No description available.

No description available.

One or the characteristics of all anthracite coal, with its low volatile content, is its ability to burn completely in a small volume. Another characteristic and disadvantage of local, semi-anthracite coal is its high ash content. It is the authors' belief that local, semi-anthracite coal can be burned most effectively for domestic heating if the furnace design allows for these characteristics. With these facts in mind, it was decided that the Anthratube had excellent possibilities as a domestic unit for burning local coal. The Anthratube, by its compactness, takes full advantage of the first characteristic; with its ash-removing grate, it overcomes to a great extent the disadvantage of the second characteristic. The purpose of this thesis was, then, to determine whether or not various sizes of local, semi-anthracite coal from the Merrimac seam could be successfully burned in the Anthratube. The coal used for this investigation was obtained from the Great Valley Anthracite Corporation located at McCoy, Virginia. 1. Pea size, local coal can be burned very successfully in the Anthratube. Overall boiler efficiencies of the unit with this size coal are high over a wide range of loads. Of the sizes of coal burned, pea size is most suitable for the Anthratube. 2. Buckwheat size, local coal canoe burned in the Anthratube with good results. The overall boiler efficiencies obtained with this size of coal are good, although not as high as those obtained with the pea coal. 3. The performance of the Anthratube with rice size, local coal is inferior to that achieved with pea and buckwheat sizes. The output of the unit is seriously limited when using this size. 4. Culm size, local coal cannot be burned in the Anthratube. / M.S.

Orientador: Jose Alexandre Matelli / Banca: Celso Eduardo Tuna / Banca: Edson Bazzo / Resumo: As usinas siderúrgicas caracterizam-se, sob o ponto de vista energético, pela grande intensidade de energia empregada em processos de redução do minério de ferro, fusão das matérias-primas e refino do aço líquido obtido. Quanto aos processos utilizados para a produção de aço, destacam-se o emprego de duas rotas tecnológicas: usinas integradas e semi-integradas (mini-mills). As usinas integradas possibilitam a redução do minério de ferro até ferro-gusa e, a partir deste, a obtenção do aço. As mini-mills caracterizam-se pelo emprego de sucatas metálicas, ferro-gusa ou ferro esponja como matérias-primas e pela obtenção, como produtos, de diferentes tipos de aço. Na operação de refino do aço líquido produzido comumente é necessário o emprego de desgaseificadores a vácuo para remoção de contaminantes e, consequentemente, atendimento às especificações do produto acabado. Com isso, as mini-mills demandam potência elétrica para os processos de fusão do aço e vapor superaquecido para obtenção de vácuo nos ejetores do processo de desgaseificação. Para atendimento a legislações ambientais, sistemas de despoeiramento devem ser aplicados às aciarias, disponibilizando grandes vazões de gases quentes provenientes do forno elétrico. A operação do sistema de despoeiramento indica expressivo potencial para recuperação de calor em processos siderúrgicos. Na presente dissertação propõe-se a coleta e análise de dados de operação do sistema de despoeiramento de um forno elétrico a arco de uma mini... (Resumo completo, clicar acesso eletrônico abaixo) / Abstract: The steel industry can be characterized by its high demand of energy in the process of reduction and production of pig iron and steel. For the production of steel the following routes can be highlighted: integrated plants and mini-mills. Integrated plants are used for production steel from iron ore, allowing the reduction of iron ore until pig iron, and pig iron to steel. Mini-mills are used for production of steel through metallic scraps and pig iron. In a mini-mill, the transformation of metallic scraps and pig iron to steel is reached in melting shop areas. The melting shop areas adopt vacuum degassers as a commonly equipment to remove contaminants of liquid steel and consequently reach requirements of finished products. As a consequence, in a melting shop, electricity is applied in electric arc furnaces and overheated steam is applied in vacuum degassers. According to environmental restrictions these melting shops are integrated with dust collectors. The dust collected in electric arc furnaces has great amount of energy and can express a high potential to heat recovering systems. The present dissertation has purpose in collect and analyzes data from an electric arc furnace with a dust collector in a Brazilian mini-mill for developing a thermal-economic analysis of a cogeneration plant integrated in this mini-mill / Mestre

In this research work, the performance of a C-type, 2nd harmonic power filter is optimized by the use of a thyristor switched damping resistor. In the design of conventional C-type, 2nd harmonic filters / the resistance of permanently connected damping resistor is to be optimized for minimization of voltage stresses on filter elements arising from switchings in transient state and for maximization of filtering effectiveness in the steady-state. Transformer inrush current during energization of power transformers and connection of filter bank to the supply are the major causes of voltage stresses arising on filter elements in transient state. These can be minimized by designing a highly damped C-type filter (low damping resistor) at the expense of inadequate filtering performance and high losses in the steady-state. On the other hand, higher damping resistance (high quality factor) is to be chosen in the design of C-type filter for satisfactory filtering of 2nd harmonic current component at the expense of higher voltage rating for capacitor bank and hence a more costly filter bank design. This drawback of conventional C-type 2nd harmonic filter circuit can be eliminated by subdividing damping resistor into two parallel parts / one is permanently connected while the other is connected to and disconnected from the circuit by back-to-back connected thyristor assemblies. The use of light triggered thyristors provides isolation between power stage and control circuit, and hence allows outdoor installation.

M. Tech. Mechanical Engineering. / Discusses the economiser design to absorb as much heat as possible within the flue gases. Fly ash particles, a product of combustion, entrained in the flue gas of the furnace part of the boiler in coal fired boilers, affect economiser thermal performance by causing erosive wear and scale on the outer surface of the economiser tubes along the flow path, which in turn increases the thermal resistance characterisation of coals in relation to combustion behaviour traditionally relies on staged quenching of the reaction and subsequent gravimetric analysis of the remaining sample. Three typical steam-raising coals are compared with regard to reactivity and broadly examined relative to their petro-graphic constituents and other standard laboratory tested samples. A significant correlation was found between the ignition temperature and the hydrogen or carbon ratio determined by the ultimate analysis, inter alia, the erosion rate and the heat transfer rate.

A mathematical model of a steam-methane reformer (SMR) was developed for use in process performance simulations and on-line monitoring of tube-wall temperatures. The model calculates temperature profiles for the outer-tube wall, inner-tube wall, furnace gas and process gas. Reformer performance ratios and composition profiles are also computed. The model inputs are the reformer inlet-stream conditions, the geometry and material properties of the furnace and catalyst-bed. The model divides the furnace and process sides of the reformer into zones of uniform temperature and composition. Radiative-heat transfer on the furnace side is modeled using the Hottel Zone method. Energy and material balances are performed on the zones to produce non-linear algebraic equations, which are solved using the Newton-Raphson method with a numerical Jacobian. Model parameters were ranked from most-estimable to least estimable using a sensitivity-based estimability analysis tool, and model outputs were fitted to limited data from an industrial SMR. The process-gas outlet temperatures were matched within 4 ºC, the upper and lower peep-hole temperatures within 12 ºC and the furnace-gas outlet temperature within 4 ºC. The process-gas outlet pressure, composition and flow rate are also accurately matched by the model. The values of the parameter estimates are physically realistic. The model developed in this thesis has the capacity to be developed into more specialized versions. Some suggestions for more specialized models include modeling of separate classes of tubes that are in different radiative environments, and detailed modeling of burner configurations, furnace-gas flow patterns and combustion heat-release patterns. / Thesis (Master, Chemical Engineering) -- Queen's University, 2009-01-06 21:50:35.04

Mémoire (M.Eng.)-- Université du Québec à Chicoutimi, 1993. / Document électronique également accessible en format PDF. CaQCU

Mémoire (M.Eng.)--Université du Québec à Chicoutimi, 1996. / Document électronique également accessible en format PDF. CaQCU

Made available in DSpace on 2014-10-09T12:52:09Z (GMT). No. of bitstreams: 0 / Made available in DSpace on 2014-10-09T13:58:11Z (GMT). No. of bitstreams: 0 / Dissertacao (Mestrado) / IPEN/D / Instituto de Pesquisas Energeticas e Nucleares - IPEN/CNEN-SP