GB2233573A - Oil recovery - Google Patents

Abstract

Floating oil and solids are picked up by mesh scoops 11, 13 on a rotating drum 3, the scoops being hinged back by blades 31, 35 to discharge their contents and then cleaned by brush 37. Scoops 13 are larger than scoops 11 and collect solid debris which is received in hopper 33, while scoops 11 collect oil which is discharged by screw pump 41. The drum is pivotally mounted on a catamaran whose hulls carry hydrofoils which deflect oil towards the surface. They also carry outwardly extending booms in the form of endless perforate belts which are driven so that they have no effective forward motion in the water (Figs 4, 5). The oil-water mixture from pump 41 is fed to a settling tank via a filter, cleaned by a rotary brush, to remove solids (Fig. 6). <IMAGE>

Description

OII RECOVERY This invention relates to the recovery of floating oil and debris from water.

Numerous oil recovery devices and methods have been proposed, including for example the use of booms and skimmers, However, these all suffer from more or 3ess serious disadvantages. In particular, they do not satisfy the following desirab]e criteria, (a) A skimmer should be able to recover oil which has heen weathered and whose viscosity may vary ouer a wide range (including emulsified and solidified oils) (b) Recoverability stiou]d be independent of the thickness of the oil layer and the amount of debris present.

(c) The oi] should not be allowed to run off the body of the recovery device.

(d) Tubes and meshes used in the recovery device should not clog.

(e) The recovery device should he capable of following the wave and swell patterns, and it should not be adversely affected by strong currents, (f) The skimmer should have a mechanisln with which to maximize its oi] encounter-width i,e, it should not rely on static booms to concentrate the oil ayer.

(g) The recovery device should not cause turbulence which might disperse oil away frown the skimmer, (h) The recovery device should be able to retain the recovered oil and debris without significant loss through entrainnient in the current, (i) The amount of water taken in hy the recovery device should he as little as possible, (j) The skimmer should be mechanically simple and robust, so that the prohahility of uechanicctl failure is Ininimised, Furthermore, operation of the system should be uncomplicated, (k) Deployment of the recovery device(s) should be simple and workable at sea.

(1) The system should also be capable of other applications, such as the co3lection of floating rubbish, when it is not being used for oil-recovery, Clearly, this would make the system commercially more attractive, The present invention, in one aspect, resides in a device for recovering floating matter from a body of water, comprising a movable carrier, at least one scoop on the carrier, and means for moving the carrier whereby the scoop is moved in a path which, in use, intersects the surface on which said matter floats, the scoop being perforated to allow egress of water while collecting and retaining floating matter.

For minimal disturbance of the flow, the carrier preferably has a closed continuous surface, and most preferably it is a cylindrical drum.

Also to minimise flow disturbance, the carrier is preferably buoyant and mounted for movement up and down in response to waves and swell.

The invention in another aspect provides a device for recovering floating matter from a body of water, said device and water moving relative to one another in operation of the device, said device comprising at least one boom angled forwards in the direction of relative motion of the device in the water for deflecting floating matter, the said boom comprising an endless moving belt apertured to allow passage of water through the belt while deflecting floating matter.

Preferably the boom and/or the belt is buoyant.

The use of perforated or apertured members enables water to pass through during the recovery operation, thereby ninimising turbulence and breakup of oil, and also enhancing oil concentration, In yet another aspect the invention provides a device for recovering floating flatter from a body of water, said device and water moving relative to one another in operation of the device, said device comprising at least one mesh Member arranged to retain floating matter and transfer it from one place to another while allowing passage of water through the mesh, and means for substantially continuously or repeatedly cleaning the mesh member of entrapped Inatter during operation.

The invention further provides a device for recovering solid floating matter from a body of water, comprising movable lifting means arranged to lift solid floating matter from the water, and extraction means for removing lifted solid matter from the lifting means.

The invention further provides a device for recovering oil and solid floating matter from a body of water, comprising means for mechanically separating solid matter froin other recovered matter.

The invention further provides a device for recovering floating matter from a body of water, said device and water moving relative to one another in operation of the device, said device comprising at least one hydrofoil blade forwardly disposed and angled upwards and rearwards, for forming a concentrated surface layer of said matter.

The invention further provides a device for separating solid debris froin a mixture of solid debris and liquid, comprising a closed vessel for receiving solid debris and hauing in an upper region an inlet and an outlet, a filter adjacent the inlet and above a liquid-receiving space, neans for feeding the mixture downwards onto the filter whereby liquid passes down through the filter retaining solid debris on the filter; and means for transferring retained debris from the filter into the said receiving vessel, displacing liquid from the vessel through the outlet.

The invention further provides a device for separating solid matter from a mixture thereof with oil and water comprising a housing defining a solids-receiving chamber and an entry chamber higher than and to one side of the solids receiving chamber, a filter forming a floor of the entry chamber with a liquids-receiving space below the filter, a restricted passage interconnecting the entry chamber and the solids-receiving chamber adjacent a side of the filter whereby in operation an oil/water interface can be defined between the entry chamber and the solids-receiving chamber, and means for transferring into the solids-receving chamber solid matter retained on the filter thereby displacing water, in operation, from said chamber through said passage.

The invention further provides a method of separating solid matter from a mixture thereof with oil and water, comprising supplying said mixture onto an upper surface of a horizontal or sloping filter whereby oil and water pass downwards through the filter and solid matter is retained on the filter, removing the retained solid matter from the filter to a solids-receiving chamber through an aperture. in an upper region of sad chamber and communicating with the space above the filter, said chamber containing water, and defining an oil/water interface at or adjacent said aperture, whereby oil will not enter said chamber but water may be displaced therefrom.

The present invention will be further described with reference to the accompanying drawings, in which: Figure 1 is a schematic plan view of an oil recovery device of a twin-hull skimmer Figure 2 shows the oil recovery device in side view and partly in longitudinal section Figure. 3 shows schematically, in plan view, oil-collecting booins attached to the skimmer Figure 4 shows the construction of a single collecting boom Figure 5 shows details of a belt forining part of the boom, and Figure 6 shows schematically apparatus for separating solid debris from oil and water.

Figures 1 and 2 illustrate schematically, in plan view and in longitudinal section, oil recovery means of a skimmer.

The skimmer is a twin-hulled vessel, with hulls 1 as shown in Figure 1. The hulls are interconnected by booms or a deck. The vessel may be self-propelled, but is preferably propelled by a separate pusher at the stern.

In the gap between the hulls is an oil recovery devi ce of which the primary component is a drum 3 rotatable about a horizontal axis, The drum is buoyant and rests on the surface 23 of the water between the hulls. It is connected to the hulls by a pair of parallel arms 5 which are generally horizontal, each with its rear end connected to the associated hull by a pivot 7 and its forward end connected to the rot -able drum by a shaft or axle 9, Because of its mounting on the pivoted arms 5, the drum can rise and fall relative to the hulls of the skimmer. In operation, the drum rests on the water as shown in Figure 2, When not in use, the drum can be raised clear of the water for example by ropes or chains attached to the arms 5 and connected to a suitable winding mechanism or other lifting and lowering means.

Scoops 11, 13 are mounted on the drum, distributed around its periphery and each extending longitudinally.

Each scoop is made of a mesh material, with a mesh si7e such as to permit passage of water but not of oil and debris.

Each scoop is hinged to the drum and is spring loaded so that it is normally in the operative position shown in Figure 2 but can fold back against the surface of the druin to release oil and debris collected in the scoop.

In operation, the drum is rotated while in contact with the water. It may be rotated for example by a driving chain or belt generally parallel to the supporting arms 5, or by a motor mounted in the drum or on the forward end of an arm. The rotation of the drum can be clockwise or anticlockwise in Figure 2, it is clockwise in the illustrated embodiment, The scoops are connected to the drum by hinges 15, which may be spring-loaded hinges, or plain hinges with separate springs provided to hold the scoops in operating position. The drum surface itself will usually be smooth, and the drum is sealed to provide buoyancy and to prevent oil and debris collecting in its interior.

The scoops may be of different sizes. Figure 2 shows smaller scoops 11 intended primarily for collecting oil, and a larger scoop 13 capable of collecting larger pieces of debris. Respective scoops may have nesh of different dimensions, to facilitate the collection of oil over a wide range of viscosities, including weathered oil, The dimensions of the drum and scoops, and the rate and direction of rotation of the drum, may uary widely according to the intended application of the skimmer.

By way of example only, the drum may haue a diameter of the order of 2 meters and a length of the order of 3 meters or more, and a rate of rotation of the order of 10 rpm. The gap y between the drum surface and the edge 4S of the deflector plate 31 is, typically, about 30cin, and the mouth of the larger scoop 13 may typically have a width of the order of 45cm.

In operation, the drum with its scoops floats on the surface. of the water at a predetermined level, and is rotated while the skimmer aduances, for example at a speed of the order of 1/2 to lm/sec, In Figure 2 the direction of rotation is indicated by the arrow 17 and the direction of flow of the water relative to the skimmer by the arrow 19; that is to say, the skimmer is advancing towards the left in Figure 2.

Oil and debris adhere to the surface of the druin as shown at 21 and are raised away from the water surface 23. Because of the relative horizontal motion of the drum and water, oil and debris build up in the region 25 immediately below and forward of the drum surface, As the drum rotates, oil and debris can be recovered by scooping from the region 27 swept out in the water by the scoops, for example as shown at 29. Inevitably some of the oil will break up into droplets which may escape by being entrained in the water flow past the recovery device.However such oil, even when entrained to a certain depth, can nevertheless be scooped up, because the scoops at their lowest position are below and abaft the position where the oil first encounters the recovery device and tends to break up.

The scoops containing oil and debris move upwards with the drum, clear of the water surface. adjacent the surface of the drum on its decsending side, is a deflector plate 31 which has an upper edge 45 spaced from the. surface of the drum by a predetermined clearance y and which slopes downwards away from this edge and away from the drum, to a receiving trough or hopper 33.

Below the deflector plate 31, that is to say, following it in the direction of rotation of the druin, are a first scraper 35 and a second scraper 37, each pivotable about a horizontal axis parallel to the surface of the druin and spring-biased into contact with the drum surface.

As the drum rotates, debris which is too large to pass through the gap between the deflector plate 31 and the drum, in particular larger pieces of debris picked up by the larger scoop 13, is collected by the deflector plate and slides down into the hopper 33. The gap between the deflector plate and drum is wide enough to permit passage of the smaller scoops t1 but not of the larger scoop 13.

As the larger scoop 13 encounters the deflector plate it folds backwards about its hinge, until it can pass clear under the deflector plate, whereafter its resilient bias snaps it back into the illustrated operating position, The first scraper 35 is in the form of a blade, and scrapes off oil and small debris from the surface of the drum s the smaller scoops 11 encounter its edge, they are folded back against their spring bias and the scraper 35 removes the oil and small debris trapped in the scoops 11.

The scoops may be folded back by impact with the plate 31 and scraper 35, or a mechanism may be provided for folding the scoops back immediately before they encounter the plate or scraper, to reduce wear, The second scraper 37 forms a brush, which brushes the snesh or screen of the folded-back scoop and thereby cleans and unclogs the mesh and removes remaining traces of oil and debris, The larger scoop 13 is cleaned in the same way.

After passing the second scraper 37, the scoop is snapped back into its operating position by its spring bias Oil and debris removed by the scrapers 35, 37 fall onto a flexible connecting sheet 39, along which they pass to the inlet of a vertical Archimedean screw pump 41 which is driven to lift the oil and small debris quickly.

This pump is fixed to the skimmer vessel. The rest of the components of the recovery device may be supported, with the druin, by the arms 5, or alternatively, may be supported directly by the skimmer hulls. Mounting the components on the arins 5 has the aduantage that the positions of the components relative to the drum 3 is not affected by relative vertical movement of the drum in response to waues or swell. Moment of the scrapers relative to the pump, in such an arrangement, is accommodated by the flexible connecting sheet 39 or other suitable flexible connection, However, mounting the plate 31 and trough 33 on the arms 5 may be disadvantageous because of the weight and mass of these components when loaded with solid debris, and accordingly it is desirable to mount them on the hulls.

In this case, the plate 31 must be so mounted, or provided with a flexible connection, that the gap y remains constant in the presence of relative vertical motion of the hulls and drum.

Ruffers may be provided to limit the up and down oscillation of the recovery device when in contact with the water surface, n de-emulsifying agent may be supplied to the screw pump. Preferably the de-emulsifying agent is supplied to the lower region of the pump for example as shown at 43, so that the action of the pump itself mixes the de-emulsifying agent into the recovered material to effect separation of the oil/water emulsion.

The recovered material is pumped by the screw pump to storage means. The storage may be provided on the skimmer but this is undesirable because it increases size. and mass of the skimmer. Preferably therefore the storage means are provided on a separate vessel, for example a lighter or a pusher vessel used to propel the skimmer The recouered material may be fed to the storage means by way of a hose connection and a fast-flow filter system.

For rotating the drum, a small electric Inotor may be provided, however a mechanical drive or hydraulic motor is preferable. The druin drive should prouide for steady rotation of the drum, preferably with variability of the rate of rotation. If the skimmer is propelled by a separate vessel, power for the drum drive can be provided from the propelling vessel.

The described oil recovery device has a number of important advantages. The use of a vertically movable buoyant drum enables the primary element of the recovery device to follow waue and swell motion and therefore to maintain a substantially constant depth of immersion and surface of contact with the layer of oil and debris, Recovery conditions are therefore near-constant, and disturbance of the oil/debris layer is minimised. 4 cylindrical drum with a smooth solid surface provides the least disturbance of flow and therefore the best recovery conditions, Because the scoops are of mesh material through which water can flow, resistance to movement of the scoops through the water is reduced, and flow disturbance is also reduced, thereby reducing any tendancy of the recovery device to break up the layer of oil and debris with consequent loss of oil and debris by entrainment in the water flow. The described device produces less turbulence than a static filter mesh, and less wave resistance or bow wave formation than a belt-type recovery device would.

The low and substantially constant volume of contact between the druin and the water reduces turbulence and therefore reduces dispersal of oil and loss of oil by entrainment in the water flow.

A further advantage of the described device is that it provides for continuous recovery and removal of solid debris, which again reduces disturbance of the oil layer and enhances the efficiency of oil collection.

Hitherto, debris has not been continuously recovered during operation, but has been allowed tn accumulate on the water surface while oil is recovered, Q further advantage of the described arrangement of drum, scoops, and removal elements, is that the oil and debris are carried over the top of the drum before being detached and removed. fis a result, the oil and debris can be delivered onto removal elements from above, minimising the risk that oil and debris may fall back into the water, The use of scoops of mesh material, apart from reducing turbulence in the water, also reduces the amount of water picked up by the recovery device and therefore enables the oil to be subsequently separated more efficiently with smaller separating means and less use of chemicals.

It will be seen that the device is mechanically simple and robust, easy to use and easy to deploy at sea.

The provision of means for continuously cleaning the mesh of the scoops increases efficiency and also increases the length of time between maintenance operations, In order to concentrate the layer of oil and debris towards the water surface, and thereby increase the efficiency of recovery by the drum, one or more submerged hydrofoil blades 51 may be Mounted between the skimmer hulls immediately forward of the drum.

Preferably, there are a plurality of hydrofoil blades at different depths, arranged in a "ladder" either vertically one above another, or in a line sloping upwards and sternwards. The or each hydrofoil blade is positioned obliquely with its trailing edge upwards to direct flow towards the surface, The hydrofoil blades not only concentrate the oil in the surface layer and debris layer but dissipate some of the wave energy and minimise oil dispersal and entrainment in the water flow. The use of a vertical or oblique "ladder" of hydrofoil blades ensures that wav motion and vertical motion of the vessel do not affect the flow of oil over the hydrofoil blades.

Alternatively, one or more hydrofoil blades can be fixed to the arms 5 of the recovery device.

The hydrofoil blade or blades should be so arranged that they can be readily deployed into the water, or raised clear of the water, while the skimmer is at sea.

The. use of hydrofoil blades, and the fact that the scoops dip below the oil layer, make recovery effectively independent of the oil layer thickness and the amount of debris.

To increase. the effective oil-recovery width of the skimmer, it may be provided with one or two booms, extending laterally from one or each hull forward of the oil-recovery device.

Figure 3 shows in plan, by way of example only, two such booms 57 each mounted on the outer side of a respective hull 1 abaft the bow, with yaps or channels 59 in the hulls directly forward of the inboard ends of the booms. Each boom is angled forwards, so that as the skimmer advances, oil and water outside the width of the hulls is deflected by the booms into the space between the hulls and therefore into contact with the oil-recovery device (not shown in Figure 3), Thus it will be evident that the skimmer can, in one pass, sweep out a width of oily water substantially greater than the width over the hulls.

Each boom consists essentially of a moving endless belt. The limbs of the belt are set with their planes substantially vertical, The forward limb 61 moves inwards towards the hull, while the aft limb 63 moves outwards away from the hull. Preferably, the rate of movement of the belt limbs, the angle between the longitudinal direction of the belt and the foward direction of the hull, and the velocity of the skimmer, are so selected that there is no net motion, in the longitudinal direction of the hulls, between any point on the forward limb 61 of the belt and the water. This minimises turbulence at the forward limb 61 and therefore provides for the most effective accumulation and inwards transfer of oily water and debris by the belt.

Preferably, the belt speed and the angle between the belt and the hull are adjustable.

One possible form of boom construction is shown by way of example only in Figure 4. In this Figure, the skimmer hull 1 is shown only schematically.

The l: boom comprises an outrigger arm 65 hinged to the side of the hull by a joint 67 which is capable of allowing the arm to pivot up and down and preferably also fore and aft. At the outboard end of the outrigger arm is a float 69. Adjacent each end of the outrigger arm, a sprocket wheel or pulley 71 is mounted on the underside of the outrigger arm, and the belt passes around these. The belt is driven by any suitable driving means for example an electric or hydraulic motor mounted on the outrigger arin or on the hull.

The outrigger arm is held in position against the thrust of the water due to the motion of the skimmer, by a strut 73 extending between the outrigger arm and the hull. This strut may be provided with means for adjusting the angle of the outrigger arm fore and aft relative to the hull.

Means are provided for lifting the outrigger arm clear of the water, for transit, so that the outrigger arm and belt can be deployed after the skiMnnr has reached its operating position at sea, The joint 67 and the float 69 enable the outrigger arin to rise and fall with the waves so as to minimise variations in the depth to which the belt 61 is immersed. Additionally, the belt itself may be buoyant so that it too can rise and fall with waves.

The belt may have vertical ribs 75 as shown in Figure S, to assist in the longitudinal entrainment of oil and debris by the moving belt. By the movement of the belt, oil and debris are transported inboard to accumulate in the region 77 where the boom adjoins the hull. In this region, one or more scrapers may be provided, mounted for example on the outrigger arm, to separate oil and debris from the moving belt and direct them towards the recovery device.

The belt itself is permeable to water, for example being provided with regularly spaced holes 79, This enables water to pass through the belt while oil and debris are retained against its front surface, This provides a pre-concentration of the oil and debris before it reaches the recovery device, and has the advantages that, because water can pass through the belt and therefore does not have all to pass around or under it, flow conditions at the interface between the belt and the water are relatively smooth, the oil layer is not significantly broken up, and oil recovery is enhanced, the amount of water in the recouered oil/water mixture is reduced, and the water pressure on the belt due to skimmer movement is reduced, As already mentioned, the belt itself Inay be buoyant, for example being made of aerated material or provided with air pockets. It normally floats with a predetermined depth of immersion, the still water level being indicated at 81 in Figure 5.

In one convenient construction the belt consists of segments 83 interconnected so as to allow at least limited flexing of adjacent segments to follow waves and swell. The segments can for example be interconnected through ball and socket joints enabling the belt to pass around the sprocket wheels or pulley, and to flex Up and down. Adjacent segments overlap to provide an effectively continuous belt and eliminate loss of oil or debris between segments.

Because the belt can float, with a substantially constant depth of immersion, water resistance is reduced, and flow disturbance is minimised, reducing breakup and loss of the oil layer, The constant depth ensures essentially constant recovery conditions.

Means are provided for preventing clogging of the apertures in the belt through which water passes. In one arrangement, these apertures, or at least some of them, serve as sprocket holes, which are penetrated by sprocket teeth 85 of the sprocket wheels, simultaneously driving the belt and clearing blocked holes.

Rlternative.ly or in addition, rotating brushes may be provided on one or both sides of the belt to clear accumulated material that might clog the holes, In this case, the holes may differ in size, to recover oil of various degrees of viscosity, It is to be understood that the boon arrangement just described is applicable to skimmers other than that described with reference to Figures 1 and 2, and indeed to other uses. It can be applied to skimmers using any kind of oil and/or debris recovery device, and to monohull as well as to multihull vessels. The booms can be easily fitted to and removed froin hulls, and can for example be retrofitted to existing skimmers.

The described skimmer recovers oil and/or debris at a high rate. To cope with this, a fast-acting separating system is required. Figure 6 shows one possible separating system.

This comprises a housing 91 devided by an internal partition 93 into a discharge chamber 95 for oil and water, and a solids chamber 97 for debris. The chamber 95 is connected to a settling tank for example on the vessel propelling the skimmer. The chamber 97 is closed, except for a relatively small entry aperture 99 in its upper region adjacent the partition 93, but is provided with a pressure relief valve 101.

The pipe 103 leading from the Archimedean screw pump 41 pens into an enlarged region 105 above the discharge chamber 95. The region 105 and the discharge chamber 95 are separated by a filter 107, for example of wire mesh. Prfrahly, this filter slopes so that its edge adjacent the partition 93 is lowest.

4 rotating scraper 109 is in contact with the upper surface of the filter 107 and also projects into the solids chamber 97. It is driven in rotation in any connint way for example. through a shaft 111.

In operation, the mixed oil, water and debris are pumped under pressure into the region 105, within which the pressure decreases because the cross sectional area is increased.

The solids chamber 97 is initially full of water. In operation, oil and water froin the region 105 pass through the filter 107 and thence to a settling tank.

Solid debris remains on the upper surface of the filter, from which it is scraped off and transferred into the solids chamber 97, by the rotating scraper brush 109.

Heavy debris 113 falls to the bottom of the chamber 97, light debris 115 rises to the top, The incoming debris displaces water from the chamber 97 onto the filter 107 from which it passes into the discharge chamber 95, until the chamber 97 becomes so full that the debris has to be removed, for example by opening the chamber or by opening suitably placed outlet valves.

Since oil floats on water, oil will not tend to enter the chamber 97 in significant amounts, and an oil-water interface will form at the entry aperture 99 of the solids chamber 97.

Conveniently, the filter and the discharge chamber are semi-circular in plan to provide for efficient contact between the filter and the scraper brush.

This device provides rapid and effective separation of solid debris from the oil and water, The sloping arrangement of the filter enables gravitation to assist the removal of solid debris from the filter surface into the solids chamber.

The use of a brush as the scraper will keep the filter clean and reduce clogging. fi pair of brushes may be provided on a common shaft, one brush engaging the upper surface of the filter and the other engaging the lower surface of the filter, for more effective cleaning of the filter.

A plurality of filters may be prouided in series, with respective scraper brushes, In this case the filter mesh si2e. will decrease from one filter to the next.

Thus, larder pieces of debris will be removed at the first filter, small debris at subsequent filters. This provides more effective separation of solids from the oil and water and reduces the risk of clogging of the filters. The respective scraper brushes would be mounted on a common driven shaft.

As already mentioned, the skimmer may be propelled by a vessel pushing it from the stern. The advantage of this is that the mass, size and cost of the skimmer are reduced, and the skimmer will encounter the oil and debris first, before the propelling vessel, The oil and debris are therefore in an undisturbed condition when encountered by the skimmer, The pushing vessel can be coupled to the skimmer or the skimmer may be free.

In one convenient arrangement, one or more flexible members extend between and are connected at the ends to sternward portions of the skimmer hulls, and the propelling vessel is placed with its stem between the skimmer hulls and pressing against the flexible members, This provides that the two vessels can move relative to one another vertically but not laterally, and also permits relative roll and pitch movements.

Rollers or fenders may be provided between the hulls of the two vessels to reduce interference and possible damage.

To enable the skimmer to be pushed by a variety of vessels, the flexible members are preferably attached to the skimmer hulls by means of a plurality of bollards on which the ends of the flexible members can be attached selectively to match the shape and size of the bow of the pushing vessel, In addition, a direct connection may be provided between the bow of the pushing vessel and the skimmer hulls, for example by ropes or chains, to hold the vessels securely together, The skimmer may have its own electric, pneumatic or hydraulic power supply, alternatively power may be supplied to the skimmer from the pushing vessel, The various devices described are intended primarily for the recovery of oil from water, but it is to be understood that they can be used for recovering debris in the absence of oil. These devices can therefore be used, for example, in keeping harbours and waterways clear, when not being used to deal with ari oil spillage.

Claims (1)

1, A device for recovering floating matter from a body of water, comprising a movable carrier, at least one scoop on the carrier, and means for moving the carrier whereby the scoop is moved in a path which, in use, intersects the surface on which said matter floats, the scoop being perforated to allow egress of water while collecting and retaining floating matter, 2. S device as claimed in Claim I in which the said carrier presents a closed continuous surface, 3. 5 device as claimed in Claim 2 in which the carrier is a cylindrical drum, 4. A device as claimed in Claim 1, 2 or 3 in which the carrier is buoyant and is mounted for movement up and down in response to waves.

5. 5 device as claimed in any preceding claim in which the scoop is hinged for releasing collected matter.

6, S device as claimed in Claim 5 further including at least one scraper for removing collected matter from said scoop.

7, 5 device as claimed in Claim 6 in which at least one.

scraper comprises a brush for cleaning the perfciration(s) of the scoop.

8. Q device as claimed in any preceding claim in which the scoop is of mesh material.

9, 5 device as claimed in Claim 8 having a plurality of scoops with respective different mesh sizes.

10. 5 device as claimed in any preceding claim having a plurality of scoops of different sizes.

11. X device as claimed in Claim 10 having adjacent the path swept out by the scoops and clear of the water surface, a receiving member spaced from the carrier by more than the. size of at least one smaller scoop and less than the siz of at least one larger scoop, for receiving large solid debris from said larger scoop.

12. X device for recovering floating matter from a body of water, said device and water moving relative to one another in operation of the device, said device comprising at least one boom angled forwards in the direction of relative motion of the device in the water for deflecting floating matter, the said boom comprising an endless moving belt apertured to allow passage of water through the belt while deflecting floating matter.

13. A device as claimed in Claim 12 comprising a movable hull on which the boom is mounted.

14. A device as claimed in Claim 12 or 13 in which the boom is buoyant and is mounted to move up and down with waves and swell, 15, A device as claimed in Claim 12, 13 or 14 in which the belt is buoyant.

16. 5 device as claimed in any of claims 12 to 15 further including means for cleaning the apertures in the belt.

17, A device for recovering floating matter from a body of water, said device and water moving relative to one another in operation of the device, said device comprising at least one mesh member arranged to retain floating matter and transfer it from one place to another while allowing passage of water through the mesh, and means for substantially continuously or repeatedly cleaning the mesh member of entrapped matter during operation.

18. h device as claimed in Claim 17 in which the cleaning means comprise at least one brush.

19. n device for recovering solid floating matter from a body of water, comprising movable lifting means arranged to lift solid floating matter from the water, and extraction means for removing lifted solid matter from the lifting means.

20. R device for recovering oil and solid floating matter from a body of water, comprising means for mechanically separating solid matter from other recovered matter.

21. 4 device for recovering floating matter from a body of water, said device and water moving relative to one another in operation of the device, said device comprising at least one hydrofoil blade forwardly disposed and angled upwards and rearwards, for forming a concentrated surface layer of said matter.

22. n device for separating solid debris from a mixture of solid debris and liquid, comprising a closed vessel for receiving solid debris and having in an upper region an inlet and an outlet; a filter adjacent the inlet and above a liquid-receiving space, means for feeding the mixture downwards onto the filter whereby liquid passes down through the filter retaining solid debris on the filter; and means for transferring retained debris from the filter into the said receiving vessel, displacing liquid from the vessel through the outlet.

23. A device for separating solid matter from a mixture thereof with oil and water comprising a housing defining a solids-raceiving chamber and an entry chamber higher than and to one side of the solids receiving chamber, a filter forming a floor of the entry chamber with a liquids-receiving space below the filter, a restricted passage interconnecting the entry chamber and the solids-receiving chamber adjacent a side of the filter whereby in operation an oil/water interface can be defined between the entry chamber and the solids-receiving chamber, and means for transferring into the solids-receiving chamber solid matter retained on the filter thereby displacing water, in operation, from said chamber through said passage.

24. A device for separating solids and liquids substantially as herein described with reference to Figures 6 of the accompanying drawings.

25. Devices for recovering floating matter, substantially as herein described with reference to any one or more. of Figures 1 to 5 of the accompanying drawings.

26. 5 method of separating solid matter from a mixture thereof with oil and water, comprising supplying said mixture onto an upper surface of a horizontal or sloping filter whereby oil and water pass downwards through the filter and solid matter is retained on the filter, removing the retained solid matter from the filter to a solids-receiving chamber through an aperture in an upper region of said chamber ad communicating with the space above the filter, said chamber containing water, and defining an oil/water interface at or adjacent said aperture, whereby oil will not enter said chamber but water may be displaced therefrom,