Wartsila has introduced a new Upgrade Kit for Slow Steaming for RTA and RT-flex low-speed engines to enable shipowners and operators to make major savings in fuel costs while slow steaming their ships. The Upgrade Kit allows Wartsila low-speed marine engines to be operated continuously at any power in the range of 20% to 100%. This means that with the Upgrade Kit ships can sail continuously at sea speeds down to some 60% full speed.
High bunker prices have put fuel efficiency high on the agenda of charterers, shipowners and ship operators. There is thus considerable interest in slow steaming that is operating ships for long periods at reduced sea speeds. Yet without modification with this Upgrade Kit, there is increased risk of engine fouling and excessive component temperatures when operating continuously below 50% engine load. The Upgrade Kit overcomes such problems, enabling the engines to operate continuously at powers down to 20% of their full installed power. The modified engine is not permanently derated but can operate at any time up to its full installed power. Owing to the characteristic power versus speed relationship of ship propellers, this extended operational power range enables ships to be sailed at sea speeds down to some 60% of full speed.
The first Upgrade Kits were ordered in November 2008 by the German owner Koepping Shipping Company for two container vessels, each with a single 8-cylinder Wartsila RTA62U engine. The two ships, "Aglaia" and "Lantau Arrow", are 1200 TEU fast feeder container vessels. They have a maximum speed of about 22 knots at design draft with the main engines delivering 15,000 kW at 107 rpm.
Joerg Koepping, Managing Director of Koepping Shipping, said "The Slow-Steaming Upgrade Kits will give these ships considerable flexibility to adapt to the present difficult market conditions, allowing great cost savings while slow steaming but retaining the capability for full speed whenever necessary."
The Upgrade Kit is available for all RTA and RT-flex engines with multiple turbochargers. For ships that must comply with the IMO NOX emissions regulations, the restrictions imposed by the emissions limits will be evaluated in each case and a customized turn-key package may be offered. RTA and RT-flex engines can be safely operated continuously at loads above 50% of the contracted maximum continuous rated (CMCR) power without any modifications.
The concept of the Upgrade Kit is to cut out a turbocharger when the engine is to be operated at low load. This increases the scavenge air delivery at low load for better combustion and more optimum temperatures of engine components. The cut-out point depends upon the engine configuration.
The Upgrade Kit involves fitting shut-off valves in the exhaust duct before the turbocharger turbine and in the scavenge air duct after the compressor, together with a bypass line to keep the turbocharger rotor spinning at a preset constant speed. The valves are remotely operated and the Kit includes fitting a control system to operate the valves.
The Upgrade Kit is delivered by Wartsila on a turn-key basis and includes engine performance analysis, cabling and installation, all materials and their transport, service engineers to undertake the whole installation and commissioning, and emission measurement and certification. The installation and commissioning of the Upgrade Kit can be completed during normal commercial operation of the ship and during normal port calls.