TECHNICAL FIELD

This invention relates to a method of, and apparatus for, collecting material from the surface of a substrate, particularly the recovery of viscous fluids and more particularly, but not exclusively, concerns a method of, and apparatus for, recovering heavy oil fractions from the surface of bodies of water and beaches.

BACKGROUND ART

Apparatus in many different forms has been proposed for recovering floating oil fractions of low viscosity from bodies of water. One form of such apparatus is based in the use of fibrillated oleophilic/hydrophobic materials such as polypropylene. Another form of the apparatus functions by attempting to "skim" floating oil from the water on which it floats.

The previously proposed apparatus, however, is generally found to be unsuitable for the recovery of the viscous heavier oil fractions and water-in-oil emulsions such as the so-called "chocolate mousse".

An object of the present invention is to provide apparatus for recovering viscous fluids of gravities ranging from 25 API downwards (2000 Cst. real viscosity upwards, and 0.90 S.G. upwards) .

DISCLOSURE OF INVENTION

According to the present invention, there is provided a method for collecting material from the surface of a substrate, characte ised by the steps of: i) bringing a pick-up portion of a first member of a collection apparatus into contact with the material in a

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pick-up zone, the portion defining a multitude of apertures, said step causing the material to be collected to enter the apertures; ii) moving the pick-up portion through a support zone from the pick-up zone to a discharge zone; iii) providing a second member of the collection apparatus for co-operating with the first member in the support zone to resist discharge of the material from within the apertures of the pick-up portion while it is within the support zone; and iv) engaging the apertures with discharge means in a discharge zone to expel the material from the apertures.

According to a second aspect of the present invention there is provided apparatus for collecting material from the surface of a substrate, characterised by a first member having a pick-up portion defining a multitude of apertures and movable from a pick-up zone in which the material may enter the apertures by contact of the first member with the material, through a support zone to a discharge zone and from the discharge zone back to the pick-up zone, a second member which co-operates with the first member in the support zone to resist discharge of material from the apertures in the support zone, and discharge means in the discharge zone for engagement with the apertures in the discharge zone to expel the material from within the apertures.

The material will normally be a viscous fluid such as petroleum-based oily liquid or mousse, or a heavy oil liquid fraction, but need not be. For example, the material might be solid, floating debris or bas«d on an animal fat, vegetable oil, igolasses, sludge or cement.

4 The apparatus has particular use for recovering heavy oil and oil-based fluids from bodies of water, including lagoons and maritime waters, and from beaches. It is particularly suited to the recovery of fluids which in the context of oil have very high viscosity and especially

those which are found in a cold environment, examples being crude oils which have become thick as a result of prolonged weathering, and beach deposits of heavily emulsified oil fractions.

Preferably the apertured first member is a belt, and also an endless loop, most preferably an endless chain belt provided as part of an elongate chain belt assembly. In this last case, it is preferable that a lower run carries the viscous fluid from the pick-up zone to the discharge zone, and the second member is preferably a tray located ^' beneath the lower belt run of the belt assembly. The discharge means preferably comprises a discharge roller which may be a drive roller of the belt, having a plurality of projections on the cylindrical surface thereof which engage in the apertures of the belt to expel the fluid therefrom. In such a case, the discharge means may comprise in addition a scraper blade which bears on one face of the belt.

Normally, the loop of belt is advanced around a main roller at the discharge zone end of the loop where viscous fluid is discharged from the belt, and an idler roller at the pick-up zone end of the belt where viscous fluid fills the apertures of the belt. Thus successive portions of the belt enter the pick-up zone, carry oil to the discharge zone and then return to the pick-up zone. Although the main roller will usually constitute both a belt drive roller and a discharge roller, it need not provide these functions.

At the pick-up end of the belt assembly, it may be convenient to provide a pick#-up section of the endless belt assembly between the idler roller and a further roller intermediate the idler and main rollers, the pick-up section being specially adapted for a particular recovery task. Thus for recovery of floating oil, the pick-up section is advantageously inclined to the remaining major portion of the length of the assembly, in

that the plane containing the rotational axis of the intermediate roller and the idler roller is at an angle with the plane containing the rotational axis of the intermediate roller and the main roller. The plane of the pick-up section may lie in the surface of the body of liquid or at a preferred, small angle thereto for maximum efficiency in pick-up of viscous liquid by downward movement of the chain belt through the floating oil prior to entry into the support zone.

For recovery of viscous, oil-based liquids from water bodies, it is convenient to provide the endless belt in the form of a cellular steel belt such as a so-called "honeycomb" belt as sold by ϋ ec-Boydell (Belting) Limited of Wolverhampton, County of West Midlands, England. In this application, the apertures in the belt can have a width, in the plane of the belt, a range of from 4 to 6 cms. The width of the belt is conveniently in a range of from 70cms. to 2m. One useful belt thickness is 2cm.

It may be convenient to provide for adjustment of the distance between the main and idler rollers of the endless belt assembly, so that the belt assembly may be moved between a stowed disposition where the distance between the rollers is small and an operational disposition where the distance between the main and idler rollers is at or near a maximum within the range permitted. One way of achieving this adjustment of distance is to provide for the belt to be doubled back over a pair of jockey rollers at some point along one or other of the belt runs between the main and idler rollers. Then, the main and idler rollers may be moved towards and away from one another on sliding frame members which provide a corresponding movement of the jockey rollers so that the belt remains taut.

Apparatus according to the invention may be mounted on a road-going vehicle. In such a case the apparatus may be

suspended from one or more of the arms which pivot on a frame on the vehicle. This frame can be an integral part of the vehicle or a demountable frame for fixing on any available vehicle as circumstances require. It may be useful for the frame to be mounted to, or to comprise, a turntable so that the apparatus can be deployed in a range of different positions while the vehicle remains stationary. In any case, it may be appropriate to provide on the vehicle or on to the frame one or more load-supporting legs to prevent damage and provide additional stability to the vehicle when the apparatus is in use.

BRIEF DESCRIPTION OF DRAWINGS

Reference will now be made by way of example to the accompanying drawings, in which:

Figure 1 is an elevation of a first embodiment of apparatus according to the invention mounted on the trailer of a road-going vehicle showing, schematically, the apparatus in its stowed position, inboard of the trailer;

Figure 2 is an elevation similar to Figure 1, showing the apparatus deployed outboard from the rear of the trailer for recovery of oil from below the level of the trailer from the surface of a lagoon;

Figure 3 is an elevation similar to Figure 1 and 2 showing the belt assembly of the apparatus deployed outboard of the trailer and over a raised bank of a lagoon;

* Figure 4 is an elevation similar to Figures 2 and 3 for indicating certain operating dimensions of the illustrated first embodiment;

Figure 5 is an elevation similar to Figure 1 showing in more detail certain elements of the apparatus, including

the belt assembly and transport arms therefor;

Figure 6 is a plan view of part of the chain belt of Figure 5, with part of the width of the belt not shown, for economy of presentation;

Figure 7 is an end elevation of a drive and discharge roller for the belt shown in Figure 6 and taken transverse to the rotational axis of the drive roller;

Figure 8 is a diametral section of the roller of Figure 7, with a middle section cut away, again, for .ejconomy of visual presentation;

Figure 9 is a plan view of a second embodiment of the invention, which is apparatus mounted on a skid unit and carried on a barge;

Figure 10 is a plan view of a third embodiment of the invention, which is apparatus mounted on a barge;

Figure 11 is a plan view of a fourth embodiment of the invention, which is apparatus which includes a catamaran hull;

Figure 12 is a graph showing the effect of belt speed V on the rate R of recovery of oil in use of the first embodiment; and

Figure 13 is a graph showing the variations of the rate R of recovery of oil in use of the first embodiment with changes in oil viscosity eta.

MODES FOR CARRYING OUT THE INVENTION The apparatus shown in Figures 1 to 8 comprises a tandem axle trailer 10 which carries a turntable 11 which serves as a frame for oil collecting apparatus according to the invention. The apparatus comprises an endless belt

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assembly 12 suspended from the turntable 11 by a pair of arms 13, one each side of the belt assembly 12, which arms pivot at their fixed ends on trunnions 14 on the turntable

11 and carry at their free ends sling members 15 connected at their lower ends to the belt assembly 12 close to its centre of gravity. The belt assembly has a fixed frame 60 and a mobile frame 61 which slides on the fixed frame 60 between the disposition shown in Figure 1 and that shown in Figure 3.

When the apparatus is to be used, the turntable is rotated o through 180 from the Fig 1 position to that shown in Figs. 2, 3 and 4.

As shown in Figure 2, the arms may extend outwardly of the turntable 11 and support the belt assembly in a position where a lower end 16 thereof contacts the surface 17 of a water body 18 in a recessed lagoon area 19. An upper end 20 of the belt assembly 12 then overlies the area of the turntable 11 adjacent the trunnions 14.

Between the two arms 13 and beneath the upper end 20 of the belt assembly 12 is an oil-collecting tank and oil/water separator 21. A diesel engine prime mover 22 on the turntable 11 provides power to a hydraulic oil pump 23, and a transfer pump 24 which is for driving oil from the separator 21 to a storage location off the trailer 10. Water entrained with the oil can be separated from the oil, and recovered oil can be injected with an emulsion breaker or viscosity reducer by means familiar to those skilled in the art.

The turntable 11 is rotated Relative to the trailer 10, in the conventional manner, and power for such rotation may be drawn from the prime mover 22.

Comparison of Figure 1, 2 and 3 will show that the length of the belt assembly is variable. This variation is acheived by sliding movement of the mobile frame 61 on the

the fixed frame 60, as will be explained hereinafter. Power for such an operation is derived from the hydraulic pump 23. In the stowed position of Fig 1 the length is a minimum. As in Fig 2 the length may be progressively 5 increased, in use, as the level of liquid falls with recovery thereof, from a starting position S to a finishing position T, shown chain-dotted.

It will also be seen from Figures 1 to 3, that the arms 13 0 have been swung through an arc to carry the belt assembly inboard and outboard of the trailer 10. This operation is performed by a pair of hydraulic piston and. cylinder actuators 42 (see Figure 5) driven by the pump 23, as more fully described below. 5

A pair of support legs 27 assists the trailer to bear the weight of the arms 13 and belt assembly 12 in their outboard, working position. The legs 27 are deployed manually but use of the hydraulic power drawn from the 0 pump 23 is a feasible alternative.

Referring to Figure 5, the belt assembly 12 incorporates a terminal pick-up section 26 which is set at an angle alpha to the remaining length of the belt assembly 12 and a 5 small angle beta to the surface 17 of liquid in the lagoon.

In Figure 5 at the lower, pick-up end 16 of the belt 28 is an idler roller 31 and a pair of intermediate rollers 32 30 and 33, which are also idler rollers. The belt 28 has an upper run 34 which passes between the rollers 32 and 33 and is guided by the roller 32 around an arc of its circumference determined by angle alpha. A lower run 35 of the belt passes over a corresponding arc of the roller

35 33 and runs directly up the length of the belt assembly to a main, drive and discharge roller 36 at the upper end 20 of the assembly. In contrast, the upper run 34 passes from the discharge roller 36 over a first jockey roller 37 and back over a second jockey roller 38 before passing to

40 the roller 32.

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The fixed frame 60 has a flat plate 63 on which the lower belt run 35 slides as it advances towards the drive and discharge roller 36. Contiguous with the plate 63 is a further flat plate 64 on the mobile frame 61 which extends to the region of the intermediate roller 33. The plates 63 and 64 slide on one another when the mobile frame 61 slides on the frame 60, and together constitute a tray beneath the lower belt run 35.

The jockey roller 37 is connected to the fixed frame 60 of the belt assembly to which the drive roller 36 is also fixed, so that rollers 36 and 37 stay spaced apart by a fixed distance. The jockey roller 38 is connected to the mobile frame 61 to which the rollers 31, 32 and 33 are also fixed, so that all the four rollers 31, 32 and 33 and 38 maintain fixed distances. from one another.

The mobile frame 61 is slidable on rails (not shown) on the fixed frame 60, in such a way that the intermediate rollers 32 and 33 can be moved towards and away from the discharge roller 36. In Figures 3 and 5, the distance between the these rollers is a maximum. When the mobile frame is moved towards the discharge roller 36 the jockey rollers 37 and 38 move apart from one another at the same rate as the rollers 33 and 36 move towards one another, so that the belt 28 remains at the same tautness at all times. The movement of the mobile frame relative to the fixed frame is effected by a hydraulic actuator (not shown) .

Figure 5 also shows, in more detail than Figure 1, the construction of the arms 13. Each of these is mounted on one of the fulcrums 14 by m^ans of a journal bearing 40. A short distance along each, of the arms 13 from the bearing 40 is a further journal bearing 41 at one end of a hydraulic actuator 42 is connected to the arm 13. The other end of the actuator is connected to the frame 11 by a further bearing 44. Thus, with the actuator 42 fully extended, the arm occupies the position shown in full

line in Figure 5, with the actuator part-extended, the assembly 12 arm can be brought into an alternative position 25, (shown chain dotted) and with the actuator fully retracted, the arm occupies the position shown in 5 Figure 1.

Figure 6 shows a construction of an endless cellular (or so-called "honeycomb") steel belt 28 used in the belt assembly 12 and constituting an apertured first member of

10 apparatus according to the invention. The belt is composed of a large number of steel strips 29 of interfitting, zig-zag, almost square wave, shape connected together by transverse rods 30 to provide a multitude of apertures 45. The tranverse edges of the belt, or

15 "selvedges", can be formed in a variety of ways. In Figure 6, each end is secured by a flat washer 46 and pin 47. The steel strips are 2cms wide and the pitch of the "square wave" zigzag form is lOcms.

20 Figures 7 and 8 show the form of the projections or "tooth form" of the drive and discharge roller 36. The roller has an array of teeth 50, arranged in discrete rings of twenty teeth spaced equally from one another around the circumference of the roller and in a plane transverse to

25 the rotational axis of the roller. The rings may be fabricated from a polyurethane material. The roller 36 is assembled by sliding the discrete rings 51 onto a roller core 52 and end plates 53 and 54 so that the rings abut one another along the length of the roller core and cannot

30 rotate relative to the core 52. The roller has a plurality of such rings, spaced along the length of the roller with a pitch of one-half that of the strips 29 of the belt 28, so that the tooth engages with each of the apertures 45 of the belt 28.

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The roller 36 has a shaft 55 secured by a flange 56 to the core 52 and by a flange 57 to the end plate 54. The end plate 53 has a splined boss 58 which receives a corresponding splined output shaft of an epicycle drive

gearbox (not shown) which extends into the hollow end of the roller 36 adjacent the end plate 53. The shaft 55 is carried in a journal bearing. The form of the teeth 50 is chosen to provide smooth entry and exit between the tooth and apertures of the belt 28 as the roller 36 rotates in use, together with occupation by the tooth 50 of as much as possible of the volume of the apertures as they pass over the roller 36. In this way viscous liquid is expelled from the apertures by the teeth.

It should be noted that the chain belt and discharge roller » are readily available in a wide variety of widths, so as to suit different applications of apparatus as required recovery rates eg from half tonne to 30 tonnes per hour.

In use of the device, the trailer 10 is parked in a convenient position and the legs 27 are deployed. The turntable 11 is rotated if necessary, and the belt assembly 12 is actuated to extend it from its transport length (see Figure 1) to its operational length (see Figure 2) . Then, the arms 13 are actuated to swing the belt assembly 12 outboard of the trailer 10 so that the lower end 16 of the assembly contacts the surface 17 of the body of liquid 18 from which floating oil is to be collected.

The roller 36 is actuated to rotate in an anti-clockwise direction (as seen in Figure 5) . The lower run 35 of the belt 28 then moves in a direction from the roller 31 to the roller 33, which movement results in apertures of the belt in the pick-up zone, in effect, the lower run 35 in the terminal pick-up section 26, dipping into the floating oil, thereby causing liquid to enter the apertures so that they become full of oil. The oil is carried around the intermediate roller 33 where there is convergent pincer movement between the belt and the plate 64, and the belt 28 so engages the plate 64 that viscous material is trapped in the belt apertures by the plate 64 and oil is i

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transported in the apertures to the discharge roller 36 along the lower belt run 35. During such transport, the plates 63 and 64 support the apertured belt and prevent oil from discharging from the oil-filled apertures of the belt 28. At the discharge roller 36 oil is discharged out of the apertures into the oil/water separator 21. A doctor blade or scraper blade 59 is provided to assist the discharge action of the teeth 50 in removing viscous material from the belt 28.

The plates 63 and 64 constitute the second member of the apparatus in accordance with the invention and the support zone extends from the lower edge of the plate 64 to the upper edge of the plate 63.

Comparison of Figures 2 and 3 will show that the angle between the pick-up section 26 and the remaining length of the belt assembly 28 is different. It will be appreciated that there may be advantage in some applications of the apparatus to provide means for adjusting the angle alpha in order to maintain angle beta constant or near constant with varying water levels.

As an alternative to the use of a drive and discharge roller, it may be convenient to discharge material from the belt 38 just before it reaches a drive roller, for example, by means of a separate discharge roller or with jets of steam directed at the apertures in the belt.

By way of example, one set of dimensions as shown in

Figure 4 are given below, for a trailer mounted collection apparatus with an overall length of 5.1 metres and weight of 2600 Kg.

AH Maximum operating height above ground level 1.1m

BH Maximum operating depth below ground level 1.46m

CJ Maximum outreach 4.4m

DJ Minimum outreach 1.64m

The difference GH between a trailer-mounted and corresponding skid-mounted unit is 0.6m.

The embodiments of Figures 9, 10 and 11 correspond with the above described embodiment but for differences in the situation in which they are mounted, which will be apparent from the drawings to those skilled in the art. Like references are accordingly used to identify corresponding elements of the embodiments.

In Figure 9, the barge 90 on which the recovery apparatus is mounted provides capacity for storage of recovered oil. It is intended for use in harbours, esturies and cargo terminals. It can be self propelled or, more usually, propelled by. a workboat or launch. It has a debris collection device 91 to prevent damage to the recovery apparatus 12.

In Figure 10, the recovery apparatus 12 is deployed over the side of the vessel 92 such as a supply boat or tug and hauled inboard and stowed when not in use. It is powered by the hydraulic system of the host vessel.

In Figure 11, a large recovery apparatus 12 is based in the hull of a catamaran having twin hulls 93 and 94, but the apparatus is demountable to enable the vessel to be used for other duties. A debris collection device 91 is again provided.

The data of Figures 12 and 13 are relative to the first embodiment described above. *

Figure 12 derives from recovery of crude oil originating from a North Sea oil field. The data of Figure 13 apply to operation with the chain belt moving at a speed of 12 metres/min.

The three plots represent three different depths of floating oil layer, as stated on the graphs.

While the above description with reference to the illustrated embodiment of the invention concerns recovery of viscous fluid from the surface of a body of water, it will be appreciated that the present invention can also provide apparatus for recovering a viscous fluid from other locations and, in particular, from any reasonably flat solid surface. For example, it may be employed for recovery of oil deposits on a beach.

For lifting oil from beaches the apparatus illustrated can be modified by providing a support to maintain the leading edge of the plate 64 just above the surface of the beach, and a screen to prevent passage of shingle, jetsam and other coarse debris into the support zone of the machine. The support can be a wheel, roller or a skid which moves over the surface of the beach. The screen and support may be provided as a detachable nose piece, especially where the apparatus is intended as a multi-purpose machine.

The apparatus of the invention need not be a versatile, transportable machine as hereinbefore described but may instead be a special purpose, permanently installed machine, and may be smaller than the illustrated machine, with a belt run of a length which is not adjustable to the same extent at all.

it is not essential to employ an endless belt. For example, reciprocatory movement of an apertured mat or net between a disposition where viscous material is taken up to a disposition where it is- discharged from the apertures may be more convenient in special applications of the invention.

INDUSTRIAL APPLICABILITY

It will be apparant from the foregoing description that the invention is useful for recovering viscous fluids. The recovered fluids may be valuable, but the saving of loss and damage which would occur if they had not been recovered is likely to be even more important. The existing methods of recovery of liquids of low viscosity are of little use in treating high viscosity fluids. The effectiveness of the present invention does not depend upon chemical action the rate of which is temperature dependent, and so will find application in low temperature environments. Specific applications have been described above.

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