Abstract May of 1999, Belgium's crisis over dioxin contamination in food is set to cost the country's Treasury an estimated 35 billion Belgian francs ($898.8 million), a government source record showed. On this occasion, international or community or national representative presented a report on the contamination of animal feed with dioxins including information about the chronology of the events were taken action to Dioxin. One of the biggest threats to public health is posed by a chemical known as Dioxin. Dioxin is the most toxic chemicals known to human-beings, its potency is second only to radioactive waste. Dioxin is created as an accidental byproduct during the manufacturing, and incineration process of Chlorine based products. Once released in to the environment, its contamination becomes very wide spread. Dioxin is very long lasting, and has the ability to accumulate in living tissues. It is present in your body from the moment that you are born, to the moment you die. There is no safe level of Dioxin that a person can be exposed to, the smallest amounts have bean proven to significantly increase the chances of developing cancer, as well as various other health defects. The Environmental Protection Agency (EPA) in Taiwan has been working on publishing a study of the health problems associated with dioxin. The EPA has done reassessment to the 32 possible dioxin polluted industries in Taiwan, such as waste incineration, chemical and pesticide manufacturing. The data and report has been collected and released to a final form. The Dioxin Assessment Report is measured to be the allowed contamination polluted figures toward the manufacturing industries. Especially toward arc furnace Steel industries, the dioxin assessment shows that 80.6% of Dioxin pollution is exposed by the steel industries. By the end of year 2001, Taiwan¡¦s EPA is released a ¡§Restriction of Dioxin Expose Policies and Procedures for Arc Furnace Steel Industry¡¨. The standard intake of Dioxins for new equipped arc furnace steel business from January 1, 2002 should below 0.5 ng-TEQ/Nm3. For the existing arc furnace steel industries, the 5 ng-TEQ/Nm3 regulation will be followed as a rule by the beginning of 2004. After the year of 2007, the existing arc furnace steel industries will be strictly followed the 0.5 ng-TEQ/Nm3 Dioxin Exposed Regulation. By comparison to other steel business in Japan, China, Russia and The United States, the Dioxin Exposed Regulation is harsher in Taiwan other than those countries. The purpose of this thesis is based upon the arc furnace steel manufacturing business in Taiwan. With the forbid Dioxin Exposed Regulation ruled by EPA in Taiwan, how to rebuild and sustain the arc furnace steel business in the competitive strategies while regulation and environmental challenges.

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.

No description available.

No description available.

Rapporten behandlar Kandidatarbete i maskinteknik som utfördes mot Outokumpu Stainless AB, Avesta. Syftet med arbetet var att optimera placeringen för kalkinjektionen som inte sitter optimalt placerat ur ett processoptimeringsperspektiv. Målet var att utveckla placeringen och nyttjandet av kalktillsatsen i ungen, det genom att ändra designen av valvstrukturen och kylpanelen där injektionen satt ursprungligen. Positionen för kalkinjektionen i ljusbågsugnar är normalt sett placerad i hotspotten, området i ugnen där elektronerna är närmst väggen och ger mest slitage på tegelinfodringen. För att hitta en mer optimal placering och lösning studerades befintliga placeringar hos Best in Practice, Tornios och Calverts designs anläggningar, men även ett flertal besök på Outokumpu genomfördes för att skapa en tydligare bild av processen och valvkonstruktionen. En viktig del för den här typen av projekt är konstruera lösningar och att applicera dessa på valvet med hjälp av simuleringar och 3D-modeller. På det sättet går det snabbt att testa lösningar och ge en indikation om det är något som är genomförbart eller inte. Lösningar som togs fram presenterades för Outokumpu som tog beslut om att beställa de nya kylpanelerna med den utformningen som togs fram under projektet. / This report will process a master’s thesis in mechanical engineering in cooperation with Outokumpu Stainless AB, Avesta. The purpose with this work was to optimize the position for the chalk injection which, today, is not optimized from a process position view.  The goal was to develop a position and utilize the chalk supplies and this by changing the design in the vault structure and the cooling panel where the injection originally was placed.  The position of the chalk injection in the arc furnace is normally placed in the hotspots, this is the area in the furnace where the electrodes is closest to the wall and affects the most in terms of wear of the brick lining. To be able to find a more optimal position other chalk injection designs were studied that is already in use, for example in Best in Practice, Tornios and Calverts. There were also visits at Outokumpu in Avesta to create a clearer picture of the process and the vault construction.  One important part for this project was to construct a solution and then apply this on the vault with help from a simulation and 3D-models. To be able to do this Inventor was used, the same program that Outokumpu uses. By using Inventor you can easily try out different solutions and it will give an indication if it is possible to move on with this idea or not. The solutions that were established were presented to Outokumpu who then took the decision to move on with the idea and order the new cooling panel in the design that was created throughout the project.

The reaction between carbon and iron oxide-containing slag is crucial to efficient electric arc furnace steelmaking. The reaction occurs via gaseous intermediates, and the rate of gas generation by carbon gasification is limited by the chemical reactions at the slag-gas and carbon-gas interfaces. The aim of the present study was to obtain an understanding of the gasification rate limiting factors and slag foaming behaviour that could be readily applied to industrial electric arc furnace situations. The rate of carbon gasification was measured in experimental simulations of an electric arc furnace heat with slags containing between 21.6 and 48.2 wt% 'FeO'. It was found that rate control was dominated by the carbon-gas chemical reaction. A model was developed which describes the carbon gasification rate, amount of residual carbon in the slag, gas composition, slag-gas interfacial area and bubble diameter during carbon injection into slag. The model predicts rate control by the carbon-gas chemical reaction, in agreement with experimental observations. The slag foaming behaviour was investigated, and it was found that the foaming index is a useful parameter in quantifying foam height only if void fraction is constant with respect to gas flow rate. The average bubble size was observed to be an important factor in determining foam stability, with smaller bubble size resulting in greater foam height. / Thesis / Master of Applied Science (MASc)

The objective of this study was to utilize an electric arc furnace ¡]EAF¡^in a steel mill to melt municipal incinerator fly ash ¡]MIFA¡^of different sources ¡]Plants K1 and K2¡^ and evaluate its effectiveness in aspects of environment and economy. The results of full-scale tests have shown that slag thus generated by the EAF was found to be non-hazardous based on the TCLP result and also met the standard of CNS 14602. However, EAF dust thus obtained remained hazardous as it was originally a listed waste by Taiwan EPA. Test results have indicated that this novel treatment technology would not deteriorate the quality of steel billets and bars produced. Moreover, when melting MIFAs from Plant K1¡]with 2.00 wt¢H of MIFA¡^ and Plant K2 ¡]with 3.28 wt¢H of MIFA¡^, the air quality in the steel mill surroundings and off-gas from the stack were all below the regulatory limits. Thus, it would not cause additional pollution problems from this practice. Based on the total capacity of EAFs in Taiwan, it was estimated that these EAFs would be capable of melting fly ash generated by municipal incinerators in Taiwan. From the economic perspective, this melting practice would not lower the production rate of EAF steel-making and increase the tap-to-tap cycle time, consumption of electrical energy, consumption of oxygen, and consumption of graphite electrodes. Furthermore, through this novel practice, the contents of MIFA have turned out to be able to replace some portions of quick-lime and coke powder required for steel-making. Test results have also shown that 1 wt¢H of MIFA injection would generate additional 8.93 kg of slag and 2.76 kg of EAF dust. It was found that an additional cost of NT¢C318 per ton of MIFA treated would be resulted through this practice. This treatment cost is very low as compared with NT¢C8,000 per ton of waste treated by solidification and followed by landfilling. Assuming a melting cost of NT¢C5,000 per ton of MIFA is charged by EAFs, it would save more than ten million NT¢C per year for a municipal incinerator with an annual generation of 5,840 tons of MIFA. On the other hand, for a mini-mill with an annual capacity of 264,000 tons of billets, it would have an additional income of 37 million NT¢C if 3 wt¢H of MIFA is melted while making steel.

This investigates the voltage flicker problem of a large steel plant and presents the mitigation strategy by applying the static var compensator (SVC) and cogenerator. The fluctuation of real power and reactive power consumption by an arc furnace has been measured and recorded during the steel production process. The dynamic load model of the A/C arc furnace is derived based on the actual field data and has been included in the computer simulation by the CYME software package for load flow analysis. The block diagrams of SVC controller and the excitation system of cogenerators are considered to solve the response of reactive power compensation according to the voltage fluctuation of the control bus. To maintain the electric service reliability of arc furnace when an external utility fault occurs, the tie line tripping and load shedding is implemented to prevent the tripping of cogenerator after system disturbance. It is found that the dynamic load behavior of arc furnace in the isolated industrial power system can be well compensated by the cogenerator with adaptive control of exciter and governor to generate proper reactive power and real power according to the fluctuation of bus voltage and system frequency respectively.

Voltage flicker limitation of electric utilities has been discussed in the past three decades. Arc furnace is one of the most disturbing loads that cause flicker problems in the power network. If displeasing flicker levels are predictable, then corrective solution such as static var compensation or furnace controls could be developed in cooperation between the utility and the customer. In the past, the electric fluctuations in the arc furnace voltage have been proven to be chaotic in nature. This thesis proposes a phase space approach based on nonlinearity chaotic techniques to analyze and predict voltage flicker. The determination of the phase space dimension and the application of Lyapunov exponent for flicker prediction are described. Test results have shown that accurate prediction results are obtainable for short term flicker prediction based on chaos theory.

The dissertation forms part of an ongoing project for the modelling and eventual control of an electric arc furnace (EAF) process. The main motivation behind such a project is the potential benefits that can result from automation of a process that has largely been operator controlled, often with results that leave sufficient room for improvement. Previous work in the project has resulted in the development of a generic model of the process. A later study concentrated on the control of the EAF where economic factors were taken into account. Simulation results from both studies clearly demonstrate the benefits that can accrue from successful implementation of process control. A major drawback to the practical implementation of the results is the lack of a model that is proven to be an accurate depiction of the specific plant where control is to be applied. Furthermore, the accuracy of any process model can only be verified against actual process data. There lies the raison d'etre for this dissertation: to take the existing model from the simulation environment to the real process. The main objective is to obtain a model that is able to mimic a selected set of process outputs. This is commonly a problem of system identification (SID): to select an appropriate model then fit the model to plant input/output data until the model response is similar to the plant under the same inputs (and initial conditions). The model fitting is carried out on an existing EAF model primarily by estimation of the model parameters for the EAF refining stage. Therefore the contribution of this dissertation is a model that is able to depict the EAF refining stage with reasonable accuracy. An important aspect of model fitting is experiment design. This deals with the selection of inputs and outputs that must be measured in order to estimate the desired parameters. This constitutes the problem of identifiability: what possibilities exist for estimating parameters using available I/O data or, what additional data is necessary to estimate desired parameters. In the dissertation an analysis is carried out to determine which parameters are estimable from available data. For parameters that are not estimable recommendations are made about additional measurements required to remedy the situation. Additional modelling is carried out to adapt the model to the particular process. This includes modelling to incorporate the oxyfuel subsystem, the bath oxygen content, water cooling and the effect of foaming on the arc efficiency. / Dissertation (MEng (Electronic Engineering))--University of Pretoria, 2006. / Electrical, Electronic and Computer Engineering / unrestricted