Offshore Bulk Receiving Station-A Systems Approach Concept

Abstract

Introductory This paper describes a new approach to the transportation, unloading and receiving of bulk, sized, dry, bulk raw materials. The concept described in the paper was developed in the course of long range master planning studies for an industrial complex to be located on the West Coast of the United States. The program requirements which led to the development of the concept described in this paper following:Sized are and other similar raw materials will be required to be received from abroad by ocean bulk carrier at the rate of 20 million tons per annum.Ocean freight costs dictate that ships of 150,000 DWT class with a 60 foot draft must be considered as the minimum economic size to serve such an operation.No existing or planned harbor development, to receive ships of this class, will serve any site in the general area where market studies dictate that the industrial complex be located. An area was studied as a prospective site for the industrial complex, where 80 foot water depths exist in an unsheltered ocean area about one mile off shore. To receive the sized ore at the rate of 10,000 tons per hour, as well as the other raw materials with similar handling characteristics, a systems approach indicated that the following should be provided.Self-unloading bulk carriers.Offshore bulk receiving station.Conveyor tube and belt conveyor to shore stockpiles. An artist's concept of the operation is shown In Figure I. A self-unloading bulk carrier is moored by the bow, discharging cargo to the offshore bulk receiving station while "feather vanes" by valid and current to present the aspect of minimum resistance to such forces. This provides the most favorable mooring and unloading situation. Self-Unloading Bulk Carriers A dedicated fleet of self-unloading bulk ore carriers, 150,000 DWT cargo capacity is shown (Figs. 2 and 3), discharging through a system of:Sloping hopper sides.Feeder gates.Reclaim belt conveyors under cargo holds, carrying ore aft and near the aft ends, Inclining upward to feed cross chutes or cross conveyors to the ship centerline.An elevating belt conveyor on the ship centerline, 10,000 ton per hour capacity, carrying ore forward, set on the tank top for part of Its length, inclining upward for part of Its length as necessary to elevate the are to a transfer point.Penetration through the cargo space by the inclined belt conveyor would be through a conveyor trunk, sealed from the cargo holds, with a pitched top to shed cargo during loading and unloading.Conveyor boom supporting and housing a 10,000 ton per hour capacity boom belt conveyor. When discharging cargo, the conveyor boom would be moved from the stowed position, extended over the bow and rested, with boom falls and slewing tackle slacked off, on the edge of the hopper of the offshore bulk receiving station. The conveyor boom operating machinery would have the capability of retracting the conveyor boom into the elevating conveyor housing for stowing under voyage conditions. Water-tight doors would close all above deck openings Into the elevating conveyor housing.