Hanson Cement prevents emissions rules halting UK plant
23 Nov 2011
Clitheroe, UK – Hanson Cement has resolved an inherent design fault on the bearing assembly of a large centrifugal fan that could have halted production at its cement plant in Clitheroe, Lancashire, due to a failure to comply with dangerous emission regulations
The unreliability of the fan on a wet gas scrubber was preventing the plant from burning alternative fuels due to downtime on the gas cleaning system, forcing the plant to resort to more expensive fossil fuels. It was discovered that material build-up on the impeller caused increase vibration, which was damaging the non-drive end bearing and its housing, potentially resulting in its failure.
The design of the fan assembly meant the bearing was allowed to float within its housing, according to said David Holgate, engineering manager at Hanson Cement.
“In theory, this design has an internal clearance between the outer diameter of the bearing and the bore of the housing for expansion,” said Holgate. “But due to the imbalance of the fan impeller whilst in operation, the resulting vibration caused wear in the internal bore of the housing.”
The cement maker, engaged Brammer, a UK supplier of maintenance, repair and overhaul products and services, to provide engineering input, advice and a product application solution to allow operations to continue uninterrupted.
Brammer’s solution, which it developed with SKF, was to replace the non-drive end bearing with an SKF CARB toroidal roller bearing, as well as introducing a regular cleaning routine. No bearings or housings have needed to be replaced since the change, with an estimated cost saving of £15,000, the MRO company reported.
“Brammer’s solution was to install a fixed housing with a tight fit, with expansion taken care of through the internal design of the bearing itself,” said Holgate. “Previously we were cleaning the fan impeller on a weekly basis and changing the bearings around every six months. Since the retrofit, we have not had to replace the bearings.”
