Establishing Heat Transfer Model And Numerical Analysis In The Interior Of The Rotary Kiln

Rotary kiln is widely used in many fields,such as building materials,metallurgy,chemical industry and so on.It is a large heat transfer equipment with many functions,such as fuel combustion,material transfer and calcination,waste degradation and so on.The rotary kiln can be used for the treatment of solid materials by mechanical,physical or chemical treatment.It has the advantages of large volume,high mixing rate,strong adaptability,etc..In order to improve the thermal efficiency and energy efficiency of the rotary kiln,it is of great significance to analyze the heat transfer model and to investigate the experimental study on temperature distribution outside kiln.In this paper,the temperature distribution characteristics of rotary kiln are studied by the method of combining one-dimensional and three-dimensional numerical analysis and experimental investigation.The main work is as follows:1.Design experiment scheme,explore the wall temperature distribution and the coating's distribution of the inner wall of the kiln.Based on the results of material composition of heat balance test,the heat absorption and heat release rate of materials in different reaction processes were obtained by quantitative calculation.2.Considering the characteristics of flue gas flow and material movement,a reasonable calculation equation of heat transfer coefficient was selected.The heat transfer process in the kiln was analyzed by taking the influence of the kiln coating on the heat transfer process and the heat absorbed and released by different reaction processes into account.Based on the reasonable assumption,a one-dimensional axial heat transfer model of cement rotary kiln was established.Predict the axial temperature distribution of the flue gas,the material and the inner wall of the kiln,and obtain the numerical analysis results of the rotary kiln temperature distribution and the axial distribution of kiln coating thickness.3.Convert the calculation results of the kiln thickness and the kiln thermal conductivity into the wall thermal resistance and convert the material reaction heat into additional heat flux.Setting corresponding wall boundary condition,constructed a three-dimensional CFD model of rotary kiln with a scale of 1:1.According to the model reasonable simplifying assumptions,setting reasonable turbulence model,radiation model,combustion model and solver settings,the axial temperature distribution of the 3D model of the rotary kiln was obtained,which also be compared with the results of the one-dimensional model.The wall boundary condition was reset up,and the influence of the reaction heat of kiln and the material on the temperature distribution of the rotary kiln was studied under the condition of considering the kiln and the reaction heat.