背景气体对SO_2监测仪测量不确定度的影响

Effects of Background Gas on Measurement Uncertainty of SO_2 Monitor

为了研究背景气体的种类及浓度对紫外荧光法SO2自动监测仪不确定度的影响,在重复性条件下分别测量了H2S,NO,CO,CO24种常见背景气体浓度在仪器量程达到20%,40%,80%时监测仪的示值误差。采用直接评定法对背景气体引起的不确定度分量、标准不确定度进行了评定。实验结果表明,H2S和NO两种气体引入的不确定度是背景气体中影响测量不确定度的主要因素,且在其他测量条件不变的条件下,SO2自动监测仪的测量不确定度随着背景气体浓度的增加而增大,并对该实验结果产生的原因进行了分析。在利用紫外荧光法在线监测SO2气体浓度时,应根据背景气体的实际情况对SO2自动监测仪的示值浓度进行实时补偿计算,能够有效提高SO2自动监测仪在线测量的测量精度。

To study the effects of background gas type and concentration on the measurement uncertainty of UV fluorescence SO2 automatically monitor, in the repeatability conditions, the indication errors of four common background gases, H2S, NO, CO and CO2, were measured, and the concentration was in the full range of equipment 20%,40%,80%. The uncertainty components and standard uncertainty caused by background gas were evaluated with the direct evaluation method in detail. The experimental results indicate that the major factors affecting measurement uncertainty of background gas are NO and H2S. At the same condition, the measurement uncertainty of SO2 increases with the concentration of the background gas and the causes of the experimental results were analyzed. A compensation calculation of the indication concentration on SO2 monitor with respect to background gas effect is indispensable for improving online measurement precision of SO2 concentration,when the SO2 concentration is measured on line by the ultraviolet fluorescence method.