Overhaul-Period Renewal of Cement Kiln Rotary Drive

The article describes a sudden problem of unplanned failures of the kiln drive due to the destruction of the barb bolts of pillow block bolts. However, the evaluation of the bolts’ state according to the conditions of long-term strength did not confirm the loss of their operability. The model of gradual bolt failures has been developed using the kinetic approach to the destruction of structural materials and the thermodynamic condition for the solids strength in order to theoretically substantiate and solve the problem. The cause of the destruction in a barb bolts material was established after approximately 4-year operation on the basis of the theoretical analysis. Calculations showed that at the end of this lifetime the energy density of the material structure defects reaches a critical value corresponding to its melting enthalpy and leads to its destruction. The undertaken analysis made it possible to propose and justify two new design versions of the kiln rotary drive with almost complete unloading of the pillow block bolts. One of them is connected with the transfer of the drive to the opposite side; the other implies a direction change in the kiln rotation. The second version of the drive reconstruction turned out to be technically and economically feasible as well as the least prolonged. It is commissioned into commercial operation.