Feature 1 | BALLAST WATER SYSTEMS N.E.I. takes a unique approach with VOS
US-based N.E.I. Treatment Systems is preparing to complete a number of retrofit orders.
N
.E.I., which is marketing its Venturi Oxygen Stripping (VOS) ballast water treatment system (BWTS) as
a solution for larger vessels in particular, has relatively little recent experience of retrofits, although it has secured orders for newbuild VLCCs in South Korea and China. However, it has in the past installed several
trial systems onboard container and bulk vessels, using riding squads. Tese 1000m3
/
hr systems were installed without having to move existing equipment, and successfully treated ballast water. Building on that experience the company
now has several pending larger scale, permanent retrofit orders and expects this type of work will be a key part of its business in future, peaking between 2014 and 2019. Giles Candy, director global sales, says: “Te IMO Ballast Water Convention, and pending US regulations, define a retrofit schedule for the entire world fleet. Te high demand for retrofits in those six years is a growing topic of discussion and there will be pressure to extend the deadlines.” However the IMO Convention cannot
be changed before it is ratified and Candy points out: “If it is not ratified before the end of 2012 retrofit numbers will be further increased as newbuilds launched without BWTS attempt to install within 12 months of the ratification date.” Te design of VOS makes it appropriate
as a retrofit option, as it avoids the need for filters or other components close to the ballast pumps and, through using existing electrical panels, more flexible installation options can be offered, a big advantage when engineering a system into an existing ship. Candy notes: “VOS does require deck piping, but it does not require filters or treatment equipment to be installed in the busy space around the ballast pumps. Te location of the stripping gas generator is flexible inside the machinery space, and the Venturi Injectors are intrinsically safe, so they can be installed in a pump room or on the deck of a tanker. VOS uses little electrical power so generator and electrical panels do not have to be upgraded and there is no requirement
24
A VOS Venturi Injector installed as a retrofit on a 5500TEU containership.
for chemical storage. These factors make installing VOS relatively simple particularly for larger systems.” N.E.I also claims VOS is unique in the
BWTS market because it brings the added benefit of corrosion protection to the vessel. Candy says: “Corrosion accelerates over time so an older vessel, particularly without PSPC standard coatings, will see a quicker and larger return, in terms of extended coating, anode and steel life, reduced ballast tank maintenance costs and increased charter availability. Tis will help owners offset what will be a significant investment in a BWTS, and no other system can offer such a return to an owner.”
Te VOS system works by depriving aquatic
organisms of the oxygen they need to survive, inducing a low-oxygen, or hypoxic condition in the ballast tanks using an inert gas. Tis low-oxygen environment also limits the amount of oxygen available to form iron oxide, or rust, thereby protecting the internal steel surfaces of the ballast tank against corrosion and preventing premature deterioration of ballast tank coatings. In less than 10 seconds, N.E.I.’s patented VOS System removes 95% of dissolved oxygen from ballast water by mixing very low-oxygen inert gas with natural water as it is drawn into the ship as ballast. In a process similar to evaporation, the inert gas then strips the water of its dissolved oxygen. SCRT
Shiprepair and Conversion Technology 1st Quarter 2012
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