GB2257051A

GB2257051A - Skimming apparatus

Info

Publication number: GB2257051A
Application number: GB9113708A
Authority: GB
Inventors: Ian Barry Mcdonald
Original assignee: WEATHERSTONES OFFSHORE Ltd
Current assignee: WEATHERSTONES OFFSHORE Ltd
Priority date: 1991-06-25
Filing date: 1991-06-25
Publication date: 1993-01-06
Anticipated expiration: 2011-06-25
Also published as: GB2257051B; GB9113708D0

Abstract

An apparatus for removing floating oil or algae from the surface of water, comprising a tank (10) supported by buoyancy means (12) below the water surface (18); an outlet (20) through which fluid is pumped from the tank; and one or more skimmers (24) disposed on the tank and forming respective floating weirs over which floating matter flows into the tank. Each skimmer comprises a vertical, open pipe (26) slidably extended through an aperture (28) in the roof of the tank, the upper end of the pipe carrying a flanged skirt which defines a convexly profiled surface (32a, 32b) and encloses plastics foam (34). The skirt causes the pipe to be lifted, when fluid is withdrawn through outlet (20), to a position wherein the weir is just below the surface of the floating matter. <IMAGE>

Description

DESCRIPTION SKIMMING APPARATUS The present invention is concerned with an apparatus for use in removing floating matter from the surface of water, such as oil and algae.

Many forms of apparatus have been developed for removing floating matter from the water but all suffer from disadvantages of inconvenience and/or inefficiency. It is an object of the present invention to provide an apparatus for this purpose which has advantages over existing equipment.

In accordance with the present invention, there is provided an apparatus for use in removing floating matter from the surface of a body of water, comprising; (a) a tank; (b) buoyancy means for supporting the tank such that, in use, it lies below the water surface; (c) outlet means on the tank for enabling fluid to be pumped from the tank; and (d) one or more skimmer devices disposed on the tank, the or each of which forms a respective weir which is caused, in use, to lie in or below the matter floating on the water surface and over which such floating matter on the water surface falls and enters the tank.

Preferably, the or each skimmer device comprises a vertical, open pipe which extends slidably through an aperture in the roof of the tank, the upper end of the pipe carrying a flotation means which causes the tube to adopt an operational position in which its upper end lies within or just below any floating matter, such as oil, on the water surface.

Advantageously, the flotation means on the pipe comprises a flanged skirt which is disposed at the upper end of the pipe and which defines an annular recess which can contain a mass of plastics foam.

In a preferred embodiment, the upper end of the flanged skirt defines a convexly profiled surface adjacent the open mouth of the pipe whereby, when fluid is drawn over the latter convex surface and into the pipe, as a result of fluid being extracted from the tank by way of such outlet means, a region of reduced pressure is generated above said convex surface whereby the skirt, and hence the pipe, is subjected to "lift" and is withdrawn from the tank aperture until such time as an equilibrium position is achieved in which the open mouth of the pipe lies within the floating matter, or just below same.

The convexly profiled surface can be smoothly curved or can be formed from a plurality of linear portions which are joined together to effectively form a convex profile.

The invention is described further hereinafter, by way of example only, with reference to the accompanying drawings, in which: Fig. 1 is a perspective view of one embodiment of an apparatus in accordance with the present invention for removing oil, or other floating matter, from the surface of water; and Fig. 2 is a sectional view through the apparatus of Fig. 1.

The illustrated apparatus comprises a cuboidal tank 10, preferably made of stainless steel, which forms a collection manifold and to which are attached two plastics buoyancy tanks 12a, 12b by way of lateral cantilevered booms 14a, 14b. The base of the tank 10 carries a quantity of ballast 16 in an amount sufficient to achieve neutral buoyancy for the apparatus as a whole whereby when the apparatus is in the water, the water surface 18 intersects the buoyancy tanks approximately at their mid-height.

Thus, the tank 10 is caused to be supported in a fully submerged position as shown in Fig. 2, at a substantially constant depth h below the water surface 18. Water can enter the tank 10 freely by way of flooding apertures 11.

Water can be selectively pumped out of the tank 10 by way of an outlet pipe 20 connected to a suitable pump (not shown). The pipe 20 may extend into the central region of the tank 10 as shown in Fig. 2, but may equally well terminate at or adjacent the wall of the tank.

Disposed in the horizontal roof 22 of the tank 10 are two identical skimmer devices 24 by which floating matter, such as oil, can be drawn into the tank 10.

Each skimmer device 24 comprises a tube or pipe 26 which is slidably received in a vertically extending guide sleeve 28 formed on the interior surface of the tank roof 22. A circumferential projection 30 on the tube 26 prevents it being withdrawn altogether from the sleeve 28. The end of the tube 26 remote from the projection 30 carries an outwardly extending, peripheral skirt 32 which defines an annular recess in which there is fixed a mass of plastics foam 34. The weight of the foam is chosen to be such that when not in operation, the tubes 24 adopt a fully retracted position relative to the tank 10 wherein the skirt 32 abuts the roof 22 of the tank, i.e. it lies well below the water surface.

The skirt 32 comprises three distinct sections, namely a first section 32a which extends perpendicularly relative to the tube (i.e. lies horizontally and parallel to the water surface 18, in operation) and forms a weir over which floating matter can drop into the tube 24; a second section 32b which extends downwardly relative to the horizontal section 32a (typically at an angle of about 50); and a third section 32a which extends parallel to the tube 26 and downwardly in relation to the section 32b.

In use, the apparatus is towed, e.g. using a chain 36 (Fig. 1), so as to lie in a region of water covered by a layer of floating matter, such as oil, which is to be removed. The pump is energised so as to withdraw fluid from the tank 10, thereby causing fluid flow into the tubes 24. As explained above, the upper ends of the tubes 24 are initially lying well below the surface 18 and therefore in water. The action of the pump thus causes water to enter the tubes 24.As a result of the effective convexly curved shape of the upper ends of the skirts defined by the sections 32a, 32b, there is generated a low pressure area above these sections which effectively causes lift on the skirts, and hence on the tubes 24, whereby the tubes rise out of th sleeves 28 until the upper ends of the skirts adopt an equilibrium position just below the surface 18 and therefore in or just below the floating layer which is to be removed. If the tubes were to ride any higher than this position so that they broke the surface 18, all "lift" would be lost and they would fall back below the surface again.

Thus, the open upper ends of the tubes lie in or just below the floating layer and form circular weirs over which the floating matter falls into the tubes, fluid being pumped out of the tank 10 at such a rate that the fluid level in the tubes 24 is maintained at a level below their upper ends, preferably at approximately the level indicated by the dotted lines x in Fig. 2. Oil or other floating matter is thereby caused to be drawn into the tank 10 from which it is withdrawn by the pump for collection in a suitable receptacle (not shown) and disposal elsewhere. An advantage of the present apparatus, therefore, is that the upper, inlet ends of the tubes 24 are automatically positioned and maintained at an ideal height below the surface 18 for selectively skimming floating matter, such as oil and algae, from the surface of the water without taking with it large and unnecessary quantities of water.

The upper ends of the tubes 24 can contain baffles 40 (see Fig. 1) which obstruct the entry of large pieces of flotsom without affecting the flow of fluid or small particles such as algae.

Although, the present embodiment uses two tubes and skirts 24, 32, the invention is not limited to any particular number and other embodiments may include any required number of these components, including just one.

Claims

1. An apparatus for use in removing floating matter from the surface of a body of water, comprising: (a) a tank; (b) buoyancy means for supporting the tank such that, in use, it lies below the water surface; (c) outlet means on the tank for enabling fluid to be pumped from the tank; and (d) one or more skimmer devices disposed on the tank, the or each of which forms a respective weir which is caused, in use, to lie in or below the matter floating on the water surface and over which such floating matter on the water surface falls and enters the tank.

2. An apparatus as claimed in claim 1, wherein the or each skimmer device comprises a vertical, open pipe which extends slidably through an aperture in the roof of the tank, the upper end of the pipe carrying a flotation means which causes the tube to adopt an operational position in which its upper end lies within or just below any floating matter, such as oil, on the water surface.

3. An apparatus as claimed in claim 2 wherein the flotation means on the pipe comprises a flanged skirt which is disposed at the upper end of the pipe and which defines an annular recess.

4. An apparatus as claimed in claim 3, wherein said annular recess of the flotation means contains a mass of plastics foam.

5. An apparatus as claimed in claim 3 or 4 wherein the upper end of the flanged skirt defines a convexly profiled surface adjacent the open mouth of the pipe whereby, when fluid is drawn over the latter convex surface and into the pipe, as a result of fluid being extracted from the tank by way of such outlet means, a region of reduced pressure is generated above said convex surface whereby the skirt, and hence the pipe, is subjected to "lift" and is withdrawn from the tank aperture until such time as an equilibrium position is achieved in which the open mouth of the pipe lies within the floating matter, or just below same.

6. An apparatus as claimed in claim 5 wherein the convexly profiled surface is smoothly curved or is formed from a plurality of linear portions which are joined together to effectively form a convex profile.

7. An apparatus for use in removing floating matter from the surface of a body of water, substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.