A Brief Review of Natural Gas Metering Status at Home and Abroad
As a kind of high-quality energy and chemical raw materials, the measurement of natural gas is getting more and more attention. Developed countries, such as Europe and the United States, with higher industrialization levels started their research on natural gas measurement technology earlier and invested more funds and technology, especially the measurement of trade natural gas. From the flowmeter selection, the main use of turbines in Europe, the waist wheel flow meter, such as the Netherlands turbine, waist wheel flow meter used about 80% in Canada, the use of turbine flow meters accounted for about 90%, while the United States to use Orifice-based, accounting for about 80%. As a whole, in the use of flowmeters, the climax of the orifice plate was formed in the 1970s, and the climax of the turbine flow meters was formed in the 1980s. In the mid- and late 1990s, the upsurge of ultrasonic flowmeters was set off.
As for traffic standards, traffic workers in various countries spend a lot of time and hard work. Based on the analysis of a large amount of experimental and applied data, representative standards such as AGANo .3), AGANo.7, AGANo.8 for natural gas and other hydrocarbon gases, AGANo.9 for gas ultrasonic flowmeters, AGANo.9 for gas turbines, (ISO5167), Gas Turbine Meters (ISO9951), Gas Ultrasonic Flow Meters (ISO / TR12765), and Natural Gas Compressibility Computation Standards (ISO / DIS12213), etc. These standards are applicable to the measurement of natural gas flow Has a positive guiding significance.
In the meantime, people in foreign countries gradually shift their focus from the dry-sticking method to the pattern of confirming the actual flow-one focusing on traceability and quantity transfer. Many flow verification laboratories such as CEESI ), Southwestern Research Institute (SWRI), NMI, TCC, Pigsar, NEL, NRLM.
In recent years, the European Commission for the Metrology of Oils of the International Legal Metrology Organization (OMIL) has drafted International Proposal PREN1776, "Basic Requirements for Natural Gas Metering Systems", setting out in more detail the composition of natural gas metering systems and the specific requirements for auxiliary equipment. Natural gas measurement system design principles and design guidelines, measurement system online verification, installation and operation and maintenance were provided.
China's natural gas measurement started later, gas reservoirs are mainly located in Sichuan, Changqing, Xinjiang, the use of instrumentation mainly used orifice plate selection, the proportion of about 88%, the use of geometric verification. Since the 1970s, our country has made corresponding efforts in the design, selection, use, installation, maintenance, management and temperament analysis of natural gas meters with reference to foreign series of standards and in light of their own actual conditions. Some important conclusions have been drawn At the same time, it has found some mature experiences on the influence of on-site resistance and complex working conditions, and formed the standard of "standard orifice measurement method of natural gas flow" (SY / T6143-1996) in terms of standard, equivalent ISO5167 to form GB2624 However, on the overall level, there is still a significant gap with foreign countries.
In recent years, China's gas measurement technology new progress
Due to its inherent defects such as constant wear and corrosion of the orifice plate during use, the combination of on-site resistance components is far more than metrological techniques for orifice orifice throttling devices and their secondary instrument dual bellows differential pressure gauges, which are widely used in our country. Standard conditions of the seven kinds of situations; on-site vortex flow, pulsatile flow influencing factors complex; for large fluctuations in gas, the high frequency of changes in the poor adaptability; lead tube easy to cause signal lag [1], can not guarantee its measurement accuracy, which To traffic workers brought new research topics. In recent years, China's natural gas metering technology has made the following new progress.
l, orifice throttling device secondary instrument intelligent
Since 1998, some secondary gas meters have been retrofitted with some natural gas metering devices. The smart metering transmitters, temperature transmitters and flow computers have been gradually adopted on site to replace the dual bellows differential pressure gauges, thus realizing the automation of metering . The transmitter of the system has the advantages of high accuracy, good stability, online fault diagnosis, configuration and verification using its communication function. The natural gas flow measurement gradually moves toward on-line, intelligent and real-time measurement.
2, to adapt to small and medium-sized flow of new intelligent flowmeter applications
To solve part of the scene in the case of small and medium flow and low pressure fluctuations in the larger, less accurate metering orifice problem, the domestic launch of intelligent swirl into the vortex flowmeter, intelligent turbine flowmeter, such flowmeter can collect pressure online , Temperature, working flow, calibration flow, real-time correction of compression factor and automatic temperature and pressure compensation. After actual flow calibration and in the field a wide range of applications (such as Sichuan, Xinjiang, Dagang, Daqing, etc.), the effect is better. Recently appeared this type of double probe intelligent flowmeter, anti-interference ability to further enhance.
3, high pressure flow measurement technology research
With the rapid development of foreign gas ultrasonic flow meters, our country keeps track of advanced foreign measurement techniques in a timely manner. Since 1999, the project has been led by Chengdu National Natural Gas Flow Substation (hereinafter referred to as the measurement substation) of the National Crude Oil Large Flow Metering Station, American Daniel, the Netherlands Instromet, the United States Contronlotron gas ultrasonic flowmeter produced a real-time test to study the ideal installation conditions, non-ideal installation conditions, different angles of rotation installation conditions, with pressure to replace ultrasonic transducers, different pressure conditions, Channel failure state performance and field applications. Obtained gas ultrasonic flowmeter after the school still need real-time verification and periodic inspection and other important conclusions [2]. After the gas flow test, Beijing, Daqing, Xinjiang, Sichuan, Tianjin, Hebei and other countries have gradually introduced about 40 gas ultrasonic flow meters. Diameter DN150mm-DN400mm between the uncertainty of 0.5% -1.0%.
4, real flow test technology development
In the past the standard orifice has been used "geometric test method", the flow rate calibration device usually use air as a medium, negative pressure test. Huayang Metering Substation was completed in 1996 with mt standard equipment of the original level with a total uncertainty of 0.1% and the introduction of a secondary standard flow of critical flow sonic nozzles from CEESI of the United States with a total uncertainty of 0.25% with natural gas flow Flow test conditions. In the recent 4 years, the technology of real flow verification has matured. A full set of verification methods, procedures and management systems have been established for solid flow of natural gas. The techniques and standards of foreign countries such as the United States, the Netherlands, the United Kingdom and Germany are gradually approaching. In order to better simulate the scene conditions, reduce the series of difficulties caused by loading and transportation, and control and reasonably reduce the on-site measurement error, the real flow verification in our country gradually went from the interior to the scene. For example, the mobile sonic nozzle calibration vehicle (pressure 1.6MPa, diameter DN200mm, flow rate 90000m3 / h) of the National Crude Large Flow Metering Station (Daqing), the newly purchased mobile gas ultrasonic flow calibration vehicle (pressure 6.4MPa , Diameter DN600mm, working conditions flow 80-800
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