Numerical Simulation Of Fluid Flow In Blast Furnace Hearth

The comprehensive benefits of large-scale blast furnaces are of obvious significance.At present,industrialized countries in the world have basically realized the enlargement of blast furnace,and China is actively promoting this process.Many advantages of large-scale blast furnaces are the result of a series of highly integrated innovations in technology and practice.However,longevity of blast furnaces is the key to embodying the advantages of size enlargment,and short-life blast furnaces have no advantages.Practice has shown that the furnace belly,bosh,its lower part and the hearth area that are subject to large thermal loads are the key parts that determine the life of a modern blast furnace.In recent years,through the use of advanced cooling equipment and refractory materials,the problems of high repair frequency and short life of the furnace belly,bosh and its lower part have been basically solved,but the problem of the hearth is still occuring.In fact,under the new situation of high productivity and low raw material quality,the bottlenecks that limit the longevity of the blast furnace are gradually shifting from furnace belly,bosh and its lower part to the hearth,so it is urgent to rely on technological progress to prolong the life of the hearth and then to lay the foundation for the smooth realization of blast furnace size enlargement.In addition to the storage of slag and hot metal,the blast furnace hearth is also periodically discharged,so it is always subject to extremely complex physical damage and chemical erosion.During the discharge process,the mechanical scouring and abrasion of the furnace lining by the hot metal is the main cause of furnace burn-through.High productivity usually means greater tapping rate,which will inevitably increase the erosion of the furnace lining.Therefore,fluid flow behavior in the hearth of a large blast furnace under high productivity has become one of the focuses in the related field.Therefore,the present study takes a 5500 m3 large blast furnace in a domestic plant as the research object.A three-dimensional computational fluid dynamics model is established by comprehensively considering the momentum transfer,heat transfer in the hearth and the more realistic boundary conditions of the taphole.The influences of the state of the deadman and the length of the taphole on the flow behavior of hot metal and the erosion of hearth refractory are investigated.The following main conclusions are obtained.(1)The state of the deadman in the hearth determines the streamlines of hot metal.During the discharge process,hot metal tends to flow into the coke-free space with small flow resistance,so that the refractory material in the vicinity of the coke-free space is subjected to severe mechanical erosion.The influence of floating height of the deadman on the erosion intensity of hearth lining is non-linear.When the floating height of the deadman is 0.1 m,the erosion of the lining at the side wall of the hearth caused by hot metal flow is the most serious.(2)As the depth of the taphole increases,the velocity of hot metal flow adjacent to the refractory wall at the taphole side gradually decreases,and the intensity of refractory erosion gradually decreases.When the taphole is deepened from 3.8 m to 5 m,the velocity of hot metal flow adjacent to the refractory wall at the taphole is reduced by about 50%.