Computational Modeling of Iron-oxide Pellets Reduction using H2 in a Fixed Bed

Abstract

Full-fledged computational modeling of Direct Reduction (DR) reactors encompasses single pellets models and the step-wise scaling-up to industrial-scale reactors. The specific focus lies here on scale-up from a single iron ore pellet to a fixedbed reactor model. However, this process poses several challenges like, a) Synthetic packed-bed structures need to be generated instead of a realistic image-based method due to the high cost, b) Good quality mesh for multi-pellet fixed bed is difficult to generate and c) Scaling up to a CFD environment is cost-intensive. Furthermore, the correct modeling of transport and kinetics-related processes for a single pellet is a prerequisite for a meaningful scale-up. This has not yet been demonstrated. In this work, the chemistry and transport data for the reduction of single iron oxide pellets with H2 gas, obtained from a previously developed 1D solid porous model will be used. The purposes of this article are 1) Proposing a CFD model that reproduces single pellet reduction experiments with H2 gas for wide experimental conditions in a 3D-CFD environment. 2) Computationally generating a random packing of 212 industrial pellets (0.5 kg) by applying the discrete element method (DEM) to simulate a lab-scale fixedbed reactor. 3) Creating a 3D domain, based on the particle position data from the previous step and meshing the pellets and the voids among them in different refinements. 4) Reproducing a multi-pellet fixed-bed experiment with pure H2 from literature. 5) Investigating the effects of temperature variations in the bed. In this way, the concept of scaling up to multi-pellet fixed bed model simulation with H2 will be demonstrated successfully