GB2026335A

GB2026335A - Oil skimmer

Info

Publication number: GB2026335A
Application number: GB7926296A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1978-07-27
Filing date: 1979-07-27
Publication date: 1980-02-06
Also published as: GB2026335B

Abstract

An oil collecting buoy 10 comprises a buoyant oil collecting chamber 11 adapted to float in sea water, the collecting chamber having an inlet(s) 22 adjacent its upper end and an outlet(s) 15 adjacent its lower end adapted to allow one way flow of sea water out of the collecting chamber, the buoyancy of the buoy being such that in use the inlet is normally positioned between the upper and lower limits of the sea water level determined by the sea swell to allow the inflow of oil and sea water into the collecting chamber when the sea water level rises above the inlet. As shown the inlet is surrounded by an adjustable skirt 24 and the inlet and the outlet are provided with valves 16, 23 respectively. <IMAGE>

Description

SPECIFICATION Liquid collector The present invention relates to a liquid collector which is particularly suitable for collecting oil from the surface of a heavier liquid than oil such as sea water.

There have been many proposals for disposing of oil from the surface of the sea by collecting the oil from the surface of the sea water or alternatively by dispersing and sinking the oil. For instance, British Patent Specification No. 1,475,985 discloses apparatus comprising a container having a skirt or wall which extends below the water surface and means above the water surface for directing a jet of fluid downwardly and across the bottom of the wall so that oil is carried by the jet into the container. While this arrangement is satisfactory in certain situations it requires complex apparatus and a source of power to generate the jet and therefore involves a relatively high initial cost and permanent running costs.

There is therefore still a need for apparatus for collecting oil from the surface of sea water which is relatively economic both to manufacture and operate.

In order to meet this need the present invention provides an oil collecting buoy comprising a buoyant oil collecting chamber adapted to float in sea water, the collecting chamber having an inlet adjacent its upper end and an outlet adjacent its lower end adapted to allow one way flow of sea water out of the collecting chamber, the buoyancy of the buoy being such that in use the inlet is normally positioned between the upper and lower limits of the sea water level determined by the sea swell to allow inflow of oil and sea water into the collecting chamber when the sea water level rises above the inlet.

In use, the buoy is placed in sea water having a film of lighter liquid such as an oil on its top surface, the buoyancy of the collecting chamber being such that the inlet is normally positioned above the surface of the sea water. The wave motion of the sea water will cause the level of the sea water and oil to rise relative to the collecting chamber so that the oil on the top surface of the sea water will wash into the collecting chamber through the inlet. The level of the sea water will then fall relative to the collecting chamber as the wave recedes and the hydrostatic pressure within the collecting chamber will force water from the bottom of the collecting chamber out through the one way outlet. As this operation is repeated the collecting chamber will fill with oil which can then be pumped out into a main collecting chamber or reservoir.

A preferred form of the present invention will now be described with reference to the accompanying drawings in which: Figure 1 is a vertical section through a liquid collecting buoy according to the present invention; Figure 2 is a section on the line A-A of a part of the buoy of Fig. 1; Figures 3 to 8 illustrate the cycle of operation of the buoy of Figs. 1 to 2 when subjected to a wave motion; Figure 9 is a graph illustrating the effect of the wave motion on the two component parts of the buoy of Figs. 1 and 2; Figure 10 is a section through a further embodiment of the buoy of Figs. 1 and 2; and Figure ii is a section through yet a further embodiment of the buoy of Figs. 1 and 2.

In Figs. 1 and 2 a liquid collecting buoy according to the present invention is indicated generally at 1 0. The buoy 10 comprises a cylindrical collecting chamber 11 which is provided with a buoyancy tank 1 2 surroundings its bottom end. The buoyancy tank 1 2 may be a continuous tank or may be divided into a plurality of separate compartments. The bottom of the chamber 11 is closed by a stepped bottom wall 1 3 having a cylindrical wall portion 1 4 formed with a plurality of liquid outlets 1 5 each of which is closed by a flap valve 16. The flap valves 1 6 are provided on the outside of the outlet 1 5 so as to allow one way flow of liquid out of the chamber 11.

A cylindrical flange 1 7 is welded to the bottom wall 1 3 and provided with an aperture 1 8 which acts as an anchor point for the collector 10.

The upper end of the collecting chamber 11 has a flared wall portion 19, an outwardly extending generally horizontal flange 20 and a vertically extending lip 21. The annular flange 20 is formed with a plurality of liquid inlets 22 each of which is provided with a flap valve 23 adapted to allow one way flow of liquid upwardly and into the flared portion 1 9 of the chamber 11.

A skirt 24 surrounds the flared upper end 1 9 of the chamber 11, the skirt 24 being mounted on a tubular sleeve 25 which is located as a clearance fit within the chamber 11. The upper end of the sleeve 25 is closed by a plate 26 and the skirt 24 is joined to the sleeve 25 by an annular extension 27 which overlies but is spaced from the flared portion 1 9 and flange 20 of the chamber 11.

The bottom end of the sleeve 25 is mounted on the wall of the chamber 1 by a plurality of leaf plates 28 which allow a limited amount of vertical movement of the sleeve 25 and thus of the skirt 24 relative to the chamber 11. The mounting of the leaf plates 28 on the wall of the chamber 11 is vertically adjustable to enable the gap 'x' between the level of the inlets 22 and the bottom edge 29 of the skirt 24 to be adjusted. The sleeve 25 is formed with a plurality of axially extending slots 30 for the inflow of liquid through the sleeve 25 and also with a vertically extending oil sensor 31. The skirt 24 is also provided with a buoyancy tank 32 which may comprise a single continuous buoyancy chamber or which may be divided into a plurality of separate chambers.

Figs. 3 to 8 show the sequence of movements of the buoy 10 when it is floating in sea water and subjected to a wave motion.

When the water is stationary as shown in Fig.

3 the buoyancy of the buoy and the skirt is so designed that the upper surface of the oil which is resting on the sea water is above the bottom edge 29 of the skirt of the collector and below the inlets 22. As a wave approaches the buoy, as shown in Fig. 4, hydrostatic pressure outside the collector causes the water outlet flaps in the base to close allowing oil and water to enter through the inlets 22 as the water level rises on one side of the collector. During this phase of the cycle and up to the crest of the wave there is an intake of oil and water through the inlets 22 and into the chamber 11.

As the wave passes the buoy, as shown in Fig. 6, the hydrostatic pressure inside the buoy causes the water outlet flaps 1 6 to open allowing water from the bottom of the chamber 11 to escape. At the same time, the flaps 23 at the upper end of the chamber will close so that oily water is trapped within the chamber 11.

At the trough of the wave movement, as shown in Fig. 7 water will continue to be expelled from the outlets at the bottom of the chamber and the oil and water level outside the chamber will drop below the skirt 24. The cycle will then commence again as the next succeeding wave approaches the buoy, as shown in Fig. 8.

As the chamber 11 of the buoy 10 fills with oil the depth of oil in the chamber is sensed by the sensor 31 which will signal the level of oil and if necessary initiate the transfer of oil from the chamber 11 to a main reservoir such as a tanker.

The relative movement of the water and oil surface, the skirt and the chamber 11 are shown graphically in Fig. 9. As can be seen, the inertia of the main chamber 11 is greater than the inertia of the skirt and consequently the skirt lags relative to the surface of the wave and the movement of the collecting chamber lags the movement of the skirt thereby creating a difference between the vertical oscillation of the collector and the water and oil surface to create an intermittent flow of oil from the upper surface of the water into the upper end of the chamber 11.

The dimension 'x' which is the gap between the inlet 22 and the bottom edge 29 of the skirt 24 is adjusted so that it is less than the wave amplitude. The mounting of the sleeve 25 and the skirt 24 on the chamber 1 may be such that it can be manually adjusted or alternatively motor driven. If the mounting of the sleeve on the chamber 11 is motor adjustable the motor drive may be arranged so that it is controlled by the water wave motion, for instance the greater the wave motion the greater the skirt depth 'x'.

In an alternative embodiment of the present invention the skirt and the chamber 11 may be independent of each other so that they are free and floating. Due to the different masses of the chamber 11 and the skirt they will oscillate vertically out of phase. It is also envisaged that the chamber and the skirt may be independent but controlled so as to oscillate relative to one another automatically.

In yet a further embodiment of the present invention it is envisaged that the buoy may be automatically oscillated in phase with the water surface so as to provide a constant weir height thereby removing the necessity for a skirt.

In an alternative embodiment of the collector 10 which is indicated generally at 40 in Fig. 10, a skirt 41 is provided with a buoyancy tank 42 on the inner surface of the skirt 41 and the adjacent surfaces of the skirt 41 and the chamber 43 are arranged to converge towards the liquid inlet 44.

In yet a further embodiment of the present invention which is indicated generally at 50 in Fig. 11, a skirt 51 is mounted in the upper end of a collecting chamber 52 by a plurality of resilient leaf springs 53 which allow vertical freedom of movement of the skirt 51 relative to the chamber 52 but which provide horizontal restraint for the skirt.

The buoy of the present invention may be free floating, anchored or part of the construction of a ships hull. Alternatively it may form part of a fixed construction such as a dock wall.

The buoyancy tanks may be filled with a material lighter than water or air filled and the air filling may be controlled to provide the phase characteristics desired in relation to the wave motion.

In the buoy 10, there is a small gap between the sleeve 25 and the wall of the chamber 11. This gap may be divided into a plurality of segments by a flexible membrane if the vertical movement of the skirt is independent of the chamber 11 or alternatively by steel panels if the skirt and the chamber are rigidly attached to one another.

If the overall diameter of the buoy is intended to be very substantial of the order of several hundred metres then it is envisaged that the skirt may be split into a plurality of independently moveable segments.

In all of the embodiments of the invention described and illustrated herein a skirt is provided around the upper part of the collecting chamber and a plurality of restricted inlets are provided to allow flow of liquid into the collecting chamber when the level of liquid out side the chamber rises. The provision of a skirt, while preferable since it improves the performance of the collector is not essential.

The collecting chamber may be provided with an open upper end and provided the buoyancy of the collector is correctly gauged, liquid will wash over the upper end of the collector and into the collecting chamber as the liquid outside the buoy rises and falls.

It will also be appreciated that the inlet flap valves are advantageous but not essential as the buoy will operate without any valves on the inlet aperture.

Claims

1. An oil collecting buoy comprising a buoyant oil collecting chamber adapted to float in sea water, the collecting chamber having an inlet adjacent its upper end and an outlet ajdacent its lower end adapted to allow one way flow of sea water out of the collecting chamber, the buoyancy of the buoy being such that in use the inlet is normally positioned between the upper and lower limits of the sea water level determined by the sea swell to allow the inflow of oil and sea water into the collecting chamber when the sea water level rises above the inlet.

2. An oil collecting buoy as claimed in claim 1, wherein the collecting chamber is open topped, whereby the open top constitutes the said inlet for oil and sea water.

3. An oil collecting buoy as claimed in claim 1, wherein the upper end of the collecting chamber is surrounded by a skirt which is spaced from the collecting chamber, the skirt having a bottom edge positioned below the inlet.

4. An oil collecting buoy as claimed in claim 3, wherein the skirt is vertically freely movable relative to the collecting chamber.

5. An oil collecting buoy as claimed in claim 4, wherein the buoyancy of the skirt is different to the buoyancy of the collecting chamber and such as to accentuate in use the relative movements between the skirt and the collecting chamber in response to the sea swell.

6. An oil collecting buoy as claimed in claim 3, wherein the skirt is connected to the collecting chamber.

7. An oil collecting buoy as claimed in claim 6, wherein the vertical portion of the skirt is adjustable relative to the collecting chamber.

8. An oil collecting buoy as claimed in claim 6, wherein the skirt is freely movable vertically relative to the collecting chamber within a predetermined range of movement.

9. An oil collecting buoy as claimed in any preceding claim wherein the collecting chamber is provided with a plurality of inlets and a plurality of outlets.

10. An oil collecting buoy as claimed in any of claims 3 to 9, wherein the collecting chamber comprises a cylindrical wall having a flared upper end terminating in a generally horizontal outwardly extending peripheral flange formed with a plurality of inlets each having a one way valve allowing upward flow of liquid through the inlet and a closed bottom end and a plurality of outlets adjacent the bottom end each having a valve allowing outward flow of liquid from the collecting chamber, and wherein the skirt is telescopi cally mounted relative to the collecting chamber.

11. An oil collecting buoy as claimed in any of claims 6 to 8, wherein the skirt is divided into a plurality of independently removable segments.

1 2. An oil collecting buoy as claimed in claim 10 or claim 11 wherein the skirt is provided with one or more integral buoyancy tanks.

1 3. An oil collecting buoy as claimed in any of claims 10 to 1 2 wherein the collecting chamber is provided with one or more integral buoyancy tanks.

1 4. An oil collecting buoy as claimed in any of claims 10 to 13, wherein the skirt is connected to a sleeve which is mounted within the connecting chamber.

1 5. An oil collecting buoy as claimed in any of claims 10 to 1 3 wherein the sleeve is connected to a diaphragm which is mounted on the collecting chamber.

1 6. An oil collecting buoy substantially as described herein with reference to Figs. 1 to 9 or Fig. 10 of the accompanying drawings.