RCAAP Repository

Conselho Nacional de Desenvolvimento Científico e Tecnológico

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

The School of Chemical Engineering, Federal University of Uberlândia has been conducting studies of expression in the drying of coffee fruits using vibrated tray dryer with recycle. Among the work carried it is emphasized of Sfredo (2006), who did the study of dispersion in the coffee fruit dryer described initially. Data from the drying of coffee fruits obtained by this author, who conducted a detailed description of their experimental designs were used as the basis for application of mathematical models that can properly simulate the drying of coffee fruits in vibrated tray dryer with recycle. The use of mathematical models for drying of coffee fruits provide the simulation of the drying process considering the influence of relevant variables in the process. For modeling and simulation of mathematical models was made a literature review of thermo-physical properties of coffee fruits, which are required for accurate representation of the drying kinetics, and important in the simulation and design of dryers. A study of dimensional analysis was elaborated in which they were identified in the relevant dimensionless numbers used in drying and process simulation. There was selected three mathematical models (Arrieche, 2007, Hussain and Dincer, 2003; Chemkhi et al. 2005) in order to compare the results of simulations among themselves and with those obtained by Sfredo (2006). The models evaluated are able to calculate humidity and temperature of several internal coordinates to the fruits of coffee. In these simulations were changes of variables and applying the method of orthogonal collocation for the solution of partial differential equations used in the models. The results show that the three models adequately represented the drying of coffee fruits in trays vibrated.

The continuous decreasing of fuel fossil sources has been accelerating the seek for alternative energetic sources. The difficulty in consuming all glycerol produced, which is three times bigger than the demand, is the main concern around the biofuels process production. Given that this glycerol has different characteristics from the well consumed glycerol in the pharm business, such as color and impurities. Besides, there is a lack of defined standards in Brazil in the sense of how to dispose such product. However, alternative uses for glycerol (by-product from the biofuels production) will confirm the feasibility of the biodiesel process, particularly if we take into account its decentralized production. The glycerol steam reforming can yield up to 4 moles of H2 and 3 moles of CO per consumed mole of glycerol. In this work, the catalytic tests were performed with monometallic and bimetallic ruthenium and platinum catalyst in a tubular reactor with 30% wt of glycerol in the feed, using 6 and 20 pressures conditions. It was also carried out tests with 100 hours of reaction in order to verify its activity and stability. Along with the catalyst studies, the effects of temperature, feed flow and ruthenium particle size under monometallic and bimetallic catalyst were analyzed. Besides, it was also evaluated the reaction thermodynamics of glycerol steam reforming due to temperature, pressure and mass composition of glycerol over the production profiles of the most valuable products in the chemical equilibrium. Therefore, the objective of this work is to present the study of glycerol steam reforming employing different catalysts and under different operational conditions and evaluating its performances in the production of chemical products with high commercial value.

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Modern civilization is characterized by a large and disorganized energy consumption. As the sun is a renewable energy source, clean and inexhaustible, the operation of its light and heat becomes one of the most promising energy alternatives. Recent studies have encouraged the domestic use of solar energy replacing the use of conventional energy. The industry of solar collectors has been improved, in order to get a lower heat loss and thus a better utilization of solar energy. The use of alternative materials for the construction of collecting plates has been widely researched. This study aims to evaluate and compare the performance of two Low Cost Solar Heaters (LCSH) using PVC and polypropylene as raw material of the collector plate. Assays were performed passive (natural circulation) and active (forced circulation by peristaltic pumps) and with some setup changes in the experimental unit. These tests were performed in the main period of sunshine of the day, with the temperature values obtained by a monitoring system and data acquisition in real time. The information obtained, together with the knowledge of the values of solar radiation provided by a meteorological research center, the National Institute of Meteorology (INMET Instituto Nacional de Meteorologia), allowed the calculation of the efficiency of the collectors, the latter being defined by the ratio of heat absorbed by the plates and radiation total incident on them. Analysis of maximum temperatures attained by the systems \'boiler+plate\', the temperature gradients achieved in each setting, as well as knowledge of time and temperature obtained in the simulation of baths that use water from the reservoir of each backup catcher, lead to conclusion that the use of collector PP, together with the simplest configuration studied (thermosyphon without protection cover), provides water at a temperature for domestic use. This configuration for the LCSH has the advantages, in addition to the affordability of the population that does not yet have this technology, ease of handling and a positive contribution to eco-efficiency and environmental conservation.

Conselho Nacional de Desenvolvimento Científico e Tecnológico

The feasibility of using hydrogen as energy vector has been intensified since the combustion of H2 produces only water and energy. One possible route for obtaining H2 is from the Thermochemical water splitting cycles using two or more steps. Thus, the aim of this work was to study the production of hydrogen from thermochemical decomposition of water in two stages, using perovskite oxides LaxSr(1-x)FeO3 and LayCe(1-y)FeO3. The catalysts were prepared by sol-gel method and characterized using the following techniques: BET surface area, X-ray Diffraction (XRD), X-ray Fluorescence (XRF), Temperature Programmed Reduction (TPR) and Raman spectroscopy. The oxidation state of iron was determined by titration technique. The performance of perovskites in thermochemical water splitting was evaluated using reduction and oxidation cycles with water. In the characterization, BET analysis showed that partial substitution of La by a second metal, such as Ce or Sr, did not cause significant changes in surface area. XRF data showed that the measured composition is very close to the theoretical content calculated for the formation of the perovskites. The results of XRD and Raman spectroscopy showed that the synthesized materials have a well defined crystalline structure characteristic of perovskites. TPR analyses showed that only a small part of the material was reduced and the structure of the perovskite phase remained as predominant. The tests with oxidation and reduction cycles showed that all samples had higher H2 production in the second cycle, and the catalyst La0,95Ce0,05FeO3 obtained the best result, probably because of the good redox properties of Ce. XRD analysis of the perovskite LaFeO3 performed after two redox cycles, showed that the structure of the material did not changed significantly. This indicates that LaFeO3 perovskite-type catalysts are materials with good potential to perform the reactions of decomposition of water using oxidation and reduction cycles in order to produce hydrogen.

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

The standardization of operational procedures in chemical plants through the use of automation have became a mandatory practice for the current companies that tries or have tried a place in the commodities competitive stock. Real gains in productivity and recovery are closely related to controller s performance used in chemical process of this companies. There are a several controllers strategies in which the predictive control is a powerful tool that shows attractive results. The use of predictive control is achieved by the implementation of the control strategy in a pilot plant of a MIMO (Multiple-Input Multiple-Output) non-linear process. The nonlinear process is a experimental system of a neutralization reactor with three input flows and one output flow, and the manipulated variable are the level of reactor and the pH of mixture. The input flows are one of acid, one of base and one of buffer solution and this are the controlled variables. The information used to controller project was obtained in a open loop procedure. In this procedure, it was made disturbances in input variable and watched the output variable behavior. The MPC ( Model Predictive Control) performance was tested in a simulation and after in the pilot plant. The results achieved in simulation and practice implementation shows the excellent performance of controller to the process.

Conselho Nacional de Desenvolvimento Científico e Tecnológico

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Conselho Nacional de Desenvolvimento Científico e Tecnológico

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior

Environmental problems generated due the widespread use of fossil fuels has led the search for new energy alternatives. In this context, the biodiesel emerged as a product of great interest. However, the increase in the biofuel production leads to the production of large amounts of glycerol, which emerges as a cheap raw material with high functionality to produce different products such acrolein (currently it is obtained by selective propylene oxidation), 1,2-propanediol and others. In this study, previously, was performed a theorical and thermodynamic study of acrolein production from glycerol and others products. Catalytic tests from glycerol under different acid solid catalysts, such as materials based on alumina, niobium and zeolite, temperatures between 275 and 350°C and atmospheric pressure were performed. The catalysts were characterized by nitrogen physisorption, X-ray diffraction (XRD), temperature programmed desorption (TPD) and temperature programmed oxidation (TPO). The aim of this study is to evaluate the performance of catalysts and reaction temperature influence, in the formation of products as acrolein and acetol, main products of the reaction of dehydration of glycerol.

Phosphorus (P) is an essential macro element for maintenance of life of animals and plants. It is found in nature in the form of numerous minerals, such as apatite. The mining industry performs the extraction and processing of phosphate reserves. In the industrial process of this element considerable losses occur through industrial waste or through leaching by rain. The phosphorus dragged by rain can cause the reduction of oxigen of water bodies (eutrophication), necessary for maintaining life. Another industrial aspect concerns the production of fertilizers which traditionally utilize strong inorganic acids (sulfuric acid) for the obtaining of more soluble forms of phosphate, generating impactful byproducts to the environment. Within this context, this work proposed a possible alternative for the treatment of waste and for the traditional chemical processing, sulfuric route, by the use of Aspergillus niger, which excretes organic acid (less impactful) that by chelation mechanisms and ion exchange reactions, markedly increase the concentration of phosphorus in solution. Initially the fungus A. niger was found from soybean seeds removed from the field. 12 isolated fungi were obtained and designated numerically from 1 to 12 respectively, which were submitted to quantitative classification. In this step the two isolated fungi with the highest power of solubilization in a liquid form were selected, which are Isolated 7 (440 mg/L) and Isolated 9 (460mg/L), using the statistical methods Anova, Tukey and Scott-Knott in the quantitative classification. These solubilizattion values corresponded to ± 12% of P2O5 solubilization of phosphate rock. The next step was the experimental planning, more specifically, a Central Compound Rotational Delineation (CCRD). The relevant variables evaluated were the temperature in °C, substrate (glucose) in g/L and phosphate rock in g/L. As results were obtained for the two isolated fungi selected, the equations of the static models and graphics which represent the response surfaces between the variables. The Isolated 7 showed welldefined optimal points that were confirmed in the validation of the model, namely, 37°C for temperature, 41 g/L for the substrate and 36 g/L for the phosphate rock. The Isolated 9 didn´t show optimal points, but it showed an optimal region,namely, and 25 to 31 ° C for temperature, 28 to 37 g/L for the substrate and indifferent to phosphate rock, since this last is not shown to be significant in the experimental range. Even at this stage, it was verified the percentage of solubilization, ranging from 8 to 62% of P2O5 of the rock. After the planning it was measured the variation in the initial concentration of spores in the trials at concentrations of 105, 106, 107 and 108 spores per mL, and there was no statistical significance in the results at the end of the experiment for both fungi. It was also performed kinetic solubilization of the phosphorus, namely, to Isolated 7, the settling time has occurred within ± 36 days (5 weeks) after the start of the tests, reaching the value of 632 mg/L of P in solution. The solubilization rate was increased in the first 11 days. The settling time for the Isolated 9 occurred in ± 45 days (6 weeks), attaining the value of P in solution of 436 mg/L. The solubilization rate was increasing in the first 7 days. Finally, it was proposed a 6 L discontinuous bioreactor with aeration and recycle, which operated within optimum conditions defined above. It was obtained at the final test the value of 123 mg/L of soluble Phosphorus.

Fundação de Amparo a Pesquisa do Estado de Minas Gerais

Conselho Nacional de Desenvolvimento Científico e Tecnológico

Coordenação de Aperfeiçoamento de Pessoal de Nível Superior