Heat Transfer Calculation Of Rotary Hearth Furnace Molten Pool Tapping Model And The Thermal Design

The rotary hearth furnace molten pool is an important production equipment of steel smelting, and the cost of construction and maintenance is huge. Thus the extension of rotary hearth furnace molten pool life can greatly reduce the cost and achieve more economic benefits. During rotary hearth furnace molten pool process, it usually should replace refractory materials and repair rotary hearth furnace molten pool lining to protect the security and integrity of its local parts. But it is difficult for the bottom and side wall of molten pool. The molten pool bottom contacts with the high temperature iron directly in the process of tapping iron, and the erosion is serious. Furthermore, the local wreck of hearth can result in the repair of the rotary hearth furnace molten pool. So the life of rotary hearth furnace molten pool mainly depends on the hearth.This paper gives an analysis of the rotary hearth furnace molten pool hearth's thermal design. Through the studies of heat transfer balance curve, it takes the 1150? isothermal which is iron's solidification line as the estimate of erosion boundary and study the thermal resistance of the lining, the outer cooling condition and the critical thickness of molten pool under heat convection.Accoding the thermal design, it controls the 1150? isothermal in a certain position through the reasonable cooling to prolong the life-span and make sure the safety of the molten pool.The overall structure of the furnace hearth is quite complex. The lateral of the furnace lining contains packing, cooling wall and cooling pipes so on. During the process of modeling, according to the principle of heat transfer, this paper equivalently converts the convective heat transfer coefficient of the sidewall and bottom of the hearth to greatly simplify the structure of cooling walls to make the modeling and calculation easier.This paper established the calculation model of furnace hearth with the method of porous medium, used the method of lined unit and molten iron unit substituting mutually to simulate erosion boundary moving automatically, took the molten iron solidification line as the erosion criterion we get the erosion shape of the ideal tapping iron condition which is the operation model. In addition, we get the temperature field and the iron flow field of the operation model, and has discussed the influence of line thermal conductivity, convective heat transfer coefficient of furnace's sidewall and bottom, capacity utilization coefficient to the heat transfer balanced boundary of the operation model. This is important to the research of 1150? isothermal.This paper analysed the minimum thermal stability safety thickness of the cooling wall and the critical thickness which molten iron begin to solidfy, then discuessed a new criterion which based on the critical thickness is greater than the safety thickness. These have certain reference value to the design and operation of rotary hearth furnace molten pool.