Södra Cell Värö is one of Sweden’s largest pulp mills with a production rate of 700,000 tons of pulp per year. The pulp mill is in operation 24/7 all year and unplanned downtime has major economic consequences.

For many years, SPM has supplied them with over thirty online vibration monitoring systems as well as two portable vibration measurement systems of the Leonova Diamond.

Following detection of a crack in a gear on the output shaft on a rotary kiln an online system was installed to monitor the bearing and gear condition of the gearboxes The rotary calciner is production-critical therefore a breakdown of the gearboxes on the kiln would lead to significant costs for secondary mechanical damages.

The measurements showed a sharply increasing trend at the measuring point on the gearbox output shaft. At the same time, no fault symptoms were consistent with the gearbox’s internal gears or bearings. The damage frequency was 21X, which coincides with the cogs on the gear mounted on the output shaft. Initially, damage to the gear in question was considered unlikely. Instead, it was assumed that the rising shock pulse levels were caused by problems in the gearbox; this was due to the sound that could be heard while the gearbox was run at low speed and which seemed to propagate through the gearbox itself to a large degree. The gearbox was, therefore, disassembled, but no damage was detected. The crack in the gear (with 21 teeth) was discovered as it was being heated before re-mounting on the output shaft following the re-assembly of the gearbox. The heat made the crack visible and also caused the oil/grease in the crack to seep out.

The monitoring system consists of four shock pulse transducers (44000) and one vibration transducer (SLD144) on each gearbox. There are also two vibration transducers (SLD144) on each motor. All transducers are connected to the Intellinova Compact (INS18) online system.

The mechanical condition of the gearboxes is monitored using the SPM HD measurement technology, which is very well suited for this low-RPM application.

In the spring of 2020, new, larger gearboxes were installed. In conjunction with this change, the gear ratio also changed, as did the gear on the output shaft which was changed to another dimension. At the same time, the monitoring system was changed from Intellinova Compact to Intellinova Parallel EN with sixteen channels, which makes it possible to make optimal use of measurements with time-synchronous averaging.

To discuss your monitoring requirements within hazardous areas, get in contact with an SPM Instrument engineer today by
telephoning: +44 1706 835 331
or visit: www.spminstrument.com