March 29, 2004
Ballast water system wins INTERTANKO challenge
INTERTANKO, the International Association of Independent Tanker Owners, has announced the winner of its Environmental Challenge.
The winning entry--NEI Treatments Systems' Venturi Oxygen Stripping Ballast Water Treatment System--was selected by the panel of judges from three entries short-listed by INTERTANKO's Environmental Committee. The other short-listed entries were Teekay Shipping (Japan) Ltd with its Natural Ballast Water Exchange and Dr Timothy Gunner and Bjarne Thygesen with their VOCON Procedure.
NEI Treatment Systems' Venturi Oxygen Stripping System, says INTERTANKO, "offers a safe, reliable, cost-effective ballast water treatment system for ocean-going vessels."
The system is said to eliminate the introduction of invasive organisms while simultaneously protecting the vessel's ballast tanks against corrosion. By mixing very low-oxygen inert gas into ballast water as it moves through the ballast system, the system removes 95% of the dissolved oxygen from the water in seconds, with no flow rate limit, leaving it to arrive in the ballast tanks in a deoxygenated state. Harmful aquatic organisms are suffocated within hours. Despite its technological complexity, says INTERTANKO, the system is mechanically simple and will be no more time-consuming to operate than existing ballast management systems.
INTERTANKO notes that the concept has been introduced at a time when regulators and ship operators are looking for effective and practical ballast water treatment systems to enable their vessels to comply with upcoming IMO ballast water regulations.
"Laboratory and pilot-scale biological testing indicate that this treatment results in the discharge of ballast water that will meet IMO standards," says NEI's President Peter McNulty, responding to industry concerns that there might not be a shipboard-ready technology available to meet IMO deadlines. A twelve month corrosion test will be completed next month. Preliminary results indicate up to 80% lower corrosion in test panels.
The Natural Ballast Water Exchange submitted by Teekay Shipping (Japan) is a new method for exchanging ballast water requiring no power. The system relies entirely on natural flow and gravity forces to replace 95% of a ship's ballast water in a considerably reduced time compared to methods currently used. It takes clean water from an inlet in the vessel's bow, utilizing the pressure differential along the hull surface of a running ship. It leads the clean water into the water ballast tanks through the main water ballast line, using positive pressure to push out tainted water. The tainted water is removed from the ship through the sea chest by using the negative pressure/suction existing at the bottom of the hull surface of a running ship. Ship power is only required at the final topping-up stage of the ballast exchange operation.
The other short-listed entry, the VOCON Procedure, achieves an 80% reduction in volatile organic compound (VOC) emissions from the transportation of crude oil in tankers by a straightforward operational procedure, thereby controlling atmospheric pollution and reducing cargo loss. No additional equipment is required. When gas pressure is routinely released from the vessel's cargo tanks during the laden voyage, current practice does not make it clear when the release should be stopped. The VOCON Procedure allows for the different physical behavior of the two distinct types of gas present in the ullage spaces of a laden and inerted cargo tank--unsaturated gas from the vessel's inert gas system, and saturated hydrocarbon vapors from the crude oil cargo. The procedure requires the monitoring and recording of the pressure drop during the routine gas release. After the initial fast pressure drop, then as soon as the rate of pressure drop eases off and becomes constant, the gas release is stopped.
The Environmental Challenge was set up to find cost-effective, practical solutions to a number of major environmental issues and concerns related to the transport of oil in ships.