Coal Handling
Offshore Transfer Terminals
07.03.2008 | Author / Deskman: MacGregor Bulk AB / Marcel Dröttboom
Flexibility in location and capacity is among the key benefits of self-unloading systems, which offer reliable, efficient and environment-friendly solutions to logistics problems in bulk shipping.
The size of a ship that can be deployed on a specific route is often limited by draught restrictions in the discharging port. Today’s transshipment technology allows charterers to bypass the problem of such restrictions, as well as ports that lack sufficient discharging installations, and ensure that Capesize tonnage can be used and loaded at higher rates, explains Jonas Johansson, sales manager, MacGregor Bulk AB, Sweden.
In May 2005, MacGgregor Bulk AB (formerly BMH Marine) secured a contract to supply Nordstroms bulk handling systems for the floating offshore transfer barge terminal Spencer Gulf and two 10500 dwt self-unloading barges, Barnagarla and Middleback, each with an unloading capacity of 5000 t/h.
Built in Chinese yards for Shanghai CHEC Equipment Engineering, the three barges entered service in February 2007 with CSL International at Whyalla, South Australia, where they are engaged in transferring material from the port to Capesize bulk carriers in the open sea.
Spencer Gulf is towed out to sea and moored alongside the receiving bulker, while the first self-unloading shuttle barge is loaded with ore in the port before being taken out and moored to the transfer terminal. The barge cargo is then transferred – by the barge’s own conveyor system – to the terminal for loading onto the Capesize bulker at 5000 t/h.
Using two alternating shuttle barges - one loading in port, the other unloading offshore - achieves a fast and efficient transfer of ore from shore to ship.
Special attention was paid to meeting strict Australian regulations on environment-friendly cargo handling during transloading operations. Dust emissions in the offshore phase are curbed by a totally-enclosed conveyor system and shuttle boom, the latter also equipped with dust collectors.
Further reducing dust during transloading, spray water nozzles are fitted in the discharge chutes between conveyors and in the unloading points.
The floating offshore transfer terminal Spencer Gulf is a flat-top barge equipped with a Nordstroms bulk handling system and incorporating a deck hopper, into which cargo is transferred from the shuttle barges. From there, the ore is conveyed onto two inclined belt conveyors that access a slewing and hoisting telescopic boom conveyor arranged midships for loading the cargo holds of the receiving bulk carrier.
Operation and control of the transloading process – from shuttle barge via Spencer Gulf to the bulker holds – is remotely controlled from a station on the transfer terminal.
The two flat-top shuttle barges are also each equipped with a Nordstroms self-unloading system and a large deck hopper, which is loaded from the shoreside loading system. Unloading is effected by gravity flow when the hydraulically-operated basket gates are opened at the bottom to feed cargo to the longitudinal conveyor belt.
Cargo is then conveyed by this belt to a slewing and hoisting boom conveyor for transfer to the receiving hopper of the offshore terminal Spencer Gulf. The entire conveyor system is monitored via remote control, either from the control room of the shuttle barges or from Spencer Gulf.
Moving the transshipment process from a port terminal to the open sea using an offshore transfer facility offers significant advantages to all parties:
- reduced pollution in ports and their immediate environs
- arger ships can replace a higher number of smaller vessels on fewer voyages?
- the low draught of the shuttle barges avoids expensive dredging in port?
- he high capacity of the system cuts time spent in port, a great benefit for charterers and the local environment.?
Another merit is the comparative ease of meeting any future demand for increased capacity by deploying additional offshore terminals and barges; alternatively, the original facilities can be moved when the need arises to support a similar venture at another port.
MacGregor Bulk AB
Taiwan Power orders another two MacGregor coal unloaders
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