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Pyrolysis is a promising technology for renewable energy generation since it can generate products (charcoal, bio-oil and gas) with high calorific value from agro-industry wastes, such as macadamia nuts shell. Although there are some plants operating on an industrial scale, the biomass pyrolysis process is relatively recent, with several weaknesses that need to be overcome. The understanding of the pyrolysis process involves the study of biomass degradation kinetics as well as the type, configuration, and operation conditions of reactor. Thus, the main objective of this work was to contribute to some key aspects of pyrolysis of macadamia shell in conical spouted bed, that are very important for the process optimization. The pyrolysis kinetics of macadamia shell was investigated from experimental thermogravimetric data. The parameters of two of the main kinetic models available in the literature were estimated. The simulated results show that the model of Independent Parallel Reactions is what best represents the mass loss of biomass during pyrolysis. The activation energy values estimated for each component were: extractives (193-202 kJ/mol), hemicellulose (125-140 kJ/mol), cellulose (226-262 kJ/mol) and lignin (62-77 kJ/mol). With respect to the reactor, the conical spouted bed, fluid dynamic analysis of the behavior of mixture of macadamia shell and sand was performed, evaluating how static bed height (0.06, 0.08 and 0.10m) and mass fraction of biomass (25, 50 and 75%) influence on minimum spouting condition and particle segregation. It was found that the beds with largest heights are heavier, resulting in higher pressure drop and air velocity to keep the regime spouted. Furthermore, higher biomass mass fractions give higher porosity to the bed in the annular region, which reduces the flow resistance of the fluid, decreasing the air velocity and pressure drop in the minimum spouting condition. The segregation of the mixture was higher in the base of the bed, with predominance of sand in this region. By having smaller density and diameter, macadamia shell is more easily entrained into the top of the bed. In other regions, for all conditions studied, it was found acceptable levels of segregation for a biomass pyrolysis process. Finally, the identification of components of vapors generated during the fast pyrolysis (analytical micro-pyrolysis) allowed characterizing bio-oil generated at temperatures of 450, 550 and 650°C. It identified the presence of highly non-polar and intermediate polarity molecules, such as aliphatic hydrocarbons, normal and branched chain (paraffins), alicyclic hydrocarbons (cycloparaffins), olefins (normal, branched and cyclic) and aromatic (simple, polycyclic and substituted), and other chemical compounds of industrial interest.

Thickeners are equipments that uses the gravitational force as separating agent of suspended solid particle in liquid chains of industrial processes. The frequent use of the settlers in chemical industries is the reason of the interest on the development of studies on the subject. The batch sedimentation is the starting point for the project of continuous industrial units. The operation that consists on the separation of a solid-liquid suspension may have its phenomelogical representation through the introduction of the Mixtures Theory of Continuum Mechanics with the application of the continuity and movement equations for both the solid and liquid constituent and for the knowledge of constitutive equations to each system in particular. The knowledge of the particle concentration is of extreme importance for the description of the phenomenon. For diluted suspensions the solid concentration can be measured by sampling techniques, but the extension of such technique for more concentrated suspensions does not lead to the good results. In this work the batch sedimentation phenomena was studied in aqueous suspensions of different solid materials, using one not destructive technique based on the measure of gamma rays attenuation. Once the radiation beam crosses the environment as function of the local concentration for several vertical positions of the container, indirect measurements of the local concentration were done without the use of sampling for aliquot of the suspension. The batch sedimentation process presents as particular characteristic the formation of distinct regions, as the clean liquid, the free settling and the compacting region, each one separated for mobile borders that vary with the time and that increase the degree of complexity of the modelling of the phenomenon. For the description of the phenomenon it is necessary to determine the constituent equations for the pressure in solids and the permeability of the porous media, both as a function of the local solid concentration. So, a mathematical model for the unidimensional sedimentation was improved by the introduction of physical concepts of the model by d Ávila (1978) in the mathematical techniques introducted by Burger e Concha (1998). The differential-algebraic equations system was solved using the available computational package DASSL in the Scilab R , using the method of Finite Differences connected to the second order method MUSCL and the method of the lines (MOL). The Moving Mesh equations had been connected to the original system in order to increase the resolution of the problem for the estimate of the derivates of the function on each step of integration. It became possible the adaptative mesh at the regions next to the discontinuities of the phenomenon, characterizing the hy brid problem for fixed and adaptative meshes. Finally, experimental results of volumetric solid concentration as function of the position and the time of separation had been used for the validation of the model. The results of the numerical simulations had shown that the presented hyperbolic-parabolic mixed model adequately describes the physical phenomenon in all its domain without the necessity of the use of jump conditions on the mobile borders. Moreover, it was observed that quality of the solution is better for systems with low permeabilities and the quality of the simulations was restricted to the quality of the constituent equations for the solid material. Several results in static and dynamic analyses of the behavior of solid-liquids systems had become possible the physical description of the batch sedimentation based on the specific properties of the solid materials. A rigorous evaluation of the constituent equations pointed that the model of Tiller e Leu (1980) depends on the initial estimative of the adjusted parameters of the equation. According to analysis of the results it was possible to present a biparametric power model for the tension in solids. The use of good constitutive equations is the point of fundamental importance for the phenomenologial description of the batch sedimentation.

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In the present work, it was studied the ascension motion of light spheres and bubbles experimentally in Newtonian and non-Newtonian stagnated incompressible liquids in infinite field. The movement of ascension of the spheres and bubbles were monitored by a digital photographic camera (model Sony CyberShot P32). By using of a digital strobe it was possible to observe the trajectories of the spheres and bubbles. The images from th camera were processed in the Global Lab Image 2 software. The experimental runs took place in an acrylic tank which was designed to assure the absence of wall effects. In the first stage it was studied the movement of light spheres and bubbles of nitrogen in water and glycerin which are Newtonian fluids. The drag coefficient was obtained by using experimental data of velocity. Three different curves were obtained when we worked with bubbles. The first one was obtained when the characteristic dimension was the equivalent volumetric diameter. The second one was obtained by using the diameter projected on the horizontal plan for the calculation of the number of Reynolds and aspect ratio (de/dh) for the calculation of the drag coefficient. The third one was obtained by using the aspect ratio for the calculation of both, number of Reynolds and drag coefficient. KARAMANEV et al. (2005) have mentioned that a universal curve is obtained when diameter projected on the horizontal plan is used to describe the drag coefficient. In the second stage, the same procedure was used but now we worked with non- Newtonian fluids. The third stage consists of the use of a software package (FLUENT 6.3.16) to simulate the data obtained experimentally.

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

In this work was studied the simultaneous influence of sodium alginate, gelatin and glutaraldehyde concentrations in the immobilization process of Beta-galactosidase from Aspergillus oryzae and the kinetic of lactose hydrolysis by the enzyme in the soluble and immobilized forms. The free enzyme was studied at 35°C and in a pH of 4.5, showing that for substrate concentrations up to 90g/L, the Michaelis-Menten model fitted the experimental data, with a Km and Vm value of 17.83 g/L (52.13 mM) and 1032.07 gglicose/L.min.mg proteína respectively. Galactose acted as a competitive inhibitor on the free enzyme kinetic, presenting kinect constants Ki and Km values of a 1.015 and e 17.61 g/L respectively. The enzyme was stable at pH values ranging from 4.5 to 7.0 and a maximum temperature activity of 55°C, with an activation energy of 6.9 kcal/mol. The thermal stability of the enzyme was studied from 53 to 65°C, presenting a half-life of 7.7 hours at 53°C. The activation energy for the thermal deactivation process was 88.14 kcal/mol. Through a central composite design, the sodium alginate, gelatin and glutaraldehyde concentrations that maximized the -galactosidase from Aspergillus oryzae activity in the inhibition process were, respectively, 6.60%(w/v), 4.05%(w/v) and 3.64%(v/v). The immobilized enzyme presented a 20% drop in activity after 25 uses. The immobilization yield found was 30%. The enzymatic activity for the immobilized form was maximum at pH of 5.0 and 60°C, determined through a central composite design. The reaction activation energy for the immobilized enzyme was 7.74 kcal/mol. The immobilized biocatalyst was stable on pH values ranging from 4.5 to 7.0. The half-life time of the immobilized enzyme was 12.8 hours at 53°C, with a activation energy for the thermal deactivation process value of 72.03 kcal/mol . The substrate concentration influence was studied from 5 to 140 g/L of lactose and the Michaelis-Menten model fitted the experimental data, with Vm and Km values of 1428.14 glactose/min.m3catalyst and 20.62 g/L (60.3 mM), respectively. It was observed a small resistance to lactose mass transfer at the biocatalyst particles, in the immobilized enzyme, due to the high effectiveness factor values. The inhibition model fitted the experimental data and the adjusted Km and Ki values were 16.7 and 9.6g/L, respectively.

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Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Conselho Nacional de Desenvolvimento Científico e Tecnológico

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Today the used tire is considered a residue with quite inadequate final disposition as in embankments. It can cause many environmental and human health problems because it can absorb gases and to burst. When it is burned into nature it forms toxicant substances as sulfur dioxide and powder material. An alternative use of the used is as energy source in industries that demand high amount of energy in your processes because its calorific value is of approximately 33 MJ/kg. This value is high when compared with the vegetable coal calorific value. In that sense, quicklime industry can take advantage of this low cost energy source and to receive this residue. The costs with fuel in this type of industry reach up to 50% of the final cost of the lime because they operate in very high temperatures. The pyrolysis of the used tires is a way to produce high calorific value fuels from used tires with no residue generation. In this way we can give a final destination to the used tires environmentally safe. The aim of this work was to design and to build an experimental unit of pyrolysis of the used tires and to investigate the possibility to use their products as industrial fuel. Besides, we intend to study the effect of the process variables such as temperature and pressure in the process yield and in the quality of the obtained products. Some analyses of the obtained products (pyrolytic coal and oil) were made in order to compare them with traditional fuels used in quicklime industries (vegetable coal and petroleum coke). The experimental results showed that when the temperature of the pyrolyser increases the percentage of pyrolytic coal decreases. These values varied from 35.18% to 41.35%. It was also observed that the yield of the pyrolytic oil is more dependent on pyrolyser temperature than the yield of the pyrolytic coal. We get a maximum yield of the pyrolytic oil of the 45.1% when the pyrolyser was operated in 500oC. In addition, it was verified that the pyrolytic oil can be used as liquid fuel due to its very high calorific value (from 40 to 42 MJ/kg), its low viscosity (from 1.6 to 3.7 cP) and its low sulfur content (from 0.97 to 1.54%).

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Universidade Federal do Triângulo Mineiro

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Conselho Nacional de Desenvolvimento Científico e Tecnológico

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior