NL1022854C2 - Method and device for cleaning beaches. - Google Patents

Description

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Title: Method and device for cleaning beaches

The invention relates to a method for cleaning beaches. More in particular, the method relates to minimizing the amount of sand discharged thereby. !

Beaches are increasingly being contaminated by washed-up oil from sunken or leaked tankers. This oil comes into contact with the seabed during the washing up, due to the rolling movement of the waves near the tide line and thereby becomes mixed with sand. The oil-sand conglomerates thus formed are removed during a cleaning action, usually together with an upper sand and / or pebble layer of the beach, since impurities can also be present therein. The removed material, which usually contains more than 50 percent sand, is then disposed of as chemical waste and incinerated. The large proportion of sand is unfavorable for the incineration plant and moreover drives up the costs, because all this sand has to be transported and the incineration costs are moreover calculated per unit weight.

Moreover, a quantity of sand is thus lost with every cleaning operation, which is unfavorable for environmental reasons.

Another type of 'beach pollution' that occurs more and more often is large amounts of washed-up (sea) algae and / or algae. These 20 'contaminants' are removed from the beach in the same way as the oil, and then burned, since the waste is not is considered as biological waste. Again, the percentage of sand in the removed waste is relatively high, with all the aforementioned disadvantages.

The invention has for its object to provide a method for cleaning beaches, of contaminants left behind or washed ashore, in particular oil and / or (sea) seaweed. In particular, it is an object of the invention to provide such a method, wherein the aforementioned drawbacks of the known methods are avoided by the 1 Π O Λα -.

2 to minimize the share of sand in the contaminated waste material to be removed.

A further object of the invention is to provide such a method in which the sand is separated from contaminants present in the sand in an environmentally friendly manner, without the addition of chemical aids.

A further object of the invention is to provide a method in which the separation as well as the supply and removal of contaminated or purified sand can take place continuously, whereby relatively large quantities of contaminated sand can be processed within a reasonable period of time.

It is a further object of the invention to provide a method with which sand and contaminants can be separated from each other with relatively little energy, whereby the method can be easily carried out on or near the beach, whereby extensive logistical operations can be avoided and purified sand can be directly placed on the beach. refunded.

These and further objects are at least partially achieved with a method according to the invention, characterized by the features of claim 1.

In a method according to the invention, use is advantageously made of the fact that the specific weight of sand is greater than that of water, and that of the contaminants, on the contrary, smaller, so that the sand will settle in water and the contaminants will float. . Thus, the sand and the contaminants can be separated from each other, without chemical addition and with minimal energy, by means of gravity. The continuous supply and removal of contaminated or cleaned sand and contaminants ensures a relatively large processing capacity, whereby relatively large volumes, in particular a few tons of sand, can be cleaned per hour.

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In an advantageous embodiment, a method according to the invention is characterized by the features of claim 2.

Tests by the applicant have shown that, especially when the contamination concerns oil, a faster and more complete separation can be achieved by mixing the sand and the oil into a homogeneous mixture before the mixture is introduced into the settling tank wherein the water between the settled sand layer and the floating oil layer comprises substantially no floating oil flakes.

The mixing can for instance be carried out with the aid of a screw mixer 10, which is at least partially surrounded by a pipe part, so that the mixture between the edges of the screw and the inside of the pipe part is ground and mixed into a homogeneous whole. The screw mixer is preferably hollow, without a central axis, so that stones, cans and similar contaminants can pass through the screw mixer 15 to an outlet opening, without damaging the cutting edges of the screw. Of course, such contaminants can also be removed from the sand with the aid of suitable filtering means, in particular a coarse dirt filter, prior to being supplied to the mixing unit. The mixing unit is furthermore designed in such a way that the mixture can hereby be supplied to the settling tank in a continuous flow.

In a further advantageous embodiment, an amount of water is additionally supplied during mixing, which in the case of the contamination oil is preferably heated, so that the viscosity of the oil increases, and a relatively liquid mixture is obtained. The water in the settling tank is also preferably heated, for example to about 40 ° to 60 °. This prevents flaking of the oil in the water and promotes the overall segregation process, according to the applicant's tests.

In yet another advantageous embodiment, a method according to the invention is characterized by the features according to claim 8.

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By generating such eddy currents in the settling tank, the separated contaminants can be led to an outlet of the tank while, moreover, the separation process in the settling tank is thereby influenced, for example, accelerated. Other parameters with which the quality and / or speed of the separation process can be influenced are the temperature of the water and the residence time in the settling tank, which can be controlled by a proper alignment of the incoming and outgoing streams (contaminated sand mix and cleaned sand mix).

The invention furthermore relates to a device for cleaning sand from contaminants present therein, in particular oil and / or algae, characterized by the features of claim 12.

With such a device, sand and contaminants can be separated from each other in an environmentally friendly manner, without the addition of chemical agents and with relatively little energy, while, moreover, large volumes can be processed by continuous supply and removal of contaminated or cleaned sand. .

In a further advantageous embodiment, the settling tank is provided with first winding means, which generate a circulating current in the tank, around a substantially vertical axis. This promotes the separation process and moreover ensures that contaminants floating on the water are led to second discharge means, which can for instance be designed as a drainage gutter.

In a particularly advantageous embodiment, the first toiling means are designed according to the measures according to claim 15.

The angular cross-section will thereby generate turbulent eddy currents, which have proven to be advantageous for the separation process. Moreover, the contaminants will be driven outwardly in the radial direction by the rotating movement and an outlet will be created in the contamination layer floating on the water surface by draining contaminants via the second discharge means just behind these means, seen in the direction of rotation. Mixture from the mixing unit can be fed continuously through this opening into the settling tank without coming into contact with the contamination layer or having to penetrate it.

Furthermore, second tossing means are preferably provided for introducing upward eddy currents into the settling tank. This makes it possible to prevent relatively small oil particles from being dragged down by the sinking sand.

In a further advantageous embodiment, a device according to the invention is characterized by the features of claim 19.

When air lifting means are used, an underpressure is generated in a discharge pipe coupled to the settling tank, whereby sand is sucked out of the settling tank. As a result, the sand can then be transported upwards in the discharge pipe. Sand can thus be discharged from the device with minimal energy and in a controlled manner. The air lift means are furthermore clean and relatively simple and robust in construction and therefore extremely resistant to the harsh conditions under which the device according to the invention operates, that is to say sand and / or salt water.

In a further advantageous embodiment, the device is of mobile design, so that it can be used directly on the beach. As a result, no transport of contaminated and cleaned sand is required, and the associated energy and costs are therefore saved. The recovered sand can be returned directly to the beach. The water required for the operation of the device is preferably taken from a water mass adjacent to the beach, with suitable pumping means, it being irrelevant whether it concerns fresh or salt water. Moreover, the water used is recycled as much as possible. Since no chemical aids are added, the water can be returned to the water mass after use, 4 Λ Λ Λ λ λ 6, possibly after purification of possibly still dissolved impurities.

In the further subclaims, advantageous embodiments of an apparatus and method according to the invention are shown.

For clarification, a device and method according to the invention will be further elucidated with reference to the drawing. Therein, the one figure shows, in partly cross-sectional side view, a device indicated with reference numeral 1 for purifying sand 10 contaminated with contaminants, in particular oil. To that end, the device 10 comprises a conveyor 3, which with a first end under a coarse dirty filter 2 is located and with a second end above a mixing unit 5. The mixing unit 5 connects with input means 11 provided near an upper side 8 of a funnel-shaped settling tank 6, the settling tank 6 is filled with water in use. Near an underside 9 of the settling tank 6, first discharge means 12 are provided for discharging sand settled in use in the settling tank 6. Near an upper side 8 of the settling tank 6, second drain means 14 are provided, for drainage of oil floating on the water surface in use. These second discharge means 14 open into a collecting reservoir 15, for collecting said oil and water entrained with the oil. A so-called skimmer 18 is provided above the collecting reservoir 15, with which the oil layer is scraped or driven from the water. Such a skimmer 18 is generally known and will therefore not be further described here. The collection reservoir 15 is connected via a return line 16 to a water tank 17, in which heating means 13 can be provided. A first line 21 runs from the water tank 17 to the mixing unit 5. Furthermore, a second line 22 extends from the tank 17 into the settling tank 6 with a series (two in the example shown) disposed near the underside 9 of said settling tank 6 nozzles 24. Suitable pumping means 25 and control valves 27 are provided between the tank 17 and said conduits 21, 30, for pumping around and controlling a specific water flow to the mixing unit 5 and the settling tank 6. The whole is placed on a mobile undercarriage 35, so that the device 1 can be set up on a beach, or at least near the place where the contaminated sand is located. This allows 5 large logistics flows (transport of sand to be cleaned and cleaned) to be avoided. The undercarriage 35 is herein preferably provided with adjustment center (mechanical, hydraulic or pneumatic), so that the device can always be leveled, which is desirable for proper operation, irrespective of any irregularities in the intended arrangement position.

With the coarse dirt filter 2, coarse particles such as wreck, stones and / or bottles 4 can be filtered from the sand-oil mixture 10 before this mixture 10 is supplied to the mixing unit 5. To this end, the coarse dirt filter 2 can be designed, for example, as a series of rotating rollers arranged next to each other, embodied in Fig. 1 with a substantially star-shaped cross-section, wherein the supporting surface of the rollers can possibly include a slight angle of inclination with the horizontal plane. (not shown). The distance between consecutive rollers determines what is and is not passed to the lower conveyor 3. Waste that has not been passed through is discharged by the rotating rollers in the direction of arrow A. Alternatively, the coarse dirt filter 2 can for instance be designed as one of conveyor belt provided with openings, wherein the size of the openings are chosen such that said coarse parts 4 are not passed through and are discharged via the belt in the direction of arrow A, while the rest of the mixture 10 is passed to the lower conveyor 3 .

The conveyor 3 can be designed, for example, as a driven endless conveyor belt, a bucket ladder or as a screw conveyor, as in the case shown, and is preferably provided with second filtering means 7 near its end above the mixing unit 5, which in the example shown are designed as a grid with bars diverging from one another with respect to H. As a result, the distance between the bars becomes larger as the transport progresses, whereby in the first instance only relatively small parts are passed through the mixing unit 5, and near the end of the conveyor 3 also larger parts, such as stones, are passed. However, the latter do not end up in the mixing unit 5, but in third filter means 11, located between the mixing unit 5 and the settling tank 6, as indicated by arrow T. This prevents potentially harmful, relatively large parts from ending up in the H mixing unit 5.

In the exemplary embodiment I shown, the mixing unit 5 comprises three mixers 26, viewed one behind the other in the direction of transport, in particular screw mixers, each of which is at least partially surrounded by a tube 27 and which is a sand-oil mixture guided by the mixing unit 5 10 cutting or grinding and mixing in successive steps between the edges of the screws 26 and the inner wall of said tube 27. It will be clear that the mixing unit 5 can comprise more or fewer mixers than the one shown in FIG. three. Moreover, these mixers 26 do not necessarily have to be arranged one behind the other, but can, for example, also be arranged side by side, each mixer 26 homogenizing a part of the sand-oil mixture 10 and the mixers then alternately deliver these homogenized portions to the settling tank 6 . In addition, many other types of mixers can be used. During mixing, water can be added from tank 17 via the first line 21, the pump means 25 and the control valve 27, in order to dilute the mixture.

In the exemplary embodiment shown, the input means 11, via which mixture 10 homogenized in the mixing unit 5 is supplied to the settling tank 6, comprise a trough which is provided with holes increasing in size. The smaller holes are herein located above the settling tray 6 and the larger holes open onto a drain (not shown) disposed next to 9, so that these input means 11 function as third filter means, with which relatively large parts can be excluded from the settling tray 6. The second and third filtering means 7, 11 can of course be designed in many other ways.

The settling tank 6 is, as stated, substantially funnel-shaped, and provided with a first winding means 23, designed as a substantially rod-shaped hollow or solid body, which is arranged centrally in the settling tank 6, and can be rotated with the aid of suitable drive means 28 is about a substantially vertical axis, as indicated by arrow P. With this first agitating means 23, circulating currents can be generated in the settling tank 6, which promote the separation process in the tank 6 and contaminants already separated, floating on or near the water surface ( in the present exemplary embodiment oil) to the second discharge means 14. These second discharge means 14 can for instance be designed as a drain and / or overflow gutter, which extends along at least a part of the peripheral edge of the settling tank 6. The first head body 23 preferably has a somewhat angular, for example diamond-shaped or polygonal cross-section. The angular shape gives rise to turbulent eddy currents 20 during rotation of the body 23, which can further improve the separation process in the bin 6. Of course, more than one first stirring body 23 can be arranged in the settling tank 6, which moreover can all have a different cross-section.

The previously described nozzles 24, near the underside 9 of the settling tank 6 form second turbulence means 24, with which rising eddy currents can be generated by spraying water into the settling tank 6 via these nozzles 24, in substantially upward direction. These streams will also benefit the separation process, because they prevent small oil particles from being dragged down by the sinking sand.

In the exemplary embodiment shown, the first discharge means 12 comprises air lift means for removing sand deposited therein from the settling tank 6. These air-lifting means comprise a discharge pipe or hose 30 connected to the underside 9 of the settling tank 6, into which blowing means 32 open a short distance from the settling tank 6, with which compressed air can be blown into the pipe or hose 30, in a substantially radial direction. As a result, a vacuum is created in the pipe or hose part 30 extending between the settling tank 6 and the blown-in air, whereby sand is sucked out of the tank 6 and is transported upwards, in the direction of arrow C. With the air lifting means described above Sand can be discharged from device 1 with minimal energy and in a controlled manner.

The device 1 furthermore preferably comprises measuring and control means (not shown) which are known per se for, for example, the rotation speed of the first tossing means 23 and the flow rate introduced into the settling tank 6 through the nozzles of the second tossing means 24. and thereby influence the intensity of the eddy currents generated and ultimately the separation process in the bin 6.

The device 1 further comprises heating means 13 for keeping the water circulating in the device 1 at a desired temperature, for example between 40 ° and 60 °. As a result, the viscosity of the oil I is increased and, according to the applicant's tests, the separation process can be further improved. In the exemplary embodiment shown, the heating means 13 are arranged in the water tank 17. In addition or instead thereof, heating means may also be provided in the settling tank 6 and / or the mixing unit 5.

The operation of the device 1 is as follows. With a shovel (not shown), a layer of sand contaminated with oil, for example, is taken from the beach. One shovel load can for instance weigh about two I 30 tons. This load is poured above the conveyor 3, indicated by arrow S, 11 ♦ above the coarse dirt filter 2. This will hold and remove the coarse dirt 4, such as stones and bottles, and pass the remaining sand-oil mixture 10 to the underlying conveyor. 3. Via this conveyor 3, the mixture 10 is then directed towards the mixing unit 5, via second filtering means 7. In the mixing unit 5, the mixture 10 in the three consecutive screw mixers 26 is mixed into a substantially homogeneous mixture. Heated water is preferably added from tank 17, so that a relatively liquid sand-water-oil mixture I is obtained. This is then supplied in a continuous flow to the settling tank 6, via the third filter means 11. As soon as the mixture 10 is in the settling tank 6, separation occurs under the influence of gravity. The heavier sand and possibly pebbles and smaller stones present in the mixture thereby sink downwards under the influence of gravity, where they are continuously discharged from the settling tank 6 via the first discharge means 12. This discharged sand is preferably returned to the place where it came from, but can for example also be collected in a storage reservoir 34 to be used, for example, as filler sand in noise barriers or under asphalt roads.

The relatively light impurities (in this case oil) will collect near or on the water surface by being driven by the rotating movement of the first toiling means 23 to the second discharge means 14, to flow via them from the container 6, possibly together with a amount of water, to the collecting reservoir 15. There, the oil layer is driven from the water by means of the skimmer 18 and, for example, stored in a reservoir 36 for further processing. The water collected in the collecting reservoir I 15 can be reintroduced via the return line 16 and the pump means 25 H and control valves 27 into the device 1, in particular the settling tank ff and / or the mixing unit 5, optionally after being brought up to temperature. by the heating means 13.

The separation process can be influenced, for example, be accelerated or delayed, for example by shortening or extending the average residence time of the mixture 10 in the settling tank 6, for example by varying the flow of the input and output flows and / or the height of the settling tank 6. The separation process can be further influenced by, inter alia, the adjustment of the water temperature and by controlling the first and / or the second winding means 23, 24, in order to control the eddy currents generated in the settling tank 6, in particular the intensity thereof to influence.

This figure description is based on a device 1 for cleaning sand contaminated with oil. However, the device can also be used advantageously to clean sand mixed with seaweed or algae. In that case, the homogenization of the sand-seaweed mixture and the heating of the water in the settling tank can be omitted.

It should be noted that combinations of parts of the exemplary embodiment shown are expressly considered to also fall under the inventive concept. Moreover, many variations are possible within the scope of the invention as set forth in the claims.

The first delivery means can for instance comprise any other transport means in addition to or instead of the air lift means, for removing settled sand from the settling tank, for instance a screw conveyor, a disk conveyor or a conveyor belt. The second discharge means can for instance be designed as an overflow gutter extending along at least a part of the upper edge of the settling tank. The mixing unit may consist of side-by-side mixers, which in turn deliver an amount of mixture to the settling tank. In addition, the mixers can take many different embodiments. The invention is therefore by no means limited to the screw mixers shown. The settling tank may have a different shape, but is preferably slightly tapered near the underside in order to guide the sand towards the first discharge means. The first and second winding means may be designed differently, for example as jacks, or be omitted entirely.

These and many variations are understood to fall within the scope of the invention as set forth in the following claims.

Claims (21)

Method according to claim 1, wherein the removed sand layer with the contaminants present therein is mixed into a substantially homogeneous mixture, prior to feeding to the settling tank 15 (6). 3. Method as claimed in claim 2, wherein water is added to the mixture during the mixing, such that a relatively liquid mixture is obtained. 4. A method according to any one of the preceding claims, wherein the water used in the method is heated to a temperature between approximately 30 ° and 80 ° Celsius, more in particular between approximately 35 ° and 60 ° Celsius and preferably approximately 40 ° Celsius. 5. Method as claimed in any of the foregoing claims, wherein the water in the settling tank (6) is set in motion such that at least a part of the water surface is free from impurities floating on this water surface, wherein the contaminated sand mixture via this at least one free surface portion is continuously supplied to the settling tank (6). 6. Method according to one of the preceding claims, wherein impurities floating on and near the water surface, optionally together with a part of the water, are continuously discharged from the settling tank (6) by means of an overflow gutter (14). 7. Method as claimed in any of the foregoing claims, wherein coarse dirt, such as wreck wood, cans and bottles, is filtered from the contaminated sand mixture, before the mixture is further mixed or supplied to the settling tank (6). A method according to any one of the preceding claims, wherein circulating, substantially horizontal eddy currents and / or upward, substantially vertical eddy currents are generated in the settling tank. 9. Method as claimed in any of the foregoing claims, wherein water for the method is taken from a water mass adjacent to the beach to be cleaned. The method according to any of the preceding claims, wherein the water used is recycled. 11. Method for cleaning beaches, of impurities left behind or washed in, wherein an upper layer of sand with impurities thereon and / or impurities contained therein is taken up, then mixed into a homogeneous mixture, preferably diluted with heated water , after which the mixture is introduced into a continuous flow into a settling tank (6) filled with preferably heated water, the sand sinking under the influence of gravity and first discharge means arranged near a bottom of the settling tank (6) (12) is continuously discharged from the settling tank (6) and returned to the beach, and the contaminants continue to float in or near the water surface and are continuously discharged from the settling tank (6) by means of second discharge means (14) to a collection reservoir for further processing, for example incineration. 12. Device for cleaning contaminants such as oil or algae or (sea) whose contaminated sand, comprising a mixing unit (5), for mixing the sand and the contaminants into a substantially homogeneous mixture, a sediment basin filled with water (6), feed means (11) emerging therefrom for feeding mixture coming from the mixing unit (5), first and second discharge means (12, 14) for discharging sand settled substantially continuously from the settling tank (6) during use, impurities, respectively, floating on the water, wherein heating means are furthermore provided for heating the water in the settling tank (6) and water added to the mixture optionally in the mixing unit (5). 13. Device as claimed in claim 12, wherein the mixing unit (5) comprises at least one and preferably a series of spiral mixers (26) surrounded by tube parts (27), preferably screw mixers (26) with a hollow core, which mixers ( 26) can, in mutual cooperation, continuously supply a substantially homogeneous mixture to the settling tank (6). Device as claimed in claim 12 or 13, wherein first settling means (23) are provided in the settling tank for generating circulating eddy currents, around a substantially vertical axis. 15. Device as claimed in claim 14, wherein the first toiling means (23) comprise a centrally arranged, substantially rod-shaped or tubular body 25, rotatable about a substantially vertical axis, with an angular, preferably diamond-shaped cross-section. Device as claimed in any of the claims 12-15, wherein second settling means (24) are provided in the settling tank (6) for generating ascending, substantially vertical eddy currents. Device as claimed in any of the claims 12-16, wherein the second toiling means (24) comprise at least one and preferably a series of nozzles arranged near the bottom of the settling tank (6), for introducing water into the settling tank (6) in an upward direction. The device of any one of claims 12-17, wherein the device (1) further comprises a coarse dirt filter. 19. Device as claimed in any of the claims 12-18, wherein the first discharge means (12) comprise air-lifting means, provided with a discharge tube connected to a settling tank (6) near a bottom side, blowing means for placing in the tube, at some distance from the settling tank (6) blows compressed air in a substantially radial direction, so that underpressure is created in the pipe section between the settling tank (6) and the blown in air and sand is sucked in from the settling tank (6) 20. Device as claimed in any of the claims 12-19, wherein the device is of mobile design, for displacement along a beach, at least contaminated area. 21. Device as claimed in any of the claims 12-20, wherein the supply and discharge capacity of the supply means and the first and second discharge means, as well as the size of the settling tank (6) is dimensioned such that at least about 1 tonne of contaminated sand can be processed, in particular more than 3 tons and preferably about 5 tons or more. 1 HOO i