Thesis (M.A.)--Virginia Polytechnic Institute and State University, 1984. / Vita. Abstract. Includes bibliographical references (leaves 146-153). Also available via the Internet.

Carbon-bonded silicon carbide and clay-bonded graphite crucibles are used in non-ferrous induction melting furnaces. Silicon carbide crucibles especially have encountered premature failure when used at high power densities and operating frequencies. This is thought to be related to their non-uniform properties. To gain a more thorough understanding of the problem, an equivalent circuit analysis has been applied to the composite load of crucible and metal charge.

The goal of this thesis is to advance knowledge about the balance of forces acting on granular materials in the interior of the blast furnace and on the walls. Using the principles of fluid and granular flows, a mathematical model is developed and used to generate new knowledge about the influence of process parameters, under control of the blast furnace operator, on the granular stress at the level of the gas inlet and the walls. The mathematical model developed is validated under ambient conditions by comparing predictions with experimental data obtained from physical scale models of the blast furnace. Comparison of the wall gas pressure profile from a commercial blast furnace with results from the mathematical model developed, indicate that gas temperature is an important factor in estimating the magnitude of the external force exerted by gas flow on granular materials. Results also show that the vertical stress acting on the upper boundary of the coke bed in the hearth can be altered by changing variables which are under the operator’s control. These variables include the gas properties (mass flow rate and pressure) and the properties of the granular column (bulk density of granular materials and cohesive zone location). Information generated in this thesis can be used by blast furnace operators for guidance in controlling the vertical stress at the upper boundary of the coke bed in the hearth and for defining the force at this boundary for subsequent studies of hearth region. / Thesis / Doctor of Philosophy (PhD)

In this master thesis an implementation of an Organic Rankine Cycle (ORC) on a stepping furnace in a steel mill is modeled and proposed. The study is a case study at the company Štore&STEEL d.o.o. with intentions of realization. In a steel mill a stepping furnace is used to preheat the steel billets for later forging. The stepping furnace is gas fired and already has recuperation of the inlet air implemented. Still there is high temperature of the stack after recuperation, which makes application of an ORC worth of researching and modeling.First the flue gas over one year of furnace operation is analyzed in terms of temperature and volumetric flow. Mass flow and heat capacity are calculated. A layout of an ORC is proposed and modeled in IPSEpro for different temperatures of the flue gas resulting in different output powers and efficiencies. For each temperature an economic viability calculation with the method of reference cost of electric energy is done.The results are presented and the best design and conditions are proposed. The results of the thesis proved that further detailed measurements and calculation are worthwhile , as the flue gas from the stepping furnace has satisfactory conditions to make an application of an Organic Rankine cycle viable. Also the least ammount of state support to fulfill the companies conditions on return of investment is calculated and presented. Finally there are additional measurements and calculations suggested.

In the present era, with the prevailing competition, the cost of production plays a vital role. As the price of petroleum oils, especially diesel and furnace oil are growing at a steeper rate than solid fuel price, finding a substitute for furnace oil is one of the alternative available. Furnace oil used in boilers can be totally substitute by biomass with an equivalent ratio of 3.5:1 kg/liter on the basis of calorific value. This may results in saving of more than 60% of operating cost and would have attractive payback period of 6-8 months. Sri Lanka has large agriculture base and very common of having Gliricidia as an under-grow. The other biomass fuels such as paddy husk, saw dust, firewood are also available in large quantities around the country. Objective of this article is to study the conversion of presently  running furnace oil fired boiler, which is located at Ambilipitiya paper factory,Sri Lanka to biomass fired external furnace boiler namely water-wall boiler, techno economical study of the project and commissioning. Further a case study, which was done previous to this study and running successfully, is described to show the viability of the conversion using the internal furnace method. This case study was done at a Textile factory namely Brandix Finishing, Siduwa, and Sri Lanka. The results will be reducing the operating cost of the boilers and reduction of green house gas emission.  Opportunities for rural people to get extra income by farming Gliricidia, extra income from saw dust, paddy husk, and firewood are indirect benefits of the project. This report gives details of technical, environmental and commercial aspects of this unique opportunity.      Supervised by: Dr.Primal Fernando, Senior Lecturer, University of Peradeniya

Low cement castable (LCC) refractory linings, over recent years, have superseded refractory bricks in many high temperature applications. There are concerns however, pertaining to their dry-out. In particular the catastrophic destruction of LCC shapes or linings as a result of phenomenate rmede xplosives palling. This thesis describes the study of both the on-site treatments of LCCs and the physicochemical changes that occur during heating. Two types of explosive spalling event are classified,b asedo n on-siteo bservationsa ndp ost-mortems tudy. A model is presented that describes the physicochemical changes in a LCC system as it is heated from ambient to 450°C. From this model a zone of high vulnerability to explosion has been identified between 230-280°C. The dehydration of the hydrated alumina phase gibbsite (AH3), within this zone, is identified as a possible cause of explosive spalling. An investigation of polypropylene fibres, which are added to LCCs as anti-explosion additives, found that the fibres block porosity between1 60-240°CI.t is suggested that this additive system is not optimised and that polymer fibre blends may be more advantageous. The diffusion characteristics of a LCC system cured at 5 and 20°C is presented. It was found that at the lower curing temperature the diffusion rate was lower. This supports the recommendation for the use of high curing temperature to facilitate the drying of LCCs and reduce the risk of explosive spalling. A list of guidelines that could be used to establish benchmark standards for the development of best practice in industry has been compiled from the results of these studies.

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Around the world, the eutrophication of freshwater lakes and streams by the excess loading of phosphorus (P) has become one of the most important water quality issues. In Vermont, P pollution from urban and agricultural non-point sources has led to severe blooms of toxic cyanobacteria in Lake Champlain, and the degradation of the lake’s value as a drinking water source and its recreation potential. Electric arc furnace (EAF) steel slag has been identified as an effective material for use as a filter media for the removal of P from both point and non-point sources of pollution. In order to further assess the feasibility of this technology for use in Vermont, several investigations were carried out starting in the winter of 2006. Three objectives for research were identified: 1) to construct 2 EAF steel slag filters in-series at the Constructed Wetlands Research Center (CWRC) and investigate their efficiency in P, TSS and metals reduction from dairy waste water in a cold climate; 2) investigate the potential for reuse of P saturated EAF steel slag as a soil amendment and plant fertilizer by testing bioavailability of sorbed P and quantities of P released to surface runoff; 3) To elucidate the principal mechanisms responsible for the removal of P in EAF slag filters when used for the treatment of dairy effluent. The results indicated that 2 EAF steel slag filters constructed in-series are an effective method to increase the treatment efficiency and longevity of a filter system. Additionally, parameters for the concentrations of total suspended solids (TSS) and biological oxygen demand (BOD) were developed, both important factors for design of filter systems. In greenhouse trials, Medicago sativa plants achieved greater above ground biomass growth with P fertilization by triple super phosphate (TSP) than EAF steel slag at the shorter growth period (5 weeks). However, by the end of the longer growth period (10 weeks) except at the highest amendment rate, the plants treated with EAF steel slag had a higher growth rate than the TSP, suggesting that EAF steel slag is an effective slow release P source. Using a rain simulator, the amount of P lost to surface runoff from both a saturated and a semi-saturated EAF steel slag was found to be negligible, and except for total P in the saturated slag, to be below 1 mg L-1. Voltammetric analysis and geochemical modeling were used to identify possible mechanisms for the removal of P from waste effluent. The Ca mineral hydroxyapaptite and the Fe(II) mineral vivianite were both shown to be likely mechanisms given the chemical conditions in EAF steel slag filters. This research represents the first investigation of cold weather performance of EAF steel slag filters for the treatment of dairy parlor and milk house waste effluent. Additionally, it was also the first research on the bioavailability of P sorbed to EAF steel slag, and of the possibility of its reuse as a soil amendment, and of the mechanisms involved in P removal from dairy waste effluent.

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