关键词: 紫外差分吸收光谱, 光谱仪, 波长校准, 吸收光谱

Abstract:

Ultraviolet differential absorption spectroscopy technology has been widely used in the monitoring of industrial flue gas emissions. The spectrometer, a core component of the UV flue gas analyzer, is susceptible to wavelength drift caused by temperature changes, which in turn affects the accuracy of pollutants monitoring results. In this paper, a soft wavelength calibration method for spectrometers is proposed. A standard SO₂ absorption spectrum peak wavelength database is established through experiments. When the wavelength drift exceeds 0.02nm, the corresponding function between the spectrometer pixel and wavelength will be re-fitted using the pixel of the SO₂ absorption peak in conjunction with the database. This method enables real-time calibration of the spectrometer wavelength. Experiments are conducted to validate the proposed calibration method. Results showed that with a 10℃ environmental temperature range, this method can reduce the measurement error of 993mg/m³ NO standard gas from 115.2mg/m³ to 21.4mg/m³, with an absolute error reduction of 93.8mg/m³. The best wavelength calibration effect is achieved when the measured SO₂ concentration is 1430mg/m³. For low-concentration measurement sites, the signal-to-noise ratio of the spectral signal can be amplified by increasing the number of spectral averages, thereby improving the effectiveness of the online wavelength calibration method.

Key words: ultraviolet differential absorption spectroscopy, spectrometer, wavelength calibration, absorption spectrum