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1. KILN MIGRATION
Presented By: Faisal Nadeem
Trainee Engineer

2. KILN MIGRATION
It is relative moment between the kiln shell and kiln tire
Also defined as rotational difference between kiln shell and kiln tire
Migration indicates the gap between kiln shell and the kiln tire
Higher or lower values rather than recommended range of migration is
dangerous

3. KILN MIGRATION
Kiln Shell Outer diameter is always smaller than the inner diameter of Tire
Due to this circumference difference, kiln tire rotates slower as compared to
kiln shell
Difference in the linear movement, of the both surfaces, can be observed in
each revolution of kiln.
Allowable migration is normally 6 mm to 8 mm

4. KILN MIGRATION

5. KILN MIGRATION

6. CALCULATION OF MIGRATION
Migration can be calculated by marking 2 lines, coinciding each other on kiln
tire and shell
Observe both lines after one revolution
To get accurate results, observe both lines after 10 revolutions
Then divide migration value (mm) by 10 (revolutions)
So, migration per revolution can be easily be calculated

7. How to get Migration back in Limit?
Find the Hot Air Gap
• 𝐴𝑖𝑟 𝐺𝑎𝑝 =
𝑀𝑖𝑔𝑟𝑎𝑡𝑖𝑜𝑛 𝑉𝑎𝑙𝑢𝑒 (𝑚𝑚)
𝑃𝑖 (3.14)
Allowable hot air gap is 3mm to 4mm
Find the Shim Thickness which need to be placed between shell and tire
• Sℎ𝑖𝑚 𝑇ℎ𝑖𝑐𝑘𝑛𝑒𝑠𝑠 =
𝐶𝑎𝑙𝑐𝑢𝑙𝑎𝑡𝑒𝑑 𝐴𝑖𝑟 𝐺𝑎𝑝−𝑅𝑒𝑐𝑜𝑚𝑚𝑒𝑛𝑑𝑒𝑑 𝐴𝑖𝑟 𝐺𝑎𝑝
2

8. How to get Migration back in Limit?
Example: If the kiln is running with migration/rev of 36mm.
• 𝐴𝑖𝑟 𝐺𝑎𝑝 =
36
3.14
= 11.5
• Sℎ𝑖𝑚 𝑇ℎ𝑖𝑐𝑘𝑛𝑒𝑠𝑠 =
11.5−3
2
= 4.25 𝑚𝑚
• So, the required shim thickness is 4 mm

9. THANKYOU.
.