Rotary Kiln shell temperatures

News Date:2016-04-22 16:03:50

Many rotary kilns drying today have thermal cameras mounted to monitor the kiln shell for bricking purposes. Monitoring the rotary  kilns shell temperatures is important because it indicates what is occurring with the refractory brick but it also affects mechanical conditions of other components. The rotary  kilns  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. For example, for a cooler rotary  kilns shell there will be more creep than a hotter rotary  kilns shell. If there is more creep, there will be more clearance between the tyre and the shell, which will increase the kiln shell ovality. These are conditions the maintenance and production personnel need to be aware of in their daily operations.

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 rotary  kilns. 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 rotary  kilns 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.

Another area to check on a weekly basis is the condition of the tyres, support rollers and retaining blocks/stop blocks on each pier of the kiln. Wear patterns will sometimes develop on the surfaces of tyres and support rollers and can be an early warning sign of possible mechanical conditions on the kiln. Dark colouration across the face of a support roller is an indication of excessive thrust of this support roller. When a support roller has very little individual thrust as a result of how it is adjusted, it will normally have a bright shine to the face of the roller. When a roller has a very dark face across the wearing surface, it is an indication of excessive thrust on this roller.

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.