Application news: Natural gas pipeline transfer station uses ultrasonic flow measurement
Creating a metering system to monitor the flow of natural gas over national borders is a challenging task. Accuracy and reliability are very critical given the high product value and importance of an uninterrupted supply. Emerson Process Management has completed a long term project with a major upgrade of the pipeline metering stations between Russia’s Gazprom and Makpetrol in Macedonia. For this application, Emerson chose its Daniel SeniorSonic ultrasonic flowmeter technology.
The application had used orifice plate flow measurement, but Makpetrol wanted to introduce a more technologically advanced ultrasonic measurement method to monitor gas flow from a pipeline originating in Russia. The original measurement system consisted of three streams with orifice measurement technology. Makpetrol wanted to confirm the ability of the Daniel SeniorSonic meter as an accurate, reliable, cost-effective alternative for custody transfer measurement through side-by-side testing.
Emerson assumed full system responsibility, guaranteeing the operability, accuracy and quality of all components including conformance to local and national authority and code requirements.
The new metering system was commissioned throughout 2005. Since then, the difference between orifice and SeniorSonic base volume flows has been typically 0.5% or less. The advanced diagnostic checks and inter-comparisons available from the Daniel metering system have given operators a higher level of confidence in metering accuracy than previously possible. This confidence, along with the stable accurate performance of the meter, led to the Daniel SeniorSonic being approved for use for primary flow measurement by Makpetrol and Gazprom.
Milos Colovic, manager of metrology and head of the border station at Makpetrol said, "We are now certain that we measure gas flow accurately, as the different physical measuring principle of USM and orifice prevents a systematic error affecting the measurement result of the two gas meters. Pay/check configuration of the metering system allows us to verify that the meters are performing correctly. Based on the success of this installation which has been proven to be accurate, reliable, and user friendly, Makpetrol is planning to extend the use of this new technology based on the Daniel SeniorSonic meter to a third metering line.”
Emerson supplied the two new Daniel metering streams as pre-assembled flow metering tubes, each containing a 10 in., 600 lb SeniorSonic ultrasonic flow meter, Daniel Profiler flow conditioning plate, up and downstream pipe spools, and pressure and temperature transmitters. Each stream was designed to measure the full site flow rate of 180,000 Nm3/hr and each meter, along with its own up and downstream pipe spools, was flow calibrated in high pressure natural gas at the Advantica calibration facility in the U.K.
The streams are designed to comply with AGA-9 and ISO-5167 requirements. Flow measurement and analysis calculations, as well as PID flow control, are handled by Daniel FloBoss S600 flow computers. Gas quality monitoring is provided by Daniel Model 500 gas chromatographs with model 2350A controllers. The system was supplied with a Daniel DMS+ supervisory system to generate hourly, daily, weekly, and monthly totals for the meter readings.
Operators use Daniel CUI 4.10 software to access the advanced diagnostic capabilities of the flowmeters. The PC based software monitors advanced diagnostic parameters such as gain, signal-to-noise ratio, performance, VOS, profile geometry checks and timing checks. These diagnostics can be used to monitor not only the health of the USM components (transducers and electronics), but also used to check for changes in pipeline condition which could impact the accuracy of the measurement system.
—Edited by Peter Welander, process industries editor, PWelander@cfemedia.com , Control Engineering Weekly News