WO1994024374A1

WO1994024374A1 - Oil removing apparatus

Info

Publication number: WO1994024374A1
Application number: PCT/AU1994/000195
Authority: WO
Inventors: Peter Scott
Original assignee: Peter Scott
Priority date: 1993-04-16
Filing date: 1994-04-18
Publication date: 1994-10-27

Abstract

An apparatus for removal of oil floating on the surface of a body of water comprises a rotatable cylinder (1), a scraper blade (2) and an oil collection trough (3) for collecting oil removed from the cylinder (1) as it rotates. The apparatus is operated with a minor portion of the surface of the cylinder (1) submerged beneath the surface of the water and the speed of rotation of the cylinder (1) is selectively variable to optimise the rate of removal of the oil from the surface of the water.

Description

TITLE OIL REMOVING APPARATUS

This invention relates to an apparatus for removing oil from marine and fresh water oil spills as well as oil contaminated ground sites.

BACKGROUND ART Oil spills occur both on land and in the sea causing disastrous consequences for the immediate region in environmental and subsequent economic terms. The demand for oil is increasing with the increased industrialisation throughout the world, and with the increased demand the risk of further oil spills increases.

A number of methods have been devised to contain the oil, change or destroy the oil, or recover the oil from an oil spill. Methods for containing the oil include floating barriers which confine the spread of the oil and limit the break up of the spill into a number of smaller spills. Methods for changing or destroying oil from a spill include chemical and microbiological attack. Methods for recovering the oil from a spill have predominantly included the use of a roller or a drum to assist in the separation of oil from water in an oil-water mixture. These include apparatus disclosed in US Patent 4557832 and European patent specification EP246963. The apparatus disclosed in US patent 4557832 comprises a roller which has its upper surface at the level of the water surface, a scraper to remove the oil from the roller and a grate through which the removed oil passes into a receiving tray. The grate serves to prevent floating debris from entering the receiving tray and possibly blocking the pump. However highly viscous oil is also prevented by the grate from entering the receiving tray. The apparatus disclosed in European patent specification EP246963 is similar and comprises of a weir type roller positioned within a recovery compartment and a scraper which removes the oil so that the oil accumulates in the recovery compartment. The disadvantage of both above described apparatus is that the oil recovered still contains a substantial proportion of water which must be removed in a subsequent step or steps. Another problem is that floating debris, animal and plant life may interfere with the operation of the apparatus. Also the weir type roller apparatus cannot be operated in shallow water as the roller will contact the ground. Further there appears to be few if any apparatus adapted to remove oil from particulate matter such as sand from an oil contaminated beach front.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide an apparatus and method for recovering oil from oil-water mixtures and oil contaminated particulate matter and to overcome the abovementioned disadvantages of the prior art.

One aspect of the present invention resides in an apparatus for removing oil from an oil-water mixture, said apparatus comprising:- a rotatable cylinder having an outer surface adapted to bind oil thereto, said apparatus in use being rotatable about a transverse axis with a minor portion of said outer surface submerged in said mixture and major portion of said surface located above the level of said mixture; oil removal means for removal of oil from said outer surface; collection means to collect oil removed from said surface; and, drive means to rotate said cylinder at a predetermined rate. Also said rotatable member may be hollow or alternatively be solid suitably filled with material that assists in providing buoyancy. Said rotatable member suitably rotates about a horizontal axis. The speed with which said rotatable member rotates may vary but preferably at a speed which carries over the maximum amount of oil with the minimal amount of water. Preferably said rotatable member is a drum or a roller. The peripheral surface of said rotatable member may be formed from substances that are oleophilic. Alternatively the peripheral surface may be composed of hydrophobic or hydrophobic and oleophilic substances. Said peripheral surface is suitably composed of metal but may also be composed of wood, fabric or plastics. A preferable form of said peripheral surface is smooth steel. Further, said peripheral surface may be contoured to assist in the binding of oil thereto, or alternatively comprise of oil-absorbent material. Suitable forms of oil- absorbent material are metal wool, metal or plastics mesh fabric, matting and cellular plastics or rubber materials. Said peripheral surface may be heated to assist in binding of oil. The oil removal means may be positioned adjacent a rear portion of said rotatable member and may extend across its major surface. The oil removal means may extend horizontally or obliquely. The oil removal means may contact said surface to remove oil therefrom and if required the oil removal means may maintain contact to said portable member by a tension means. The tension means is preferably a tension spring.

The oil removal means may suitably be a scraper. Alternatively said removal means may be another rotatable member, which is preferably a drum or roller. The further rotatable member may be in contact with a scraper. The collecting means may extend below said oil removal means. The collecting means is preferably a container and may include an oil discharge outlet.

Suitably, said collecting means includes a pump to pump the oil out of said collecting means.

The drive means may be dependent or independent. A suitable dependent the drive means may be in the form of a paddlewheel which rotates the rotatable cylinder with relative movement of the water from which the oil is being removed.

The apparatus may also include a side wall scraper for removing oil from the side wall of the rotatable cylinder. The scraper may extend horizontally or obliquely and is suitably located adjacent said removal means. The oil removed by the side wall scraper may be collected in said collecting means.

Two or more of said apparatus may be linked in parallel or in series. In another aspect the invention resides in a system for removing oil from a large body of water contaminated with oil, comprising said apparatus described above, and a buoyant support means to support said apparatus in a large body of water. The buoyant support means may be tethered or movable in the body of water. The buoyant support means may be fixed by a permanent or temporary anchorage. The permanently fixed anchorage may comprise an attachment to pylons whereas the temporarily fixed anchorage may comprise an attachment to moorings or anchors. The buoyant support means may comprise float chambers, pontoons, a barge or other marine vessel. A mobile support means may suitably be self-propelled, or attached to a craft that is propelled.

If required a plurality of buoyant oil removal apparatuses according to the invention may be connected side by side to function as an oil removal barrier or boom. Suitably respective rotatable cylinders are interconnected by drive shafts having flexible joints or couplings. The support means is suitably attached to the buoyant support means to permit selective submergence of the rotatable cylinder to different levels.

A further aspect of this present invention resides in a system for removing oil from oil- contaminated particulate matter such as sand, or earth and comprises the combination of an oil removal apparatus described above, and a separating tank which in use is adapted to contain water and separates oil from particulate matter to form an oil-water mixture, oil from which may be removed by said apparatus.

The separating tank may contain one or more agitation means which can located adjacent to the inside base of said tank to facilitate the removal of oil from particulate matter. The agitation means is suitably air and/or water jets preferably located adjacent each other. Preferably the degree of agitation from the individual agitation means decreases with distance from the site of entry of the oil-contaminated particulate matter. The separating tank may contain a plurality of baffles which also assist in the separation of oil from particulate matter. The baffles may be vertically disposed and preferably do not extend to the base of said tank. The baffles suitably extend near to the surface of the oil-water mixture.

The separating tank may contain one or more oil removing apparatus. The plurality of said apparatus is suitably located adjacent to the surface of the oil-water mixture and distal from the site of entry of the oil-contaminated particulate matter. The plurality of said apparatus is preferably located adjacent to the baffles such that the immediate oil- water mixture is minimally disrupted by the agitation.

Oil-contaminated particulate matter may enter the said tank as part of a larger continuous process. Oil-contaminated particulate matter may be introduced in a number of ways, suitably by conveyor belt, elevators or via pipes. Preferably the oil contaminated particulate matter enters adjacent one end of the said separating tank and distal from said apparatus. Decontaminated particulate matter may be removed from adjacent to the opposite end to the site of entry of the oil-contaminated particulate matter. Decontaminated particulate matter may be removed by collection from or near the base of said tank and transferring it to outside said tank. Preferably decontaminated particulate matter may be removed by a bucket elevator.

Water for said separating tank may be added by the preferred water jets. Alternatively water may be added separately. Further the level of the oil-water mixture in said separating tank may be regulated so that no more water is added when the level of the oil- water mixture reaches a predetermined height. The regulation of the addition of water is suitably performed by sensors in said apparatus and/or said separating tank.

Other chemicals may also be added to the said separating tank to facilitate the separation of oil from the oil-contaminated particulate matter. These chemicals may be added with the water, either accompanying the addition of water or pre-conditioning the water. Alternatively the chemicals may be added independent of the addition of water. Suitable chemicals which can be added to the oil-water mixture include detergents and solvents.

Said separating tank may be in a stationary position when in use. The stationary position may be of a temporary or permanent establishment. Alternatively said separating tank may be mobile when in use. Said separating tank may be supported in a truck or be towed in conjunction with a machine such as a grader which accumulates oil-contaminated particulate matter.

In order that the invention may be more fully understood and put into practical effect, preferred embodiments of the present invention will now be described by way of example with reference to the drawings .

BRIEF DESCRIPTION OF DRAWINGS Figure 1 is a schematic perspective view of an apparatus for removing oil from a large body of water contaminated with oil.

Figure 2 is a cross sectional view of a system for removing oil from oil-contaminated particulate matter .

DETAILED DESCRIPTION Figure 1 discloses an apparatus for removing oil from an oil-water mixture comprising a rotatable member in the form of a cylindrical roller 1 , an oil removal means in the form of a scraper 2, a collecting means in the form of a container 3, and a support means in the form of side plates 6 attached to a buoyancy chamber or the like (not shown) . The roller 1 has a peripheral surface 7 made of steel. The scraper 2 is located on the rear portion of the major surface of roller 1 and extends horizontally thereacross. Scraper 2 is biased against roller 1 by a tension spring. A side wall scraper 10 is located on the side wall of roller 1 below the scraper 2. The side wall scraper 10 extends horizontally across the wall such that oil removed therefrom flows into the collecting tray 3. The side wall scraper 10 is similarly a biased by a tension spring. The collecting container 3 is shaped such that oil moves towards outlet 4. Roller 1 is supported for rotation by axle 8, journalled in bearings 5, and is connected to a drive means (not shown). Plates 6 support the roller axle 8 and may be attached to further support means such as a buoyant pontoon or the like.

In use the apparatus is positioned in the oil- water mixture so that oil from the mixture binds to the surface of the rotating roller 1 and passes clockwise towards the scraper 2 where oil is removed by the contacting scraper and falls into the collecting container 3. From the collecting container 3 the oil passes out through the container outlet. The roller is rotated by a drive means at a speed where the maximum amount of oil is found with the minimal amount of water included. Experiments have shown that the rate of recovery of oil from the surface of a body of water is optimised by selective adjustment of the rate of rotation of roller 1 , the rate of rotation being dependent upon:-

1. The viscosity of the oil.

2. The diameter of the roller.

3. The surface characteristics of the roller. Surprisingly, experiments have shown that a smooth plain steel and roller surface is most effective for most oil types.

By way of example, a 300 mm diameter roller has an optimum revolution rate of 10-15 rpm for a heavy crude oil whereas this can be reduced to about 4-5 rpm for a lighter crude oil or lubricating oil.

An apparatus having a roller diameter of about 2m and a length of 4m, operating at 10 to 15 rpm when floating in water having a 50 mm thick layer of crude oil floating thereon will recover about 100,000 litres per hour of spilt oil.

Figure 2 shows a second embodiment of the invention wherein oil may be separated from oil- contaminated particulate matter. This apparatus comprises a separating tank 21 , rotatable members in the form of rollers 22, oil removal means in the form of scrapers 23, and a collecting means in the form of containers 24.

The rollers rotate about axles 25 which are connected to a respective drive means or a common drive train. The separating tank contains baffles 26 which are spaced within the tank. These baffles do not extend to the bottom of the tank nor to the surface of the oil-water mixture. Between each baffle there are air jets 27 and water jets 28 each connected to a respective source of pressurised air 27a and pressurised water 28a. Decontaminated particulate matter is removed by the bucket elevator 29.

In use, oil-contaminated sand for example is introduced into the separating tank by the conveyor belt 31. In the separating tank the oil is separated from the sand particles by agitation caused by the water and air jets. The agitation forces the sand towards the bucket elevator 29. The baffles 26 demark zones in the separating tank and thus assist in the settling of the sand. Decontaminated sand is removed by the bucket elevator 29 and inclined portion 30 assists in the deposition of decontaminated sand adjacent the bucket elevator 29.

One or more oil removing apparatus operate within the separating tank but these are located after the first baffle to maximise separation and allow the particulate matter to settle. The oil removing apparatus is positioned so that each roller is immediately adjacent to a respective baffle. Oil is removed from the resulting oil-water mixture by the binding of the oil on the surface of the roller and its subsequent removal by the scraper. Oil is collected in the collecting tray and eventually passed through the container outlet 32.

It should be appreciated that various other changes and modifications may be made to the embodiments without departing from the spirit and scope of the invention.

Claims

1. An apparatus for removing oil from an oil-water mixture, said apparatus comprising:- a rotatable cylinder having an outer surface adapted to bind oil thereto, said apparatus in use being rotatable about a transverse axis with a minor portion of said outer surface submerged in said mixture and major portion of said surface located above the level of said mixture; oil removal means for removal of oil from said outer surface; collection means to collect oil removed from said surface; and, drive means to rotate said cylinder at a predetermined rate.

2. An apparatus as claimed in claim 1 wherein said rotatable cylinder comprises a buoyant member.

3. An apparatus as claimed in claim 1 or claim 2 wherein the outer surface of said cylinder is contoured.

4. An apparatus as claimed in claim 3 wherein said outer surface is covered with a mesh fabric.

5. An apparatus as claimed in claim 1 or claim 2 wherein the outer surface of said cylinder is a smooth metallic surface.

6. An apparatus as claimed in any preceding claim wherein the oil removal means comprises a scraper.

7. An apparatus as claimed in any preceding claim wherein said oil collection means comprises a container located below said oil removal means.

8. A system for removal of oil from the surface of a body of water, said system comprising an apparatus according to any one of claims 1-7 whenever mounted on a buoyant support structure.

9. An apparatus for removal of oil from oil contaminated particulate matter said apparatus comprising:- a separation vessel having a plurality of spaced baffles therein, said baffles extending transversely of said vessel to define a plurality of separating chambers, respective upper edges of said baffles, in use being located below a level of water in said chamber said respective lower edges of said baffles being located above a floor of said vessel; conveyor means adjacent one end of said vessel for removal of particulate matter therefrom; agitation means associated with one or more of said separating chambers; and, one or more oil collecting devices as claimed in any one of claims 1-7, said one or more oil collecting devices in use being positioned adjacent a liquid level in said vessel with a minor portion of an outer surface of a respective rotatable cylinder being submerged below said liquid level, respective rotatable cylinder of each of said one or more oil collecting devices being located adjacent an upper edge of a respective baffle.

10. An apparatus as claimed in claim 9 wherein said agitation means comprises one or more nozzles for directing a source of pressurised air and/or water into a separating chamber to agitate a body of liquid therein.

11. An apparatus as claimed in claim 9 or claim 10 wherein said separation vessel is mobile for transportation across a land surface.

12. An apparatus as claimed in claim 11 wherein said apparatus is self propelled.

13. A method for collection of oil floating on the surface of a body of water comprising the steps of:- contacting the oil with a rotating cylinder of an apparatus of any one of claims 1-7; removing oil accumulated on the surface of the cylinder by a scraper blade; and, collecting oil so removed in a collection means.

14. A method of separating oil from particulate matter contaminated with oil, said method comprising the steps of:- depositing a quantity of oil contaminated particulate matter into a body of water in a separating chamber at one end of an apparatus according to any one of claims 9-12; agitating the water in each of a plurality of separating chambers; and, collecting from the surface of the body of water adjacent a respective baffle, oil floating on the surface of the water by a rotatable cylinder of an apparatus according to any one of claims 1-7.

15. A method as claimed in claim 14 wherein particulate matter, from which oil has been separated, is removed from said vessel by a conveyor means at an end remote from said one end.