Rolls-Royce informed its thrusters are in place to power Shell’s Prelude.
The Prelude FLNG will be fitted with three Rolls-Royce electrically powered USL 455 azimuth thrusters at the Samsung Heavy Industries shipyard in Geoje, South Korea. They completed factory acceptance testing (FAT) during November, and left the factory in Rauma at the end of last year.
Prelude is 488m long, 74m wide and 44m deep from the keel to the main deck and will have a displacement of 600,000 tons. Once towed into position 200 km offshore the coast of Western Australia, in the Browse Basin, the production platform is not expected to see land again for over 20 years. It will remain operational around the clock and the thrusters will ensure it can keep its heading against the wind, current and waves to allow safe tanker berthing.
This 24/7 operation means any maintenance of the underwater mountable thrusters, which are each rated at 5.2MW will have to be carried out on board over the coming years, which demanded a unique approach to how the thrusters were installed.
Rolls-Royce teams in Norway, Finland, Korea and the UK were involved in tailoring the solution specifically for Prelude. To facilitate thruster overhaul or replacement while at sea, each electrically-powered thruster is located at the base of a purpose designed trunk which links to the higher workshop area with its dedicated cranage. The maintenance space has all the functions and tooling found in the Rauma production facility.
Condition monitoring
Thruster condition monitoring system (CMS) is also part of the Rolls-Royce supply, type approved by ABS, Lloyds Register and DNV GL. CMS data can be used to determine the actual condition of the thrusters through life, without the need for internal and visual inspections. Maintenance and overhaul intervals can be extended to match the operating profile of the vessel. Rolls Royce adds that the CMS is wirelessly linked to an onshore Rolls-Royce operations center where the data is analyzed to produce the trending and operational information. The data analyzed represents a carefully considered balance of thruster information for maximum effectiveness in highlighting any potential operating anomalies, long before they can be seen or heard.
Once operational Prelude is expected to produce 3.6 MMT/a of LNG, enough to meet Hong Kong’s annual natural gas demand – as well as 0.4 MMt/a of LPG and 1.3 MMt/a of gas condensate.
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Image: Rolls-Royce, Shell