The Operational Hot kiln axis is measured in vertical and horizontal plane using the most precise methods. This is important to establish and minimize the stresses on the kiln shell, uneven loads between the supports and the supporting components. Especially this is also very much important for maximizing refractory life and coating stability as the shell flexing would be high if the misalignment exists.
Every kiln shell undergoes flexing during normal rotation of the kiln, however the extent of shell flexing depends on various reasons like high diametrical difference between the tyre ID and kiln shell OD, major kiln axis misalignment, bend in the kiln shell etc. This will influence the life of the refractory.
To establish the actual flexing of the kiln shell during normal operation we use high resolution Shell Flex Beam with which we can establish and explore the possible reasons for high flexing of the kiln shell, if any.
Every running kiln exhibits some amount of bend (runout) either it could be existing from the fabrication or while assembling of shell during erection. Also, there could be a temporary bend (Thermal Bend) caused by kiln shell temperature variation around the circumference at any location along the length of the kiln which is normally caused due to uneven product coating or refractory thickness variation inside the kiln. Based on the vicinity of the bend existing in kiln shell, it will contribute to cyclic load on the drive, supporting components and improper sealing at the inlet or outlet ends of the kiln.
Hence it is very much important to study the shell profile (runout) condition of the kiln and the same being carried out by us with non-contact laser along with corresponding temperatures of the kiln shell.
The above kiln shell bend if it is at the vicinity of the supports (tyres) will cause cyclic load on the support roller in turn leading to cranking or deflection of the support roller shaft. If the same is beyond the tolerable limit, it can cause failure of the shaft.
The same is measured with non-contact laser equipment to establish extent of deflection of support roller shaft.
Excessive or improper skew of the rollers will lead to abnormal floating of the kiln, uneven wear of tyre and rollers working faces. Also this leads to excessive loads on thrust roller and thrust bearings.
The same will be corrected while making the support roller adjustments to correct the kiln axis.
The spot mechanical inspection of the kiln girth gear and pinion will be carried out to provide vital information for proactive maintenance purposes. Such as Axial and Radial run-out of gear (evaluated along with root clearance), gear & pinion lubrication condition and temperature profile of the teeth.
Note: Access to the girth gear and pinion is often restricted and a detailed evaluation is requiring a kiln stop during analysis. If this is not possible only visual estimates can be made.
Indicative information such as base plate slope, diameters and positions of tyres are critical elements in determination of the general mechanical condition. Walk-by and detailed visual inspection of critical components of the kiln provide vital knowledge and information about the kiln. Based on these findings recommendations shall be provided for reliable operation of the kiln.
We prepare the detailed technical report including all measurements, analysis, final conclusions and recommendations and present the same to the concerned before our team leaves the site. This will help the concerned to understand the findings in detail and to plan for corrective action appropriately.
