The power generation industry in the state of Victoria, Australia stands to gain significantly from process improvements and optimization which can potentially lead to cleaner production of cost effective electricity. The efficient operation of lignite based tangentially-fired combustion systems depends on critical issues such as ignition and combustion of the fuel, which are largely controlled by burner aerodynamics. The geometry of the burner and the ratio of velocities between the primary and secondary jets play an important role in achieving stable combustion, high burnout of fuel, low production of pollutants and control of fouling. Slot-burners are a vertically aligned stack of rectangular nozzles delivering primary fuel and secondary air jets, and are commonly used in tangentially-fired boilers. To obtain a better understanding of the overall combustion process, it is important to understand the aerodynamics of jet development from these burners. The starting point of this research was a CFD investigation of aerodynamics in the near-burner region of isolated rectangular slot-burners, using isothermal conditions, for various secondary to primary jet velocity ratios (φ). Cross-flow was then added to replicate a near-burner flow field similar to that found in a tangentially-fired furnace and the effect of changing φ in the near-burner region of the developing jets was again investigated. Experiments were carried out on an isothermal physical-burner model to obtain mean velocity and turbulent statistics for different nozzle geometries and a range of φ. A computational fluid dynamics investigation of these same jets was also performed to gain further insights into the complexities of flow field with experimental results used to validate CFD predictions. The primary jet substantially deviated from the geometric axis of the burner towards the furnace wall and became very unstable for higher φ. The causes of unfavourable aerodynamics were discussed and suggestions were made on possible remedies for such behaviour. Conventional lignite combustion in a full-scale tangentially-fired furnace was modelled. The model was used to assess the possibility of utilizing a new type of mechanically thermally dewatered (MTE) coal in existing furnaces.

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The radiation heat transfer from an argon and a nitrogen transferred-arc column to a cylindrical enclosure was measured. The rate of heat transfer was successfully correlated in a non-dimensional manner, with respect to the arc length within the enclosure and the enclosure diameter for the section of the arc column located within the enclosure, and with respect to the arc length outside the enclosure and the enclosure diameter for the section of the arc column outside the enclosure. / It was discovered that tangential injection of a particulate feed material into the cylindrical enclosure led to the formation of destabilizing lump-like deposits on the roof and wall of the enclosure. Feeding vertically through the roof of the enclosure in the presence of a vortex resulted in the formation of a uniform film deposit and stable operation. Under these conditions, up to 49% of the incident radiant energy emanating from the arc column to the sleeve surface was absorbed by the feed. / The carbothermic reduction of a fine (3-10$ mu$m) V$ sb2$O$ sb5$ powder in the plasma furnace resulted in the production of a commercial ferrovanadium alloy of controllable vanadium content. Particulate losses to the exhaust gases were very low, in the order of 2%. Specific energy consumption was 17kWh/kg of vanadium produced. Based on the results of these tests, specific energy consumption at a larger scale would be reduced by at least 50%.

No description available.

Pulverized coal injection (PCI) technology is widely practised in blast furnace ironmaking due to economic, operational and environmental benefits. High burnout of pulverized coal in the tuyere and raceway is required for high PCI rate operation. A comprehensive review reveals that although there have been a variety of PCI models, there is still an evident need for a more realistic model for PCI operation in blast furnace. Aiming to build a comprehensive PCI model of a full-scale blast furnace, this thesis presents a series of three-dimensional mathematical models, in terms of model development, validation and application, in a sequence from a pilot-scale to a full-scale, from a simple to complicated geometry, from a coal only system to a coupled coal/coke system. Firstly a three-dimensional model of pulverized coal combustion is developed and applied to a pilot-scale PCI test rig. This model is validated against the measurements from two pilot-scale test rigs in terms of gas species composition and coal burnout. The gas-solid flow and coal combustion are simulated and analysed. The results indicate that the model is able to describe the evolutions of coal particles and provide detailed gas species distributions. It is also sensitive to various parameters and hence robust in examining various blast furnace operations. This model is then extended to examine the combustion of coal blends. The coal blend model is also validated against the experimental results for a range of coal blends conditions. The overall performance of a coal blend and the individual behaviours of its component coals are analysed. More importantly, the synergistic effect of coal blending on overall burnout is examined and the underlying mechanisms are explored. It is indicated that such synergistic effect can be optimized by adjusting the blending fraction, so as to compensate for the decreased burnout under high coal rate operation. The model provides an effective tool for the optimum design of coal blends. As a scale-up phase, the coal combustion model is applied to the blowpipe-tuyereraceway region of a full-scale blast furnace, where the raceway is simplified as a tube with a slight expansion. The in-furnace phenomena are simulated and analysed, focusing on the main coal plume. The effect of cooling gas conditions on combustion behaviours is investigated. Among the three types of cooling gas (methane, air, and oxygen), oxygen gives the highest coal burnout. Finally, a three-dimensional integrated mathematical model of pulverized coaVcoke combustion is developed. The model is applied to the blowpipe-tuyere-raceway-coke bed region of a full-scale blast furnace, which features a complicated raceway geometry and coke bed properties. The model is validated against the measurements in terms of coal burnout from a test rig and gas composition from a blast furnace, respectively. The model gives a comprehensive full-scale picture of the flow and thermo-chemical characteristics of PCI process. The typical operational parameters are then examined in terms of coal burnout and gas composition. It is indicated that the final burnout along the tuyere axis is insensitive to some operational parameters. The average burnout over the raceway surface can better represent the amount of unburnt coal particles entering the surrounding coke bed and it is also found to be more sensitive to the changes of most parameters. In addition, the underlying mechanisms of coal combustion are obtained. The coal burnout strongly depends on both oxygen availability and residence time. The existence of recirculation region gives a more realistic coal particle residence time and burnout. Compared with the fore-mentioned two models, this model is considered as a more comprehensive model of PCI operation for understanding the infurnace behaviours and provides more reliable information for the design of operational parameters.

Thesis (Ph. D.)--University of New South Wales, 2002. / Also available online.

Thesis--University of Missouri, School of Mines and Metallurgy, 1903. / Year degree was granted determined from "1874-1999 MSM-UMR Alumni Directory". The entire thesis text is included in file. Typescript. Illustrated by author. Title from title screen of thesis/dissertation PDF file (viewed November 13, 2008)

Thesis (M.S.)--Rochester Institute of Technology, 1983. / Typescript. Includes bibliographical references (leaf 56).

Thesis (Ed.D.)--Teachers College, Columbia University, 1972. / Typescript; issued also on microfilm. Sponsor: Douglas R. McManis. Dissertation Committee: Harvey A. Levenstein. Includes bibliographical references.