Wärtsilä completed retrofitting its first commercial marine scrubber for treating exhaust emissions from a ship’s main engine this August. Installed on the M/S Containerships VII, the unit will enable the vessel to meet future SO_x emission requirements in Sulphur Emission Control Areas.

The 13,965 dwt M/S Containerships VII was fitted with a Wärtsilä marine scrubber to treat exhaust emission from its main engine, a Wärtsilä W7L64 unit, in August. Photo courtesy of Wärtsilä.

To minimise downtime and incorporate installation with the Containerships VII’s annual docking, the prefabrication of components, the scrubber tower, the equipment container, and piping began in April.

Scrubbers represent a major step forward in bringing advanced emission control technology to the maritime world – and Wärtsilä is the first manufacturer to have been awarded a Sulphur Emission Control Area (SECA) Compliance Certificate by Det Norske Veritas and Germanischer Lloyd.

Drawing on the company’s extensive experience in developing and delivering scrubbers for stationary diesel power plants, the Wärtsilä marine scrubber is a fully integrated system designed to offer optimal lifecycle efficiency and complies with the new International Maritime Organisation (IMO) guidelines for treating exhaust emissions from all 2- and 4-stroke engines, as well as oil-fired boilers.

The scrubber works with fresh water boosted by NaOH to create a strong alkaline solution, which neutralises SO_x content to sulphates in the scrubbing water. A small amount of bleed-off, extracted from the scrubbing water, is fed to a bleed-off treatment unit. Clean effluent, fulfilling all the quality and monitoring requirements stipulated by the IMO, can then be discharged.

Tests involving a full-size scrubber installed on board the MS Suula, a 14,665 dwt tanker owned and operated by Neste Oil, demonstrated a SO₂ removal rate exceeding 99% in all operating conditions, even when using high-sulphur fuel and throughout the load range. The scrubber also removed 3-7% of NO_x and 30-60% of particulate matter.

Wärtsilä is a global leader in complete lifecycle power solutions for the marine and energy markets. The company booked net sales totalling €4.6 billion in 2010 and employs 17,500 people in 160 locations in 70 countries around the world. For more on the company, see our latest article or visit their Web site.

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