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Bearings a key component in supply of green energy for Beijing’s Olympic Games

Beijing, China -- When the leading Chinese wind turbine company Goldwind was awarded the contract to supply 33 turb...


Beijing, China — When the leading Chinese wind turbine company Goldwind was awarded the contract to supply 33 turbines for the 2008 Beijing Olympic Games, the company selected SKF as the bearing supplier for this prestigious project.

The 1.5 MW turbines are Goldwind’s largest turbines and, like all OEM’s, Goldwind knew that the larger the turbine the more they need to be sure about the reliability of critical components like bearings. That is because turbines producing higher energy outputs are usually physically bigger and taller than smaller energy-producing units. And that results in more wind being captured, which leads to higher forces on machinery at the top of the turbine where the electricity is generated,. In the case of Goldwind’s 1.5 MW turbines, that is 65 metres from the ground.

In choosing SKF, the Goldwind company based its decision on a good history of co-operation with SKF on smaller turbines, but also the fact that SKF had supplied bearings for many bigger turbines around the world, including the biggest in the world at that time; Repower’s 5 MW turbine that was designed for the extremely tough environment of offshore wind energy generation.

Mrs. Qiaozhen Ning, director of mechanical design at Goldwind, said “we are very happy to select SKF for this project because we know from experience that they understand the application demands of wind turbines, and the technical support we get from the engineers in SKF China is excellent.”

The 1.5 MW design is a direct drive turbine requiring no gearbox, but the turbine mainshaft — to which the blades and rotor are connected — must be supported by bearings to allow the blades and rotor to rotate in order to produce electricity.

One major concern for all turbine builders is the ever-changing wind conditions in terms of continuity, strength, direction and water content (rain). Such conditions mean that the forces transmitted from the wind through to the actual turbine generator are continually changing. Critical components, like bearings, have to be able to withstand a broad range of forces that are continually changing; in magnitude and direction, and also have to be resistant to, or protected from, rain in order to run reliably according to design and application expectations.

Such conditions are the main reason why wind turbine applications are considered one of the most demanding for bearings. Bearings are precision components that are designed for specific ranges of speed, forces, angular misalignment, etc., and their ability run reliably in such conditions calls for excellent design and manufacturing quality.

While almost all machinery is expected to have some form of ‘running attention’ and maintenance, unexpected stoppages in wind turbines can be extremely expensive because usually cranes have to be hired for several days to dismantle and repair the turbine. And of course, the turbine is not producing electricity while under repair. So reliability of critical components is a very high priority for turbine designers, builders and users.

The bearings selected for the 1.5 MW turbines are a single-row cylindrical bearing, almost 1 metre outside diameter, and a double-row tapered roller bearing, almost 600 mm outside diameter.

SKF calculations show that both bearings have sufficient capacity and design features to operate reliably in the expected range of weather conditions to be encountered during the Games but also for many years after the Games are finished, when the electricity generated will supply ‘green’ power to the city of Beijing. The turbines are all erected and many are already producing power.

Since the contract was awarded to Goldwind another 10 turbines have been ordered. The 43 turbines now constitute a wind farm on the banks of the Guanting reservoir in Beijing. These turbines are part of the increasing use of wind power in China and will probably be seen by millions around the world as television reports of the Olympic rowing event, that takes place on the Guanting reservoir, are broadcast in August 2008.

For further information, visit www.skf.com. Article supplied by Minett Media.