流量计直管段适用长度的探讨  

Discussion on Suitable Length for Straight Pipe of Flowmeter

作　　者：谢林[1] 殷家云 纪波峰 纪纲 

机构地区：[1]上海市电力公司电力科学研究院,上海200437 [2]中石化上海工程有限公司,上海200120 [3]上海同欣自动化仪表有限公司,上海200070

出　　处：《石油化工自动化》2014年第5期58-62,共5页Automation in Petro-chemical Industry

摘　　要：现有流量计中,除了容积式流量计、科里奥利质量流量计之外,其他流量计对前后直管段有特定的要求,且不同类型的流量计所要求的直管段长度也差异悬殊。直管段长度不够时引起流量测量不确定度增大的原因:流体流过弯管或阀门时,速度分布产生畸变,导致实际流量系数与出厂标定时的流量系数不一致。常用对策包括:管线绕道法,简单易行;降低精确度指标,在普通监测和过程控制中亦经常采用;将流量传感器在管道上的安装方位选择在最有利的位置;加装流动调整器和选用直管段长度要求低的流量计。同时,对以上几种对策进行了比较与分析。All flowmeters have specific requirements for straight pipe before and after valve excluding volumetric flowmeter and Coriolis mass flowmeter among current used ones. There is big gap for required straight pipe length among different type flowmeter. Shorter straight pipe results in more uncertainty of flow measurement. Velocity distribution distorts and causes actual flow coefficient different from calibrated data while fluid passes through elbow or valve. Common countermeasures used are as following： simple and easy detour, reducing precision index regularly used in normal monitoring and process control, installing flowmeter at a good position of pipeline, installing a flow regulator or selection and using flowmeter with low requirements for straight pipe length. Above mentioned countermeasures are compared and evaluated.

关 键 词：流量计 直管段 让步法 绕道法 流动调整器 影响评估法 

分 类 号：TH814[机械工程—仪器科学与技术]