Pumps for Suction Dredgers in the Atlantic

The pumps will be employed on a trailing suction hopper dredger with suction pipe set to operate in the Atlantic near the mouth of the Loire estuary. The ship has been designed to operate with waves that are up to seven metres high, while its hoppers can load around 2,000 cubic metres of sand and gravel. An articulated suction pipe helps the dredge pump to suck slurry from a depth of up to 45 metres. The pump utilised for this purpose is manufactured by KSB’s US subsidiary GIW in Georgia; it handles flow rates of 7,000 cubic metres per hour and develops heads of approximately 30 metres. Its impeller has a diameter of 1.25 metres and is used to pump a sand-gravel-water mixture with a density of up to 1.4 tonnes per cubic metre. The pump casing, impeller and liner alone weigh approximately 9000 kilogrammes. Once the ship’s hopper is filled with sand, it sails to a wharfage where a second pump, also manufactured by GIW, discharges the sand and gravel mixture onto the shore via a 500 metre discharge pipe. The pump weighs around 20 tonnes and has an impeller diameter of more than 1.5 metres. Its maximum flow rate is around 6.200 cubic metres per hour. The impellers and casings of both pumps are made from corrosion-resistant and abrasion-resistant white cast iron with a chromium content of 27 percent. The scope of supply totalling several hundred thousand euros includes a water jet pump and two drainage pumps. KSB was awarded the contract thanks to its ability to supply pump sets capable of handling slurries with a sand concentration of 40 percent while achieving an efficiency of 80 percent. From a technical and cost-efficiency point of view, this offered the operator the best solution.