GB2182260A - Scavenging vessel - Google Patents

Abstract

A vessel for collecting floating oil from open water comprises twin hulls, connected together in catamaran fashion, and elongated openings 8 in the inward-facing sides of the hulls into which floating oil is directed by means 7 as the vessel moves forward. Means 7 may comprise two doors, hinged to the hulls and movable to close the openings 8. In the open position, the doors 7 rest against stops depending from the central superstructure. Alternatively means corresponding to doors 7 may descend vertically from the superstructure to direct the oil into openings 8. Additional openings, with downwardly rotatable diverting means, may be arranged towards the stern on each hull. Each hull contains settling tanks to separate the oil from entrained water. <IMAGE>

Description

SPECIFICATION Watercraftforthe collection and possible recovery of pollutant liquids floating on water surfaces This invention relates to newwatercraftforthe collection and possible recovery of pollutant liquids floating on water surfaces.

The problem of water pollution, and in particular sea pollution, by liquid hydrocarbons accidentally leaking from transporting ships or pipelines is one which is always present and as yet has not been satisfactorily solved.

Cu rrently, the most widely used depolluting means are chemical meanswhichemulsifyanddis- perse the hydrocarbon layers floating on the water.

However, chemical means are never desirable from an ecologicai viewpoint in that they obviously load the waterwith furtherforeign substances which are often harmful to marinefaunaandflora.

On the whole, mechanical means for removing poll uta nt layers fl oati ng on water a re therefore to be preferred.

Of the various types of mechan ical means proposed, those which are of particular interest are watercraft in the form of boats based on the catamaran.

In the past,- systems ofthefull frontal opening type applied to hulls based on the catamaran have been constructed. These constructions have the drawback of being influenced by the sea conditions and thus not being able to effectively collect the entire polluted water surface ahead.

Other systems use the principle of collecting the oily surface deposits by conveying them upwards by various techniques using systems involving constructionally more complicated keels and the corresponding watercraftforcarrying them.

However, of these types of boat some have many practical drawbacks, whereas others more sophisticated have certain difficulties in their construction and operation, among these latterthe need to use dry docks for cleaning the collection systems.

In accordance with the present invention, we have now conceived a newwatercraft which enablesfloat- ing layers of liquid pollutantsto be collected, elim inatedand possibly recovered from the watersur- face, without the drawbacks associated with known depolluting watercraft.

The new depolluting craft is essentially characterised by having its interception system provided on the inner lateral surfaces ofthe hulls of a catamaran.

A catamaran is known to consist of two lateral hulls and a central structure which serves as a stiffener and formsthe inhabitable our control part ofthe craft.

This craft has the characteristic of being faster than the conventional single-hull craft, by presenting a lower resistance to forward movement.

In contrast to the classical construction, these hulls can be used forvarying the attitude of the craft by flooding them.

There is thus the great advantage of providing a collection channel between the lateral hulls, topped by the central structure.

Such a construction has been used in the past by either providing it with a frontal collection opening or equipping it with a central keel designed to house dif ferentcollection systems.

Thusthe inletflowfrom the polluted watersurface has upto now been onlyeitherfrontal orconveyed towards the lower surface of the central keel.

In the present invention, the pollutant liquid layers enter through lateral apertures provided in the inner surfacesofthelateral hulls.

The operational stages can be summarized as follows: Thewatercraft moves into the polluted zone with its decantation tanks empty, and with a degree of im mersion such that only the I ateral hullsareim- mersed.

When in the zone of operation, the decantation tanks are filled with waterto cause the craft to attain a displacement such that the central keel part also remains immersed in water, so forming the aforesaid collection channel.

At a suitable speed of forward movement, depending on various external factors such as the extent of the pollution orthe conditions of the sea orwatersur- face in general, a certain surface liquid layer composed of water and oily residues is withdrawn through suitable apertures in the inner side of the lat- eral hulls.

This mixture is led into the hulls through a structural reservoirandfrom here through one or more pipes into the decantation tanks.

The pollutant liquid is separated from the water in the decantation tanks.

One or more discharge pumps maintain flow through the hulls by withdrawing a quantity of water from the base of the decantation tanks equal to the quantity of mixture composed of oily residues and water which is continuously taken on board as the craft moves forward. As the withdrawal of water from the bottom ofthe tanks continues, an increasing quantity of pollutant liquid accumulates until the tanks are completely full.

When the decantation tanks are completely full of pollutant liquid, this is transferred to storage tanks on land orto other service ships, thus making the craft ready for a new operating cycle.

The characteristics ofthe present invention will be more apparent from the description given hereinafter of a preferred embodiment of a depolluting watercraft according to the invention with reference to the drawings in which the same reference numerals are used for indicating identical parts of the device.

its representation is purely indicative and nonlimiting.

Figure 1 shows a catamaran,which by virtue of its known constructional characteristics enables a col lection channel to beformed betweenthelateral hulls 1, bounded upperly by the connection structure 2 and thus compelling a large surface area of liquid layers, as determined by the dimensions of the craft, to enter the decantation tanks 3 through suitable lateral apertures.

Figure2 shows how as the craft moves forward at suitable speed, depending on various external fac torssuch astheextentofpollution ortheconditions ofthe sea or water surface in general, a certain sur face liquid layer composed of water and oily residues is withdrawn through suitable apertures 8 disposed in the innerside ofthe lateral hulls 1.

Said mixture is led into the hulls through a structural reservoir4, and from here into the decantation tanks3through a pipe 5, as shown in Figure 1.

Figure3showsthe device in its closed configuration, ie in its non-operating state.

Figure 4shows the cycle undergone by the water to be depolluted. The pollutant liquid is separated from the water in the decantation tanks 3.

One or more discharge pumps 6 maintain flow through the hulls by withdrawing a quantity of water from the bottom of the decantation tanks 3 equal to the quantity of mixture, formed from oily residues and water, which is taken on board continuously dur ing the forward movement ofthe craft by the frontal reservoir 4.

As waterwithdrawal from the lower part of the tanks 3 continues, an increasingly greater quantity of poliutant liquid accumulates until these tanks are completely full.

When the decantation tanks 3 are completelyfilled with pollutant liquid, this is transferred to storage tanks on land orto other service ships, thus making the craft readyfora newoperatingcycle.

As shown in Figure 5, the geometry ofthe lateral hulls 1 is such as tofacilitate entry ofthe greatest possible quantityof poliutant liquid in thatasthedis- tance between the walls of the so-called collection channel progressively decreases in the bow end, there is a consequent thickening of the oily layer.

Figure 6 shows the pickup system for the surface water according to the present invention, this consisting essentially of mobile conveyors 7 for the polluted surface layers, and apertures 8 in the lateral hulls in the bow zone.

The conveyors 7 consist oftwo structural elements of suitable vertical dimensions having the same profile as the inner walls of the lateral hulls 1 and being hinged to these hulls. This geometry has the double purpose of allowing water, when they are open, to flow th rough the apertures 8 with a flow as little turbulent as possible and thuswith fairly reguiar fluid threads as shown diagrammatically in Figure 2.

Afurther purpose of the conveyors is to restore the geometrical continuity of the innerwalls of the lateral hulls 1 when they are closed to thus prevent damaging turbulence during transfer navigation, especially withthecraftfull (Figure7).

To preventsternward seepage ofthe polluted surface layer, iethat richest in oil products, the conveyors 7 when in their open position rest against two elements 9 shown in Figure 7which havetheirsame curvature, they being disposed below the central keel 2 and provided with a rubber contacting surface.

As shown in Figure 8, suitableflexible seal el- ements 11 can be disposed in correspondence with the hinges 10 of the conveyors 7, in orderto increase the collection efficiencyofthewatercraft.

The conveyors7 extend verticallyto a height such asto prevent as far as possible any passage ofthe oily surface layers towards the stern, and instead to convey them into the lateral hulls 1 through the apertures 8. Said conveyors 7 can also be configured with an L-shaped vertical section as shown in Figure 9, in order to as far as possible prevent any escape ofthe pollutant liquid towards the stern.

Such a geometry obviously requires the compartments housing the conveyors 7 in the lateral hulls 1 to have a different profile, as shown in Figure 10.

The apertures 8 are of veryelongated rectangular shape to allow mainly only the surface layers richest in oil residuestoenter.

These apertures are provided with removable filter grids, not shown in the figures, to exclude any solid floating materials such as plastic bags, cans and other bulky materials.

The mixture of water and oily residues enters the decantation tanks 3 by way of a structural reservoir4 and two or more pipes 5.

The numberof pipes 5 is afunction ofthedimensions of the craft. These pipes are fitted with a shut-offvalve 12 for adjusting the inlet liquid throughput.

The liquid formed from the mixture of oily residues and water enters the craft and follows a path which results in pressure drops considerably less than those arising in similar vessels, and in particular once inside the craft it is subjectto lesserturbulence, so facilitating separation of the components.

Afurther advantage of the craft according to the invention is the presence ofthe structural reservoirs 4disposed downstream ofthe apertures 8to allow, by way of suitable sealed apertures 13, complete inspection ofthe apertures 8 and their cleaning maintenance, with consequent elimination of the risks due to corrosion, with the added facility of being able to clean the entry apertures 8 and to remove any obstruction by means of a counter-currentwash system by suitably using the discharge pump 6 with a bypass valve system.

The operational efficiency ofthe watercraftfitted with the aforesaid system or device can be varied and optimised, according to external factors, bysimu Itaneously or separately adjusting the speed offor- ward movement, adjusting the shut-off valves 12, and adjusting the discharge pump throughput.

Furthermore, in order to collect the greatest possible quantity of oily residues when the liquid surface is particularly agitated, supplementary water pickups, again based on the same device, can be arranged at the stern end in the innerwalls of the lateral hulls 1 using a system of conveyors 14 which do not open in the manner of a compass but instead can be rotated downwards in a vertical plane.

This embodiment is shown in Figure 11.

In the case of watercraft greater than a certain size, both the bow-end hinged conveyors of Figure 2 and the stern-end hinged conveyors 14 of Figure 11 can be replaced by others which moveverticallyinto a totally contained position within guides disposed inside the central keel 2. This system is not shown in the figures but formes an integral partofthe invention.

With this system there is the advantage of height adjustment, when in operation, as a function ofthe conditions ofthe polluted liquid surface.

In addition, by suitable curvature their shape can be made to optimise the flow of liquid to be conveyed into the lateral hulls.

This curvature is not dependent on the shape ofthe hull.

The aforesaid device can be used both on small watercraft, for which an embodiment comprising lateral hulls 1 which are asymmetrical abouttheirplane of symmetry as shown in Figure 12 is advantageous in order to increase the width of the intake face of the watercraft, and on large watercraft in which the hulls can be symmetrical, given the convenience of operating with floating lines 1 5towed by auxiliary motor boats 16 as shown in Figure 13.

With respect to craft of the prior art, the advantages ofthe invention described and illustrated heretofore can be summarised as follows: - inspectionability of the pickup device, - facility for cou nter-current washi ng ofthe pickup device by its own means, -abilityto workon the devicefor repairorcleaning, without the need to put the craft into dry dock, - considerable constructional simplicity.

Claims (13)

1. A watercraft of the catamaran type for dep- olluting fresh or salt water surfaces containing floating oily liquids or suspended surface emulsions, by collecting surface portions canalised between the hulls of the craft and conveyed by conveyors through suitable apertures, characterised in that said apertures are disposed towards the bow in the inner lateral surfaces of the hulls and are made operational by opening conveyors which are hinged to said surfaces and when open restagainstcounteracting members applied to the underside of the central keel and acting as a stop.

2. A depolluting watercraftas claimed in claim 1, wherein the pollutant liquid collection apertures extend into the reservoir-equipped hulls by way ofan inlet protection grid and multiple delivery pipes intercepted by valves for the purpose of regulating the inletflow.

3. A depolluting watercraft as claimed in claims 1 and 2, wherein the pollutant liquid collection apertures are closed on termination of operation by rearwardly hinged conveyors which perfectly mate with and restore the continuity ofthe inner surface of the hulls, they being operated by mechanical or hydraulic devices.

4. A depolluting watercraftas claimed in claims 1, 2 and 3, wherein the conveyor hinge is protected by a continuous rubber surface applied atoneendtothe conveyor and at its other end to the inner surface of the reservoir in orderto facilitate dynamic inlet flow and prevent seepage of pollutant liquids towards the stern.

5. Adepollutingwatercraftasclaimed in claims 1 and 2, wherein the collection aperture is closed by non-planeconveyorsofLprofileforthe purpose of preventing seepage from below towards the stern when open, when closed they restoring continuity of the inner surface of the hulls onlyforthethree upper sides of the aperture, said conveyors being operated by mechanical or hydraulic devices.

6. A depolluting watercraft as claimed in claims 1, 2, 3 and 4,wherein supplementarycollection aper- tures are applied towards the stern in addition to those towards the bow, and again operate on the inner lateral surfaces of the watercraft hulls in order to collect any pollutant residues which have escaped the system disposed towards the bow.

7. Adepolluting watercraft as claimed in claims 1, 2,3,4 and 6, wherein those collection apertures disposed towards the stern in the hulls are made operational by rotating a rigid pair of suitably profiled conveyors hinged upperly and rotating about a horizontal axis, they being operated by a mechanical or hydraulic device.

8. A watercraft of the catamaran type for dep- olluting fresh or salt water surfaces containing floating oily liquids or suspended surface emulsions, by collecting surface portions canalised between the hulls of the craft and conveyed by conveyors through suitable apertures, characterised in that said apertures are disposed towards the bow in the inner lateral surfaces ofthe hulls and are made operational by opening vertically-positioned descending conveyors of a profile suitable for the purpose and operated by hydraulic or mechanical devices, said conveyors being housed in the central structure between the hulls.

9. A depolluting watercraft as claimed in claim 8, wherein supplementary collection apertures are disposed in the inner lateral surfaces ofthe hulls tow- ards the stern and are made operational by vertically lowering conveyors of profile suitable for the purpose, said conveyors being operated by mechanical or hydraulic devices.

10. A depolluting watercraft as claimed in claims 1 to 9, wherein the grids on the collection apertures disposed to the front of the reservoirs are cleaned by counter-currentwashing performed in any manner.

11. Adepolluting watercraftas claimed in claims 1 to 10, wherein the reservoirs and collection apertures are inspected and maintained by way of a sealed inspection aperture bolted and/or hinged to the top of the reservoir.

12. A depolluting watercraftas claimed in claims 1 to 1 1,wherein the delivery pipes are more than one in number and extend from the reservoir, theirthroughput being adjustable by shut-off valves operated in any manner.

13. A depolluting watercraft substantially as herein described with reference to the accompanying drawings.