PureBallast, Alfa Laval’s chemical-free system for ballast water treatment developed in cooperation with Wallenius Water, will be installed aboard two new bitumen tankers for Nynas, a supplier of specialty petroleum products. It is the first ballast water treatment installation adapted to the hazardous tanker environment. Nynas, a specialist in naphthenic oils and one of Europe’s leading suppliers of bitumen, has chosen PureBallast for two bitumen tankers to be built at China’s Wuhan Nanhua Huanggang Jiangbei Shipyard.
Scheduled for delivery in 2010, the Nynas vessels will each have a ballast tank capacity of 2150 m3 and a treatment system flow of 500 m3/h. But in light of their cargo and the resulting gas risks on board, the vessels will have their PureBallast systems above deck rather than below. The ballast water treatment solution, which involves a specially designed enclosure, is the first to be certified for use aboard petroleum tankers.
Even after Nynas had chosen PureBallast, the system had to be adapted to the hazardous environment of a bitumen tanker. As well as releasing gases, bitumen is normally transported at a temperature between 160-180ºC but vessels can carry products up to a temperature of 250ºC. Such conditions have thus far prevented ballast water treatment on tankers, since no ballast water treatment system has yet been classified as EX-proof.
To facilitate adaptation and simplify dialogue with the shipyard, Alfa Laval spent considerable time working with Nynas and the Shipyard. Besides travelling to China to present the PureBallast technology, Alfa Laval representatives arranged for both parties to visit PureBallast installations currently underway.
The finished design for the Nynas tankers places PureBallast in a pressurized structure on deck, rather than in the engine room. With a double-door construction that acts as an airlock and an over-pressurized ventilation system, the housing eliminates the need for an EX-proof treatment system, allowing PureBallast to be certified by Bureau Veritas for use in this environment.