When checking the temperatures of cement rotary kiln spare parts gear ring, record the direction of thrust of each individual support roller. For example, is the roller shaft in the downhill direction and thrusting the kiln uphill, or is it in the uphill direction and thrusting the kiln downhill? The direction of the roller shaft can be determined by sounding end caps on some kilns, while other kilns will require opening a view port to see the direction of the shaft. The maintenance staff can demonstrate how to find the direction of thrust. The reason why checking the direction of the support roller shafts is important is to aid the maintenance staff in knowing which roller needs to be moved if there is excessive axial thrust of the kiln. Also, if there are signs of hot bearings on a support roller it is important to know the direction of thrust of the roller shaft.

　　1.Kiln shell temperatures

　　Many cement rotary kilns today have thermal cameras mounted to monitor the kiln shell for bricking purposes. Monitoring the shell temperatures is important because it indicates what is occurring with the refractory brick but it also affects mechanical conditions of other components. The kiln will respond differently to hotter or colder shells in how it will axially thrust against the thrust roller. It also affects shell ovality and creep readings.

　　2.Weekly inspections

　　Weekly inspections are mostly a review of what has been happening with conditions such as the axial thrust of the kiln, the shell temperature, bearing temperatures and the general conditions of the kiln. One item that needs to be recorded on a minimum of a weekly basis is the creep of the tyres. Creep is the relative movement of the tyre versus the kiln shell. Because the tyre ID is larger than the diameter of the kiln shell (and support pads), the tyre does not migrate the same distance circumferentially as the shell. This difference in movement is referred to as tyre creep.

　　One of the most common wear problems on the majority of kilns is the thrusting of the tyre against the retaining/stop blocks holding the tyre in place. This condition is the result of misalignment present between the shell and the tyre, the tyre and the roller, and/or the structural base of the pier top. In some cases it can be a combination of these three components. When this type of condition exists, it is important to monitor the wear rate of the retainer/stops to determine if the misalignment is excessive.

　　3.Miscellaneous

　　Always monitor any subtle changes that may occur to the kiln over an extended period of time. These can be simple things, such as vibration, which may be an indication of something that has changed in the drive train. Unusual patterns on the wear faces of the kiln tyres and rollers are also an indication of mechanical changes. Oil leaking onto the surfaces of the support rollers as a result of over filling the bearing housings will cause changes in the axial thrust of the kiln. All of these little things will indicate different problems and by monitoring these conditions we will have a better handle on when to take action and when not to take action.

　　4.Conclusion

　　When one studies the effects of reliability and the impact it has on operational efficiencies, one unplanned outage can significantly change the overall efficiency of a plant. The surest and most cost effective way to avoid unplanned outages is to monitor the equipment, trending conditions with the approach of implementing risk analysis to determine if a planned outage for a short duration outweighs the risk of an unplanned outage with potentially much longer production losses.

　　In today’s environment with a shortage of skilled labour to staff maintenance positions, cross-training of non-maintenance personnel is a means of achieving goals without further burdening a depleted maintenance staff.