A METHOD AND APPARATUS FOR REMOVING OILY MATERIALS AND FLOATING MATTERS IN GENERAL FROM THE SURFACE OF BODIES OF WATER

Abstract: A method is described for collecting, from the water, oily matters and wastes in general, floating on the surface thereof, which comprises separating, from the lower layers, a surface waste containing layer, subjecting the same to subsequent concentration operations of said wastes and ejection of the underlying water. An apparatus for practising such method comprises a floating structure having good seaworthiness qualities, adapted to be disassembled in a number of parts, provided with means for separating a thin surface layer bearing the whole amount of wastes, and for introducing them in a large movable decantation basin (B) adapted to follow the major wave motion, with decanted water ejecting means (F, G), with means for transferring liquid bearing already concentrated oily matters to a system of tanks (U) communicating with each other for further decantation and final separation of oil from the water, and with means adapted to hinder the internal wave motions (9, 10). The apparatus does neither require continuous personnel attendance on board nor interruption of operations during unloading of the collected oily wastes.

Description: A METHOD AND APPARATUS FOR REMOVING OILY MATERIALS AND FLOATING MATTERS IN GENERAL FROM THE SURFACE OF BODIES OF WATER This invention concerns a method for removing oily materials, and floating matters in general, from the surface of bodies of water, as well as an apparatus whereby said method can be put into practical use. A Large number of methods and apparatus are known for removing oily and floating waste (which in the following disclosure will be simply designated in general as "oil") from the surface of bodies of water, and in particular from the surface of the sea, of lakes and rivers. For exemplary purposes, reference is made to the method and apparatus described in British Patent 1 206 794. However, said methods and apparatus already known in the art, have considerable drawbacks, and particularly the following: a) a very low collecting efficiency, further remarkably reduced if an even slight wave motion is present; b) remarkable transportation problems due to the large size of the apparatus, when they have to work in an even slightly rough sea, and the fact that they cannot be easily disassembled in order to make their transportat¬ ion easier; c) a high operation complexity which makes absolutely compulsory a continuous attendance on board of personnel whose safety often puts a constraint to the use of such apparatus, which are further burdened by the logistics of said personnel; d) oil collection can be performed only either when the apparatus is moving forward through the bodies of water to be purified, or only when the apparatus Is at a standstill, in that both possibilities are not provided in the same apparatus; e) low operational flexibility, whereby said apparatus seldom perform i optimum operating conditions; f) unsatisfactory seaworthiness as far as manoeuvring and wave motion resistance, especially at sea. It is an object of the present invention to provide a method and an apparatus /for removing oxly ana in general floating waste matter from bodies of water, which overcome the above mention¬ ed drawbacks known In the art. One of the basic features of this invention is the fact that oily matter removal may be performed with a constantly high separating efficiency, even in rough sea conditions, and by means of an apparatus whose weight and dimensions are relatively limited, at least compared to similar apparatus already known in the art. That is possible owing to the fact that, on the one hand the collection of the whole amount of oil involved is guaranteed, and on the other hand the amount of water collected with the oil is a minimum. Furthermore, the oil floating on the surface of the body of water, before being sent to the final decantation phase, is concentrated and simultaneously separated from the high¬ est possible quantity of water formerly associated therewith. A further important aspect of this invention, which improves the oil removal efficiency, is the fact that the various phases of collecting, concentrating and decanting said oil are performed in order to reduce to a minimum the possibility of turbulence arising in the liquid body, and that for instance by providing mechanical means for setting in motion the various liquid flows only downstream of their final separation, and means adapted to reduce the effect of the turbulence induced by the wave motion on the liquid flows being treated, in addition to special design features and devices. A further feature of this invention is the possibility to be readily disassembled in order to make it easily transportable along roads, and then assembled again near the usage location. Still according to this invention, the process is such that it can be followed through automatic and/or radio-controls to the operating components of the apparatus wherein it is performed, whereby continuous attendance of personnel on bord may not be required. In this way it has been made possible, on the one hand to provide the apparatus with qualities of further reduced weight, and on the other hand to enable the apparatus to be used also in very rough sea conditions, when the apparatus already known would not be able to operate for personnel safety reasons. A further feature of this invention is the fact that the oil transfer operation to the stocking facilities can be performed simultaneously to the forward motion of the apparatus, or while the latter is at a standstill, without having to interrupt the collecting operations. A further particular advantage of this invention relati¬ ve to the state of the art resides in the possibility to adjust the plurality of operating parameters to the variable conditions associated with each particular pollution reducing operation, such as the roughness of the sea, the density and thickness of the oil layer, the removal velocity, the allowable residual pollution, and so on, in order to attain an optimum operation flexib- ility. Finally, the apparatus is highly seaworthy, in terms of ability to manoeuvre and of sea resistance. Further features and advantages of the method and apparatus according to this invention will become more apparent from the following description of some embodi¬ ments thereof, made for exemplary and non limiting purposes only, and referring to the attached drawing, wherein: Figure 1 is a general top schematic plan view of the whole apparatus; Figure 2 is a side view thereof; Figure 3 and Figure 4 are two schematic cross sections of the apparatus, taken at two different trims, as it is better described in the following; Figure 5 is a longitudinal section in a vertical plane of the part of the structure shown at B, made for instance along line V-V of Figure 3, wherein the components relating to a particular simplified version have been shown; Figure 6 illustrates more in particular the detail shown at E in Figure 5; Figure 7 is the same section of Figure 5, but it indicates operating components shown in more detail in a particular embodiment; Figure 8 shows a plan view of part B of the embodiment of Figure 7 ; Figure 9 is a schematic plan view of one of the hulls A, provided with a plurality of collected liquid decantat- ion tanks; and Figure 10 shows a cross section of a hull A, taken along plane W-W of Figure 9- The inventive apparatus is comprised of a floating structure including substantially five structural bodies among which there are two side hulls A of the assembly, located symmetrically relative to the longitudinal symmetry plane of the apparatus, which plane is shown in chain lines in Figure 1 , said hulls having a substant¬ ially elongated and narrow parallelepipedal shape, suitably tapered at the front and rear ends thereof. It should be noted that in the following description, the direction of the apparatus indicated herein towards the left side of the Figure by arrow F, will be defined "navigation direction", for non-operating transfer trips of the apparatus, while the opposite one, towards the right side of the Figure, shown by arrow F', will be defined "collecting direction" and the apparatus moves "astern" in the latter direction. Between side hulls A there are located three central bodies, and among the latter a body shown at B, or basin, being shaped as a generally parallelepiped tank with no lid, connected to adjacent bodies A in a non rigid, but in a vertically sliding fashion, by means of special guide means, with the possibility of being fast¬ ened in a particular position. Figures 3 and 4 schematically show two examples of different trims taken by the apparatus, with body B located at two different levels relative to the floating line LG, during navigat- ion and during a collecting operation respectively. Body C, or central hull, is located between the pair of side hulls A, in the region towards the navigation direction, and it forms the bow part during the transfer operation according to arrow F, while, together with said hulls A to which it is rigidly connected by means of disassemblable connecting means, it also forms known per se (not shown), /the main frame of the apparat¬ us which is driven by the pair of propellers shown at D in Figures 1 ans 2. Eventually, body M, which substantially accomodates machinery, controls, instrumentation, and so on, is connected to the other parts A and C of the hull, pre¬ ferably in a raised position relative to the latter. The five parts mentioned above may be disassembled from each other, and each one of them is so sized as to make the same normally transportable along roads. Bodies A are shaped in such a way as to create a minimum disturb¬ ance on the fluid flow ahead of basin B, i.e. In the collecting channel K. As it is shown In Figure 2, both bodies A extend vertically below the floating line in a lesser measure compared to body C, in order to contrib¬ ute to a wide floating figure with relatively reduced thrust. The weights of the apparatus are kept to a in particular minimum and/ those of the side tanks A are concentrated towards the center of gravity, in order to reduce the weight moment of inertia, while the floating surface is very much extended, in order to increase the geometrical moment of Inertia. In this way, it is enhanced the ready adaptability of the structure to the wave profile. In the embodiment of Figure 7, the floating figure is extended ahead (according to the direction of arrow F by blades 5 comprising the sliding bulkhead P of m Figure 5, whereby the center of gravity is displaced ahead in order to reduce the radius of the rotation the blades 5 or bulkhead P would be subjected to by the m structure oscillation relative to the waves, thereby reducing the immersion stroke that higher waves would produce thereon due to the rotation of the entire structure. The space wherein basin B is received is enclosed on the sides and in the navigation direction by the walls defining bodies A and C, which extend also above the floating line. In order to limit the internal wave mot¬ ion, the basin is divided in a plurality of cells extending for the whole depth thereof, and defined by vertical transverse bulkheads P , P ,... and longitud- ones inal bulkheads 14 (see Figure 8) the latter/ of which extend also above the floating line, while the trans- except for the (outer) one towards F, verse ones, /end below said line, and preferably at a height close to that of bulkhead P defining the basin in the working direction. Basin B is made vertically movable by known type actuat- ors (not shown) whereby it may be positioned where it is desired, as it is shown in Figures 3 and 4, being also possible, if the actuators are controlled by a suitable sensor, that the basin is positioned in a continuously variable position in order to follow the incoming wave profile. Referring now to Figure 5, concerning the first simplif¬ ied version of basin B, which is shown in longitudinal section therein, there is shown on the right the first of a plurality of transverse bulkheads, shown at P, whose upper edge is positioned at level which varies according to the vertical motion of a slidable part P , or sluice gate belonging to said bulkhead P. A sensor positioned outside and ahead of the basin, senses suitably in advance the variable height L of the incoming outer liquid, and adjusts, by means of automatically J controlled actuators, the level L2„ of Pm, whereby the difference L - L is as much as possible constant, having a value which can be determined each time by the operator. The blade of liquid having a thickness L - L , which flows over sluice gate P arrives inside basin B wherein m there is maintained an average level L , lower than L , (shown in Fig. 7) set by the operator by means of a high flowrate pump G through possibly adjustable suction ports F, located close to the bottom of the basin, at such a level as to ensure only water withdrawal, and therefore oil enrichment for the surface layer Immediately below level L . It should be noted that there will be provided at least a suction port F in each of the chambers formed within basin B by transverse bulkheads P , P , and so on, In communication with each other in the upper region through openings E, in order to provide progressively decreasing levels of the liquid surface towards the left starting from level L relating to the chamber defined by transverse bulkheads P and P . In the passage ment¬ ioned above, the liquid turbulence, or the motions thereof, are dampened by a device that, while not providing a relevant obstacle to the liquid flow direct¬ ed towards the left, above the threshold, substantially prevents a possible, even transient backward flow in the opposite direction, in the meantime adding to the dampening effect of the wave motion inside the basin. As it is shown in Figure 6, said device is preferably comprised of a rectangular sheet or "curtain" 0, extending along the whole threshold width, and preferably divided into a plurality of sections, both breadthwise and heightwise, which besides covering the whole threshold depth, extends also above the average floating level, preferably to a maximum level which can be reached by the liquid, in operation, above the threshold. Each one of the parts comprising said sheet is made of a very flexible, preferably thin and resil- ient material, substantially sealingly connected along one of the horizontal sides thereof, to a member R parallel to the threshold edge, and fixedly positioned relative to the structure, whereby sheet 0, or the entire assembly of flexible members comprising the latter and fixedly connected to points of the structure, when pushed by the flow overflowing the threshold to flex at right angles thereto, yields opposing only a negligible resistance (see Figure 6) and when it is pushed, for Instance by a wave motion internal to the basin, in the opposite direction, it is brought first to close the fluid passage above the threshold and then, once said position has been reached, It remains constrained thereto until there is a push in said direction, by means of suitable stops N provided for said purpose. Said stops will be such as to give enough flexible strength and rigidity to/sheet 0 resting against the sa¬ me, while not introducing any disturbance in the flow above the threshold, being for instance under the form of a plurality of stop abutments or of a stiff net having suitable wire and mesh size. In the latter chamber on the left there is provided a further transverse bulkhead of a variable height by means of sluice gate P manually or automatically settable in order to maintain the upper edge thereof at a level L., lower than the average level L of the liquid contained in the last chamber, wi h the difference L - L being determined by the operator. The automatic variation may take place through a motion coordinated in order to follow continuously and immediate- ly the liquid level instantaneously present in the last basin chamber, in order to eliminate or to strongly reduce the variations in the threshold immersion depth provided by the upper edge of sluice gate P for intake in a header I relative to the instantaneous level in that region of the basin, and consequently the variat¬ ions in the flowrate of the liquid overflowing from Pn into I, for admission to the subsequent treatment. In that way, in chamber I, which in the following will be defined "overflow header", possibly divided in the trans¬ verse direction, there sets up an incoming flow of an oil/water mixture, very rich in oil. The liquid entering header I is withdrawn through ports H, under a variable flowrate, in order to keep the surface between the levels r and L r , maximum and minimum 5 o respectively, at a level suitably selected and such that, relative to level L it is lower of a preferably small amount, in order to reduce to a minimum the un- avoidable turbulence induced by the overflowing, but in the meantime large enough to prevent substantial back- flows of liquid from the header to the basin, caused for instance by motions of the structure, or by a wave mot¬ ion possibly taking place within the basin. There is provided at least two ports H, one on the right and one on the left of header I, and each of them is connected by means of suitable diameter hoses to the respective flange, shown at X (Fig. 9) of the first tank included in said plurality of tanks U, located on the same side, and inside each one of the side hulls A. In the drawing, an array of twelve tanks has been shown. Each one of said tanks U, for both arrays, is in communication with the following one through passage slots located at the top and at the bottom, shown at Q and S respectively, as It is illustrated in Figure 10. In the last tank of each array, a suitable intensity of vacuum is provided in order to obtain total filling to the top of the twelve tanks with ' the liquid withdrawn from header I through ports H. The last tank of each array is provided with a raised dome, shown at Z in figure 9, on top of which there are provided pipes for oil and air suction, the automatic vacuum control mechanisms, and the liquid surface level indicators, all of them being already known. While the vacuum is maintained, also a total filling of the twelve tanks U with an oil/water mixture is maintained which, due to the long,slow,non turbulent crossing through the array of tanks, enables only oil to concentrate at the top, and only water to concentrate at the bottom. If water Is with- drawn from the lower part of the last tanks U, through flanges Y (Figure 9), the top portion of the same tanks will fill up with oil. The separation surface between water and oil will actuate, at a predetermined minimum position, the start and suction from dome Z, of an oil transfer pump, while the pump stop will be controlled by a signal derived from the maximum predetermined level of said surface. In fact, since the tanks communicate with each other also at the top, the oil/water separation surface comes to the same level in all the tanks U, and since only a single withdrawal position is sufficient for the suction of the collected oil, it will be possible to transfer the oil from the tanks even without interrupting the collecting operations. In addition, the fact that all the tanks are full of liquids, results in preventing both trim variations and reduction in stabil¬ ity which could reduce the speed with which the structure adjusts to the tallest waves, besides possible turbulence and shocks within said tanks. Oil withdrawal through tank Z can be performed by connecting the top portion of the tanks, by means of lines of pipe, ith a small sump, preferably provided at a lower level compared to the water level maintained with- in header I, whereby the oil can flow thereto even only under the action of gravity. From said sump the oil is withdrawn by means of a pump, controlled according to known techniques, by two level indicators in order to control oil transfer towards the final oil stocking containers, so that, when the amount of oil contained in tanks U goes over a certain value, one of the sensors actuates the transfer start, and when said amount falls below another predetermined value, the second sensor controls the transfer stop. As it should also be apparent, by maintaining a vacuuum within the array of tanks, the level of the liquids contained therein can be made to rise above the one previously indicated, and possibly even above the basin level, being then possible to increase the useful height of the tanks mainly In order to increase the decanting and stocking capacity thereof. In practice, in said raised dome Z on top of the last tank of each array in both hulls A, there is provided both the air suction outlet necessary to maintain said vacuum, and underneath the latter the collected oil withdrawal pipe, as well as the fittings for the level indicators and controllers. Furthermore, dome Z is also a liquid-filled volume which, a reservoir, compensates the level variations caused by changes in the incoming flow from header I, and by changes in water outgoing flow through bottom flange Y. Referring now to Figures 7 and 8, there is shown in more detail therein a preferred embodiment as an example of the simplified and more general form of basin B shown in Figure 5. P is still the front wall enclosing basin B on the front side, while the internal transverse walls are shown as 8. On the upper edge of P there slides an arc- shaped gate 1 , substantially like a portion of a cylinder surface, extending all the way towards the floating surface. Gate 1 is hingedly connected to a stationary transverse shaft 2 by means of arms 3, radially converging toward the latter. At the upper end of movable gate 1 there is pivoted, along a shaft 4 parallel to shaft 2, a blade-like or blade member 5 facing out from the basin, and in particular towards the region shown at K in Figure 1. In addition, blade 5 is rigidly connected to a system of floats 6(and of springs not shown in detail), which keep the floats submerged on the average for about one half of the volume thereof. In that way, blade 5 is kept in a horizontal position, at a predetermined level L < L , which can be set in advance by known means, already mentioned above, while describing the embodiment of Figure 5, with ample possib- ility to move vertically, as allowed by the hinged connection relative to shaft 2, below floating surface L . In such a way, the average thickness of the liquid layer L - L above blade 5 is kept relatively constant, independent of the wave profile. Any vertical translat¬ ion impressed to blade 5 causes therefore a correspond¬ ing motion of wall 1 which slides tangentially and substantially sealingly along the upper edge of first wall or bulkhead P. Therefore, on the one hand blade 5 is able to freely follow the wave motion while on the other hand a relative sliding is provided between wall 1 and the edge of the vertical gate, in a substantially sealed fashion, and without any relevant friction. The blade 5 and gate 1 assembly corresponds to the sluice gate P of Figure 5- Blade 5 is a member effecting a first separation of the liquid layer to be admitted to the basin, and it must remain substantially horizontal, while being able to perform vertical traverse motions, at right angles to the plane thereof, along part of an almost vertical circular path • required by rotation of the rear supporting body comprising gate 1. Stationary wall P shields the lower portion of member 1 from the dynamic pressure of the water in that the upper edge is located at a very short radial distance from the cylindrical surface of said member, in order to ensure a good sealing against the entrance in the basin of water passing between the movable member 1 and the stationary part P. It should be noted that the separating member, or blade 5, can be supported by a rear member 1 which, instead of having the shape of a cylindrical surface, has a substantially flat vertical shape, as shown schematical- ly at P in Figure 5, constrained to slide in a parallel m direction along stationary part P, with a minimum clearance, possibly providing known type seals, in order to improve the sealing action. According to a further embodiment , the motion of blade 5 may be different from the substantially vertical one permitted by float 6. In fact, said blade may be pivoted directly on the stationary structure, by means of a horizontal shaft transversely arranged relative to the liquid flow, along a side thereof, or along an internal axis which does not need to pass by the center of gravity in order to reduce to a minimum the unbalance induced thereon by the dynamical force deriving from the relative motion of the water. The depth of the pivot connection will be equal or close to the average separation distance required for the surface liquid layer and a known type connection will be provided to a control system adapted to swing the blade front edge according to the wave profile variations. Flexible and water-proof connections will be further provided between the pivot shaft and the frame, located in such a way as not to interfere with the blade swinging motion. In the embodiment of the invention shown in Figure 7, basin B is divided in four regions 7a-7d, by means of substantially vertical and transversely arranged bulk¬ heads 8 which extend from the basin bottom up to openings E in order to maintain continuity in the surface layer, with a simultaneous partitioning of the mass of water contained within basin B in order to reduce a possible turbulence or wave motion propagation. Close to the upper horizontal edge of bulkheads 8 there is provided substantially horizontal hinged flaps 9 which extend in such a way as to cover almost the entire width and almost a half of the length of the central regions 7b and 7c of basin B. Said flaps 9 are connected to known type damper means 10, for Instance piston damp¬ ers, in order to be able to oscillate at a predetermined average depth to dampen wave motions, while allowing the oil rich surface layers to pass thereabove. Damper means 10 absorb and dissipate part of the wave energy. Each flap 9 is arc shaped whereby, also in a disabled posit¬ ion, they do not have substantially any influence on the motions ot the overlying layers, while they hinder wave motions in the surrounding areas, and turbulence compon¬ ent coming from underlying layers. The anti-backflowing or unidirectional openings E provided at the top of each bulkhead 8 have already been described in detail referring to Figure 5 and, concern- ing the flexible "small curtains" 0, referring to Figure 6. Basin B, further provided with already described longitudinal bulkheads 14, in order to reduce to a minimum possible transverse wave motions, is provided with a bottom duct 11 , laid across said basin in the longitudinal direction, and having a front intake 12 and a rear outlet 13 provided on the rear wall or on the basin bottom. Close to duct 11 outlet 13 there is provided a pump means G performing liquid suction both from out¬ side through intake 12, and from inside regions 7a-7d through transverse headers F connected to duct 11 and provided on the bottom of chambers 7a-7d. Headers F and intake 12 may be suitably choked by known means, in order to control, according to need, the amount of water suction from outside or from the various chambers of basin B. To allow oil collecting operations to be performed also when the structure is at a standstill or proceeding at low speed, removable devices may be provid¬ ed, each one being preferably In the form of a length of elbow duct to be attached to the outlet 13, in order to subject the outcoming water to the proper amount of deviation, preferably in opposition among the jets, or downwards, so that the propulsion thrust acting on the structure, due to the jet exhausted by pump G through outlet 13, is neutralized. Within chamber 7b, where a higher concentration of oil has taken place, there is provided a flexible and water¬ proof hose 15 whose cross section is kept constant by means of a number of stiff horizontal rings wherein the one ring closest to the surface, shown at 15a in Figure 7, is connected both to a vertically slidable fastening member (not shown in the drawing) preventing a ring overturning in a horizontal plane, and to a float 16 provided to keep the hose intake at a predermined and adjustable level underneath free surface L, of the basin 4 or better of chamber 7b, according to operating condit¬ ions, whereby the liquid contained in area 7d continuously overflows into hose 15. Through the latter, under the action of gravity, the liquid reaches header I whereby it is subsequently subjected to the process previously described referring to Figures 5, 9 and 10. It should be pointed out that the above processing operations may be repeated sequentially, by performing liquid separation and withdrawal from the uppermost layers, while the lower ones are rejected, no longer on substantially undisturbed water, but on that portion containing the oil layer which has already been subject¬ ed to preliminary concentration during the first or the following sequential processing operations, and introducing the liquid, which has been separated and withdrawn, still in one or more subsequent basins, for slowing-down and separation, wherein there is possibly performed further operations comprising slowing-down, water ejection from below, and surface withdrawal of liquid having an increased oil concentration. As it was mentioned above, central basin B is connected to the structure by non-integral means, but through known type guides for a vertical sliding motion, in particular relative to the pair of side hulls A. Said motion may be provided through known power control means, both directed by the operator or by a signal taken from a dedicated sensor, whereby the vertical distance relative to the wave profile is not rigidly dependent upon the floating structure motion relative to the same profile, but may be adjusted continuously in order to reduce changes in said distance to a minimum. Said changes then substantially coincide, still referr- ing to the wave profile, with those of that structure portion where said blade or separating member 5 Is connected. Displacements of the latter will then be controlled only to eliminate or to reduce those variat¬ ions in the thickness (L - L ) of the liquid layer admitted to B caused by the minor wave motions and by that part of the major wave motion which has not been compensated by displacing the basin. Since the action of member 5 does not have any influence on the level difference which might be induced by the wave motion between the outside and inside of B, but is limited to track the same difference and to reduce the effect thereof on the thickness of the liquid layer entering the basin, said wave motion, for the part controlled by member 5, involves irregularities and turbulence in the incoming flow due to said level difference: controlling the displacement of the basin to track the major wave motion gives the advantage of eliminating said level difference, and therefore said irregularities and turbulence in the incoming flow. It should eventuallv be noted that the inventive apparatus is shaped and arranged in such a way as to be able to navigate and to manoeuver, during transfer trips wherein no oil collection is performed, in a direction opposite to that of the oil collecting operat¬ ions, whereby the member that during said operations performs the first separation between the surface layers of the surrounding body of water, i.e. blade 5, during said transfer navigation, is located substantially astern of said floating structure. On the other hand, the opposite end of body C, which during navigation comprises the bow, will be preferably shaped in such a way as to optimize the navigation qualities of the assembly concerning in particular speed and ability to vertically manoeuver. At the same time, since the basin is/movable, it may be brought to the height position which better suits said navigation qualities, and possibly completely or partially emptied of water. Additions and/or modifications may be made to the method and apparatus according to this invention, for oily waste and generally floating refuse removal, from the surface of bodies of water, as described above, without exceeding the scope of protection of this invention.

Claims: C L I M S 1. A method for removing from the surface of bodies of water oily matters and floating matters in general, briefly designated as "oil", characterized in that it includes, as a first action performed on the oil, while it is still floating substantially undisturbed on the water surface, the operation of preliminarly increasing the concentration thereof per unit of surface, relative to the initial concentration. 2. The method of Claim 1, characterized in that said preliminary concentration increasing operation is per¬ formed through the following elementary steps of: a) initially separating from the surface of the body of water a thin liquid surface layer of a minimum thick¬ ness, but still sufficient to certainly contain the whole amount of oil, simultaneously giving to the liquid of said separated layer such a relative velocity as to for¬ ward it to the following treatment with a minimum or no turbulence; b) introducing then the liquid of said separated layer into a basin whose size relative to the cross section where the separation has taken place is such as to substantially reduce said relative velocit2 of the liquid flow, whereby a decantation process is enhanced. I.e. a separation due to the density difference between the water, which sinks to the lower layers in the basin, and the oil floating substantially undisturbed there- above; c) withdrawing and ejecting the water from the basin lower layers through suction, whereby oil concentration in the top layers is increased; d) withdrawing from the basin surface, where the highest oil concentration is present, substantially water-free top layer liquid. 3. The method of Claim 2, characterized in that said water suction from the lower basin layers may be choked be and ejection thereof can also/used to cause relative mot¬ ion of said basin on the surface of said body of water, the ejected water forming at least one jet which can be directed in such a way as to take down to zero or to reduce the propulsion thrust thereof. 4. The method of Claim 2 or 3, characterized in that control is provided over the thickness of the liquid layer being separated and sent to oil decantation and concentration, whereby said thickness is kept down to a minimum still ensuring that the whole amount of oil is separated and introduced in said casin, by instantaneous¬ ly changing said thickness according to wave variations. 5. The method according to Claim 2, characterized in that said liquid processing steps are sequentially repeat¬ ed by performing liquid separation and withdrawal from the top layers, wherein a higher concentration of the oil layer is present τ due to previous processing operat¬ ions. 6. The method of one or more of Claims 2 to 5, characterized in that it includes, following said step d), a further operation wherein the liquids withdrawn from those surface layers having a higher oil concentration, are subjected to a further decantation process, for separating oil from the residual water, by passing them at low speed through an array of tanks communicating with each other, wherein a flow is maintain- ed from the first tank to the last, wherefrom the water deposited at the bottom is withdrawn and ejected, while the oil is in turn withdrawn and sent to stock, out of the top portion of said last tank. 7. The method of Claim 6, characterized in that oil withdrawal by suction from the last of said tanks is performed continuously and automatically, without any need to discontinue the collecting operations, using as a suction actuation signal the level reached by the water to oil separation surface within said tanks. 8. The method of Claim 5 or 6. characterized in that inside the whole array of said mutually communicating tanks there is drawn a vacuum through air suction from one of the tanks in the array. 9. An apparatus for removing, from the surface of bodies of water, oily matters designated in general as "oil", substantially comprising a floating structure (A, B, C, M) provided with propulsion means (D) permanently associated therewith, characterized in that it includes a substantially horizontally oriented separating device (P , 5) lying between two vertical intake walls, said m device being submerged in the water at a level (L ) lower than the surface (L ) of said body of water, the difference (L -L ) being a minimum and adjustable, provid- ed it is large enough to positively separate from the lower layers the whole layer of floating oil, a basin (B) in communication with said separating device and hav¬ ing a depth and a cross-section largely higher than the corresponding dimensions above said separating member, whereby the liquid flow entering therein is strongly slowed down compared to the relative velocity of entrance into basin (B), in the lower portion of said basin (B) there being provided suction ports (12, F) connected with suction means (G) and adapted to generate a water flow from the top towards a lower outlet ( 13) while keep- Ing, inside said basin (B) , an average level (L ) , means (P , I, 15) being further provided for withdrawing liquid from the surface layer inside basin (B) and close to the side thereof opposite to the one where said separating means are located, in order to send the with¬ drawn liquid, through an overflow header (I) , to an array of further decantation means (U) , towards final separat¬ ion and disposal, as well as means (8, 9, 14, 0) adapted to reduce the wave motion within basin (B) . 10. The apparatus of Claim 9, characterized In that said structure, In particular In the portion thereof closer to separating member (P , 5), Is adapted to follow variations in the wave profile, in that the weights thereof are reduced and concentrated, in order to keep to a minimum the overall weight moment of inertia of the structure, the floating surface is extended in order to raise the geometrical radius of inertia to a maximum, said structure being extended in such a direction as to take the geometrical center of gravity thereof to the position wherein, on the structure, there is located the separating member. 11. The apparatus of Claim 9 , characterized In that the basin is divided, in a transverse direction, in a plurality of complete components operating in parallel, without any communication possibility in the transverse direction; it is further divided, in the longitudinal direction, in a plurality of chambers (7a to 7c) which communicate at the bottom with said high flowrate suct¬ ion means (G) and at the top with the adjacent chamber which follows in the direction of the liquid flow or collection flow, the separating member between two ad¬ jacent chambers in the longitudinal direction being comprised of a bulkhead (8) rising from the basir. bottom all the way to slightly below the average filling line, to form a communication threshold (E) adapted to allow only the top layers, already enriched in oil, tc pass to the following chamber. 12. The apparatus of Claim 11, characterized in that it includes, at each threshold (E) , a device (0) , adapt¬ ed to substantially prevent any back ~ flow in the opposite direction, helping in that way also to dampen the wave motion within the basin, without hindering, in the meantime, the normal flow of the liquid stream above said threshold (E) . 13. The apparatus of Claim 12, characterized in that said device (0) comprises one or more rectangular sheets extending over the whole width of said threshold (Ξ) and for a height over the latter reaching above the average filling level (L ) , all the way to the maximum level the liquid can reach, said sheet being comprised of a flex¬ ible, inextensible, thin and resilient material, seal- ingly connected along one of the horizontal sides there¬ of to a member (R) parallel to the edge of threshold (E) and integral with the structure, the opening defined by said threshold (E) being provided with a series of net¬ like type supports (N) against which said sheet (0) gets stopped in case of any back—flow generated by wave motions within basin (B). 14. The apparatus of Claim 11, characterized in that It further includes devices (9, 10) adapted to dampen any longitudinal wave motion which might arise in the liquid contained In basin (B), within each chamber. 15. The apparatus of Claim 14, characterized in that each of said devices comprises a pair of flaps (9) both of which cover substantially the whole width of the respective chamber and have a length shorter than half the chamber width, located below the liquid free surface within the chamber, with one edge thereof located very close to separation bulkhead (8) and parallel tc threshold (E) , and pivoted along said edge in order to swing about a substantially horizontal inoperative posit- ion, each flap being connected to known type damper means shown at (10), adapted to dissipate the energy subtracted from the wave motion, in addition each flap being shaped in such a way as to be substantially unaffected by motions in the overlying layers, while it resists the wave motions in the surroundings. 16. The apparatus of Claim 9, characterized in that said separating member comprises the top edge of a flat vertical sluice gate (P ) , slidingly and sealingly mount- m ed relative to front wall (P) of basin (B) . 17- The apparatus of Claim 9, characterized in that said separating member comprises a substantially horizontal rectangular blade (5), pivoted on one edge thereof to a horizontal shaft (4) transversely arranged to the flow, and a body (1) positioned behind said blade, having a substantially cylindrical surface connected by means of radial members (3) to a pivot shaft (2), parallel to said shaft (4) and integral with the struct¬ ure, said blade (5) being connected to known means (6) adapted to keep it in a substantially horizontal posit¬ ion and at a constant and predetermined depth, whereby the blade motion is substantially always a vertical traverse motion, and such as to transmit a rotation about said shaft (2) to said body (1), which is constant- ly in contact with the upper edge of said front bulkhead ( P ) . 18. The apparatus of Claim 9, characterized in that said first separation member (5) comprises a rectangular blade directly pivoting on the structure, about an axis parallel to a transverse side thereof, at a depth equal or close to the desired average separation depth, a connection with driving means being provided in order to swing the front edge of said blade (5) for changing wave profiles, there being further provided a flexible and waterproof connection between said pivot shaft and the structure, in order not to interfere with the swing¬ ing motion of said blade, and to ensure a substantially complete sealing. 19- The apparatus of Claims 16 to 18, characterized In that the position of said separating member (P , 5) adapt¬ ed to determine said level (L ) is controlled at any moment depending upon the wave profile, by means of known automatic controls. 20. The apparatus of Claim 9, characterized in that said withdrawal means for the liquids to be sent to further decantation and final separation means (U; comprises at least one substantially vertical tube-like header (I) ending, at the top thereof, with a horizontal edge positioned at a controllable level (L^ ) , slightly lower than the average level (L ) established in the last basin chamber (7 , and in communication, at the d opposite end thereof, through a port (H), with the first, on each side, of an array of decantation tanks (U). 21. The apparatus of Claim 20, characterized in that said header (I) has a top part (15) comprising an extens¬ ion having fixed transverse dimensions and a widely variable vertical dimension, such as a flexible and waterproof hose, stiffened by transverse mutually spaced rings, and ending at the top thereof with a section (15a) fastened in such a way as to remain, on the average, horizontal and submerged of a small and adjustable amount (L -L ) relative to the basin free surface within said chamber (7d), by means of a float arrangement ( 16) . 22. The apparatus of Claim 21, characterized in that the liquid level within said header (I) is kept at a height ranging between a minimum level (L ) and a D maximum level (L_) , owing to the exhaust flow through 5 said port (H) and to the immersion depth (L ) of said top edge (15a) which is adjustable depending upon the wave motion, forming a minimum level difference with said level (L-,) sufficient for preventing any back-flow of liquid from the header into the basin, there being possibly provided automatic controls adapted to track continuously and immediately said instantaneous level within chamber (7d). 23. The apparatus of Claim 9, characterized in that said further decantation and concentration as well as final separation means comprise at least one array of serially arranged tanks (U) communicating with each other in their lower part through ports (S) , the first tank of each array communicating, through a passage (X) in the lowermost part thereof, with said header (I) , while the last tank in the array is in communication, at the lower side thereof, with the suction (Y) of a water ejection pumping means, there being further provided means to withdraw the oil collecting in the upper part of the tanks, above the water flow. 24. The apparatus of Claim 23, characterized in that said tanks (U) of each array communicate with each other also in the top part thereof, whereby the water to oil separation surface gets to the same level in all the tanks, and therefore a single withdrawal point is sufficient to perform the suction of the oil collecting in the top part of the tanks. 25. The apparatus of Claim 23, characterized in that each tank (U) of said arrays is closed at the top, with air vents provided with check valves, and it is kept completely full of liquids, means being provided to per- form air suction at the last tank of each array. 26. The apparatus of Claim 23, characterized in that said oil withdrawal means comprise a pump drawing from a sump wherein the oil coming from the top part of tanks (U) collects, said pump being automatically controlled by two level sensors, one of them actuating the oil transfer when the amount of oil contained in the tanks exceeds a certain value, while the second sensor stops the transfer when said amount has dropped below an¬ other predetermined value. 27- The apparatus according to one or more of Claims 23 to 26, characterized in that one tank of each array is provided with a raised dome (Z) wherein there is provided both the air suction port to generate the vacuum within the system and, below the latter, the collected oil withdrawal tube, as well as fittings for level indicators and controls, said dome (Z) comprising as well a volume filled with liquid and adapted to compensate, in a reservoir-like fashion, the level variations. 28. The apparatus cf Claim 9, characterized in that said high flowrate suction means (G) comprise the same propellers (D) for structure propulsion, and in that, at the withdrawn water ejection ports (13), removable devices may be provided in order to deviate the jet or the jets, to take the corresponding propulsion thrust down to zero. 29- The apparatus of Claim 9, substantially divided into independent and mutually connected parts, each one of them having such dimensions as to allow the same to be transported along roads, including a central part comprising said basin (B) containing all the internal components; two symmetrical parts or side hulls (A) sub¬ stantially containing the further decantation and final separation tanks (U); a part (C) comprising the central portion of the hull, located between the two side hulls (A) on the side of the transfer direction relative to said basin (B) , adapted to comprise, with said side hulls (A), the actual structure of the hull; and a fifth part (M) wherein there is substantially received the machines, controls and instrumentation, located in a central position on top of the parts mentioned above, said parts (A) and (C) being shaped in such a way as tc provide the apparatus with good seaworthiness qualities when it navigates without performing an oil collecting funct- ion, said parts being further positioned in such a way as to define therebetween the room adapted to contain said basin (B), allowing for displacement thereof between an upper fixed position during transfer navigation, and a second lower movable position, during oil collecting operations . 30. The apparatus of claim 29 . wherein said basin (B) is vertically movable with respect to the structure as it is slidably mounted on side guides to hulls (A) and driven by known means responsive to the major wave motions , hereby the changes of the distance of average level (L ) in the basin from instantaneous wave profile is minimized.

Inventors: DE TOFFOLI MIRELLA, DE TOFFOLI, MIRELLA
Applicants: MITILUS S R L, MITILUS S.R.L.
Application year: 1989
Main classification: E02B15
IPC codes: E02B15