In view of very high toxicity potential of some heavy metals to aquatic life, there is a need for critical evaluation of known methods and development of new methods for purifying water and waste-water containing heavy metals. In this study, batch tests were performed to evaluate the relative efficiencies of six British Columbia coals in removing heavy metals (copper, lead, mercury and zinc) from water. On the basis of batch test data obtained, the best two coals, Kaiser Coal-Stock Pile Refuse and Kaiser Coal-Special Plant Feed, were tested on a continuous flow laboratory scale. The emphasis was placed on metal concentrations of 2 mg/1 and less for copper, lead and zinc and 5 vg/1 for mercury. The effects of adsorbate concentration, flow rate through the column (contact time), and pH of the solution on the adsorptive capacity of coal were investigated. A solution containing 0.5 mg/1 of each of copper, lead and zinc was tested to investigate the ability of the coal to remove metals from a mixture of many metals. The adsorptive capacity of the best two coals was also compared with some commercially available adsorbents. On the basis of capacity and rate of adsorption, Kaiser Coal-Stock Pile Refuse was found to be the best of the six coals tested. For the specific testing conditions in this investigation, the better metal-removing efficiency of coal as compared with activated carbon and nitrohumic acid indicate that the coal may be a feasible alternate to purify effluents containing heavy metals / Applied Science, Faculty of / Civil Engineering, Department of / Graduate

No description available.

O aquecimento indutivo e uma técnica utilizada na indústria para obter resultados de fundição, brasagem, forjaria e também tratamento térmico, aplicação foco deste trabalho. O aquecimento indutivo dá-se através de campos eletromagnéticos induzidos a uma peca metálica, a qual se deseja aquecer. Isso faz com que haja um aumento de temperatura sobre a peca devido ao efeito joule, corrente de foucault e histerese, entre outros efeitos. Para gerar os efeitos acima relatados, são necessários conversores de alta potência e frequência. Tais conversores são compostos em muitos casos de: um retificador, um capacitor filtro de barramento, um inversor e um circuito ressonante. Neste trabalho e proposto a topologia de um circuito ressonante LLC sendo chaveado por um inversor ponte completa. Como todo circuito ressonante, em operação a frequências próximas da ressonância, as correntes são elevadas e consegue-se operar com chaveamento em comutação suave. Entre algumas vantagens da topologia LLC frente a topologias como a série-ressonante, por exemplo, podem-se citar: proteção contra curto-circuito e fácil casamento de impedância entre o circuito ressonante e o inversor. No entanto, conversores com retificadores comuns possuem baixo fator de potência, FP=0,5. Para resolver este problema, propõe-se a utilização de um retificador de alto fator de potência integrado ao conversor através do inversor, formando um sistema de aquecimento indutivo integrado a um retificador com alto fator de potência. Através de um dos braços de comutação do inversor, dá-se o controle do retificador e do conversor ao mesmo tempo. A técnica apresentada resulta em um projeto de custo reduzido e baixo nível de complexidade de implantação. Para controlar a potência do sistema e utilizada uma modulação PWM assimétrica com razão cíclica variável que controla os dois conversores simultaneamente. / Induction heating is a technique used in industry to get results like casting, brazing, forging and heat treatment also, application focus of this work. Induction heating occurs through electromagnetic fields induced in a metal part, which it wants to warm up. This means that there is an increase in temperature on the piece it wants to heat up due to the Joule effect, eddy current and hysteresis, among other effects. To generate the effects reported above, high power converters and frequency are required. These converters are composed in many cases by: a rectifier, filter capacitor DC Link, an inverter and a resonant circuit. This paper proposes the topology of LLC resonant circuit being switched by a full bridge inverter. Like any resonant circuit operating at near of the resonance frequencies, the currents are high and it is possible to operate with soft switching. Among some advantages of the LLC topology against other topologies such as series resonant, for example, can be mention: protection against short-circuit and easy impedance matching between the resonant circuit and the inverter. However, converters with common rectifiers have low power factor. To solve this problem, the use of a rectifier high power factor built into the converter is proposed. This rectifier is integrated into the converter through the inverter, forming a single stage high power factor induction heating system. Through an arm of the inverter is given the control of the rectifier and the converter at the same time. The technique presented results in low cost and low complexity implementation. An asymmetric PWM modulation is used with variable duty cycle to control the power system, which controls both converters at the same time.

O aquecimento indutivo e uma técnica utilizada na indústria para obter resultados de fundição, brasagem, forjaria e também tratamento térmico, aplicação foco deste trabalho. O aquecimento indutivo dá-se através de campos eletromagnéticos induzidos a uma peca metálica, a qual se deseja aquecer. Isso faz com que haja um aumento de temperatura sobre a peca devido ao efeito joule, corrente de foucault e histerese, entre outros efeitos. Para gerar os efeitos acima relatados, são necessários conversores de alta potência e frequência. Tais conversores são compostos em muitos casos de: um retificador, um capacitor filtro de barramento, um inversor e um circuito ressonante. Neste trabalho e proposto a topologia de um circuito ressonante LLC sendo chaveado por um inversor ponte completa. Como todo circuito ressonante, em operação a frequências próximas da ressonância, as correntes são elevadas e consegue-se operar com chaveamento em comutação suave. Entre algumas vantagens da topologia LLC frente a topologias como a série-ressonante, por exemplo, podem-se citar: proteção contra curto-circuito e fácil casamento de impedância entre o circuito ressonante e o inversor. No entanto, conversores com retificadores comuns possuem baixo fator de potência, FP=0,5. Para resolver este problema, propõe-se a utilização de um retificador de alto fator de potência integrado ao conversor através do inversor, formando um sistema de aquecimento indutivo integrado a um retificador com alto fator de potência. Através de um dos braços de comutação do inversor, dá-se o controle do retificador e do conversor ao mesmo tempo. A técnica apresentada resulta em um projeto de custo reduzido e baixo nível de complexidade de implantação. Para controlar a potência do sistema e utilizada uma modulação PWM assimétrica com razão cíclica variável que controla os dois conversores simultaneamente. / Induction heating is a technique used in industry to get results like casting, brazing, forging and heat treatment also, application focus of this work. Induction heating occurs through electromagnetic fields induced in a metal part, which it wants to warm up. This means that there is an increase in temperature on the piece it wants to heat up due to the Joule effect, eddy current and hysteresis, among other effects. To generate the effects reported above, high power converters and frequency are required. These converters are composed in many cases by: a rectifier, filter capacitor DC Link, an inverter and a resonant circuit. This paper proposes the topology of LLC resonant circuit being switched by a full bridge inverter. Like any resonant circuit operating at near of the resonance frequencies, the currents are high and it is possible to operate with soft switching. Among some advantages of the LLC topology against other topologies such as series resonant, for example, can be mention: protection against short-circuit and easy impedance matching between the resonant circuit and the inverter. However, converters with common rectifiers have low power factor. To solve this problem, the use of a rectifier high power factor built into the converter is proposed. This rectifier is integrated into the converter through the inverter, forming a single stage high power factor induction heating system. Through an arm of the inverter is given the control of the rectifier and the converter at the same time. The technique presented results in low cost and low complexity implementation. An asymmetric PWM modulation is used with variable duty cycle to control the power system, which controls both converters at the same time.

by Yim Fu Cheong, Terence. / Thesis (M.B.A.)--Chinese University of Hong Kong, 1994. / Includes bibliographical references (leaves 63-67). / abstract --- p.ii / TABLE OF CONTENTS --- p.iv / LIST OF EXHIBITS --- p.vi / ACKNOWLEDGEMENT --- p.vii / CHAPTER / Chapter I. --- INTRODUCTION --- p.1 / Chapter 1.1 --- Svedala Industri AB --- p.1 / Chapter 1.2 --- Svedala Products --- p.1 / Chapter 1.2.1 --- Civil Engineering Sector --- p.2 / Chapter 1.2.2 --- Mineral Processing Sector --- p.3 / Chapter 1.2.3 --- Bulk Material Handling Sector --- p.4 / Chapter 1.3 --- Svedala Customers --- p.5 / Chapter 1.4 --- Svedala's Mission in China --- p.5 / Chapter 1.5 --- Methodology --- p.7 / Chapter II. --- FUTURE DEVELOPMENT IN CHINA --- p.10 / Chapter 2.1 --- Economic Situation --- p.10 / Chapter 2.2 --- Major Technology Introducing Projects --- p.12 / Chapter 2.3 --- What are the Bottlenecks? --- p.12 / Chapter 2 .4 --- Energy Projects --- p.19 / Chapter 2.5 --- Coal Mining Projects --- p.20 / Chapter 2.6 --- Transport Projects --- p.21 / Chapter 2.7 --- Other Construction Projects of Interest to Svedala --- p.24 / Chapter III. --- OPPORTUNITIES FOR SVEDALA --- p.25 / Chapter 3.1 --- Crushing & Screening Division --- p.25 / Chapter 3.2 --- Compaction Division --- p.26 / Chapter 3.3 --- Grinding Division --- p.27 / Chapter 3.4 --- Bulk Material Handling Division --- p.28 / Chapter IV. --- SUMMARIES OF INTERVIEWS AND IMPLICATIONS --- p.31 / Chapter 4.1 --- Crushing & Screening Division --- p.31 / Chapter 4.2 --- Compaction and Bulk Material Handling Division --- p.32 / Chapter V. --- STRENGTHS AND WEAKNESSES OF SVEDALA --- p.35 / Chapter 5.1 --- Crushing & Screening Division --- p.35 / Chapter 5.2 --- Compaction Division --- p.36 / Chapter 5.3 --- Grinding Division --- p.37 / Chapter 5.4 --- Bulk Material Handling Division --- p.38 / Chapter VI. --- THREATS TO SVEDALA --- p.40 / Chapter 6.1 --- Most-Favored-Nation (MFN) Trade Status --- p.40 / Chapter 6.2 --- Drastic Policy Changes --- p.41 / Chapter 6.3 --- Land Appreciation Tax --- p.42 / Chapter 6.4 --- Skyrocketing Costs of Operations --- p.43 / Chapter 6.5 --- Upward Trend of Interest Rates --- p.44 / Chapter 6.6 --- Government Regulations --- p.45 / Chapter VII. --- RECOMMENDED STRATEGY FOR SVEDALA --- p.46 / Chapter 7.1 --- Business Strategy for China --- p.46 / Chapter 7.2 --- Product Strategy --- p.46 / Chapter 7.3 --- Pricing Strategy --- p.49 / Chapter 7.4 --- Distribution Strategy --- p.49 / Chapter 7.5 --- Promotion Strategy --- p.51 / Chapter 7.6 --- Research & Development Strategy --- p.51 / Chapter 7.7 --- Human Resources Strategy --- p.52 / Chapter 7.8 --- Finance Strategy --- p.53 / Chapter VIII. --- CONCLUSION --- p.54 / APPENDICES --- p.57 / BIBLIOGRAPHY --- p.63 / REFERENCES --- p.66