MAN B&W diesels for "clean design" products/chemical 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 at Jinling Shipyard, Nanjing, China. The newbuildings are scheduled for delivery during 2006 and 2007.

Transportation with maximum safety and minimal environmental impact have been given high priority with this design, which is the work of Broström Tankers and naval architects and designers Skipskonsulent A/S, Bergen, part of Norway's Vik & SandVik Group, Norway,

Powered by MAN B&W Diesel engines
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.

The redundancy obtained by twin main engines with independent fuel systems and twin propulsors, with independent steering, leads to extended service reliability and scheduling dependability, as well as a very high degree of operational safety.

The twin configuration will make it possible to carry out maintenance on the propulsion system during the tanker's regular trade. Immobilization, 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 move away from the quay.

Engines optimized for exhaust gas emission control
Exhaust gases will be led from the turbochargers of the main engines and gengets to individual Munters SCR Converters/Silencers. The SCR converters are activated by injection of a solution of urea and water.

A relatively high and steady exhaust gas temperature is needed for the SCR converters to achieve full NOx reduction efficiency--specified as a NOx outlet content of max. 2g/kWh. A special turbocharger matching will be applied to control the exhaust gas outlet temperatures for the main engines' load range, with variable operation according to the propeller curve.

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.

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 for 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 maneuverrability.

Principal Particulars
Length 146 m

Breadth 22 m

Draft 8 m

Deadweight 14,500 tonnes

Cargo capacity 18,700 cu.m

Speed 13 knots