GB2038651A

GB2038651A - The dispersion of oil floating on water

Info

Publication number: GB2038651A
Application number: GB7941015A
Authority: GB
Original assignee: Individual
Current assignee: Individual
Priority date: 1978-11-28
Filing date: 1979-11-28
Publication date: 1980-07-30

Abstract

Ultrasonic vibrations are generated at the water/oil interface to cause cavitation and emulsification at said surface. In a preferred embodiment a gas, with an oil solvent, in mist or vapour form, is released to flow through the interface, to assist cavitation and agitation. In apparatus for carrying out the dispersion, a plurality of spaced apart vibrations 4 are carried by a floating structure provided with gas supply ducts 7. <IMAGE>

Description

SPECIFICATION Improvements in or relating to the dispersion of oil This invention is concerned with the dispersion of oil, particularly crude oil, floating on water.

The occurrence of oil slicks on water at sea and in rivers is a present day hazard and the removal of such slicks is a matter of great difficulty, requiring the use of large quantities of chemical dispersants or of mechanical means for confining and removal of the bulk of the oil.

The present invention seeks to provide a novel method of, and apparatus for, dispersing oil floating on water.

According to the present invention there is provided a method for dispersing oil floating on water comprising the steps of generating ultrasonic vibrations at a number of locations at the interface of water and oil to create cavitation and emulsification at said interface.

Preferably the method includes the step of generating said ultrasonic vibrations via vibrators in spaced apart relationship and which extend from the oil through the interface to the water therebeneath.

Preferably the ultrasonic vibration generating means is supported on a floating structure and said structure is displaced in a direction generally parallel to said interface. With such an embodiment the power source for said ultrasonic generating means is conveniently mounted on said floating structure.

Preferably the method includes the step of introducing a gas, such as air or an inert gas, into said interface to assist in creating cavitation and emulsification at the interface. With such a method it is convenient to introduce an oil solvent, in mist or vapour form, into said gas before releasing said gas at said interface.

In a preferred embodiment in accordance with the invention the method includes the step of introducing said gas into said interface adjacent each ultrasonic vibration generating means.

The invention also envisages apparatus for dispersing oil floating on water and comprising a plurality of vibrators in spaced apart relationship and intended to pass through the interface of oil and water, and means for vibrating said vibrators at ultrasonic frequencies.

Preferably the vibrators are of elongate form, intended to operate with their axes at right angles to the plane of the interface.

In one embodiment in accordance with the invention the vibrators comprise piezoelectric transducers whilst in an alternative, and more preferred, embodimentthe vibrators comprise magneto-strictive transducers.

In a preferred embodiment in accordance with the invention the apparatus includes ducts for introducing a gas into said interface and, conveniently, the apparatus includes means for introducing an oil solvent in mistorvapourform into said gas before releasing the gas from said ducts.

Preferably the apparatus is used in combination with a floating structure, said structure supporting the vibrators in the desired spaced relationship and at the desired depth. With such a construction the floating structure conveniently supports generating means for supplying power to said vibrators.

It will now be seen that the present invention proposes the dispersion of oil by generating ultrasonic frequencies at the interface between the oil and the water, thus agitating the oil and water at the interface and thereby effecting emulsification at said interface. When the water is moving so as to flow with the oil past static locations the ultrasonic vibration generating means, for example the vibrators, may be supported by the static locations in spaced relationship at right angles to the direction of flow. When the oil has substantial thickness, greater than that which can be dispersed by a single row of vibrators the vibrators may be arranged in banks spaced apart in the direction of flow.

When the water and oil are not flowing past static locations, a condition frequently met in open seaways, the ultrasonic vibration generating means is preferably supported by a floating structure, such as a boat, raft, floating boom, hovercraft, or helicopter and, once again, when the oil has substantial thickness, the floating structure may present the vibration generating means in spaced apart rows.

The power means for the ultrasonic vibration generating means may, if the floating structure has ample stability, be mounted on the floating structure but in an alternative embodiment the power source may derive from a single power source adapted to supply power to a plurality of floating structures.

It will be appreciated that the greater the number of vibrators the greater will be the effect so that each floating structure preferably carries as many vibrators as is possible having regard to their convenient spacing apart for maximum efficiency and the electric power available.

In one preferred embodiment in accordance with the invention it is visualized that one vessel, such as a tug, carrying an electrical generator will tow a number of vibrator-carrying floating structures, the tug will supply electrical energy to the vibration generating means on each of the floating structures and the floating structures will preferably be relatively lightweight structures and thus capable of being carried on board a support vessel when not in use or during transport to the places of use.

As stated the vibrators are conveniently transducers, possibly piezoelectric, for example in the range of 20-100 KHz (1-10 HP) each, largely dependent on the capacity and nature of the floating structure and the number of transducers which can be effectively worked by a given electrical supply will be readily determined by a person versed in the art.

The invention will now be described further by way of example with reference to the accompanying drawings in which:~ Fig. 1 shows, diagrammatically, a side view of a floating structure with apparatus for generating ultrasonic vibrations and Fig. 2 shows diagrammatically, but on an enlarged scale, one arrangement for the electrodes for the Fig.

1 embodiment.

In Fig. 1 a floating structure 1, preferably shaped at its forward end at 1' to facilitate its passage through liquid and whereat it is provided with means (not shown) for the attachment of a towing cable if the floating structure is not provided with a power driven propulsion means. The floating structure 1 is shown as floating on a slick of oil 2 on a body of water 3, such as the open sea.

The floating structure 1 carries a plurality of elongated electrical power operated ultrasonic vibrators 4, of which only four are illustrated, arranged to receive operating electric current from a generator 5 carried on the floating structure 1, or by cable, as from a towing vessel or from a land based generator.

Thefloating structure 1 will present as many electrodes 4 as the power source 5, or the power supplied by an external cable, can effectively operate, the electrodes are preferably distributed in spaced apart relationship in rows, each row being transverse to the intended direction of travel for the floating structure 1 through the water, and the rows being spaced apart in the longitudinal direction of the floating structure.

The electrodes 4 pass through the interface between the oil 2 and water 3, conveniently at right angles to said interface, and the vibrating means for the electrodes 4, generally indicated by reference numeral 6 in Fig. 2 are conveniently located above the free surface of the oil 2.

The vibrators are conveniently piezoelectric transducers but, alternatively, comprise magneto-strictive transducers.

To assist cavitation in the region of the interface the vessel may present gas release means indicated in Fig. 2 by ducts 7 which extend through the oil to the watertherebeneath and are supplied with a pressure gas, conveniently air or an inert gas such as nitrogen, from a supply (not shown) on the floating structure 1. The gas released from ducts 7 form bubbles which pass upwardly from the water through the interface to the oil and thus enforce cavitation at the interface.

When very rapid dispersion of the oil is required the gas supplied to ducts 7 may be loaded with an oil solvent, the solvent being preferably present in the gas as a mist or in a vapour phase, conveniently to pass into solution with the oil as close to the interface as is possible.

In operation the floating structure 1, or a plurality of floating structures 1 in side by side relationship, are displaced, by on board power sources or by a towing vessel, in a direction parallel to the interface between oil 2 and water 3, and with power supplied to the vibrator mechanisms 6 the electrodes 4 are vibrated at ultrasonic frequencies and thus cause agitation, with cavitation and emulsification, at the interface.

As will be apparent the floating structure, or structures, 1 will be displaced over the oil slick to be dispersed, if the oil slick covers a substantial area grea ter than the path swept by the floating structure or structures, a number of passes may be necessary to disperse the oil slick and, if the oil slick has substantial depth so that it cannot be wholly dispersed by a single passage of the floating structure, a number of passages may be necessary.

Whilst the term "emulsification" has been used herein there may not in fact be a true emulsification of the oil and water but there will be a breaking up of the oil mass into small globules, which will disperse due to the movement of the water natural in the case of sea and rivers and artificially created in the case of harbours, and the term "emulsification" in this specification is intended to cover such small globule formation and dispersion.

Claims

1. A method for dispersing oil floating on water comprising the steps of generating ultrasonic vibrations at the interface of water and oil to create cavitation and emulsification and said interface.

2. A method as claimed in claim 1 including the step of generating said ultrasonic vibrations via vibrators, in spaced apart relationship and which extend from the oil through the interface to the water therebeneath.

3. A method as claimed in claim 1 or 2 including the step of supporting the ultrasonic generating means on a floating structure and displacing said structure in a direction generally parallel to said interface.

4. A method as claimed in claim 3 including the step of providing a power source for said ultrasonic generating means on said floating structure.

5. A method as claimed in any preceding claim including the step of introducing a gas into said interface.

6. A method as claimed in claim 5 including the step of introducing an oil solvent, in mist or vapour form into said gas before releasing said gas towards said interface.

7. A method as claimed in claim 5 or 6 including the step of introducing said gas into said interface adjacent each ultrasonic vibration generating means.

8. Apparatus for dispersing oil floating on water comprising a plurality of vibrators in spaced apart relationship and intended to pass through the interface of oil and water, and means for vibrating said vibrators at ultrasonic frequencies.

9. Apparatus as claimed in claim 8 in which the vibrators are of elongated form intended to operate with their axes at right angles to the plane of the interface.

10. Apparatus as claimed in claim 8 or 9 in which the vibrators comprise piezoelectrictransducers.

11. Apparatus as claimed in claim 8 or 9 in which the vibrators comprise magneto-strictive transducers.

12. Apparatus as claimed in claim 8, 9, 10 or 11 including ducts for introducing a gas into said interface.

13. Apparatus as claimed in claim 12 including means for introducing an oil solvent in mist or vapour form into said gas.

14. Apparatus as claimed in any preceding claim in combination with a floating structure, said structure supporting the vibrators in desired spaced apart relationship and depth.

15. Apparatus as claimed in claim 14 in which said floating structure supports generating means for supplying power to said vibrators.

16. Apparatus, substantially as hereinbefore described, with reference to and as illustrated in the accompanying drawings.