GB2025247A - Removal of oil from the surface of a body of water - Google Patents

Abstract

Oil is removed from the surface of a body of water by directing a fluid downwardly on to the surface to force oil to a position below the surface where it is entrained by current flow into a duct. A device for effecting the removal of oil from the surface of water includes a water-powered eductor whose inlet is suspended below the surface of the water from a floating frame; an annular array of nozzles directing water jets downwards to force floating oil towards the inlet; and a conduit whereby an oil-water mixture is conveyed from the outlet side of the eductor. The conduit may carry the oil-water mixture to a gravity separator tank which may be on shore or in a conventional oil tanker floating on the body of the water or to a discharge line which can deliver the oil to a substantial depth below the surface or to a preselected tidal stream. An oil dispersant material may be mixed with the water supplied to the eductor and jets in cases where the oil is to be dispersed in the body of water either at depth or in a tidal stream. The water supplied to the eductor and jets may be recycled from the separator tank and may be heated. <IMAGE>

Description

SPECIFICATION Improvements relating to the removal of oil from the surface of a body of water This invention relates to a method of, and devices and systems for, removing oil from the surface of a body of water, either to recover it in a form suitable for further processing orto return ittothe body of water in a dispersed form. Devices in accordance with the invention described below are suitable for removing oil split upon the surface of bodies of 'water such as docks, rivers and the open sea, orto augment the use of chemicals in the dispersal of oil in the open sea or inshore waters.

According to one broad aspect my invention pro vides a method for removing oil from the surface of a body of water which comprises impacting a fluid downwardly on the surface of a body of water to force oil to a position below the surface and causing it to be entrained by current flow into an inlet to a duct, and pumping the resulting oil/water mixture to a desired location.

Another broad aspect provides a device for remov ing oil from the surface of a body of water compris ing: a) a fluid transfer line with (i) an inlet for position ing below the surface of the body of water; (ii) an outlet for discharging fluid at a desired location; and (iii) pump means for indrawing water from the vicin ity of the inlet and transmitting it to the delivery end; and b) a fluid delivery circuit for directing fluid at the oil bearing surface from above and in a direction towards the said inlet with sufficient force such that, in use, floating oil will be driven below the surface of the water into the vicinity of the inlet and a resulting mixture of said driven oil and water will be indrawn into the fluid transfer line.

In the recovery mode my device is not intended as an oil/water separator and depends upon a simple gravity separation system to separate the oil from the water with which it is entrained during the recovery process.

My device differs from conventional recovery "Skimmers" in that instead of attempting to skim the oil from the surface of the water it utilizes e.g. a jet of water to force the oil into contact with the inrush of water to a suction duct positioned below the oil/water interface. Water is thereby used as the veh icletotransportthe oil to the separatortanks or other discharge location.

In one dispersal form my device differs from con ventional means of applying chemical dispersants in that instead of spraying the chemical over the sea and oil surface in general and thereafter creating an emulsion by means of "breaker boards" towed at speed through the oil slick, the oil and sea water are first emulsified by the Device as in the Recovery Mode and only during or after this initial emulsifica tion is effected is the chemical introduced.

Preferred embodiments of my invention will now be described by way of example only, with reference to the accompanying drawings, in which: Fig. 1, is a front elevation of an oil recovery device; Fig. 2 is a plan view of the device shown in Fig. 1; Fig. 2A is a side view of a conventional eductor; Figs.3 to 9, illustrate howthe device of Figs. land 2 may be used in oil recovery operations; Fig. 10 illustrates a simple form of my device in combination with a collecting tank; Fig. 11, is a front elevation of another embodiment in accordance with my invention adapted to be suspended in the body of water under treatment; Fig. 12, is a front elevation of an embodiment similar to that of Fig. 11 but adapted for floatation in the body of waterto be treated; Figs.13 and 13A are front elevations of two more embodiments in accordance with the invention; Fig. 14, illustrates yet another oil recovery device in accordance with the invention; Fig. 15, illustrates an eductor inlet equipped with a steam ring; Fig. 16, illustrates a "pig" for use in heating a cold water stream with steam; Fig. 17A, illustrates a continuous process for separating oil from an oil/water mixture; Fig. 17B, illustrates a batch process for separating oil from an oil/water mixture; Figs. 18A and 18B illustrate a system comprising a single device, suitable for use in recovering oil spilt e.g. in the vicinity of an oil terminal;; Fig. 19 and 20, illustrate oil recovery systems comprising a plurality of devices in accordance with the invention and an oil tanker; Figs. 21 and 22, illustrate the use of devices in accordance with the invention for dispersing oil respectively offshore and inshore; Figs. 23 to 25, illustrate booms and hoses suitable for use in the practice of embodiments in accordance with the invention; Figs. and B, illustrate hoses suitable for discharge of a body of water; Figs. 27A and B, illustrate respectively a longitudinal and transverse section of a disposable separation tank; and Fig. 28 illustrates a floating disposable separator for use particularly offshore; Fig. 29A is a plan view of a pilot plant apparatus for removing oil from the surface of water; Fig. 29B is a side view of the apparatus shown in Fig. 29B; Fig. 29C is a view from above of the apparatus of Figs. 29A and B in a test tank; Fig. 29D is a part sectional side view of the arrangement shown in Fig. 29C.

Referring to Figs. 1,2 and 3 an eductor 1 is mounted in a framework of conduit which serves the dual purpose of supporting the eductor and ancilliary components and as a means of conveying the driving fluid to the eductor and the co-mingled oil and water discharges away from the eductor.

The four legs of the framework are connected top and bottom to header boxes 2 and 3. The discharge hose 2 is connected to the top header 2 whilst the eductor discharge flange is bolted to the bottom header 3. Three legs of the framework 4 are open to the headers whilst the fourth leg 5 is blanked from the headers (see Fig. 2).

Leg 5 is provided with a flanged stub piece 5' at the top to which the drive fluid hose is connected and a flanged stub piece 6' at the bottom to which the eductor drive connection 6 is bolted. Supported from the superstructure of the frame by means of jacks 7 is a dish shaped tray 8 at the center of which is a ball jointed stub piece 8' which slides into an extension of the eductor suction.

The purpose of the ball jointed stub piece is to direct the oil and water from the tray 8 into the eductor suction whilst allowing verticle and horizontal adjustment of the tray relative to the surface of the water. One side of the device is provided with a fender 9 which is connected to two of the vertical legs of the frame.

The face of the fender is lined with shock absorbent material and a lightweight vertical extension 10 is bolted to the rear of the fender to serve as an oil retaining boom.

The whole device is supported in the water by means of four cylindrical floats 11 which are mounted coaxially with the four legs of the frame.

Supported from the superstructure of the frame and concentric with the collecting tray is a smaller bore conduit 12 which is equipped at intervals with nozzles 13. This Spray ring is connected via a valved connection 14 to the drive fluid stub piece.

In the case of heavy viscous oils such as heavy fuel oil, weathered crude oil etc., which present a high resistance to flow through a hose or pipeline, the resistance is lowered by co-mingling them with copious quantities of water. This co-mingling is effected in two stages. In the first stage jets of water from the nozzles are directed upon the surface of the oil. The oil is thus broken up into smaller pieces which are carried by the force of the jets below the surface of the water where they come under the influence of the inflow of water 15 to the eductor.

They are thus carried into the eductor.

In the eductorthey are co-mingled with the driving fluid 16 which provides the second stage of comingling and are then forced by the energy of the driving fluid along the hose to the storage vessel.

The nozzles 13 which supply the jets of water can be permanently mounted on a supply pipeline of circular form which is secured to the superstructure of the recovery device or preferentially upon radial spokes enamating from the centre of the superstructure, in which position they can be adjusted for position or angle.

Fig. 3A shows an arrangement which may be adapted when a large tanker 17 is used for storage/separation on the open seas. The oil water mixture is directed first into the top of the compartment 18 of the storage vessel; which compartment has previously been filled to capacity with clean water.

The bottom of this compartment is connected by a pipeline 19 to the top of a second compartment 20 which likewise has been filled nearly to capacity with clean water. The bottom of the second compartment 20 is connected by pipeline 21, to a pump 22, the discharge side of which is connected via a hose 23 to the drive side of the eductor 1.

In the first compartment 18, owing to the differ ence in the density of oil and water, the oil compo nent of the effluenttends to rise to the surface whilst the water component tends to sink and displace the relatively clean water from the lower part of the tank.

The displaced water flows via the interconnecting pipeline 19 into the top of the second tank 20. In the second tank 20 any droplets of oil carried over the first tank float to the surface whilst the water component displaces clean water from the bottom of the second tank 20 to the suction of the pumps 22 and thence to the eductor drive connection. Excess water is routed by the vessel's suction system to another, empty compartment, or overside. Should the friction head of the transfer pipeline be in excess of the pressure rating of the vessel's tanks the transfer from compartment 18 to compartment 20 can be effected by means of one of the vessel's pumps.

If so desired, (and as illustrated below) steam can be injected to the drive fluid in order to heat the effluent and reduce the viscosity of the oil component. Likewise, chemical emulsion breakers can be injected into the drive fluid in order to accelerate the separation of oil and water from semi-permanent emulsions that tend to form when water and some crude oils are mechanically co-mingled. Permanent heating coils in the vessel's tanks can also be utilized to heat the effluent.

Suitable storage/separation vessels are: (a) Tankers, either moored alongside jetties or floating freely at sea.

(b) Terminal effluent systems which normally incorporate a large holding tank or tanks.

(c) Multi-compartment road tanker vehicles.

Suitable driving mediums are water as mentioned above which can be water recirculated from the separation process or water from the Vessels or Terminals' utility facilities. Other suitable mediums are steam or air, again supplied from the Vessels or Terminal Utility Facilities.

In the case of recovery of oil remote from Terminals and Ships (Inland spillages) a portable pump drawing water from the separation process can be used or portable air compressors can be used.

Fig. 3B shows an arrangement similar to Fig. 3A when a large tanker 17 is used for storage/separation alongside a Terminal.

Fig. 3C shows the arrangement when the recovery device 29 is connected to the shore effluent system 24 and driving fluid is obtained from the Terminal utility facilities 25.

Fig. 4 shows the arrangement when a large tanker 17 moored in midstream is used for storage and separation and floating booms 26 are used to direct the oil to the recovery device 29.

Fig. 5 shows the arrangement when a large tanker 17 moored alongside a wharf 27 is used for storage/separation and booms 26 laid across the Harbour entrance 28 direct oil entering the harbour two the recovery device 29.

Fig. 6 shows a similar arrangement to Fig. 5 but, in this case, the tanker 17 is moored across the harbour entrance 25 and a boom 26 between the Ship 17 and the piers 30 directs oil to the recovery device 29.

Fig. 7 shows the arrangement when oil is recovered from the open sea under still air conditions.

Two small Motor Fishing Vessels, or similar 31, draw the Vessel 17 slowly broadside through the oil slick whilst booms attached between the recovery device 29 and the sterns of the towing vessels 31 direct the oil to the recovery device 29.

Fig. 8 shows the arrangement when oil is recovered from the open sea and there is some wind. In this case the wind effect on the ship 17 causes it to drift faster than the oil and oil, in consequence, piles up on the lee side 32 of the vessel 17 where the recovery device 29 is positioned. Floating adjustable, Booms 33, positioned at the fore and aft extremities of the vessel prevent the oil escaping around the ends of the vessel.

A large drogue 34 deployed on the windward side of the vessel provides the means whereby the vessel can be maintained broadside to the wind.

Slacking on the forward hawser 35 will cause the Vessel's head to pay off whilst slacking of the after hawser 36 will cause the stern to payoff.

Fig. 9 shows the arrangement when oil is recovered from an inland lake or waterway 37. The storage vessel, in this case, is a large multi-compartment road tank vehicle 38, which is filled initially with clean water. The energy to power the eductor is derived from a portable, dieseldriven pump 39, whilst a floating boom 26 is used to draw the oil to the vicinity of the recovery device 29.

Referring to Fig. 10 it will be seen that a suction duct, or ducts, (40) is positioned slightly below the oil/water interface with its axis perpendicular to the interface. A nozzel (41) (or nozzles) is positioned above the oil/water interface and the jet of fluid issuing from the nozzle 41 is aimed axially of the suction duct 40. The suction duct(s) is connected to a storage/separation facility (42) via flexible hose (43) and pipeline (44) and at some point within this run of hose/pipeline a pump or eductor (45) is installed.

Three alternative positions are shown.

The nozzle is supplied with fluid under pressure via flexible hose (46) and pipeline (47). The fluid can be supplied ex Terminal or Ship Utility Facilities or it can be water bled from the separation process; in which case it will be slightly contaminated with oil.

The whole is mounted in a frame (48) which, in this case, is supported by a sling from a derrick or crane.

Figs. 11 to 13 show various arrangements of nozzle/section duct which are all based upon a power unit (pump or eductor) installed at the upstream end of the system. However, as pointed out previously, the actual power unit can, within reason, be positioned anywhere in the transfer line.

Fig. 11 shows an eductor (1) and nozzle (50) installed in a framework of conduit, one leg (51) of which serves to convey the discharge from the eductor to the interconnecting hose and thence to the storage/separation facility. The other leg (52) serves to connect the drive connection of the eductor to a flexible hose and thence to a source of high pressure fluid. The drive fluid can be supplied from Ship or Terminal utility facilities or from the separation process. It can be supplied also by portable pump taking suction from the sea, dock or separation process.

A branch connection (53) from the eductor drive line supports the nozzle and serves also to direct high pressure fluid to the nozzle. A control cock (54) provides the means for adjusting the strength of the jets.

The eductor can be driven by any fluid under pressure such as compressed air, steam etc., although in certain circumstances when using any medium other than a liquid a separate liquid supply to the nozzle will be required.

The inlet to the eductor is provided with a sleeve (55) within which suction branch (56) slides. The mouth of the branch is suitably radiased in order to reduce entry losses. In preferred forms it is capable also of limited adjustment to suit varying sea conditions.

In smooth water conditions the device can be slung by lifting eyes (57) from the dockside crane or Ship's derrick and lowered to the appropriate position relative to the oil/water interface (Fig. 12A) In otherthan smooth water conditions the Device must be supported by floats (11) as shown in Fig. 1 2A. The trunnions (58) allow the device to maintain a generally vertical attitude independent of the lateral movement of the floats, whilst the vertical bights in the connecting hoses to allow the unit freedom to rise and fall on the swell.

Fig. 13 depicts a Recovery Device in which the energy is provided by a Deepwell Pump. Extensions top and bottom of the pump (59) support the suction duct (56) and nozzle (50). The mouth of the suction duct is radiased to minimize entry losses and the duct itself is a sliding fit into the suction extension piece (55) thereby allowing a limited amount of vertical adjustment to suit varying conditions of sea and swell.

The pump can be driven by any rotative form of power unit; suitable units being Diesel Motor, Electric Motor, Pneumatic Motor or Hydraulic Motor. The first two, however, introduce a potential hazard when recovering inflammable products.

The power unit (60) is close coupled to the pump 59 in the conventional manner; the drive shaft passing through the axis of the discharge casing. The nozzle receives a supply of high pressure liquid via connection (61) and flexible hose (62) whilst the pump discharge is connected to the storage/separation facilities via flexible hose (63).

A lifting eye (59) mounted on a cantilever bracket (64) in conjunction with lifting eye (57) mounted on the discharge extension piece (65) provide the means whereby in still water conditions the device can be slung from a dockside crane or Ship's derrick and lowered to the appropriate level with reference to the oil/water interface.

As shown in Fig. 13A in other than still water conditions the cantilever bracket can be replaced by a stub piece 66 and the unit supported in trunnions 58 on floats (11).

Fig. 14 shows a device powered by an eductor 1 in which the drive water and the nozzle supply water are heated in order to increase the temperature and thereby reduce the vicosity of entrained Heavy Fuel Oil. The heating can be effected by means of the vessel's "Butterworth" heater 61 as shown or, if the Vessel is not equipped with a heater, by means of a portable "inline" heater installed between the pump discharge manifold and the connecting hose. Alter natively, a "Pig", as shown in Fig. 16 can be used to heat the drive water.In extreme ambient conditions the hot water can be augmented by means of direct injection of steam into the suction branch as shown in Fig. 15 in which a steam ring 67' is located around the radiased opening 68 of eductor 1, steam being supplied via hose 69, and steam jets 70 being directed radially inwardly of the ring and into the mouth of the eductor opening.

The gravity separation of an oil in water emulsion on which the effectiveness of the recovery mode device depends is a well known technique on Tankers. It has been used in various forms for many years and is an essential feature of the "Load on Top" technique The optimum positioning of the discharge hose in a Vessel's tanks will vary from Vessel to Vessel but experiments with the "mock-up" depicted in Fig. 30 indicate that the outlet of the hose should be positioned near to the bottom of the tank and as far as possible from the tank suction bellmouth. In the trial illustrated in Fig. 30 an oil/ water emulsion or mixture was generated by vigourous stirring in vessel 100 using a conventional electric drill 107 with the stirrer attachment. Vessel 102 was initially filled with clean water and connected by a syphonic arrangement 103 to collecting vessels 104/105.After the emulsion had formed vessel 100 was connected to vessel 102, as shown, in the oil/water mixture allowed to flow. As illustrated oil settled out, drifting upwardly and across vessel 102, whilst relatively uncontaminated water passed through syphon arrangement 103. However, in the matter of gravity separation conventional tankers lend themselves to the technique and few experienced Tankermen will experience difficulty in deciding upon the optimum position for the hose. Conventional Tankers also have other advantages in connection with the recovery of offshore pollution viz: (1) The segregation of the cargo section into several individual tanks coupled to the comprehensive pipeline system enable recovery, separation and storage to take place concurrently.

(2) The cargo pumps and Utility Pumps (Fire, "Butterworth" etc.) can be used to power the device and later to discharge the recovered oil to a Shore Installation.

(3) Steam from the Vessel's steam plant can be used to heat the drive water or provide direct steam injection to the suction branch thereby increasing the temperature and reducing the viscosity of Heavy Fuel Oil to emulsification level. Thereafter the tank heating coils can be used to maintain the recovered oil at pumpable temperature or assist in the break down of oil in water emulsions resulting from the recovery process.

(4) The bulk of a handy sized vessel acts as a very effective Boom (upwards of 550 feet in length in the case of a handy sized 18,000 DWT. Vessel) forthe purpose of building up a continuous oil layer in the vicinity of the device. In suitable weather conditions a bight of flexible boom deployed between the sterns of two small tugs or MFVs attached to the bow and stern of the Tanker can be used to augmentthe boom effect of the Tanker itself.

I describe belowtwo basic techniques for utilizing a Tanker's cargo tanks for the gravity separation of oil from an oil in water emulsion viz: (a) A continuous process in which the discharge from the device is routed to the bottom of one tank, which serves to retain the separated oil, whilst the water component is displaced by the incoming liquid and routed via the Vessel's pipeline system and anothertank in series, to a pump and thence used to power the device or is discharged overboard.

(b) A batch separation system in which two tanks are used alternatively to receive and separate the oil from the emulsion discharged by the device.

Fig. 17A illustrates the continuous separation process and it will be seen that the discharge from the Recovery Device is led via hose (71) to the bottom of a cargo tank, (8) which has previously been filled with clean water. In this tank the oil component separates out and floats to the top of the tank whilst the water component is displaced by the discharge from the device along suction line (19) discharge line (19') and flexible hose (19") into the top of a second tank (20) which has previously been partly filled with clean water.

In this second tank any particle of oil carried over from the first tank gravitates to the surface whilst the water component is withdrawn via suction line (21) and pump (22) and routed to the device via discharge line (23) and flexible hose (23') or is discharged overboard via bleed-off hose (23"). When the oil/water interface in the first tank approaches the bottom of that tank, which will be indicated by a significant increase in the amount of oil carried over to the second tank, the discharge hose from me device is moved to another tank and the foregoing procedure is repeated.

Fig. 17B depicts one preferred batch separation technique and shows how this can be effected with a typical direct line system with the minimum of valve manipulation. Initially the centre pump (72) taking suction from the sea supplies water under pressure via the centre discharge manifold (73) and flexible hose (74) to the device (75). The discharge from the device, which consists of an oil in water emulsion is routed via flexible hose (76); starboard pump discharge manifold (77); loading drop (78) and star board suction line (79) to No. 3 tank.

When No.3 tank has been filled to capacity the bridging hose (80) interconnecting the port and star board discharge manifolds is opened and loading drop (70) is closed. The discharge from the device is then routed via loading drop (81) and Port suction line (82) to No.7 tank. After a short interval (15 minutes or so) to allow the oil to separate from the water in No.3 tank loading drop (70) is partly opened and loading drop (81) is partly closed in order to route part of the discharge from the Recovery Device to the bottom of No.3 tank and thereby displace the separated oil via small bore hose (83) (a "Butter worth" hose will suffice for this purpose) into No.2 tank.

Thereafter loading drop (78) is closed; Loading drop (81) is fully opened and the pump is lined up to take suction from No. 3 tank thereby utilizing water from thattankto power the device.

When No. 7 tank is full to capacity the foregoing procedure is repeated in respect of that tank. The output from the Recovery Device is routed to No. 3 tank; the pump is lined up to take suction from the sea and No. 7 tank is closed. After settling the separated oil from No. 7 tank is displaced to No. 8 tank via small bore hose (84) in the manner described above for No. 3 tank.

The above sequence is repeated until all tanks with the exception of Nos. 3 and 7 have been filled with recovered oil or until the pollution has been dealt with.

The excess water which will gradually build up in tanks 3 and 7 due to the inbalance between the amount of water required to power the device and the amount of emulsion discharged by the device plus the water taken direct from the sea can be discharged overboard via the bleed-off hose (88) on the drive line. In the event that the output of one pump is insufficient to maintain drive line pressure when operating the bleed-off, a second pump can be operated in parallel with the first without affecting the line up procedure.

The various suction modes of the pump can be controlled via manipulation of the two bulkhead valves (85) and (86) and seavalve (87) and should present no problem to an experienced Tankerman.

The way in which the device is deployed is importantto its effectiveness.

Figs. 18a and 18b depict a suitable arrangement when a single unit is used to recover the oil spilt in the vicinity of a Terminal. In Fig. 1 6a the Vessel's own pumps and tanks are used to power the device and carry out the initial separation whilst the effluent excess is discharged to the shore effluent tank 88.

In Fig. 18b the device is powered by fluid from the Terminal utility facilities and the discharge is routed, via a booster pump 89 if necessary, to the Terminal effluent tank 88.

Fig. 19 depicts a suitable arrangement when a conventional Tanker 17 is used in conjunction with a device in accordance with the invention to recover an oil spillage offshore. In this case a number of Recovery Units 29 are deployed along the lee side 32 of the Vessel which is allowed to drift, or is towed, slowly through the oil slick. In suitable weather conditions the amount of oil directed towards the devices at each pass can be increased by means of a bight of flexible boom 26 connected between the sterns of the tugs 31 as shown.

When the number of devices in accordance with the invention are deployed concurrently, as in this case, their discharges are collected into a common hose at deck level and this in turn connects to the hose leading to the bottom of the first tank. The individual hoses conveying drive liquid to the devices are likewise supplied from a common hose at deck level.

Fig. 20 depicts a suitable system for when a Tanker 17 is used in conjunction with the device 29 in accordance with the invention to recover oil which has drifted into bays or inlets or so close inshore that the Vessel cannot be allowed to drift through the slick. In this case the Vessel is anchored and by means of a spring from the poop deck to the anchor cable is angled across the prevailing tide or wind. The tide or wind thus carries the oil to the Vessel where it is picked up by a series of devices deployed along the weather side of the Vessel.

As in the case of Fig. 19 portable booms 26 can be used in suitable weather conditions in order to channel the maximum amount of oil towards the Vessel.

In the dispersal mode the device in accordance with the invention is deployed in the same manner as in the recovery mode but the emulsion discharged by the device is returned to the sea instead of being routed to a separator tank. The need to separate and store the recovered oil is thus eliminated and the device can be actuated from any craft of a size capable of keeping the sea in the prevailing weather conditions. Alternatively, the device can be actuated by shore based portable equipment.

When used for offshore dispersal a hose 90 can be connected to the discharge of the device and allowed to hang vertically in the water. The emulsion is thus discharged at some distance below the sea surface and the buildup of chemical dispersant in the surface layer is thus inhibited. Fig. 21 depicts a suitable system from which it will be seen that the liquid dispersant 91 is introduced to the suction side of the actuating pump 92 and is, therefore, applied to the oil layer via the jet as well as to the oil/water emulsion via the eductor drive connection.

When used forthe dispersal of pollution from inshore waters the discharge is conveyed via a hose laid on the seabed to a point offshore, preferably in the main tidal stream. The device in accordance with the invention can be actuated via a pump installed in a shallow draft craft or via a portable pump located on the foreshore and taking suction from the sea 93.

Alternatively, the device can be modified and deployed from a mechanical excavator 94 as shown in Fig. 22. As in the case of offshore dispersal the dispersant chemical is introduced into the suction side of the actuating pump.

Regarding the dispersal of Heavy Fuel oil the "Drive" water can be heated via direct steam injection into the drive line from an installed or a portable boiler. Alternatively when a conventional Tanker is used as the attendent craft the tank cleaning heater can be used for the purpose of heating the "drive" liquid.

It is believed that, in addition to the impacting fluid driving oil below the water surface to cause it to mix with water flowing into a discharge duct, when the impaction occurs immediately over the opening of the discharge line the energy or head imparted to the oil/water mixture in the discharge line may assist in the pumping process. This is so in the embodiment of Fig. 29 described below. Fig. 29 illustrates apparatus used in a pilot plant study, made up of a suction U-bend 400 of 141" tubing with, at one end, a centrifugal pump 401 with a 2" four bladed impeller connected thereto by a sliding extension 402; the pump is driven by an electric motor 403 by way of a drive belt 404; the pump has a 3t' diameter discharge orifice 405 connected to discharge line 406.Conduits 407,408 are connected respectively to a domestic hot water source, and a heated hot water tank, and have outlet nozzles 407' and 408' respectively. The above described assembly is mounted on a frame 409 equipped with floats 410 so that the assembly floats on a body of water with the inlet 400' to suction bend 400 below the water surface as shown.

Nozzle 408' is located proximate inlet 400' and nozzle 407' directly above.

I have found that when pump 401 is driven, without water being delivered through nozzle 407', 408' water is drawn from below the surface, but the surface, and any oil thereon is undisturbed. When, additionally, water is delivered through nozzles 407', 408', water from nozzle 407' impacting, under pressure, on an oil contaminated surface, as shown, oil is rapidly removed, via the suction tube 1, from the entire surface of the tank 411. Discharge from the pump is passed to separator 412; oil separates out and fairly uncontaminated water passes out from the bottom.

The deployment, recovery and subsequent cleaning of sundry oil recovery equipment such as flexible hose, portable tanks etc., is a difficult and dirty job and often causes almost as much environmental damage as the primary oil spillage, especially in the immediate hinterland bordering an oil poluted foreshore.

It is envisaged that these problems, in the preferred practice of the present invention, may be alleviated by the use of tubing which is light in weight, easily welded on site by portable equipment and low enough in cost to be disposable; either by burying or burning.

Suitable tubing in gauges up to 1500 examples of which are known in the art as "layflat" tubing is produced by the extrusion/blow technique and the maximum continuous length available depends upon the width and the gauge. However the 15 feet width (i.e.

equivalent to a circumference of 30 feet) is available up to a length of 75 feet in 1500 gauge and a portable disposable tank formed from such a tube will have a capacity of seventy tons or thereabouts.

In the smaller widths considerably longer lengths are available and these can be joined to form even longer lengths.

Figs. 23 to 26b depict various ways in which tubing can be used as Booms or Hoses.

Fig. 23 shows a boom 500 which could be used to encircle an oil spillage at sea thereby preventing it from spreading or breaking up until such time as it could be dealt with either by dispersal or recovery. In this case air and water connections 502', 503' are fitted to the tube close to one end which is then closed by welding. Thereafter a continuous longitud inal weld 501 is made to divide the tube into two section. One of these sections 502 is filled with low pressure air and serves to contain the oil above sea level whilst the other section 503 is filled with water and serves to prevent the oil from under running the Boom. Two small vessels would be needed for the deployment of such a Boom.One would accomodate a low pressure compressor and a low capacity pump by which the Boom would be filled with air and water as the second vessel deployed the tubing from the drum on which it is stowed prior to use.

Fig. 24 shows a Boom similar to that of Fig. 23 but in this case one section 503 is filled with sand to act as ballast. As the sand has to be introduced as the tube is deployed the tube itself is folded back upon itself and longitudinally welded immediately after the sand is introduced from a hopper. In this case the first launch would contain the compressor for air fil- ling one section whilst the second launch would contain the sand hopper and continuous welding machine whereby the sand is introduced and the seam welded.

Fig. 25 depicts a disposable hose constructed in the manner described for the Boom in Fig. 24 above.

In this case the sand filled section is used to maintain the hose on the bed of the sea and the section which is air filled in the case of a Boom serves as a hose to convey emulsified oil out into deep water.

Such a Boom could be deployed by a single launch which would sand fill and weld the ballast section leaving the other section for use of the shore based pump.

Figs. 26a and 26b show a length of "layflat" tubing ballasted with sand at one end 504 so that it will hang vertically in the water when used to convey emulsified oil to a point far below the sea surface.

Fig. 27 illustrates a portable and disposable storage/separation tank formed from layflat tubing supported by standard smooth faced shuttering and scaffold units.

The tank comprises side walls 200 constructed of plyboard shuttering supported by scaffolding units 207. The walls are provided with an inlet duct 202 for connection to an outlet from a device in accordance with the invention; this inlet 202 is located close to the bottom of the tank, and a deflector piece 203 is located at the inner side of the duct 202. Relatively uncontaminated oil is withdrawn through channel 204 between vertical end piece 205 and a sidewall 206, by pump 207, and discharged to the body of water or a second tank through line 208 and possibly to an eductor e.g. through line 209. Separated oil is withdrawn via connection 210 over angled wier piece 211.The arrangement of inlet and outlet connectors or ducts and defiector, vertical end piece and wier piece is such as to induce a flow of oil particles generally upwardly and across the tank as shown. In the tank shown inlet and outlet 202,210 are incorporated in an end piece 212 with a lip 213 to which one end of a "layflat tubing" is attached. Similarly outlet channel 204 is provided in end piece 214 with lip 215 to which the other end of the "layflat" tubing is attached. The tubing can be laid e.g. on a sand bed or other flat surface.

Fig. 28 depicts a floating, disposable separator formed from layflattubing which could be used off shore to accomodate the recovered oil until such time as a suitable vessel is available to transport the oil to a Shore Terminal. The Separator is formed by first inserting the air connection 300 then turning the tube back upon itself and making two welds 302/3 to form the buoyancy rings 304/5 as shown. The lower end is likewise turned back upon itself, filled with sand and then welded to form a ballast ring 306 for the purpose of maintaining the separator upright in the water. Spreader Hoops 307 as shown are then lowered into the tube to prevent it collapsing.

A Separator such as this would be effective when allowed to drift with the oil slick. It would probably not be effective if held against tide or wind.

Preferred forms of my device in the recovery moje are believed to have the following advantages: (1) The suction duct need not be positioned precisely with regard to the oil/water interface and the device is, therefore, capable of operating over a wide range of sea and swell conditions.

(2) The turbulance created by the jet in combination with turbulance within the pump or eductor and the discharge hose forms an oil/water emulsion in which the oil component shows little tendency to "plate out" on the walls of the pipe. The recovered oil can, therefore, be transported via comparatively small bore lines. This tendency to form an oil/water emulsion is common to the whole range of pollutants from Crude oil to Heavy Fuel Oil although in low ambient temperatures (winter weather) the viscosity of the heavy fuel oil needs to be lowered by the introduction of heat. In the Pilot model depicted in Fig. 29 this is effected by feeding hot water into the suction branch and by supplying hot waterto the jet as shown. Means of supplying heat to a full scale installation are depicted in Fig. 4.

Preferred forms of my device in the dispersal mode are believed to have the following advantages:viz: (1) The chemical is introduced only to oil which is already emulsified with sea water and chemical is, therefore, not wasted on sea water which does not contain oil particles.

(2) In open waters the emulsion can be discharged via a hose hanging vertically beneath the device to a point some distance below the sea surface and thereby inhibit the buildup of chemical con cxentrations in the upper layers of the water.

(3) In dealing with oil pollution in inshore waters the emulsion can be discharged via a lightweight hose laid on the seabed to a position offshore and in the main tidal current thereby preventing possible ecological damage from high concentrations of chemical in shallow waters.

(4) In dealing with heavy fuel oil etc., which are difficult to emulsify at low ambient temperatures heat can be introduced to the device in the form of steam or hot water and thereby reduce the viscosity of the entrained fuel oil to the point at which it readilyforms an emulsion.

Claims (34)

1. A method of removing oil from the surface of a body of water which comprises impacting a fluid downwardly on the surface of a body of water to force oil to a position below the surface and causing it to be entrained by current flow into an inlet to a duct, and pumping the resulting oil/water mixture to a desired location.

2. A method according to Claim 1, wherein at least part of the pumping is effected by an educator.

3. A method according to Claim 2, wherein the eductor is powered with water from the body of water being treated.

4. A method according to Claim 1 or 2, which comprises collecting the oil/water mixture and allowing the oil and water to separate out.

5. A method according to Claim 2 and 4, wherein the eductor is powered with water separated from the oil/water mixture.

6. A method according to any one of Claims 1 to 5, wherein the fluid is water and an oil dispersant material is added thereto.

7. A method according to Claim 6, which comprises discharging the oillwater mixture into the body of water at a substantial depth below the surface thereof, or in preselected tidal currents therein.

8. A method according to any one of Claims 1 to 7, which comprises heating the fluid before it is impacted on the surface of the body of water.

9. A method according to any one of Claims 1 to 8, which comprises heating the water/oil mixture as it is indrawn into the duct.

10. A method according to any one of Claims 1 to 9, which includes the step of discharging the oil/water mixture into a collecting tank, allowing the oil to settle out, and removing the water.

11. A method according to Claim 10, in which a plurality of tanks in a conventional oil tanker are used.

12. A method according to any one of Claims 1 to 11, wherein a boom or booms is used to control the location and size of the oil slick.

13. A method according to Claim 1, substantially as herein described with reference to the accompanying drawings.

14. A device for removing oil from the surface of a body of water comprising: a) a fluid transfer line with (i) an inlet for positioning below the surface of the body of water; (ii) an outlet for discharging fluid at a desired location; and (iii) pump means for indrawing water from the vicinity of the inlet and transmitting it to the delivery end; and b) a fluid delivery circuit for directing fluid at the oil bearing surface from above and in a direction towards the said inlet with sufficient force such that, in use, floating oil will be driven below the surface of the water into the vicinity of the inlet and a resulting mixture of said driven oil and water will be indrawn into the fluid transfer line.

15. A device according to Claim 14, wherein the pump means comprises an eductor.

16. A device according to Claim 15, wherein the fluid delivery circuit includes a branch for supplying drive fluid to the educator.

17. A device according to any one of Claims 14to 16, wherein the fluid delivery circuit is adapted to deliver water directly from the body of water to be treated.

18. A device according to any one of Claims 14to 17, wherein the fluid delivery circuit includes controllable jets for directing fluid at high pressure to the surface of the body of water to be treated.

19. A device according to any one of the preceding claims, including at least one bouyancy tank for supporting the device in a body of water.

20. A device according to any one of Claims 14 to 19, adapted to be suspended in a body of water by a crane or the like.

21. A device according to any one of the preced ing claims, wherein the fluid delivery circuit includes a heater for raising the temperature of the fluid to be delivered.

22. A device according to any one of the preced ing claims including steam injection nozzles arranged at the inlet of the fluid transfer line for injecting steam into a fluid stream entering the inlet, and means for connecting the nozzles to a steam supply.

23. A device according to any one of the preceding claims including inlet means in the fluid delivery circuit connectable to a supply of oil dispersant material, for metering dispersant into fluid flowing through the said fluid delivery circuit.

24. A device for removing oil from the surface of a body of water substantially as described with reference to the accompanying drawings.

25. A system for recovering oil from the surface of a body of water, which comprises a device according to Claim 14, in combination with at least one collecting tank for an oil/water mixture, for receiving an oil/water mixture discharge from the outlet of the fluid transfer line.

26. A system according to Claim 25, wherein the collecting tank(s) is or are on-shore settling tank(s).

27. A system according to Claim 26, wherein the outlet from the fluid transfer line is located at or near the bottom of the tank.

28. A system according to Claim 25, wherein a plurality of collecting tanks are provided by a conventional oil tanker.

29. A system according to Claim 28, wherein the tanks are interconnected by a pipeline system routed from the bottom of at least one tank to the top of another tank, and from the bottom of said another tankto a pump for discharge overboard or, if the pump means is an educator, to the drive nozzle of said eductor.

30. A system for dispersing oil in a body of water on which the oil is floating, comprising a device according to Claim 23, in which the fluid transfer line is adapted for location of the outlet at a substantial depth in the body of water being treated, a reservoir for an oil dispersant material, and a supply line from the reservoir for connection to the inlet means in the fluid delivery circuit.

31. A system according to any one of Claims 25 to 30, and further including a boom or booms for controlling the spread or drift of an oil slick.

32. A system according to Claim 30 when appendantto Claim 16 or 17, and including a plurality of said devices operatively connected to said oil tanker.

33. A system according to Claim 25, substantially as herein described with reference to the accompanying drawings.

34. An oil dispersing system, substantially as described herein with reference to the accompanying drawings.