Deep-sea Mining, Ore Transport Hose Buoyancy Spherical Shell Design

The 21st century is the century of developing and exploiting Deep Ocean. The international ocean bottom (approximately 21.2 billion square kilometres) , which occupies the 49 percent of the earth surface, contains rich resources such as strategic metals, energy sources and biological resources. With the resource scarcity on land and the enhancement of the knowledge about the Ocean, the international deep ocean will become the important strategic target gradually. In March 1999, China obtained the ocean mining "contract areas" of 75,000 square kilometres. In 2001, our country completed the lake test of deep sea mining system in the Fuxian Lake, and in November 2004, completed the technical design of the 1,000 m sea test system.This paper mainly does research about the buoyancy material in the deep sea mining transporting system. It is found that buoyancy material used in deep sea is still in the laboratory stage. And in 2006, 863 thematic topics plan set up a great depth buoyancy material topic. By comparison, the paper proposes a hollow spherical shell, which is made by low-density, high-strength aluminium alloy and titanium alloy, to provide buoyancy for deep sea transporting system.Based on the actual situation of buoyancy spherical shell, the relation of its deformation and force is derivated. And spherical shell parameters are calculated according to the requirements of great depth buoyancy material. When the buoyancy spherical shell works in deep sea, its failure mode is buckling. The research is divided into two parts: no inflatable and inflatable buoyancy spherical shell. As for no inflatable buoyancy spherical shell, by simplifying shell and comparing various finite element parameters, a validated model was established. Using ANSYS buckling analysis function, the buoyancy spherical shells with different thickness-radius ratio are studied. And the density and the ultimate depth meeting requirements are obtained. In buckling analysis process, such factors as initial defects, material are considered. In order to increase ultimate depth of the buoyancy shell, in the final part of this paper, inflatable buoyancy spherical shell is analysed. By comparison, low-density helium is chosen as high-pressure gas in the shell, and is inflated in the shell using helium compressor. The inflatable buoyancy spherical shell is analysed using the same method as no inflatable buoyancy spherical shell. And the density and the ultimate depth meeting requirements are obtained. By comparing results of spherical shell and specifications of 863 great depth buoyancy material, some valuable conclusions are drawn.