Usage: Unloading of ships up to Post Panamax type and feeding onto trucks, railway wagons or quay side chain/belt conveyor
Single line ship unloaders
The use of mobile systems requires the availability of cranes to move the equipment into position. Also, the need to add the vertical pipes to the system requires a labour force to be in position 24 hours a day. In order to get a better overall performance with less operational expense, shipunloading systems such as the Multiport are used. These unloaders normally have a peak capacity of up to 600 t/h. They can be powered via electrical cable or by diesel generators and can be fixed or self-propelled on rails or rubber tyres.
The use of horizontal and vertical telescopic pipes allows a big area of the unloading hatch to be reached. With an auxiliary winch attached to the boom, a payloader (bobcat) can help the clean up operation in the ship's holds.
Figure above shows five Multiport type unloaders discharging a ship into quayside trucks and rail wagons. One of them is used as a "floater" i.e. it can be moved around easily, because it is mounted on rubber tyres. This rubber tyred "floater" can move to any location to help in the discharging as required. It is a 4-wheel steerable unloader and can avoid dead time by travelling quickly in curves. Characteristic of this type of equipment developed in the last few years include:
- Environmental protection
- Short delivery time - standardisation
- Maintenance and protection
The Multiports, for example, are equipped with filters which capture the dust from the products being handled. One special type of filter cleaning system has shown to be the most adequate is the reverse flow generated by a blower. It uses the same air of the filter (same temperature and density), thus avoiding water condensation and blockage of the filter bags. Also, filter bags can be cleande by air blasts generated by an air compressor with an air dryer needed to avoid the mentioned water condensation. Today, the sound insulation in this equipment is standard and its use in ports close to residential areas is becoming more and more acceptable.
Short delivery time - standardisation
The Multiport unloader has a short delivery time because all swivelling parts are standardised, even the gantry if a rubber wheel type is required. With the use of rails, the design and necessary engineering takes some more time. A rail unloader will normally require longer delivery time depending the integration with the local conditions and, if in stock, rubber tyred with generating set unloader.
Maintenance and protection
Multiport unloaders offer electrical and mechanical protections such as:
- Electrical panel with PLC and troubleshooting lamps
- Limit switches
- Over and underload protection
- Protection of rotating parts
- Easy access to checking points
The possibility of lowering the boom to the ground offers a considerable advantage because inspection and substitution of parts - wearing plates of the elbow, winches and cable pulleys etc. - are made on the ground, making careful inspection very easy, and any dangerous work high above the ground is eliminated.