New thruster series introduced NORWAY
Privately-owned Brunvoll AS is in its fifth decade of designing and building thrusters at its production facilities near Molde, in western Norway, and lately has been actively developing its various thruster types. The company recently introduced a compact tunnel thruster series as well as a new compact gear box, and has made developments to its retractable thrusters. In addition, the company has reached the pilot project stage for its RIM-driven tunnel thruster. In 2006, the company, employing
some 170 people, also made extensive investments in its production plant, improving manufacturing with added capabilities for efficient un-manned machining.
In this article, Ship & Boat
International talks about the latest developments with Dr Knut Andresen, technical director and deputy managing director, at Brunvoll.
T
HE company has received its f irst orders for its recently-developed fourth
generation tunnel thruster for installation into offshore vessels. A number of new complementary power options are now available and the power range for these tunnel thrusters has also been extended, to over 3000kW. A new customised right-angle gearbox
series for Brunvoll's thrusters was also introduced last year, and has since proven very successful; the order backlog of this new type is now around 40 units. The right- angle gearbox can either be mounted onto its own bed frame, or, onto the steering gear of an azimuthing thruster of non-retractable type.
Brunvoll's new tunnel thruster series extends the power range to over 3000kW.
in 2006. According to Mr Andresen, the larger unit now installed differs much from the first prototypes. The elect r ical ly-dr iven f requency
conver ter-cont rol led RDT features permanent magnets in the rotor par t, which incorporates the propeller blades, and motor windings in the surrounding duct. ‘There is no propeller blade tip gap, and thanks to the hydrodynamically clean water f low, as there is no hub, cavitation is avoided which makes it very quiet and free of vibrations,’ he said. The prototype tests included also drive
system testing together with Norpropeller AS, a company in which Brunvoll is a shareholder, engaged in development of new types of elect r ic dr ives. The development work has been backed-up with comprehensive experimental data received from using computational f luid dynamics (CFD) design tools, directly integrated with the company's own 3D CAD/CAE tools. The CFD f low calculations can include
viscosity effects, turbulent f low and cavitation. The company is also testing an azimuthing 100kW prototype version of the RDT.
‘The new gearboxes can be used both for
tunnel thrusters and for further developed retractable azimuth thrusters with Z-drive. The benefits are lower overall height,’ noted Mr Andresen. A horizontally-mounted electrical motor can now also be used, which lowers height. In addition, the Z- drives can now be powered directly with a diesel engine.
Next step - testing full-size RIM- driven thrusters Brunvoll is also in the process of introducing its first full-scale pilot project RIM-driven thruster (RDT). The power of the thruster is 810kW, and it is being installed, as an extra third bow thruster, on a multi-purpose offshore platform supply vessel of type ST216, under construction for Østenjø Rederi at Astilleros Gondan SA, Spain. The vessel was due for delivery in May this year (S&B March/April 2007). This interesting diesel-electric 4100dwt
vessel will also receive Voith Schneider propulsion (2 x 2800kW) driven each by a 2500kW AC asynchronous motor. This newbuilding will be working for Shell UK on a five-year charter contract. A sistership order has also been placed at the Spanish yard. The other two tunnel thrusters forward
Brunvoll's diesel engine powered retractable azimuth thruster with a Z-drive, and new gearbox.
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will each have a power of 1400kW, and will also be resiliently mounted. ‘The resiliently mounted RDT unit really has potential of becoming a “whispering thruster”,’ Mr Andresen told Ship & Boat International. Various prototype configurations of the
100kW unit have been developed and tested since 2003, with the latest changes made
Cost efficient control systems Brunvoll has also recently introduced additional features of its thruster control, monitoring, and alarm systems, resulting in less expensive installation and new functionality. The improvements relate to reduced component costs and increased degree of integration of automation and monitoring systems onboard. ‘Cheaper broadband network comm-
unications via satellites has also made remote diagnostics possible,’ Mr Andresen said. ‘We are currently developing remote diagnostics of our onboard equipment. Of fshore operator s have typical ly established broadband connections between the office and f leet. Today this is primarily used for administrative purposes, but it can easily be extended for remote monitoring of our thrusters.’ Mr Andresen noted that the remote
monitoring and trouble-shooting tasks can easily be handled by a service sub-contactor
Brunvoll's 810kW RIM-Driven thruster is installed on a multi-purpose platform service vessel due for delivery in May this year. It is also the first such vessel such offshore vessel with Voith Schneider propulsion.
SHIP & BOAT INTERNATIONAL MAY/JUNE 2007
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