Rolls-Royce is supplying the gas-shielded propulsion system for two new multi-purpose vessels to keep them operational even under difficult conditions.
In future, the 95m special ships will be called out on the North and Baltic Seas to deal with accidents, fires or unable-to-manoeuvre vessels. They are being built for the German Federal Waterway and Shipping Administration by Abeking & Rasmussen, the ship and yacht yard based in Lemwerder, Lower Saxony.
The vessels are replacing their predecessors, the Scharhörn and Mellum, after 46 and 36 years of service respectively. The ship technology division of the Federal Waterways Engineering and Research Institute was commissioned with planning, design and tendering and now with construction management.
The two ships are powered by gas-electric propulsion systems based on four medium-speed Bergen B36:45L6AG units from Rolls-Royce, each delivering 3,600kW. Rolls-Royce is not only engine and generator supplier, but provider of a special solution in the form of the gas protection specially developed to allow the engines to remain operational even if, for example, the ambient air has been contaminated with explosive gases following a gas tanker accident. “Obviously the engines are there to burn gas, but if gas gets into the combustion chamber in an uncontrolled way via the intake air, the engine will become unmanageable,” explained Rolls-Royce project manager Christian Prinz. With the system Rolls-Royce has developed, the engine power output is adjusted in relation to the amount of gas in the intake air. In short, the more gas there is in the intake air of the engine, the less gas fuel is fed to the engine via the gas control valves. If the gas volume is too high, special quick-acting flaps shut off the intake of gas and air and the engine comes to a stop.
In the event of an emergency, the new ships, capable of speeds over 15 knots, will be at the accident scene in no more than two hours. Equipped with emergency towing capabilities with 145 tonnes bollard pull, chemical tanks, an explosion-proof safety and container cargo hold, as well as oil collection equipment such as skimmers, oil-holding tanks and a separation room, they are able to accomplish the most challenging missions. Not only the engines, but the entire ship is gas-protected. If it enters a dangerous zone in which there are flammable or health-endangering substances in the air, the crew must switch the ship to gas-protection mode, meaning that windows and doors must be sealed gas-tight. This creates a citadel into which clean air is pumped. The resulting overpressure ensures that no more toxic air can enter.
“With these ships, we’ve combined the decades of experience we have under our belt in the field of medium-speed gas engines from Rolls-Royce with our highly specialised gas protection expertise to create an effective solution for our customer,” said Knut Müller, Vice President Marine at Rolls-Royce. Indeed, Rolls-Royce is the only manufacturer worldwide able to supply such powerful engines with gas protection and the relevant certification. They have already proven their worth in sea rescue cruisers, pollution control vessels and most recently in the Nordic, the North Sea emergency tug. Rolls-Royce has been supplying medium-speed gas engines for over 20 years.
“Rolls-Royce was the only manufacturer worldwide able to utilise its long-standing experience in this specialised field and develop gas protection for straightforward gas engines, all in line with our schedule requirements and backed up by the relevant feasibility study,” pointed out Carsten S Wibel, head of Abeking & Rasmussen Special Vessels.
That gas engines are being used in this project is owing to a German government directive that requires a massive reduction in CO2 emissions from government vessels. Enak Ferlemann, Parliamentary State Secretary to the Federal Minister of Transport and Digital Infrastructure, said, “With the new LNG-powered ships that also carry the Blue Angel environmental certificate, we’re simultaneously ensuring top safety and top environmental standards in high-tech shipbuilding.”
By the end of 2020, a decision is to be made as to whether a third, identical vessel should be built. The two ordered so far are to go into service in 2023 and 2024.