| Abstract Scope |
One of the requirements for sustainable steel production is the production of low-carbon iron, for use with scrap in electric furnace steelmaking. Direct reduction using natural gas in a packed-bed shaft reactor is well-established; the reduction gas in such processes is mainly hydrogen, with a molar ratio of hydrogen to carbon monoxide in range 1.5-3.5. However, the transition to pure hydrogen will change multiple aspects of direct reduction, increasing the endothermicity of the reaction, lowering gas viscosity, increasing reduction kinetics, and increasing the flow rate of gas relative to solids. In this context, it is useful to revisit the choice of pellet size, which reflects a compromise between reduction rate and pressure drop. A one-dimensional shaft model was used to test these effects. Its results indicate that a range of pellet sizes could be used successfully. |