OPERATION & MAINTENANCE OF POWER PLANTS
Smart bearing solution saves over €130,000 at energy plant
industrial fan units, the plant requested the services of NSK to propose and implement a suitable solution. After performing an application review as part of NSK’s added value programme (AIP), a change of bearing and fi xing arrangement led to considerable cost savings. T e two direct-drive overhung fans,
W
which are supported by spherical roller bearings in plummer blocks, operate 24/7.
BEARING UP
hen a UK-based electricity producer was experiencing frequent breakdowns due to bearing failures in two
Spherical roller bearings use advanced materials that make them suitable for high speeds and loads
As primary total air fans, their role is to feed air to the boiler at a rate of 8 m3
/
second with an output pressure of 13kPa. However, the bearings in each unit were failing every three months on average, a
situation that would take three engineers 10 hours to remedy each time, incurring high costs per breakdown. T e long time and high cost of
replacement was largely due to the size of the task. Each fan is around 3.5m in diameter and attached to the end of a 2m long, 135mm diameter shaft. Shaft rotation is 1,487rpm, powered by a directly coupled 350kW electric motor. “Condition monitoring was being
The application review attributed the root cause of industrial fan unit failure to incorrect bearing arrangement
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performed by the plant on both bearing units for each fan,” explains Dennis Briggs-Price from NSK. “Temperature would be monitored continuously by a magnetic probe, with weekly vibration checks performed on each bearing, measuring velocity in a radial position [vertical]. Normal condition readings would be around 70°C, with a velocity of 5mm/s. Every time these values were signifi cantly exceeded, the bearings would be replaced by the plant as a precautionary measure as imminent failure was perceived. Typical values achieved before replacement would be 90-100°C
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