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Jan de Nul orders trio of trailers with exhaust gas treatment systems

New Vessels // March 15, 2017

Jan de Nul's new trailers will have exhaust gas treatment systems.

Jan De Nul Group has ordered three 3,500m3 trailing suction hopper dredgers, which will be built at Keppel Singmarine.

The design of the vessels is based on the 3,400m3 trailers Alvar Nuñez Cabeça de Vaca and Sebastiano Caboto, which were built in 2011. The vessels combine a shallow draught with high manoeuvrability, making them suitable for working in confined areas.

The vessels are diesel-electric: all major drives (thrusters, dredge pump, jet pumps) are electrically driven and controlled by means of frequency converters. In this way each system can operate at its optimal speed and power.

Power is generated by means of three diesel generator sets; a control system automatically starts and stops the sets depending on the power requirement, and by means of asymmetric load sharing ensure that the load is optimally distributed over the diesel generator sets. All these measures result in low fuel consumption.

Thanks to the low fuel oil consumption emissions are lowered, but in addition the vessels will be equipped with exhaust gas treatment systems in order to further reduce harmful emissions.

New vessels need to comply with IMO regulations for NOx emissions. As the new dredgers will frequently operate in estuaries and on rivers, or near the coast, and therefore near residential areas, Jan De Nul Group decided to limit the NOx emissions to a level far below the actual requirements, and to reduce other contaminants that are currently not regulated by IMO.

The new vessels will operate with fuel oil and their exhaust gases will be cleaned by means of a Selective Catalytic Reduction (SCR) system and a Diesel Particulate Filter (DPF).

The SCR system lowers the amount of NOx in the exhaust to a level corresponding with the future European (EU Stage V) requirements for inland waterway vessels; this standard is much more stringent than the applicable IMO Tier II and Tier III requirement.

The DPF removes particulate matter from the exhaust, down to a level in accordance with the future EU Stage V requirement for inland waterway vessels.

Combined with the use of readily available low sulphur fuels, the emissions from the vessels will comply with EU Stage V and, claims Jan de Nul, be better than any other vessel or dredger. They will be equivalent or better than those of a dredger using LNG as fuel, but, by using normally available fuels, compared to the limited availability of LNG, lower emissions will be achieved worldwide, all of the time.

The vessels will be 89.3m long with a hopper capacity of 3,500m³. They will have a deadweight of 5,500 tonnes and maximum dredging depth of 27.6m. They will have a suction pipe with a diameter of 800mm and a speed of 11.3 knots. Pump power (trailing) will be 1,250 kW; pump power (discharging) will be 3,000kW; propulsion power is 2 x 1,100kW. The total installed diesel power is 5,510kW. The dredgers will have accommodation for 16 people.

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