Cannon Artes contributed with two water treatment plants for the Shell project – Prelude, the first FLNG vessel operating on the Australian coast.
In the next twenty-five years, demand for natural gas world will grow even further. The new natural gas reserves to be exploited are mainly “unconventional” (shale gas) or in offshore fields off the coast.
The situation has prompted the major Oil & Gas companies to develop LNG plants installed on board of ships, known as Floating Liquefield Natural Gas (FLNG) – in which the extracted gas is treated and directly liquefied and transferred to ocean-going carriers, which will load the LNG, as well as other liquid by-products (condensate and LPG), and deliver them to the market.
The first FLNG facility in the world, owned by Shell, has been destined to satisfy the Asian market. It is the largest offshore facility in the world. If we compare its total length (top view) with the height of two commonly known skycrapers, it would be as high as the Taipei Tower 101, and more than half of the Burj Khalifa in Dubai.
It represents a major engineering project in which Cannon Artes was extremely proud to provide its contribution: design, construction and supply of two water treatment systems to feed the steam generators.
The system consists of a condensate treatment unit that removes traces of hydrocarbons present in the condensed steam to be recovered and a demineralization unit which produces ultrapure deionized water.
The mechanical and process design were influenced by the particularly severe conditions of the installation site: a floating vessel that will operate in an area subject to cyclonic events.
Thus, the materials selection had to be compatible with the severe process conditions because of the wide pH range and with the high humidity and salinity of the environment.
To reduce the assembly time of the plants inside the hull of the ship, the packages were supplied fully modularized.
A major challenge therefore consisted in the mechanical design of the structures that had to support the weight of the equipment and ensure stability both during lifting and fitting, with an estimated weight of 90 tons, and under operating conditions, with an estimated weight of 150 tons able to withstand multidirectional accelerations.
Cannon Artes developed specific construction solutions to be able to respect the process guarantees required by the customer even in the presence of significant wave motion.
The condensate polishing unit produces deoiled water through three granular activated carbon filters sized at 100% of capacity; two of them work in series while the other one is on stand-by, according to the “merry-go-round” scheme.
The demineralization system that treats the mixture of recovered condensate and desalinated water ensures a continuous production of 235 m3 /h of demineralized water. Three mixed-bed ion exchangers are installed. While two are working, the third one is standing-by ready to replace the first one that goes into regeneration. This process guarantees a specific conductivity of the demineralized water of less than 0,2 mS/cm.