General Description
The cutter suction sand dredger is a stationary dredger equipped with a cutting device, which excavate the sand and soil before the slurry is sucked up by the dredge pump.
During operation the dredger moves around a spud pole by pulling and slacking on the two fore sideline wires. The cutter suction dredger is capable to dredge different kinds of material. It’s a high-efficient dredger type. The slurry is mostly transported by pipeline, but some dredgers do discharge to barge as well. The dredger cutter power is different depending on the type of soil to be cut.
The cutter head, cutter drive and the suction pipe are mounted on the ladder, is suspended by the pontoon and the ladder gantry wire.
Working Method
After the ladder of the cutter suction sand dredger has been lowered under water, the dredge pump(s) started and the cutter head set in motion. The ladder is then moved down until it touches the bottom, or until it reaches the maximum depth. The movement of the dredger round the spud pole is initiated by slacking the starboard anchor cable and pulling in the port side anchor cable or reverse. These anchor cables are connected via sheaves close to the cutter head to winches (dredging side winches) on deck. The pulling winch is called the hauling winch. The paying out winch ensures the correct tension in both cables, this being particularly important when dredging in hard rock
Application
Cutter suction dredgers are widely used in the dredging of harbours, land reclamation projects. The cutter dredger can tackle almost all types of soil, although this depends on the installed cutting power. Cutter suction sand dredgers are built in a wide range of types and sizes, the cutting head power ranges from 20 kW to over 1,000 kW. The max. suction depth can reach 25-30 m. The minimum dredging depth is usually determined by the draught of the pontoon.
The small to medium sized cutter suction sand dredgers can be demountable structure. This makes them suitable for transport by road to inland sites that are not accessible by water.
Advantages
The most powerful cutters can dredge hard solid continuously. The self-propelled CSDs can travel long distances and be deployed in remote locations, far from their home port, making them flexible to be used all over the world. They can work in shallow waters and they also have flexible discharge alternatives.
Small and medium size cutter suction sand dredgers can be dismountable and transportable over land. The hull is then comprised of a series of pontoons, with the one pontoon containing the machinery.
Main Components
- Dredger hull.
- Ladder.
- Pump unit.
- Power system.
- Hydraulic system.
- Cutter head.
- Spuds positioning and lifting system.
- Hoist and winches.
- Pipeline.
- Other equipment.
Design
When designing cutter suction dredgers, the following basic design criteria are important:
- Production capacity.
- Dredging depth.
- Discharge distance.
- Soil conditions.
The cutter suction sand dredger can be used in different kinds of water with soil, from soft clay, loose sand, solid sand and rock. The slurry to be dredged affected the design and construction a lot. Forces generated when working on the slurry soil. The forces are generated by the cutter head, transferred to ladder, winches, pontoon and spud. So the design of the cutter suction sand dredger is also determined by the installed cutting power.
When the soil with water conditions and the project schedule are known, we can calculate the required solid production per hour. The solid percentage to be dredged is usually 20-30% according to different soil conditions. Then we can get the mixed flow to be pumped and choose the suitable pump and drive power. The pump and power selection also have to consider about the discharge distance, pipeline material, diameter and discharge distance. The details have been mentioned in other articles of our website.
The maximum dredging depth is an important design parameter. Because in a cutter suction sand dredger the pontoon and the spud pole transfer part of the interplay of forces to the soil magnitudes of the moments that occur are proportional to the dredging depth. With increasing dredging depth, not only is the dredger larger and broader (for stability), it must also have a heavier construction. Moreover the dredging depth has a great influence on the design of the ladder construction and thus on the pontoon. After all it must be possible to raise the ladder above water for inspection.
Tai’an OCEAN Pump Co. Ltd. (referred to as OCEAN Pump)specializes in the development, production and sales of sand pump machine, sand dredging machine, jet suction dredger, cutter suction dredger , sand pump, submersible slurry pump, heavy duty sand pump, etc. As the leading sand dredging equipment designer, manufacturer and exporter, OCEAN Pump has been dedicated in supplying sand dredging machines to worldwide customers for over 20 years. OCEAN Pump has won the praise and trust of customers with rich industry experience, professional technology and excellent service.
