Why Dredging Vessels Rely on Körting Ejectors
Dredging is one of the most demanding marine operations. Discover why ejectors have become the preferred technology for handling abrasive slurries, priming pumps, and creating vacuum on board modern dredging vessels.
Dredging vessels operate in some of the harshest conditions in the maritime industry. Whether deepening shipping channels, reclaiming land, or extracting minerals from the seabed, the equipment on board must handle enormous volumes of water, sand, clay, and rock — often around the clock for weeks at a time.
Why Ejectors for Dredging?
An ejector — also called a jet pump — uses the energy of a high-pressure motive fluid to entrain and transport a secondary fluid or slurry. Unlike mechanical pumps with rotating parts, ejectors have no moving components in the flow path. This fundamental design difference gives them several decisive advantages in dredging.
No Moving Parts, No Downtime
Dredged material is highly abrasive. Sand and gravel rapidly wear impellers, seals, and bearings in conventional pumps. Ejectors, by contrast, are static devices. Their wear rate is dramatically lower, and when wear does occur the affected nozzle or diffuser section can be replaced quickly without dismounting the entire unit.
Handling Solids Without Clogging
The open flow geometry of an ejector allows large particles and debris to pass through without blockage. Mechanical pumps often require screens or grizzlies upstream, adding complexity and maintenance. Ejectors eliminate that problem at the source.
Types of Ejectors Used on Dredgers
- Water-jet ejectors for priming centrifugal dredge pumps
- Steam or water ejectors for creating vacuum in hopper overflow systems
- Slurry ejectors for boosting transport through long discharge pipelines
- Air ejectors for degassing and removing entrained air from pump casings
Advantages Over Mechanical Pumps
In a traditional dredging setup, mechanical pumps handle the heavy lifting. They work well under steady conditions, but dredging is anything but steady. Feed material changes constantly — from soft silt to compacted clay to gravel — and flow rates swing with the cutting head position and suction depth.
- Reliability: no seals, bearings, or impellers to fail
- Abrasion resistance: replaceable wear parts, simple geometry
- Cavitation-free operation: ejectors do not suffer from NPSH limitations
- Compact installation: no foundation or alignment needed
- Low maintenance: typical overhaul intervals 5–10× longer than mechanical pumps
Körting's Track Record in Dredging
Körting Hannover has supplied ejectors to the dredging industry for over 50 years. Their product range includes standard units for common applications as well as custom-engineered solutions for extreme duties — such as ejectors rated for 2,000 m³/h of slurry at solids concentrations above 30%.
As Tas & Company, we are Körting's exclusive representative in the Benelux region. We support dredging contractors with sizing, selection, and after-sales service — from initial enquiry to commissioning on board.