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Introduction

Solid burden flow behaviour is of major interest in classical blast furnaces, FINEX®/COREX® plants and similar aggregates. The objective of this project is to model and simulate key elements of iron making technologies such as the raceway and the reactive moving bed within blast furnaces and COREX/FINEX-melter gasifier units or iron ore reduction within a fluidised bed reactor of the FINEX-process. Within former activities in the K1MET consortium, first models have been developed. In the next phase, these models shall be improved for better predictive capabilities and numerical efficiency, also aiming at integrating the models into the K1-MET Simulation Platform (Project 4.1).

  • CFD modelling of smelting and direct reduction furnaces
  • Coupling of CFD simulation to DEM simulation of Project 4.3
  • Optimization of raw material usage, productivity and design of smelting reduction facilities

Methodology

Within project P (4.2 Bulk Solid Models) simulation tools for reactive moving and fluidized beds shall be improved further in terms of predictive capabilities and computational efficiency. Since the total number of particles involved in most industrial moving and fluidized beds is extremely large, it may be impractical to solve the equations of motion for each particle. It is, therefore, common to investigate particulate flows in large process units using averaged equations of motion. These two-fluid model (TFM) equations take account of the behaviour of the particles by considering a huge ensemble of particles and, thus, closures are required for the solids stresses arising from particle-particle contacts. Recently, numerical simulations, which are based on the TFM equations, have become a successful design tool for modelling pilot plant scale moving and fluidized bed reactors. In the first phase of the K1-MET it has been shown that these simulations are able to accurately describe the hydrodynamics of inert lab-scale fluidized and moving-bed reactors. Due to computational limitations the investigation of industrial scale reactors including heat transfer and chemical reactions is, however, still unfeasible. It is, therefore, common to use coarse grids to reduce the demand on computational resources. However, such a procedure inevitably neglects small (unresolved) scales, which leads to a considerable overestimation of gas-solid drag force, the gas-solid heat transfer and the chemical reaction rates. It is generally agreed that the influence of these small scales on the drag force is a key parameter in the prediction of the correct hydrodynamics and chemistry of moving and fluidised beds.

Results and application

Project P4.2 Bulk Solid Models shall result in realistic predictions of metallurgical aggregates (e.g. blast furnace, COREX®, MIDREX®, FINEX®) at plant scale. This will enable industrial partners to optimize their operation (e.g. by maximizing the conversion rate in pulverized coal injection or by applying dedicated solid charging recipes). Furthermore, plant manufacturers will have a reliable tool for up-scaling and re-design of existing plants. A CFD-model on an open-source platform will allow for the computation of coke and alternative reducing agent conversion in the raceway cavity of blast furnaces. It will be applied to investigate various blast furnace operating conditions in order to study the conversion grade of injected materials (e.g. coal, plastics etc.). The model shall also allow for coupling the CFD simulation to DEM approaches (P4.3) to include the impact of changing hot blast / injection parameters on the raceway formation kinetics. The modelling method is also applied to simulation of smelting and direct reduction furnaces (reduction shafts, melter-gasifiers and blast furnaces) as well as of the FINEX process. The models are used to optimize raw material usage, productivity, and design of smelting reduction facilities. The modelling methods of this project are implemented in the open source CFD code OpenFOAM and are integrated in the K1-MET Simulation Platform of Project 4.1.