The Overall Design And Numerical Analysis Of The Vertical Countercurrent Heat Exchanger

In the iron and steel industry,the energy consumption of sintering process accounts for 10%to 15%of the total energy consumption,which is the second largest energy consumption process after the iron-making process.Sintering waste heat resources mainly include sinter sensible heat and waste gas sensible heat,accounting for 40%and 30%of the total heat of sintering process respectively.However,most of the existing waste heat recovery systems are based on ring coolers,which have the disadvantages of serious air leakage and low waste heat recovery efficiency.Therefore,inspired by the dry coke quenching technology,our research group developed a vertical waste heat recovery system that maximizes the sensible heat of sinter by gas-solid countercurrent heat transfer while cooling the sinter.First of all,on the basis of referring to the structure of drying-out furnace and ironmaking blast furnace,this paper develops the function and process flow of sinter vertical waste heat recovery system,and preliminarily designs the core vertical countercurrent heat exchanger,and determines the structure form of the charging device,heat exchanger body,air distribution device and discharging device.Meanwhile,based on the relationship between sinter water equivalent and cooling gas water equivalent,the structural parameters and operating parameters of vertical countercurrent heat exchanger are designed and calculated by using the mathematical equations of convection and heat conduction in heat transfer.Then the steady state heat transfer model of local non-thermodynamic equilibrium is established to calculate the gas-solid heat transfer process in vertical countercurrent heat exchanger.In the process of gas-solid heat transfer in the heat transfer unit using FLUENT software,the local non-thermodynamic equilibrium double energy equation suitable for steady gas-solid heat transfer was derived based on the analysis of porous media theory and heat transfer theory,and the gas flow state and flow model of the sintered ore deposit were determined.At the same time,the cooling section of the heat exchanger was taken as the calculation area,and the grid was divided by combining structured and unstructured methods.The material properties and boundary conditions of the heat exchanger were set by referring to the physical parameters of sinter and cooling gas in the actual production.Finally,based on the above calculation model,a vertical countercurrent heat exchanger equipped with a 360m~2sintering machine in China was used as the research object to carry out numerical calculation of the gas-solid heat transfer process in the sintered ore deposit layer in the heat transfer device,by which the basic laws,main influencing factors and influencing laws of the gas-solid heat transfer process were analyzed.The structural parameters and operating parameters of the heat exchanger were optimized and analyzed by using the orthogonal experimental design method,and the recovered cooling gas exergy was determined as the orthogonal experimental index,and the influence law of its structural parameters and operating parameters on exergy was analyzed,by which the optimal structural parameters and operating parameters of the heat exchanger were obtained.