Grappling with a choice of grab unloaders
All grab-type ship unloading systems have differing strenghts and weaknesses. Dockside grab discharge of dry bulk cargo can either be carried out by high-capacity, purpose-built grab gantry unloaders or by lower-capacity (generally), but more versatile slewing cranes, whether fixed, rail-mounted, rubber-tyred or pontoon-mounted.
Mobile harbour cranes have long played an important role in mainstream bulk handling. For smaller ships and barges, the “new generation” of mobile (or rail-mounted) hydraulic unloaders, featuring a grabber device attached via a flexible link directly to an articulating boom structure, have also become important.
This August E-Crane International USA, which makes equilibrated-boom grab cranes, completed the mechanical assembly of a 1500B Series machine at (OVEC) Ohio Valley Electric Corporation’s Kyger Creek plant in Cheshire, OH.
For this project E-Crane® also acted as general contractor for the receiving hopper as well as the barge handling system, the first time it has provided total turnkey engineering of this type.
The crane is employed to discharge limestone from river barges which is needed for the flue gas desulphurisation (FGC) process at the plant. OVEC hired AEP (American Electric Power Company) to serve as overall project manager for the Kyger Creek FGD project. The next project is currently underway at Indiana-Kentucky Electric Corp.’s Clifty Creek plant in Madison, Indiana, where again E-Crane will provide a turnkey materials handling solution for a new FGD system. Installation of the handling equipment is scheduled for spring 2009.
The principal feature of the E-Crane® is its novel parallellogram, equilibrated boom structure which is said to make gravity work in favour rather than against the total lift concept.
This is said to reduce horsepower requirements and power consumption by up to 50%. Grab sway is also not a problem, since the grab is connected directly to the end of the boom structure.
Source: WorldCargo News (Issue December 2008)