Lafarge extends use of fan balancing system
9 Mar 2007
The new installations will take place during the Spring 2007 outages at the cement company’s locations in Cauldon, Hope and Aberthaw. Lord is to work with Lafarge to install and commission the systems in an effort to reduce unscheduled downtime due to high fan vibration.
Lafarge integrated the Lord balancing system into their operation at the
Dunbar Works in early 2006 after experiencing vibration problems and shut-downs linked to efforts to increase capacity the previous year.
A 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 50-mm 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 led to production losses amounting to 12,000 tonnes of clinker and nearly 100 hours of time. 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.”
The new balancing system features a permanently-mounted device to continuously monitor fan vibration levels and correct 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.
Since September, Lafarge had identified at least six scenarios when the balancing system was able to make a correction and avoid an unscheduled shutdown. As well as allowing the fan to run at extremely low vibration levels, it also keeps the plant from having to deal with unscheduled stops.
“The average vibration level is now 1.5 mm/second, which is the lowest it has ever been. We also have not had to make any further adjustments to the temperature and fan
speeds,” said Pepper.