Waldir Antonio Bizzo

Heat recovery from hot solid particles in a shallow fluidized bed

Abstract A heat exchanger with a shallow gas–solid fluidized bed was experimentally studied in order to analyze energy recovery from solid particles leaving a combustion process. The experiments were carried out with and without vertical baffles in a fluidized bed with immersed horizontal tubes filled with water, in a counter flow arrangement. Two particle diameters (254 and 385 μm), two solid flow rates (50 and 80 kg/h) and two gas flow rates (46 and 50 kg/h) were tested. The bed temperature along the equipment length, the mass flow rate and the inlet and outlet temperatures of solid particles, air and water were measured in order to obtain the bed-tube heat transfer coefficient and the heat exchanger effectiveness. An increment of about 55% in the heat transfer coefficient and higher values of the heat exchanger effectiveness, in experiments with the presence of baffles, was verified. The experimental results also showed that the suspension-wall heat transfer coefficient increased considerably with the solid flow rate and also when the particle diameter decreased.

Characterization of Printed Circuit Boards for Metal and Energy Recovery after Milling and Mechanical Separation

The proper disposal of electrical and electronic waste is currently a concern of researchers and environmental managers not only because of the large volume of such waste generated, but also because of the heavy metals and toxic substances it contains. This study analyzed printed circuit boards (PCBs) from discarded computers to determine their metal content and characterized them as solid waste and fuel. The analysis showed that PCBs consist of approximately 26% metal, made up mainly of copper, lead, aluminum, iron and tin, as well as other heavy metals such as cadmium and nickel. Comparison with the results of other studies indicated that the concentration of precious metals (gold and silver) has declined over time. Analysis of the leachate revealed high concentrations of cadmium and lead, giving the residue the characteristics of hazardous waste. After milling the PCBs, we found that larger amounts of metal were concentrated in smaller fractions, while the lightest fraction, obtained by density separation, had a gross calorific value of approximately 11 MJ/kg, although with a high ash content. Milling followed by density separation proved potentially useful for recovery of metals and energy-rich fractions.

Safety issues for clean liquid and gaseous fuels for cooking in the scope of sustainable development

Several fuel types have been used for cooking throughout the world, ranging from solid fuels to liquid to gas. Gaseous fuels are considered cleaner because of their inherent characteristics of low pollutant formation and emissions during handling and use. Nevertheless, from the viewpoint of sustainable development, other safety properties are important, such as flammability limits, auto-ignition temperature, specific gravity, vapour pressure, toxicity and flash point. This paper discusses several aspects of cooking fuel safety, considering traditional clean fuels such as LPG, natural gas and kerosene, and non-traditional and/or renewable fuels such as DME, producer gases, biosyngas, ethanol and ethanol-gel. The main aspects are related to transport and distribution system, product poisoning, equipment and use. Gaseous fuels are the preferred solution to replace unhealthy traditional fuels. As renewable options are still under development, LPG is often considered the short-term solution to deliver modern energy on a global scale for cooking applications.

The effects of blending diesel, ethanol, and biodiesel

ABSTRACT This work investigated the feasibility of using a blend of standard Brazilian diesel (which contains 5% biodiesel) and up to 5% ethanol. The mixture was characterized as fuel and the performance of a diesel engine operating with a blend containing 3% anhydrous ethanol, the maximum percentage of ethanol that did not reduce the cetane number of the fuel below that specified in Brazilian legislation (ANP Resolution 42), was measured. The presence of anhydrous ethanol in the mixture did not cause a significant impact on engine performance as measured by brake power, brake torque, and brake specific fuel consumption tests. The thermal efficiency of the engine used in the tests was slightly higher with standard diesel than with the diesel-biodiesel-ethanol blend.

Análise comparativa das normas de gestão de responsabilidade social e sua abrangência

Resumo: Os modelos de sistemas de gestão de responsabilidade social foram desenvolvidos para atender às demandas de organizações na implantação de práticas de gestão que sejam efetivas nas melhorias das relações com as partes interessadas, na melhoria da performance organizacional na dimensão da responsabilidade social e na promoção da sustentabilidade organizacional. Neste trabalho são analisados os principais modelos de gestão de responsabilidade social, desenvolvidos na forma de normas, certificáveis ou não, que foram comparadas quanto a origens, objetivos e conteúdo, incluindo uma análise da contribuição destas na melhoria da qualidade de vida no trabalho. Palavras-chave: SA 8000; Responsabilidade social empresarial; Normas e modelos de gestão de responsabilidade social; Auditorias sociais. Abstract: Models of social responsibility management systems have been developed to meet the demands of organizations in the implementation of management practices that are effective in improving relations with stakeholders and organizational performance in the social responsibility dimension, and promoting sustainability organizational structure. This study analyzes the main models of social responsibility management developed under the form of standards, certifiable or not, which were compared in terms of their origins, objectives, and content, including an analysis of their contribution to improving quality of life at work.