Jan De Nul Group has ordered three 3,500m³ trailing suction hopper dredgers from Keppel Singmarine.
The design of these vessels is based on the 3,400m³ TSHD Alvar Nuñez Cabeça de Vaca and Sebastiano Caboto, built in 2011, and successfully operating since.
The vessels combine a shallow draught with high manoeuvrability, making them very suitable for working in confined areas, Jan De Nul said.
The vessels are in diesel-electric execution: all major drives (thrusters, dredge pump, jet pumps etc) 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 we ensure that the load is optimally distributed over the diesel generator sets. All these measures result in a low fuel oil consumption, which is the best in its class,” Jan De Nul said.
Exhaust gas treatment system
Thanks to the low fuel oil consumption emissions are lowered, but in addition the vessels are 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 normally available fuel oil, and the exhaust gases are 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 (NOx, SOx, Particulate Matter, CO and Hydrocarbons) will comply with EU Stage V, and be better than any other vessel or dredger, the company said.
Hopper capacity: 3,500m³
Deadweight: 5,500 tonnes
Length o.a.: 89.3m
Max. dredging depth: 27.6m
Suction pipe diameter: 800mm
Pump power (trailing): 1,250kW
Pump power (discharging): 3000kW
Propulsion power: 2x1100kW
Total installed diesel power: 5,510kW
Accommodation: 16 persons