Wärtsilä 8L20 main diesel-electric

Wärtsilä To Power Research Vessel
Advanced design work important to ship’s role: by ian cameron


Wärtsilä 8L20 main diesel-electric 

For one of the world’s most technologically advanced research vessels operating in ultra-sensitive environments, achieving low emissions of both noise and carbon dioxide will be critical to its success. The propulsion system of the planned new ship to be operated by the U.K.’s Natural Environment Research Council (NERC) is the focus of detailed and advanced design work by Wärtsilä, which has recently secured the contract to power the vessel. NERC is the U.K.’s main agency for funding and managing global research, training and knowledge sharing in environmental sciences, and its new vessel, to be built at the C.N.P. Freire S.A. shipyard in Spain, will be delivered by summer 2013, with a ship launch scheduled before the end of 2012.

It will replace the RRS Discovery which was built in 1962 and is coming to the end of its scientifically useful working life. The new vessel will take over the name Discovery and will be operated by NERC’s National Marine Facilities Division, based at the National Oceanography Centre in Southampton, England. The ship’s design will allow it to work in higher sea-states, complementing the work of NERC’s other research vessel, the RRS James Cook, NERC said. For the new vessel, much attention is being focused on the propulsion system to ensure that noise and carbon dioxide emissions are minimized. The contract for the propulsion equipment has been awarded to Wärtsilä, which will supply four of its eight-cylinder inline Wärtsilä 8L20 (nominally 1.6 MW each at 1000 r/min) main diesel-electric generating sets, two main propulsion steerable thrusters, one bow retractable thruster and a complete Low Loss Concept (LLC) diesel-electric system.

According to Wärtsilä, the LLC is a specially developed and patented diesel-electric system with reduced space and weight, higher redundancy and availability, reduced electrical losses and guaranteed low total harmonic distortion a measure of the distortion and noise in a power grid. Also, the LLC system allows an arrangement whereby all electrical components can be located in the switchboard room making installation, commissioning and operation more efficient. Another benefit is reduced short circuit levels, which means increased personnel safety, the company said.

Wärtsilä said it has experience in meeting the needs of specialist vessels including the supply of propulsion systems for research and naval ships with low underwater radiated noise (URN) requirements. For this vessel, special attention was paid to noise issues on the main steerable thrusters to meet low URN requirements. The shank and the pod were modified to give a more hydrodynamic shape and a special fixedpitch propeller design was adapted to the specific wake field of the ship. In addition, the generator sets will be double elastically mounted to ensure the “lowest possible vibration” is transmitted to the ship’s structure.

Wärtsilä added that a feature of the LLC is to remove the need for propulsion transformers and auxiliary systems. By removing these components’ electrical losses, fuel consumption and carbon dioxide emissions are reduced by at least 2% compared with traditional diesel-electric systems, Wärtsilä said. Three 8L20 double elastically mounted gen-sets each producing 1.52 MW at 1000 r/min, have previously been supplied for other research vessels such as the R/V Sarmiento de Gamboa, also built at C.N.P. Freire S.A. for the Spanish Scientific Research Council, and the R/V Cabo de Hornos, for the Chilean Navy.

Source: Diesel & Gas Turbine Worldwide

Leave a Reply