基于红外技术的气体浓度检测方法研究

Gas Concentration Detection Method Based on Infrared Absorption Spectroscopy Technology

依据Lambert-Beer定律,推导出检测气体浓度的数学模型,得出了测量和参考探测器输出电压与气体浓度的函数表达式,表达式中的二个常数的数值取决于气室长度、气体吸收系数、探测器的电压探测率,经零点和满量程标准气样的标定,可确定这二个常数的数值,实现对仪器的标定.根据仪器零点随温度变化的关系,得到零点与温度函数表达式,用于零点温度补偿以及对零点温度补偿系数的计算;量程温度补偿方法是通过引入量程温度补偿因子,对测量和参考探测器输出电压与气体浓度的函数表达式进行修正,修正后的函数表达式用于量程温度补偿,也能对量程温度补偿因子中的补偿系数进行计算.矿用红外甲烷传感器采用本文的标定方法和温度补偿方法,在不同的环境温度下,对标准气样进行检测,其检测结果符合红外甲烷传感器标准所规定的基本误差.

According to the Lambert-Beer law,we derived mathematical model to measure the target gas concentration,and deduced the function which could be used for characterizing the relationship of the output voltage of the two detectors and the target gas concentration.The aim of calibration process is to determine the values of those two constants which depend on the length of the chamber,the gas absorption coefficient and the detector voltage detectivity in the above expression.Secondly,according to the feature of the measurements’ zero point changes with current temperature,the relationship between zero point and temperature was formulated.It can be used for zero temperature compensation and correlation of coefficient calculation.The scale temperature compensation method is the way to revise the function expression of the output voltage of the two detectors and the target gas concentration by introducing scale temperature compensation factor.The corrected function expression is used for compensating scale temperature and calculating the compensation coefficient of scale temperature compensation.Finally,the calibration and temperature compensation method above was applied to coal mine non-dispersive infrared methane transducer and the test results of standard gas samples testing under various ambient temperatures conform to the requirements in infrared methane sensor standard.