GB2033773A

GB2033773A - Apparatus for collecting a surface layer of liquid

Info

Publication number: GB2033773A
Application number: GB7844253A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1978-11-13
Filing date: 1978-11-13
Publication date: 1980-05-29
Also published as: GB2033773B

Abstract

Apparatus for collecting a surface layer on a body of liquid, e.g. a layer of oil on water, comprises a member (1) defining a central passage (2) which is upwardly open and is arranged in use with the opening at the level of the interface between the surface layer of liquid and the underlying layer, and a member (3) which defines an annular passage with member (1) provided with vanes (8) which form the rotor of an axial pump when the members (1, 3) are rotated about the axis of the passage (2). This rotation causes the layer of liquid underlying the surface layer to be drawn towards the apparatus and downwardly around the passage (2) to draw the surface layer of liquid into the passage (2). Pump 15 conveys liquid from passage (2) to a reservoir. Members (1, 3) may be rotated by pneumatic turbine (9). <IMAGE>

Description

SPECIFICATION Improvements in and relating to the collection of a surface layer of liquid The present invention relates to the collection of a surface layer on a body of liquid and is particularly but not exclusively applicable to the collection of a layer of oil on the surface of a body of water. There are at present essentially two methods of removing an oil layer from the surface of a body of water and these are chemically, by dispersing the oil using chemicals, and mechanically by collecting the surface layer of oil. At present the most effective method is by the use of chemicals but it is thought that the chemicals do as much, if not more, damage ecologically than does the oil layer itself. It is consequently advantageous to collect the oil mechanically and in such a condition that it can be re-used, particularly with the increasing price of oil.

According to one aspect of the present invention there is provided an apparatus for collecting the surface layer of a body of liquid, the apparatus comprising a body defining a passage having one end open, the other end being adapted for connection to pump means for removing liquid in the passage, the body being adapted in use to be positioned in a body of liquid with the open end of the passage level with the interface between the layer to be collected and the underlying layers of liquid, and drive means for causing the surface layers of liquid to flow towards the open end of the passage.

The body preferably includes a generally planar flange surrounding the open end of the passage, the flange being in use arranged to lie in the plane of the interface so that the layer to be collected flows over the flange into the passage.

The drive means for causing the surface layers of the liquid to flow towards the open end of the passage may comprise means defining an annular passage surrounding the one passage and pump means causing liquid to flow down the annular passage. The apparatus is arranged so that the liquid flowing down the annular passage is constituted by the layer of liquid underlying the surface layer of liquid to be collected, which is thereby drawn towards the apparatus.

The drive means may create a whirling flow of liquid down the annular passage, the central passage having the general shape of the cavity created by a vortex in a body of liquid.

The body of the apparatus may comprise a first generally cylindrical member having a radially extending flange at one end and defining the central passage and a second correspondingly shaped member surrounding the first member and defining an annular passage therebetween. The other end of the first member is provided with or connected to a pump for removing liquid flowing into the central passage. The annular passage between the two members is open at both ends and provided with a pump for causing liquid to flow therealong.

Preferably the apparatus is arranged to have a specific gravity in use such that it will float with the flange of the first member level with the interface between the surface layer of liquid to be collected and the underlying layers of liquid.

According to another aspect of the present invention there is provided a method of collecting the surface layer of a body of liquid comprising creating a vortex in the liquid and collecting and removing the surface layer of the liquid forming the said vortex.

According to a further aspect of the present invention there is provided a method of collecting the surface layer of a body of liquid comprising creating a vertically extending cavity in the liquid, collecting and removing the surface layer of the liquid defining the cavity and causing the liquid underlying the surface layer to flow towards the cavity to draw the surface layer of liquid into the cavity.

Further features of the present invention will become apparent from the following description of an embodiment thereof, given by way of example only, with reference to the accompanying drawings, in which: Figure 1 is a diagrammatic axial section through an embodiment of apparatus according to the present invention; and Figure 2 is a section on the line Il-Il of Fig.

1.

The apparatus shown in the drawings comprises a first member 1 defining a passage 2 therethrough, the member 1 having a cylindrical part 1 a provided with a generally radially extending flange 1 b at one end. Surrounding and coaxial with the member 1 is a second member 3 defining with the member 1 an annular passage 4. The member 3 comprises a generally cylindrical part 3a and a radially extending flange 3b underlying the flange 1 b.

The flanges 1 b, 3b merge with the parts 1 a, 3a by radiused portions so that the members 1, 3 generally have the shape of a vortex created in a body of liquid.

In use, the apparatus is placed with the flange 1 b in the plane of the interface between the surface layer 5 of liquid to be collected, e.g. oil, and the underlying layers 6 of liquid, e.g. water, so that the oil flows over the flange 1 b and into the passage 2, from which it is removed, and water flows through the annular passage 4 and exits through the open lower end 7 thereof.

Oil and water is caused to flow to and through the apparatus by providing means for driving water through the annular passage 4 to cause a positive flow of water towards the apparatus and therefore a positive flow of the surface layer 5 to be collected. The lower end of the passage 2 is connected to or, as shown, provided with pump means for removing liquid therefrom.

As shown impellor vanes 8 are provided between the members 1, 3 in the annular passage 4 which are arranged to constitute an axial pump between the parts 1 a, 3a and to constitute liquid collecting vanes between the flanges 1 b, 3b. The vanes 8 are fixed to the members 1 and 3 which are rotated about the axis of passage 2. As shown the members 1, 3 are rotated by an air driven impulse turbine 9 whose blades 10 are fixed to or made integral with the member 3. It will be appreciated that the members 1, 3 may be driven in rotation by other means which may be pneumatic, hydraulic or electric.

Vanes 11 may also be provided on the surface of flange 1 b to assist flow of oil into the passage 2. Oil is removed from the lower end of the passage along a pipe 12 by a pump connected to that passage or, as shown, by a pump provided at the lower end of passage 2. As shown part 1 a of member 1 is extended by a cylindrical member 13 which is connected to member 1 by a fluid tight connection permitting relative angular rotation between the parts 1 and 13. At the lower end of member 13 there is a radial impellor pump 14. As shown the blades 1 5 of the pump 14 are fixed to or formed integrally with member 13 for rotation therewith and the casing 16 is connected to member 13 by a fluid tight coupling permitting relative rotation therebetween.The member 13 and therefore the blades 15 are rotated by a motor 17 which may, as shown, be an air driven impulse turbine the blades 18 of which are fixed to or formed integrally with member 13.

To prevent rotation of the casings of the motors 9 and 17 and of the pump 14, they may be connected by stays 19.

In operation of the above described apparatus, the members 1, 3 are rotated by motor 9 in the direction of arrow 20 in Fig. 2. This causes the underlying layers 6 of water to flow down the annular passage 4 and thereby draws the surface layer 5 of oil into the apparatus. This surface layer flows over the surface of flange 1 b and into passage 2 and is driven therefrom the pump 14 along outlet pipe 12. Pipe 12 is connected to means for separating the oil from the water which is inevitably also taken into the apparatus, such separating means being for example a settling tank or centrifuge. The separating means may be provided on a vessel which also provides the pneumatic power for the motor 9 and 17.

The apparatus is advantageously designed so that in use with a preset level of liquid in passage 2 the apparatus will float with flange 1 b at the interface between the surface layer to be collected and the underlying layers. The apparatus may then be supported from the vessel by stays 21 for example connected to the casing of the motor 9 so as to permit vertical movement of the apparatus but to restrain the apparatus against horizontal movement. The level of liquid in passage 2 can be maintained constant by controlling the motors 9 and 17 to increase or reduce the flow of liquid into and from the passage 2. To facilitate control a level detector may be provided at the required level to provide a signal in the vessel indicating when the level is too high or too low.Additional buoyancy control means (not shown) may also be provided to assist in controlling the level of the apparatus in the liquid and for use when starting and stopping the apparatus.

The members 1, 3, 13 and 15 may be moulded or otherwise made of a suitable oil resistant plastics material or fibre glass. The casings of the pump 14 and turbines 9 and 17 may be made of similar materials or of metal. The members 1, 3 may, for example, be made of neoprene or a synthetic rubber so that the flanges 1 b, 3b are flexible.

In a preferred embodiment the flanges 1 b, 3b have an outside diameter of 366 cms and the passage 2 has a diameter of 61 cms.

There is thus provided an apparatus for collecting the surface layer of a body of liquid which, in its preferred form, produces an artificial vortex in the body of liquid and separates the surface layer in the vortex from the underlying layers of the liquid. More generally, the apparatus creates a cavity in the body of liquid and draws the surface layer of the liquid into the cavity by driving the underlying layers of the liquid down the sides of the cavity.

Claims

1. Apparatus for collecting the surface layer of a body of liquid, the apparatus comprising a body defining a first passage having one end open, the other end being connected to pump means for removing liquid from the passage, the body being adapted in use to be positioned in a body of liquid with the open end of the passage level with the interface between the layer to be collected and the underlying layer of liquid, and drive means for causing the surface layer of liquid to flow towards the open end of the passage.

2. Apparatus as claimed in claim 1, wherein the drive means is adapted to cause the layer of liquid underlying the surface layer to flow towards the body so as to draw the surface layer of liquid towards the body and to cause it to flow into the open end of the passage.

3. Apparatus as claimed in claim 2, wherein the drive means are adapted to cause the layer of liquid underlying the surface layer to flow towards the body and then downwardly around the externally of the passage.

4. Apparatus as claimed in any one of the preceding claims, wherein the drive means include means defining a second annular passage surrounding the first passage, the annular passage having an inlet opening in an upper part which is, in use, at a level below the said interface, and having an outlet opening in a lower part, and pump means for causing liquid to flow downwardly through the annular passage.

5. Apparatus as claimed in any one of the preceding claims, wherein the body comprises a first generally planar flange surrounding and connected to the open end of the first passage, the flange being arranged so that in use it will lie in the plane of said interface so that the surface layer to be collected will flow over the flange and into the passage.

6. Apparatus as claimed in claim 5, wherein the first flange is provided with upwardly projecting vanes of arcuate shape for guiding the surface layer of liquid into the first passage.

7. Apparatus as claimed in claim 6, wherein the first flange is provided with downwardly projecting vanes which are arcuate in shape and correspond to the upwardly projecting vanes, the downwardly projecting vanes extending into an annular passage surrounding the first passage to form the rotor of an axial pump constituting the drive means, means being provided for rotating the body about the axis of the first passage.

8. Apparatus as claimed in claim 7, wherein the body comprises a second flange underlying the first flange and connected to the upper end of the annular passage to guide liquid into the annular passage, the downwardly projecting vanes being connected to the second flange, and the flanges together forming a passage for liquid flowing to the annular passage.

9. Apparatus as claimed in claim 8, wherein the first flange and the first passage and the second flange and the annular passage each have substantially the shape of a vortex created in liquid.

10. Apparatus as claimed in any one of claims 7 to 9, wherein the pump means connected to the other end of the passage comprises a radial pump comprising a rotor rotatable about the axis of the first passage and in the opposite direction to the direction of rotation of the body.

11. Apparatus as claimed in claim 10, wherein the rotor of the pump is fast with a member defining a passage in extension of the first passage and which is rotatable relative thereto.

12. Apparatus as claimed in any one of the preceding claims, whrein the stators of the drive means and pump means are connected together by a framework of the apparatus.

13. Apparatus as claimed in any one of the preceding claims, wherein the apparatus is adapted so that it will float at a predetermined position relative to the surface of the liquid with a predetermined level of liquid in the first passage, and means are provided for detecting the level of liquid in the first passage for use in controlling the pump means and/or the drive means.

14. Apparatus as claimed in any one of the preceding claims, including adjustable buoyancy means for use in adjusting the position of the apparatus relative to the surface of the liquid.

15. A method of collecting the surface layer of a body of liquid comprising defining a vertically extending cavity in the body of liquid which cavity opens upwardly in the plane of the interface between the surface layer and the underlying layer, causing the liquid to flow towards the cavity to cause the surface layer to flow into the cavity, and removing liquid from the cavity.

16. A method of collecting the surface layer of a body of liquid comprising defining a vertically extending cavity in the body of liquid, which cavity opens upwardly in the plane of the interface between the surface layer and the underlying layer of liquid, causing the liquid underlying the surface layer to flow towards the cavity and then downwardly around the cavity to draw the surface layer of liquid into the cavity, and removing liquid from the cavity.

17. A method as claimed in claim 16, wherein the underlying layer of liquid is caused to flow inwardly towards the cavity by creating a vortex therein.

18. Apparatus for collecting the surface layer of a body of liquid substantially as herein described with reference to the accompanying drawings.

19. A method of collecting the surface layer of a body of liquid substantially as herein described with reference to the accompanying drawings.