Numerical and Physical Modeling of Raceway Zone in Melter Gasifier of COREX Process
|Course||Iron and steel metallurgy|
|Keywords||COREX process Raceway zone Physical modeling Numerical simulation|
COREX is the first non-coke iron-making process that has been put in to industrialization. Compared with the traditional iron-making process via blast furnace, COREX process has advantages of using non-coking coal and less pollutant emission.The raceway zone plays an important role in the smelting process of COREX melter gasifier. The shape and size of the raceway, and a series of physical and chemical processes including coke combustion in the raceway play a dominate role in determining the gas distribution and energy supply for iron oxide reduction. It is also the basis of smooth operation of the melter gasifier. Therefore, the research work on the raceway zone of COREX melter gasifer is of great theoretical and practical significance.The physical and chemical processes in the raceway zone of COREX melter gasifier express are similar with those inside the blast furnace. Up to now, very little previous work about raceway zone of COREX melter gasifier has been done in contrast with blast furnace. Based on the research achievements of blast furnace, a cold physical modeling experiment has been done to simulate the behavior of gas and solid phases, and the effects of blast volume and burden discharging (coke combustion) rate on the raceway shape and size have been investigated. An unsteady state numerical simulation on two phase flow in the raceway has been done to analyze the influence of gas blowing velocity on the raceway shape and size. Two dimensional numerical simulation of the particle motion and combustion behavior in the raceway has been done to analyze the gas flow field, pressure field, temperature field, distribution of gas composition, as well as the effect of coke mass flow rate and blowing gas temperature on the maximum temperature in the raceway zone. The conclusions based on the above research works are as follows.(1) Under the operational conditions, both the depth and height of raceway have a linear relationship with the blast volume and burden discharge (coke combustion) rate. The raceway shape is elliptical and hardly affected by the blast volume and burden discharge rate.(2) The raceway depth, height and cavity volume increase with the increment of blast velocity, but not the raceway shape.(3) The gas flow has a rotary motion in the raceway cavity, and there is a circular zone where the gas velocity is relative motionless in the cavity center.(4) The pressure on raceway boundary that faces the tuyere reaches the maximum, decreases along the gas flow motion direction, and research the minimum in the raceway center.(5) The raceway temperature increases as oxygen flow gets deeper in the raceway cavity, and reaches the maximum at the top zone of the raceway zone. The oxygen concentration decreases and the carbon monoxide concentration increases along the combustion process.(6) The maximum temperature of raceway zone increases with the increment of coke mass flow rate that comes from the raceway boundary into the cavity.(7) The maximum temperature of raceway zone increases as the temperature of blowing gas increases.