Kiln Shell ovality
Kiln shell ovality is an important parameter to assess kiln health and the monitoring become mandatory, if avoided recurring refractory problem observed. And, in extreme case crack on kiln shell / tyre is anticipated. Principally, Ovality is defined as difference of shell diameter in horizontal and vertical axis. The difference arises because of flexing in kiln shell during operation, parameters like thermal, material loading, etc in the shell.
The shell flexing is governed by following factors:
- Beam Strength of Tyre
- Kiln Shell Thickness
- Kiln shell and tyre temperatures
- Kiln Shell Misalignment
- Air gap between tyre ID & chairpad OD
- Thermal and material loading
- High run-out of kiln shell close to support stations, etc
Variation in any of above factors influence shell ovality and has a detrimental effect upon the exceedance. Higher ovality has influence over refractory failure nearby tyre section and undue stress on kiln shell and tyre section. If higher stresses are allowed for extended period premature failure of mechanical element (shell / tyre) may result.
Ideally, ovality is proportional to airgap or the tyre migration at a pier. And regular inspection is important to take suitable action at nick of time, before is become too late.