GB1276570A - Method and apparatus for recovering a substance floating as a sheet on the surface of a liquid mass - Google Patents

Abstract

1276570 Separation of floating impurities BERTIN & CIE and ENTREPRISE DE RECHERCHES ET D'ACTIVITES PETROLIERES-ELF 23 Dec 1969 [23 Dec 1968 28 Nov 1969] 62535/69 Heading B2P In a method of recovering a substance 2, Fig. 2 spread as a sheet covering a large area and floating on the surface 1a of a mass of liquid 1, the liquid is subjected, in the vicinity of its surface, to rotation about a vertical axis so as to bring about a downward pull on whorls of liquid and the formation, at the surface of the liquid, of an upwardly and outwardly flared open cavity 3 into which the substance originating from the sheet flows and accumulates, acquiring a thickness H greater than the thickness h of the sheet, and the accumulated substance is extracted from the cavity 3, the amount extracted being automatically replaced as it is extracted by further substance emanating from the sheet. The substance 2 may be a liquid, e.g. a hydrocarbon such as oil or crude petroleum, or a solid finely dispersed over the surface of the liquid. In Fig. 3, a swirl-inducing screw propeller 6 is dipped into the liquid mass 1 and is rotated by a motor 8 carried by a platform 5 supported by floats 12, preferably of curved shape Fig. 4 (not shown) and connected to the bottom 14 by an anchoring device 13. The screw is surrounded by a fairing 9 which limits the volume of liquid set in motion. The fairing is connected to the platform by rods 11 and has an inwardly bent, upper edge 9b and an open lower end. The substance 2 to be recovered is extracted from the cavity 3 by means of a pipe 15a and a pump 16 which delivers it via a pipe 15 to a floating tank 17. In modifications, the fairing may have: (a) an outwardly bent lower edge 9a; (b) a closed bottom, in which case the propeller has flat blades; (c) a bottom with one or more openings. In a further modification, Fig. 9, the swirl-inducing means is constituted by a downwardly slanted nozzle 20 which opens within the fairing 9 for tangential injection of swirlinducing fluid which may be of the same nature as that of the liquid mass. In a modification of the swirl-inducing arrangement. Fig. 11, a nozzle 27a cooperates with a fairing 27 to form an aspirator device 27, the fairing being fitted internally with inclined or screw-shaped vanes 27c. In a modification, Fig. 10, the substance 2 is extracted from within the cavity 3 by means of a net 24 placed below the fairing 9 and raised when necessary by means of a cable 25 connected to the floating platform. In a modification of the Fig. 3 arrangement, Fig. 12 (not shown), the motor driving the screw propeller is placed beneath it in a fluid tight chamber inside the fairing 9 and the pipe for extracting the substance from the cavity extends through the bottom of the fairing through the hollow shaft of the propeller. In a modification of this last arrangement, Fig. 13 (not shown), the hollow propeller shaft also drives a centrifugal extracting pump and extends beyond the propeller to open in the cavity and feed the substance to be extracted to the pumps which delivers it to the extracting pipe. A number of other swirl-inducing devices and extracting arrangements are described. As shown in Fig. 14, the platform is replaced by a boat 36 of the Catamaran type. The motor 8 driving the propeller 6 is supported on a gantry 38 mounted on the hulls 36a 36b. The fairing 9 is connected to the hulls by fasteners 39. A flat-bladed wheel 37 is rotatably mounted between the two hulls. As the boat proceeds in the direction of the arrow F the wheel 37 rotates counterclockwise and causes the sheet 2 of substance to accumulate in the space defined by the wheel, the hulls 36a, 36b and the structure 36c. When the amount of substance 2 accumulated in this way is sufficiently large the boat is stopped and the motor 8 started in order to deliver the substance to the tank 17. In a modification, Fig. 16 (not shown), a number of propellers surrounded by their respective fairing are mounted on a floatable support drawn along by a boat this arrangement having the advantage that it operates without stopping the boat.