GB2088783A

GB2088783A - Floating booms

Info

Publication number: GB2088783A
Application number: GB8037461A
Authority: GB
Original assignee: UK Secretary of State for Defence
Current assignee: UK Secretary of State for Defence
Priority date: 1980-11-21
Filing date: 1980-11-21
Publication date: 1982-06-16
Also published as: GB2088783B

Abstract

A system for collecting oil from the surface of water comprises a perforated hose 15 connected to a source of pressurised gas and connected near to the lower edge of a flexible submerged skirt 14 which serves to guide air bubbles 13 issuing from the perforations to the surface of the water. The skirt 14 is dependent from a buoyancy tube 4 attached to its for upper edge and is maintained submerged by providing a weighting chain or water-filled hose within a pocket 6 provided along the lower edge of the skirt. An upwardly directed fence 9 may be attached to the buoyancy tube 4 to prevent oil from being swept through the barrier of bubbles 13 and over the buoyancy tube by wave motion. Two perforated hoses 15 may be provided one on either side of the skirt 14, such that the bubbles may be produced on the upstream side of the skirt 14 in response to changes in the direction of tidal current 17. <IMAGE>

Description

SPECIFICATION Improvements in or relating to oil pollution control The invention relates to the control of oil pollution and has particular application to the containment and recovery of spilt oil.

One known form of oil pollution control system as disclosed in UK Patent Application No.

8000191 is a towed submersed perforated hose containing pressurised air. Air bubbles escaping through the perforations rise to the surface of the water, expanding as they do so to form a bubble barrier through which surface oil does not easily penetrate. The towed bubble barrier can be used to sweep a polluted area so that oil collected thereby can be recovered by an oil skimmer or it can be used to move surface oil from one area to another from where it can be left to disperse naturally without harm to the environment. It is also known to use static bubble barriers or booms to contain accidental spillage of oil, for example when charging or discharging oil tankers.

Difficulties have been experienced when using bubble barriers due to dispersion of the released air bubbles when operated in strong headway current while being towed or in strong tidal currents when operated in a static mode.

The object of the present invention to provide a system which provides means to control the released bubbles to increase the efficiency of the system.

According to the invention a system for containing and/or collecting oil on the surface of a body of water comprises a buoyancy means, a flexible skirt dependent therefrom so as to extend from the surface of the water to a submerged perforated hose member attached thereto and means for maintaining the perforated hose member beneath the surface of the water whereby in use gas under pressure is connected to the perforated hose member to provide a continuous upwardly expanding curtain of gas bubbles from the perforations which are guided to the surface of the water by the skirt to control the oil.

The means for maintaining the perforated hose member beneath the surface of the water could be provided by weighting the lower edge of the skirt by a chain or a water-filled hose extending therealong.

Preferably the buoyancy means is a gas-filled hose extending along the upper edge of the skirt.

Advantageously an upwardly extending fence is provided attached to the buoyancy hose to aid location of the gas bubbles at the surface of the water.

In one embodiment of the invention suitable for use as a static boom the skirt is planar.

Advantageously there are provided two perforated hose members, one extending along each side of the skirt and connected to a change-over valve whereby pressurised gas can be connected to the perforated hose which is on the upstream side of the skirt.

In another embodiment suitable for towing behind two vessels the skirt is made bell-shaped in the bight.

The invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 shows a schematic section taken through an oil pollution control barrier; Figure 2 is a schematic plan view of the oil control barrier towed behind two vessels; Figure 3 is a schematic section on the line Ill-IllofFigure 1; and Figure 4 shows a modification of Figure 1 for use as a static barrier in tidal waters.

Referring to Figures 1 to 3, the towed barrier system comprises vessels 1 and 2 towing the barrier 3 through water.

The barrier 3 comprises a 6" inside diameter rubber buoyancy hose 4. Attached thereto is the upper end of a flexible PVC skirt 5 8' in depth. A pocket 6 is provided along the bottom edge of the skirt 5 remote from the buoyancy hose 4. Located within the pocket 6 is a chain or a hose filled with pressurised water so as to maintain the skirt vertical when there is no flow of water thereagainst. Attached to one surface of the skirt 5 and situated and extending along the skirt i' above the lower edge thereof is a sleeve 7 suitable for supporting therein a 2" inside diameter flexible hose member 8. The hose member 8 is perforated along its length. Attached to the buoyancy hose 4 along a line diametrically opposed to the attachment line of the skirt 5 is a partially flexible 6" fence 9.The fence 9 is made sufficiently flexible so as to enable the buoyancy hose 4 to bend when towed while being sufficiently rigid to stand up above the surface 10 of the water.

An air hose 10 pressurised by means of a compressor is provided on each of the towing vessels 1 and 2 for connection to the respective ends of the buoyancy hose 4 and the perforated hose member 8. The skirt 5 is belled on the bight 11 to allow a smooth passage through the water on towing. The perforated hose member 8 is located on the upstream side of the skirt 5 so that pressurised gas bubbles 1 2 escaping from the perforations in hose member 8 expand and rise to the surface 10 of the water forming a barrier 1 3 of bubbles on the upstream side of the skirt 5 between the headway current 1 4 and the skirt 5.

The skirt 5 channels the bubbles 12 as they rise to the surface 10 of the water and thereby leads t6 the formation of an efficient bubble barrier 13. The efficiency of the bubble barrier 13 is further improved by the provision of the fence 9 which reduces the likelihood of the surface bubbles and hence any collected surface oil contaminant being washed over the buoyancy hose 4.

The general principle of operation of the invention whereby the formation of a barrier of gas bubbles on the surface of water to prevent the passage of an immiscible surface contaminant such as oil is well known. The present invention however provides a means for concentrating the bubble barrier and inhibiting its dispersal.

Compressed air is normally used to pressurise the buoyancy hose 4 and the perforated hose member 8.

The invention as described with reference to a towed barrier can be modified for use in a fixed barrier installation as shown in Figure 4. In this arrangement the belled skirt is replaced by a generally planar skirt 14. A perforated hose member 1 5 extending along the length of the skirt 14 is provided on each side of the skirt 14, supported in respective pockets 1 6. The two perforated hoses 1 5 are connected to a compressor via a change-over valve (not shown) such that the bubble barrier 13 location can be changed from one side of the buoyancy tube 4 to the other as appropriate on a change in the direction of tide or current to prevent passage of surface contaminants.

It will be apparent to those skilled in the art that modifications of the embodiments described are possible within the principle of the invention.

Claims

1. A system for containing and/or collecting oil from the surface of a body of water comprising a buoyancy means, a flexible skirt depending therefrom so as to extend from the surface of the water to a submerged perforated hose member attached thereto and weighting means for maintaining the perforated hose member beneath the surface of the water whereby in use gas under pressure is connected to the perforated hose member to provide a continuous upwardly expanding curtain of gas bubbles from the perforations which are guided to the surface of the water by the skirt to control the oil.

2. A system as claimed in claim 1 wherein the weighting means comprises a chain extending along the lower edge of the skirt.

3. A system as claimed in claim 1 wherein the weighting means comprises a water-filled hose extending along the lower edge of the skirt.

4. A system as claimed in my one preceding claim wherein the buoyancy means extends along the upper edge of the skirt.

5. A system as claimed on any one preceding claim wherein there is provided a fence attached to the buoyancy hose extending upwardly and along the hose.

6. A system as claimed in any one preceding claim wherein the skirt is planar.

7. A system as claimed in claim 6 wherein there is provided a further perforated hose, the two hoses being mutually parallel and located on respective opposed sides of the skirt and connected to a change-over valve such that pressurised gas can be selectably applied to either hose.

8. A system as claimed in any one of claims 1 to 6 wherein the central portion of the skirt is made bell-shaped.

9. A system as claimed in any one preceding claim wherein the perforated hose member is a flexible hose with perforations provided through the wall thereof.

10. A system for containing and/or collecting oil from the surface of a body of water substantially as described with reference to Figures 1 to 3 of the accompanying drawings.

11. A system for containing and/or collecting oil from the surface of a body of water substantially as described with reference to Figure 4 of the accompanying drawing.