Research On The Heat Transfer Process In A Rotary Kiln For Plasma Disposal Of Aluminum Dross.

Aluminum dross an industrial waste generated during the aluminum smelting process,containing high concentrations of harmful substances such as fluorides and aluminum nitride,which pose a certain threat to the environment and health.Therefore,the disposal of aluminum dross has always been a matter of great concern.A series of policies and regulations on aluminum ash disposal has been introduced by our country to regulate the behavior of aluminum dross disposal.However,there are limitations on existing aluminum dross disposal technologies including pyrometallurgical and hydrometallurgical recycling so that scale application is difficult.Aiming at the shortcomings of the conventional pyrometallurgical technology that requires a large amount of fossil fuels for calcination,Using plasma torch as a heat source to dispose of aluminum dross is proposed in this thesis.The rotary kiln is the main equipment in the calcinating process of the aluminum dross,and the yield and quality of aluminum ash disposal is directly affected by the temperature distribution inside the rotary kiln.It is difficult to comprehensively detect the temperature field distribution inside the kiln using existing detection methods.Therefore,it is necessary to study the heat transfer process in the rotary kiln.We focuses on the experimental rotary kiln and PT-100 A plasma torch of a factory in Zhejiang province.In this thesis.The composition of alumina ash and the chemical reaction mechanism of the main components during the calcination process were analyzed based on the actual operating conditions,and the required temperature for calcination of alumina ash was determined to be 1000℃.The heat transfer process of the rotary kiln was discussed,and a heat transfer model for the rotary kiln and a fluid model for the plasma jet were established.The fluid model of the plasma jet was calculated using COMSOL,and the temperature distribution of the plasma jet in air was obtained.An experiment was designed to verify the reliability of the plasma jet simulation method.Subsequently,the rotary kiln model was simulated and the temperature distribution curve of the kiln outer wall obtained from the simulation was found to be basically the same as the actual measured temperature curve,demonstrating the reliability of the heat transfer model.Utilize a validated mathematical model of the rotary kiln to conduct numerical simulation and emulation of the rotary kiln for large-scale production.The rotary kiln structure is optimized by comparing the simulation results of different kiln structures and materials to extend the length of the effective calcination temperature zone inside the kiln,thereby increasing the yield and efficiency of aluminum dross disposal.This thesis objectively reflects the characteristics of heat transfer in the plasma rotary kiln process and some suggestions for the structural reform of the rotary kiln are proposed to provide theoretical guidance for the large-scale production of aluminum ash disposal.