NDIR多组分气体分析的干扰修正方法研究

Research on the Method of Interference Correction for Nondispersive Infrared Multi-Component Gas Analysis

介绍了非分散红外(Non-Dispersive Infrared,NDIR)多组分气体分析的一种干扰修正方法。根据逐次积分气体吸收模型和方法,并考虑温度和气压对积分线强和线型的影响,选择洛伦兹展宽线型,得到了CO,CO2,NO和H2O在各个滤波通道的响应系数。利用响应系数建立了用于干扰修正的四元线性回归方程组,通过求解方程组,修正了气体间的吸收干扰,干扰修正后,各个滤波通道的吸光度只反映对应目标气体的浓度变化。将一定浓度比例的CO,CO2和NO混合气体通入样品池,将干扰修正后的吸光度直接用于浓度反演,CO2的反演误差为2.0%,CO为1.6%,NO为1.7%。理论和实验都证明提出的NDIR多组分气体分析的干扰修正方法是可行的。

A method of interference correction for nondispersive infrared multi-component gas analysis was described. According to the successive integral gas absorption models and methods, the influence of temperature and air pressure on the integral line strengths and linetype was considered, and based on Lorentz detuning linetypes, the absorption cross sections and response coefficients of H2 O, COs, CO, and NO on each filter channel were obtained. The four dimension linear regression equations for interference correction were established by response coefficients, the absorption cross interference was corrected by solving the multi-dimensional linear regression equations, and after interference correction, the pure absorbance signal on each filter channel was only controlled by the corresponding target gas concentration. When the sample cell was filled with gas mixture with a certain concentration proportion of CO, NO and CO2, the pure absorbance after interference correction was used for concentration inversion, the inversion concentration error for CO2 is 2.0%, the inversion concentration error for CO is 1.6%, and the inversion concentration error for NO is 1.7 %. Both the theory and experiment prove that the interference correction method proposed for NDIR multi-component gas analysis is feasible.