CA1147666A - Method and apparatus for removing contaminating liquids floating on water - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE

Apparatus for lifting oil off the surface of water comprises a vessel which is capable of sweeping back and forth through the floating oil. The vessel is equipped with oil catching and storing equipment and also with an oil lifting mechanism having a plurality of pickup discs arranged in sets each rotatable about a horizontal axis extending transversely of the mechanism. This lifting mechanism is operated to move each set of pickup discs in turn between a loading position at least partly immersed in the water and a discharge position adjacent the oil catching and storing equipment. A drive for each set of pickup discs rotates the discs during operation of the mechanism at a first speed in the loading position to coat the discs with oil and at a second speed in the discharge position so that at least a portion of the oil adhering to the discs is thrown off by centrifugal force into the oil catching and storing equip-ment.

Description

This lnven-tion rela-tes to an apparatus for clean-ing up an oil spill in a harbour or elsewhere.
The task of clearing a harbour of a contaminating substance such as oil is an extremely difficult one par-ticularly when the sea conditions are poor or the -tem-perature is low as so often appears to be the case. One machine employed for this task is equipped with an endless fabric belt which is mounted at the bow of a boat to incline downwardly into the water. sy rotating the belt, oil is lifted up and transferred to a location aboard the boat where it is scraped off the belt and deposited in a holding tank. Another device suggested for the same task is equipped with a multitude of ver-tically standing metal di.scs which are mounted in a float serving as an intake for a pumping system. The discs are rotated to pickup the oil but again the oil must be scraped off the discs with a result that the oil discharging problem is only slightly easier than is the case where an endless fabric belt is employed.
The present invention overcomes the disadvantages of the above mentioned oil recovery systems by providing apparatus which is equipped with fabric discs. Such pickup members have been found best suited for lifting the oil off the surface of the water and the flexibility of such a material has a number of secondary advantages as well~ For example, the flexible discs can operate with reasonable effectiveness when the water surface is roughened or there is floating debris or ice to contend with. The discs form part of a conveyor which operates continuously to raise oil off the water surface and into a barge. When partly immersed t7'~66 in the water, the discs are ro-tated slowly to ensure a maximum oil load. The oil is discharged from the discs aboard the barge by rotating them at a speed sufficiently hiyh to throw off the oil by centrifugal force. If neces-sary, hea-t and a cleaning fluid is applied to the rapidly spinning discs to assist in -the discharge of the oil.
More specifically, according to the present invention, there is provided apparatus for recovering oil floating on a body of water which comprises a vessel movable over the water through the floating oil, said vessel being equipped with oil catching means, and oil lifting mechanism mounted on the vessel and including a plurality of pickup discs arranged in sets each rotatable about a horizontal axis extending transversely of the mechanism, means for operating the oil lif-ting mechanism to move each set of pickup discs in turn between a loading position at least partly immersed in the water and a discharge position adjacent the oil catching means, and drive means for rota-ting each set of pickup discs at a first speed in the loading position whereby the discs are coated with oil and at a second speed in the discharged position whereby at least a portion of the oil adhering to the discs is thrown by centrifugal force into -the oil catching means.
In drawings which illustrate a preferred embodi-ment of the invention, Figure 1 is a schematic side elevational view ofoil recovery apparatus constructed in accordance with the present invention, Figure 2 is a schematic plan view of the appara-7~6~;
tus, Figure 3 is a plan view of a portion of a conveyorchain assembly of the apparatus, Figure 4 is an enlarged vertical section taken on the line 4-4 of Figure 2 showing one of the driven reels of the conveyor, Figure 5 is a view similar to Figure 4 but showing an idler wheel of the conveyor, Figure 6 is an enlarged vertical section of a tunnel structure of the appara-tus showing a cross member of the conveyor supported thereby, Figure 7 is an enlarged vertical section of a housing provided on each cross member, Flgure 8 is a schematic side eleva-tional view showing drive means of the apparatus, Figure 9 is a plan view of the drive means.
The apparatus 10 primarily is intended for use in cleaning up an oil spill in a harbour or elsewhere and therefore a suitably constructed barge 12 is used to carry the present apparatus. Preferably, the barge is self propelled so that it can move back and forth across the harbour as is required to gather in the floating oil and lift it off the surface of the water. Apparatus 10 is provided with an oil lifting mechanism which is shown to comprise a conveyor 14. The conveyor operates to transfer oil from the water to catching means 16 aboard the barge where the oil is temporarily held until it can be trans-ferred to a shore facility. The conveyor 14 is carried beneath a hood 18 which is mounted on the barge to project forwardly of the bow. The floating oil normally forms only a relatively thin layer spread over a large area so the present apparatus includes sonic sweeping equipment 20 which serves to gather the oil into a pool beneath the hood where it can readily be picked up by the conveyor.
The sonic sweeping equipment generally indica-ted at 20 relies mainly on acoustic energy to propel the float-ing oil towards the path of travel of the barge. This type of sweeping action is disclosed in Canadian Patent No.
1,067,709 granted to this applicant on November 12th, 1979 for an invention entitled MEANS AND MET~IOD FOR SWEEPING
MATRRIAL FLOATING ON WATER USING VI~RATION ENERGY. In the present invention, the equipment 20 will be seen -to be provided with a pair of arms 22 the rearmost ends of which are mounted on laterally projectin~ pivots 23 secured to the front end of the hood 18. The arms curve downwardly from their pivots and then diverge outwardly from the hood to generally horizontal sections 24 of the arms which are interconnected by hinges 25. A float 26 is secured beneath each section 24 and the buoyancy of these floa-ts is such that the several sections are supported on or at least just below the surface of the water. Depending from each float 26 is a sound producing device or transducer 27. A suitable electric circuit, not shown, connects the several trans-ducers to equipment aboard the barge such as an oscillator and a source of alternating current. This equipment is operable in the manner described in detail in Canadian Patent No. 1, 067,709 to energize the several -transducers whereby ultrasonic waves are generated. The transducers are aimed upwardly towards the water surface and also inwardly of the arms so that the sound waves generated produce at the surface an acoustic force which reacts with the air above the oil covered surface and provides a sweeping action as taught by the above mentioned patent. This vibrational energy serves to sweep the oil between the arms which also act as sweeps and so that the oil collects as a pool beneath the hood 18 and in the pa-th of travel oE the conveyor 14 as the barge moves ahead.
The conveyor generally indicated at 14 comprises a number of horizontal shafts 30 one of which is shown in detail in Figure 3. Each of these transversely extending shafts has opposite ends journalled in bearings 32 which are mounted in hollow floats 33. The shafts each rotatably extend through a cylindrical housing 35 which is equidis-tantly spaced between the floats. The cylindrical floats 33 and the housing 35 on adjacent shafts are connected togetherby lengths of cable 36 so that the spaced apart shafts and associated parts plus the mul-tiple connecting cables form an endless assembly 38 comparable to a conventional conveyor chain. Between the floats and the housing, each shaft has enlarged cylindrical portions 40 on which two transversely spaced sets of discs 41 are mounted. These discs are formed of annular bands of a suitable woven fabric to which oil will readily adhere and the fabric is a type which will resist penetration by water. As shown best in Figures 4 and 5, the fabric discs are secured to the shaft portions 40 by hollow hubs 42 and preferably the flexible fabric is stiffen-ed to a suitable extent by radial strips 43 formed of the same fabric material.

The endless assembly 38 of the conveyor is mounted in pairs of drive and driven reels indicated at 50 and 51 respectively. In order -to support -the assembly 38, the hood 18 is provided with a horizontal top wall 53 and vertical side walls 54. Figure 4 shows one of the reels 50 as having a spindle 56 mounted in a bearing 57 which is carried by one of the side walls 54 of the hood. This reel has circular flanges 58 and 59 in which circumferentially spaced notches 60 and 61 respectively are formed. The cylindrical bearings 33 in which the transverse shafts are rotatably mounted are received in the notches 60 and the cylindrical housing 35 enters the notches 61 as shown in Figure 4. Another iden-tical reel 50 is similarly moun-ted on the other side wall 54 of the hood in transverse alignment with the above described driven reel but, for convenience, this other driven reel is shown only by dotted lines in Figure 1.
A pair of the reels 51 are also mounted in -the side walls 54 of the hood where the rearmost end oE the top wall 53 extends over the deck of the barge. Figure 5 shows one reel 51 as having a spindle 63 journalled in a bearing 64 secured to a side wall 54 of the hood. Circular flanges 20 65 and 66 on the reel 51 are provided with a tooth forming arrangement of notches 67 and 68 respectively, the notches being adapted to receive the bearings 33 and an end part of the housing 35. Thus, the chain like assembly 38 is trained over the pairs of reels 50 and 51 much as a conveyor chain is trained over drive and drlven sprockets. The reels 50 are the driven members in this instance while the reels 51 are idler members.
In order to drive the pair of reels 50 and operate the conveyor, the apparatus 10 is provided with means which 30 is generally indicated at 70 in Figures 1, 2 and 4. The :L~

operating means 70 is shown to comprise an electric motor 71 which is supported on top of the hood beneath a suitable cover 72. Motor 71 has a reduction gear connecting the drive shaEt of the motor -to two aligned shafts 73 which are journalled in bearings 74 so as to extend across the hood and project beyond the side walls 54. Chain and sprocket drives 75 connect the overhanging ends of the shaf-ts 73 to the spindles 56 of the pair of reels 50. Preferably, the drives 75 are enclosed within protective covers 76 secured to the side walls of the hood. The motor 71 is connected by appropriate circuitry to a suitable source of power aboard the barge where a swi-tch is located to allow a crew member to control the motor.
Operation of the motor 71 rotates the endless assembly 38 in a clockwise direction as used in Figure 1 where it will be noticed the lower run of the assembly is quite slack, that is, it hangs down below the hood 18 to move across the surface of the water. The floats 33 provide a certain amount of buoyancy at this time so that the flexible discs 41 normally are not totally submerged. Oil adheres to the discs in this location which will hence-forth be referred to as the loading position of the pickup discs. The upper run of the assembly 38 is supported by the drive and idler reels 50 and 51 with very little slack and the upper run is further steadied and held taut by guide rails 78 and 79 which are shown by dotted lines in Figure 1.
Portions of these rails are secured to inner surfaces of the hood in position to slidably receive the floats 33 and housings 35 as the endless assembly 38 is rotated. It is along the upper run where oil is thrown off the flexible ~7~6~i discs and, at this discharge position, the oil catching means 16 is located.
As shown in Figure ~, the means 16 comprises a tunnel like structure 80 located below the top wall 53 of the hood between the driven and idler reels. The guide rails 78 and 79 extend through and are partly supported by this open ended structure to slidably receive the floats 33 and housings 35. The housings move through a tunnel 81 in that structure and the sets of discs 41 travel through tunnels 82 which are in communication with storage chambers 83 and 84 provided in -the structure 80. Oil thrown off the discs within the tunnels flows first into the chambers 83 and then into the chambers 84 where the oil is drawn off through pipes 85. These pipes extend alongside the hood to the stern oE the barge 12 where they connect with a holding tank (not shown) carried by the barge. Suitable pumping and control devices are provided to allow oil collected in the storage chambers 84 to be moved through the pipes to the holding tank.

The flexible discs 41 are rotated about the axes of their transverse shafts as they travel around the circum-ference of the conveyor. Rotation of the discs is Eairly slow along the lower run of the conveyor but it is necessary to spin the disc quite rapidly when they are in the dis-charged position in order to throw off the oil by centri-fugal force and therefore the apparatus 10 is provided with a two speed drive means generally indicated at 90. In Figure 7, the drive means 90 will be seen to comprise a turbine wheel 92 secured tp each shaft 30 within the housing 35. The barge is equipped with a steam generator 93, see ~76~

Figures 1 and 2, the generator delivering controlled amounts of suitably pressuri~ed steam through pipes 94 to a rota-table manifold 95 which is shown schematically i.n Figures 8 and 9. The manifold is located between the drive and idler reels in about the center of the endless assembly 38.
Flexible tubes 96 are connected at one end to the maniEold and at their opposi-te ends these tubes are connected by couplings 97 -to an endless tube 98. At intervals of its length, a tube 98 is connected by an inlet 99 to each of the housings 35. Steam enters each housing 35 through the inlet 99 and travels through a port 101 (Figure 7) into a chamber 102 in which the turbine wheel 92 is located. A small outlet 103 vents each chamber 102 to atmosphere.
Such a steam system provides the power which enables the drive means 90 -to rotate the discs at the two required speeds. These two speeds are regulated automa-tically by a control arrangement which is shown best in Figure 7 as comprising a valve plate 106 which is slidably supported by parts 107 of each housing 35 for limited reciprocatory movement. A piston 108 is provided on the plate to reciprocate in a cylinder 109 formed in the housing.
The valve plate extends across the port 101 and the plate is provided with an end slot 110 as well as with longitudinally spaced openings 111 and 112. Cylinder 109 is connected by ducts 114 and 115 to vertical cylinders 116 and 117 which project through the top of each housing. These vertical cylinders are fitted with plungers 118 and 119, the lat-ter plunger being urged outwardly by a spring 120. A quantity of oil which is indicated at 121 fills the cylinder 109, the _g~

7~

ducts 114 and 115, and the cylinders 116 and 117 beneath the plungers in those cylinders. On the underside of -the structure 80, there is a cam track 12~ located between -the driven and idler reels and this ~am ~rack is disposed in -the path of travel of the plunger 118. Another cam track 125 is attached to the ~Inderside of the structure 80 in the path of travel of the plunger 119. This plunger 119 is fitted with an adjusting screw 127 which has sliding contact with the track 125. The two cam tracks are longitudinally spaced apart above the upper run of the conveyor so as to be engaged by an appropriate intervals by the plungers. The arrangement is such that pressurized steam reaches the chamber 102 through the port 101 in which the opening 111 is now located to drive the turbine wheel at a speed of jus-t a few revolutions per minute whenever each housing 35 is outside the tunnel structure 80, -that is to say, when the housing forms part of the lower run of the conveyor chain assembly. The discs are thus rotated slowly particularly when in the loading position where they are partly submerged in the water. The slow rotation of the discs ensures that the entire surface of the fabric is coated with oil before they move up out of the water and under the forward end of the hood.
As a set of discs 41 which have been coated with oil approaches the forward end of the structure 80, the plunger 118 is depressed by its cam track 124 to force the valve plate 106 to a position where the slot 110 is aligned with -the port 101. A greater amount of steam is now able to enter the chamber 102 through the port in which the slot 110 ~'7~

is now located and, as a resultl the turbine wheel 92 is driven to spin the oil loaded se-t of discs at a speed sufficient high to throw off oil by centrifugal force. This thrown off oil is caught by in-terior parts of the struc-ture S 80 and is collected in -the chambers 83 eventually to reach the chambers 84 and be drawn off through the pipe 85.
Each set of discs is rid of most of the adhering oil in this manner and, as the discs approach the idler wheels 51, the rapid spinning is reduced to the former slow rotation by the above described valve arrangement. This is achieved when the plunger 119 is depressed by the cam track 125 thus forcing the cam plate 105 back to the Figure 7 position. The limited amount of pressurized steam which now reaches the turbine wheel 102 through the port 101 and opening 111 is sufficient only to keep the discs rotating a-t the desired slow speed which is maintained as the unloaded discs travel along the lower run on the conveyor to pick up more oil.
Referring now particularly to Figures 7 and 10, each shaft 30 will be seen to be tubular so as -to have a bore 130 which extends through the cylindrical portion 40 of the shaft. The bore is in communication with the hollow hubs 42 by virtue of circumferentially spaced apertures 132.
Arranged around the hubs are a number of nozzles 133 which are directed towards the annular bands of the adjoininy discs. The shaft has other relatively large apertures 135 located within the housing 35 as shown in Figure 7 so that the nozzles 133 can be supplied with some of the steam which is delivered to the housing 35 to drive the turbine wheel.
A suitably small proportion of the live steam is dlverted into the interior of each housing 35 at the time the discs adjoining that housing are spun rapidly to throw off oil. The piston 108 is moved to the right (Figure 7) to shift the slot 110 across the por-t 101 and this movement also places the opening 106 in the valve pla-te wi-thin a port 137 provided in the housing. Steam then reaches the nozzles 133 through the apertures 135, bore 130 and apertures 132 to discharge against the discs. Thus, -the apparatus 10 is provided with means for applying heat to the pickup discs 41 in the discharge position whereby to reduce adhesion of the oil.
The flexible discs which are discharged of most of their oil load by centrifugal force and are also steam heated to assist in this unloading can be cleared of mos-t of the remaining oil residue by khe application of a cleaning fluid. Preferably, a suitable solvent is used for thls purpose, the cleaning fluid being injected into the structure 80 through nozzles 140 whlch appear in Figure 6. The nozzles are mounted on top of the hood 18 to extend into the tunnels 82 through which the sets of discs must travel when in the discharge position. Hoses 141, see also Figure 2, connect the nozzles to a unit 142 provided on the barge 12 to supply so]vent under pressure. The cleaning fluid preferably is injected intermittently into the tunnel 8 in timed relation to the passing of the discs through those tunnels so as to lmpinge upon the steam heated discs and remove most of any oil which may be left clinging to the flexible discs 41. The injected solvent mixes with the recovered oil in the chambers 82 and 83 so as to be pumped into the holding tank where it can later by separated and 7~

reused. By this arrangement, the apparatus 10 is provided with means for directing a cleaning fluid at the pickup discs in the discharge position.
In operation, the present oil recovery apparatus is moved ahead at a reasonably slow speed -to advance on a floating oil slick. The diverging arms 22 oE the equipment 20 serve to some exten-t as booms which collect the floating oil in front of the advancing barge and, when the ultrasonic devices 27 are energized, the oil is propelled into a relatively thick layer immediately in front of the conveyor 1~. The conveyor, which is run continuously during a recovery operation, moves the rotating pickup discs progres-sively through the oil layer allowing the discs to become coated with oil. The floats 33 serve to keep at least the upper portion of the discs projecting above the oil layer and it is in thi.s region where most of the loading talces place. It may happen that debris or even small chunks of ice will strike the discs but, since they are flexible, no damage is done. The surface of the water may be roughened to some extent but this does not affect the pick up action of the discs. In point of fact, it may improve the action since the discs themselves adapt a wavey configuration most notable near the circumference of the discs and this appears to increase the amount of oil which clings to the fabric discs and subsequentl.y is lifted clear of the surface of the water.
The loaded discs s-till rotating slowly are raised and moved along the upper run of the conveyor which travels through the tunnel like structure 80. As previously mentioned, i6 the discs are spun rapidly when travelling through -the tunnels 82 to throw off most of -the clinging oll by cen-trifugal force. IIot steam is applied to the discs to raise the temperature of the oil and assist in the throwing off action. The application of solvent cleans the discs to the extent that -they can later lift a maximum amount of oil when the rotating conveyor again wipes them through the floating oil layer.
From the foregoing, it will be apparent the present oil recovery apparatus provides an effective means and method of picking up oil spilled in a harbour or else-where. The use of flexible discs as pick up members avoids the likelihood they will suffer the type of damage which might be inflicted on metal discs by floating debris. By unloading the discs mainly by cen.tri~ugal force, the need to use wiper blades to clear the discs is avoided and this simplifies and improves the effectiveness of the clean up operation.

Claims (14)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:-

1. Apparatus for recovering oil floating on a body of water comprising a vessel movable over the water through the floating oil, said vessel being equipped with oil catching means, an oil lifting mechanism mounted on the vessel and including a plurality of pickup discs arranged in sets each rotatable about a horizontal axis extending transversely of the mechanism, means for operating the oil lifting mechanism to move each set of pickup discs in turn between a loading position at least partly immersed in the water and a discharge position adjacent the oil catching means, and drive means for rotating each set of pickup discs at a first speed in the loading position whereby the discs are coated with oil and at a second speed in the discharge position whereby at least a portion of the oil adhering to the discs is thrown by centrifugal force into the oil catching means.

2. Apparatus as claimed in claim 1, in which each of said pickup discs is formed by a flexible oleophilic material.

3. Apparatus as claimed in claim 1, and in-cluding means for applying heat to the pickup discs in the discharge position whereby to reduce adhesion of the oil.

4. Apparatus as claimed in claim 1, 2 or 3, and including sweeping equipment mounted on the vessel ahead of the oil lifting mechanism operable to collect floating oil beneath the oil lifting mechanism as the vessel moves ahead.

5. Apparatus as claimed in claim 1 or claim 3, and including means for directing a cleaning fluid at the pickup discs in the discharge position.

6. Apparatus for recovering oil floating on a body of water comprising a vessel movable over the water and through the oil, a conveyor mounted on the vessel, said conveyor having an endless assembly providing an upper run and a lower run suspended into the water, oil catching means aboard the vessel alongside the upper run, said endless assembly including a plurality of rotatably mounted trans-verse shafts, a set of pickup discs mounted on each trans-verse shaft to rotate therewith, means for operating the conveyor to rotate the endless assembly and move the sets of pickup discs across the surface of the water and passed the oil catching means, and drive means for individually rota-ting the transverse shafts at a relatively slow speed when the pickup discs are in the water whereby to coat the discs with the floating oil and a speed sufficiently high when the pickup discs are near the oil catching means whereby some of the coating oil is thrown off the discs by centrifugal force.

7. Apparatus as claimed in claim 6, in which each of said pickup discs is formed of an annular band of a flexible oleophilic material.

8. Apparatus as claimed in claim 7, in which said lower run of the endless assembly is relatively slack and each transverse shaft is provided with float means whereby the sets of pickup discs are moved across the surface of the water with a portion of the discs projecting above the floating oil.

9. Apparatus as claimed in claims 6, 7 or 8, and including steam means for applying heat to the sets of discs in the vicinity of the oil catching means whereby to reduce adhesion of the coating oil.

10. Apparatus as claimed in claims 6, 7 or 8, and including sweeping equipment mounted on the vessel ahead of the conveyor, said sweeping equipment comprising a pair of arms diverging outwardly from the vessel, and sound pro-ducing devices mounted on the pair of arms and being oper-able to propel the floating oil collected between the pair of arms towards the path of travel of the vessel.

11. Apparatus as claimed in claims 6, 7 or 8, and including steam means for applying heat to the sets of discs in the vicinity of the oil catching means, said steam means including a plurality of nozzles circumferentially arranged around the transverse shafts near the sets of pickup discs whereby heated steam is directed at said discs to reduce adhesion of the coating oil.

12. A method of picking up oil floating on a body of water comprising the steps of moving the vessel across the body of water, driving a conveyor mounted on the vessel to dip oil pickup discs of the conveyor into the floating oil and then move the pickup discs inboard of the vessel, rotating the oil pickup discs at a relatively low speed when partially immersed in the floating oil to coat outer sur-faces of the pickup discs with some of the floating oil, and rotating the pickup discs when located inboard of the vessel at a sufficiently high speed to discharge most of the oil coating the discs into storage facilities aboard the vessel.

13. The method as claimed in claim 12, and including the additional step of applying heat to the pickup discs when located inboard of the vessel to reduce adhesion of the oil coating the discs.

14. The method as claimed in claim 13, and including the additional step of directing a cleaning fluid at the pickup discs to further reduce the amount of oil left clinging to the discs.