TDLAS测量CO<sub>2</sub>的温度影响修正方法研究

doi:10.3964/j.issn.1000-0593(2018)07-2048-06

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Abstract Tunable diode laser absorption spectroscopy (TDLAS) is often used to detect CO₂ concentrations in many fields. But because of the variation of ambient temperature, the measured the line strength and line-shape are affected and may lead to the monitoring errors. Therefore, in order to overcome the influence of temperature change on the concentration measurement, we used the DFB laser with the center wavelength of 1 580 nm and the direct absorption method was used to measure the high concentration of carbon dioxide gas in the flue of the power plant under the condition of room temperature (298 K) and variable temperature (298~338 K，interval 10 K). The results showed that the maximum relative error of the concentration measurement was -5.26%, the minimum relative error was 1.25% and the relative error mean square was 3.39%, which indicated that TDLAS measurement system had good measurement precision and stability at room temperature. But the concentration measurement in the temperature measurement error, the maximum of relative error was more than 25%. Then, the influence of temperature change on the measurement of the concentration was solved to meet the needs of industrial measurement and on the basis of temperature change measurement, the least squares method was used to fit the correction relation between the concentration of the measurement system and the gas absorption at different temperatures. After the correction, the relative error of the CO₂ concentration measurement was reduced to below 5%, and the relative error mean square value fell below 3.5%.The correction results showed that the proposed method can effectively suppress the influence of temperature change on the concentration measurement and improve the measurement accuracy and stability of the system in the variable temperature environment, which provides theoretical support and technical support for the TDLAS system field application.

Key words：Tunable Diode Laser Absorption Spectroscopy (TDLAS); CO₂ concentration; Temperature correction; Least square method; Direct absorption method

Received: 2017-08-07 Accepted: 2017-12-28

ZTFLH:

O433.1

Corresponding Authors: YAO Shun-chun E-mail: epscyao@scut.edu.cn

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https://www.gpxygpfx.com/EN/10.3964/j.issn.1000-0593(2018)07-2048-06 OR https://www.gpxygpfx.com/EN/Y2018/V38/I07/2048