Aframax tanker design from Wärtsilä

22 Oct 2012
Rendering of the Wärtsilä Ship Design low-emission Aframax tanker concept

Rendering of the Wärtsilä Ship Design low-emission Aframax tanker concept

Wärtsilä Ship Design has announced a new design for an Aframax-size tanker that focuses on efficiency, and is said to offer solutions for current and forthcoming emissions legislation.

The 253.2m length oa, 44m beam double hull, single screw crude oil tanker features a hull form that is CFD-optimised for flow lines and pressure distribution along the hull, which is intended to provide less resistance with higher propulsion efficiency. Minimum time spent at terminals is enabled by a loading/discharge rate of 9,000m³/h. A cylindrical-format bow accommodates a range of operational draughts in varied weather conditions. Carrying capacity will be about 117,000dwt, with 134,250m³ of cargo in 12 tanks

The main engine is a two-stroke Wärtsilä X62 electronically controlled, common-rail type with extra long stroke and low rpm. It has a minimised physical width to allow a slimmer aft body design, which the company says further benefits the propulsion efficiency. The engine is claimed to offer 7% fuel savings compared with a conventional engine for this specific design. The same vessel speed can be reached using fewer cylinders, in this case six instead of seven. Using a seven cylinder version could provides even greater efficiencies due to the lower rpm and higher de-rating.

Emission control is achieved through an integrated exhaust gas scrubber in the funnel, to reduce SOx emissions from the main engine, auxiliary engines and auxiliary boilers, while NOx emissions are minimised with a SCR system before the main engine turbocharger. The scrubber allows the ship to meet 0.1% sulphur limits even when burning 3.5% sulphur HFO. The abatement equipment is tuned with the main and auxiliary engines for effective operations across the complete load range and IMO Tier III requirements can be fulfilled.

“The new realities of the shipping industry call for higher fuel efficiency, lower operating costs, and better environmental performance. The new Wärtsilä Aframax tanker design meets all these criteria, and we are proud to offer this segment the combination of state-of-the-art design and superb propulsion machinery that can produce meaningful savings,” said Riku-Pekka Hägg, vice-president Wärtsilä Ship Design.

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