NO333108B1 - Chemical spill collection system - Google Patents

Abstract

It discloses a collection system for chemical spills, comprising an elongate, projecting catch arm equipped with at least one pontoon (14) adapted to be pulled by a vessel, in which contaminants floating on or in a water surface (50) are caused to flow along the pontoon (14) and to a collection device (20) for collecting the chemical spill. The at least one pontoon (14) is provided with a cloth (30, 30 ') lying around the pontoon (14), the cloth having a lower part (32, 32') projecting from the pontoon below the water surface (50) to delimiting a surface layer of chemical and water from underlying water masses, and for directing the chemical to the collecting device (20), and that a rope network (18) is connected to the cloth (30, 30 ') for pulling the cloth (30, 30') and the pontoon (14) in the direction of travel.

Description

The present invention relates to a collection system for chemical spills, comprising an elongate, projecting grab arm equipped with at least one pontoon adapted to be towed by a vessel, wherein pollution floating on or in a water surface is caused to flow along the pontoon and to a collection device for collection of the chemical spill, and where at least one pontoon is equipped with a sheet that lies around the pontoon.

The aim is to create a system for collecting chemicals in the form of oil after discharge. The system is based on fishery technology solution models for towed fishing gear, and which today are operated in almost all kinds of weather, in any case under weather conditions where oil is on the surface. The essence of these solutions is that forces are taken up and distributed through a framework of ropes, so that more delicate parts of the construction, such as tarpaulin, are not stressed to the same extent. Modern wire ropes have a significantly greater strength than stainless steel, and can be used throughout the system.

The system roughly comprises one or two pontoons and a canvas surface which is set from a drum and which is kept stretched out next to a vessel by means of a rope network attached to the bow, as well as a pump well attached to the end of the pontoon(s) and which is towed using of a line from the bow of the vessel. For example, for a 90 m vessel, a total width of the system of 50 m can be aimed at, but such a vessel can also operate two systems, one on each side, so that the total collection width is 100 m. The canvas is held up by and encloses a or two sausages (pontoons) made of, for example, Hypalon-covered polyester cloth. The oil is collected by a horizontal or near-horizontal planer-like edge or slit at the leading edge of the cloth "shaving" the oil from the surface. The oil is then led along the pontoon and into the back of the pump well, where it is pumped to the vessel by a skimmer or a fish pump.

From known patent literature, reference is made to NL 7705258 A and EP 0129279 A1, both of which deal with a vessel with a grab arm having a channel for directing oil towards a collection point. From US 2006/0201867 A1 it is known to guide the oil along a catch arm using a rotating screw.

DE 3344597 A1 shows a catch arm in the form of a pontoon with the shape of an airplane wing, and where oil is guided inside the pontoon.

Furthermore, US 3559760 A and US 4673497 A show the use of canvas bags for collecting and storing oil, respectively. US 3612280 A shows a vessel with elongated, projecting booms, and US 4096700 A shows an oil bilge with up to two buoyancy bodies with a submerged canvas for collecting oil spills.

The present system is intended to be used both for oil spills from shipwrecks and other accidental discharges from vessels, and for oil spills from oil installations for production and onward transport. The system is based on the fact that oil usually has a density (approx. 0.8-0.9 g/cm<3>) that is less than seawater (approx. 1.03 g/cm<3>), and will therefore be on the surface as long as the weather conditions do not drag the oil under due to turbulence. However, the invention can be used for the collection of all chemicals and also other heavy-flowing particulate substances that "float" in a similar way.

The system is often asymmetrical in that it leads the oil from the outer edge and continuously backwards and inwards until the oil flow ends in a pump well with an open bottom, so that water accompanying the oil can exit through the bottom of the pump well, while the oil remains on the surface in the pump well and can be pumped on board the vessel continuously.

The system can be self-propagating (for example between approx. 30 and 60 degree angle between the direction of travel and the pontoon) in that the fluid pressure along the boom brings it out from the forward side, while it is held in place by the towing resistance in the pontoon (e), and also by the pump well system which is suspended from a rope in the direction of travel.

It is an aim of the present invention to produce a more efficient collection system for chemicals, such as oil, which float on or in the water surface.

The above-mentioned purpose is achieved with a collection system as stated in independent claim 1, in that the canvas has a lower part that protrudes from the pontoon below the water surface to delimit a surface layer of chemical and water from underlying bodies of water, and to lead the chemical to the collection device, and that a rope network is connected to the canvas to pull the canvas and pontoon in the direction of travel.

Alternative designs are specified in the independent claims 2-12.

The canvas is preferably arranged around the pontoon, in which the lower part can be designed as a skirt that projects mainly horizontally below the water surface, and an upper part of the canvas can project mainly horizontally from the pontoon above the water surface and be arranged to function as a splash screen.

The rope network or the lower part of the canvas may be equipped with plumb bobs designed to regulate the depth of the canvas depending on rope speed.

In a further embodiment, the fender can be equipped with a second pontoon, in which the second pontoon is arranged in front of said at least one pontoon.

The cloth can be arranged around both pontoons so that an at least partially closed space is formed between the pontoons, and the lower part of the cloth can be equipped with several slit openings to delimit the surface layer of chemicals and water from underlying water masses.

The lower part of the canvas, in an area between the slot openings and the pontoon, can be fitted with lead weights or lead lines. In an area adjacent to the lead solder, there may be several outlet openings for excess water.

A number of straps can be arranged around one or both pontoons, and be connected by the rope network. Furthermore, a number of straps or flat bands may run between the first and second pontoons and be connected to the rope network.

A rear part of the lower part of the canvas can be attached in front of the rear pontoon, in an area mainly above the water surface. A canvas chute can also be arranged under the pontoon, where the canvas chute is closed at the rear and at least partially open at the front, and the canvas chute can be attached at the front with flat tape to the lower part of the canvas.

The collection device is advantageously a pumping well designed to receive chemical and water flowing inwards along the boom, and to pump mainly chemical to the vessel or a tow bag.

In the latter case, water can escape through a bottom outlet. It can also be advantageous to lead booms/pontoons directly into a tow bag, especially for small systems adapted to small and simply equipped vessels.

The invention will now be described in more detail with the help of the attached figures, in which: Figure 1 shows a principle sketch of a vessel equipped with a simple tentacle according to the invention, and shown without an overlying canvas. Figure 2 shows a principle sketch of a vessel equipped with a simple grab arm according to the invention, and shown with an overlying canvas. Figure 3 shows a principle sketch of a vessel equipped with a double tentacle according to the invention, and shown without an overlying canvas Figure 4 shows a principle sketch of a vessel equipped with a double tentacle according to the invention, and shown with an overlying canvas.

Figure 5 shows a section of a single pontoon solution according to the invention.

Figure 6 shows a section of a topongtong solution according to the invention.

Figure 7 shows a further variant of the solution shown in Figure 6.

Figure 8 shows a section of a fabric area with slit openings.

Figure 9 suspension and rope attachment in front of a pontoon.

Figures 10 and 11 show a pump well, seen from above and from the side, respectively.

As figures 1, 2 and 5 show, a first embodiment of the present invention comprises a grab arm 10 which projects obliquely from a vessel 12. The grab arm in this embodiment preferably comprises a pontoon 14 which is surrounded by a cloth 30. The cloth 30 can lie around the pontoon 14 as Figure 5 shows, so that the canvas lies in a u-shape around the pontoon 14. The canvas 30 is further connected by a rope network 18 with several branches which are attached successively in the lengthwise direction of the canvas.

The principle for collecting chemicals, such as oil, is that a lower part 32 of the canvas 30 forms a substantially horizontal canvas surface, such as a skirt, in front of the pontoon

14 and delimits the surface layer of oil and water from underlying water masses. The water surface is shown with the reference number 50. The water hits the pontoon 14 and is reflected backwards and outwards, and the oil lies on top of this water layer and is brought backwards and towards a pump well 20. Surplus water can flow out over the edge of the canvas, while the surface layer of oil flows backwards along the pontoon 14 and ends in the pump well 20. A "river" is thus formed along the pontoon 14, and on top of this "river" the oil flows. The horizontal canvas surface 32 is attached at the front in a rope network 18 towards the bow of the vessel 12. This rope network 18 pulls the canvas 30 and the pontoon 14 in the direction of travel. The ropes 18a can be equipped with lead weights 42 just in front of the fasteners against the canvas 30, or alternatively the lower part 32 of the canvas can be equipped with lead weights. This is to regulate the depth of the canvas in relation to towing speed, which can for example be between 3 and 5 knots.

As Figure 5 shows, the upper part 34 of the canvas can similarly protrude horizontally from the pontoon 14 and above the water surface 50 so that a form of splash screen is formed. Figure 2 the pontoon 14 with the upper canvas surface 34. The projection in front of the pontoon 14 can be the same size for both canvas surfaces 32, 34 so that the upper and lower canvas edges are directly above each other, but the canvas 30 can be wider (for example approx. 4 m) towards the pump well than at the outer end (for example approx. 0.5 m). Figures 3, 4 and 6 show a second variant of a grab arm 10' with two pontoons 14, 16. The grab arm 10' is correspondingly fixed in the rope network 18. The second variant is based on the same principle (surface oil is scraped off together with water and forms a "river" backwards along the pontoon), but is designed somewhat differently. The leading pontoon 16 can function as a wave damper, while positioning several intake slits 40 in the canvas 30' at the right depth to catch the oil on the surface, which can replace the lead weights on the ropes. The oil and some water are pressed under the leading pontoon 16 and through the slits 40 in the lower part of the canvas 32'. In the space between the pontoons 14, 16, oil and water will form a river backwards as in the first variant, and excess water can either be released through slits 44 at the rear edge of the space between the pontoons, or flow out through the bottom of the pump well 20.

Shown in Figure 6 is a first variant of the topongtong solution. The canvas 30' surrounds both pontoons 14, 16 so that a substantially closed space is formed between the pontoons. The canvas 30' is preferably attached to the foremost pontoon 16 with several straps 36, and straps 38, 38' can also extend between the two pontoons 14, 16. As mentioned, the lower part 32' is equipped with several slit openings 40 which extend in the longitudinal direction of the cloth. Figure 8 shows an example of slits 40 in the lower part 32' of the cloth 30'. The lower part 32' of the canvas 30' can further be equipped with a plumb bob or a lead line 42' to regulate the position of the lower part 32' in the water, so that the slits 40 have the best possible effect in connection with the "planing" of oil in the water surface .

The front pontoon 16 can be surrounded by a network of fastening straps which are in turn attached to the rope network 18, and can have attachment points for the rope network at 2-3 m intervals. The canvas 30' surrounds both pontoons, and may have corresponding attachment points to the rope network with the front pontoon.

When applying the present principle, the pontoons 14, 16 only need to be attached in the flat straps 36 around the pontoon 16 with a few carabiner hooks 52 to be held in place. During operation, the water pressure will keep them where they should be. The rope network 18 can also be attached to the canvas with carabiner hooks. This makes it easy to replace components, as well as to dismantle the equipment for cleaning. Each component is also so light and small that it can be handled quite easily.

Figure 7 shows a further variant of the topongtong solution. The lower part 32' of the canvas can be attached in front of the pontoon 14, which is shown with reference number 32a. To help with the spreading force, a chute 60 of fabric can be fitted under the pontoon 14 to give greater force across the towing direction. This chute 60 can run the entire length of the pontoon, under the middle of the pontoon and can be attached with a flat band 64 for example every meter to the horizontal canvas part 32' which collects oil. At the rear edge 62, the chute is closed, and the chute can be kept open by weighting it at the bottom edge with a lead line threaded through a raceway.

The pontoons 14, 16 can be kept constant under a small overpressure (for example 1.1 bar) via an air hose from an air outlet on board or a compressor (not shown). This is simplified by the fact that the asymmetric construction means that the rear part of the system is always close to the stern of the towing vessel 12.

The forces that affect the system (waves, current, towing speed, towing resistance) are taken up by the fact that flat straps with great strength are sewn/welded into the canvas surfaces. The rope network may comprise ropes of high molecular weight polyethylene (eg Dyneema, Spectra) which are stronger than stainless steel in the same dimension.

The pump well 20 (which can have a weight of approx. 1 tonne) can be towed in the direction of travel using a separately dimensioned rope made of, for example, Dyneema, where the rope can be attached to a separate rope bracket 80. The forces that affect the system do not stress canvas surfaces or other weak parts of the construction, but is taken up through flat straps with high breaking strength and ropes that may have an oversized breaking strength.

Figures 10 and 11 show the pump well in more detail. The pump well 20 can in an exemplary embodiment be a well 72 in the form of, for example, a pipe with a diameter of 3 m and a depth of 1.5 m. The "river" along the pontoon 14 flows unbroken straight into the pump well, and the water, which is heavier than the oil , is displaced through the open bottom 74, while the oil floats on the surface and can be pumped on board the towing vessel through a hose 54 via a hydraulic pump 76.

The inlet to the pump well 20 can consist of a horizontal slot 70 positioned underwater, preferably flush with the horizontal lower part 32, 32' of the canvas. The well 72 itself can, apart from the inlet, be surrounded by a float collar (not shown) which can be approx. 1 m high and 1 m wide. The pump sink in the middle can be covered by a removable cover (not shown) which, together with the lower part 32. 32' of the canvas, forms a closed space above the pump well pipe and the transition between the pontoon system and the pump well system. The pump well system can be made of aluminium, and cavities in the float collar and pontoon adapters can be filled with polyurethane foam.

An adapter can be screwed onto the system as a terminal for the second pontoon. Otherwise, the systems are the same. This means that you can switch between the two systems according to weather conditions and oil type. In bad weather, the topongtong system will probably be best because waves are dampened and the intake depth is kept constant. If the oil is thick (e.g. heavy oil or highly waxy types of oil), the single pontoon system would probably be best as lumps etc. would be able to be collected and pumped.

The pump 76 can be a hydraulically driven pump, which can require approximately 90-130 l/m of hydraulic oil quantity which can be delivered via a hose 82, withstand a maximum pressure of approx. 200 Bar and can deliver 1,600 tonnes of water/hour at a height of 5 m. The suction nozzle 78 for the pump can be placed approx. 10 cm below the liquid surface. Oil and water are pumped to tanks in vessel 12, and water is separated by gravity and pumped overboard again.

If a vessel without tanks is used, the oil/water mixture can be pumped into tow sacks made of tarpaulin surrounded by a network of flat straps that absorb the forces (not shown). The tow sacks can be filled by inserting a hose from the pump in the pump well via a three-way valve on the stern deck of the vessel far into the sacks. It may also be relevant to let the pontoon systems end directly in the collection bag if the system is used for small or poorly equipped vessels

At the front end of these bags there may be an outlet on the underside where water can escape. The outlet spigot is made of tarpaulin, and can be closed from the vessel by tightening a cord that is threaded through a passageway at the end of the outlet spigot. When the bag is full of oil (the water has been forced out through the drain plug) it can be released and anchored with an anchor line with a marking buoy. Before it is released, a new bag is threaded onto a parallel hose, and the three-way valve directs the fluid flow into this bag. Before the bag is released, it is closed by tightening a string threaded through a running passage in the filling spout, and this filling spout is weighted so that it sinks under the bag and does not leak. The bag is held in position by the vessel by a line from the flat strap network moored in a bollard. This can be attached to the tow rope and buoy, which are released together when the bag is filled.

The systems are scalable and can be built for vessels from, for example, 10 m to 200 m. They do not require much towing power, and a 10 m vessel with an engine power of approx. 100 hp can tow such a system with 4 knots. For vessels without available hydraulic power, a diesel-powered hydraulic unit can be supplied.

Claims (12)

1. Collection system for chemical spills, comprising an elongate, projecting grab arm equipped with at least one pontoon (14) adapted to be towed by a vessel, wherein contaminant floating on or in a water surface (50) is caused to flow along the pontoon ( 14) and to a collection device (20) for collecting the chemical spill, and where the at least one pontoon (14) is equipped with a cloth (30, 30') which lies around the pontoon (14), characterized in that - the cloth has a lower part (32, 32') which protrudes from the pontoon below the water surface (50) to delimit a surface layer of chemical and water from underlying water masses, and to guide the chemical to the collection device (20), and - that a rope network (18) is connected with the canvas (30, 30') to pull the canvas (30, 30') and the pontoon (14) in the direction of travel. 2. System in accordance with claim 1, characterized in that the canvas (30) is arranged around the pontoon (14), in which the lower part (32) is designed as a skirt that protrudes mainly horizontally below the water surface (50), and that an upper part (34) of the canvas projects mainly horizontally from the pontoon above the water surface (50) and is arranged to function as a splash screen. 3. System in accordance with claim 1, characterized in that the rope network (18) or the lower part (32) of the fabric (30) is equipped with a lead plumb (42) designed to regulate the depth of the fabric (30) depending on the rope speed. 4. System in accordance with claim 1, characterized in that the catch arm (10) is equipped with a second pontoon (16), in which the second pontoon (16) is arranged in front of said at least one pontoon (14). 5. System in accordance with claim 4, characterized in that the canvas (30') is arranged around both pontoons (14, 16) so that an at least partially closed space is formed between the pontoons, and that the lower part (32') of the cloth is equipped with several slit openings (40) to delimit the surface layer of chemicals and water from underlying bodies of water. 6. System in accordance with claim 5, characterized in that the lower part (32') of the canvas, in an area between the slot openings (40) and the pontoon (14), is equipped with lead weights (42'). 7. System in accordance with claim 6, characterized in that several outlet openings (44) for surplus water are arranged in an area adjacent to the lead solder (42'). 8. System in accordance with claim 5, characterized in that a number of straps (36) are arranged around one or both pontoons (14, 16), and which are connected to the rope network (18). 9. System in accordance with claim 5, characterized in that a number of straps (38, 38') run between the first and second pontoons (14, 16), and which are connected to the rope network (18). 10. System in accordance with claim 2 or 5, characterized in that a rear part (32a) of the lower part (32') of the canvas is attached in front of the rear pontoon (14), in an area above the water surface (50). 11. System in accordance with claim 10, characterized in that a canvas chute (60) is arranged under the pontoon (14), where the canvas chute (60) is closed at the rear edge (62) and at least partially open at the front edge (64), and that the canvas chute (60) at the front (64) is attached to the lower part (32'). 12. System in accordance with claim 1, characterized in that the collection device is a pump well (20) designed to receive chemical and water flowing inward along the catch arm (10), and to pump mainly chemical to the vessel or a tow bag.