BACKGROUND

Built for world-wide ocean trade by Canada Steamship Lines (CSL), the CSL Innovator is a Panamax-class self-unloading vessel. (Panamax-class refers to a ship that has a dead weight of between 60,000 and 70,000 tons and is capable of traversing the Panama Canal.)

THE PROBLEM

CSL's new vessel had to be capable of transporting and discharging a wide range of materials. Typical free-flowing products include grain, iron ore pellets, and aggregates. Cohesive products include wet ores, concentrates, and cohesive coals. Fine, dry, dusty products include alumina and possibly cement. Products that cake include salt, potash, and sugar. Many products are single sized, but others, like gypsum, can contain large, slabby lumps.

The configuration of holds and hoppers had to maximize the useable volume in a Panamax-class vessel. In order to maximize useable volume, it was necessary to use a three-belt withdrawal configuration rather than a conventional two-belt system. Also, the hopper slopes had to be kept as shallow as possible, yet be capable of handling cohesive/adhesive cargos.

The vessel was designated with 240 gates. Gate configurations had to take minimal headroom. In addition, each gate had to provide good flow control for a wide range of free-flowing and non free-flowing cargos. Finally, it had to be cost effective, easy to construct, and mechanically robust.

THE SOLUTION

Personnel in Jenike & Johanson's office in Toronto, Canada, worked closely with CSL for a two-year period, designing and redesigning hopper and gate configurations. Flow property results obtained for a very cohesive iron ore concentrate were used as the design basis material. Jenike & Johanson considered many gate design concepts, constructed working models and performed flow pattern tests. Eventually, we developed a new gate of the "basket" or "swing" gate type in conjunction with Consilium CMH Marine AB (Fig. 1C).

THE RESULT

The new ship, aptly named the CSL Innovator, has been in continuous service since September 1988. To date, the performance of the new hold configuration and gate design has been exceptionally good and has far exceeded industry expectations. Raymond Johnston, CSL's V.P. Customer Services and Transportation, states, "As a result of the significant amount of research and development time and money that went into the CSL Innovator, we now have the most technologically advanced self-unloading vessel in the world. With the vessel's unique capability to handle a wide range of difficult cargos, satisfy environmental requirements with respect to dust and noise pollution, and offer superior discharge flexibility with the articulated boom, this is one R&D project that has certainly paid off."

Email This Article