基于非分光红外法的高硫煤样全硫测定精度改善研究

Research on improving the accuracy of total sulfur determination in high sulfur coal samples based on NDIR

非分光红外法(NDIR)以其快速、非接触、试剂污染少、高选择性和低检出限的优势而被广泛用于煤样全硫的测定,但由于样品中硫的释放特性不同导致二氧化硫检测器输出的吸收峰谱差异较大,因而在动态测定场合中采用积分面积法进行全硫测定时,峰谱变化对硫检测器动态检测性能的要求更高,尤其在高浓度测定时易出现吸收饱和、输出信号呈现严重的非线性从而影响全硫测定结果的精度。结合非分光红外检测原理,从高浓度测定时NDIR的响应角度剖析高硫煤样NDIR全硫测定的特点,提出气路缓冲、吸光度线性化2个NDIR全硫测定精度改善方法,以改善检测器响应区间及有效控制检测器的测定误差。吸光度线性化算法用于标样测试的应用验证结果表明:通过气路缓冲装置的气流均匀化效应可降低待测二氧化硫的浓度峰,使得NDIR检测器工作在合理的浓度范围;吸光度标定算法可将检测器的非线性响应线性化,能显著改善高硫样全硫测定精度。

Non dispersive infrared(NDIR)method is widely used for the determination of total sulfur in coal samples due to its advantages of fast,non-contact,low reagent pollution,high selectivity,and low detection limit.However,the different release characteristics of sulfur in the samples,the absorption peak spectrum output by the sulfur dioxide detector varies greatly.In dynamic measurement situation,the integral area method is used for total sulfur measurement,and the peak spectrum changes have higher requirements for the dynamic detection performance of the sulfur detector,especially in high concentration measurements,absorption saturation and severe nonlinearity of the output signal are prone to occur,which affects the accuracy of total sulfur measurement results.Based on the principle of NDIR,the characteristics of NDIR total sulfur determination in high sulfur coal samples are analyzed from the perspective of NDIR response during high concentration measurement to improve the detector response range and effectively control the measurement error of the detector.Two methods for improving the accuracy of total sulfur determination are proposed:gas buffering and absorbance linearization.The application validation results of the absorbance linearization algorithm for standard sample testing indicate that the uniformity effect of the airflow through the gas buffer device can reduce the concentration peak of sulfur dioxide to be measured,that allowing the NDIR detector to work in a reasonable concentration range;The absorbance calibration algorithm can linearize the nonlinear response of the detector and significantly improve the accuracy of total sulfur determination in high sulfur samples.