Research On Improvement Technology Of Measurement Characteristics Of Atmospheric Gas Flow Standard Device

With the construction of urban natural gas pipeline,the market stock of atmospheric natural gas flow meters used in public facilities,factories,hotels and restaurants at the end of pipe network in Daqing area is about 2000,and the number is increasing.The atmospheric natural gas flow meters used in industrial production and trade transfer around Daqing and all over the country are also increasing.According to the requirements of the metrology law,the measuring instruments used for natural gas trade handover should be regularly traced to the national metrology verification system.The National Petroleum and natural gas large flow metering station is responsible for domestic atmospheric gas flow metering.Its original metering standard has a long service life,and various devices are aging seriously,which affects the accuracy of flow metering.It is urgent to carry out equipment transformation.At present,its working level standard has narrow verification flow range,low verification flow meter level,and high measurement uncertainty,It has been unable to adapt to the current verification task and needs to be updated.In order to meet the needs of atmospheric natural gas flowmeter verification(calibration)in Daqing region and the whole country,the key technologies of atmospheric natural gas traceability system were studied.1.Through temperature and pressure correction technology,displacement redundancy measurement technology and flow dynamic adjustment technology,the uncertainty of bell type gas flow standard device is increased from Ur=0.1%(k=2)to Ur=0.08%(k=2),reaching the domestic advanced level.2.Through working principle research and process optimization,two sets of critical flow Venturi nozzle standard devices are newly built,with uncertainty Ur=0.33%(k=2)and measurement range(1?6000)m~3/h,which can meet the verification requirements of various atmospheric natural gas flowmeters with diameter of DN300 and below and accuracy level of 1.0.3.Participated in the primary standard comparison test organized by China Institute of Metrology and carried out by Chongqing Institute of metrology,the flow deviation was less than±0.103%,which verified the accuracy and reliability of the standard device.The research results of this project can provide technical services or products for the design and manufacture of atmospheric natural gas measurement standards of Daqing Oilfield and even nationwide metrological verification institutions,and provide efficient and high-quality value traceability services for atmospheric natural gas trade flowmeters in Northeast China and even the whole country.In the past two years,1884 new types of natural gas flow meters have been added for verification and calibration,with a verification income of 2.7264 million yuan.It has also provided high-quality services for enterprises in Hubei,Shanxi,Beijing and other parts of the country,creating huge economic and social benefits.