Fan balancer cuts downtime

A TEVA product story

Edited by the Engineeringtalk editorial team Feb 26, 2007

Following the successful installation of a Lafarge UK has opted to install Lord fan balancing system at three more of its sites in the United Kingdom.

Following the successful installation of a Lord fan balancing system on the preheater ID fan at the Lafarge Dunbar Works in Scotland, Lafarge UK has opted to install the system at three additional sites in the United Kingdom.

Orders have been placed for installation during the Spring 2007 outages at the Cauldon, Hope and Aberthaw locations.

Lord Corporation, in partnership with their UK distributor, TEVA, will work with Lafarge to install and commission these systems in an effort to reduce unscheduled downtime due to high fan vibration.

Lafarge integrated the Lord balancing system into its operation at the Dunbar Works early in 2006 after experiencing vibration problems and unscheduled shut downs that resulted from efforts to increase capacity the previous year.

An unexpected side effect of the capacity modifications was a severe material build up and associated excessive vibration levels on the preheater ID fan.

The result was build up on the fan blades up to 50mm thick, forcing Lafarge to make several unscheduled shut downs for cleaning of the rotor.

Four forced shutdowns caused by fan vibration and build-up in 2005 certainly caught Lafarge by surprise.

Production losses amounted to 12,000 tonnes of clinker and nearly 100 hours were lost.

Furthermore, the outer edges of the fan blades were wearing, and the excessive vibration caused a failure in the motor's white metal bearings.

"We made the production changes to increase the level of output", said David Pepper, Maintenance Manager at Lafarge Dunbar.

"However, there were also some negative effects".

"Reversing the changes would have taken us right back where we started, losing valuable time and profits".

After analysing the balancing system specifications, Lafarge chose to install Lord's fan balancing system during its Spring 2006 outage.

Lord developed a balancing system comprised of a permanently mounted device that continuously monitors fan vibration levels and corrects for unbalance while the fan is running.

The system is set up to monitor fan bearing vibration levels and the vibration phase angle in order to automatically correct for unbalanced conditions.

This is done while the fan is running at operating speed, eliminating costly downtime to clean and manually balance the fan.

Once levels reach a pre-set high trip point, the system switches on, commanding balance mass inside the shaft-mounted system to adjust as needed to counteract the unbalance and reduce the vibration.

Typical balance cycle times range from 30 to 120 seconds, depending on operating speed.

Because of the integration of Lord's balancing system, shutdowns from excessive vibration are a thing of the past.

As of September, Lafarge had identified at least six scenarios when the balancing system was able to make a correction and avoid an unscheduled shutdown.

The balancing system not only allows the fan to run at extremely low vibration levels but it also keeps the plant from having to deal with unscheduled stops.

For Lafarge, what is equally as important as the reduction of downtime is that it is able to continue to increase their output.

"We are very happy with the results", Pepper said.

"The average vibration level is now 1.5mm/second, which is the lowest it has ever been".

"We also haven't had to make any further adjustments to the temperature and fan speeds".