Robert Allan Ltd., Canada’s most senior consulting naval architecture firm, was recently engaged to design a system for transporting wood chips by barge to a transhipment zone and then loading them into Handymax-sized vessels for export.
Robert Allan Ltd. contacted CWA for assistance with developing a material handling system for transloading the chips from the barges to the bulk carriers. Initially, CWA was asked to design a 1,500 t/h system utilizing hoppers, conveyors, and front-end loaders.
A number of factors complicated the development of the conventional material handling system:
- Access for front-end loaders would be extremely tight on a barge with a system of conveyors and hoppers.
- There were operational and safety concerns with front-end loaders working in open-sea conditions.
- Larger-than-envisioned barge dimensions would be required to accommodate the material handling system and front-end loader access.
Through in-depth discussions with Robert Allan Ltd., CWA learned that the ultimate objective was to load a Handymax-sized vessel (35,000 tonnes of woodchips) within 72 hours and that the constraints included the availability of only three wood chip barges at a capacity of 6,000 tonnes each. This deeper understanding of the client’s needs enabled CWA to develop a material handling system more suited to their requirements.
CWA completed preliminary design drawings and a cost estimate according to the original specifications, but also presented a second option: using hydraulic equilibrium cranes (E-Cranes) to transload the wood chips. The project had initially rejected cable-operated grab cranes because of concerns related to barge damage, but E-Cranes, which are more controllable, had not been considered.
CWA performed a time and motion study comparing the two options within the given constraints. The results showed that the E-crane system could load a Handymax-sized vessel three hours faster than a system of conveyors and front-end loaders. As the crane system also offered significant capital and operating cost advantages in addition to providing a faster loading time, the client chose to move forward with it.