Feature 4 | DIESEL-ELECTRIC AND ELECTRIC PROPULSION Podded power-up
Armed with a long-term investment and business plan, Sharjah-based Ship Power aspires to become a recognised brand for electric propulsion, using podded motors.
K
een to establish an alternative to traditional diesel engine set-ups, the design philosophy of Sharjah,
UAE-based engine manufacturer Ship Power revolves around modular electric motor pods suited to applications such as tunnel thrusters, retractable azimuthing thrusters and main azimuthing propulsion units up to 1000kW. According to the company, the power pod concept from Ship Power offers operational and environmental benefits over existing thrusters for manoeuvring and propulsion duties. In addition, production and maintenance advantages derive from simplicity of construction and installation, and from common applicability to different types of propulsion systems.
ABB debuts Onboard DC Grid
A diesel-electric offshore service vessel ordered from Kleven Maritime’s yard in western Norway will provide the debut reference for a new direct current(DC) power system developed by ABB. Known as the Onboard DC Grid, the concept has been purpose-designed for vessels with low-voltage power systems, including tugs, ferries, offshore support vessels and yachts. Through the innovative use and integration of existing components, it promises efficiencies in power distribution and electric propulsion, dispensing with the need for certain equipment and sources of inefficiency attributed to alternating current (AC) systems. The initial recipient will be a 94m platform support ship newbuild contracted
by Norwegian owner Myklebusthaug Management, and due to be delivered by Kleven’s Ulsteinvik yard during the first quarter of 2013. ABB claims that a key advantage of Onboard DC Grid is the fact that the ship’s engines do not have to be run at a constant speed, but can be operated so as to optimise fuel consumption at each load level. This should prove especially beneficial for offshore vessels in dynamic positioning (DP) mode, where average electric thruster loads are normally low but where, for safety reasons, the number of engines running is high.
Moreover, by eliminating the need for propulsion transformers and main AC switchboards, the electrical equipment footprint in a vessel can be decreased by as much as 30%. The more flexible power and propulsion system is claimed to cut fuel consumption and associated emissions by up to 20%. ABB’s Onboard DC Grid connects all DC links and distributes the power through a single main DC circuit. It incorporates products such AC generators, inverter modules and AC motors, but eliminates the main AC switchgear and transformers.
32 Fed by electrical energy from the
shipboard power plant, the motor within the pod nacelle is controlled by variable frequency drive, turning the unit’s propeller mounted directly on the motor shaft. Te system provides full nominal torque, smooth and stepless power delivery and thrust control in either direction over the entire running speed range, enhancing manoeuvrability. The company’s developing portfolio
includes a series of tunnel thrusters based on the electric power pod design, and covering unit power needs in the 150-1000kW range. All are driven using the same method, albeit with different voltage set-ups. Each incorporates a fixed pitch propeller, which
can be optimised to the hydrodynamics and precise requirements of every project.
Reduced emissions An all-electric system embracing thrusters of this type dispenses with the need for additional power units, leading to reduced emissions, argues Ship Power. Environmental attributes of the concept are also represented in lessened noise and vibration levels. Te elimination of mechanical transmission losses makes for improved efficiency and reliability, while the eradication of a motor or drive train in the thruster room gives space savings and more ship design flexibility. Te state-of-the-art variable frequency drive
for the pod motor can be positioned in various locations, be it the thruster room, engine control room or separate compartment. Te drive is fully-programmable for ultra-smooth operation and infinitely controllable thrust in either direction. Ship Power has paid particular attention
to construction and durability, as regards all motor pod and structural elements, so as to withstand extreme stresses in offshore conditions. Te robust tunnels incorporate stiffening rings to prevent welding distortions, and the tunnel
structure
houses a stainless steel liner in the propeller running area to reduce wear and tear. Te complete thruster can be mounted or demounted in the tunnel, facilitating rapid change-out of the pod unit in drydock. It is envisaged that service exchange units will be available in the future. Manufacture of the different elements
is geographically split, with controls and automation, motor casings and machined parts, and tunnels and structures entrusted to companies in the UAE, and other parts and seals being sourced internationally, with the motor stator and rotor produced in the US. Assembly and testing has to date been carried out at Flanders Electric in the US, and Ship Power is targeting assembly and production of the first units in the UAE within the first quarter of 2012. SBI
Ship & Boat International January/February 2012
Page 1 |
Page 2 |
Page 3 |
Page 4 |
Page 5 |
Page 6 |
Page 7 |
Page 8 |
Page 9 |
Page 10 |
Page 11 |
Page 12 |
Page 13 |
Page 14 |
Page 15 |
Page 16 |
Page 17 |
Page 18 |
Page 19 |
Page 20 |
Page 21 |
Page 22 |
Page 23 |
Page 24 |
Page 25 |
Page 26 |
Page 27 |
Page 28 |
Page 29 |
Page 30 |
Page 31 |
Page 32 |
Page 33 |
Page 34 |
Page 35 |
Page 36