A Study Of Heat Transfer In Special-Shaped Pipes Applied To Blast Furnace Hearth

With the progress of blast furnace ironmaking technology,it has been paid much attention to improve the service efficiency of blast furnace,extend the service life of blast furnace and reduce the cost of ironmaking,and become an important research content.Judging from the existing service life of the blast furnace in our country,the application of the cooling device can significantly improve the service life of the blast furnace.According to past experience,engineering calculation is usually used to calculate the convective heat transfer coefficient between water and water pipe in the heat transfer calculation of cooling wall.The empirical formula of convection heat transfer coefficient is a one-time one-dimensional equation,which is suitable for the range of low-speed turbulent flow in the pipe cooling water.In order to ensure the packing layer reaches the curing temperature during the blast furnace,the cooling water in the water pipe is usually in an ultra-low water speed working condition,and the empirical formula is not applicable.In this paper,the most widely used smooth cast iron cooling wall is taken as the research object to conduct the heat transfer analysis focusing on the convective heat transfer in the pipe.The expression of convection heat transfer coefficient in the opposite-end water pipe is deduced by using the numerical equation.Wall cooling effect,to provide a reference for the cooling wall optimization.The research contents are as follows:(1)The cooling of the cooling wall is realized by the convection heat transfer between the water and the water pipe.Different sections of the water pipe have different convection heat transfer coefficient expressions.Considering that the empirical formula of convective heat transfer coefficient is limited in scope,it is not suitable for ultra-low or super-high water velocity.Based on the four types of shaped pipes,such as round pipe,oval pipe,hexagonal pipe and rectangular pipe,The corresponding convective heat transfer coefficients of water pipes under different water flow conditions were calculated.(2)The heat transfer analysis of blast furnace hearth using round tube,oval tube,hexagonal tube and rectangular tube stave was carried out by ANSYS respectively.By comparing the temperature and heat flux,the convection heat transfer coefficient Conducted a comparative analysis to determine the applicable range of water velocity,expanding the use of the project convection heat transfer equation range.(3)The simulation of the cooling state of the circular pipe,the oval pipe,the hexagonal and the rectangular water pipe cooling wall,adding the analysis of the air gap outside the pipe in the process of analysis and improving the analysis efficiency by simplifying the air gap Accuracy,and the fluid simulation results with the two-dimensional heat transfer model of the hearth cylinder were compared,the deviation within 15%,and the bias was analyzed.Obtained by different sections of the water pipe conditions with the water flow rate will enhance the cooling effect,but after the water reaches a certain extent,the impact of reduced.The results show that the required water flow rate from low profile pipe to low profile pipe at the same cooling temperature are:hexagonal pipe,rectangular pipe,oval pipe and round pipe respectively,which provides a reference for the optimal design of cooling stave.