Disassembling System of Large Scaled Structure Considering Safety, Environmental Impact, and Economic Efficiency

Abstract

When a ship finished its lifetime, its hull is scrapped and recycled. Presently, the ships are scrapped mainly on the less-developed countries. The ship recycling in developing countries often comprises hazardous and environmentally damaging processes, and has developed into a serious problem from the viewpoint of realizing an international resource recycling society. It is predicted that over the next few years, disassembly of substandard ships that do not fulfill safety guidelines, such as single-hull tankers, will increase rapidly. Hence, economical, safe and environment-friendly ship disassembly processes are strongly desired. This paper proposes a planning method for the safe, economical, and environment-friendly ship disassembling process. The planning method derives an optimal disassembly process by considering safety, cost, and environmental impact. In order to develop this disassembling system, this paper addresses (1) a model of the scrapped ship, the facility, the field, and (2) a disassembling process models considering the hull, factory, and operations and (3) a planning method of disassembling process to achieve both of the safety and environmental cost. Based on the models and methods, a evaluation function that considers safety, disassembling cost, and environmental impact is proposed. An example of a disassembling process planning on an actual ship-hull structure is shown in this paper. A best planning result contains less unstable state of hull block, includes a lot of parallel tasks, and utilizes the best performances of equipments of the factory. The proposed system can provide not only safety information during disassembly to developing countries but also an economical disassembly equipment assignment plan to developed countries.