Marcos S. P. Gomes

Numerical Modeling of an Industrial Aluminum Melting Furnace

For the present work, a numerical simulation of the 100% oxy-firing combustion process inside an industrial aluminum remelting reverb furnace is presented. Three different configurations were analyzed: (i) a staged combustion process with parallel injection jets for oxygen and natural gas, (ii) a staged combustion process with a divergent jet for the oxygen, and (iii) a non-staged combustion process, with parallel jets. In all the cases, the injections were directed towards the aluminum bath, which was maintained at constant temperature. The numerical procedure was based on the finite volume formulation. The k-e model of turbulence was selected for simulating the turbulent flow field. The combustion process was calculated based on the finite rate models of Arrhenius and Magnussen, and the Discrete Transfer Radiation model was employed for predicting the radiation heat transfer The numerical predictions allowed the determination of the flame patterns, species concentration distribution, temperature and velocity fields. This kind of analysis can be a powerful tool for evaluating design options such as the type, number and positioning of the burners. The present work illustrates a preliminary comparison of three types of burners. From the results obtained, the staged combustion process with a divergent jet presented the best configuration, since the flame length was not too long as to damage the refractory wall. Further it presented the largest region with low water vapor concentration close to the aluminum surface.

Influence of the Type of Oxidant in the Combustion of Natural Gas Inside an Aluminum Melting Furnace

The fuel used as energy source for aluminum melting is of extreme importance for a better performance of the process. However, the type of oxidant can also lead to better performance, leading to a greater preservation of the equipments. Air is more abundant and cheaper, however due to the presence of nitrogen, there is undesirable NOx formation. An alternative is to employ pure oxygen. Although it is more expensive, it can lead to a cleaner and much more efficient combustion process, by significantly altering the combustion aspects inside the furnace, such as the shape of the flame and the distribution of temperature and heat flux. In the present work, numerical simulations were carried out using the commercial package FLUENT, analyzing different cases with pure oxygen and air as the oxidant for the combustion of natural gas. The results showed the possible damages caused by the process if long or too intense and concentrated flames are present.© 2006 ASME

Performance of the Combustion Process Inside an Aluminum Melting Furnace With Natural Gas and Liquid Fuel

The choice of the type of fuel used as energy source for the aluminum melting can be of extreme importance for a better performance as well as for a greater preservation of the equipments. The option of a liquid or gaseous fuel can significantly alter the combustion aspects inside the furnace, such as the shape of the flame and the distribution of temperature and heat flux. In the present work, numerical simulations were carried out using the commercial package FLUENT, analyzing different cases with two types of fuel: a spray of liquid oil and a natural gas jet, both reacting with pure oxygen. The results showed the possible damages caused by the process if long or too intense and concentrated flames are present, increasing very much the wall temperatures and compromising the heat flux on the aluminum surface.Copyright

Combustion performance of an aluminum melting furnace operating with liquid fuel

The characteristics associated with the delivery of the fuel to be used as the energy source in any industrial combustion equipment are of extreme importance, as for example, in improving the performance of the combustion process and in the preservation of the equipment. A clean and efficient combustion may be achieved by carefully selecting the fuel and oxidant, as well as the operational conditions of the delivery system for both. In the present work, numerical simulations were carried out using the commercial code FLUENT for analyzing some of the relevant operational conditions inside an aluminum reverb furnace employing liquid fuel and air as the oxidant. Different fuel droplets sizes as well as inlet droplet stream configurations were examined. These characteristics, associated with the burner geometry and the fuel dispersion and delivery system may affect the flame shape, and consequently the temperature and the heat flux distribution within the furnace. Among the results obtained in the simulations, it was shown the possible damages to the equipment, which may occur as a result of the combustion process, if the flame is too long or too intense and concentrated.

Numerical Simulation of Natural Gas Combustion Process Using a One-Step and a Two-Step Reaction

The work evaluates the combustion of natural gas in a cylindrical furnace. The Generalized Finite Rate Reaction Model was selected for predicting the reactions. Two situations were considered. In the first case the combustion of the fuel was predicted by a single global reaction, and in the second case a two-step reaction was considered for predicting the combustion process. The conservation equations of mass, momentum, energy and chemical species were solved by the finite volume procedure, with the commercial software FLUENT. The turbulent flow was modeled by employing the two differential equation κ–e model. The solutions obtained with the two reaction models, for the temperature and species concentration fields, were compared among them and against experimental data available in the literature. It was observed that the two-step reaction model represents better the physical phenomena, showing a better agreement with the experimental data.Copyright

EXPERIMENTAL STUDIES OF THE FLOW PATTERNS IN URBAN STREET CANYONS – PART I: TALL BUILDINGS

The aim of this work was to understand the effect of tall buildings on vortices system in an urban region. Wind tunnel experiments with flow visualization and injection smoke techniques were carried out to analyze the flow pattern in an idealized urban region formed with six rectangular prismatic buildings. These scale model buildings (1/100) were arranged in a symmetric configuration with different aspect ratio H / W .

VISUALIZATION STUDIES OF THE VORTEX SYSTEM AROUND 3-D RECTANGULAR BUILDINGS

In this work, the vortex system around an isolated prismatic rectangular building was studied using smoke injection technique. This vortex system can be one of the causes of air quality problems, such as dangerous contaminants released in the near wake of the building in chemical-plants. Two models scale building with different aspect ratios were used in an atmospheric boundary wind tunnel. The qualitative analyses of video recorded images of smoke flow and laser light illumination provided a good view of the complex wind flow around an isolated building.

ESTUDO EXPERIMENTAL DO ESCOAMENTO ATMOSFÉRICO AO REDOR DE UM OBSTÁCULO ISOLADO NA CAMADA LIMITE ATMOSFÉRICA

2. Materiais e métodos Foi utilizado um túnel de vento de retorno aberto, seção de teste com (2,0X0,5X0,5)m do Ifes para os experimentos. Para a visualização do escoamento utilizou-se a técnica de injeção de fumaça e um modelo de obstáculo com dimensões de (0,15X0,12X0,12)m. Medições da velocidade foram obtidas com tubo de Pitot e um micromanômetro digital (TSI, modelo EBT720). O número de Reynolds (Re) do escoamento foi baseado na velocidade da corrente livre (U ∞ ) e dimensões características do obstáculo.