Overview
Dredging operations use cutter suction dredgers (CSD), trailing suction hopper dredgers (TSHD) and sand dredgers to remove sediment from waterways and deliver slurry via floating pipelines to discharge zones. Slurry density (i.e. solids content in the discharge line) is the key parameter for production monitoring, pump speed control and blockage prevention. Major operators such as Royal IHC, Jan De Nul and CCCC dredging fleets all rely on inline density meters for real-time discharge monitoring.
Process challenges
- Highly abrasive slurry with variable grain size — wears out intrusive sensors quickly
- Radioactive density meters face strict shipboard licensing and cross-border port restrictions
- Large pipeline diameters (DN500–DN1000) demand non-intrusive measurement to avoid pressure drop
- Vessel motion, temperature swings and entrained air require robust signal stability
- Pump-blockage risk demands fast density-gradient alarms and interlock signals
Recommended solutions
| Measurement point | Principle | Models |
|---|---|---|
| CSD / TSHD discharge main | Ultrasonic acoustic impedance (clamp-on) | PS7000 |
| Sand dredger discharge | Ultrasonic acoustic impedance | PS7000 |
| Reclamation inlet manifold | Ultrasonic acoustic impedance | PS7000 |
Key advantages
- Non-nuclear replacement — direct substitute for Cs-137 / Co-60 density meters; eliminates radiation licensing, port inspection delays and dedicated radiation-safety officers
- Clamp-on installation — sensors mount externally; no pipe penetration, no wetted-wear parts, no impact on pressure rating
- Gas / scale immunity — multi-frequency ultrasonic compensation outperforms differential-pressure methods when slurry contains entrained air or builds wall scale
- Blockage alarm — fast density-gradient detection with 4-20mA / RS485 / HART output feeds straight into the vessel DCS for pump speed interlock