Rotary Kiln Service and Hot Kiln Alignment
The kiln is at the heart of cement and pelletizing plants and plays a vital role in production. Timely, on-site kiln maintenance, such as hot alignment can extend equipment lifetime and minimize wear and tear. Hot kiln alignment allows adjustment of the kiln to the optimum level without interrupting production for multi-pier, refractory-lined kilns. An alignment analysis of the unit is often combined with a Mechanical Survey in order to identify, diagnose, and correct any issues before they develop into major problems. Our company alignment analysis will contain a range of measurements using different tools to ensure all key parameters are analyzed. The use of accurate and proven procedures, performed by experienced and qualified personnel should be of paramount importance to the operator. Our company will have crews with many hundreds of hours of experience on all makes and types of rotary kilns. Our company will use state-of-the-art high frequency laser equipment to capture data with a high degree of accuracy, calculating the position of the kiln shell rotational axis at each support. Calculations include allowance for flexure, shape distortion, and eccentricity of the shell. Achieving high kiln availability is essential to the competitiveness and profitability of customer entire plant. Cement and pelletizing plants need to identify the root causes of kiln failure and eliminate problems before a breakdown occurs. A comprehensive kiln inspection and hot kiln alignment every two to three years helps our clients avoid unforeseen breakdowns and maintain full kiln availability and productivity. We’ll help identify potential causes of failure before problems occur as part of a preventative maintenance strategy. If cement and pelletizing plants already experienced an issue with their kiln, our service will diagnose the actual cause behind the problem and recommend an efficient solution.
Kiln Axis
One of the most important things in kilns with three supports and more is the alignment of the kiln axis in two vertical and horizontal planes. If the axis of the kiln is not aligned, the load distribution on the rollers will not be proportional and as a result, some bearings will be exposed to more pressure, which will increase the temperature and reduce the life of the bearing. Also, the load applied on the shaft of the rollers will increase, which can have consequences such as cracking and breaking the shaft. Another destructive effect of the kiln axis not being aligned will be the increase of tension in the kiln shell and in the contact area of the ring and roller, which will cause cracks in the kiln shell and abnormal wear of the ring and roller.
The experts of our company will determine the position of the kiln axis in two horizontal and vertical planes using highly accurate measuring tools and will determine the amount of movement required for the rollers in order to correct the kiln axis.
Axial Balance
The axial forces of the kiln must be restrained by the thrust roller and the kiln rollers. The contribution of each of these components (thrust roller and rollers) in bearing axial forces is specified and defined. If for any reason (including improper angle of the rollers) the balance of the axial forces of the kiln is out of the normal state, in this case excessive load will be applied to the roller bearings. Applying too much load will result in destructive effects such as increasing the temperature of the bearings and damage and failure of the internal parts of the bearing, as well as the failure of the thrust roller bearing or even the failure of the thrust roller shaft.
By measuring the angle and inclination of the rollers and checking the amount of pressure applied to the thrust roller, our experts will ensure the balance of the axial forces and if the balance of these forces is not correct, the necessary changes in the angle and inclination of the rollers will be determined so that the balance of axial forces returns to its optimal state.
Crank Analysis
In rotary kilns, we face a dangerous phenomenon called CRANK, which can be mechanical crank or thermal crank. The crank of the kiln will be visible to the eye when its amount has increased greatly and reached a dangerous level, so that it causes the ring to lift off the roller. Crank can have destructive effects such as damage to the roller bearing, damage to the ring and roller, and breaking the roller shaft. The amount of crank of the kiln can be checked and commented using a special equipment that measures the deflection of the roller shaft in a non-contact way. If the amount of crank is higher than the allowed value, after identifying the type of crank (mechanical or thermal), an appropriate solution will be provided.
Ovality and Relative Migration
In kilns where the ring and the kiln body are loose, it is very important to know the amount of kiln shell ovality and the relative migration of the kiln ring. Ovality and relative migration rate are interdependent and must be within the allowed range. High or low relative migration are both harmful and have adverse consequences. Too much ovality can severely reduce the life of refractory bricks and is also one of the causes of cracks (longitudinal cracks) on the kiln shell. On the other hand, very low relative movement can also cause deformation of the kiln shell under the ring. During the operation of hot kiln alignment, the amount of ovality will be calculated by the experts of our company, and a suitable solution (increase or decrease the amount of shim under the bearings) will be suggested to correct it.
Kiln Shell Profile Measurement
It is very important to know the amount of deformation of the kiln shell. If the amount of deformation exceeds a certain limit, it will affect the life of refractory bricks. Also, large deformations in some cases are a sign of a decrease in the thickness of the kiln shell in that area, which can be a warning for cracks in the shell. The measurement of deformation in all parts of the kiln shell is done by a special camera for this purpose, and after transferring the camera data to the relevant software, the shape and the degree of deformation of the kiln shell are extracted in two-dimensional and three-dimensional and in finally, it will be visible as a color animation. By watching the mentioned animation, you will easily be able to see the shape and size of the deformation along the entire length of the kiln.
Comprehensive Visual Inspection
In addition to all the necessary measurements that are carried out by the most up-to-date and accurate measuring equipment, a complete visual inspection according to special instructions of all parts of the kiln, including the quality of the surface of the ring and rollers, the placement position of the ring on the roller, the condition of the inlet and outlet seals of the kiln, the lubrication system, the condition of the supporting blocks, axial guides and contact surface of the ring and the roller, the presence of V Gap and other things are done. The results are included in the final report.