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(11) | EP 0 113 188 A1 |
| (12) | EUROPEAN PATENT APPLICATION |
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| (54) | Method and apparatus for clearing pollution |
| (57) A method of clearing pollution from water in which a recovery unit, having means
for picking-up water borne pollutant, is moved by a powered vessel, characterised
in that recovery unit and said vessel are arranged in side-by-side configuration and
a deflector shield is provided to direct water and pollutant towards the recovery
unit as the vessel moves through the water. Apparatus for carrying out the method is also described. |
[0002] Pollution of our rivers, seas and oceans is increasing at an alarming rate. Both the growing risk of a major disaster, such as the wreck of an oil tanker, that has accompanied the introduction of fleets of "supertankers" for transporting massive bulk quantities of oil, and the uncontrolled discharge and spillage of fuel oil from shipping in coastal waters and harbours, are the major source of concern. Added to this, the discharge of factory waste, e.g. chemicals, and of untreated effluent directly into seas and rivers is continuing unabated in spite of the demands for action for ecological, environmental and tourist lobbies.
[0003] Existing specialist water control vessels are both very expensive and are usually designed for specific applications. For example, sea going vessels have been developed for the containment and clearing of major oil spills. However, these vessels are usually, of necessity, large and expensive and can be deployed to the scene of a "disaster" only slowly. These vessels are often only used for short periods and thus, for much of the year are idle. Thus, small harbour and coastal authorities are reluctant to incur the expense of purchasing and maintaining such vessels.
[0004] The aim of the present invention is to provide a method of, and apparatus for, controlling oil pollution that is both simple and economic, and which at least mitigates the problems of the prior art.
[0005] In one aspect, the invention provides a method of clearing pollution from water in which a recovery unit, having means for picking-up water borne pollutant, is moved by a powered vessel, wherein said recovery unit and vessel are arranged in side-by-side configuration and a deflector shield is provided to direct water and pollutant towards the recovery unit as the towing vessel moves through the water. Suitably the deflector shield is carried by the vessel.
[0006] Preferably at least two recovery units are provided, one on either side of the vessel, and the shield is arranged to deflect water towards both recovery units. The recovery units are such as to be operable in both a forward and reverse direction.
[0007] To facilitate efficient operation of the method, a deflector shield may be provided at each end of the vessel, as this means that the vessel does not need to turn around at the end of a sweep. Preferably, the or each deflector shield is generally V-shaped.
[0008] The pollutant picked-up is passed to tanks for treatment and or storage. These tanks may be provided on the recovery unit, on the vessel and/or on a separate recovery vessel.
[0009] Preferably the means for picking-up pollutant are powered by diesel engines having suitable heat recovery units to improve the operating efficiency of the engines. The heat recovered from the engines is used to heat the pollutant to aid recovery.
[0010] In order that the invention may be more readily understood, and so that further features thereof may be appreciated, embodiments of the invention will now be described by way of example and with reference to the accompanying drawings, in which:
FIGURE I shows one embodiment of an apparatus in accordance with the invention;
FIGURE 2 is a schematic plan view of one recovery unit of the apparatus shown in Figure I;
FIGURE 3 is a side elevation of one recovery unit of the apparatus shown in Figure I;
FIGURE 4 is a plan view of the recovery unit of Figure 3;
FIGURE 5 is an end elevation of the recovery unit of Figure 3;
FIGURE 6 illustrates schematically a modified roller arrangement suitable for use with the recovery units illustrated in Figures I to 4;
FIGURE 7 illustrates another modified roller arrangement suitable for use with the recovery units of Figures I to 4;
FIGURE 8 illustrates an alternative configuration of a recovery unit; and
FIGURE 9 is a plan view of an alternative form of a recovery unit.
[0011] As shown in Figure I, in a preferred embodiment, apparatus for performing the invention comprises a pair of floatable recovery units I each adapted to be resiliently attached to a towing vessel 2 by means of suitable mounting means 3. A deflector shield 4 is provided at one (or both) ends of the towing vessel. The deflector shield 4 is preferably V-shaped, having its apex aligned with the centre line of the towing vessel, and is of a size to extend downwardly into the water so as to deflect water towards each of the recovery units I as it is moved through the water. For instance a "stern trawler" could be used as the towing vessel, such trawlers being equipped with equipment suitable to mount a deflector shield. As is illustrated in Figure I movement of the towing vessel in an astern direction, as is indicated by the arrow 5, causes a deflection of surface water towards the recovery units 1, as is illustrated in Figure I by the arrows 6.
[0012] In this embodiment both recovery units are identical and so, for the sake of clarity, only one will be described in detail. As is best seen in Figures 2 to 5 each recovery unit I comprises a catamaran-type vessel having connected twin hulls 7 and 8.
[0013] When viewed from above, each of the hulls, 7, 8 has a trapezoidal profile. As shown in Figure I, when the recovery unit is assembled for operation, the hulls 7, 8 are so arranged that the shorter of the parallel sides of each hull face each other and a mouth 16 is formed. However, in some circumstances, such as for transportion, it may be desirable to reverse this arrangement.
[0014] For example, as shown in Figure 8, the longer of the parallel sides of each hull may be so positioned and locked adjacent each other that an effective "mono-hulled" vessel is formed having a more conventional "pointed" bow shape. This enables the recovery unit I to be moved more swiftly through the water and it will be appreciated that this greatly facilitates rapid deployment of the craft.
[0015] In alternative embodiments, it may be preferable for the hulls to have a more "pointed" shape, at least at one end thereof. Such alternative may be particularly useful when the unit is to be used in situations where the unit has to move through the water against a current, for example in a river or estuary. One such alternative embodiment is illustrated in Figure 9.
[0016] The hulls 7 and 8 are identical and are thus interchangeable. This provides significant advantages in the maintenance and repair of the recovery units. As is shown schematically in Figure 5, the hulls 7, 8 are internally divided to provide storage tanks 12 for oil/water and buoyancy tanks 13. Suitable pumps are provided to facilitate the filling and emptying of these tanks.
[0017] Referring again to Figures 2 to 5, two rotatable drums 9, 10 are mounted laterally between the twin hulls 7, 8, their axes of rotation being substantially perpendicular to the longitudinal axes of the units. Motors (not shown) are provided to rotate the drums, the pair of drums being adapted for both contra-rotation and pro-rotation. The speed and direction of rotation of each drum can be varied independently. At least a portion of each drum lies on, or just beneath, the surface of the water and the axes of rotation of the drums are so spaced apart that rotation of the drums causes the surface layer lying between the drums to be lifted between the adjacent surfaces of the drums from where it is passed into a storage tank or tanks 12, provided in the hull or hulls of the recovery unit. It will be appreciated that by appropriate filling/emptying of the buoyancy tanks the position of the drums 9, 10 with respect to the surface of the water can be controlled.
[0018] As illustrated schematically, and in broken lines, in Figure 8, when in the "mono-hull" configuration the drums 9, 10 may be removed and supported in suitable cradles carried on the connected hulls. Alternatively, the drums may be transported separately, for example, by the towing vessel.
[0019] The surface of each drum 9, 10 is preferably lightly rusted to facilitate the lifting of the surface water and oil. Alternatively, sleeves of absorbent, or matter attracting material could be fitted over one or both of the drums 9, 10. The provision of such sleeves is of particular benefit, as it allows the recovery unit to be easily adapted to cope with a wide variety of pollutants. For example different sleeves may be used when clearing oils fo different viscosities.
[0020] A scraper 14 is associated with each of the drums 9, 10. The scrapers 14 are attached between the twin hulls 7, 8 and are positioned so that a leading edge 15 of the scraper lies closely adjacent the outer surface of its respective drum. Preferably, the scrapers 14 are resiliently mounted so that the leading edge 15 remains closely adjacent the drum irrespective of distortions in the outer surface of the drum. Where metal drums are used, the scrapers 14 should be of an alloy to reduce the possibility of sparks.
[0021] Where an absorbent sleeve is fitted to the drum, a secondary roller (not shown) may be associated with the scraper to squeeze absorbed matter from the sleeve.
[0022] It will be appreciated that the surface of each of these drums could be the same or different, and that the surfaces may be coated with any material suitable for picking up a desired pollutant. Suitable channels are provided to direct the removed matter to the storage tanks 12.
[0023] Whilst any form of motor may be used to drive the drums, desirably diesel engines, having heat recovery units in order to increase their efficiency, are provided. Suitable heat recovery units are described in U.K. Patent Specification No. 1,191,473. It is envisaged that at least some of the heat recovered from the motor drives will be used to heat the pollutant being collected, either directly or indirectly by heating the rotating drums. This feature will be particularly advantageous where the recovery units are being employed for collecting oil products in cold environments, for example, in the sea passages around the North of Canada and Scandinavia. Each engine controls the operation of hydraulic pumps, and cargo and ballast pumps.
[0024] The pollutant, e.g, oil/water mixture, that is scraped from the surface of the drums 9, 10, is passed directly to the storage tanks 12 located within the twin hulls 7 and 8. The oil/water mixture may then be separated within the storage tanks, and the separated "free-water" discharged from the tanks and returned to the sea. In order to enable the recovery unit to cope with any mixture/oil in a water emulsion auxiliary recovery devices (not shown) are supplied to enable separation of the emulsions. For example, air-mats may be fitted to the bottoms of the tanks 12 so that air can be used to effervesce matter to the surface. This has been found to be particularly effective in the separation of mercaptans. Heat recovered from the motor and cargo pumps may also be channelled to the tanks 12 to facilitate separation of the pollutant/water mix and pumping of the separated pollutant.
[0025] The distance between adjacent faces of the drums 9 and 10 can be varied to prevent jamming of the drums by large pieces of flotsam. For example, Figure 3 illustrates two possible positions for each of the drums 9, 10. Either or both of the rotating drums 9, 10 may be adjustable to vary the distance between the drums. Preferably a hydraulic jacking means (not shown) is provided to shift the position of the or each drum as required. Using a suitable sensing device such a hydraulic jacking means may actuate automatically to move the drums apart and thus prevent damage to the surface of the drums should a potentially damaging piece of flotsam be taken up during operation.
[0026] The drums may also be resiliently mounted, so that the drums yield when pieces of flotsam are picked up and serious damage of the drums and mounting equipment is avoided.
[0027] A grill (not shown) may also be provided beneath the water surface to filter flotsam from the water between the twin hulls 7, 8 so that potentially damaging flotsam is not taken up by the rotating drums. As will be described further hereinbelow the outer surfaces of the drums may be modified so that the recovery unit can be used for the recovery of solid wastes such as plastics and/or wood.
[0028] In a particularly preferred form of this invention the recovery unit I is of a size and shape suitable for loading into a standard shipping container to facilitate rapid loading and transport of the unit or units to the scene of a disaster. Such rapid deployment capability means that recovery units may be stored at any suitable location and can be distributed as desired. For instance a centralised store could be established by a National Organisation, units being provided for local authorities on request or en masse in disaster situations.
[0029] It may also be convenient for the hull to be formed in suitably sized engageable sections that can readily be assembled for use but may be stored in either assembled or disassembled form. Such arrangement provides an additional advantage in that repair or replacement of damaged parts of the hulls may be effected by replacement/repair of discrete sections.
[0030] In operation of the arrangement shown in Figure I the two recovery units I are secured either side of the towing vessel 2, the deflector shield 4 being positioned to deflect water towards mouths 16 formed between the twin hulls of the recovery units I. Using the propulsion units of the towing vessel the recovery units can be manoeuvred through an oil slick or other area of pollution. For example if a stern trawler is used as the towing vessel the trawlers standard propulsion and control units will provide the required manoeuvrability.
[0031] Using a suitable network of sensors the safe operation of the individual recovery units can be monitored and controlled from the bridge of the towing vessel. Sensors in the storage and buoyancy tanks can provide a continuous monitor of the levels in respective tanks. This information can be used to control the pumping of ballast into and/or out of the buoyancy tanks as the storage tanks are loaded with recovered pollutant/water mix, so that the unit maintains a substantially constant draught throughout the clearing operation.
[0032] It will be appreciated that whilst the above described embodiment uses two recovery units 1, one on either side of the towing vessel 2, more than one recovery unit could be used on either side of the vessel to extend the area covered by a single sweep through an oil slick. The number of recovery units used will obviously depend upon the power of the towing vessel. However, the simple design of the recovery units I means that a chain of recovery units could be arranged attached to each other in a side-by-side manner with more than one towing vessel interspaced in this chain to provide the propulsive and manoeuvring ability required. Using such an arrangement a very wide area of sea could be swept in a single movement and rapid containment and clearing of an oil spill could be effected.
[0033] It may also be desirable, in some applications, to use only a single recovery unit, for example, when operating in confined waters, as in a harbour. It is also desirable that the two hulls are so connected that the spacing between them can be varied, for example so that the unit can enter confined spaces.
[0034] When the storage tanks are full these can be pumped out either to storage tanks on the towing vessel, or to a standard recovery tanker. Using established transfer techniques a recovery tanker could be arranged to be permanently connected, by suitable pumping connections, to the storage tanks of one or more of the recovery units. This arrangement greatly extends the operating time of the pollution recovery unit as it avoids "down time" for off-loading of the recovered pollutant.
[0035] Referring now to Figures 6 and 7 modifications to the. rotating drums 9 and 10 are illustrated. As shown in Figure 6 a number of tines or hooks 17 can be provided around the cylindrical surface of the drums, the tines 17 being so positioned that the tines of adjacent drums 9 and 10 pass between each other without contact. This embodiment is particularly suitable for use in harbours and river estuaries where a high level of solid pollutants is present in the water as well as oil and chemical waste.
[0036] Figure 7 shows a further modification of the drums 9 and 10 that is particularly suitable for clearing heavy debris such as baulks of timber, such as are typically found floating in tidal rivers (e.g. the river Thames). In this case the drums 9 and 10 are rotated in the same direction, timber being picked up and passed over both drums to be conveyed to storage barges 18 towed aft of the direction of movement of the unit I. In this case the drums may be provided with resilient tines 19 to avoid damage by the heavy timber.
[0037] Where the recovery units are being used primarily to clear solid pollutants, an optional conveyor belt (not shown) is provided on each of the hulls. The conveyor belts are powered by the same motor that operates the rotating drums. The two belts may be arranged to convey recovered material either in the same direction, to a single storage vessel, or in opposite directions, to a pair of storage vessels. It will be appreciated that the direction of movement of each conveyor may be matched to the direction of rotation of one or both of the drums. This is particularly useful when the drums are spaced apart to act individually.
[0038] Each recovery unit may be provided with self-propulsion units, such as outboard motors for use when clearing pollution in confined areas such as harbours where there is inadequate space for a towing vessel to easily manoeuvre the recovery units.
[0039] Referring now to Figure 9, an alternative form of a recovery unit 100 comprises a pair of spaced apart, connected hulls 107 and 108. As distinct from the hulls 7 and 8 described above, each of the hulls 107, 108 is formed to define an apex portion 107a, 107b and 108a and 108b, respectively, at each end thereof. When arranged as shown in Figure 9, a side of the apex portion of each of the hulls 107, 108 act to define an entry or mouth 116 at each end of the unit for directing water and pollutant to rotatable drums 109, 110. The recovery units 100 are similar in other detail to the recovery units I described above and thus further detailed description will not be given here.
[0040] It will be appreciated that the recovery units 100 may be used in operation in a manner similar to that described above. The more pointed shape of the hull units of this embodiment allow the recovery units to move through the water at a faster speed, although in some circumstances it may be desirable to use additional boom elements (not shown) to control directing of the water and pollutants.
[0041] Preferred forms of recovery units of the invention provide significant advantages in that they may conveniently be used for other purposes when not required for pollution clearing operations. This facility means that the expense of purchase and storage of specialised pollution clearing equipment may be offset by making use of the equipment during periods when conventional equipment is routinely stored.
[0042] Thus, the pumping capacity, winches and power drives may be employed in a variety of operations in harbours and docks. One convenient use of the unit is a mobile "dry dock". In such use unnecessary drums and other peripheral equipment may be removed from the unit. A boat, for example, a yacht, could then be secured between the hulls, with the hulls positioned low in the water, by suitably adjusting the buoyancy of the hulls as described above. By increasing the buoyancy of hulls, i.e. pumping water out of the tanks in the hulls, the hulls can be caused to rise, lifting the yacht from the water to enable inspection and maintenance of the hull of the yacht.
I. A method of clearing pollution from water in which a recovery unit, having means
for picking-up water borne pollutant, is moved by a powered vessel, characterised
in that recovery unit and said vessel are arranged in side-by-side configuration and
a deflector shield is provided to direct water and pollutant towards the recovery
unit as the vessel moves through the water.
2. A method according to claim I, characterised in that at least two recovery units
are provided.
3. A method according to claim I or claim 2, characterised in that at least two recovery
units are provided, at least one on either side of the vessel, and a shield is arranged
to direct water towards each recovery unit.
4. A method according to any one of claims I, 2 or 3, characterised in that the deflector
shield is carried by said vessel.
5. A method according to any one of claims I to 4, characterised in that the recovery
units are operable in both a forward and reverse direction.
6. A method according to claim 5, characterised in that a deflector shield is provided
at each end of the vessel.
7. A method according to any one of claims to 6, characterised in that said deflector
shield is generally V-shaped.
8. A method according to any one of claims I to 8, characterised in that the deflector
shield is pivotally attached to the vessel.
9. A method according to any one of claims I to 8, characterised in that the recovery
units are adapted to pick up pollutant from on and/or near the surface of the water.
10. A method according to any one of claims to 9, characterised in that the pollutant
recovered is passed to tanks for treatment and/or storage.
II. A method according to claim 10, characterised in that the recovery unit is a catamaran
type vessel and the storage tanks are provided in each of twin hulls.
12. A method according to any one of claims I to 11, characterised in that the means
for picking-up pollutant comprises a pair of rotating drums.
13. A method according to claim 12, characterised in that said pair of drums are adapted
for contra-rotation.
14. A method according to any one of claims I to 12, characterised in that the means
for picking-up pollutant are powered by a diesel engine having suitable heat recovery
units to improve the operating efficiency of the engines.
15. A method according to claim 14, characterised in that said engines are arranged
to power pumping units .
16. A method according to claim 14 or claim !5, characterised in that the heat recovered
from the engines is used to heat the pollutant or at least some of the pollutant engaging
components of the recovery unit or units to aid recovery.
17. A method according to any one of the preceding claims, characterised in that a
plurality of recovery units are arranged in side by side relationship to form a chain
of recovery units, the chain of units being interspersed with as many towing vessels
as required for efficient manoeuvering of the units, and deflector shields being positioned
as required to deflect water and pollutant towards the recovery units.
18. Pollution clearing apparatus for carrying out the method of any one of claims
I to 18.
19. Pollution clearing apparatus according to claim 19, characterised in that the
or each recovery unit is switchable between a "twin-hull" configuration and an effective
"mono-hull" configuration.