Shutdown

The most important part of shutdown procedure – always make notes before, during and after a shutdown especially the problems area. The kiln components may be cool, the condition around can changed, so it may be difficult to determine the correct adjustment. Having data (notes, logs) as a reference all corrections, alignments and replacement can be more precise and the work can be accomplished accurately.

The example of notes that can be prepared:

  • Check the tires and rollers running surfaces condition. Everything should be smooth and shiny. If not – some improvement job should be planned.
  • Control axial position of each tire. Analyze if you need any repositioning.
  • Monitor and note the date about chair pads and welds condition. Maybe some of them are missing. Look for loose bolts and cracked welds. Try to find the reason of damages.
  • Control any unusual noises and write down the data.
  • Check what is the gear/pinion axial position.
  • Measure the root clearance.
  • Note the thrust roller position etc.

By reburial monitoring of rotary kiln components preventive maintenance becomes a normal habit of everyday operation. Advantage?? – cost efficiency will increase a lot.

Lubrication

There are a very controversial question – Does the migrating tire and its components (chair pads, retaining blocks) should be lubricated? The answer may seen to be simple as the lubricating of running parts is a natural requirement of proper operation. But some experts advice opposite. On the one hand argument is that the grease attract dust, dirt and increase wearing process. The second opinion – lubrication will improve slippage and reduce wear.

The answer is slippage will be present with or without grease. Also any dust or dirt will consumed by the grinding action – no effect on metal consumption.

Generally shell rolls inside the tire but 100% rolling action is not possible due to for example a changing condition. The lubrication between tire and shell is not to increase slippage but to protect local area  where metal failure appears.

During operation with lubrication between shell and tire higher value of relative movement can be observed (compared to creep without lubrication).  The surfaces is polished. Anyway this situation is more desirable than tire migration which is limited. Inhibited creep will eventually increase the wear.

When the metal slides by another metal we are in risk of “galling”. It appears when two surfaces attach and destroy themselves (on microscopic level). As a final effect some “spitzers” are created, especially at the side of the tire – on retaining blocks contact area.  In these case lubrication is very useful and will decrease meal consumption.

For these kind of application the graphite is recommended. Other lubricant that can be used should contain copper, aluminum, molybdenum etc. The “grease” should not be used.