CA1194811A

CA1194811A - Method of and device for skimming off substances floating on water

Info

Publication number: CA1194811A
Application number: CA000384049A
Authority: CA
Inventors: Dietrich Sobinger
Original assignee: Individual
Current assignee: Individual
Priority date: 1980-08-21
Filing date: 1981-08-17
Publication date: 1985-10-08
Also published as: ZA815461B; PT73551B; BE890029A; WO1982000671A1; EP0058179B1; IT1143412B; PT73551A; DK174682A; EP0058179A1; IT8149127A0; DE3172235D1; JPS57501293A

Abstract

Abstract This invention relates to a method of skimming of substances floating on water, especially oil, whereby the skimmed-off substance-water mixture is collected and, after a specific settlement period, the substance is sucked off and the water together with the substance situated on and/or beneath the water surface is conducted onto an ascending inclined surface and, during and/or after its ascent up this inclined surface, is collected.

Description

3 ~9'~L~;33.~L

Method of and Device for skimming off substances floating on water The present invention relates to a method of skimming substances floating on water, especially oil, whereby the skimmed substance-water mixture is collected and, after a specific settlement period, the substance is sucked off. The present invention furthermore relates to a device, especially for carrying out this method.

Due to oil tanker wrecks and accidents in drilling in the sea large uncontrollable quantities of oil are increasingly entering the sea, causing serious environmental damage and high costs for cleaning again the oil-contaminated regions of the land and water. Moreover, great ecological harm also arises therefrom. Oil pollution in harbour installations and lock installations also give rise to considerable costs. The difficulty of again collecting oil which has uncontrollably escaped lies on the one hand in the fact that oil rapidly spreads over large areas and, in many cases in quite unforeseen manner, is also driven by the influences of currents and winds. In addition, the motion of the sea frequently makes the skimming of oil extremely difficult and, when the waves are exceptionally high, there is at present practically no possibility at all of collecting floating oil. For skimming oil slicks from bodies of water, it is already known to construct types of ships which possess a longitudinally divisible hull opening so to speak in the manner of a beak and which are equipped with pumping units for sucking away oil and storage tanks for the sucked-off .
..

oil. The skimming performance of such ships is very limited, because the storage tanks must receive not only the sucked-off oil but also the water removed with it. Added to this is the fact that ships of this type can cover only a limited area and, as a consequence of their longitudinal division, are very difficult to employ in a rough sea, especially when opened in the manner of a beak. Moreover, ships of this type are not suitable for forming fairly long oil barriers in order to obtain an enclosed region of large area for oil slicks.

The task underlying the present invention is to create a method and a device for the skimming of subtances floating on water, especially oil, by which it shall be possible in a simple and functionally appropriate manner to obtain high skimming performances even in a strong water current or rough sea.

According to the invention this task is achieved in that the water~ together with the substances situated on and/or beneath the water surface, is conducted onto an ascending inclined surface and, while and/or after it is running up this inclined surface, is trapped. The invention is based upon the knowledge that the subtances to be skimmed situated on the surface do not mix with the ascending water as they run up the slope and are floated up the slope with only a limited quantity of water. Thus a first separation and reduction of the water quantity compared with the substances to be collected is carried out during the trapping, since only the uppermost layers of water are ",~''-1 collected together with the substances floating on the surface. Consequently, according to the present invention, a skimming is achieved with a relatively small proportion of water without any suction measures. Especially in a heavy sea the invention is of advantage, because a continuing weakening of the wave energy is obtained corresponding to the slope by the running-up. The invention provides the advantageous possibility, by varying the running-up distance and/or the running-up angle, of achieving the optimum skimming as a function of the particular run-up speed and/or the height of the waves. Particularly in a fairly strong current and high waves, a staggered or step-shaped collecting oF the substances floated up the inclined surface can be carried out.

The present invention furthermore relates to a device for skimming substances floating on water, especially oil, consisting of a floating object as collecting vessel for the substance-water mixture and suction devices for the substances separated From the water. Basically, devices for separating water and oil are known, which consist of a vessel chamber for receiving the water-oil mixture~ from which, after a certain settlement period, the oil is sucked up from the surface of the water by suction devices.

Reference can be made in this context, for instance, to DE-OS 23 16 840. Starting from the known receiving vessels and the initially described devices for the skimming of subtances floating on a water surface, especially oil, the task underlying the present invention is to create ,,. :~.

a device which possesses a high skimming performance even in a heavy sea, and which moreover possesses a comparatively simple and functionally appropriate form of construction and can be used economically and is also suitable for constructing an oil barrier.

According to the invention this task is achieved in that the floating object possesses at least one run-up surface inclined to the water surface, in which at least one collecting openirg is disposed above the water line of the floating object, this opening being connected with the internal space of the collecting vessel. It is especially appropriate here if the run-up surface extends upwards from the bottom of the floating object. As a consequence, the commencement of the run-up surface is always situated below the water surface, with the result that the decelerated wave which forms is displaced well forward on the run-up surface and is reduced, so that the substances to be skimmed can surmount the wave unimpeded. Furthermore, this run-up slope commencing below the water surface is advantageous because substances are also trapped by it which are situated beneath the water surface.

In this connection, one especially simple embodiment of the device of the invention, which is suitable especially for use in enclosed or sheltered waters with relatiYely low waves~ consists in the fact that the collecting opening extends across the entire width of the run-up surface at the end thereof and the collecting chamber is in direct communication with the body of water through , ....

~9~
an opening in the bottomO

At fairly high current speeds and in fairly rough water, it is especially advantageous if a number of slit-shaped collecting openings are disposed on the run-up surface at distances one from another and one above another.
Here the arrangement may be such that -the upper collecting openings are disposed above the intermediate spaces between the lower collecting openings. By this arrangement according to this invention and construction of the collecting openings, complete skimming of the entire floated substances is achieved and a build-up due to components that might flow back is prevented.

By the fact that, in a further embodiment of the invention, a slit-shaped collecting opening extending across the entire width of the run-up surface is formed as the foremost collecting opening, which opening then adjoins the above-described arrangement of individual collecting openings, a device is created which can be used to the optimum both in calm and in rough water.

Further advantageous embodiments of the collecting openings are described in sub-claims 10 and 11.

It may furthermore be advantageous for the collecting vessel to posses a floodable double bottom and/or floodable side gangways. By the flooding of the double bottom and side gangways the waterline of the floating object or pontoon can be varied at a predetermined draft. The !:, ' pontoon is lowered in the water by flooding of the double bottom and gangways and the draft can be reduced by pumping them out. The draft depends here upon the desired distance between the first overflow edge of the collecting openings and the water surface and this in turn is selected as a function of the wave motion the speed of flow and the desired oil surface level of the settled oil in the collecting vessel. For example~ for a flow speed of lm/sec.
the draft is so adjusted that it is necessary to surmount a height of approx. 70mm to reach the first overflow edge of the collecting openings.

By means of the floodable and pumpable gangways and double bottom it is also possible to keep the draft constant as a function of the quantity of oil/water mixture collected in the collecting vessel so that the double bottom and gangways are emptied or pumped out in the same manner as the collecting vessel fills up i.e. the pumped out quantity of water corresponds in weight to the quantity collected in the collecting vessel. By means of them it is also possible to produce a variation in the run-up angle by varying the filling of the oppositely situated tanks.

Further advantageous forms of embodiment of the invention are contained in sub-claims 15 to 23.

The invention is explained in more detail with reference to the examples of embodiment illustrated in the attached drawings. The drawings show:

..

Fig. 1~ a side view in section of a device according to this invention, Fig. 2, a plan view on a device of this invention according to Fig. 1 with an alternatively constructed run-up surface, Fig. 3, a side view in section of a further form of embodiment of a device according to this invention, Fig. 4, a plan YieW on the device according to FigO 3, Fig. 5, a plan view on a plurality of devices according to Fig. 3 connected together in ar-ticulated manner.

As can be seen from Fig. 1, a device according to this invention consists of a floating object or pontoon 1, which possesses an ascending inclined surface or run-up surface 2, which makes an angle of slope c~ with ~he lower edge or bottom 3 of the pontoon. This means that the run-up surface 2 extends to the lower edge of the pontoon, so that when the pontoon is in operation ~he run-up surface 2 is always situated with its forward portion beneath the water surface 4, causing a built-up wave to be displaced forwards as far as possible along the run-up surface 2~ The flow direction of the oncoming wa~er is indicated by the arrow X.
The running-on of the water onto the run-up surface 2 can be produced on the one hand by a movement of the pontoon 2 in the direction of the arrow Y or, by the pontoon 1 remaining stationary and the water running up solely by a corresponding flow of the water in the direction o~ arrow X. The . -running-up of the water may also be produced by both effects simultaneously. A collecting opening 5 is formed in the inclined surFace 2. In the example illustrated this is a collecting opening 5, which advantageously extends across the entire width of the inclined surface 2, the inclined surface

2 terminating v-irtually at the forward edge or overflow edge 6. In the example illustrated, the collecting opening 5 is connected directly with the internal space of a collecting vessel 70 Now if a layer of substances to be skimmed off, especially an oil layer, is situated on the water surface 4, then the oil-water mixture flowing over the overflow edge 6 is collected in the vessel 7. Furthermore, the device of this invention possesses a pump unit 8, which serves for sucking off the oil or substance settled on the water in the internal space of the vessel. The internal space of the vessel is connected with the external water directly via an opening 7a 9 which produces an automatic adjustment of the water level in the internal space to the average water level between the wave crests and troughs. The oil sucked off via the pump 8 is pumped into one or more storage tanks 9. It also lies within the scope of this invention, however, for the device of the invention not to possess itself such storage tanks, but for such storage tanks to be disposed, for example, in a tug which pushes the pontoon 1 or, in the case of a device according to this invention which is stationary 9 to be disposed outside the pontoon. A connection between the pump unit 8 and the storage tanks can then be provided by means of a flexible hose.

The device of this invention furthermore possesses floodable and pumpable wall gangways lO and a likewise floodable and pumpable double bottom ll. By means of the double bottom ll and the gangways lO, the draught or inclination of the pontoon l can be set on each occasion.

The pump unit 8 is disposed in an engine room l2.
A drive unit, not illustrated~ for the pontoon of this invention may also be provided in this engine room for driviny one or more propellers l3. It does however also lie within the scope of this invention for the pontoon l not to be self-propelled. A centrifuge l4 and/or an adsorption-coalescence filter may favourably be disposed after the pump unit 8, in order to ensure complete separation of the sucked-ofF oil from a certain residual quan~ity of water.

In Fig. 2, an alternative form of embodiment of a pontoon according to this invention is illustrated, components like those in Fig. l being allocated the same references. Here the run-up surface or inclined surface 2 is equipped with a plurality of collecting openings l6, l7. The Foremost collecting opening l6 is formed as a slit which extends across the entire width of the inclined surface 2.
In the run-up direction behind this collecting opening 16 there are situated a plurality of slit-shaped collecting openings 17, disposed alongside and above one another. These collecting openings l7 are disposed alongside and above one another in such a manner that the higher collecting openings in each case are disposed above the intermediate spacings between the lower collecting openings~ Instead of a _ g ~i~i 3~

combination of a continuous forward slit with staggered collecting openings 17 disposed behind it, such collec~ing openings 17 may also be distributed exclusively over the entire inclined surace 2, whereby a forward region o-F the inclined surface is always free of openings. The indi~idual openings 5, 16 or 17 can be constructed adjustable in their size.

In Fig. 3 a further embodiment of a device of this invention is shown once again like components bearing the same references as those in Fig. 1.

Here collecting pockets 20 are formed in the inclined surface 2, in which pockets the oil floated up with the water or the substances floated up with the water are skimmed off. The collecting pockets 20 are connected by means of extraction pipes 21 with the pump unit 8.
Consequently, no central collecting vessel is provided here, but instead a large number of collecting vessels which are formed by the collecting pockets 20. Each collecting pocket 20 possesses in turn collecting openings 22, which may be formed corresponding to the collecting openings 16, 17 in Fig. 2. The collecting pockets 20 are, in the example illustrated, disposed in the manner of a stair above one another and/or staggered from one another in the inclined surface 2. The collecting pockets 20 and/or the extraction pipes 21 may be heated by means of a heating plant. The heating plant is then connected to a steam boiler comprising a waste oil burner, which is not illustrated in detail. The substance-water mixture is pumped through the extraction ~: - 1 0 ;-, ;.1~ .~.

~ 9 ~
pipes into tanks 23, where the settlement process takes place. These tanks 23 may be connected with the external water via an opening either directly or through shut-off valves.

In the examples illustrated, a constant slope oF
the inclined surface 2 is shown. It also lies within the scope of this invention, however, not to make the slope constant but to make it variable along the inclined surface.
Thus, for example, there may be a steeper slope initially in the starting region, then a reduced, continuous slope which then changes at the end of the run-up surface again into a steeper slope. It is also possible to provide at the start of the run-up surface a shallower slope than in the central region, in order then to choose again in the end region a slope which is steeper than the central region. Slopes in the range of 1:10 to 1:~ are appropriate.

As can be seen particularly from Fig. 4, where once again components like those in Fig. 1 to 3 are allocated the same referencesg the pontoon 1 is constructed as an elongated object, one wide side being formed by the inclined surface 2 and the engine room 12 being constructed on its other wide side. The wall gangways or ballast tanks 10 are disposed at least on both sides above the longitudinal side of the pontoon 1. The ends of the pontoon are, in the example illustrated, formed as corresponding domed ends 23 in the manner of ball and socket seatings, to enable a plurality of pontoons 1 according to this invention to be connected together to form an oil barrier, as illustrated in :
....'.~ ;

FigO 5. As already explained9 the pontoon 1 is equipped with drive propellers 13 to improve its manoeuvrability, and also possesses anchors 24, on the wide side opposite to that of the drive propellers. This form of embodiment oF the invention enables a plurality of pontoons according to the invention to be coupled to one another or in a row to form an oil barrier or boom of virtually unlimited length, namely as a function of the size of the oil slick to be skimmed off.

The advantages achieved by the present invention are to be seen basically in that a device for skimming substances floating on bodies of water9 especially oil slicks~ is realized~ which is distinguished by an especially high skimming performance and even in a very rough sea. A
simple form of construction is here realized, in which there are no units that are liable to fail by wear. Thus the device according to this inven~ion is suitable particularly for use at seaO It should be noted here that high waves do not impede the skimming action, since the oncoming waves can run up ~he appropriately ad3usted run-up surface comprising the collection openings. Moreover, the device according to this invention can be used particularly economically. Thus9 for example, various devices according to this invention may lie at anchor at lengths of the coast particularly subject to risk and in the case of a castastrophe can be brought by tugs to the location of ~he accident. As a consequence of the elongated form of the pontoon of this invention, a length of up to 100 m for instance can be realized, so that it is possible even with a few such devices to cut oFf reliably any oil tanker wreck or borehole which has sufFered an accidentO

The device of this invention is simple to operate and requires in its use practically no specially trained personnel for its operation. Furthermore, it is also not necessary to occupy it permanently. The loading capacity of the device according to this invention can be designed so that the value oF the skimmed-off oil, taking account of present-day oil prices, at least balances the costs of use during an oil accident and can be financed by this sum. This is true also for larger oil castastrophes, even if the loading tanks then have to be discharged from time to time.
The device according to this invention can be used both at sea and in enclosed waters and on rivers.

~, .~ . ~,

Claims

THE EMBODIMENTS OF THE INVENTION IN WHICH AN EXCLUSIVE PROPERTY
OR PRIVILEGE IS CLAIMED ARE DEFINED AS FOLLOWS:

1. Method of skimming off substances floating on a body of water, especially oil, whereby the skimmed-off subtance-water mixture is collected and, after a specific settling period, the substance is sucked off, characterized in that the water, together with the substance situated on and/or beneath the water surface, is conducted onto an ascending inclined surface directly in the body of water and, during and/or after its run-up onto this inclined surface, is collected.

2. Method according to Claim 1, characterized in that the running-up water with the substance is collected by stages.

3. Method according to Claim 1 or 2, characterized in that the run-up path and/or run-up angle is selected as a function of the run-up speed and/or the height of the waves of the water.

4. Device for skimming substances floating on a body of water, especially oil, consisting of a floating pontoon as collecting vessel For the substance-water mixture and of sucking-off devices for the substance separated from the water, characterized in that the pontoon possesses at least one ascending inclined surface inclined and extending directly into the water surface, in which at least one collecting opening is formed above the water line of the pontoon which collecting opening is connected with the interior of the collecting vessel.

5. Device according to Claim 4, characterized in that the inclined surface extends from the bottom of the pontoon upwards.

6. Device according to Claim 4, characterized in that the collecting opening (5) extends across the entire width of the inclined surface (2).

7. Device according to Claim 5, characterized in that a plurality of slit-shaped collecting openings (17) are disposed at spacings alongside and above one another in the inclined surface (2).

8. Device according to Claim 7, characterized in that the collecting openings (17) are staggered one above another in such a manner that the upper collecting openings in each case are disposed above the intermediate spaces between the lower collecting openings.

9. Device according to Claim 7, characterized in that, as the foremost collecting opening, a slit-shaped collecting opening (16), extending across the entire width of the inclined surface (2), is formed.

10. Device according to Claim 4, characterized in that the collecting openings (5, 16, 17, 22) are formed adjustable in their aperture size.

11. Device according to Claim 7, characterized in that collecting openings (22) are disposed in the inclined surface (2), which are each connected with collecting pockets (20), which are connected via extraction pipes (21) and a pump (8) with the receiving tank (23) for the skimmed-off substance.

12. Device according to Claim 11, characterized in that the collecting vessel (7) or the receiving tanks (23) are connected with the external water by an opening (7a).

13. Device according to Claim 4, characterized in that the pontoon (1) is formed variable in its depth and angle of immersion.

14. Device according to Claim 13, characterized in -that the pontoon (1) possesses a floodable double bottom (11) and/or floodable compartments (10).

15. Device according to Claim 4, characterized in that the angle of slope ? of the inclined surface (2) is constant.

16. Device according to one or more of Claim 4, characterized in that the ascending inclined surface (2) comprises regions of differing slopes.

17. Device according to Claim 4, characterized in that the pontoon (1) is constructed as an elongated object having an ascending inclined surface (2) formed at its one wide side and having an engine room (12) formed at its other wide side and possesses compartments (10) at least on both sides.

18. Device according to Claim 4, characterized in that the pontoon (1) possesses, at its longitudinal ends, articulated joint-type connecting devices (23) for connecting a number of pontoons (1) together.

19. Device according to Claim 4, characterized in that the pontoon (1) is equipped with auxiliary drives (13) and anchors (24), whereby the auxiliary drives are disposed preferably upon the wide side opposite to the ascending inclined surface (2).

20. Device according to Claim 11, characterized in that collecting pockets (20) and extraction pipes (21) are heatable by a heating plant.

21. Device according to Claim 20, characterized in that the heating plant possesses a steam boiler with waste oil burner.

22. Device according to one or more of Claim 4, characterized in that a centrifuge (14) for substance-water separation is disposed behind the pump unit (18) for sucking off the substance to be skimmed from the collecting vessel (7) or the collecting pockets (20).

23. Device according to Claim 4, characterized in that a storage tank (9) for the skimmed-off substance is contained in the pontoon (1).