Shaft generators help raise efficiency

01 Dec 2014
WE Drive, front side view

WE Drive, front side view

Finnish company WE Tech Solutions says that its direct drive shaft generators can help provide a useful gain in ship efficiency, by providing as much as around 800kW to the ship’s electrical system, avoiding the need to run auxiliary engines.

Man Yang 15.00

WE Tech has contracted with Wärtsilä Finland to deliver four direct drive permanent magnet shaft generator systems for a series of LNG fuelled tankers. The series of 15,000dwt product tankers has been ordered by Danish operator Terntank, to be built at Chinese shipyard Avic Dingheng Shipbuilding. The equipment delivery is due to commence in April, 2015.

According to WE Tech, Terntank aims to have the most energy efficient and environmentally adapted tankers. Using LNG as fuel will achieve significant environmental advantages, but the company claims that adding its WE Drive and the direct drive permanent magnet shaft generator technology to the mix, the energy efficiency of the machinery can reach levels that are “unprecedented in the marine industry”.

The WE Drive uses active front-end low harmonic drive technology, to allow the shaft generator to operate over the full main engine speed range, while generating electricity for the vessel’s electrical network at high efficiency over the entire range. This feature is particularly useful at electrical part loads – which WE Tech says is the normal electrical load condition in any ship.

In this case, the WE Drive and direct drive permanent magnet shaft generator in power take out (PTO) mode, will produce available power of up to 600kW for the vessel’s electrical network, generated by Wärtsilä’s fuel efficient two-stroke, low pressure, dual-fuel main engine. In this mode the auxiliary generators are not running. As the operating hours of the auxiliary generators are drastically reduced, significant savings can be achieved, while the reduced running hours decrease the need for maintenance.

Another current order for WE Tech comes from another Chinese yard, Zhejiang Ouhua Shipbuilding. This contract is for direct drive permanent magnet shaft generator systems for a series of 80,500dwt combination carrier ships (CABU vessels), ordered by Klaveness Shipping of Norway, with the systems to begin delivery at the end of 2015.

These installations are expected to generate up to 800kW from the WE Drive and shaft generators operating in PTO mode, from the ship’s fuel efficient two-stroke main engine, without running the auxiliaries.

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