GB1435495A - Oil clean-up method - Google Patents

Abstract

1435495 Scavenging vessels; automatic buoyancy control BRITISH PETROLEUM CO Ltd 17 May 1973 [26 May 1972] 24936/72 Headings B7A and B7M [Also in Divisions B1 and F1] A floating oil slick is trapped by a floating boom 1 (Fig. 2, not shown) and the oil picked up by a device 6 comprising a plurality of flat discs 11, radially oriented along a pitch circle and supported by floats 15-19 so as to dip into the water, the discs being rotated about their respective axes to pick up the oil which is then removed therefrom by fixed scrapers (20) and pumped in a tanker or dracone 7. Boom 1 comprises elongated air-filled tube (10) and water-filled tube (9), presenting a figure of eight section, and further air tube (41) of much smaller diameter. Tube (41) is internally ribbed and may be inflated before or during the laying of the boom in the water. The boom is laid from a barge on which it is folded zig-zag and which carries an engine driving respective pumps, which inflate tubes (9, 10) once the boom is laid, and a cylinder to inflate tube (41, Fig. 6, not shown). The free end of the boom is attached to a drogue to assist laying the boom. Either one boom is laid at right angles to the path of the slick, or two booms are layed in a V formation and secured together. The boom(s) are laid downwind of the slick and the drogues brake the drift of the boom(s). Once the slick is trapped against the boom(s) the free ends are brought together to close the circle (Fig. 1). In device 6 the discs 11 are mounted on bearings 12 and made of polyvinyl chloride. The disc peripheries have teeth engaging a worm ring 13, which is rotated to turn the discs by pinion 14 engaging teeth on its inner periphery. A device with 78 discs of 10 foot diameter can pick up 100 tons of oil per hour. Float 15 may be open at the bottom and have an automatic system (Fig. 5, not shown) which pumps air in to maintain a constant immersion of discs 11 as the oil is removed from the surface. A float controlled bleed (40, 51) is normally open to maintain pneumatic valves (33, 38) closed, but as the device sinks the bleed touches the surface and closes, causing valve (38) to open valve (33) and deliver air to the float expelling the water.