Modelling of Multiphase Flow in Ironmaking Blast Furnace X. F. Dong, A. B. Yu,* , and J. M. Burgess Laboratory for Simulation and Modelling of Particulate Systems, School of Materials Science and Engineering, The UniVersity of New South Wales, Sydney, NSW 2052, Australia D. Pinson, S. Chew, and P. Zulli Bluescope Steel Research, P.O. Box 202, Port Kembla, NSW 2505, Australia A mathematical model for the four-phase (gas, powder, liquid, and solids) flow in a two-dimensional ironmaking blast furnace is presented by extending the existing two-fluid flow models. The model describes the motion of gas, solid, and powder phases, based on the continuum approach, and implements the so-called force balance model for the flow of liquids, such as metal and slag in a blast furnace. The model results demonstrate a solid stagnant zone and dense powder hold-up region, as well as a dense liquid flow region that exists in the lower part of a blast furnace, which are consistent with the experimental observations reported in the literature. The simulation is extended to investigate the effects of packing properties and operational conditions on the flow and the volume fraction distribution of each phase in a blast furnace. It is found that solid movement has a significant effect on powder holdup distribution. Small solid particles and low porosity distribution are predicted to affect the fluid flow considerably, and this can cause deterioration in bed permeability. The dynamic powder holdup in a furnace increases significantly with the increase of powder diameter. The findings should be useful to better understand and control blast furnace operations. 1. Introduction An ironmaking blast furnace (BF) is a complex reactor that involves counter-current, co-current, and/or cross-current flows of the gas, powder, liquid, and solids phases. As shown in Figure 1, in this process, iron-bearing materials and coke are charged at the top of the BF and hot air (blast) enters the furnace through the tuyeres in the lower part and combusts carbonaceous materials (coal, coke), to produce a reducing gas. As the reducing gas ascends, it reduces and melts the iron-bearing materials to form liquid iron and slag in the cohesive zone (CZ). These liquids percolate through the lower zone coke bed to the hearth. If pulverized coal injection (PCI) is practiced and at high rates, unburnt coal may leave the raceway region entrained in the gas. 1 Under some conditions, the holdup of the fines results in deterioration of furnace permeability. Understanding the behavior of this multiphase flow system is very important for process control. Because of the difficulty of in situ sampling and measurement in the BF, numerical modeling and simulation, often coupled with physical modeling, has had an important role in achieving this goal. 2,3 Various models have been developed previously to numeri- cally investigate gas-solid, gas-liquid, and gas-powder flows in packed beds, as briefly described in the following. Typically, two approaches have been used to model solid flow: discrete and continuum. 4–11 The discrete approach is based on the an- alysis of the motion of individual particles and has the advantage that there is no need for global assumptions on the solids, such as steady-state behavior or uniform constituency, and/or con- stitutive relations. However, this approach is still not suitable for simulation of large-scale reactors such as a BF that contains a very large number of particles, because of the current limited computational capacity. Instead, the continuum approach, which treats the solid particles as a continuous phase, is widely applied to predict the flow of solids, including velocity distribution and flow zones. In particular, one solution procedure has also been proposed to calculate the profile of the stagnant zone. 10 Knowledge of the burden distribution and velocity field makes it possible to compute the flow fields of other phases. Liquid flow in the BF has several interesting features that distinguish it from other gas-liquid co-current and counter- current flows in the chemical and manufacturing industries. These include the nonwetting between liquids and coke particles, * To whom correspondence should be addressed. Tel.: 61 2 93854429. Fax: 61 2 93855956. E-mail address: a.yu@unsw.edu.au. Figure 1. Schematic illustration of internal flow phenomena in a blast furnace (BF). Ind. Eng. Chem. Res. 2009, 48, 214–226 214 10.1021/ie800147v CCC: $40.75  2009 American Chemical Society Published on Web 06/27/2008