WO2010019081A1

WO2010019081A1 - Device and method for collecting oil spillage

Info

Publication number: WO2010019081A1
Application number: PCT/SE2008/050920
Authority: WO
Inventors: Mikael Hällström
Original assignee: Saab Ab
Priority date: 2008-08-13
Filing date: 2008-08-13
Publication date: 2010-02-18

Abstract

The invention relates to a device (10; 110) for collecting oil spillage in the sea, comprising a collecting member (30; 130), weight means (40; 140) for bringing or keeping the collecting member (30; 130) under the surface of the water, wherein the collecting member (30; 130) has a net-like configuration with a plurality of openings or passageways configured to let water through and prevent oil from passing through. The invention also relates to a method for collecting oil spillage in the water.

Description

DEVICE AND METHOD FOR COLLECTING OIL SPILLAGE

TECHNICAL FIELD

The present invention relates to a device for collecting oil spillage in water according to the preamble of claim 1. The present invention also relates to a method for collecting oil spillage in water according to the preamble of claim 11.

BACKGROUND ART

Pollution of seas due to oil spills is a major environmental issue. Oil spills may occur from e.g. an oil tanker being wrecked, or from e.g. a blowout in a submerged systems for pumping oil.

It is till common today to allow oil spillage from an accident at sea to float to the shore where it is collected manually/mechanically, which is extremely cost and time consuming.

There exist many different systems for taking care of such oil spills. A common technique for containing such oil spills is the use of booms being constituted by a floating means and a dense cloth provided with weights such that it is submerged. Booms are also used to temporarily encircling tankers being loaded and unloaded, sweeping areas for removing floating oil spillage, protecting beaches etc.

Such booms used especially in rough conditions such as cold climate, and adverse wind and wave conditions tend to function quite poorly. When there is a risk for ice formation the float may loose its buoyancy. The booms are further prone to brake when being towed. Other devices for collecting oil spillage exist. For example, WO 9417251 A1 discloses a device for collection of oil spillage and leakage from shipwrecks. The device comprises a hood adapted to be situated over the wreck, the hood being connected to a riser extending to a level below the sea surface, from where the spillage can be transferred to a collecting tank. In the upper section of the riser is formed a buoyancy body, preferably by means of being air filled. Inside the riser, from the lower edge of said buoyancy body and down to and including the hood, spillage can be collected and/or temporarily stored. A problem with such a device is that it is difficult to arrange the hood over the wreck.

OBJECTS OF THE INVENTION

An object of the present invention is to provide a device for collecting oil spillage which is efficient and easy to handle.

Another object of the present invention is to provide a method for collecting oil spillage which is efficient and easy.

SUMMARY OF THE INVENTION

These and other objects, apparent from the following description, are achieved by a device and method for collecting oil spillage which are of the type stated by way of introduction and which in addition exhibits the features recited in the appended independent claims 1 and 11 , respectively. Embodiments of the inventive device and method are defined in appended dependent claims 2-10, and 12.

Device for collecting oil spillage in the sea, comprising a collecting member, weight means for bringing or keeping the collecting member under the surface of the water, wherein the collecting member has a net-like configuration with a plurality of openings or passageways configured to let water through and prevent oil from passing through. This has the advantage that there will be much less resistance such that the collecting member may easily be towed in the water, or be submerged to the seabed to cover a potential oil leaking source. A more efficient collection of oil spillage in the water is possible.

According to an embodiment of the device the openings or passageways are dimensioned taking at least one of the following parameters into consideration: temperature of water into which the colleting means is submerged, viscosity of the oil to be collected, salt content of the water, and type of oil. By taking these parameters into consideration, efficient collection of oil spillage in the water may be performed during different weather conditions and by collection of different types of oil.

According to an embodiment the device further comprises at least one floatation element arranged to support the collecting member when said device is placed in water. This facilitates holding the collecting member close to the surface.

According to an embodiment of the device, the device has a boom-like configuration, wherein said floatation element is an elongated and flexible element connected along its longitudinal length to an upper end of the portion of the collecting member such that, when the device is placed in water, the collecting member is submerged substantially vertically in the water, an opposite lower portion of the collecting member being at a certain level underneath the water surface, the floatation element floating on the water.

According to an embodiment of the device the floatation element is arranged to receive a non-condensable gas. Hereby the risk of the device sinking due to cold temperature and ice formation is reduced, thus making the device more efficient, and durable. According to an embodiment the device further comprises control means for controlling the boom like configuration when towed by means of a vessel, e.g. a boat, said control means comprising a first control line connected to a first end of the elongated floatation element and a second control line connected to a second end of the floatation element, and a control member connected to the second end of the floatation element, the first and second control line being connected to the vessel, wherein the control member is configured such that during towing of the boom-like configuration it is controllable by means of the control lines such that it can follow the shore line. Hereby collection of oil spillage may be performed close to the shore line without the risk of damaging the boat. Thus a more efficient collection of oil spillage in the water is facilitated.

According to an embodiment of the device is dimensioned such that when the device is put outstretched into the water with the collecting member, the weight means will bring the collecting member to the seabed, and when oil from a submerged oil leaking source covered by the collecting member rises from underneath the collecting member, the device will rise to the water surface. This leads to an efficient way of collecting oil leaking from a potential oil leaking source at the seabed.

According to an embodiment of the device the collecting member is flexible and configured in such a way that when oil rises from underneath the collecting member, the collecting member captures and substantially surrounds the oil. This oil is thus efficiently collected and easy to take care of.

According to an embodiment the device further comprises a pipe connecting member centrally arranged at the collecting member through which oil may be sucked, the connecting member being connectable to an oil removal means, for example a hose, by means of which oil collected with the device may be removed. This makes the removal of the oil easier. According to an embodiment the device further comprises a warning means, for example a warning light, arranged at the collecting member such that when the device has risen to the water level by means of oil rising towards the surface, the warning means will warn e.g. ships and indicate location of the device.

Method for collecting oil spillage in the sea using a device according to any of claims 1-3, 7-10, comprising the steps of: outstretching the collecting member such that it lies flat on the surface; releasing the device such that it is submerged covering a potential oil leaking source on the seabed.

According to an embodiment the method further comprises the step of, after a leakage of oil causing the device to rise to the surface, removing the collected oil from the device.

BRIEF DESCRIPTION OF THE DRAWINGS

A better understanding of the present invention will be had upon the reference to the following detailed description when read in conjunction with the accompanying drawings, wherein like reference characters refer to like parts throughout the several views, and in which:

Fig. 1a schematically shows a front view of a device for collecting oil spillage according to an embodiment of the present invention;

Fig. 1 b schematically shows a side view of the device in fig. 1a;

Fig. 2 schematically shows a plan view of an arrangement for collecting oil spillage by means of the device in fig. 1a and 1 b.

Fig. 3 schematically shows a plan view of a device for collecting oil spillage according to an embodiment of the present invention, in a first method step of an application; Fig. 4 schematically shows a side view of an arrangement for collecting oil from a blowout in a submerged system by means of the device in fig. 3, in a second and third method step;

Fig. 5a schematically shows a plan view of another arrangement for collecting oil spillage from a ship wreck by means of the device in fig. 3; and

Fig. 5b schematically shows a side view of the arrangement in fig. 5a during a method step.

DETAILED DESCRIPTION

Fig. 1a shows schematically a front view of a device 10 for collecting oil spillage according to an embodiment of the present invention, and fig. 1b shows schematically a side view of the device 10 in fig. 1a.

The device 10, having a boom-like configuration, comprises an elongated floatation element 20 having a first end 22 and a second end 24. The floatation element 20 has according to an embodiment a substantially circular cross section. The floatation element 20 is a flexible element. The floatation element 20 has an outer water proof cover 26. The cover 26 or jacket of the floatation device is preferably of a diffusion tight material. According to an embodiment the floatation element 20 is when operated filled with a non- condensable gas inside the cavity 28 formed by the cover 26, for example dry air. In comparison having the floatation element filled with conventional air, which may condense and during cold conditions form ice such that the device 10, i.e. the boom-like configuration 10, sinks, the non-condensable gas results in a floatation element 20 being more resistant to rough and cold weather conditions and less prone to sink. The floatation element 20 may be one single piece or a number of floatation portions linked together.

The device 10 further comprises a flexible collecting member 30 or net member 30 having a net-like configuration with a number of openings or passageways for allowing flow of water therethrough and preventing flow of oil therethrough. The net member 20 has an upper portion 32 or end 32 and an opposite lower portion 34 or end 34, and side portions 36, 38. The upper portion 32 has an extension substantially corresponding to the extension of the elongated floatation element 20, the upper portion 32 being attached longitudinally to the elongated floatation element 20.

The configuration, e.g. size, of the openings is depending on parameters such as water temperature, viscosity of the oil, type of oil, e.g. heavy oil which has high viscosity, diesel oil which has low viscosity, etc., and amount of salt in the water. According to an embodiment the size of the openings are smaller the higher the temperature of the water. According to an embodiment the size of the openings are smaller the lower the viscosity/density. According to an embodiment the size of the openings are smaller the less amount of salt in the water. Thus, cold water, oil of high viscosity and high salt level in the sea results in a net-like configuration having relatively larger openings or passageways.

The material of the net member 30 is chosen to withstand rough conditions such as cold water, big waves, debris, ice etc. The net member 30 should be durable so that it can be maintained in a state of readiness in a submerged position for collection of spillage of oil over a long period of time. The net member 30 should be flexible such that it can receive the oil spillage, and, when not in use, be easily stored away, e.g. folded. The net member 30 is thus designed to be easy to handle.

The device further comprises weight means 40 arranged so as to keep the net member 30 substantially vertical below the surface when placed in water, such that the lower portion 34 of the net member 30 is located substantially straight underneath the floatation element 20. The net member 30 is thus weighted. The net member 30 is according to this embodiment weighted by means of weight members 40 having a gravity significantly greater than that of water. The weight members 40 are attached to the lower portion 34 of the net member 30.

Weight means may according to an alternative be a rim, flexible wire or the like acting as the lower portion extending along the extension of the net member 30 and thus the floatation element 20, having a gravity significantly greater than that of water. According to another alternative, the net member 30 itself may have a gravity significantly greater than water, thus acting as the weight means.

The dimensions of the device 10 depends on the application. The net-like configuration of the net member facilitates using a much wider collecting member 30 or net member 30, e.g. up to 200-300 meters wide, the floatation element 20 consequently being of the same length. The height of the net member 30 may according to an embodiment be in the range of 1-3 meters.

The floatation element 20 may according to an embodiment be 0,5-3 meters in diameter.

Fig. 2 shows schematically a plan view of an arrangement I for collecting oil spillage by means of the device in fig. 1a and 1 b.

The arrangement I comprises the device 10 and a vessel 50, e.g. a boat 50, for towing the device 10, i.e. the boom-like configuration. The arrangement I further comprises a control mechanism 60, 70, 80 for controlling the boom- like configuration 10 such that it may be towed close to a shore line S.

The control mechanism comprises a first control line 60 connected between the vessel 50 and the first end of the floatation element 20. The control mechanism further comprises a second control line 70, which is connected between the vessel 50 and the second end 24 of the floatation element 20. The first end 22 of the floatation element 20 is closer to the vessel 50 than the second end 24 of the floatation element 20. Thus the first control line 60 is shorter than the second control line 70. The control mechanism further comprises a control member 80, connected to the second end of the floatation element 20.

The control member comprises wings or rudders for controlling the control member 80. The control member 80 is controlled by means of the first control line 60 and the second control line 70. The first and second control lines 60, 70 are provided with strain gauges so as to balance the tensile stress in the control lines 60, 70 in order to maximize the effect.

The control mechanism is arranged such that the control member 80 urges the device 10, i.e. the boom-like configuration 10, sideways to the direction of travel such that the boom-like configuration 10 follows the shore line S. The control mechanism is operated from the vessel 50.

Thus, the device 10, i.e. the boom-like configuration 10, when connected to the vessel 50 by means of the first and second control lines 60, 70, is preferably arranged obliquely behind the vessel 50, displaced relative to the longitudinal direction of the vessel 50. The first control line 60 thus forms an angle relative to the longitudinal direction or direction of travel T of the vessel 50 that is smaller than the angle formed by the second control line 70 relative to the longitudinal direction or direction of travel T of the vessel 50.

The speed of the vessel 50 is a decisive factor or parameter. The speed is optimized such that it is just below the speed where the oil spillage is allowed through the openings of the net-like configuration, such that no oil spillage is allowed through, and yet a high the oil is collected at a high speed and thus efficiently. The height or depth of the net member 30 is also a parameter to pay attention to. A deeper net member 30 facilitates collecting more amount of oil spillage, but renders more resistance in the water. These parameters are optimized.

When operated for collecting oil the vessel 50 travels at a distance from the shore line S as shown in fig. 2. The control mechanism 60, 70, 80 controls the device 10 by means of the control lines 60, 70 and the control member 80 such that the device 10, i.e. the boom-like configuration 10, follows the shore line S. This is evident from fig. 2, where the vessel 50 is towing the boom-like configuration 10, and the control mechanism controls the device 10, i.e. the boom like configuration, such that it follows the shore line S, such that the device 10 collects oil spillage O.

The oil spillage O collected by means of the arrangement I is then taken care of in a conventional way.

The net-like configuration of the net member 30 of the device 10 has the effect that the device 10, when towed, gives much less resistance in the water in comparison to a conventional boom. This results in less ware of the device 10, and thus increased endurance and thus increased life time. Further, the towing may be performed in a much higher speed due to the net- like configuration, thus rendering collection of oil spillage more efficient. The net-like configuration in combination with the floatation element 20 filled with non-condensable gas facilitates operation in rough conditions and bigger waves.

Thus a more efficient collection of oil may be achieved by means of the arrangement I, as oil close to the shore line may be collected.

Fig. 3 shows schematically a plan view of a device 110 for collecting oil spillage according to an embodiment of the present invention, applied in a first method step.

The device 110 comprises a collecting member 130 or net member 130 having a net-like configuration with a number of openings or passageways for allowing flow of water therethrough and preventing flow of oil therethrough. The net member 130 is flexible.

The configuration, e.g. size, of the openings is depending on parameters such as water temperature, viscosity of the oil, type of oil, e.g. heavy oil which has high viscosity, diesel oil which has low viscosity, etc., and amount of salt in the water. According to an embodiment the size of the openings are smaller the higher the temperature of the water. According to an embodiment the size of the openings are smaller the lower the viscosity/density. According to an embodiment the size of the openings are smaller the less amount of salt in the water. Thus, cold water, oil of high viscosity and high salt level in the sea results in a net-like configuration of the net member 130 having relatively larger openings or passageways.

The material of the net-like configuration of the net member 130 is chosen to withstand rough conditions such as cold water, big waves, debris, ice etc. The net member 130 should be durable so that it can be maintained in a state of readiness in a submerged position for collection of spillage of oil over a long period of time. The net member 130 should be flexible such that it can receive the oil spillage, and, when not in use, be easily stored away, e.g. folded. The net-like configuration of the net member 130 is thus designed to be easy to handle.

The net member 130 has according to this embodiment a substantially square shape. The net member 130 may however have any suitable shape such a circular, rectangular, triangular, pentagonal etc. depending on application, storage etc. The size of the net member 130 depends on the application, and could according to one example have a size of 100x100 m.

The device 110 further comprises weight means 140 having a gravity significantly greater than water. According to this embodiment the weight means 140 is constituted by weight members 140 arranged circumferentially at the net member 130. The weight members 140 are dimensioned such that the net member 130, when put in water substantially outstretched, will submerge, i.e. sink towards the seabed remaining substantially outstretched. The weight members 140 are further dimensioned such that, when oil is floating upwardly underneath the net-like configuration of the net member 130, the net-like configuration is rising to the surface. The weight means 140 may according to an alternative be a rim, flexible wire or the like acting as the circumferential support of the net member 130 having a gravity significantly greater than that of water. According to another alternative the net member 130 itself may have a gravity significantly greater than water, thus acting as the weight means.

The device 110 further comprises a connection pipe member 160 arranged centrally at the net member 130. The connection pipe member 160 is configured such that a hose or the like may be connected thereto so as to remove oil spillage collected by means of the net member 130.

The net member 130 preferably comprises a flexible circumferential rim 132 acting as a support of the net-like configuration of the net member 130 so as to hold the net-like structure together.

The device 110 is configured such that when oil is rising from underneath the submerged net-like configuration of the net member 130 the flexible net-like configuration is arranged to surround the oil, the weight members 140 holding down the circumferential portion, i.e. rim 132, of the net member 130.

According to one embodiment the device 110 comprises a floatation element 120 centrally arranged at the net member 130 in connection to the connecting pipe member 160 so as to control the device 110.

Fig. 3 shows the device 110 in a first step S1 being outstretched by means of vessels 150, e.g. small boats 150. In this example four boats, one in each corner of the net member 130, are stretching the net member 130 so that it is outstretched. The net member 130 is outstretched in a position straight above the submerged potential oil spillage source, e.g. a submerged oil drilling station, or a ship wreck.

In a second step, not shown here, the device 110 is released from the vessels and is submerged by means of the weight members 140, towards the potential oil spillage source. The step of arranging the device 110 on the potential oil spillage source is preferably performed during calm weather conditions.

Fig. 4 shows schematically a side view of an arrangement Il for collecting oil from a blowout in a submerged oil drilling system by means of the device 110 in fig. 3.

A submerged oil drilling system 200 for drilling oil below the seabed B is arranged at the seabed B.

The device 110 has been arranged on the potential oil spillage source which according to this application is a submerged oil drilling system 200 or station 200. The device 110 has been submerged by means of the weight member 140 during a second step S2 and has reached the position covering the oil drilling system 200. The weight members 140 are resting on the seabed B, holding the net member 130 in position, so that it covers the oil drilling system 200.

If a blowout occurs on the oil drilling system 200 such that oil is pumping out into the sea the device 110 is configured such that when the oil is rising from the submerged oil drilling system 200 underneath the submerged net-like configuration of the net member 130, the flexible net-like configuration is during a third step S3 lifted upwards by means of rising the oil and surrounds the oil, the weight members 140 holding down the circumferential portion 132 of the net-like configuration.

During this step the device 110 rises to the surface so that the connecting pipe member rises above surface level. The floatation element 120 arranged in connection to the connecting pipe member 160 controls the surfacing of the connecting pipe member 160.

In a fourth step, not shown, the oil is removed from the device 110, preferably by means of connecting e.g. a hose to the connecting pipe member. Fig. 5b shows an embodiment of this step in another application. In an embodiment the connecting pipe member is arranged such relative to the oil drilling system that the oil drill is partly surrounded by the pipe connecting member.

The device 110 further comprises a warning light 125 arranged in connection to the floatation element 120 such that when the device, i.e. the floatation element 120 is at sea level, ships or the like may be warned.

Fig. 5a shows schematically a plan view of an arrangement III for collecting oil spillage from a ship wreck by means of a device 110 according to fig. 3, and fig. 5b shows schematically a side view of the arrangement in fig. 5a during an oil collecting method step, when the tanker is leaking oil.

A ship wreck 300, i.e. a submerged oil tanker 300 is resting on the seabed B. The device 110 has been arranged on the potential oil spillage source which according to this application is an oil tanker 300 resting on the seabed B. In this example, due to the size of the tanker 300, three devices 110 have been arranged such that they together substantially cover the oil tanker. The arrangement III is done by performing the first step and second steps according to fig. 3 and 4, for each device 110. Thus, the devices 110 have been submerged by means of the weight members 140 during the second step, and have reached their respective position covering the oil tanker 300. The weight members 140 are resting on the seabed B, holding the net member 130 in position, so that it covers the oil tanker 300.

In stead of having a number of separate oil collecting devices 110, several net members 130 may according to an alternative embodiment be joined together so as to cover a large surface like an oil tanker. The net member 130 may of course be dimensioned such that it covers also very big areas as a single piece, but care should be taken to the handling of the device 110.

If the oil tanker 300 is leaking oil such that oil is spilled into the sea the device 110 is configured such that when the oil is rising from the oil tanker 300 underneath the submerged net-like configuration of the net member 130, the flexible net-like configuration is during a third step lifted upwards by means of the oil and surrounds the oil, the weight members 140 holding down the circumferential portion of the net member 130.

During this step the device 110 rises to the surface W so that the connecting pipe member 160 rises above surface level. The floatation element 120 arranged in connection to the connecting pipe member 160 controls the surfacing of the connecting pipe member 160.

In a fourth step S4 the oil is removed from the device 110 by means of connecting e.g. a hose 170 to the connecting pipe member 160. The connection between the connecting pipe member 160 and the hose 170 may be of the type used in fire hydrants. The hose 170 preferably is of a type suitable for suction of the oil spillage. The oil is thus pumped into e.g. a ship 180 suitable for receiving the oil, and thus, the oil of the leaking tanker may be taken care of.

As an additional safety precaution, in order to avoid potential oil not collected by means of the net member 130, e.g. oil slipping between two net members 130, a boom-like configuration, e.g. according to the device in fig. 1a and 1b, or a number of boom-like configurations connected to each other may be arranged to surround an area sufficient to prevent oil escaping the location of the wreck or other potential oil spillage source such as the submerged oil drilling system according to the arrangement in fig. 4. A boom-like configuration is schematically shown in fig. 5b for illustrative purposes, the dimensions and location not being according to scale in comparison to the device 110 for collecting oil.

The foregoing description of the preferred embodiments of the present invention has been provided for the purposes of illustration and description. It is not intended to be exhaustive or to limit the invention to the precise forms disclosed. Obviously, many modifications and variations will be apparent to practitioners skilled in the art. The embodiments were chosen and described in order to best explain the principles of the invention and its practical applications, thereby enabling others skilled in the art to understand the invention for various embodiments and with the various modifications as are suited to the particular use contemplated.

Claims

1. Device (10; 110) for collecting oil spillage in the sea, comprising a collecting member (30; 130), weight means (40; 140) for bringing or keeping the collecting member (30; 130) under the surface of the water, characterized in that the collecting member (30; 130) has a net-like configuration with a plurality of openings or passageways configured to let water through and prevent oil from passing through.

2. Device according to claim 1 , wherein the openings or passageways are dimensioned taking at least one of the following parameters into consideration: temperature of water into which the colleting means is submerged, viscosity of the oil to be collected, salt content of the water, and type of oil.

3. Device according to claim 1 or 2, further comprising at least one floatation element (20; 120) arranged to support the collecting member (30; 130) when said device is placed in water.

4. Device according to claim 3, the device having a boom-like configuration, wherein said floatation element (20) is an elongated and flexible element connected along its longitudinal length to an upper end of the portion (32) of the collecting member (30) such that, when the device (10) is placed in water, the collecting member (30) is submerged substantially vertically in the water, an opposite lower portion of the collecting member (30) being at a certain level underneath the water surface, the floatation element floating on the water.

5. Device according to claim 3 or 4, wherein the floatation element (20) is arranged to receive a non-condensable gas.

6. Device according to claim 4 or 5, further comprising control means (60, 70, 80) for controlling the boom like configuration (10) when towed by means of a vessel (50), e.g. a boat, said control means comprising a first control line (60) connected to a first end (24) of the elongated floatation element (20) and a second control line (70) connected to a second end (24) of the floatation element (20), and a control member (80) connected to the second end (24) of the floatation element (20), the first and second control line (60, 70) being connected to the vessel, wherein the control member (80) is configured such that during towing of the boom-like configuration it is controllable by means of the control lines (60, 70) such that it can follow the shore line.

7. Device according to any of claims 1-3, wherein the device (110) is dimensioned such that when the device (110) is put outstretched into the water with the collecting member (130), the weight means (140) will bring the collecting member (130) to the seabed (B), and when oil from a submerged oil leaking source (200; 300) covered by the collecting member (130) rises from underneath the collecting member (130), the device (110) will rise to the water surface (W).

8. Device according to claim 7, wherein the collecting member (130) is flexible and configured in such a way that when oil rises from underneath the collecting member (130), the collecting member (130) captures and substantially surrounds the oil.

9. Device according to any of claims 1-3, 7-8, further comprising a pipe connecting member (160) centrally arranged at the collecting member (130) through which oil may be sucked, the connecting member (130) being connectable to an oil removal means, for example a hose, by means of which oil collected with the device may be removed.

10. Device according to any of claims 1-3, 7-9, further comprising a warning means, for example a warning light, arranged at the collecting member (130) such that when the device has risen to the water level by means of oil rising towards the surface, the warning means will warn e.g. ships and indicate location of the device.

11. Method for collecting oil spillage in the sea using a device according to any of claims 1-3, 7-10, comprising the steps of:

- outstretching the collecting member such that it lies flat on the surface;

- releasing the device such that it is submerged covering a potential oil leaking source on the seabed;

12. Method according to claim 11 , comprising the further step of:

- after a leakage of oil causing the device to rise to the surface, removing the collected oil from the device.