Application of a Coal Combustion Model in the Design of Blast Parameters for an Ironmaking Blast Furnace

With significant economic drivers to reduce consumption of expensive coking coal, Pulverized Coal Injection (PCI) commenced at BlueScope Steel in 2002, at injection rates ranging between 100 and 150 kg-coal/tonne of liquid iron. The key limitation to injection rates is associated with the reduction in packed bed permeability via additional char load into the furnace. The coal is injected via a simple co-axial lance, consisting of an inner pipe (for coal and carrier gas) and an outer annulus (for cooling gas to protect the lance from the high furnace temperatures). The cooling gas can be compressed air, natural gas or pure oxygen. Depending on the choice of cooling gas, the oxygen-to-carbon ratio of the system will change. In this paper, the application of a validated three-dimensional numerical model of the blowpipe/tuyere/raceway is described. The model is used for various plant-specific investigations of blast parameters such as oxygen enrichment, blast temperature and atomic oxygen-to-carbon ratio. The model results show the sensitivity of coal burnout to different operating parameters and confirm that burnouts higher than 80% are difficult to obtain due to the short residence times of the coal

Simulation of flow and heat transfer in blast furnace hearth

The erosion of hearth refractories is the main limitation for a long campaign blast furnace life. An in-depth understanding of the flow and heat transfer is essential in order to identify the key mechanisms for the hearth erosion. In this study, a comprehensive computational fluid dynamics model is described which predicts the flow and temperature distributions of liquid iron in blast furnace hearth, and the temperature distribution in the refractories. The model addresses conjugate heat transfer, natural convection and turbulent flow through porous media, with its main features including three-dimensional, high grid resolution and a wide range of geometrical and kinematic scales (from taphole diameter to hearth outside diameter). The melt flow was simulated using improved transport equations, including a modified k-ε turbulence model and a thermal dispersion term.The predicted results show a well-organized flow pattern: two large scale recirculation zones are separated vertically at the taphole level. This flow pattern controls the temperature distribution in the liquid phase, so that the temperature remains nearly uniform in the upper zone, but changes mainly across the lower zone. The effects of several important factors are examined, such as the fluid buoyancy vs constant fluid density, and the shape and position of coke free zone (different shapes of coke free zones were assumed in connection with the reported dissection study). The inclusion of fluid buoyancy was found to be most important for the flow pattern observed. Comparison with the plant data from BlueScope Steel's Port Kembla blast furnaces shows that the pad temperature is most sensitive to the thickness of protection layer in the hearth lining

Chris is a Fellow of the Australian Institute of Navigation,

Newcastle upon Tyne, UK. Joel has assisted in the development of the Locata receiver and testing of the Locata technology. Other current research interests include pseudolites, GPS receiver firmware customisation and high precision kinematic GPS positioning. Chris Rizos is a graduate of the School of Surveying, Th