Numerical simulation of flash reduction in a drop tube reactor with variable temperatures

摘要

A computational fluid dynamics(CFD)model was developed to accurately predict the flash reduction process,which is considered an efficient alternative ironmaking process.Laboratory-scale experiments were conducted in drop tube reactors to verify the accuracy of the CFD model.The reduction degree of ore particles was selected as a critical indicator of model prediction,and the simulated and experimental results were in good agreement.The influencing factors,including the particle size(20–110μm),peak temperature(1250–1550°C),and reductive atmosphere(H_(2)/CO),were also investigated.The height variation lines indicated that small particles(50μm)had a longer residence time(3.6 s)than large particles.CO provided a longer residence time(~1.29 s)than H_(2)(~1.09 s).However,both the experimental and analytical results showed that the reduction degree of particles in CO was significantly lower than that in H2 atmosphere.The optimum experimental particle size and peak temperature for the preparation of high-quality reduced iron were found to be 50μm and 1350°C in H2 atmosphere,and40μm and 1550°C in CO atmosphere,respectively.