Title : Numerical study of iron ore reduction in MIDREX Shaft
Traditional ironmaking is responsible for the emissions of greenhouse gases, leading to major environmental problems caused by the enormous amount of CO2. Reducing CO2 emissions and energy consumption is one of the most important issues in recent decades. It has been proven that hydrogen may be accountable as a reductive agent and an environment-friendly material that can sustain production processes using alternative fuels. MIDREX furnace is one such alternative ironmaking process, in which direct reduced iron (DRI) is produced in a counter-current gas-solid moving bed reactor, using natural gas as fuel. MIDREX furnace is a counter-current gas-solid reactor bed that converts solid iron ore pellets into sponge iron using natural gas reforming gas. The present study demonstrated a MIDREX process based on the governing differential equations representing material and heat balance in the solid and gaseous phases. In this work, ordinary differential equations in an iterative method have been solved using MATLAB program to estimate the concentrations and temperature profile of all the species and the reduction behavior of the pellets along the length of the furnace. In the present work, a mathematical model has been developed to study the reduction zone of the MIDREX furnace, which effectively predicts the variation in the reaction extent and reacting gas composition along the length of the reactive zone. Our model predictions are in good agreement with plant data. The validated model can be used to estimate the variations of CO2 content in the top gases for the given production rate concerning the inlet gas temperature and compositions with the desired level of metallization.