Alfa Laval PureSOx scrubbers with shared WCS installed on world’s largest containership

Two PureSOx scrubbers with a shared water cleaning system (WCS) installed on the 23,992 TEU boxship Ever Ace have proved their effectiveness, according to Swedish company Alfa Laval.

In July 2021, Ever Ace, believed to be the world’s largest container vessel, set sail from South Korean shipyard Samsung Heavy Industries. The giant ship is owned by Taiwanese shipping company Evergreen Marine Corporation.

Cleaning to match 80 MW of engine power Ever Ace is the first of twelve vessels planned for Evergreen’s A Class, which comprises container vessels of nearly 24,000 TEU capacity.

Powered by a massive main engine of nearly 60 MW, it also has five auxiliary engines of 4.5 MW each.

To clean the engines’ exhaust gas, the Ever Ace has two PureSOx scrubbers on board – one for the main engine and one for the auxiliaries.

As hybrid scrubbers that can operate in open or closed loop, they require effective cleaning of the closed-loop circulation water. This is provided by a shared WCS based primarily on high-speed centrifugal separation.

Expanding capacity, not size

Alfa Laval’s WCS design was recently updated, providing additional modular options.

On vessels with high engine power, such as mega-container vessels, it allows for greater capacity by adding flocculation to the centrifugal separation at its heart.

This is the case on the Ever Ace, where the WCS incorporates three high-speed separators, flocculator modules and a feed pump. Though it serves two PureSOx scrubbers with a combined exhaust gas cleaning capacity of almost 200 t/h, the WCS has a minimal footprint in relation to its high efficiency.

Performance confirmed at sea

Just as the Ever Ace is the first in its class, the shared WCS was the first with the new design to be commissioned by the PureSOx team.

The limited gas load during a short shipyard sea trial was not enough to test the full WCS cleaning capacity, so Alfa Laval experts followed Ever Ace during a September journey from the UK to Germany and the Netherlands.

This provided time for a more thorough WCS evaluation, as well as for crew training and the resolution of open items after leaving the shipyard, according to Alfa Laval.

Along the route, the WCS could be observed during longer periods with high engine loads. Cleaning performance was high throughout the voyage, even when much larger amounts of circulation water reached the WCS.

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