Alignment measurement taken during normal rotary kiln operation (hot kiln alignment) became industry standard these days. There are many different type of services and different methods of alignment/measurement available. Some of them use the movement of the machinery as an advantage other treat kiln’s operation as an obstacle.
From maintenance point of view alignment starts with the kiln erection. None of the manufacturers (vendors) does not provide any support with regard to the correct geometry and alignment of the kiln after installation. The Customer must take care of it by yourself. Have to monitor kiln condition all the time. All deviation, misalignment caused by installation work or operating conditions can shorten the life time of many components.
Generally the Customer (Cement Plant) has a very short warranties time after kiln erection. A good solution in that case is to have an agreement with third party company for hot kiln alignment services after first few years of kiln operation. In that way it is possible to avoid excessive and premature wear. Also the geometrical and operation analysis can start at a very early stage.
During erection the alignment is very often monitored internally. When the kiln in normal operation (hot condition) we cannot use this method, so all actions should be taken from outside. Relative measurements methods has to be used.
This hot kiln alignment methods has many advantages and benefits. The overall running kiln condition last longer than when it is stopped. It is important to have the perfect geometry the longest possible period of time. Alignment service and measurements can be considered as preventative maintenance strategy.
As mentioned before there are many different methods of hot kiln alignment. In particular:
Method 1 – with the procedure uses optical devices like plummet, steel tape, staff.
Method 2 – procedure uses a computer equipped two laser theodolites communicating each other with the same computer to define and measure base points of kiln geometry in 3-dimensional environment. The geometrical triangulation with the help of computer were used. However this method adaptation to kiln under operation is difficult.
Method 3 – uses projection of moving tires, which often leads to erroneous results.
Method 4 – based on the kiln shell deflection, where the position in not measured at all. In this method rollers are placed according to kiln shell deflection. Other aspects like bearing load, hertz pressures are ignored.
Method 5 – delivery of all key parameters: actual position of kiln shell, external and independent reference coordinate system, electronic/computer records. All the base points are measured in 3-dimensional space directly (both horizontal and vertical plane). The measurement process is fast and the obtained data are accurate.
All of the methods mentioned above has its advantages and disadvantages. Some of them is more accurate but due to limited space difficult to conduct, then using another method is necessary. It is up to the users to choose a procedure which is suitable for a specific situation.