As described in one or more previous Metso blog articles, horizontal and vertical misalignment issues on rotary kilns can lead to unpredictable operation and decreased reliability.
The contributing factors that are most likely to cause alignment issues include:
- Component wear
- Component replacement
- Adjustment of carrying rollers
- Foundation settlement
For kilns with three (3) or more piers, proper alignment evenly distributes loads across all piers.
The most widely accepted method for alignment is performed under normal operating conditions and is aptly referred to as a hot-kiln alignment. Depending on condition, we recommend hot-kiln alignment service including any required kiln realignment and leveling along both horizontal and vertical planes every one (1) to three (3) years. We also recommend checking alignment and kiln slope again before and after any major component replacement.
Because OEMs and repair companies apply different methods to calculate kiln misalignment, you might find it challenging to evaluate the service proposals you receive from suppliers performing their version of a hot-kiln alignment.
Asking thorough questions about the service can help you identify what is included and what types of instrumentation will be used. In turn, you can then determine what service is right for your kiln.
Some typical questions to ask:
- How will measurements to correct kiln misalignment be taken?
- What degree of accuracy is provided by their equipment?
- What other services are included with the Hot Kiln Alignment?
- Are corrective roller adjustments included and how will these be carried out?
Most services include some form of kiln mechanical survey where other measurements besides kiln misalignment are calculated. These items should include a shell survey (shell runout and shape distortion), tire wobble, gear radial, and axial runout, shaft deflection, ovality, base and roller slopes, and a visual inspection of the rotary kiln. It is also important to measure the carrying roller and tire diameters to document wear profiles and consider their long term serviceability.
One of the most important considerations in selecting a provider is whether or not they include alignment adjustments. Adjustments on kilns are one of the more critical and have the greatest potential to cause production upsets and plant shutdowns if not done correctly. It takes experience to understand, analyze, adjust and monitor to ensure that alignment and thrust are adjusted correctly.
Coupled with the alignment information, the additional measurements give a holistic view of the rotary kiln as a complete functioning unit. As a service provider or equipment owner, you can now make more informed decisions that are supported by real-world data.
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