This work consists of a numerical study of a thermally stressed rotary kiln shell part in a cement plant. The numerical simulations are performed by using the finite volume method for the discretization and the simple algorithm for resolution. The velocity air injection, its temperature, and the kiln rotational velocity are the main parameters under investigation. The distribution of temperature, velocity, and pressure, as well as the evolution of the Nusselt number are determined. In the second step of this study, fins are inserted on the shell to examine their effect on cooling. The results analysis shows that the insertion of fins to the shell has a significant influence on the decrease in temperature of the shell’s external surface. The study shows that this decrease in temperature depends significantly on the air injection rate, not on its temperature, and a bit less on the rotating velocity of the kiln. To avoid overloading our equipment (weight of the shell), only four fins distributed around the kiln are added to explore their effect.