environment
says Optimarin director Tore Andersen. “It saves DOF substantial time and cost in repeat negotiations but, most importantly, gives the company contractual certainty while creating a structure needed to measure and improve fleet- wide BWT performance.”
The Optimarin system is described as a standardised, highly modular solution with a small footprint that is easy to install. “These are key advantages when serving DOF’s retrofit demands, where some installations will be made during vessel operation or during extremely tight drydocking deadlines,” adds Tore Andersen.
The latest generation of another Norwegian system, OceanSaver, recently received DNV type approval certification. Previously focused on serving larger ships, OceanSaver is now also addressing the medium-sized tonnage sector with a Mark II system.
OceanSaver Mark II is described as a tailored
version of the already type-approved Mark I system but with most of its energy-demanding features removed. A higher performance filtration technology and considerably reduced piping are incorporated, while a lower installation time with less complexity will benefit both retrofit and newbuilding projects.
Cuts in procurement costs will be accompanied by lower life-cycle costs, taking into account spares, energy consumption and manpower requirements. The energy required by the complete Mark II system and related equipment is said to be 50 per cent less than that for the Mark I system. Cost effectiveness is enhanced by no treatment during de-ballasting. Mark II systems will be supplied to a pair of Suezmax tankers under construction at Bohai Shipbuilding in China and four bulk carriers building at the SPP Shipyard in Korea. The latter projects mark OceanSaver’s first installations in bulkers, each BWT system having a treatment capacity of 2 x 800 m3/h. A valuable reference was secured at end-2011
with the delivery of the 159,000 dwt Suezmax tanker Ottoman Integrity from a Korean yard for the Turkish owner Gungen Maritime & Trading. The OceanSaver Mark I system installation incorporates filtration, cavitation, disinfection and nitrogen super saturation. The filter and cavitation units are installed
in the pumproom, while the disinfection unit and nitrogen system are respectively arranged in the engineroom and casing area. Filtration of the sediment and biological material from the uptake water is achieved by fully automatic inorganic back-flushing filters. At the shipowner’s request, the filters were operated for over 70 hours during sea trials and reportedly performed according to specification and the full satisfaction of the owner, class, charterer and OceanSaver.
106 I Marine Propulsion I February/March 2012
valve open valve closed
filter
Wallenius AOT unit
piping system pump
sea chest
ballast tanks
Schematic of Alfa Laval’s PureBallast system during ballasting
“In order to get the best possible system for your type of vessel it is important to keep close co-operation with your selected maker all the way through the project from the early sales stage until the first cargo is on board,” Osman Gungen advises other operators.
“The nitrogen super saturation component offers potential for reduced vessel maintenance costs through improved corrosion performance of the inerted ballast tanks,” says Tor Atle Eiken, OceanSaver’s senior vice president, sales and marketing.
“It is particularly suited to
newbuildings and high-spec specialist vessels and is an optional item in the Mark II system.” The key features of the OceanSaver system are summarised as: large flow capacity capability; EX approval for gas hazardous areas; small footprint and high modularity (fostering flexibility in component location); and maintenance cost savings through reduced corrosion. Having successfully completed land-based testing of its BWT system, Desmi Ocean Guard of Denmark has proceeded with shipboard trials and expected full approval and certification by early 2012. The system exploits 40-micron filtration, low pressure UV radiation and the onboard generation of ozone for injection into the ballast water stream. Testing has been performed to IMO requirements with sea water of all salinities as well as fresh water. (Desmi believes it is the first UV system successfully tested with fresh water according to IMO requirements). As the treatment parameters for salt water and fresh water are very different, online monitoring of water salinity is performed and the treatment automatically adjusted. The power consumption fulfilled expectations, monitoring under real conditions showing less than 11 kWh per 100m3 of treated ballast water being required.
Aalborg-based Desmi Ocean Guard was established by the Danish companies AP Møller- Maersk, Desmi and Skjolstrup & Gronborg to
focus on developing systems to remove organisms from ballast water. Hyundai Heavy Industries
contests the
market with its EcoBallast system, which received type approval from the Korean government in March 2011. The system features a filter unit and a UV stage to remove and deactivate micro-organisms in the ballast water; chemical-free disinfection uses physicochemical inactivation by irradiation with ultraviolet light. A high-powered UV light from medium
pressure lamps ‘denatures’ the DNA of the organisms, preventing them from reproducing. The UV reactor was specially designed to deliver even flow distribution and maximise UV dosage with minimal pressure loss. Each system installation can be customised to the specific project. The Korean group also offers its HiBallast system, which received final approval last June. An electrochemical process disinfects organisms, the overall system comprising three stages: filtration to remove organisms larger than 50 microns; seawater electrolysis to produce and inject hypochlorite into the main ballast pipe during ballasting; and neutralisation to neutralise the ballast water during deballasting. HiBallast
is designed for container installation in
ships, bulk carriers and tankers, offering treatment flow capacities up to 8,000 m3/h. Installation is eased by a side-stream piping arrangement branched from the main ballast piping, which also facilitates retrofits in existing tonnage. Systems have been installed in container ships and bulkers. MP
www.mpropulsion.com
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