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Shell’s Prelude FLNG Project

Shell’s Prelude FLNG Project is the first floating natural-gas liquefaction facility in the world, operating on Australia’s west coast.

The challenge

As many natural gas reserves are located offshore, major Energy companies have started developing LNG plants installed onboard ships. Known as Floating Liquefied Natural Gas (FLNG) facilities, this is where extracted gas is treated and directly liquefied on board and transferred to ocean-going carriers to deliver it, ready to use, to the market.
Prelude, the first FLNG facility, was, at the time of completion, the largest offshore facility in the world, representing a significant engineering challenge for all contributing parties.

The project

We are proud to have contributed our Condensate Polishing Demineralization system, from design, construction, and supply, to commissioning and start-up.

The Condensate Polishing system removes traces of hydrocarbons in the recovered steam condensate, and the Demineralization unit produces ultrapure deionized water.
The mechanical and process designs were influenced by the installation site’s particularly severe conditions: a floating vessel that operates in an area subject to cyclonic events.
Our expert team developed specific construction solutions to be able to respect the process guarantees in the presence of significant wave motion.

The supplied packages were fully modularized to reduce the assembly time of the plants inside the ship’s hull. A considerable challenge consisted of the mechanical design of the structures that had to support the equipment’s weight and ensure stability during lifting, fitting, and operation with an overall weight of 150 tons and the capacity to withstand multidirectional accelerations.

The supplied solution

The Condensate Polishing system is designed to treat low-pressure condensate and guarantee continuous production of treated condensate. The system treats a flow rate of 71 ton/h of potentially contaminated heavy condensate: it is composed of 3 activated carbon filters, and each filter can treat 100% of the flow rate.

The Demineralization Package aims to remove dissolved salts from feed water composed of potentially contaminated hydrocarbons (PCH), normally clean condensate (NCC), and distillate water as makeup.

The Mixed Bed Exchange polisher package can treat a flow rate of 239 ton/h. It is composed of 3 mixed resin beds (3×50%). In regular operation, two are in service while the third remains in regeneration or standby mode.
The unit includes the following equipment for mixed bed regeneration:

  • Air blowers, including all necessary accessories for each air blower
  • Regeneration pumps, including all necessary accessories for each pump
  • Recycling pumps, including all necessary accessories for each pump

The introduction of regeneration chemicals is possible through caustic and acid injection pumps, diluted with demineralized water.