Floating LNG Plants Can be Built

Bouygues Offshore announced the successful completion of the AZURE R&D project for the development of floating Liquefied Natural Gas (LNG) facilities concepts. A consortium of 9 European companies completed the project. The objective was to address all technical issues in order to demonstrate that a fully floating LNG chain, from gas well to gas distribution network, is a safe and viable industrial proposal. The 18-month work program called for designing floating liquefaction plants, floating LNG terminals and offshore LNG transfer systems. It included thorough testing of all the key components of the chain.

For the liquefaction barge, two different scenarios were developed - in South East Asia, a stand-alone gas field involving a 3 MMTPA capacity, based on a dual mixed refrigerant process cycle and in West Africa, a single processing train, involving a 1 MMTPA capacity with a nitrogen expander cycle for the liquefaction of the associated gas for a deep sea oil field. The design for the floating receiving terminal located in Southern Europe was developed by Fincantieri, while the SN Technigaz regasification process was based on submerged combustion vaporisers with a LNG storage capacity of 200,000 m3.

The transfer of LNG in open seas can be performed safely in a tandem loading configuration, using the Boom-To-Tanker. A large-scale model of this device was successfully tested, using motion data from basin tests. The project included both steel and concrete hull designs for the LNG FPSO.

Safety assessment of the various facilities of the floating LNG chain was performed under the supervision of BV and RINA. The necessary safety criteria can be met by combining current engineering practices from the offshore industry with those of onshore LNG terminals. Advanced computer tools were developed in order to address the liquid motion of the slack LNG storage tanks. It was found that sloshing was not an issue.