Rotary kiln shell tends to heat damage. The “hot spot” formation can appear every time when refractory fall at some part of shell segment. Sometimes it looks like red spot on shell surface. The size is from couple of centimeters up to much larger area. Also some other symptoms like blisters on the surface is a very important warning that should never be ignored. To monitor thermal distribution of kiln shell the Cement Plants crew generally use infrared thermal scanners. These equipment linked with advanced software allows to show both actual, real-time temperature and history data in order to perform analysis. Thermal scanner is a very important preventive maintenance tools that allows to detect potential cause of problems with klin shell deformation. With proper data analysis adequate steps can be taken long before kiln shell damage.
The overheated part of shell is just the beginning of problems. After overheating the “hot spot” shrink and flatten. It may cause the bending of the shell or even shorten it. The most common extreme cases is “crank shaft” and “dog leg” formations.
The overheated parts creates deviations in kiln shell. These, in turn causes other problems. At the area where the hot spot took place it is difficult to get good quality of refractory lining. Next potential problems is bending stress increase. The tube rotates unstable moving higher stress from one support roller to another and from pier to pier. Rotary kiln and its supports (rollers, shafts, bearing) are designed to operate with straight kiln shell tube. Each deviation (parameters out of design tolerance) creates the chain of causes which has significant influence to whole kiln operation. Because kiln is a rotary equipment each rotation creates small damage which finally leads to extreme failure. Possible symptoms are: hot bearings, tire and shell cracks, shaft damage, support failure etc.
Next consequences of shell bending of its original axis is excessive tires axial and radial run-out parameter. The value and the type depends on the kind of the shell crank, but anyway it creates more damage especially on running surfaces. Also the meshing of gear and pinion starting not to work properly. The kiln inlet and outlet sealing can affected as well.