Underwater surface cleaning vehicle for integrated cleaning and effluent treatment system

A method and apparatus for the cleaning of an underwater surface, such as a hull. The method and apparatus enables cleaning to be conducted while mitigating the release of removed material into surrounding waters. The integrated apparatus includes a cleaning deck for removing fouling from the underwater hull surface, and a pre-processing deck with integrated components for the processing of cleaning effluents. According to the method and apparatus, materials removed by the shroud are sucked into the pre-processing deck, crushed, and separated into a separator effluent that may be recycled to the shroud, and a concentrate, which is discharged to a land treatment unit for further processing.

TECHNICAL FIELD

The following description relates generally to an underwater surface cleaning vehicle, and in particular to an integrated underwater surface cleaning vehicle having a pre-processing unit for the initial processing of cleaning effluents.

BACKGROUND

Navy ships are periodically cleaned using open cycle cleaning devices such as, for example, submerged cleaning and maintenance platform (SCAMP) technology that utilizes integrated impeller and cleaning brush technology and results in the direct discharge of removed constituents such as, for example, biological fouling, hull coatings, and corrosion byproducts into surrounding water. Most antifouling coatings utilize heavy metals such as Cu and Zn as biocides that are released during cleaning operations at levels that can exceed water quality criteria. This has prompted governments to develop standards to manage this discharge or, in some cases, to prohibit open water cleaning of hulls with coatings that have antifoulants in them without special permission.

Waterborne underwater hull cleaning is critical to the worldwide operation and maintenance of Navy ships and impacts operating capability (e.g., speed and maneuverability), acoustic signature, fuel efficiency and the maintainability and lifecycle of critical systems including underwater hull coatings, impress current cathodic protection systems, and propulsion systems.

SUMMARY

Disclosed are systems and techniques for conducting advanced waterborne underwater ship hull and other submerged or partially submerged surface cleaning using integrated surface contaminant removal, capture, containment, collection, comminution, concentration, separation, reuse and transport technology. The concentrate stream generated is transported for subsequent processing for recycle or disposal at a substantially reduced volume. This invention mitigates the release of toxicants and other material during the waterborne hull cleaning operations.

In one aspect, the invention is a cleaning vehicle for cleaning an underwater surface. In this aspect, the cleaning vehicle has a pre-processing deck and a cleaning deck or shroud pivotally connected to the processing deck. The pre-processing deck includes one or more circulation pumps downstream of the cleaning deck for initiating the suctioning of the cleaning deck onto the underwater surface and for initiating a particulate flow of water entrained material removed by the cleaning deck. The invention further includes a solids-processing unit downstream of the cleaning deck for crushing and fracturing solids in the particulate flow. Additionally, the apparatus includes a separator unit downstream of the solids-processing unit for partitioning the particulate flow into a separator effluent and a concentrate of crushed material. According to the invention, the cleaning deck has one or more abrasion devices for removing fouling from the underwater surface, and a deck mouth for the intake of the particulate flow of water entrained material.

In another aspect, the invention is a method of cleaning an underwater hull surface using a cleaning vehicle having a pre-processing deck and a cleaning deck pivotally connected to the processing deck. The pre-processing deck has one or more circulation pumps, a solids-processing unit, and a separator unit. The cleaning deck comprises one or more abrasion devices and a cleaning deck mouth. In this aspect, the method includes the drawing of the cleaning deck into contact with the underwater surface by using the one or more pumps to generate a reduced pressure between the cleaning deck and the underwater hull surface. The method also includes the removing of fouling from the underwater hull surface by applying the one or more abrasion devices to the underwater hull surface. The method further includes the generating of a particulate flow of water entrained material removed by the one or more abrasion devices, by using the one or more pumps to draw the removed material and surrounding water, and the crushing and fracturing in the solids-processing unit, solid material in the particulate flow. The method further includes the partitioning in the separator unit the particulate flow into a separator effluent and a concentrate of crushed fouling material.

Other objects, features, and advantages will be apparent from the description and the drawings.

DETAILED DESCRIPTION

The described systems and techniques entail an underwater cleaning and integrated water and solids capturing, containing, comminuting, separating, concentrating, reusing and transferring process for conducting waterborne underwater cleaning. By design, the below-described method and apparatus enables cleaning to be conducted while mitigating the release of removed material into surrounding waters.FIG. 1is an exemplary flow diagram of an integrated hull cleaning and effluent system100for performing the above-recited functions.

As illustrated inFIG. 1, the system100includes a ship hull110having a hull surface111, the ship hull docked in relatively close proximity to a pier140. The system100further includes a cleaning vehicle120having two parts (decks), a cleaning deck or shroud122and a pre-processing deck124. The cleaning deck122moves across the hull surface111to physically remove fouling and other undesired buildups from hull surface. The pre-processing deck124, via a reduced pressure gradient, sucks the particulate flow of removed fouling material and other cleaning material such as antifoulant coatings having heavy metal toxicants, along with surrounding water through the cleaning deck122into the pre-processing deck124. The surrounding water may be seawater, freshwater or another type of water depending on the environment in which the ship is docked. A flexible hose123may facilitate the transportation of the water entrained material or slurry from the cleaning deck122to the pre-processing deck124. As will be outlined below, the pre-processing deck124treats the water entrained material, separating the particulate flow into a separator effluent and a concentrate of crushed fouling material. The separator effluent is directed back towards the cleaning deck122via line127. Line127may comprise a flexible hose having a diameter of about 2 inches to 4 inches. The separator effluent may be reused to supplement further cleaning operations. Alternatively, the separator effluent may be discharged directly into the water.FIG. 1shows line130through which the concentrate of crushed fouling material is transported to a land treatment unit150, for subsequent processing of the concentrate. The land treatment unit150may be located on the pier. Alternatively, the land treatment unit150may be located on a ship such as a barge or on another platform. The line130may be a flexible hose of sufficient length and diameter, for example the hose may be about 400 feet to about 1000 feet in length, and about 1 inch to about 2 inches in diameter. Although the system100shows a ship hull110, the cleaning vehicle120may be used to clean other submerged surfaces.

FIG. 2Aillustrates a cleaning vehicle200(within the dotted box) including a cleaning deck or shroud220as well as effluent treatment devices downstream of the shroud220, for cleaning an underwater surface, such as a hull surface.FIG. 2Ashows a schematic illustration of the elements of the cleaning vehicle200according to an embodiment of the invention.FIG. 2Ashows the cleaning deck220having cleaning units225, a solids-processing unit250downstream of the cleaning deck, a circulation and transfer pump unit260, also downstream of the cleaning deck, which may be one or more pumps. The pump260is directly coupled to the solids-processing unit250. The cleaning units may include one or more brushing devices and/or one or more nozzles.FIG. 2Aalso shows a separator unit270downstream of the solids-processing unit, which may be a hydrocyclone or similarly robust phase separator device.FIG. 2Aalso shows conduit lines209,210,211, and212. The conduit lines may be flexible hoses with line209connecting the cleaning deck220to the solids-processing unit250, and line210connecting the circulation pump260to the separator unit270. Line211also connects the separator unit270to the cleaning deck220. As shown, line211is a split line that is connected to the nozzles227. Line212connects the separator to a land treatment unit300. The land treatment unit300may be located on a pier in the vicinity of the docked ship. Alternatively, the land treatment unit300may be situated on a ship such as a barge, or on another platform. Lines209and210convey a particulate flow from the cleaning deck to the separator unit, and line211conveys recycled separator effluents to the cleaning deck220. The diameter of the lines209,210,211,212may be adjusted to properly regulate flow-rates and maintain required pressure differences. For example, the diameter of the line211may be about 1.5 times the diameter of line212, with line211having for example, a diameter of about 3 inches to about 4 inches and line212having a diameter of about 1.5 inch to about 2.5 inches, with line210having a diameter of about 3 inches, and line209having a diameter of about 4 inches. In one particular embodiment, lines210and211may have a diameter of about 3 inches and line212has a diameter of about 2.0 inches.

FIGS. 2B and 2Cshow side and top views respectively of the cleaning vehicle200according to an embodiment of the invention.FIGS. 2B and 2Cshow the arrangement of the various elements on the cleaning deck or shroud220and the pre-processing deck240, as well as the arrangement of the cleaning deck220and the pre-processing deck240with respect to each other.FIG. 2Bshows the cleaning deck220attached to the pre-processing deck240via a linkage member230, which may allow for pivotal movement. The linkage member230may include a bar linkage arrangement to control the displacement of the cleaning deck220with respect to the pre-processing deck240.FIGS. 2B and 2Cshow the cleaning deck having guide wheels229, a diver control unit236, and a guard/hand rail237to enable an operator to safely and properly control and maneuver the cleaning deck220. As shown, the cleaning deck200also has a deck seal228to maintain a reduced-pressure contact with the hull surface.FIGS. 2B and 2Cfurther illustrate a discharge opening or port233for discharging the particulate flow, via a conduit such as210shown inFIG. 2A, from the cleaning deck220to the pre-processing deck240. The top view ofFIG. 2Cshows recycling ports235for receiving recycled separator of via a conduit such as211shown inFIG. 2A, from the pre-processing deck240.

FIG. 2Dalso shows the arrangement of the various elements on the cleaning deck220according to an embodiment of the invention.FIG. 2Dshows a deck suction mouth222for the intake of the particulate flow of water entrained fouling and other cleaning material. Also illustrated are reciprocating or rotating brushes224. The brushes224may be arranged in a circular manner and may comprise of steel, polypropylene, combinations thereof, or any other material used for bristles in brushes. The brushes are powered by one or more brush motors226, as shown inFIG. 2C. TheFIG. 2Dalso shows discharge nozzles227for directing and discharging recycled separator effluent. The nozzles227are configured and positioned to direct the discharge so that the discharge flow flushes material and other material from the brushes224. Additionally, the discharge flow from the nozzles227creates a water-current which directs into the deck mouth222, material cleaned from the hull surface111. Alternatively, the nozzles227may be directed to discharge the fluid directly onto the hull surface111to assist in the direct removal of fouling deposits. AlthoughFIG. 2Dshows three brushes224, the cleaning deck220may contain as many brushes as desired, including less than three brushes or more than three brushes. Similarly, regarding the nozzles227, the cleaning deck220may include as many nozzles as desired.

As stated above, the different elements of the pre-processing deck240are also shown inFIGS. 2B and 2C.FIG. 2Bshows the deck240having a solids-processing unit, which is a crusher255.FIG. 2Balso shows the crusher motor256and crusher control lever257for operating the crusher255. The crusher255crushes and fractures solids removed during cleaning to for example, about ⅜-in or smaller, while having minimal impact on flow. Incoming solids to be processed can be significant in size, for example as large as 4 inches.FIG. 2Balso shows a circulation pump265, which may have a drive of about 30 HP. The pump265initiates the flow needed to generate shroud suction, the particulate flow of water entrained material, and subsequent downstream pressures for solids separation, separator fluid discharge or reuse, and concentrate transport.

FIG. 2Cshows the pre-processing deck240having a separator unit, a hydrocyclone275. The hydrocyclone275separates, concentrates and partitions the water entrained material into a separator effluent or overflow and concentrate or underflow streams.FIG. 2Calso shows the deck240having an underflow discharge port276that discharges the concentrate towards the land treatment unit300, and overflow discharge port277that discharges/recycles the separator effluent to the shroud220.

The above outlined apparatus for the cleaning vehicle200enables the cleaning operation in the shroud220, which involves simultaneous brushing, overflow injection, slurry evacuation while maneuvering across the surface to be cleaned. In operation, the cleaning vehicle200incorporates the simultaneous application of mechanical and hydrodynamic energy to remove fouling, and uses a differential pressure to induce fluid flow for evacuating removed material. The cleaning vehicle200further utilizes the direct injection and diffusion of processed working fluid to increase efficiency and enhance the transport of removed material from the working surface to the shroud220through the mouth222. A method of cleaning an underwater hull surface that incorporates the above-described cleaning vehicle200is outlined below.

FIG. 3is a flowchart of a method300of cleaning an underwater surface, such as a hull, according to an embodiment of the invention. The method300of cleaning involves the use of the cleaning vehicle200as outlined above, i.e., a cleaning vehicle having a pre-processing deck240and a cleaning deck220connected to the processing deck. The pre-processing deck240has one or more circulation pumps (260,265), a solids-processing unit (250,255), and a separator unit (270,275). The cleaning deck220comprises one or more cleaning devices225, and a cleaning deck mouth222.

As shown inFIG. 3, step310is the positioning of the cleaning deck/shroud220into a reduced pressure contact with the hull surface111. A diver performs this function, after submerging the cleaning vehicle in the water by known means, such as a crane for example. As outlined with respect to the embodiments ofFIGS. 1,2A,2B, and2C, the pre-processing deck240includes one or more circulation pumps (260,265) that create a suctioning force through the mouth222of the cleaning deck. Consequently, when a diver brings the cleaning deck220into contact with a hull surface111, a suction-like working contact is created between the hull and the deck because of the reduced pressure created by the one or more pumps (260,265).

Step320is the removing of fouling from the hull surface111. As shown in the embodiments ofFIGS. 2A-2D, the shroud includes cleaning units225that comprise motorized circularly arranged brushes224that are mounted for rotational or reciprocating movement. The scrubbing or sweeping action of the brushes removes the fouling from the hull surface111. Step330is the generating of a particulate flow of water entrained fouling material. The pressure created by the one or more pumps (260,265) draws fouling and other cleaning material such as antifoulants removed by the brushes, into the mouth222of the cleaning deck220, with the material entrained in a stream of surrounding water, which includes water peripheral to the cleaning deck and separator effluent injected into the deck. The particulate flow is sucked through the cleaning deck220towards the solids-processing unit (250,255) located on the pre-processing deck240. The particulate flow is sucked through the cleaning deck220at an appropriate rate, for example, at a rate of about 150 gallons per minute to about 170 gallons per minute. At step340, the solid material in the particulate flow is crushed and fractured in the solids-processing unit in a manner that has minimal impact on the rate of the flow. After passing through the solids-processing unit, the slurry of particulate flow is pumped to the separator unit.

At step350, the particulate flow including the crushed and fractured material is partitioned into a separator effluent or overflow and concentrate of crushed fouling material or underflow. The separator unit (270,275) may be hydrocyclone or a similarly robust phase separator device. To maximize the process, the slurry enters a processing device at an optimized flow rate, for example at approximately 50-65 psi. Step360is the discharging of the concentrate to a land treatment unit300for further treatment of the concentrate, and step370is the discharging of the effluent to the cleaning deck220or directly into the surrounding water. Steps360and370preferably take place simultaneously. Although the flow rates may vary as necessary, the separator effluent may be discharged at a rate of about 100 to 110 gallons per minute or higher, and the concentrate may be discharged to the land treatment unit300at about 50 to 60 gallons per minute. As outlined above, the concentrate is discharged to the land unit300via an appropriately sized flexible conduit or hose212of about, for example, about 600 feet in length and about 2.0 inches in diameter. An appropriately sized flexible hose having for example, diameter of about 3 inches may also be used to discharge the separator effluent to the shroud or to the water. As outlined above, diameters of the hoses assist in maximizing the different flow rates.

The described systems and techniques for waterborne underwater hull cleaning provide a means to mitigate the discharge of removed toxicants from underwater hull cleaning operations. This is accomplished by providing the integrated on-board processing of removed material while reusing working fluid to produce a single manageable wastestream concentrate that can be transported at relatively small flows, through, for example, flexible hose, over distances, for example, in excess of 600 feet, to a topside or other remote location where further wastestream management can be accomplished. The described systems and techniques improve upon long-standing technology that does not process or manage material removed during waterborne hull cleaning.

What has been described and illustrated herein are preferred embodiments of the invention along with some variations. The terms, descriptions and figures used herein are set forth by way of illustration only and are not meant as limitations. For example, the diameters of lines209,210,211, and212shown inFIG. 2A, may vary depending on operating conditions and requirements. For instance, line212may be made to be smaller or larger to accommodate for the varying sizes of the crushed solid particles in the concentrate. Additionally,FIG. 2Dshows three movable brushes for cleaning hull surfaces, but more or less than three brushes may be incorporated in the invention or other cleaning technologies such as waterjets, cavitating jets, ultrasonic transducers, or low pressure whips. Those skilled in the art will recognize that many variations are possible within the spirit and scope of the invention, which is intended to be defined by the following claims and their equivalents, in which all terms are meant in their broadest reasonable sense unless otherwise indicated.