Technical field

The present invention relates to a method and a device for the cleaning and disinfection of the outside hull of a vessel. In particular the present invention is of relevance for the cleaning and disinfection of vessels that form part of or are servicing fish farming facilities.

Background of the invention

Fish farming facilities are generally serviced by ships. Ships will deliver the feed for the fish and ships also transport the fish from the farm facility to the slaughter facility.

The fish farming industry applies strict standards to maintain bio security, in order to prevent contamination from one sea-sector to another sea-sector or one fish farming facility to another. One threat in this connection is the ships sailing between the facilities or sea-sectors. The sea-sectors are predefined sectors of the ocean often defined by the industry or the authorities, and specific requirements are defined for moving equipment from one sea-sector to another.

Today, when a ship has been at a facility with fish illness or is travelling from a facility or area with illness status to a facility or area without illness, or when moving from one sea-sector to another, the ship may have to be taken to the slipway/boat yard where it is washed down and disinfected.

This is an expensive and time-consuming procedure. Often the ship will have to wait in order to get access to the local slipway/boat yard. For this reason, the ship will often be out of traffic for a number of days. The placing of the ship on slipway/boat yard will entail expenses in the same manner as the washing down and disinfection itself. In addition, the loss in freight earnings may be considerable. Disinfection at a slipway often involves cleaning the outside of the hull with a disinfection agent. This is in great part often a manual operation strongly dependent on human labor. Thus, it is also fault prone. It is difficult to get a qualified measurement of adequate cleaning of the outside of the hull. Another drawback with this procedure is also that the disinfection process often depends on poisonous disinfection agents that may leak into the environment and cause damage. The same problems arise when fish farm facilities and its installations and components are contaminated. Today, the equipment has to be disassembled and brought to facilities configured for cleaning and disinfection of such equipment in order to exterminate the contamination. This process may be performed periodically when the fish are slaughtered.

This is an expensive and time-consuming task, and often complicated and hazardous.

Using ozone for prevention of marine growth on boat hull is described in US 4092943 A. The publication describes an underwater marine protection system for preventing or retarding marine growth on vessels while the marine vessel is anchored in the boat slip.

Another invention with a solution for the prevention of marine growth is published in WO 98/28184 Al, where a hull designed cover in the pleasure craft mooring shall treat the hull with the aim to avoid the necessity to treat the hull with protective coating, i.e. protective paint.

Generating ozone is well known to a skilled person, and WO 2008/146940 Al defines multiple ways to generate ozone.

It is the object of the present invention to provide a solution to the problem of cleaning and disinfection of vessels that overcomes some or all of the above-described drawbacks.

Summary of the present invention

The abovementioned object is achieved by the methods according to independent claims 1 and 6, and devices according to independent claims 10 and 16. Other advantageous embodiments and features are set out in the dependent claims.

Brief description of the Drawings

Figure 1 describes the device seen from the front of a vessel.

Figure 2 describes the device seen from the side of a vessel.

Figure 2A describes the device in the form of a floating dock seen from above.

Figure 2B shows a profile cross section of the device in the form of a floating dock and the vessel's hull with the equipment for producing/mixing the disinfection agent on board the vessel.

Figure 2C describes the device seen from the side of a vessel. Figure 3 shows a profile cross section of the device and the vessel's hull.

Figure 4 shows a profile cross section of the device and the vessel's hull including an extension sheet applied from the top of the part of the hull not submerged in water extending down and overlapping the device.

Figure 5 describes the electrolysis installation incorporated in the device.

Figure 6 shows how the electrodes are connected to an electrical charge (DC

accumulator).

Figure 7 shows how the electrodes can be incorporated in the device and the weight section at the bottom part of the device.

Figure 8 shows the device mounted on a net cage.

Figure 9 shows a profile cross section of the device and a buoy.

Detailed description of the invention/preferred embodiments

According to the present invention there are several possible solutions for how to diffuse disinfection agents over the outside of the hull 2 of a vessel or installation or part of installation partly submerged in water, hereafter denoted as vessel partly submerged in water, that is to be treated. The treatment including, with reference to Figures 1 to 4, transporting disinfection agents to pipes or hoses 5 that are located close to the bottom 8 of the vessel's hull 2, and diffused evenly along whole or parts of the length of the vessel 1.

According to one possible embodiment of the present invention as described in figure 1 and figure 2, a sheet 3 covers the whole or parts of the outside part of the hull 2 that is submerged in water 20. The sheet 3 may have incorporated spacers 6 at regular intervals in order to keep the space defined between the sheet 3 and the outside of the hull 2 that is submerged in water at a minimum distance. Other mechanisms, such as tubes, knots, filled chambers or channels or other, can be adapted to achieve the minimum distance between the sheet and the vessels outside hull at any given place. In the bottom of the sheet, weight elements 4 may be incorporated to keep the sheet 3 in position both during mounting and during the treatment of the hull. Diffuser hoses 5 are

incorporated/mounted in the sheet 3 or located in the space between the sheet and the boat hull in order to distribute the disinfection agent in to the space defined by the sheet 3 and the hull 2. Floating elements 7 are mounted on the sheet 3 in order to enable the sheet to extend all the way up to the surface of the water 20 and to prevent water from outside 20 of the sheet to mix with the water inside of the sheet. The floating elements 7 are capable of supporting a raised surface level 17 of the inside of the sheet 3 relative to the surface of the water 20 on the outside of the sheet 3.

According to another possible embodiment of the present invention as described in figure 2A, figure 2B and figure 2C a sheet 3 covers the whole or parts of the outside part of the hull 2 that is submerged in water 20. The sheet 3 may have incorporated spacers 6 as seen in figure 1 at regular intervals in order to keep the space defined between the sheet 3 and the outside of the hull 2 that is submerged in water at a minimum distance. Other mechanisms, such as tubes, knots, filled chambers or channels or other, can be adapted to achieve the minimum distance between the sheet and the vessels outside hull at any given place. At the bottom of the sheet, weight elements 4 may be incorporated to keep the sheet 3 in position both during mounting and during the treatment of the hull. Diffuser hoses 5 are incorporated/mounted in the sheet 3 or located in the space between the sheet and the boat hull in order to distribute the disinfection agent in to the space defined by the sheet 3 and the hull 2. Floating elements 18, 22 are assembled together to form a frame or a floating dock to which the sheet 3 is fixed, and to enable the sheet to extend all the way up to the surface of the water 20 and to prevent water from outside 20 of the sheet to mix with the water inside of the sheet. The floating elements 18, 22 are capable of supporting a raised surface level of the inside of the sheet 3 relative to the surface of the water 20 on the outside of the sheet 3. The floating elements 7, 18, 22 may include the function of winding / tightening 27 the sheet and thereby decreasing the space confined between the sheet 3 and the hull 2. When the ship is positioned according to the invention, the bow and stern are closed to create a confined space that will prohibit water from the outside to enter into the confined space where the vessel is to be disinfected. One way to solve the closing/opening is to use a winching mechanism to raise/lower the sheet in the stern 27 up to surface level as seen in figuer 2C or down to a low level to enable vessel to pass in or out. According to the invention, it is ensured that the confined space is maintained even during hard environmental conditions comprising waves and stream effects.

Another way to open/close the stern and/or the bow end according to the invention is that the floating elements and the sheet in bow and/or stern end can be movable to open and close in a lock gate manner.

In one embodiment of the invention, the generation of the disinfection agent is done in a production/mixing unit 19 on board of the vessel that is to be disinfected. The disinfection agent or solution is transferred to the coupling device 25 that enable the disinfection agent or solution to be transported to the diffusion hoses and pipes 5. As seen in figure 2B and 2C, the disinfection agent or solution is floating in the direction of the arrows 26 from the generation/mixing unit 19 to the diffusion hoses or pipes 5.

In another embodiment, the production/mixing unit is located on the floating dock itself or somewhere apart from the vessel or the floating dock.

According to another possible embodiment of the present invention, the embodiment will use the lowering of the vessel position in the water by i.e. filling the ballast tanks and/or cargo tanks with water, and thereby decrease the space between the sheet and the hull. Measuring the distance between the sheet and the hull enables the operator to get a good estimation of the volume of the confined space between the sheet and the hull. One alternative to ensure/measure correct space between the sheet and the hull is to measure the strain on the sheet when the vessel is lowered onto the sheet and the hull makes contact with the spacers 6. Using sonar/echo or other electronic measuring equipment may also be used for the task of estimating the volume of the confined space.

According to another possible embodiment of the present invention, the embodiment will use one of the described sheet mechanisms that also ensure a maximum distance between the sheet 3 and the vessels outside hull 2 at any given place. One way to achieve this is to configure the sheet 3 to fit around the vessel's outside hull in a manner that permits only a defined maximum distance between the sheet 3 and the vessel's outside hull 2.

Another possible embodiment of the present invention is a submerged dock with a sheet formed to the configuration of the vessel's hull such that when the submerged dock receives the vessel the sheet will enclose it partly or entirely. The floating elements 18 may include the function of winding / tightening the sheet 27 and thereby decreasing the space confined between the sheet 3 and the hull 2. When the ship is positioned according to the invention, the sheet in the bow and/or the stern are closed to create a confined space that will prohibit water from the outside to enter into the confined space where the vessel is to be disinfected.

According to the invention, it is ensured that the confined space is maintained even during hard environmental conditions comprising waves and stream effects. When vessel is partly or entirely enclosed, the disinfection process is initiated and executed.

One possible embodiment of the present invention is a submerged dock 2A, 2B and 2C with a sheet with a generic form configured to be used with a variety of different forms of vessels hull such that when the submerged dock receives a vessel the sheet will enclose it partly or entirely. The floating elements 18, 22 may include the function of winding / tightening 27 the sheet and thereby decreasing the space confined between the sheet 3 and the hull 2. When the ship is positioned according to the invention, the bow and stern are closed to create a confined space that will prohibit water from the outside to enter into the confined space where the vessel is to be disinfected.

According to the invention, it is ensured that the confined space is maintained even during hard environmental conditions comprising waves and stream effects.

When the vessel is partly or entirely enclosed, the disinfection process is initiated and executed.

Another possible embodiment of the present invention is to use one of the described sheet mechanisms and perform the cleaning and disinfection by using other chemicals, agents or poisons, such as rotenone, saponins, TFN (3-trifluoromethyl-4-nitrophenol), niclosamide, Bayluscide (a proprietary name for the ethanolamine salt of niclosamide), Fintrol, Rotenol and others, than ozone. Then diffuse the selected chemicals, agents or poisons in the water 9 between the sheet 3 and the outside of the vessel's hull 2 at intervals to enable all parts of the said submerged parts of the hull 2 to be in contact with the disinfection agent for required time period. This may require the diffusion of disinfection agent at multiple or other locations inside the sheet 3. If the disinfection agent is denser than water 20, diffusion must be at surface level to enable treatment of all parts of the hull submerged in water.

According to one possible embodiment of the present invention described in figure 3 and figure 4, the excess disinfection agent from the described embodiments will rise to the water surface and diffuse into the air above the water surface. The outside of the hull that is not submerged in water can also be infected and in need of disinfection. A physical cover 11 extending the sheet 3 function above the water surface 17, covering the area of the outside of the hull exposed to contamination with overlapping ability 12, will keep the diffused disinfection agent from the water close to the outside of the hull 2. The airborne disinfection agent will then disinfect the outside of the hull 2 that is above the surface 17 of the water and that is exposed to the disinfection agent for the required time period. Alternatively can the sheet 3 be extendable such that it is able to cover part or the whole of the part of the hull that is not submerged in water. This can optionally be achieved by an extension sheet/cover attached to the floating elements or stored at another place for setup when needed.

Yet another way to ensure disinfection of the parts of the hull not submerged in water is to facilitate spraying with disinfection solution the desired surfaces not treated by the disinfection solution between the sheet 3 and the hull 2. The spraying operation may be fed with disinfection solution from the generating/mixing unit 19, the confined space between the sheet 3 and the hull, the ballast and/or the cargo tanks, or other any other supplying method/source.

According to another possible embodiment of the invention, the disinfection solution can be delivered to the space between the sheet and the hull from the ballast and/or the cargo tanks on board and/or the generating/mixing unit 19. Often when a disinfection process is required, it is also necessary to clean out the ballast tanks and the cargo hulls of the vessel. This is often achieved by filling the ballast tanks and the cargo tanks with a disinfection solution, i.e. ozone saturated water. The disinfection solution can be pumped out through valves in the hull, normally positioned in the stern of the vessel, and thereby into the space between the sheet and the hull of the vessel. At the same time the water intake, normally positioned at the bow of the vessel, may lead the water from the space between the sheet and the hull of the vessel. This water can in turn be returned to the ballast and/or the cargo tanks of the vessel. It is thus possible to create a circulation stream that ensures the disinfection agent streaming along the whole length of the outside of the hull with greater precision.

According to another aspect of the invention, it is required to ensure sufficient high concentration of the disinfection agent in a predefined time period around the whole outside hull of vessel. This is achieved by measuring the concentration of the disinfection agent in the disinfection solution. For example, when the disinfection agent is ozone, it is sufficient to measure the concentration level at the surface 17 of the disinfection solution at the hull side since the ozone will rise upwards alongside the hull and react with the organisms present as it rises to the surface. When the ozone concentration reaches and maintains a certain predefined level at the surface of the disinfection solution in a predefined time period, then all or required quantities of the organic material on the hull is extinguished.

One aspect of the invention is that when test samples of the disinfection agent, taken from the surface between the sheet and the hull of the vessel during the disinfection process, are analysed, it is possible to detect faults and defects in the sheet 3. Such faults and defects can be wholes and/or glitches that enables water from outside of the sheet 20 to enter and mix with the disinfection solution. If these wholes and/or glitches are too large it is not possible, or difficult, to achieve required level of concentration of the disinfection solution.

According to another possible embodiment the present invention can produce ozone as the disinfection agent in the layer between the sheet 3 and the outside of the hull 2, as shown in figure 4 when the sheet 3 has been positioned around the hull 2 by applying an electrical charge to electrodes 13,14 (anodes and cathodes) positioned close to the bottom of the sheet 3. The reaction will produce ozone, and even higher concentrations of ozone can be achieved by adding a high concentration saline solution 15 in the water around the electrodes.

According to another possible embodiment, the present invention can be used to disinfect net cages 42 as described in figure 8, or other installations such as fish farms, fish cages or parts of such installations partly or fully submerged in water. Figure 8 shows the net 41 of the net cage and the sheet 3 mounted around the complete net 41. An extension sheet 11 as shown in figure 4 can be applied to disinfect other parts of the installation not submerged in water including reeling 43.

According to another possible embodiment, the present invention can be used to disinfect buoys 50 as described in figure 9, or other installations or parts of such installations partly or fully submerged in water. An extension sheet 1 1 as shown in figure 4 can be applied to disinfect other parts of the installation not submerged in water.

According to yet another possible embodiment of the present invention the embodiment facilitates a method for production of ozone in the layer between the sheet 3 and the outside of the hull 2, as shown in figure 5, and when the sheet has been positioned around the hull, by applying an electrical charge to the electrodes: anode 13 and cathode 14 with an electrolyte 32 between the two electrodes. The electrodes can optionally be positioned in a prepared perforated space 33 in the sheet that enables water and optionally added saline solution to freely encompass the said electrodes. When an electrical charge 40 is applied as shown in figure 6 to the electrodes with the positive charge on the anode 13 and the negative charge on the cathode 14 then ozone will be generated at the anode, and hydrogen generated at the cathode. The same electrolysis reaction can be used to produce other disinfection agents/oxidants. These may comprise halogens such as Br, CI, BrCl and/or others. The embodiment can be used to facilitate treatments by multiple disinfection agents by changing the composition of the electrolyte surrounding the electrodes.

According to one possible embodiment of the present invention the generation of ozone by electrodes is shown in figure 7, where the ozone generated at the anode 13 rises through the water on the inside of the sheet 35, and if the inside of said perforated space 34 is configured to a tight fit around the electrodes the hydrogen generated at the cathode 14 will disperse into the water on the outside of the sheet 36, and thereby minimizing the potential of accumulation of hydrogen. The electrodes that are shown in figure 7 can be incorporated into the sinker weighting section 4 at the bottom of the sheet 3 described in figure 4, but is not limited to such position.

According to one possible embodiment of the present invention the embodiment is used to disinfect the outside of the hull 2 of ships 1 of length up to 100 meters used for transport to, from and between fish farms and use ozone as a disinfection agent and a sheet of tarpaulin or canvas or other material 3 with optionally high resistance to ozone. The sheet 3 may be stored on deck in a rolled up installation 16 as shown in figure 2, or may alternatively be stored on a suitable location on shore, on the ship or on a vessel. When the disinfection process is initiated the sheet is rolled out and placed around the outer side of the hull 2 by submerging it by means of sinker weights 4 at intervals provided in the sheet 3 and pulling ropes 10 that are attached to the sheet 3 at intervals or floating it in position. The sheet 3 also has floating elements 7 to ensure that the sheet 3 is extended the whole way up the ship hull's 2 outer side to the sea surface, thereby preventing leakage of external water into the enclosure once the diffusion of ozone has started. The sheet 3 will encompass all the parts of the outer side of the hull 2 that is immersed in water 20. Ozone is diffused at intervals throughout the enclosure that is filled with water 9 between the sheet 3 and the outside of the ship's hull 2. The ozone will mix with the water 9 until saturation and excess ozone will rise. The ozone, its reactive intermediates and associated compounds such as hypobromic acid, will oxidize and or destroy organic compounds including the inactivation of the organisms bound to or associated with the vessel's hull.

The ozone concentration level is maintained in the saturated water in the enclosure for the required period to achieve desired disinfection effect.

According to another possible embodiment of the present invention the embodiment is used to disinfect the outside of the hull 2 of ships of length up to 100 meters used for transport to, from and between fish farms and use ozone as a disinfection agent and a sheet 3 of tarpaulin or canvas or other material with optionally high resistance to ozone. The sheet 3 will be stored on deck, on shore or other in a manner such that it can be stowed away if desired when not in use. When the disinfection process is initiated, the sheet 3 is positioned around the outer side of the hull 2 by submerging it by means of sinker weights 4 at intervals provided in the sheet 3 and pulling ropes 10 that are attached to the sheet 3 at intervals or floating it in position. The sheet 3 also has floating elements 7 to ensure that the sheet 3 is extended the whole way up the ship hull's 2 outer side to the sea surface, thereby preventing leakage of external water into the enclosure once the diffusion of ozone has started. The sheet 3 will encompass all the parts of the outer side of the hull 2 that is immersed in water 20. Ozone is diffused at intervals throughout the enclosure that is filled with water 9 between the sheet 3 and the outside of the ship's hull 2. The ozone will mix with the water 9 until saturation and excess ozone will rise. The ozone, its reactive intermediates and associated compounds such as hypobromic acid, will oxidize and or destroy organic compounds including the inactivation of the organisms bound to or associated with the vessel's hull. The ozone concentration level is maintained in the saturated water in the enclosure for the required period to achieve desired disinfection effect.

The described embodiments and the details described in each embodiment are not to be used as limitations of the invention, but merely as examples of possible embodiments. Features that are described in the embodiments are not limited to the respective embodiment description, but are to be considered as features that can be used in any of the embodiments or in any other described scenario in this invention description or in the claims or figures.

Chemicals are often used as a disinfectant, and create a challenge when considering environmental protection. Introducing the use of ozone in this environment as the disinfection agent will increase the cleaning efficiency and eliminate the risk of pollution, as there are no residual environmentally toxic products.

In seawater the ozone will quickly react with the salt components, and in particular with Bromide (Br), and create active oxidant products. The disinfection effect is measured in TRO, Total Residual Oxidants.

The disinfection agent, preferably ozone, is kept at a selected concentration level to maintain required TRO for as long as required to inactivate organisms and

contamination attached to the outer side of the vessel's hull. The authorities governing the locations of where the vessels operate normally provide requirements and regulations for disinfection agents' concentration and the contact time for such agents to be applied.

When the term vessel is used, it is understood that the term also includes ships, boats, barges, floating devices, installations partly or completely submerged in water, such as fish farms, net cage, fish cage, buoys, or other aquatic installations or parts thereof.

When the term sheet is used, it is understood that the term also includes any form of tarpaulin, cover, sheet, shield or other suitable material for the purpose of separating the water surrounding the vessel and the layer of disinfection agent.

When the term to disinfect or disinfection is used, it is understood that the terms mean the activity of cleaning the surface of and neutralizing or inactivating any biological organisms associated with the object or area that are under treatment, and the said activity may not be 100% efficient.

When the term disinfection agent is used, it is understood that the term also includes ozone, oxidants, chemicals, agents or poisons such as rotenone, saponins, TFN (3- trifluoromethyl-4-nitrophenol), niclosamide, Bayluscide (a proprietary name for the ethanolamine salt of niclosamide), Fintrol, or any type of gas, liquid or any mix tehreof that has disinfection capabilities.

When the term outside of the hull is used it is understood that the term also includes installations that will be in contact with the disinfection agent when the device is mounted on the vessel, such as the nets of a fish farm, the body of a buoy, the hull of a ship, the sides and the top of an underwater seabed installation or the complete water exposed parts of a free floating fully submerged installation, or any other body partly or completely submerged in water.

When the term submerged dock is used, it is understood that the term also includes mobile dock and fixed or fastened/ anchored dock.

The generation of disinfection agents by electrolysis and the injection of disinfection agents into water for purification are commonly known.

Ozone is one of the strongest oxidants and disinfectants available. Although ozone is only partially soluble in water, it is sufficiently soluble and stable such that its oxidation or disinfectant properties can be fully utilized. After ozone oxidizes or disinfects, it decomposes into oxygen. Ozone reacts with a large variety of organic compounds resulting in oxygen-containing organic by-products.