Low-concentration gas measurement method based on direct absorption spectroscopy

By eliminating cross-interference and baseline effects through direct absorption spectroscopy, low-concentration and high-sensitivity detection of NO2 components is achieved, solving the accuracy and stability problems of NO2 measurement in existing technologies, and making it suitable for monitoring industrial pollutant emissions.

WO2026113187A1PCT designated stage Publication Date: 2026-06-04NANJING GUODIAN ENVIRONMENTAL PROTECTION TECH CO LTD
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Patent Information

Authority / Receiving Office
WO · WO
Patent Type
Applications
Current Assignee / Owner
NANJING GUODIAN ENVIRONMENTAL PROTECTION TECH CO LTD
Filing Date
2025-03-14
Publication Date
2026-06-04

AI Technical Summary

Technical Problem

Existing technologies cannot effectively achieve low-concentration, high-sensitivity detection of NO2 components, and suffer from cross-interference and measurement errors, making it difficult to meet the accuracy and stability requirements for industrial pollutant emission monitoring.

Method used

By employing direct absorption spectroscopy, the cross-absorption spectra of SO2 and NO2 in their absorption bands and the zero absorption baseline are calculated to eliminate light intensity reduction and interference, thereby extracting pure NO2 absorption spectral data. The NO2 concentration is then calculated using the absorbance in the 260–315 nm band, eliminating cross-interference and baseline effects.

Benefits of technology

It improves the accuracy and signal-to-noise ratio of NO2 concentration measurement, lowers the detection limit, achieves long-term stable measurement of low-concentration NO2, eliminates data deviations caused by human modification of system components, and ensures the reliability of pollutant emission monitoring.

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Abstract

Disclosed in the present invention is a low-concentration gas measurement method based on direct absorption spectroscopy. In the method, real-time measured spectral data of a gas under test and a database of absorption cross sections of said gas measured in a laboratory are used, the concentration of SO2 is calculated by means of ultraviolet differential absorption spectroscopy, an interference spectrum of SO2 on NO2 is calculated, the influence of SO2 on the absorbance of NO2 is eliminated, the absorbance at a zero absorption position is calculated, the influence of spectral attenuation on measurement is eliminated, and the concentration of NO2 after elimination of cross interference is accurately calculated, thereby greatly improving the measurement accuracy and lowering the measurement limit.
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