No description available.

No description available.

The ironmaking blast furnace (BF) is a complex reaction vessel involving counter-, coand/ or cross-current flows of gas, powder, liquid, and solids. However, the interactions of these multiphase flows have not been completely understood. The objective of this thesis is to develop a suitable model to simulate the powder flow and accumulation in packed beds and then extend it to numerically investigate the multiphase flow in the furnace. Gas-powder flow in a slot type packed bed has been experimentally studied in order to understand the flow and accumulation behaviour of powder in systems like an ironmaking blast furnace. A variety of variables including gas flowrate, powder flowrate and packing properties have been taken into consideration. It is found that a clear and stable accumulation region can form in the low gas-powder velocity zone at the bottom of the bed. The accumulation region is stable and shows strong hysteresis. The distribution of softening-melting layers in the blast furnace known as the cohesive zone (CZ) is modelled by inserting solid blocks into the bed. The results indicate that the inverse-V cohesive zone shape leads to low powder accumulation within the CZ and at the corner of the bed. A mathematical model is proposed to describe gas-powder flow in a bed packed with particles. The model is the same as the two fluid model developed on the basis of the space-averaged theorem in terms of the governing equations but extended to consider the interactions between gas, powder and packed particles, as well as the static and dynamic holdups of powder. In particular, a method is proposed to determine the boundary between dynamic and stagnant zones with respect to powder phase, i.e. the profile of the powder accumulation zone. The validity of numerical modelling is examined by comparing the predicted and measured distributions of powder flow and accumulation under various flow conditions. With high PCI rate operations, a large quantity of unburned coal/char fines flow together with the gas into the blast furnace. Under some operating conditions, the holdup of fines results in deterioration of furnace permeability and lower production efficiency. Therefore, the proposed model is applied to simulate the powder (unburnt coal/char) flow and accumulation inside the blast furnace when operating with different cohesive zone (CZ) shapes. The results indicate that powder is likely to accumulate at the lower part of W-shaped CZs and the upper part of V- and inverse V-shaped CZs. In addition, for the same CZ shape, a thick cohesive layer can lead to a large pressure drop while the resistance of narrow cohesive layers to gas-powder flow is found to be relatively small. Gas-powder flow in moving beds of solid particles has been numerically investigated, under conditions related to the ironmaking blast furnace and high rate pulverized coal injection. A new correlation, which is formulated to describe static powder holdup in a moving packed bed, is incorporated into the previous mathematical model and applied to a description of gas-powder flow in a blast furnace. Compared with the results of fixed beds, the results show that the solids descent due to the consumption of ore, coke and unburnt char in various regions, together with the non-uniform structural distribution, significantly affects powder flow and accumulation in a blast furnace. Finally, liquid flow is simulated through force balance approach and numerical results are compared with the different liquid inlet distribution under the iron-making blast furnace conditions with gas flow. The results show that the effect of inlet distribution on liquid flow is significant in the upper part of coke region in BF and possible loading and dry zone can be numerically identified. Then, this part of work is incorporated to the developed gas-powder-solid modelling system to investigate the influence of liquid phase on other phases flow in the blast furnace although heat transfer and chemistry are not considered in the model.

No description available.

Thesis (Ph. D.)--University of Sydney, 1987. / Includes tables. Bibliography: leaves 191-199. Also available in print form.

Thesis (B.S.)--University of Missouri, School of Mines and Metallurgy, 1905. / The entire thesis text is included in file. Typescript. Illustrated by authors. Title from title screen of thesis/dissertation PDF file (viewed December 28, 2009)

Thesis (Ph. D.)--Cornell University. / Reprinted from the Journal of physical chemistry, vol. 15, 1911. Bibliography: p. 303-305.

No description available.

Thesis (MAppSc)--University of South Australia, 2000

Multi-phase flows can be found in a range of processes in vanous industries. Ironrnaking blast furnace is one of the typical examples. With high pulverized coal injection rates, complete combustion within the raceway of blast furnace becomes difficult, giving rise to a large amount of powder flow together with gases into the furnace. Thus, the performance of a modern blast furnace with high PCI strongly depends on the characteristics of a multiphase system which involves gas, powder, and liquid superimposed on the motion of solid particles. For this multiphase flow system, the solid (coke, sinter/pellets, etc) movement and liquids (hot metal and slag) and powders (unbumt coal and coke ash) accumulation in the lower region of the furnace are believed to play an important role. This thesis presents an experimental study focus on quantifying the hydrodynamics of gas-powder and gas-powder-liquid flows through packed beds with special reference to blast furnace. The effects of process variables including fluid flowrate and some material properties on powder hold-up, pressure gradient and phase interaction are examined. An experimental study of the hydrodynamics of gas-powder flow in packed beds has been carried out. Glass powder and spherical/non-spherical particles are used to simulate pulverized coal and coke particle respectively. It is found that solid motion, powder flowrate and particle spericity affect powder hold-up and pressure gradient significantly. New correlations are proposed for static and dynamic powder hold-ups to account for these effects based on experimental results. A hydrodynamic model is proposed for gas-powder flow in packed beds with spherical and non-spherical particles. Incorporation these correlations and porosity function into the existed Fanning and Ergun equations, the pressure gradients in fixed and moving beds can be reasonably estimated. The gas-powder-liquid flow through the moving beds is studied. The effects of fluid variables and some material properties on total powder hold-up and pressure gradients have been examined experimentally within the so-called operational regime. The normal and non-wetting treated glass beads, glass powder and water or mixture of water and glycerin are used to simulate coke, pulverized coal and hot metal/slag in a blast furnace. The results indicates that steady-state gas-powder-liquid flow in moving packed beds can be achieved under certain flow conditions since particle motion gives main contribution while it provides a higher bed porosity, enhances powder and liquid flow and removes the accumulation of the powder. The fluid variables and liquid viscosity significantly affect the total powder hold-up and hence pressure gradient but the wettability does not. Based on the experimental results, new correlations for powder hold-up and pressure gradient are proposed for blast furnace modelling in terms of dimensionless number of flowrates for different phases. Incorporation of these correlations and the existed empirical correlations of phase interactions, a hydrodynamic model is proposed to quantify the interaction force between liquid and powder. The results show that this force plays an important role for stable gas-powder-liquid flow in moving beds though it is ignored by most of the previous researchers.