Raman analysis proves its worth in LNG custody transfer

As the world strives to reduce greenhouse gas emissions and cope with energy supply chain disruptions, demand for LNG as a means to efficiently transport large quantities of natural gas around the world is skyrocketing. One of the most critical steps in the LNG process chain is the transfer of custody during LNG transport by land and sea. At each key point of contractual exchange, fast and reliable LNG composition measurement is essential. Even tiny differences in calorific value can alter the value of an LNG load by hundreds of thousands of dollars.

Recently, the European Gas Energy Group (GERG) embarked on a project to validate the measurement capabilities of Raman technology to deliver reliable, accurate and precise composition measurements for energy calculation in LNG custody transfer applications. During the multiyear study, thorough testing was performed at a baseload LNG transfer facility at Fluxys LNG in Zeebrugge, Belgium. To ensure the data met LNG metrology standards, reference LNG samples were provided by EffecTech, a leading provider of inspection, calibration and testing. Measurements of LNG were taken directly in the liquid phase by a Raman analyser system comprising an Endress+Hauser Raman Rxn-41 cryogenic probe fibre-optically coupled to a Raman analyser optimised for LNG.

The published GERG report, ‘Raman method for determination and measurement of LNG composition’, concluded that Endress+Hauser Raman analyser systems offer equivalent LNG measurement uncertainty with significantly lower operating expense and technical expertise than traditional GC/vaporiser systems. Not only did the Raman system reduce the complexity of the LNG monitoring system and have faster startup stabilisation times, it also proved to have better repeatability, responded more quickly to process changes and required no maintenance during the entire evaluation period (experiencing >99% uptime). These results demonstrate the value of using Raman measurement technology for field installations at LNG baseload, satellite and peak shaving sites, as well as for LNG truck loading and bunkering ships.

“Raman spectroscopy is swiftly gaining traction around the world as a robust, efficient and economical analysis technique for LNG composition measurement,” said John Schnake, Managing Director and Corporate Director Process Analyzers at the Endress+Hauser Group. “Our Raman instrumentation allows companies to have confidence in the accuracy and precision of their LNG measurements during critical custody transfer transactions with a significantly reduced maintenance burden.

“We are pleased the results presented in the GERG study reinforce the value of our Raman analysis portfolio for LNG custody transfer applications. By providing fast and reliable liquid-phase measurement at such vital points in the LNG process chain, our Raman systems play an important role in the evolving global energy transition.”

Image: Measurement of LNG composition with an Endress+Hauser Raman probe in a bunker ship.