Ballast water ozone injection method and system

#The invention relates to a ballast water ozone injection method and system. More particularly, the invention relates to a system for using ozone to treat ballast water during loading or discharge of ballast water to or from the ballast tanks of a sea faring vessel.

#Ballast water weight is used by sea vessels to compensate for a lack of cargo weight when the cargo load is empty or partially empty. For example in a typical transport operation, a sea vessel docks at a first port where it is loaded with a cargo that the vessel transports to a second port where the cargo is unloaded. The vessel then returns to the first port where it is loaded with another cargo. Typically, the vessel travels empty from the second port back to the first port to pick up another cargo. The vessel is equipped with ballast tanks that can be filled with water to maintain the balance of the vessel on an even keel when it travels empty. Conventional ballast tanks include valves usually mounted over apertures through tank bulkheads. The valves are actuated to move water between and into and out of various ballast tanks to trim the vessel when empty of cargo or when carrying an unevenly distributed cargo.

#The vessel fills its ballast tanks by taking on sea water, usually at its cargo discharge port. The sea water is charged into the ballast tanks at the same time that the vessel off loads its cargo. The vessel then travels to its cargo loading port where it takes on cargo while at the same time it empties at least some and typically all of its ballast tanks by discharging the ballast water into the loading port water environment.

#FIG. 1 is a schematic perspective view of a double hulled tanker and a prior art ballast water treatment system;

#FIG. 2 is a schematic top view of a prior art tanker and treatment system;

#FIG. 3 is a schematic side view of a prior art tanker and treatment system;

#Ozone (O3) is an allotropic form of oxygen. It is an unstable blue gas with a pungent odor, a molecular weight of 48 g/mol and a density as a gas of 2.154 g/liter at 0° and 1 atm. It is approximately 13 times more soluble in water than is oxygen. Ozone is highly unstable and is a powerful oxidizing agent. It is 1.5 times better and approximately 3125 times faster than chlorine as an oxidizer. It is non-persistent and has a very short half-life. Its half-life in pure distilled water is approximately 40 min at pH 7.6. Because of the unstable nature of the O3 molecule, it cannot be stored but must be generated on-site.

#Typically, ozone is produced by passing oxygen, in some concentration, through a highly charged corona field, a technique known as “corona discharge”. The corona may be produced by applying a very high electric potential (20 kV) between two conductors that are separated by an insulating dielectric layer and a small air gap. Under these conditions, molecular oxygen (O2) passing through the gap between the conductors experiences sufficient dissociation energy to partially ionize. A certain fraction of the free oxygen ions will re-associate in the form of O3, according to the equilibrium reaction equation:

#3O2+69 kcal⇄2O3  (I)