In future, the 95 m special ships will be used in the North and Baltic Seas to deal with accidents, fires, or vessels that are unable to manoeuvre. 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. Once complete, they will replace 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.
According to the statement, the two ships are powered by gas-electric propulsion systems based on four medium-speed Bergen B36:45L6AG units from Rolls-Royce, each of which delivers 3600 kW. Rolls-Royce is not only an engine and generator supplier, but also a 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.
Christian Prinz, Rolls-Royce project manager, said: “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.”
With the system developed by Rolls-Royce, the engine power output is adjusted in relation to the amount of gas in the intake air. In other words, 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.
Knut Müller, Vice President Marine at Rolls-Royce, said: “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.”
Carsten S. Wibel, head of Abeking & Rasmussen Special Vessels GmbH, added: “Rolls-Royce was the only manufacturer worldwide able to utilize its long-standing experience in this specialized field and develop gas protection for straightforward gas engines, all in line with our schedule requirements and backed up by the relevant feasibility study.”
According to the statement, the two predecessor vessels named earlier were likewise powered with MTU-brand engines from Rolls-Royce. Jörg Fischer-Felsberg, Director of Sales and Service for MTU products in Germany, commented: “The customer was impressed not only by MTU propulsion, but by the quality of the service we provided, and that swayed his decision in our favour.”
In an emergency, the new ships, which are capable of speeds of more than 15 knots, will be at the accident scene in no more than two hours. Equipped with emergency towing capabilities with 145 t 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, these vessels are capable of being used in the most challenging missions. The entire ship – not just the engines – is gas-protected. If the ship 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. Rolls-Royce claims that the resulting overpressure ensures that no more toxic air can enter.
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 governmental 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 this year, a decision will be made regarding whether a third, identical vessel should be constructed or not. The two ordered so far are scheduled to enter service in 2023 and 2024.
Read the article online at: https://www.lngindustry.com/liquid-natural-gas/01042020/rolls-royce-supplies-propulsion-system-for-new-multi-purpose-vessels/