Marine propulsion – Screw propeller – Shaft braking or locking
Reexamination Certificate
2002-04-09
2004-04-20
Sotelo, Jesus D. (Department: 3617)
Marine propulsion
Screw propeller
Shaft braking or locking
C210S757000
Reexamination Certificate
active
06722933
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention generally concerns the simultaneous control of both (i) the pressure and (ii) the content of ship's ballast tank gases to at different times kill both aerobic and anaerobic organisms within ballast water
The present invention particularly concerns establishing (i) a pressure less than atmosphere, called an “underpressure”, in the ullage spaces of ship's ballast tanks, and (ii) rendering inert the (underpressurized) ullage space gases of the ballast tank.
The present invention further particularly concerns accomplishing the (ii) inerting in a manner where dissolved gases in the ballast tanks' water will, in accordance with Henry's gas, (1) rapidly come into equilibrium with the inerted atmosphere of the ullage spaces, and (2) become sufficiently depleted in oxygen so as to broadly induce hypoxia in marine organisms within the ballast water. This condition can be indefinitely maintained.
The present invention still further particularly concerns optionally reversing this anoxic condition, and equally rapidly manipulating the ballast tank ullage space gases, and restoring such oxygen, to the ballast water as is commonly fatal to anaerobic marine organisms.
2. Description of the Prior Art
2.1 The Problem of the Importation of Exotic Species in Ship's Ballast Water
Many survey articles exist regarding the present, and potential, damage to the marine environment arising from the invasions of exotic, non-native, marine species within discharged ship's ballast water. One such article appears in the Gulf of Maine Times, Vol. 2, No. 2 as “Ballast water a vehicle for exotic species invasions”, and is excerpted below.
In that article it is explained that ballast water pumped onto a ship while it is in port contains marine species native to that area. When the water is later discharged into another port, those organisms can colonize there, affecting the ecosystem.
“Once every hour, about two million gallons [7.6 million liters] of ballast water which equals two million gallons of plankton from foreign ports is released in U.S. coastal waters. We refer to this as marine ecological roulette,” said James T. Carlton, professor of marine sciences at Williams College in Williamstown, Mass. He noted that the National Research Council in 1995 ranked exotic species invasion as one of five major issues in marine ecosystems management.
Ballast water is a necessary component of shipping. “When cargo is unloaded, the ship floats high like a cork. You put 15 to 35 thousand tons [13 to 32 thousand metric tons] of ballast water into it, depending on the size of the ship, to weight the ship to counteract the buoyancy, which gives the ship better stability and maneuverability,” explained Kevin Collard, Director of Operations, Environment and Safety for Marbulk Shipping, an international shipping company based in Salem, Mass.
But in an effort to prevent invasions of coastal ecosystems by non-native species, shippers are being urged to exchange their ballast water in the open ocean, so that the water they discharge into their next port does not contain organisms from their last one.
“The actual process which makes exchanging ballast water at sea effective is, you replace coastal water organisms with [less adaptable] mid-ocean organisms, which are less likely to survive in coastal waters,” said Lt. Larry Greene, Aquatic Nuisance Species Control Program manager for the U.S. Coast Guard (USCG).
Invaders can be devastating. “A typical ballast tank could be the size of an auditorium that seats 700 people,” said Carlton. When ballast water transfer takes place in port, the discharged water can introduce what he described as a “staggering diversity of living organisms,” to coastal waters, including non-native aquatic organisms and pathogens, such as cholera.
Not all of these organisms will survive in their new surroundings, but some are extremely hardy, have no natural predators in their new environment, and multiply profusely. Some invasive organisms can become toxic, posing threats to other species, aquaculture stocks, and humans. Non-native aquatic organisms can also crowd out native species by reducing the food supply or changing characteristics of the habitat.
The infamous European zebra mussel's introduction into the North American Great Lakes, and its subsequent spread to central U.S. rivers, has jeopardized commercial and recreational fisheries, and caused expensive infrastructure problems. The mussels consume huge amounts of microscopic plants and animals, reducing available food for other species, and they have become so prolific that power plants and water delivery systems have been forced to spend millions of dollars on removing them from underwater structures and water pipes.
In the Gulf of Maine, the European green crab, European periwinkle, Japanese sputnik weed, and grey and orange sea squirts, are all non-native species. Fortunately, none have caused problems on the scale of the troubles brought by the zebra mussel. Nevertheless, cautioned Carlton, without precautions, “It's only a matter of time until we register a front-page, major invasion in the Gulf of Maine. We are not able to predict what it will mean, so we'd rather it not happen.”
Mandatory compliance is coming. The International Maritime Organization (IMO) in 1991 adopted voluntary guidelines for preventing marine species invasions via ballast water, and is developing mandatory guidelines that may be approved as soon as 2000, although ratification may take several years.
Meanwhile, shippers entering U.S. ports were given three years to voluntarily comply with open ocean ballast water exchange guidelines under the U.S. National Invasive Species Act of 1996, which is enforced by the USCG. The Act states that shippers should exchange ballast water at sea unless “that exchange threatens the safety or stability of the vessel, its crew, or its passengers.” Reporting of ballast water exchange is now mandatory.
Researchers are exploring remedies for ballast water issues. Allegra Cangelosi, Senior Policy Analyst and co-principal investigator with the Great Lakes Ballast Technology Demonstration Project, is testing the effectiveness of filtering organisms from ballast water.
Open-ocean ballast water exchange is simply not feasible in all cases due to weather conditions, routing, or a ship's structure, Cangelosi said. “We are in desperate need of more broadly applicable approaches,” she said, adding that her organization is “looking for technologies that can be used anywhere on the globe,” including the Gulf of Maine.
Battelle Memorial Institute, a not-for-profit international organization, is also researching ways of treating ballast water as it is pumped onto a vessel to kill the organisms in the water, including ultrasonic treatment, irradiation, and heating the water, said Deborah Tanis, a research scientist based in Battelle's Duxbury, Mass. office.
Treating ballast water chemically may also be an option, but Carlton said, “We want to be conservative with biocides and cautious about diverting more chemicals into the system unless they have a very short half-life and are biodegradable.”
Though open-ocean exchanges are currently the accepted method for handling potentially contaminated ballast water, both Tanis and Cangelosi agree that other options are needed. Said Tanis, “We need methods that are more effective than ballast water exchange and more feasible for shippers. We're studying the actual biological effectiveness of exchanges. It certainly will help, but I don't know that it's 100 percent foolproof. There's a need to bridge the gap between science and industry, and that means we need to come to some determination that benefits both.”
2.2 Ballast Water Treatment Options
Ships use ballast water to provide stability and maneuverability during a voyage. Water is taken on at one port when cargo is unloaded and usually discharged at another port when the ship receive
Fuess & Davidenas
MH Systems, Inc.
Sotelo Jesus D.
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