日照辐射对天然气超声波流量计流场修正系数的影响

Effects of Sunshine Radiation on Flow Correction Coefficient of Natural Gas Ultrasonic Flowmeter

2021年我国天然气消耗量为三千多亿立方,天然气测量的微小差异就会对经济效益产生巨大的影响,而目前市场上所使用的天然气流量计的可靠性却较差。天然气超声波流量计是应用最为广泛的非接触式天然气流量计量设备,其计量精度受到诸多因素的影响。基于ANSYS计算仿真平台,根据西安市地理位置及季节性特点,建立DN300管道的四声道超声波流量计数值模型,对天然气输运环境中的太阳辐射因素进行耦合研究。天然气超声波流量计的时差法计量原理是通过超声波顺逆流时间差来计量管道流体流量,其中流量修正系数是超声波流量计计量的关键参数,其定义是声道线平均速度与管道截面平均速度的比值。通过仿真结果分析得出以下结论:随着太阳辐射能变化,流场修正系数相对误差变化较小;考虑太阳辐射耦合进气速度时,对比有太阳辐射时的流场修正系数与不考虑辐射时的流场修正系数,冬季时的相对误差范围是0.005%~0.091%,夏季的相对误差范围是0.048%~0.27%。夏季的变化幅度较冬季明显,为提高超声波流量计计量精度,可以在夏季温度较高的中午对超声流量计仪表进行二次修正。

In 2021,China's natural gas consumption will be more than 300 billion cubic meters,and the small difference in natural gas measurement will produce huge benefits.However,the reliability of natural gas flowmeters currently used in the market is not considerable.Natural gas ultrasonic flowmeter is the most widely used non-contact flow measurement equipment,and its measurement accuracy is affected by many factors.Based on the ANSYS simulation platform,according to the geographical location and seasonal characteristics of Xi'an,this paper establishes a numerical model of four-channel ultrasonic flowmeter of DN300 pipeline,and studies the coupling of solar radiation factors in natural gas transportation environment.Through the analysis of simulation results,the following conclusions are drawn:with the change of solar radiation energy,the relative deviation of flow correction coefficient changes little;when considering the solar radiation coupling inlet velocity,the relative deviation range of the flow correction coefficient in winter is 0.005%~0.091%,and the relative deviation range in summer is 0.048%~0.27%.The change range in summer is more obvious than that in winter.In order to improve the measurement accuracy of ultrasonic flowmeter,the ultrasonic flowmeter instrument can be corrected twice at noon when the temperature is high in summer.