Modelling the injection of upgraded brown coals in an ironmaking blast furnace

Victorian brown coal is a low-cost and abundant resource, featuring in high moisture and low ash yield, and has a potential of replacing high grade metallurgical coals in pulverized coal injection (PCI) in ironmaking blast furnace (BF). In this paper, a three-dimensional mathematical model is used to simulate the flow and thermochemical behaviours related to the PCI operation of upgraded Victorian brown coals under full-scale BF conditions. The model geometry covers lance, blowpipe, tuyere, raceway and coke bed at the lower part of a BF. The typical phenomena of in-furnace aerodynamics and physicochemical behaviours relevant to the injection of Victorian brown coals are simulated, in terms of flow, temperature, gas composition and coal combustion characteristics. It is indicated that the model is able to predict the combustion phenomena of Victorian brown coals under BF conditions. The performance between one typical PCI coal and two upgraded brown coals by briquetting and pyrolysis, respectively, are compared. The results indicate the upgraded Victorian brown coal by pyrolysis under given conditions has demonstrated the similar combustion profile with the PCI coal, confirming the feasibility of replacing PCI coal with an upgraded brown coal. Compared with the other two coals, briquetted brown coal of relatively higher volatile matter (VM) led to the release of more fuel gas, thus consuming more oxygen and achieving higher temperature along the tuyere axial and along the raceway boundary. Faster combustion of briquetted brown coal also led to higher overall burnout around the raceway region. The model provides a cost-effective tool to optimize and control the injection of Victoria brown coals under industry-scale BF conditions. (C) 2016 Elsevier B.V. All rights reserved.