GB1568636A

GB1568636A - Vessel and method for collection of oil or the like on water

Info

Publication number: GB1568636A
Application number: GB13268/77A
Authority: GB
Original assignee: SUBMARINE ENG AS
Current assignee: SUBMARINE ENG AS
Priority date: 1976-03-30
Filing date: 1977-03-29
Publication date: 1980-06-04
Also published as: NL7703415A; DE2713324A1; BR7701960A; FR2346209A1; JPS52129192A; IT1076269B

Description

(54) VESSEL AND METHOD FOR COLLECTION OF OIL OR THE LIKE ON WATER (71) Wei SUBMARINE ENGINEERING A/S, a Norwegian body corporation, residing at incognito Terrase 1, Oslo 2, Norway, do bereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly described in and by the following statement:- The present invention relates to a device for a collection of oil or the like on water, comprising a vessel equipped with propulsion and and a plurality of catchment arms extending outsvardly at an angle. The device is especially intended for use in connection with leakage from shipwrecked oil tankers.

offshore production plants for oil, etc.

The steadily increasing activity in connection with the exploration for oil, production, tránsportation and, further processing of gil involves great danger of pollution catastrophies. The oil tanker shipwrecks happened so far have shown beyond doubt that the oil pollution problems entailed can take enormous dimensions both ecologically and economically. Thus, it must be expected that total loss of supertankers with oil cargo or uncontrolled blowouts from oil wells which sooner or later will occur, will be able to give oil leakage amounts of such a magnitude that one hardly can imagine the extent of the resulting damage. In the case of a uncontrolled blowout the leakage may amount to several million tons.

Known devices have in common.. the fact that their capacity is very small in comparison to the oil leakage amounts associated with the above-mentioned accidents. Furthermore, they depend on calm sea: and. good weather conditions in order to function as intended.

These are considerable drawbacks, especially because such accidents are most likely to occur during unfavourable weather and wave conditions.

What is required is a device that alleviates the drawbacks, particularly by collecting large oil spills raore .effectively and permitting this to be done. under difficult weather cow ditions. Furthermore, such- a device should, in a standby condition, be able to serve other useful purposes.

According to the- present invention, there is provided a vessel, for use in collecting oil or the like floating on water, comprising a hull; a plurality of catchment arms attached to the hull so as to extend or be capable of extending outwards from the hull, each catchment arm having associated therewith at least one opening which-communicates with -an interior cavity of the hull, which cavity has the shape of a body of rotation; at least.one buoyancy tank; pumping means for the. discharge of liquid from the cavity; ballasting means; and controlling means for controlling the pumping means and/or ballasting means; wherein the arrangement is such that, i-n use, when oil or the like is being collected the catchment arms are or can be extended in the direction of motion the vessel, with each opening forward of the point of attachment of the catchment arm with which it is associated, and the controlling. means controls the pumping. .and/or ballasting means to keep the lower edges of said openings near the surrounding liquid level, and at all times during operation of the. vessel -at- least one buoyancy tank is; located partly above the level of the.

water.

For a better. understanding. of the present invention and to .show- more clearly how the same may be carried into effect,- reference will now be made, by way of example, to the accompanying drawings, in which: Figure. 1 shows a frontal. view. of a device according to the invention; - - Figure 2 shows the same -device seen from above: Figure 3 shows the device according to the invention seen partly in section from the side; Figure 4 shows a section taken along the line IV-IV in figure 3; and Figure 5 shows a section taken along the line V-V in figure 3.

The device - - ac.cording to, the. invention shown .in the figu.res - comprises- a vessel generally denoted by 1, which vessel has a hull 2 of generally symmetrical shape. At the broadest point of the hull 2 catchment arms 3 are arranged at opposite sides, said catchment arms extending at an angle outwardly from the hull and forwards in the direction of motion of the vessel.

The vessel 1 is further equipped with a main deck 4 and an upper deck 5 which advantageously may be used as landing site for a helicopter 6 suggested in broken lines in figure 3. At the forward edge of the upper deck 5 a pilot house 7 is arranged, and on top of this is placed a helicopter control house 8.

On the main deck life boats 9, anchor winches 10, deck cranes 11 and piping manifolds 12 for unloading the vessel are placed. In addition, crew quarters 13 are arranged between the main deck 4 and the upper deck 5.

As shown in Figure 4, the vessel has an inner cavity 14 formed as- a body of rotation.

The annular part between the hull 2 and the inner cavity 14 is subdivided mainly into buoyancy tanks 15 and pump rooms 16.

Pumps 17 with double drive units 18 are arranged in the pump rooms. The suction 19 of the pumps extends down towards the bottom 20 of the vessel, and the free end of the suction line is bent in a direction tangentially with the side wall of the inner cavity 14.

The pump discharge line 21 is subdivided into two branch-lines each being equipped with a shutoff valve 22, and each terminating in openings 23 in the side wall of the hull in a generally tangential manner.

Another discharge line 24 leads from the pump -17 into the inner cavity 14. Like the suction line 19, this discharge line is directed tangentially with the side wall of the inner inner cavity, but in opposite direction. The discharge line 24 is equipped with a control lable throttle and shutoff valve (not shown).

Immediately in front of the attachment point of the catchment arms 3 in the hull 2 openings 25 are arranged, the extent of which in vertical direction being less than the height of the nearest section of the catchment arms 3.

The size of the openings 25 is adjustable by suitable means (not shown), at least the lower edge of the openings being movable in vertical direction. Furthermore, the openings may be closed in their entirety, if desirable.

Channels 26 lead from the openings 25 to the inner cavity 14 of the vessel. The channels 26 extend at an angle with respect to the radial direction.

The function of the device according to the Invention will be described in the following with reference to the embodiment described above aed shown schematically in the draw ings.

Before oil collection is started, the internal cavity 14 of the vessel is filled with water until the water level outside reaches approximately half way up on the openings 25 which are closed. Thereafter, the internal liquid surface is brought to the same level by adjusting the amount of ballast water in the buoyancy tanks 15, whereupon the closures for the openings 25 are removed. The vessel 1 will now float stably in this equilibrium position.

Next, the pumps 17 are started. The pumps suck water in through the suction line 19 from the bottom portion of the inner cavity 14, and the shutoff valves 22 are set so that the water from the two pumps which are situated below the openings 25 flows out in a rearward direction, i.e. towards the left in Figure 4.

This will give rise to a reaction force which will move the vessel forwards, i.e. towards the right in Figure 3.

The unloading effect of the pumps gives rise only to a negligible reduction of level in the inner cavity 14 since the water pumped out is replaced by liquid flowing into the openings 25 and the inlet channels 26.

When the vessel 1 is moving through a oil spill a certain accumulation of oil will take place between the catchment arms 3, especially in the corners between the catchment arms 3 and the hull 2. This accumulation effect. is expected to be magnified by the soarms 3 and the hull 2. This accumulation effect is expected to- be magnified by the socalled wedge effect. The wedge effect consists mainly of the formation of a generally stationary, with respect to the hull, liquid portion near the hull, particularly near the openings 25. The vertical cross section of this liquid portion has the approximate form of a wedge, the wedge tapering off in the direction of the motion of the vessel. The wedge effect is therefore expected to lead to a multiplication of the thickness of the oil layer near the openings 25.This makes it relatively sirnple to adjust the openings 25 and possibly the ballast of the buoyancy tanks so that a major part of the liquid flowing into the openings 25 is constituted by oil even under unfavourable weather and wave conditions.

Since the buoyancy tanks 15 of the vessel are arranged as near as possible to its periphery, a very high moment of inertia in the waterline plane is obtained, and this moment of inertia, together with the large width of the vessel, give very good stability characteristics, particularly with respect to rolling, compared to ships of more conventional form. The mass of the large amount of liquid in the inner cavity 14 gives such a high inertia resistance against rolling and pitching motion that effective oil collection can be obtained even under very unfavourable weather and wave conditions. If the vessel is moving more or less transversly of the wind direction, the hull and the catchment arms will form lee which further enhances the oil collecting properties of the device according to the invention.

In Figure 4 two of the pump units 17 are shown having inner discharge lines 24 being directed tangentially along the side wall of the inner cavity 14. The suction lines of the pumps are also directed tangentially to said side wall, but in opposite direction with respect to the discharge lines. When the pumps are in service, water will be sucked in and ejected in the same tangential direction to the wall of the inner cavity, the result being that the liquid body in the inner cavity is brought to rotate therein. This rotation is contributed to by the liquid which flows in through the inclined channels 26. The centrifugal force caused by the rotation acts with different strengths on the water and oil particles in the imlowing liquid and thus helps to separate these.

Separation of water and oil particles is also caused by the difference in gravitational force to which they are subjected.

During oil collection, the water being pumped out is partly replaced by oil, and, due to the lower specific gravity of the oil, the draught of the vessel have tendency to decrease. This may be compensated for by filling ballast water into the buoyancy tanks 15 and/or by adjusting the inlet openings 25.

When the inner cavity has become so full of oil that sufficient separation no longer can be ascertained, the vessel is emptied of oil, for instance via the piping manifolds 12. Con currutlyr water is allowed to flow into the bottom portion of the vessel, making it ready for further operation as soon as it is emptied of oil. When it is necessary to move the vessel according to the invention quickly from one place to another, most of the liquid is pumped out of the vessel so that its draught and water resistance are reduced. The catchment arms 3 are hereby brought well clear of the water iiiface.

The- device according to the invention will usually be in standby condition, i.e. it will be stationed in or near an area where there is potential danger of oil pollution, for instance i offshore oil field. Since the device according to the invention represents a ctsiderable investment, it is desirable to be able to make use of it during most of the time it is not occupied by collecting oil spills. It has been found that the device in this respect is especially suited for living quarters for crew sat ysonnel on platform installations nearby due to its very good stability characteristics and large, easily usable deck space.The crew quarters on such platform installations are quite limited and there has long been a need for hotel facilities" at such oil fields. In case the oil collector according to the invention must be put to service as such, its inhabitants can quickly be evacuated by helicopter.

Due to its large pump capacity and good manoeuverability the device according to the invention is also well suited for firefighting purposes. In this capacity it will have another stand-by function.

In the embodiment shown the two pumping devices placed nearest the openings 25, i.e.

near the sides of the vessel, are used for emptying the inner cavity of the vessel and for propulsion of the vessel, while the pumping devices for and aft in the vessel are used for manoeuvering the vessel, for rotating the liquid in the inner cavity and for counteracting the rotation of the vessel induced by the rotating liquid inside. However, the pumping deaices may be interconnected so that they all contribute to the propulsion of the vessel, this being particularly desirable when the vessel is to be moved quickly from one place to another. Furthermore, it is clear that the vessel may be equipped with other forms propulsion means and that the vessel's own propulsion means may entirely or in part be replaced by tugboats or the like. The pumps 17 may also advantageously be arranged so that they may be used for emptying the buoyancy tanks 15 and for emptying the inner cavity.In addition, the pumping devices may advantageously comprise variable speed drive units. Furthermore, the pumps 17 may not all be identical. The propulsion pumps may for instance be of the axial type in order to give good efficiency, while the remaining pumps may be of a type giving higher head in order to be better suited for for instance firefighting. In addition, it is suggested according to the invention to arrange the drive unit so that it may drive two different pumps, either one at the time or both together, as desirable. Hereby it is possible to increase the flexibility of the vessel with a minimum of installed horsepower.

Even though the preceding embodiment shows a vessel formed as a body of rotation, it will be obvious for a skilled person that the Outer form of the vessel may be modified without departing from the idea of the invention. The hull may thus be given a more suitable shape from a water resistance standpoint, for example approximate drop form when received from above, and there may be more than one cavity provided, for instance two tanks could be provided, one of which may be used for coarse separation of oil while the other is used for further cleaning of the discharge water.

The embodiment shown has a diameter of the order of magnitude of 50 meters in order to give good sea-going characteristics and large collecting capacity. However, the device according to the invention may be produced to a smaller scale for use in protected waters, for instance harbour areas, where it will be especially suited for collection of oil spills and the like due to its very good manoeuverability.

It is not absolutely necessary to make the water-oil mass state in order to obtain the desired separation. It is expected, however, that rotation of the internal body or liquid will speed up the separation so that the flow rate through the device according to the invention, and thereby its capacity may be increased. Furthermore, the circulating mass inside the vessel will have some gyroscopic effect, thereby making the stability of the vessel even better.

Thus, it will be understood that the above described embodiment of the invention provides a oilspill collecting device which should be very useful, stable, easily manoeuvered, sea-going, efficient, simple and reliable compared to previously known devices.

In an alternative embodiment of the invention the catchment arms are arranged so that they extend in generally opposite direction. Such a vessel with one pair of arms would result if one of the arms 3 shown for instance in Figure 2 was pivoted backwards about 90;.

Concurrently, the opening 25 would have to be moved to the opposite side of the attachment point for the arm. By suitable control of the valves 22 and/or the drive units 18 the vessel could be brought to rotate while it is moving linearily, whereby oil is collected by the arm-s and led along these towards the openings in the hull.

WHAT WE CLAIM IS: I. A vessel, for use in collecting oil or the like floating on water, comprising a hull; a plurality of catchment arms attached to the hull so as to extend or be capable of extending outwards from the hull, each catchment arm having associated therewith at least one opening which communicates with an interior cavity bf the hull, which cavity has the shape of a-body of rotation; at least one buoyancy tank pumping means for the discharge of liquid from the cavity; ballasting means; and controlling means for controlling the pumping means and/or ballasting means, wherein the arrangement is such that, in use, -when oil or the like is being collected, the catch- ment arms are or can be extended in the direction of motion of the vessel, with each opening forward of the point of attachment of the catchment arm with which it is associated, and the controlling means controls the pumping and/or ballasting means to keep the lower edges of.said openings near -the surrounding liquid level, and at all times during operation of the vessel at least one buoyancy tank is located partly above the level of the water.

2. A vessel as claimed in claim 1 and including propulsion means.

3. A vessel as claimed in claim 1 or 2, wherein the full of the vessel has approximately equal lenght and width.

4. A vessel as claimed in claim 1, 2 or 3, wherein the hull of the vessel is formed as a body of rotation.

5. A vessel as claimed in any one of the preceding claims, wherein said at least one buoyancy tank is placed in a radial outer zone of the vessel.

6. A vessel as claimed in claim 4 or 5, wherein the catchment arms are attached near the widest part of the hull.

7. A vessel as claimed in any one of the preceding claims, wherein the ballasting means comprise at least some of the buoy ancy tanks and pumping means.

8. A vessel as claimed in any one of the preceding claims wherein the openings are located near the attachment points of the catchment arms.

9. A vessel as claimed in any one of the preceding claims, wherein the lower edges of said openings, in E - c generally main tainable at a level above the surrounding liquid level.

10. A vessel as claimed in any one of the preceding claims, including liying quarters with capacity for more than the vessel's own crew.

11. A vessel as claimed in any one of the preceding claims, including equipment for fighting fires remote from the vessel.

12. A vessel as claimed in any one of the preceding claims, wherein the pumping means constitute a part of the vessel's propulsion and/or manoeuvering means.

13. A vessel as claimed in-any one of the preceding claims, including a - helicopter landing space. - 14. A vessel as claimed in any one of the preceding claims including means for effecting rotation of-the liquid body in the-inner cavity with respect to the vessel 15. A vessel as claimed in any one of the preceding claims, wherein the pumping means comprise a drive unit which may be selectively coupled to one or more pump units.

16. A vessel as claimed in any one of the preceding claims, wherein one or more of the drive units for the pumping means - -be ve variable speed.

17. A vessel as claimed in any one of the preceding claims, wherein each catchment arm is directed generally in opposite direction of one of the other catchment arms,. and that the propulsion means are - arranged - to cause rotation of the-vessel during its propulsion; 18. A vessel for collecting oil or the like floating on water, substantially as herein befor described with reference to, and as shown in, the accompanying 'd?awings.

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Claims

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that rotation of the internal body or liquid will speed up the separation so that the flow rate through the device according to the invention, and thereby its capacity may be increased. Furthermore, the circulating mass inside the vessel will have some gyroscopic effect, thereby making the stability of the vessel even better.

Thus, it will be understood that the above described embodiment of the invention provides a oilspill collecting device which should be very useful, stable, easily manoeuvered, sea-going, efficient, simple and reliable compared to previously known devices.

In an alternative embodiment of the invention the catchment arms are arranged so that they extend in generally opposite direction. Such a vessel with one pair of arms would result if one of the arms 3 shown for instance in Figure 2 was pivoted backwards about 90;.

Concurrently, the opening 25 would have to be moved to the opposite side of the attachment point for the arm. By suitable control of the valves 22 and/or the drive units 18 the vessel could be brought to rotate while it is moving linearily, whereby oil is collected by the arm-s and led along these towards the openings in the hull.

WHAT WE CLAIM IS: I. A vessel, for use in collecting oil or the like floating on water, comprising a hull; a plurality of catchment arms attached to the hull so as to extend or be capable of extending outwards from the hull, each catchment arm having associated therewith at least one opening which communicates with an interior cavity bf the hull, which cavity has the shape of a-body of rotation; at least one buoyancy tank pumping means for the discharge of liquid from the cavity; ballasting means; and controlling means for controlling the pumping means and/or ballasting means, wherein the arrangement is such that, in use, -when oil or the like is being collected, the catch- ment arms are or can be extended in the direction of motion of the vessel, with each opening forward of the point of attachment of the catchment arm with which it is associated, and the controlling means controls the pumping and/or ballasting means to keep the lower edges of.said openings near -the surrounding liquid level, and at all times during operation of the vessel at least one buoyancy tank is located partly above the level of the water.
2. A vessel as claimed in claim 1 and including propulsion means.
3. A vessel as claimed in claim 1 or 2, wherein the full of the vessel has approximately equal lenght and width.
4. A vessel as claimed in claim 1, 2 or 3, wherein the hull of the vessel is formed as a body of rotation.
5. A vessel as claimed in any one of the preceding claims, wherein said at least one buoyancy tank is placed in a radial outer zone of the vessel.
6. A vessel as claimed in claim 4 or 5, wherein the catchment arms are attached near the widest part of the hull.
7. A vessel as claimed in any one of the preceding claims, wherein the ballasting means comprise at least some of the buoy ancy tanks and pumping means.
8. A vessel as claimed in any one of the preceding claims wherein the openings are located near the attachment points of the catchment arms.
9. A vessel as claimed in any one of the preceding claims, wherein the lower edges of said openings, in E - c generally main tainable at a level above the surrounding liquid level.
10. A vessel as claimed in any one of the preceding claims, including liying quarters with capacity for more than the vessel's own crew.
11. A vessel as claimed in any one of the preceding claims, including equipment for fighting fires remote from the vessel.
12. A vessel as claimed in any one of the preceding claims, wherein the pumping means constitute a part of the vessel's propulsion and/or manoeuvering means.
13. A vessel as claimed in-any one of the preceding claims, including a - helicopter landing space. -
14. A vessel as claimed in any one of the preceding claims including means for effecting rotation of-the liquid body in the-inner cavity with respect to the vessel
15. A vessel as claimed in any one of the preceding claims, wherein the pumping means comprise a drive unit which may be selectively coupled to one or more pump units.
16. A vessel as claimed in any one of the preceding claims, wherein one or more of the drive units for the pumping means - -be ve variable speed.
17. A vessel as claimed in any one of the preceding claims, wherein each catchment arm is directed generally in opposite direction of one of the other catchment arms,. and that the propulsion means are - arranged - to cause rotation of the-vessel during its propulsion;
18. A vessel for collecting oil or the like floating on water, substantially as herein befor described with reference to, and as shown in, the accompanying 'd?awings.