Drying drums are widely used for drying materials in many industries. At the same time, the temperature of the drying gases can exceed 1000 °C, and the materials being dried or the evaporated media can be highly aggressive, which can lead to the destruction of the material of the drying drums. As a result of comprehensive studies, it has been established that the probable causes of cracking of drying drum linings under operating conditions of the drying-granulation department of a potassium ore processing plant are thermal stresses. The research results are confirmed by the results of the analysis of the composition and mechanical properties of the drum material, as well as the calculations performed and modeling results. It has been established that thermal stresses are caused by the difference in linear thermal expansion of the lining and the drum due to significantly different temperature coefficients of linear expansion. The drum and inner lining expand by 18.5 mm and 26 mm, respectively, and the calculated difference is approximately 8 mm. Contact force between the lining and the body of the drying drum reaches 54.44 MN. Maximum stresses experienced by the body of the drying drum do not exceed 6 MPa. The microhardness of austenite grains through which the crack directly passes was ≈150 kg/mm2, and that of unbroken grains was ≈180 kg/mm2. Additionally, cracking of the linings due to thermal stresses is associated with the design features of the drum dryer, expressed in the rigid structure of the lining and drum along the transverse axis. The further development of cracks occurs due to, cyclic thermal effects, and the chlorides enter the cracks.
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