dispersion infrared monochromatic source is utilized to shine the sample gas, so as to realize quantitative and accurate analysis of the to-be-tested sample gas. The infra-red analyzer and the detection method, provided by the invention, are suitable for measuring a low-concentration NO flue gas, and can also be used for the detection of low-concentration CO, CO2 and other flue gases.

Description

technical field [0001] The invention belongs to the field of flue gas monitoring equipment, in particular to a low-concentration flue gas infrared analyzer and a detection method. Background technique [0002] Most of the existing low-concentration gas on-line detection methods use non-dispersive infrared absorption photometry. The basic principle is: after the sample gas is irradiated by a non-dispersive infrared monochromatic light source, the molecules in the sample will absorb light of certain wavelengths; the light that is not absorbed reaches the detector. After the detector detects the light intensity, it generates an AC voltage signal. After the signal is amplified and processed, it is analyzed by computer calculation to obtain the corresponding absorbance value of the gas. Since the absorbance is proportional to the concentration of the component in the sample, the sample gas to be tested can be quantitatively and accurately analyzed by using the size and spectrum ...

AI Technical Summary

Problems solved by technology

[0005] 1) For the sample cell or absorption cell, if a multi-reflection cell structure is used to increase the gas absorption optical path, the optical path design is relatively complicated, the mirror structure and process requirements are high, and interference fringes, optical aberrations, and even memory effects are likely to occur (for adsorption strong gas), resulting in a reduction in measurement accuracy;

[0006] 2) Infrared detector: If the front and rear gas chambers are arranged sequentially along the direction of the optical path, the infrared light passing through the measurement chamber will enter the light absorption chamber and then pass through another gas chamber, which will easily interfere with the measurement of the discharge detector. Accuracy, it is difficult to realize the measurement of low concentration gas stably

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