Self-Unloading Bulk Cargo Ships
The "Moving Hole" feeder can be made 30 m+ long, which makes it well suited for self-unloading bulk cargo ships and barges. The multiple slot arrangement enables high discharge to be obtained with relatively low power requirements and low maintenance.
For ships and barges, "funnel flow" hopper design is used to maximise storage capacity and at the same time, have a self emptying hopper without manual intervention. As the "Moving Hole" feeder is fully "effective" over the full outlet irrespective of length, the critical piping dimension for a long hopper is exceeded by a wide margin, even for difficult flowing materials. Conventional gates separated by "hog-backs" commonly used on ships are prone to "rat-holing" as the effective outlet dimension is too small for many cargoes.
Unloading of a ship or a barge can to a large degree be automated. A consistent rate of unloading without hang-ups allows the conveyors to unload at optimum capacity.
The "Moving Hole" system in addition offers a number of advantages over conventional gates commonly used.
Advantages of Unloading Bulk Cargo Ships and Barges
- Absence of hog backs means that the valley angles are limited to ends of the holds only. In addition, effective discharge by the "Moving Hole" feeder allows the hopper slope to be reduced by several degrees while still have a self-emptying system. The increase in cargo storage volume is appreciable.
- The "Moving Hole" feeder will provide reliable discharge of cargo without hang-ups. Vibrators or other flow promoting devices commonly required with gates are not needed. More efficient unloading means faster turn around time for the ship. The system is capable of handling more difficult flowing cargoes than is possible with the conventional gates.
- Consistent metered discharge by the feeder means that the tunnel conveyors do not have to be oversized to handle surges, as is the case with gates. This will result in some savings in cost of the conveyors. Also, the receiving facility on the shore will operate more smoothly, resulting in more efficient unloading.
- A receiving hopper on the shore (if not already available) is not needed as the feed rate can be set to match the conveying capacity on land.
- The "Moving Hole" feeder system can be operated with relatively simple controls, as the discharge rate is dependent only on the feeder speed. A more sophisticated control system would be required on gates if fully automated.
- Tunnel men are required to operate gates system if not fully automated.
- Dusting is considerably lower with the "Moving Hole" feeder compared to gates. This dust can also be fully contained.
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