Coriolis Meters and Cryogenic Testing Experience
Micro Motion Coriolis flow meters have been used in many applications from transmission and distribution to dispensing of high pressure natural gas across all industries and around the world. One lesser known application for the meters includes Liquefied Natural Gas (LNG): natural gas in the cryogenic state.
Micro Motion Coriolis meters have been installed to handle LNG across the US, Canada, Australia, China, and France. Many more units have been tasked with measuring the purity of cryogenic liquids such as nitrogen and argon flow in cryogenic bulk transfer and monitoring installations. New tanker off-loading terminals have applied Micro Motion units to LNG metering and high capacity flow. After more than a year of successful operation, these installations have proven a practical demonstration of the capabilities of Micro Motion technology.
Early research into the original equipment installed for such purposes revealed the unique properties of stainless steel at cryogenic temperatures. This information has long been incorporated as a patented feature in the standard flow electronics of Micro Motion Coriolis meters, which ensures accurate flow performance at low operating temperatures.
The National Institute of Standards and Technology (NIST) conducted further testing at a facility that included a cryogenic flow measurement test stand. These tests of a Micro Motion Coriolis meter demonstrated a maximum spread of ±0.6% in flow measurement performance.
Additionally, the NIST tests confirmed that Emerson’s Micro Motion standard factory calibration routines, which are made using room temperature fluids, are totally adequate and transferable to on-site meter operation with cryogenic fluid. This gives operators ultimate flexibility while maintaining measurement confidence.
While LNG temperatures could cause icing on uninsulated piping, the flow measurement tubes in a Micro Motion Coriolis meter are enclosed with an outer metal casing, similar to a vacuum jacket. Between the vibrating flow tubes and the exterior casing, the interior space is filled with a dry, inert gas which eliminates any possibility of icing on the vibrating tubes themselves. Even if icing should form on the outer case or pipe flange connections, it would have no effect on meter measurement performance.
The Meter of Choice
Micro Motion Coriolis meters have become a well-established meter of choice for custody transfer in oil and gas pipelines and terminals, lauded for their high standards in meeting the relevant API and regulatory requirements and long-term meter factor stability. Now, in new shipping terminals around the world, the same meters are gaining recognition as the first choice for custody transfer metering of cryogenic liquids such as LNG. Manufactured to the highest standards of quality by Emerson to simplify the handling and metering of bulk LNG transfers, Micro Motion meters continue to expand their reach and multiply their application potential.