“Two in One” Traveling Shiploader/Unloader Combination

For the upgrading and renovation of an existing shiploading and unloading facility, primarily handling green and calcined petroleum coke, the ORBA Corporation of Houston, Texas, USA, was invited by AmClyde Engineering Products to prepare a detailed proposal for this project during the early spring of 1989.

The existing facility consisted of a traveling shiploader, a traveling hopper car and a reversible dock conveyor.  This conveyor feeds the shiploader via a trailer, or by running the conveyor in a reversed direction it will receive the inbound material from the hopper car.

The hopper car could be loaded by the ship’s own unloading gear or by means of a mobile crane situated on the dock.  As a result the dock became extremely congested and caused severe restrictions on the mobility of the shiploader as well as the hopper car.

GENERAL CONCEPTS

Obviously, the solution to this problem was to rid the dock of redundant equipment wherever possible, and it seemed that this could be achieved by using a single gantry with a dual function, loading as well as unloading.  Although this concept was realized some years ago by AmClyde, previously known as the American Hoist & Derrick Company [1] for a floating transshipment facility, it was clear that a different design was required due to the inherent limitation of the existing dock.  

The machine, as was visualized, should be able to load seagoing vessels up to 40,000 DWT and unload river barges.  In order to realize such a concept technically and economically, it was then decided between the ORBA and AmClyde engineers that the following design parameters should be set and adhered to:

• Use an unloader gantry of common design to minimize additional engineering;
• Existing dock conveyor to be utilized;
• Weights of added bulk material handling components such as conveyors, chutes etc. To be kept to a minimum;
• Unloading function not to be restricted n any way by the additional shiploading machinery introduced;
• The added shiploading ability not to be affected by the unloading machinery;
• Horizontal length of the elevating conveyor system to be kept as short as possible in order to obtain maximum travel on dock.

The equipment was sized to unload green petroleum coke at a rate of 500 t/h and 800 t/h as loading rate for the calcined petroleum coke.

The maximum reach of the grab bucket was set at 98 ft measured from the center line of the gantry track to accommodate two river barges moored side by side.  In order to load a 40,000 DWT vessel the loading spout or chute does not have to go beyond 93 ft from the center line of the track to reach the hatch opening.  It was also decided that the required boom conveyor should be of a shuttle design with its loading spout platform running on the same track as the grab bucket trolley.  This, of course, to provide for a balanced load distribution in the apron structure.

CONCEPTUAL DESIGN

Adherence to the aforementioned parameters resulted in a conceptual design, as illustrated in the figure below.  It consists basically of a standard type unloading gantry equipped with an elevating conveyor, fixed feed conveyor and a self propelled shuttle conveyor with telescopic chute at the discharge.