Evaluation project sees Raman analysis proves its worth in LNG custody transfer

Endress+Hauser’s Raman spectroscopy-based analyser systems have been found to be a reliable and low-maintenance alternative to traditional gas chromatography (GC)/vaporizer systems for liquefied natural gas (LNG) composition and energy content measurement during custody transfer transactions, according to a years-long study by the European Gas Research Group (GERG). The study, which involved 33 GERG members from 15 countries across Europe, compared different methods for LNG composition measurement.

“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.”

The demand for LNG as a means to efficiently transport large quantities of natural gas around the world is increasing as the world strives to reduce greenhouse gas emissions and cope with energy supply chain disruptions. The transfer of custody during LNG transport by land and sea is one of the most critical steps in the LNG process chain.

Fast and reliable LNG composition measurement is essential at each key point of contractual exchange. Even tiny differences in calorific value can alter the value of an LNG load by hundreds of thousands of euros.

The GERG evaluation project aimed 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 multi-year 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 an Endress+Hauser Raman system comprised of a 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 the significantly lower operating expense and technical expertise than traditional GC/vaporizer systems.