高精度主给水超声波流量计的不确定度分析方法

Method for Analyzing Uncertainty of High Precision Ultrasonic Flowmeter for Main Feedwater

针对华龙一号等国内核电机组为实现小幅功率提升而提出的主给水流量高精度测量需求,通过对比分析高精度主给水超声波流量计的工作原理,确定了校准系数与介质密度等超声波流量计测量不确定度分量来源。此外,从仿真和实测相结合的角度出发,结合超声流量计的结构、测量原理和高温高压复杂工况等条件,对影响质量流量的声道几何因子和管道截面积两个分量,给出了针对不同情况下的不确定度评估方法。分析了实际安装环境对流量测量的影响,提出了如何评定流场流速所引入的不确定度,最终结合几种不确定度评价方法建立了高精度主给水超声波流量计的计量溯源方法。

The methodology of high-precision measurement of main feedwater flow is proposed based on Hualong No.1 and other nuclear power plants(NPP) to achieve measurement uncertainty recapture power uprates(MUR).The components of uncertainty measured by ultrasonic flowmeter such as calibration coefficient and medium density are quantified.Under the conditions with defining the structure and measurement principle of ultrasonic flowmeter and the complex operating conditions of high pressure and high temperature(HPHT),the uncertainty evaluation methodology of channel geometric factor and pipe cross-sectional area has been given respectively.By analyzing the influence of the operating conditions on the flow measurement,the uncertainty introduced by the flow field velocity has been evaluated.The analysis results indicate that the metrological traceability method which based on the combination of several uncertainty evaluation methods is feasible.