Clean Propulsion Concept for Broström Tankers

MAN B&W Diesel A/S, Alpha, Denmark has been awarded the contract to supply a twin medium speed main engine package to drive AziPull propellers for a series of 14,500 DWT Oil Products and Chemical tankers. MAN B&W Holeby GenSets will be supplied by a Chinese licensee. The vessels are under construction for Broström Tankers AB, Göteborg, Sweden.

Four vessels will be built by Jinling Shipyard, Nanjing, China. The newbuildings are scheduled for delivery during 2006 and 2007. Together with Broström Tankers AB, the naval architects and designers Skipskonsulent A/S, Bergen from the Vik & SandVik Group, Norway, have been in charge of this state-of-the-art shortsea tanker concept, optimized for North European trade. Transportation with maximum safety and minimal environmental impact have been given high priority with this design. The propulsion plant is based on twin, seven cylinder, MAN B&W L27/38 main engines and AziPull thrusters.

Auxiliary power is generated by four MAN B&W 6L16/24 GenSets. A total main engine output of 4,760 kW (6,470 BHP) will supply the propeller thrust, for a ship service speed of around 13 knots.

Maintainability

Furthermore, the twin configuration will make it possible to carry out maintenance on the propulsion system during the tanker’s regular trade. Immobilisation, repair and maintenance work could be carried out on one system with the ship alongside a terminal, with the other engine and propulsion system available in case of any need for the vessel to ‘take away’ from the quay.

Engines optimised for exhaust gas emission control

Main engines and GenSets will, from their turbochargers, lead the exhaust gasses to individual Munters SCR Converters/Silencers. The SCR converters are activated by injection of a solution of urea and water.

Imperative for the SCR converters’ full NOx reduction efficiency, which are specified to a NOx outlet content of max. 2g/kWh, is a relatively high and steady exhaust gas inlet temperature. For the main engines’ load range, with variable operation according to the propeller curve, a special turbocharger matching will be applied to control the exhaust gas outlet temperatures. For controlling the SCR process, including the injection of the urea/water solution at variable engine loads, the engines’ electronic speed and fuel index signals are used as input to Munters NO-analyser circuit.

Environment and ‘Clean Design’

The vessels will carry the DnV class notation ‘Clean Design’. This notation has requirements on, e.g., location of oil tanks, emission to air and water, capacity of specific equipment and documentation of systems as well as operational procedures.

All six diesel engines in the engine room will be fitted with catalysts for NOX reduction. This concept will make it possible to reduce the NOX emissions by 98%. Due to the fact that the vessels will spend 50% of their time in ports and terminals, the vessels will also meet requirements on low noise levels.

Environmental care has been a very important issue in the development and designing of the vessels. Propulsion redundancy and the cleaning of exhaust gasses are vital ingredients in this respect. Further environmental efforts have been made on technical solutions related to safety, cargo handling productivity and manoeuvrability.

A Large European tanker operator Broström Group operates 65 product and chemical carriers from 4,000 to 80,000 dwt, with an average age of seven years. It employs 37 tankers in European trade and transports more than 20 million tonnes of oil products per year. "By this new investment, Broström secures the position as being the largest provider of transportation services to customers in the European trade. Broström's capacity in product tanker shipping is covered, to a great extent, by Contracts of Affreightment. The design of the new ships and choice of features give Broström a competitive edge," States Broström CEO Lennart Simonsson.