Patent Application
20080229995
This invention relates to systems and methods for use during in-water cleaning/scrubbing of a vessel hull, in particular for controlling contaminants released from the vessel hull during cleaning so as to minimize any environmental impact thereof.
Many marine vessels have a limited lifetime of service, after which they can be used as floating museums, rescued for dry dock storage, or more likely, destroyed. Before a vessel can be transported for subsequent destruction, invasive species and hazardous materials must be removed from its hull. Methods currently being used for in-water cleaning of the hull releases contaminants into the water body. This is an unacceptable situation for all governmental agencies, and poses environmental harm.
It would be desirable to design a system that would allow for efficient in-water hull cleaning to be performed, while also trapping substantially all contaminants so as to minimize the environmental impact of the hull cleaning process.
The present invention is directed to overcoming this and other deficiencies in the art.
A first aspect of the present invention relates to a system for use during in-water scrubbing of a vessel hull. The system includes: a curtain formed of a substantially impermeable fabric material, the curtain being sized and configured whereby, upon installation about a vessel hull, the curtain is capable of encircling the vessel in its entirety to define a confined region; a fluid pump having an inlet in fluid communication with the confined region defined by the curtain; and one or more ports that deliver water into the confined region during operation of the fluid pump.
According to this first aspect of the present invention, the system may further include any one or more of the following components: a plurality of support members having an end capable of being coupled to a vessel hull; a plurality of flotation members coupled to the curtain; and a filtration system for filtering water removed from the confined region by the pump.
A second aspect of the present invention relates to the combination of a vessel having a hull and the system according to the first aspect of the present invention, wherein the vessel and the curtain are positioned in water, with the curtain encircling the vessel in its entirety to define the confined region.
A third aspect of the present invention relates to a method of cleaning a vessel of a hull. This method includes the steps of: installing a system according to the first aspect of the present invention about a vessel, with the curtain encircling the vessel in its entirety to define a confined region; cleaning the hull of the vessel to remove debris; and withdrawing water from the confined region to recover debris removed from the hull during said cleaning. The withdrawn water can be filtered on site, treated if necessary, and returned to the body of water. Recovered debris can be disposed in accordance with environmental regulations.
The present invention preferably utilizes a modified version of the Gunderboom® Particulate Control System (PCS™) (available from Gunderboom Incorporated, Anchorage, Ak.). A system containing the PCS™ will enclose the hull using a modular, non-permeable, structure. The system is preferably designed to allow adequate space for divers to clean the hull using traditional hull scrubbers. Debris from cleaning will be trapped in a debris collection trough where the material is removed by pumping water and contaminants through a filter system that is designed based on pre-deployment chemical, physical, and biological analysis (i.e., a filtration suitable for the task presented by the particular ship being cleaned). The rate of discharge will be designed to create a “negative pressure” inside the enclosure. This negative pressure will prevent the release of contaminates should a breach of the enclosure occur.
Pre-deployment activities include taking samples in several locations of material that will be removed from the hull during the process. Chemical, biological, and physical analysis can be performed to ensure that an appropriate filtering system can be designed and installed for use during the process.
Filtered make-up water ports will be designed based on the flow rates of the filtered discharge system and the desired negative pressure. Negative pressure can be monitored using instrumentation and visual monitoring. Alarms will be installed to notify personnel of sudden drops in negative pressure indicating the possibility of a breach of the enclosure.
The present invention relates to a system for use during in-water scrubbing of a vessel hull, and the use of such a system, as installed on a vessel, for scrubbing the vessel hull.
The system of the present invention generally includes a curtain, one or more stabilizing components that maintain the position of the curtain about the vessel, a fluid delivery system that allows for removal of the waste water and contaminants from inside the confined region and their delivery to an appropriate filtration system.
The curtain is preferably formed of a substantially impermeable fabric material, where the curtain is sized and configured such that upon installation into a body of water about a vessel, the curtain is capable of encircling the vessel in its entirety to define a confined region.
The curtain is preferably of a desired length and height such that the curtain can be assembled in a body of water, and then moved into location to surround the vessel with a sufficient distance between the curtain and the vessel hull. With the ends of the curtain brought together, the ends and lower edges can coupled using a boom curtain zipper connection of the type described in U.S. Pat. No. 6,739,801 to Dreyer et al., which is hereby incorporated by reference in its entirety. A single zipper system can be used to join together both the ends and the lower edge of the curtain material, or two or more zipper connections can be used (i.e., one for the ends, and one for the lower edge).
Alternatively, the curtain can be formed of a series of distinct panels that can be connected together along their adjacent side edges via zipper connections of the type described in the above-referenced U.S. Pat. No. 6,739,801 to Dreyer et al. The panels are also preferably aligned in pairs, one on either side of the vessel, so that the lower edges of the panels can be connected together along the length of the vessel. Given the negative pressure within the confined region, as described below, the zipper connections need not be water-tight to prevent contaminants from passing outside the confined region. However, the placement of one or more overlapping flaps of curtain material over the zipper, on the interior of the curtain surface, will prevent contaminants from being trapped in the zipper components.
The curtain or curtain panels can be formed of any suitable fabric material that is substantially impermeable to debris removed from the hull. Preferred fabric materials include geosynthetic materials, and particularly preferred are those that are substantially impermeable to materials larger than about 10 microns. An exemplary geosynthetic material is that which is available from Gunderboom Incorporated (Anchorage, Ak.) and sold as a Particulate Control System (PCS™). This same material is available from Seaman Corp. (Wooster, Ohio) under the tradename XR-5®.
Geosynthetic materials of this type can also be coated with polymer coatings to render them substantially impermeable to water. A number of such polymer coatings are known in the art including, without limitation, polyurethanes, polyamides, etc.
The curtain preferably is constructed such that it defines a trough, or a material settling area, that is positioned substantially beneath the vessel. It is from this trough that debris is preferably removed from the confined region. The trough can be formed using adjustable straps that are connected to the curtain (or curtain panels) and span from the starboard side of the vessel to the port side of the vessel. Upon tightening of the straps to create slack at the lower edge of the curtain, the trough will be formed.
The curtain is also preferably equipped with a plurality of ports that allow water to flow from outside the curtain into the confined region. This flow of water through the ports is used to at least partially offset the negative pressure created by withdrawal of water from the confined region during pump operation. The ports are preferably distributed about the perimeter of the curtain, more preferably uniformly about the perimeter.
The ports can have a number of configurations. According to one approach, the port is simply a weir over which water can flow into the confined region. This can be integrated into the curtain design by modifying the top edge of the curtain at locations about the perimeter of the curtain. Basically, no flotation system is provided at the site of the weir, and the curtain can be cut such that the top edge of the curtain at the weir lies at or just below the water surface. During use, the negative pressure will allow water to flow over the weir into the confined region.
According to another approach, the port can be formed in the curtain itself, by creating a series of “windows” that are formed of a different fabric material that is water-pervious. Although any number of water-pervious geosynthetic fabrics can be used, one preferred fabric is Propex 4508 available from Propex Fabrics Inc. (Austell, Ga.). These “windows” can be formed along the upper edge of the curtain (i.e., at or near the water line. Placement of these ports near the water line helps to maintain the flow of water and debris from the surface toward the trough where waste water and contaminants are removed. The “windows” can also include covers that effectively reduce the available surface area for “make-up water” entering across the curtain into the confined region. The covers, positioned on the external surface of the curtain, can be adjustable in nature to regulate flow rate into the confined region.
Regardless of the embodiment, the number of ports required can be selected, i.e., based on operation of the pump, to maintain a suitable “negative pressure” inside the confined region.
The one or more stabilizing components can include any one or more of the following: anchors tethered to the curtain; a plurality of support members coupled to the vessel hull, which can be connected to upper portion of the curtain; a floating support system to maintain the upper edge of the curtain above the water line; and one or more ballast components secured to the curtain.
The plurality of support members have one end capable of being coupled to a vessel hull. In particular, the end of the support members can be in the form of a plate of suitable size and configuration for welding to the vessel hull, or the end can be in the form of a magnet that is strong enough to support the curtain during use. The latter is preferred, because the support members can more easily be re-used, and the installation and removal of the system from the vessel is much simpler. The other end of each support member includes a tether that is connected to the upper edge of the curtain. Depending upon the purpose of the support members, the tether can be used to simply maintain position of the curtain (i.e., low load) or the tether can be used to support the weight of the curtain (i.e., high load). Thus, in certain embodiments, these support members 18 can be used to support the curtain in its entirety. In other embodiments, these support members can simply be used to maintain the curtain away from the side of the vessel. In the latter case, the curtain also preferably contains a floating support structure that maintains the top of the curtain above water.
The floating support structure can include a plurality of conventional flotation units, such as inflatable devices, air bags, and floats made from buoyant materials, such as cork, synthetic foams, and other plastics. A preferred material is expanded polystyrene (“EPS”), which is especially suitable for use as the flotation unit. It is desirable to coat or seal the EPS to prevent deterioration associated with prolonged exposure to the elements. EPS is commercially available from ARCO Chemical Company as DYLITE™ and can be formed or molded into flotation units of various sizes and shapes (e.g., cylindrical, square, etc.) as required by project design. The EPS has a positive buoyancy that keeps the flotation unit substantially above the water surface at all times, allowing the flotation unit to ride the waves, even in adverse conditions. An EPS flotation unit is not deformed by wave action and does not lose buoyancy if punctured, as would an inflatable device. A single cubic foot of EPS can support as much as 60 lbs. A commonly used size of flotation unit of EPS is an 8″ to 12″ diameter cylindrical configuration, but the size can be readily adapted to meet specific wave and environmental conditions and depth requirements. To accommodate the installation of flotation units into the boom curtain, the upper portion of the boom curtain can be provided with an upper sleeve that includes a series of slits along its length.
Ballast chains and other weighted materials can be provided to maintain position of the curtain during use. The ballast can be attached externally or internally of the curtain at various locations. Attachment can be effected by providing pockets into which the ballast can be introduced (i.e., at the time of installation), or loops of curtain material can provide an attachment point for coupling the ballast via lines or cable. The ballast can minimize curtain movement resulting from the negative pressure within the confined region, and promote flow of water through the ports.
The fluid delivery system can include a fluid pump stationed on a support barge or upon shore, depending upon the particular environment in which hull cleaning occurs. The pump is preferably capable of removing water and debris via a suitably sized conduit whose end is in fluid communication with the confined region, preferably at the center of the trough. One or more pumps can be used, and one or more conduits can be used along the length of the trough. The output from the pump can be delivered to a filtration system or, alternatively, the waste water can be pumped into a storage vessel for subsequent treatment of the waste water and recovery of the debris.
Regardless of whether the waste water and debris is treated on site or at a remote location, the waste water is preferably passed through a filtration system. Depending on the nature of the debris and contaminants, the filtration system can include a solid filtration system, a chemical filtration system, a biological purification system, or a combination thereof.
Referring now to
The curtain 12 is formed of a geosynthetic material as described above, which is substantially impermeable to debris and resist or precludes the flow of water therethrough. As noted above, the curtain 12 is preferably of modular construction, but once assembled (as shown) the curtain extends about the entire perimeter of the vessel. Once assembled and positioned about the vessel, the curtain can be maintained a sufficient distance away from the vessel hull by the various types of stabilizing components noted above.
The upper edge of the curtain 12 includes a sleeve 22 that is formed by folding the curtain over and securing the edge to itself (see
Attached to the interior of the curtain, and extending in a port to starboard orientation, is a plurality of straps 24. These straps 24 can be adjustable straps or they can be fixed length. Preferably, the straps 24 are capable of being coupled together using a quick connector coupling. The location and orientation of the straps 24 are such that they cause the formation of a trough 26 positioned beneath the vessel hull.
To help maintain the curtain away from the vessel hull, a plurality of ballast 20 are secured to the curtain about the perimeter thereof. As shown, the ballast 20 is positioned on the interior side of the curtain, and can be located in a pocket or the like formed thereon. As an alternative, or in addition, ballast can be tethered to the external side of the curtain and suspended therefrom.
Referring specifically to
Spaced about the perimeter of the vessel hull, and located above the water line, is the plurality of support members 16. These support members effectively behave as outriggers that space the top of the curtain 12 away from the vessel hull. As shown in
As shown, the fluid pump 14 is stationed on a support barge. The pump is preferably capable of removing water and debris via a suitably sized conduit 40, which extends between the pump and the trough 26. Consequently, debris and waste water are removed from the confined region, and then delivered into a filtration system. The filtration system can be included within the larger pump assembly (as shown) or it can be a separate unit, in which case an outlet from the pump delivers fluid directly to the filtration system, and the outlet from the filtration system can be discharged into the water. Although only one pump (and filtration system) is shown in the figures, it should be appreciated by persons of skill in the art that more than one pump (and its associated filtration system and conduit in communication with the trough) can be utilized.
In use, the system of the present invention will be installed about a vessel, with the curtain encircling the vessel in its entirety to define a confined region. Assembly of the curtain will be carried out as described above. The system can be assembled substantially as illustrated in
As a consequence of withdrawing water from the confined region, a negative pressure gradient is maintained within the confined region. This ensures that any breach of the curtain barrier will minimize contamination outside the confined region. In addition, through the use of the one or more ports, the degree of the negative pressure can be regulated by controlling the flow rates of water into the confined region through the one or more ports.
The entrance of water through the ports also has the effect of creating a downward current along the sides of the curtain, moving debris on the curtain toward the trough for removal. The trough can optionally be provided with a layer of fluid-pervious geosynthetic fabric material that would prevent large debris from entering the conduits and pump system. This can be the same type of material used for the ports, e.g., Propex 4508. Such large material can be removed by the operators.
At the completion of hull cleaning, the interior surface of the curtain can be vacuumed to remove hull debris. The vacuum equipment can be of the type used in swimming pools. Any geosynthetic materials that are water-pervious can be removed and disposed as hazardous waste in accordance with all applicable laws and regulations. Water-pervious geosynthetic fabrics would then be replaced before subsequent use of the system on a different cleaning project.
Water and debris withdrawn from the confined region can either be stored for subsequent treatment, or be treated on-site and discharged into the body of water (i.e., either inside or outside the confined region. Preferably, the treatment includes the passage of water withdrawn from the confined region through a filtration system. Depending on the nature of the debris and contaminants, the filtration system can include a solid filtration system, a chemical filtration system, a biological purification system, or a combination thereof.
Although preferred embodiments have been depicted and described in detail herein, it will be apparent to those skilled in the relevant art that various modifications, additions, substitutions, and the like can be made without departing from the spirit of the invention and these are therefore considered to be within the scope of the invention as defined in the claims which follow.
This application claims the priority benefit of U.S. Provisional Patent Application Ser. No. 60/896,122, filed Mar. 21, 2007, which is hereby incorporated by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 60896122 | Mar 2007 | US |
