IRONARC; a New Method for Energy Efficient Production of Iron Using Plasma Generators

University essay from KTH/Materialvetenskap

Abstract:

The most widely used process to reduce iron ore and to produce pig iron is the blast furnace. The blast furnace is a large source of CO2 emissions since it is a coal based process and due to that the main energy source and reducing agent is coke, it is difficult to reduce these further. IRONARC is a new method used to produce pig iron by reducing iron ore and all the energy used for heating comes from electricity, which gives the opportunity to use renewable resources. The process uses plasma generators that inject gas at high temperature and velocity into a slag that consists of iron oxides. The iron oxides are reduced in two steps that appear by using gas as reduction agent in the first step and carbon in the second step.   It exists in a smaller pilot plant scale and this project was the first step in the future upscaling of the IRONARC process.

Computational Fluid Dynamics (CFD) modelling was used and the goal was to determine the penetration depth of the IRONARC pilot plant process by numerical simulation in the software ANSYS FLUENT. The penetration depth is of importance because to be able to scale up the process it is important to know the flow pattern and the structure of the flow in the process, which is dependent on how far into the slag the gas reaches.

Two numerical models were made. First an air-water model that described the initial penetration of air injected into water. The air-water simulation was made with parameters and data from an experiment found in literature. This was done to build an accurate CFD model for the penetration depth in FLUENT and validate the model with the results of the penetration depth from the experiment. The air-water simulation gave good and promising results and yielded the same result regarding the penetration depth as the experiment.  The model for the penetration depth was then used with the IRONARC geometry and parameters. After simulation the penetration depth of the IRONARC process was determined. For the future, the penetration depth of the pilot plant needs to be measured and compared with the simulated result for the penetration depth. 

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