NL2002873C2 - Device and method for inhibiting growth of organisms on a submerged object and a ship provided with such device. - Google Patents
Device and method for inhibiting growth of organisms on a submerged object and a ship provided with such device. Download PDFInfo
- Publication number
- NL2002873C2 NL2002873C2 NL2002873A NL2002873A NL2002873C2 NL 2002873 C2 NL2002873 C2 NL 2002873C2 NL 2002873 A NL2002873 A NL 2002873A NL 2002873 A NL2002873 A NL 2002873A NL 2002873 C2 NL2002873 C2 NL 2002873C2
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- Prior art keywords
- electrodes
- state
- electrode
- copper
- organisms
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Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B63—SHIPS OR OTHER WATERBORNE VESSELS; RELATED EQUIPMENT
- B63B—SHIPS OR OTHER WATERBORNE VESSELS; EQUIPMENT FOR SHIPPING
- B63B59/00—Hull protection specially adapted for vessels; Cleaning devices specially adapted for vessels
- B63B59/04—Preventing hull fouling
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- Chemical & Material Sciences (AREA)
- Engineering & Computer Science (AREA)
- Combustion & Propulsion (AREA)
- Mechanical Engineering (AREA)
- Ocean & Marine Engineering (AREA)
- Water Treatment By Electricity Or Magnetism (AREA)
Description
Device and method for inhibiting growth of organisms on a submerged object and a ship provided with such device 5 The present invention relates to a device for inhibiting growth of organisms, like micro-organisms, algal and crustaceans, on a surface of an object that is at least partially submerged in a fluid. More specific, the device uses an electrolytic process to inhibit the growth. For 10 example, the device can be used for ships that are at least partially submerged in water. The growth of organisms, also including the adhesion of organisms to the object, is also referred to as fouling.
Existing growth inhibiting means use an anti-15 fouling paint, comprising toxic pigments, such as cuprous oxide and/or mercury compounds. The use of such paints may result in environmental pollution and for this reason the use of such paints is often not permitted.
In another existing growth inhibiting device use 20 is made of a current system using metal electrodes. In this system the ships hull serves as a cathode in an electrolytic process. As an alternative also a device using an independent cathode can be used. In this system significant amounts of copper oxides are present in the water 25 surrounding the ship. In addition, this device requires a supply of energy thereby requiring additional energy sources, like batteries.
The object of the present invention is to improve the growth inhibiting or anti-fouling of organisms on an 30 object that is at least partially submerged in a fluid, like water .
This object is achieved with the device according to the present invention, wherein the device comprises: 2 - a power source for supplying an electric and/or electromagnetic field; - a first electrode, or first configuration of electrodes, that in use is connected to the power 5 source; - a second electrode, or second configuration of electrodes, that in use is connected to the power source; and - switching means for supplying a current and/or 10 voltage through or to the first and second electrodes, wherein in use the switching means switch the first and second electrodes between a first and second state, wherein in at least the first state, with at least one of the electrodes comprising 15 copper, the electrolytic process dissolves copper ions in the fluid.
By providing two electrodes, or two configurations of electrodes with more than one electrode in each configuration, and a power source the device is capable in 20 providing a voltage or current to an electric circuit. By supplying power to the electrodes, with at least one of the electrodes comprising copper, copper ions enter the fluid surrounding the object that requires protection. Especially copper is effectively used for the electrodes since under 25 most conditions it corrodes and provides the necessary cuprous ions. It has been established that cuprous oxides have a strong toxic action on growth of organisms, such as algae, shellfish, and barnacles. Dissolved copper originating from the electrodes oxidises into copper oxides 30 that are insoluble. The fluid, for example fresh water or sea water, acts as an electrolyte containing the free ions and the fluid behaves as an electrically conductive medium. Due to the toxic effects, fouling growth will be prevented 3 or at least significantly inhibited on the object that is submerged in the fluid.
As an indication only, an inhibiting effect is realised in case leaching rates of copper oxide exceeds 10 5 microgram/cm2 per day meaning that aim2 surface can be protected by leaching about 30 grams of copper oxide per year. In case of a water intake of 600 m3/hour about 80 kg of copper per year will be required to protect such water inlet.
10 In the device according to the present invention switching means are provided for switching between at least a first and second state. In at least the first state the first electrode is provided with current. The electric circuit is closed via the electrolyte surrounding the object 15 to the other electrode. This results in a continuous development of (cuprous) oxide by electrolytic dissolution of copper.
In an advantageous embodiment according to the present invention, in another state no power is supplied to 20 the electrodes. By periodically switching between the first and this state of the device a pulsating effect on growth inhibition is achieved. By alternately having a first state in which power is supplied and another state in which no power is consumed the overall energy consumption of the 25 device according to the present invention is decreased. In addition, this embodiment limits the use of external power supplies, like batteries. Furthermore, by switching between the states a type of shock effect against growth is achieved. It has been established that the pulsating effect 30 realised by periodically dissolving copper from at least one of the electrodes further enhances growth inhibition as compared to a continuous supply of copper.
4
The system according to the invention is in a preferred embodiment applied to a ship. However, the system according to the invention is also applicable to other systems, like inlet channels of a cooling water system in 5 the process industry and/or power plant.
In an alternative advantageous embodiment according to the present invention the electrodes in the first and another state are provided of an opposite polarity. By having an alternating supply of current, the 10 wear of the electrodes is divided over at least the first and second electrodes. This approximately doubles the life span of the electrodes. This results in an efficient operation of the device according to the present invention as maintenance is limited. In addition, cost of replacing 15 electrodes is also minimised.
The device according to the present invention can be integrated in the object to be protected. This renders the location of the object less important as the device is part of the object. Alternatively, the device is an 20 independent device that is used in a harbour or around a water intake, for example. In such an embodiment the device acts as a stand-alone device protecting an area in which objects can be located.
In a preferred embodiment according to the present 25 invention the electrodes are embedded in the object.
By embedding the electrodes in the object to prevent protruding parts the device is less sensitive to damage. Such damage may occur in case the object comes into contact with another object. In case of the object being a 30 ship this may involve accidents with other ships or contact with a landing stage. In a preferred embodiment the electrodes are embedded in the skin surface of the object.
In an alternative embodiment one or more of the electrodes 5 are provided in the interior of the object, provided there is contact possible between the embedded electrodes and the electrolyte. Such alternative embodiment may be applied to so-called Impressed Current Anti-Fouling (ICAF) systems, 5 and/or to Impressed Current Cathodic Protection (ICCP) systems .
In a preferred embodiment according to the present invention the electrodes are electrically insulated from the object.
10 By electrically insulating the electrodes from the object the electric field around the object is increased.
The fluid behaves as an electrolyte and protects the surface of the object that is submerged into this fluid.
In a further preferred embodiment according to the 15 present invention the switching means switch the electrodes between the first, second and a third state wherein in one of these states no power is supplied to the electrodes.
By defining three different states a combined effect of shock therapy and the use of opposite polarities 20 can be achieved. Surprisingly, an increased effect on the growth inhibition is achieved. In a preferred embodiment according to the present invention the first state represents a situation in which the electrodes have a first polarity. The second state represents a situation in which 25 these electrodes are provided with the opposite polarity, i.e. the negative electrode becomes the positive electrode and vice versa. The third state represents the situation in which no power is supplied to the circuit. The switching means can switch between the different states in different 30 order. A straight forward sequence would be from the first to the second to the third and back to the first state. Another sequence is switching from the first to the third to the second to the third and back to the first state. In this 6 alternative sequence the energy usage of the device is further decreased. Of course other sequences would be possible .
In a preferred embodiment according to the present 5 invention the switching means periodically switch to the third state every 0-1000 seconds. Preferably, this third state is kept during a time interval in the range of 0-1000 seconds. The intervals that are actually used depend on the circumstances, for example including the type of fluid 10 (fresh water or sea water), the temperature of the fluid, the type of object (material, shape etc.) and of course the organisms that are present.
In a further preferred embodiment according to the present invention at least one of the electrodes comprises 15 electrolytic copper.
Electrolytic copper is electrolytically produced and has a copper content of about 99.9%, and preferably 99.95%. Electrolytic copper is highly conductive. This increases the efficiency of the electrodes and, therefore, 20 of the entire device.
In a further preferred embodiment according to the present invention an additional electrode is provided.
Depending on the object to be protected, e.g. the shape and/or size thereof, the use of additional electrodes 25 increases the effect of the device and improves the protection of the object. For example, an additional electrode of copper can be provided to improve the overall efficiency. Alternatively or additionally, an aluminium electrode can be used to limit the impact of the device on 30 the environment. In case an aluminium electrode is used in addition to the copper electrodes aluminium oxides are provided to the fluid. These aluminium oxides enclose the copper oxides thereby minimising the environmental impact.
7
Preferably, this additional electrode is part of an additional electric circuit. The use of a separate circuit results in a more independent operation. Furthermore, alternatively or additionally, the additional electrode can 5 be used for cathodic protection in case a part of the object submerged in the fluid is of metal. This stops or at least minimises the corrosion process.
In a further preferred embodiment according to the present invention indicating means are provided to detect a 10 required change of an electrode.
Providing indicating means achieves an efficient device as an efficient operation is guaranteed by indicating a required change of one or more of the electrodes in case too much material of the electrode has been dissolved. For 15 example, the indicating means can be provides as detection means for a leakage in a space or room inside a cofferdam or ship's hull.
The present invention also relates to a ship and/or inlet channel provided with a device as described 20 above.
Such ship or inlet channel provides the same effects and advantages as those stated with reference to the device.
The present invention further also relates to a 25 method for inhibiting growth of organisms, like microorganisms, algal and crustacean, on a surface of an object that is at least partially submerged in a fluid, comprising the steps of: - providing a device as described above; and 30 - activating the device.
Such method provides the same effect and advantages as those stated with reference to the device and ship.
8
Further advantages, features and details of the invention are elucidated on the basis of preferred embodiments thereof, wherein reference is made to the accompanying drawings wherein: 5 - figure 1 shows a schematic overview of the device according to the invention when applied to a ship; - figure 2 shows a schematic overview of the device according to the invention when applied to a water inlet; 10 - figure 3 illustrates the electric circuit according to an embodiment of the invention; and - figure 4 illustrates an embedded electrode of the device according to an embodiment of the invention.
15 A ship 2 (figure 1) is partly submerged in water.
The part below water line 4 is in contact with water 6 in the direct surroundings of ship 2. Ship 2 is provided with a device according to the present invention comprising an electric circuit 8. In the illustrated embodiment electric 20 circuit 8 comprises a first electrode 10 and a second electrode 12. As an example, a ship 2 with a length of about 100 meters is provided with four cupper electrodes on each side of ship 2. Other configurations are also possible.
In an alternative application of the device 25 according to the present invention, inlet pipe 32 (figure 2) is provided with the similar device involving a similar electric circuit 8 as shown in figure 1. Again there are two electrodes 10, 12 in a circuit 8 with water 6 surrounding the inlet 32. In the illustrated embodiment water inlet 32 30 is an inlet of a ship. Also, inlet 32 can be another water inlet, for example for a building.
The circuit 8 with electrodes 10, 12 (figures 3 A, B and C) can be provided with current from current source 9 14. Switches 16, 18 switch the device between the different states. In a first state (figure 3A) switch 16 connects current source 14 with electrode 10 via circuit line 20. In this first state switch 18 connects source 14 with electrode 5 12 via circuit line 22. In the second state (figure 3B) switch 16 connects the source 14 with electrode 10 via circuit line 24. In this second state, switch 18 connects source 14 with electrode 12 via circuit line 26. In the third state (figure 3C) switch 16 is in an open state with 10 connection 28. In this third state switch 18 is in an open state with the open connection 30. Water 6 in the direct surroundings of ship 2 acts as electrolyte for the device.
In a possible configuration an electrode 32 (figure 4) is provided in a ships hull 34. In hull 34 is 15 provided an insert 36. In the illustrated embodiment insert 36 is provided with a diameter of about 30 mm. In the illustrated embodiment insert 36 comprises a plastic putti 38, and a non-conductive Teflon, neoprene or polyethylene cover 40 provided with slits, grooves and/or slots or slot 20 holes for covering the filling 44 of a metal like copper or aluminium. The slots etc. enable sufficient transport of cupper ions. In the illustrated embodiment cover 40 is for more than 60% provided with such slots enabling sufficient transport. Between cover 40 and filling 44 a space can be 25 provided to allow sea water to contact filling 44. Cover 40 prevents holes in hull 34 in case the cupper of electrode surface 42, made of electrolytic cupper, is dissolved. For electric insulation insulating element 46 of plastic reinforced glassfiber is provided in element 50. To prevent 30 leakage a rubber gasket (not shown) can be provided between filling 44 and the horizontal surface area of element 46. Teflon bush 48 is provided in an opening in element 50 for preventing damage to gaskets and/or insulating elements when 10 mounting nut 54, for example. Plastic putti 38, element 46 and optionally bush 48 can be formed from one piece of (electrically) insulating material. Washer 52 is provided between nut 54 and element 50. Cable 56 connects electrode 5 32 with the other parts of the device according to the invention. In the illustrated embodiment cable 56 is covered with a bronze (or any other appropriate material) cover 58 that is part of a detection system to detect leakage in case the cupper is dissolved. Cover 58 is provided with a rubber 10 O-ring 60 and is connected to connecting part 62 of element 50 by bolt 64. In an alternative embodiment connecting part 62 and element 50 are provided in one-piece. Stuffing tube 66 feeds cable 68 through cover 58.
To provide an indication that an electrode 15 requires replacement an electrical contact is optionally provided in cavity 74 of insert 36. The contact is activated in case water contacts the electrical contact. This indicates that replacement of the electrode is required. For the purpose of detection in the illustrated embodiment a 20 small channel 70 with a diameter of about 2 mm is provided in the M16 screw stud 72. Optionally, as part of the leakage detection system a gauge-glass or inspection-glass is integrated in bronze cover 58 to enable visual inspection.
In situations wherein an object is at least 25 partially submerged in a fluid like fresh water or sea water a growth inhibiting effect can be achieved by providing a device according to the present invention. In case the object is submerged in the fluid, the device is activated to protect the object as an anti-fouling measure. The device is 30 switched between at least two different states. This results in a shock effect and/or in limited energy consumption with limited wear of the electrode. Also, these effects can be combined using three different states.
11
Experiments have shown that an effective amount of cupper of about 35 kg. (e.g. diameter of about 200 mm. and height of about 125 mm.) enables protection of about 5 years with the device according to the invention activated 50% of 5 the time at 1 A (DC).
The present invention is by no means limited to the above described embodiments thereof. The rights sought are defined by the following claims, within the scope of which many modifications can be envisaged.
12
CLAUSES
1. Device for inhibiting the growth of organisms, like 5 micro-organisms, algal and crustacean on a surface of an object that is at least partially submerged in a fluid using an electrolytic process, the device comprising: - a power source for supplying an electric and/or 10 electromagnetic field; - a first electrode, or first configuration of electrodes, that in use is connected to the power source; - a second electrode, or second configuration of 15 electrodes, that in use is connected to the power source; and - switching means for supplying a current and/or voltage through or to the first and second electrodes, wherein in use the switching means 20 switch the first and second electrodes between a first and a second state, wherein in at least the first state, with at least one of the electrodes comprising copper, the electrolytic process dissolves copper ions in the fluid.
25 2. Device according to clause 1, wherein the electrodes in the first and second state are provided with an opposite polarity.
30 3. Device according to clauses 1 or 2, wherein the electrodes are embedded in the object.
13 4. Device according to clauses 1, 2 or 3, wherein the electrodes are electrically insulated from the object.
5. Device according to one or more of the clauses 1-4, 5 wherein the switching means switch the electrodes between the first, the second and a third state wherein in at least one state no current and/or voltage is supplied to the electrodes.
10 6. Device according to clause 5, wherein the switching means periodically switch to the third state with an interval in the range of 0-1000 seconds.
7. Device according to clause 5 or 6, wherein the third 15 state is maintained during a time period in the range of 0-1000 seconds.
8. Device according to one or more of the clauses 1-7, wherein at least one of the electrodes comprises 20 electrolytic copper.
9. Device according to one or more of the clauses 1-8, wherein an additional electrode is provided.
25 10. Device according to clause 9, wherein the additional electrode is part of an additional electrical circuit.
11. Device according to one or more of the clauses 1-10, further comprising indicator means for indicating a 30 required change of the electrode.
12. Inlet channel provided with a device according to one or more of the clauses 1-11.
14 13. Ship provided with an inlet channel according to clause 12 and/or a device according to one or more of the clauses 1-11.
5 14. Method for inhibiting the growth of organisms, like micro-organisms, algal and crustaceans, on a surface of an object that is at least partially submerged in a fluid, comprising the steps of: - providing a device according to one or more of the 10 clauses 1-11; and -activating the device.
Claims (14)
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL2002873A NL2002873C2 (en) | 2009-05-12 | 2009-05-12 | Device and method for inhibiting growth of organisms on a submerged object and a ship provided with such device. |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| NL2002873A NL2002873C2 (en) | 2009-05-12 | 2009-05-12 | Device and method for inhibiting growth of organisms on a submerged object and a ship provided with such device. |
| NL2002873 | 2009-05-12 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| NL2002873C2 true NL2002873C2 (en) | 2010-11-15 |
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Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| NL2002873A NL2002873C2 (en) | 2009-05-12 | 2009-05-12 | Device and method for inhibiting growth of organisms on a submerged object and a ship provided with such device. |
Country Status (1)
| Country | Link |
|---|---|
| NL (1) | NL2002873C2 (en) |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3766032A (en) * | 1971-07-19 | 1973-10-16 | A Yeiser | Method for control of marine fouling |
| JPS5737091A (en) * | 1980-08-14 | 1982-03-01 | Mitsubishi Heavy Ind Ltd | Adhesion-proofing process of ship |
| WO1987003261A1 (en) * | 1985-11-29 | 1987-06-04 | The University Of Sheffield | Marine biofouling reduction |
| EP0562442A2 (en) * | 1992-03-24 | 1993-09-29 | Ngk Insulators, Ltd. | Method for making organism deposit-inhibiting pipe |
| EP1084947A1 (en) * | 1999-09-17 | 2001-03-21 | Magnus Kvant | A method of durably and lastingly protect a surface in contact with water from biological fouling |
-
2009
- 2009-05-12 NL NL2002873A patent/NL2002873C2/en not_active IP Right Cessation
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US3766032A (en) * | 1971-07-19 | 1973-10-16 | A Yeiser | Method for control of marine fouling |
| JPS5737091A (en) * | 1980-08-14 | 1982-03-01 | Mitsubishi Heavy Ind Ltd | Adhesion-proofing process of ship |
| WO1987003261A1 (en) * | 1985-11-29 | 1987-06-04 | The University Of Sheffield | Marine biofouling reduction |
| EP0562442A2 (en) * | 1992-03-24 | 1993-09-29 | Ngk Insulators, Ltd. | Method for making organism deposit-inhibiting pipe |
| EP1084947A1 (en) * | 1999-09-17 | 2001-03-21 | Magnus Kvant | A method of durably and lastingly protect a surface in contact with water from biological fouling |
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| V1 | Lapsed because of non-payment of the annual fee |
Effective date: 20121201 |