Numéro : 1972 - Year : 1984
High speed oil skimming from the sea with VITECOPE system
B.VALIBOUSE, Ingénieur, Alsthom -Atlantique Neyrtec -Grenoble
A.BONAZZI, Ingénieur, Alsthom -Atlantique Neyrtec -Grenoble
Recovering oil from the surface of the sea by mechanical means poses a number of difficult problems. The main factors to be considered are the waves, which continually alter the level of the oil with respect to the boat, and the thickness of the oil layer. To deal with the wave problem, the vertical position of the scoop of the skimmer must be automatically controlled so that it follows the movement of the sea surface. The force needed to move the scoop and keep it at water surface level will be directly proportional to the mass of the scoop.
In all existing skim system, the mass of the scoop is increased by that of the entrained water because the scoop system serves not only to skim off the oil but also to move the oil-water mixture into the boat. The originality of the VITECOPE skim system described here is to separate these two functions and to derive as much benefit as possible from the ability of the system to keep itself at sea surface level. Both these desirable characteristics are found with an aquaplaning device that throws up a sheet of water -a phenomenon that a water skier produces when he slides sideways.
Another advantage of this type of skim system is that it enables only the top surface of the sea to be removed (without causing breaking bow waves) and that the oil-water mixture removed is thrown up against the hull where it can be collected by means of a guttering system. The thickness of the layer skimmed can be varied by adjusting the depth of immersion of the scoop.
After a brief summary of the literature on aquaplaning hull design, tests on three scoop designs are described and the installation of a skim system on a boat is discussed. This work was sponsored by the EEC and CNEXQ.