Heat Transfer And Mechanical Properties Of Lower Structure Of Blast Furnace Belly

China's steel mills are all over the country.In the past 20 years,the output of steel ranked first in the world.Blast furnace is one of the main equipments for ironmaking and its longevity technology is very important.Blast furnaces are mainly divided into several parts from top to bottom:the furnace top,the furnace throat,the furnace body,the belly,the bosh,the hearth and the bottom of the furnace.The lower structure of the blast furnace belly includes the area from the bosh to the bottom of the furnace.At present,there are many problems in blast furnaces at home and abroad,such as the impact of heat load on the bosh,the damage of cooling stave due to excessive thermal stress,and so on,which affect the service life of blast furnaces.In the process of blast furnace operation,the hearth and bottom area are directly in contact with liquid hot metal at high temperature,and the phenomenon of burning through occurs from time to time.In short,the bosh,hearth and bottom are the weak links affecting the longevity of blast furnace.Therefore,it is imperative to study the heat transfer and mechanical properties of lower structure of blast furnace belly.Taking the blast furnace of a steel mill as the research object,the heat transfer characteristics and mechanical properties of the bosh and the hearth and bottom structure of the blast furnace are studied.The main research contents include:(1)The finite element model of the thermal structure in blast furnace bosh is established.Under the existing working conditions,the numerical simulation is carried out to analyze the distribution of temperature field and thermal stress field of the thermal structure in the blast furnace bosh under the condition of no slag cover.(2)The cooling effect of blast furnace cooling equipment is mainly realized by heat transfer between water and inner wall of water pipe.In the working process of blast furnace,the flow of cooling water takes away the heat,reduces the temperature of the cooling stave and protects the blast furnace shell.The convection heat transfer coefficient is related to the shape and size of the heat transfer surface,the flow state of the fluid and the physical properties of the fluid.Through the equation of the criterion number,the convection heat transfer coefficients of copper cooling walls with different shapes of water pipes used recently(double circular pipe,triple circular pipe,elliptical pipe,regular hexagon pipe and rectangular pipe)under different flow rates of cooling water were calculated.The heat transfer characteristics of cooling pipes of different shapes are compared under the same circumference and cross-sectional area.The influence of different proportion of short axis and long axis on the maximum thermal stress of rectangular and elliptical tube cooling staves are analyzed,and the optimum type of cooling tube is selected.(3)The elliptical tube stave that ratio of the short axis to the long axis is 0.6 is studied.The single factor(hot gas temperature,brick thickness),multi-factor interaction(cooling stave body thickness and long axis radius,temperature of cooling water and speed of cooling water)are analyzed of the effect on the heat transfer and mechanical properties of the stave.(4)The quality of blast furnace drying is discussed.The influence of cooling conditions on the quality of blast furnace is analyzed based on the highest temperature of ramming filler in hearth and bottom of blast furnace.The feasibility of stopping water drying is discussed,and the drying conditions of blast furnace are improved to provide reference for the practice of high quality drying.