TECHNICAL FIELD OF THE INVENTION

The present invention relates to a system for the collection and the disposal of substances that may be harmful to the environment, as for instance petroleum products, particularly crude oil, on polluted water whilst ensuring both clean water and clean air, wherein the oil is mechanically collected by a collecting device including a rotatable collector which separates the oil from the water, and combustion of the collected products in a partly closed incinerator with a primary combustion process and a secondary combustion process, by which means a generation of harmful substances as for instance dioxines and similar are avoided.

BACKGROUNP TO THE INVENTION

Modern society has become more and more dependent on substances which may constitute severe environment hazards, as for instance petroleum products, particularly crude oil. Because of the wide-spread use of these substances there is a very high risk that the substances in question accidentally are released into the environment. Petroleum products and crude oil are particularly problematic when they are released into seas, lakes or other water courses, and this unfortunately nowadays is a very common occurence. Oil released into water will have a harmful effect on the environment for at least several decades cf. for instance the "Amoco Cadiz" catastrophe in the English Channel. As can be seen from this catastrophe, it is extremely difficult to collect the released oil in such a way that the water effectively is purifed from oil. In spite of the large efforts made at the time to collect and contain the oil, severe harmful effects still can be observed in the affected areas. In this context there also is a difficult problem regarding how the oil, which has been collected is to be disposed of. Such a disposal of course preferably should take place in connection with the collecting of the oil, and which until now mostly has been done by simply burning the oil on the beach. However, as a result however the atmosphere in the affected area also will be polluted.

Thus there is a great need for a system which efficiently collects oil accidentally released into water which also assures that the oil can be disposed of without polluting the atmosphere.

BRIEF DESCRIPTION OF THE INVENTED CONCEPT

The present invention aims to solve the above and other problems and this is done by providing a device which includes at least one rotatable curved envelope whose generatrixes are mutually parallel, and which has two free edges, at least the inner, free edge being parallel to the generatrixes, this latter edge being arranged adjacent to a removal device, preferably in the form of a rotatable screw, in such a way, that the envelope at least partly surrounds the removal device with the second, outer, free edge of the envelope further being located at distance from the removal device, the envelope also being rotatable around the center of the removal device, in such a way that the inner free edge of the envelope substantially follows the periphery of the removal device when the envelope is rotated, by which means the oil is collected and transferred to the incinerator which is designed as a trough provided with a lid, the combustion taking place in the lower part of the incinerator where primary air is supplied, a secondary combustion further taking place in the upper part of the incinerator by means of a carefully regulated supply of secondary combustion air, the primary air being supplied to the bottom of the trough, i.e. the primary combustion chamber, and being uniformly distributed through its surface, the secondary combustion air being supplied to the secondary combustion chamber by means of channels in the lid opening into air outlets being directed at an angle towards the primary combustion bed, the lid further comprising a main part being substantially parallel to the bottom of the trough and two longitudinal side pieces arranged at an angle to, and sloping downwards from the main part, one of said side pieces being attached to one of the upper edges of the trough and the second side piece defining a longitudinal opening together with a second upper edge of the trough, the lid further being open at at least one end.

BRIEF DESCRIPTION OF THE ATTACHED DRAWINGS

Fig 1 illustrates the main components of the system.

Fig 2 is a cross section of one of the main component of the systems, namely the oil collecting device.

Fig 3 is a cross section of the second main component of the system.

Figures 4 - 6 illustrate three different embodiments of the envelope-shaped oil collecting part of the oil collecting device.

Fig 7 finally illustrates how the system can be arranged in a oil collecting vessel which in this case is in the form of a catamaran.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS OF THE INVENTION

As stated above, figure 1 illustrates the main components of the system. Thus the oil collecting device is designated 1 and comprises a rotatable curved envelope 2 which in this particular case is in the shape of an helix, although it of course can have any other suitable shape, for instance a half circular cross-section. The generatrixis of the curved envelope are mutually parallel. The curved envelope 2 further has two free edges 20, 21. The inner free edge 20 is parallel to the generatrixis and is arranged adjacent to a removal device 3 in the form of a rotatable screw. The envelope 2 partly surrounds the rotatable screw 3 and its outer free edge 21 is located at distance from the rotating screw 3. The envelope 2 is further rotatable around an axis coinciding with the rotational axis of the rotatable screw 3, in such a way, that the inner free edge 20 follows the periphery of the rotating screw 3 when the envelope 2 is rotated. The ends of the curved envelope further are provided with an end piece 24, 25 each who are oriented perpendicularly to the generatrixes of the envelope 2. The envelope 2 further is perforated, or may be in the shape of a net. The inner surface of the curved envelope 2 is provided with a plurality of flanges 4 which are oriented somewhat obliquely in the relation to a plane being perpendicular to the axis of rotation of the rotatable screw 3. The flanges 4 and the end pieces 24, 25 may or may not be perforated. In use the system further comprises an incinerator 6 which is connected to the oil collector by means of a conduit 5. This incinerator is in the form of a trough 7 having a lid 8. The combustion mainly takes place in the lower part of the incinerator 6 where primary air is supplied. A secondary combustion further takes place in the upper part of the incinerator 6 by means of a carefully regulated supply of secondary combustion air. In this particular embodiment, the primary air 15 is supplied to the bottom of the trough 7, i.e. the primary combustion chamber 14, and is uniformly distributed through the surface of the bottom. The secondary combustion air is supplied to the secondary combustion chamber 22 by means of channels 18 in the lid ending in air outlets 19 which are directed at angle towards the primary combustion bed formed in the bottom of the trough 7. The lid 8 comprises a main piece 9 which is parallel to the bottom of the

trough 7 and connected to two side pieces 10, 11. These side pieces are arranged at an angle to the main piece 9 and sloping downwards -outwards therefrom. The interior angle 1/ formed between the main piece 9 and the side piece 10 is 115°, whilst the interior angle 0 formed between the main piece 9 and the side piece 11 is 110°. The side piece 10 is attached to the trough 7 whilst the side piece 11 further is connected to a second side piece 12 which is oriented downwards - inwards into the interior of the trough. The interior angle /3 formed between the side piece 11 and the side piece 12 is 115°. The free edge of the side piece 12 is located at a distance from the upper edge of the trough 7, thus defining a longitudinal opening 13. Nozzles 19 for the secondary combustion air is formed along the free edge of the second side piece 12. Fig. 2 shows how the oil collecting device is oriented and functions in operation. The device and the water move relative to each other in the direction of the arrow 26, whilst the curved envelope 2 is rotated in the direction of the arrow 27, which means that the free edge 21 always passes through the oil from beneath the surface of the water, thus enclosing a portion of oil between its inner surface and the transport screw 3 and forcing the oil towards the transport screw 3. The oil is then transported to the conduit 5 by means of the rotatable transport screw 3 and forced through this conduit into the incinerator. This procedure may be facilitated by means of a pump. The removing action of the transport screw 3 may be supported by means of the obliquely oriented flanges 4 which aid in directing the oil towards the side of the oil collector where the collected oil is removed. The oil is collected in the trough 7 of the incinerator 1 which preferably is provided with an automatic ignition device (not illustrated). A primary combustion will take place in the primary combustion chamber 14 formed in the lower part of the trough 7. This combustion however would normally create large amounts of smoke, -soot and/or a plurality of harmful adjents such as dioxine etc. To avoid this, secondary combustion air is supplied through the lid 8, as described above, and which ensures that a secondary combustion will take place in the space 22, i.e. the secondary combustion chamber, which is defined beneath the lid 8. Because of the specific angles and orientations of the nozzles 19 and the side pieces 10, 11, 12 and the main piece 9 of the lid, an exactly regulated, turbulent, secondary combustion will take place beneath the lid. The direction of the injected secondary air is such that any premature exit of fumes etc. through the opening 13 will be prevented, which does ensure that the secondary combustion is complete. It

should be pointed out here that the ends of the lid are open and that the combustion gases will not pass through these open ends before they have been subjected to a complete combustion process wherein all substances that may be harmful to the environment have been destroyed.

Fig. 7 illustrates how the system is installed in a catamaran-type oil-collecting vessel. The oil-collecting device 1 is installed in the space between the two hulls 29, 30 perpendiculary to the direction of movement of the vessel. The oil will be forced inwards between the two hulls 29, 30 and compressed to a certain extent, since the distance between the two hulls decreases due to the widening of the two hulls seen from the stems of the ship. The incinerator is arranged in one of the two hulls, and the oil, which is collected, is fed directly into the incinerator by means of the rotatable screw 3. In this way a complete, self-contained unit is achieved which at the same time collects oil from polluted water and disposes of the oil.

Figs. 4-6 illustrate some preferred embodiments of the cross- section of the curved envelope. As mentioned above the curved envelope may be in the form of an helix. Surprisingly it appears that three kinds of helixes are particularly suitable for this purpose, namely the archimedean helix, the logarithmic helix, and the hyperbolean helix.

As can be seen in Fig. 4 the archimedean helix in question is defined by the equation

wherein r and are polar coordinates and r ₀ is constant. r ₀ is chosen in dependence of the actual size of the curved envelope and may for instance be 2 m. P varies in a range which corresponds to +90°— +450°.

The logarithmic helix in question shown in Fig. 5 is defined by the equation

r = a &

wherein r and ψ are polar coordinates, m = cot <X and a and of are constants, a is chosen in dependence of the actual size of the curved envelope, and may for instance be about 1,5 metre, <* , which is the angle of

the tangent of the helix with r, or the radius vector, is chosen to be between 75° and 105°, and <p should preferably vary in a range corresponding to +450- -270°.

The hyperbolean helix in question shown in Fig. 6 finally is defined by the equation

r φ a

r and ψ again being polar coordinates, a being a constant whos value depends on the actual size of the curved envelope and in this case is the length of an arc, and ψ preferably should vary in a range corresponding to 0— 360°. These three preferred embodiments of the helical shape of the curved envelope have proved to form an angle of attack with the surface of the water, and thus with the oil located thereon, which is particularly successful in collecting the oil on the water.

The device as described above functions perfectly when the polluting substances have the general characteristics of crude oil and similar. However, should the polluting substances be less viscuous and for instance have a viscosity approaching that of water and thus escape together with the water out from the collecting device, the system is complemented with a supply device which is located in front of the rotatable, curved envelope, seen in the direction of movement. This supply device can, if necessary, distribute thickening agents over the polluted water, by which means the polluting substances may be given a consistency which is compatible with the properties of the oil-collecting device. The supply device further can be used to distribute absorbing substances, such as bark and similar, and of course also to distibute agents that in a manner known per se causes sunken oil to raise to the surface where it can be collected by the collecting device. The supply device can for instance comprise a tube provided with nozzles if the agent to be distributed is in liquid or pulverulent form. In the latter case the supply device may of course also be in the form of an endless band, equipped with metering device.

The invention of course can be modified in many ways within the scope of the appended claims. Although the system has been illustrated as being arranged in a vessel, the collecting device of course could be fixedly arranged in for instance a drainage ditch or similar, or even across a water

course, collecting any oil or other harmful agents which may float downstream on the water course, and which immediately is disposed in the incinerator. As mentioned above, the incinerator can have an automatic ignition device, which immediately will ignite any oil coming into the incinerator, and this is particularly advantageous when the system is used stationary since it automatically will dispose of any polluting agents in the water course without any need for a scheduled supervision. An oil sensing device may also be arranged in front of the oil collecting device, starting and stopping the device according to if oil is sensed or not. In some cases it may prove advantageous to design the curved envelope without any perforations or holes and instead arrange the holes and perforations in the flanges and in the end pieces. If both the curved envelope arid its end pieces are designed with perforations, it may in some cases be advantageous to design the flanges without any holes or perforations. This would for instance depend on the type of polluting agents that are expected to be encountered. The end pieces of the envelope have been illustrated as being attached to the envelope. However it is equally possible to design the end pieces stationary and for instance fixedly attached to the frame of the rotatable transport screw. In this case the end pieces preferably should be without any holes or perforations.

Furthermore, the nozzles 19 in the side piece 12 of the lid may be designed as one single longitudinal slit extending along the entire length of the edge of the side piece.