INFLUENCE OF THE TYPE OF OXIDANT IN THE COMBUSTION OF NATURAL GAS INSIDE AN ALUMINUM MELTING FURNACE

ABSTRACT 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. Copyright © 2006 by ASME 2 INTRODUCTION There are several industrial combustion applications which may benefit from the use of oxygen-enriched air or pure oxygen as the oxidizer during the combustion process. The resulting effects are many. Oxygen enrichment increases the flame temperature, promotes oxidation, and can lead to smaller pollutant (NOx) emissions compared with hydrocarbon-air systems, due to the absence of nitrogen. The formation of nitrogen oxides (NOx) in air-feed combustion systems represents a significant source for this pollutant within the industrial sector. With the increase in the world-wide utilization of fossil fuels, the control of NOx emissions has become an issue of global concern. Additionally, with increasing oil prices, the use of lower quality fuels will worsen the problem. Advances in computational modeling tools and the increased performance of computers have made comprehensive modeling of NOx formation and destruction a valuable tool to provide insights and understanding of the NOx reaction processes in combustion systems. This technology has the potential to enhance the application of various combustion techniques used to reduce NOx emissions from practical combustion systems Numerical modeling has became an important tool in the design and optimization of industrial equipments and also in the prediction of the emission of pollutants such as CO (carbon monoxide), SOx (sulfur oxides), and NOx. Recently, several numerical studies In the work by Frassoldati et al. [2], the attention was focused on a new procedure, based on CFD, for the determination of NOx emissions from combustion processes, which allowed the use of very detailed reaction schemes. The predictions of NOx were obtained by post-processing the flow and temperature fields, as predicted by the CFD model, and lumping together computational cells similar in terms of NOx formation. The resulting macro-cells were assumed to be a network of ideal reactors, which were simulated adopting detailed kinetic mechanisms. Nieckele et al. [3] described a numerical simulation of the 100% oxy-firing combustion process inside an industrial aluminum re-melting reverb furnace. Three different configurations were analyzed including the comparison between the staged versus non-staged combustion processes. The numerical procedure was based on the finite volume formulation and the κ−ε model of turbulence. The combustion was modeled 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 for the determination of the flame patterns, species concentration distribution, temperature and velocity fields

Upregulation of Nrf2 and decreased redox signaling contribute to renoprotective effects of chemerin receptor blockade in diabetic mice

Chemerin, acting through its receptor ChemR23, is an adipokine associated with inflammatory response, glucose and lipid metabolism and vascular function. Although this adipokine has been associated with the development and progression of kidney disease, it is not clear whether the chemerin/ChemR23 system plays a role in renal function in the context of diabetes. Therefore, we sought to determine whether ChemR23 receptor blockade prevents the development and/or progression of diabetic nephropathy and questioned the role of oxidative stress and Nrf2 in this process. Renal redox state and function were assessed in non-diabetic lean db/m and diabetic obese db/db mice treated with vehicle or CCX832 (ChemR23 antagonist). Renal reactive oxygen species (ROS) production, which was increased in diabetic mice, was attenuated by CCX832. This was associated with an increase in Nox 4 expression. Augmented protein oxidation in db/db mice was not observed when mice were treated with CCX832. CCX832 also abrogated impaired Nrf2 nuclear activity and associated downregulation in antioxidants expression in kidneys from db/db mice. Our in vivo findings highlight the role of the redox signaling and Nrf2 system as renoprotective players during chemerin receptor blockade in diabetic mice. The chemerin/ChemR23 system may be an important target to limit renal dysfunction associated with obesity-related diabetes

COVERED DISTANCES OF HANDBALL PLAYERS OBTAINED BY AN AUTOMATIC TRACKING METHOD

The aim of this work is to obtain the distances covered by handball players and their velocities during a match using a new approach based on automatic tracking method described in Figueroa et. al. (2006a, 2006b) and the Adaboost detector (Okuma, 2004). A whole game of a Brazilian regional handball championship for players under age of 21 was recorded. Applying the mentioned automatic tracking, the accumulated covered distances and the velocities were calculated for all the players. The results of average covered distances (±SD) in the 1st and 2 nd halves were 2199(±230) and 2453(±214). The results of covered distances and the velocities allow individual and collective analyses of the players by the team staff. The proposed method revealed to be a powerful tool to improve physical analysis of the handball players

Simulation of aboveground biomass production under different rainfall scenarios and soil types in the Caatinga Biome, Brazil

Drought years have a negative impact on the livestock production systems of the Brazilian semiarid region because of the strong reduction of forage production on the rangelands. Although drought is recurrent in the Brazilian semiarid, up to the present moment, there are notools that could help farmers to mitigate the effects of these extreme climate conditions. In this sense, simulation of biochemical cycles using mathematical models could be a helpful tool to understand these processes. The Century model has been largely used to estimate the impact of different environmental variables, management practices, and climate scenarios in the vegetation. The study aims to evaluate the Century model to simulate the dynamics of aboveground biomass production and soil carbon in the Caatinga ecosystem under three different rainfall scenarios: 1) Precipitation 50% below the long-term average; 2) Long-term average rainfall; 3) 50% above the long-term average rainfall. Moreover, two types of soil (sandy and clay) were evaluated in the simulations. Dry years led to 42 and 20% reductions in aboveground biomass production in the shrubby and herbaceous layers, respectively, but there were no significant differences between soil types. Further adjustments in the model are required to simulate herbaceous biomass in the Caatinga ecosystem. At the end of the adaptation phase, we expect that the Century model will generate useful information to fill the lack of knowledge about variability of forage production in the Caatinga, helping in the adaptation to possible climate changes

The Brazilian Developments on the Regional Atmospheric Modeling System (BRAMS 5.2): An Integrated Environmental Model Tuned for Tropical Areas

We present a new version of the Brazilian developments on the Regional Atmospheric Modeling System where different previous versions for weather, chemistry and carbon cycle were unified in a single integrated software system. The new version also has a new set of state-of-the-art physical parameterizations and greater computational parallel and memory usage efficiency. Together with the description of the main features are examples of the quality of the transport scheme for scalars, radiative fluxes on surface and model simulation of rainfall systems over South America in different spatial resolutions using a scale-aware convective parameterization. Besides, the simulation of the diurnal cycle of the convection and carbon dioxide concentration over the Amazon Basin, as well as carbon dioxide fluxes from biogenic processes over a large portion of South America are shown. Atmospheric chemistry examples present model performance in simulating near-surface carbon monoxide and ozone in Amazon Basin and Rio de Janeiro megacity. For tracer transport and dispersion, it is demonstrated the model capabilities to simulate the volcanic ash 3-d redistribution associated with the eruption of a Chilean volcano. Then, the gain of computational efficiency is described with some details. BRAMS has been applied for research and operational forecasting mainly in South America. Model results from the operational weather forecast of BRAMS on 5 km grid spacing in the Center for Weather Forecasting and Climate Studies, INPE/Brazil, since 2013 are used to quantify the model skill of near surface variables and rainfall. The scores show the reliability of BRAMS for the tropical and subtropical areas of South America. Requirements for keeping this modeling system competitive regarding on its functionalities and skills are discussed. At last, we highlight the relevant contribution of this work on the building up of a South American community of model developers

The Brazilian developments on the Regional Atmospheric Modeling System (BRAMS 5.2): an integrated environmental model tuned for tropical areas

We present a new version of the Brazilian developments on the Regional Atmospheric Modeling System (BRAMS), in which different previous versions for weather, chemistry, and carbon cycle were unified in a single integrated modeling system software. This new version also has a new set of state-of-the-art physical parameterizations and greater computational parallel and memory usage efficiency. The description of the main model features includes several examples illustrating the quality of the transport scheme for scalars, radiative fluxes on surface, and model simulation of rainfall systems over South America at different spatial resolutions using a scale aware convective parameterization. Additionally, the simulation of the diurnal cycle of the convection and carbon dioxide concentration over the Amazon Basin, as well as carbon dioxide fluxes from biogenic processes over a large portion of South America, are shown. Atmospheric chemistry examples show the model performance in simulating near-surface carbon monoxide and ozone in the Amazon Basin and the megacity of Rio de Janeiro. For tracer transport and dispersion, the model capabilities to simulate the volcanic ash 3-D redistribution associated with the eruption of a Chilean volcano are demonstrated. The gain of computational efficiency is described in some detail. BRAMS has been applied for research and operational forecasting mainly in South America. Model results from the operational weather forecast of BRAMS on 5 km grid spacing in the Center for Weather Forecasting and Climate Studies, INPE/Brazil, since 2013 are used to quantify the model skill of near-surface variables and rainfall. The scores show the reliability of BRAMS for the tropical and subtropical areas of South America. Requirements for keeping this modeling system competitive regarding both its functionalities and skills are discussed. Finally, we highlight the relevant contribution of this work to building a South American community of model developers.CNPqFAPESPEarth System Research Laboratory at the National Oceanic and Atmospheric Administration (ESRL/NOAA), Boulder, USAInst Nacl Pesquisas Espaciais, Ctr Previsao Tempo & Estudos Climat, Cachoeira Paulista, SP, BrazilDiv Ciência da Computação, Instituto Tecnológico de Aeronáutica, São José dos Campos, SP, BrazilUniv Estadual Paulista Unesp, Fac Ciencias, Bauru, SP, BrazilCtr Meteorol Bauru IPMet, Bauru, SP, BrazilUniv Fed Sao Paulo, Dept Ciencias Ambientais, Diadema, SP, BrazilUniv Sao Paulo, Inst Astron Geofis & Ciencias Atmosfer, Sao Paulo, SP, BrazilUniv Fed Campina Grande, Dept Ciencias Atmosfer, Campina Grande, PB, BrazilEmbrapa Informat Agr, Campinas, SP, BrazilUniv Fed Sao Paulo, Inst Ciencia & Tecnol, Sao Jose Dos Campos, SP, BrazilUniv Fed Rio Grande do Norte, Dept Ciencias Atmosfer & Climat, Programa Pos Grad Ciencias Climat, Natal, RN, BrazilInst Nacl Pesquisas Espaciais, Ctr Ciencias Sistema, Sao Jose Dos Campos, SP, BrazilUniv Fed Sao Joao Del Rei, Dept Geociencias, Sao Joao Del Rei, MG, BrazilInst Nacl Pesquisas Espaciais, Lab Associado Computacao & Matemat Aplica, Sao Jose Dos Campos, BrazilUniv Evora, Inst Ciencias Agr & Ambientais Mediterr, Evora, PortugalUniv Lusofona Humanidades & Tecnol, Ctr Interdisciplinar Desenvolvimento Ambient Gest, Lisbon, PortugalUniv Fed Pelotas, Fac Meteorol, Pelotas, RS, BrazilUnive Tecnol Fed Parana, Londrina, PR, BrazilNASA, Goddard Space Flight Ctr, Univ Space Res Assoc, Goddard Earth Sci Technol & Res Global Modeling &, Greenbelt, MD USAUniv Fed Sao Paulo, Inst Ciencia & Tecnol, Sao Jose Dos Campos, SP, BrazilUniv Fed Sao Paulo, Inst Ciencia & Tecnol, Sao Jose Dos Campos, SP, BrazilCNPq: 306340/2011-9FAPESP: 2014/01563-1FAPESP: 2015/10206-0FAPESP: 2014/01564-8Web of Scienc