National Grid selects Sensa for pipeline temperature monitoring at UK's first LNG plant for 20 years

Citation

(2006), "National Grid selects Sensa for pipeline temperature monitoring at UK's first LNG plant for 20 years", Sensor Review, Vol. 26 No. 2. https://doi.org/10.1108/sr.2006.08726bab.003

National Grid selects Sensa for pipeline temperature monitoring at UK's first LNG plant for 20 years

National Grid selects Sensa for pipeline temperature monitoring at UK's first LNG plant for 20 years

Keywords: Fibre optic sensors

Distributed temperature sensing system installed in new 4km pipeline at Isle of Grain terminal.

Sensa, a leading provider of fibre optic temperature sensing and monitoring solutions for critical assets around the world, has announced that its fibre optic distributed temperature sensing (DTS) system has been chosen by National Grid plc for continuous temperature monitoring of a new 4km pipeline at the first UK LNG (liquid natural gas) importation terminal for 20 years at the Isle of Grain, Kent.

A bespoke DTS system designed by Sensa has been installed at the terminal, providing 82 sensing elements that are attached to the top and bottom surfaces of the pipe. The pipeline forms part of the first phase of the development of the LNG terminal at the Isle of Grain, which was opened earlier this year as part of National Grid's development project and £130m of initial investment.

In addition to an ongoing temperature monitoring process, the system has already successfully monitored the preliminary process of cooling along the pipeline, which must be done prior to the first transportation of the LNG to reduce stress and damage on the pipes. In order to maintain the pipes at a crucial temperature of 21618C, when natural gas becomes liquid, small amounts of LNG are flushed through the pipes. The whole cooling process was carried out over four days, ending with a successful first LNG shipment of 138,000m³ transported along the pipeline from ship to storage tanks on the shore.

“With Sensa's DTS system we are able to pinpoint a temperature anomaly to the nearest metre in the pipeline, so that if there is a detected leak we can locate and repair any problems quickly and without causing further damage,” says Ian Belmore, Site Manager at National Grid's Grain LNG facility. “Work has now commenced on the second phase of this project, which will triple the size of the facility and volume of LNG processed.”

Sensa's DTS solution utilises the latest fibre optic technology to provide real-time data regarding temperature measurements over many thousands of individual points, across the entire surface of the tanks or pipelines for distances up to 30km using a single fibre. This enables the ongoing analysis of actual measurements.

Using the principles of optical time domain reflectometry, pulses of light are fired through the fibre optic cable. These pulses lose energy through scattering during transit as they pass down the fibre through several mechanisms, including density and composition fluctuations (Rayleigh scattering) as well as Raman and Brillouin scattering, due to molecular and bulk vibrations respectively. A fraction of the scattered signal is retained within the fibre, where a portion of this is directed back along the fibre towards the laser source creating a backscatter.

The combination of variations in backscattered light intensity and time domain reflectometry are measured to create accurate temperature against distance profiles. Sensa's DTS technology is able to monitor fibre optic cable to accurately and speedily notify the position and intensity of any temperature event along the fibre optic cable. A potential LNG leak would be highlighted as a cold spot on a temperature trace, as the freezing LNG seeps from the lagged inner pipeline into an outer pipe.

For more details please visit the web site: www.sensa.org