天然气流量计量系统的检定和校准

VERIFICATION AND CALIBRATION OF NATURAL GAS FLOW MEASURING SYSTEM

当前我国管道天然气计量系以体积表示 ,就其计量器具而言 ,差压式流量计、容积式流量计和速变式流量计都有 ,但大流量计量大多仍采用标准孔板差压式流量计 ,其流量计量标准执行我国SY/T6 143 - 1996《天然气流量的标准孔板计量方法》。文章介绍目前常用的三种流量计的优缺点比较 ;天然气标准孔板差压式流量计算机自动计量系统的检定 ,其中包括 :标准孔板节流装置 ,静压、差压变送器、温度传感器、数据采集系统等组件的检定 ;以及计量器具的正确使用和维护。最后 ,文章指出目前流量计量的发展主要是二次仪表的发展 ,籍助应用计算机大大提高流量计的测量范围和准确度 ,但对用户来说 ,应选择性 /价比合适的仪表 ,并要考虑所选用仪表要便于检定、维护 ,同时 ,计量检定部门则应跟上发展 ,为广大用户提供技术支持。

The measuring result of pipeline gas flow is expressed as volumetric units in China at present and the measuring appliances include differential pressure flowmeters, volumetric flowmeters and variable speed flowmeters. However the standard orifice differential pressure flowmeters are still adopted for measuring a large gas flow rate and the SY/T6143 - 1996 Standard Orifice Measuring Method of Natural Gas Flow issued by China has been taken as the measuring standard. The contrast of merits and demerits among the three flowmeters; the, verification of the computer automatic measuring system of the standard orifice differential pressure gas flow rate, including the examination of standard orifice restricting device, static pressure-differential pressure transmitter, temperature sensor and data acquisition system, etc. ; and the correct application and maintenance of the measuring appliances are introduced in the paper. Finally the authors point out that the development of flow measurement at present is that of secondary instruments; the measuring scope and accuracy of the flowmeters are greatly raised with the aid of computers; and for the users, the instruments with suitable property-price ratio should be chosen and it is necessary to consider the instruments chosen being easy to be verified and maintained as well as the measurement examining departments should keep pace with the technological development to provide technical support for the vast numbers of users.