Evaluation of coffee drying costs: pre-drying on concrete terrace and complementary drying in co-current and counter-current flow dryer

The study of drying costs is an important tool to be considered when deciding on an adequate drying system. One needs to consider the energy needed for air heating, electrical energy needed to run the fans, energy to transport the product, labor costs, maintenance costs, depreciation, interest rates and breakdown costs. The objective of this study was to determine the total drying cost per bag of dry coffee beans (Coffea arabica L.), by drying processed coffee in the form of pulped cherries, with pre-drying on a concrete yard followed by complementary drying in a developed prototype dryer with concurrent and countercurrent flows. The dryer was constructed of a metallic frame and plates, with a static capacity of 1.55 m3. An initial concurrent drying stage was separated from a second counter-current flow drying stage by a repose chamber. Two treatments were applied: a) Treatment 01: 12 hours of intermittent drying with intermittent rotation and 12 hours of rest, with air temperature of 45 °C and rotation of the beans every 90 minutes for drying (for a period of 10 minutes each); b) Treatment 2: 12 hours of intermittent drying with continuous rotation and 12 hours of rest, with air temperature of 70 °C. Coffee quality was determined via a sensorial analysis (cup-test). It was concluded that: The fixed cost of the multiple flow dryer was the principal component in the total cost of drying, principally since it was treated as a prototype; Increase in the drying capacity of the system with application of treatment 02 (with continuous rotation), in relation to treatment 01 (with intermittent rotation), drastically reduced total drying costs; The results obtained from treatment 01 demonstrate its economic infeasibility, due to the elevated drying costs encountered for the proposed system under the conditions in which this study was performed.The study of drying costs is an important tool to be considered when deciding on an adequate drying system. One needs to consider the energy needed for air heating, electrical energy needed to run the fans, energy to transport the product, labor costs, maintenance costs, depreciation, interest rates and breakdown costs. The objective of this study was to determine the total drying cost per bag of dry coffee beans (Coffea arabica L.), by drying processed coffee in the form of pulped cherries, with pre-drying on a concrete yard followed by complementary drying in a developed prototype dryer with concurrent and countercurrent flows. The dryer was constructed of a metallic frame and plates, with a static capacity of 1.55 m3. An initial concurrent drying stage was separated from a second counter-current flow drying stage by a repose chamber. Two treatments were applied: a) Treatment 01: 12 hours of intermittent drying with intermittent rotation and 12 hours of rest, with air temperature of 45 °C and rotation of the beans every 90 minutes for drying (for a period of 10 minutes each); b) Treatment 2: 12 hours of intermittent drying with continuous rotation and 12 hours of rest, with air temperature of 70 °C. Coffee quality was determined via a sensorial analysis (cup-test). It was concluded that: The fixed cost of the multiple flow dryer was the principal component in the total cost of drying, principally since it was treated as a prototype; Increase in the drying capacity of the system with application of treatment 02 (with continuous rotation), in relation to treatment 01 (with intermittent rotation), drastically reduced total drying costs; The results obtained from treatment 01 demonstrate its economic infeasibility, due to the elevated drying costs encountered for the proposed system under the conditions in which this study was performed

Effects of harvesting conditions, pre-processing and storage on the quality of popcorn

Com o objetivo de identificar parâmetros de decréscimos de qualidade de milho-pipoca, foram avaliados os efeitos dos métodos de colheita e debulha de grãos, dos teores de umidade inicial, da temperatura do ar de secagem e do tempo de armazenamento sobre a capacidade de expansão das cultivares Zélia e CMS 43. A colheita foi realizada quando ambas as cultivares de milho-pipoca atingiram o teor de umidade de 19% b.u. e, posteriormente, 15% b.u. Foram utilizadas a colheita e debulha manuais e a colheita mecânica com diferentes velocidades do cilindro debulhador. O produto foi submetido à secagem artificial em camada fina. Periodicamente, realizou-se o teste-padrão de qualidade relativo à capacidade de expansão do milho-pipoca. A qualidade do grão foi afetada significativamente pela colheita mecânica e pelo aumento da temperatura do ar de secagem mas não foi reduzida durante o armazenamento. Os melhores valores de capacidade de expansão, com relação à maioria dos tratamentos, foram obtidos depois de 270 dias de armazenamento. O milho-pipoca da cultivar Zélia apresentou-se com qualidade comercial superior à da cultivar CMS 43, porém é necessário salientar que esta última encontra-se ainda em fase de desenvolvimento e melhoramento genético.Aiming to identify parameters of popcorn quality decreases, the effects of harvest and shelling methods, initial moisture contents, drying air temperature and storage time on the expansion capacity of the Zélia and CMS 43 cultivars were evaluated. The harvest was performed when both popcorn varieties reached moisture contents of 19% w.b. and, further, 15% w.b. Manual harvest and shelling and mechanic harvest with different speeds of the shelling cylinder were used. The product was submitted to artificial drying process in thin layers and also to natural drying. Periodically a quality pattern-test related to the popcorn expansion capacity was performed. The grain quality was significantly affected by mechanical harvest and by increase in the drying air temperature; there was no decrease on the physiological quality of the popcorn during the storage; the best values of expansion capacity, for most of the treatments, were obtained after 270 days of storage. The popcorn of Zélia variety showed superior commercial quality compared to the variety CMS 43. However, it is necessary to stress the fact that the latter is still in stage of development and genetic breeding

Production and nutrient accumulation in a eucalyptus plantation as a consequence of thinning intensities and fertilization

O objetivo deste trabalho foi estimar a produção de madeira e biomassa, bem como a quantidade de nutrientes acumulada, em povoamento de eucalipto submetido a intensidades de desbaste e à fertilização pós‑desbaste. O experimento foi realizado em blocos ao acaso, em parcelas subdividas, com duas repetições dos tratamentos dentro de cada bloco. Nas parcelas, foram avaliadas quatro intensidades de desbaste (0, 20, 35 e 50%) e, nas subparcelas, as condições com e sem fertilização pós‑desbaste. O desbaste foi realizado aos 89 meses e a aplicação da fertilização aos 99 meses. Os dados foram coletados aos 125 meses. O desbaste influenciou o crescimento em diâmetro, área basal, volume de madeira e biomassa. A fertilização pós‑desbaste não afetou o acúmulo de nutrientes pelo povoamento nem sua produção. O acúmulo de nutrientes na parte aérea e no tronco foi inversamente proporcional à intensidade dos desbastes. O conteúdo de Ca na serapilheira variou de acordo com os desbastes, e o de K, Ca, Mg e S de acordo com a fertilização. O desbaste tem maior influência do que a fertilização na produção florestal pós‑desbaste.The objective of this work was to estimate the production of wood and biomass, as well as nutrient accumulation, in a eucalyptus plantation subjected to thinning intensities and post‑thinning fertilization. The experiment was carried out in randomized blocks, in a split‑plot arrangement, with two replicates of treatments within each block. Thinning intensities (0, 20, 35, and 50%) were evaluated in the plots, and the fertilized and non‑fertilized conditions in the split plots. Thinning was done at 89 months, and the fertilizer application at 99 months. Data were collected at 125 months. Thinning affected the diameter growth, basal area, wood volume, and biomass. Post‑thinning fertilization did not affect nutrient accumulation by the forest, neither its production. Nutrient accumulation above ground and in the trunks was inversely proportional to thinning intensity. Calcium content in the litter varied with thinning, and the ones of K, Ca, Mg, and S, with fertilization. Thinning has a higher influence on forest post‑thinning production than fertilization

TAR FORMATION IN CORNCOB GASIFICATION

Gasification of corncobs was studied to determine the amounts of tar and condensates produced. Variables studied included corncob particle size, moisture content, airflow rate, and reactor\u27s operational mode (updraft and downdraft). The effect of temperature was also studied by running first with the unit noninsulated, and second adding insulation in the regions where pyrolysis, oxidation and gasification occurs. Results indicate that, over the range studied, tar and condensate yield increases with increasing fuel moisture, and that it does vary with air flow rate through the reactor. Updraft gasification of corncobs was found to produce about 3 to 4 times more tar than the downdraft gasification. Insulation of the reactor\u27s pyrolysis, oxidation and reduction zones increased their operating temperature and significantly reduced the yield of tar and condensate in the gas stream. Production of tar and condensate were also found to fall off with respect to time. Ultimate analysis of the corncobs, corncob charcoal, condensate and tar was performed and constituent formulas were developed. Gas from the producer was also studied and its composition, heating value, molecular weight, density and specific heat were found. Reactor\u27s mass and energy balance were also performed and gasifier efficiency was found to average 64 percent. Addition of Oxygen in the reduction zone of the gasifier was found to have potential in reducing tar yield in the gas stream. Further studies however, are needed and should be done before this result can be considered final

PROJETO, CONSTRUÇÃO E TESTE DE UMA FORNALHA A CARVÃO VEGETAL PARA SECAGEM DE CAFÉ DESPOLPADO/DESCASCADO

RESUMO Fatores como pré-processamento e secagem, influem diretamente na qualidade final do café. Sabe-se que os grãos de café despolpado/descascado geralmente originam um produto final de bebida suave, que alcança preços elevados no mercado porém, durante o processo de secagem, esses grãos são mais susceptíveis aos danos causados pelos fatores temperatura, tempo de exposição e qualidade do ar de secagem. Este trabalho foi desenvolvido na Universidade Federal de Viçosa, Departamento de Engenharia Agrícola, Viçosa, MG. Realizaram-se três testes com três repetições, nos quais foram utilizadas aberturas diferentes do topo da fornalha e o combustível usado foi carvão vegetal, proveniente de madeira de eucalipto. O ar de secagem foi mantido a temperatura de 51ºC; foram determinadas a temperatura do ar ambiente, a temperatura e a pressão do ar de secagem e o consumo de combustível, em intervalos regulares, para cada teste. A eficiência energética foi determinada pela razão entre a energia recebida pelo ar de secagem e a energia liberada pelo combustível. Com base nos resultados obtidos, verificou-se que a maior média de eficiência energética sucedeu com a maior média da vazão de secagem e com a menor média de consumo de carvão vegetal. Após se projetar, construir e testar o sistema, foi possível seu redimensionamento, por meio da determinação de parâmetros, como taxa de liberação de energia (K) e taxa de combustão (NC) mais adequados para o dimensionamento de fornalhas a carvão vegetal. Verificou-se, portanto, a viabilidade da utilização deste sistema para secagem de grãos e café despolpado ou descascado, em particular devido ao fato de gerar energia limpa com significativa eficiência

Prospects and risks of the use of castor oil as a fuel

Castor oil is more than just a raw material in great demand by the pharmaceutical and chemical industries. In several southern countries its use as a fuel is also being discussed in connection with social and ecological aspects. A few properties, in particular the extremely high viscosity and high water content, complicate the use of straight castor oil as a fuel for internal combustion engines. A better perspective may be possible by transesterification and the addition of this biodiesel to fossil diesel fuel. This, however, calls for considerably lower castor oil prices than are at present being paid on the world market